56
CB SERIES Condensing Units Installation, Operation & Maintenance FOR YOUR SAFETY Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other appliance. WARNING If the information in this manual is not followed exactly, a fire or explosion may result causing property damage, personal injury or loss of life. WARNING QUALIFIED INSTALLER Improper installation, adjustment, alteration, service or maintenance can cause property damage, personal injury or loss of life. Startup and service must be performed by a Factory Trained Service Technician. A copy of this IOM should be kept with the unit. WARNING

Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

  • Upload
    others

  • View
    1

  • Download
    0

Embed Size (px)

Citation preview

Page 1: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

CB SERIES

Condensing Units

Installation Operation

amp Maintenance

FOR YOUR SAFETY

Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other appliance

WARNING

If the information in this manual is not followed exactly a fire or explosion may result causing property damage personal injury or loss of life

WARNING

QUALIFIED INSTALLER Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician A copy of this IOM should be kept with the unit

WARNING

2

Table of Contents AAON

reg CB Series Features and Options Introduction 5

Safety 6 CB Base Model and Features Description 10 General Description 11

Codes and Ordinances 11

Receiving Unit 11 Storage 12 Direct Expansion (DX) Condensing Units 12 Wiring Diagrams 13 General Maintenance 13

Installation 14 Lifting the Unit 14

Locating Unit 14 Mounting Isolation 15

Access Panel 15 Electrical 16

Thermostat 17 Refrigerant Piping 18

General 18

Determining Refrigerant Line Size 18

Liquid Line Sizing 19

Suction Line Sizing 20

Hot Gas Bypass Line 22

Hot Gas Reheat 22

Predetermined Line Sizes 23

Startup 26

Compressors 26 Charging Refrigerant amp Adjusting Refrigerant Charge 27

Before Charging 27

Checking Liquid Sub-cooling 27

Checking Evaporator Superheat 28

Adjusting Sub-cooling and Superheat Temperatures 28

Air Flow 29 Operation 31

Thermostat Operation 31 Compressor 31 Variable Capacity Compressor Controller 31 Low Ambient Operation 34 LAC Valve 35 Condenser Flooding 36

3

Compressor Lockouts 36

Maintenance 37 Coils 37 E-Coated Coil Cleaning 37

DX Cooling 39 Condenser Fan Motor 39 Replacement Parts 39 Warranty Service and Parts Department 39

Refrigerant Piping Diagrams 40

CB Series Startup Form 52 Literature Change History 55

4

Index of Tables and Figures

Tables Table 1 - Recommended Elevation Minimums 15 Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A 25 Table 3 - Acceptable Refrigeration Circuit Values 28

Table 4 - Performance Testing Air Flow Setpoints 29 Table 5 - R-410A Refrigerant Temperature-Pressure Chart 30 Table 6 - Demand Signal vs Compressor Capacity Modulation 32 Table 7 - Thermistor Temperature vs Resistance Values 33 Table 8 - Condenser Flooding 36

Figures Figure 1 ndash Forklift Channels amp Access Panel 14 Figure 2 ndash Condensing Unit Clearances 15 Figure 3 ndash Utility Entry 16 Figure 4 ndash Heat Pump Piping Schematic of Suction Vapor Flow Down in Double Riser 21

Figure 5 ndash Heat Pump Piping Schematic of Discharge Vapor Flow Up in Double Riser 21 Figure 6 - Riser height versus total equivalent line length 25 Figure 7 - Variable Capacity Compressor Controller 32

Figure 8 - Compressor Controller Flash Code Details 33 Figure 9 - Adjustable Fan Cycling Switch 34

Figure 10 - Piping Schematic of Example System using the LAC Valve 35 Figure 11 - Adjustable compressor lockout 36 Figure 12ndash AC only piping AHU above CU 40

Figure 13 ndash AC only piping AHU below CU 41

Figure 14 ndash Modulating hot gas reheat piping AHU above CU 42 Figure 15 ndash Modulating hot gas reheat piping AHU below CU 43 Figure 16 ndash Hot gas bypass piping AHU above CU 44

Figure 17 ndash Hot gas bypass piping AHU below CU 45 Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU 46

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU 47 Figure 20 ndash Heat pump piping AHU above CU 48 Figure 21 ndash Heat pump piping AHU below CU 49 Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU 50

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU 51

R57611 Rev A 161221

(ACP J00187)

5

AAONreg CB Series Features and Options Introduction

Energy Efficiency

Two Step or Variable Capacity Scroll

Compressor

Air-Source Heat Pump

Variable Speed Condenser Fans for Head

Pressure Control

Humidity Control

Modulating Hot Gas Reheat

Safety

Suction Pressure Transducer

Heavy Duty Wire Guards or Louvered

Panels for Condenser Coils

Automatic Low Pressure and Manual

reset High Pressure Safety Cut-outs

Suction and Liquid Line Schrader Valves

Installation and Maintenance Easily Removable Panel Access to

Service Compartment

Run Test Report and Installation Manuals

Included in Controls Compartment

Color Coded Wiring and Wiring

Diagrams

24V Control Circuit Transformer Option

System Integration

Split System Matching

Modulating Head Pressure Control

Single Point Power

High Density Foam Compressor Sound

Suppression Blanket

Environmentally Friendly

R-410A Refrigerant

Extended Life

2500 Hour Salt Spray Tested Exterior

Corrosion Paint

Optional 5 Year Non-Prorated

Compressor Warranty

Polymer E-Coated Condenser Coils

6

ELECTRIC SHOCK Electric shock hazard Before servicing shut off all electrical power to the unit including remote disconnects to avoid shock hazard or injury from rotating parts Follow proper Lockout-Tagout procedures

WARNING

Safety

Attention should be paid to the following statements

NOTE - Notes are intended to clarify the unit installation operation and maintenance

CAUTION - Caution statements are given to prevent actions that may result in

equipment damage property damage or personal injury

WARNING - Warning statements are given to prevent actions that could result in

equipment damage property damage personal injury or death

DANGER - Danger statements are given to prevent actions that will result in equipment

damage property damage severe personal injury or death

ELECTRIC SHOCK FIRE OR EXPLOSION HAZARD Failure to follow safety warnings exactly could result in dangerous operation serious injury death or property damage Improper servicing could result in dangerous operation serious injury death or property damage When servicing controls label all

wires prior to disconnecting Reconnect wires correctly

Verify proper operation after servicing Secure all doors with key-lock or nut and bolt

WARNING

QUALIFIED INSTALLER Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician A copy of this IOM should be kept with the unit

WARNING

7

FIRE EXPLOSION OR CARBON MONOXIDE POISONING HAZARD Failure to replace proper controls could result in fire explosion or carbon monoxide poisoning Failure to follow safety warnings exactly could result in serious injury death or property damage Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this appliance

WARNING

LIVE ELECTRICAL During installation testing servicing and troubleshooting of the equipment it may be necessary to work with live electrical components Only a qualified licensed electrician or individual properly trained in handling live electrical components shall perform these tasks Standard NFPA-70E an OSHA regulation requiring an Arc Flash Boundary to be field established and marked for identification of where appropriate Personal Protective Equipment (PPE) be worn should be followed

WARNING

GROUNDING REQUIRED All field installed wiring must be completed by qualified personnel Field installed wiring must comply with NECCEC local and state electrical code requirements Failure to follow code requirements could result in serious injury or death Provide proper unit ground in accordance with these code requirements

WARNING

ROTATING COMPONENTS Unit contains fans with moving parts that can cause serious injury Do not remove grill containing fans until the power to the unit has been disconnected and fan has stopped rotating

WARNING

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of 3 phase units at startup by a qualified service technician Scroll compressors are directional and can be damaged if rotated in the wrong direction Compressor rotation must be checked using suction and discharge gauges Fan motor rotation should be checked for proper operation Alterations should only be made at the unit power connection

CAUTION

8

Compartments containing hazardous voltage or rotating parts are equipped with a panel requiring tooled access Always re-install screws on the panel after installation or service is completed

CAUTION

UNIT HANDLING To prevent injury or death lifting equipment capacity shall exceed unit weight by an adequate safety factor Always test-lift unit not more than 24 inches high to verify proper center of gravity lift point to avoid unit damage injury or death

WARNING

LEAK TESTING

Do not use oxygen acetylene or air in place of refrigerant and dry nitrogen for leak testing A violent explosion may result causing injury or death

WARNING

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

COIL CLEANERS

To prevent damage to the unit do not use acidic chemical coil cleaners Do not use alkaline chemical coil cleaners with a pH value greater than 85 after mixing without first using an aluminum corrosion inhibitor in the cleaning solution

CAUTION

COIL CLEANERS

Some chemical coil cleaning compounds are caustic or toxic Use these substances only in accordance with the manufacturerrsquos usage instructions Failure to follow instructions may result in equipment damage injury or death

WARNING

9

1 Startup and service must be performed

by a Factory Trained Service

Technician

2 The unit is for outdoor use only See

General Information section for more

unit information

3 Every unit has a unique equipment

nameplate with electrical operational

and unit clearance specifications

Always refer to the unit nameplate for

specific ratings unique to the model you

have purchased

4 READ THE ENTIRE INSTALLATION

OPERATION AND MAINTENANCE

MANUAL OTHER IMPORTANT

SAFETY PRECAUTIONS ARE

PROVIDED THROUGHOUT THIS

MANUAL

5 Keep this manual and all literature

safeguarded near or on the unit

COIL CLEANING

Do not clean DX refrigerant coils with hot water or steam The use of hot water or steam on refrigerant coils will cause high pressure inside the coil tubing and damage to the coil

CAUTION

ENCLOSED AREA

Do not work in an enclosed area where refrigerant or nitrogen gases may be leaking A sufficient quantity of vapors may be present and cause

injury or death

WARNING

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

CB Series Feature String Nomenclature

Model Options Unit Feature Options

GE

N

MJ

RE

V

UN

IT

SIZ

E

VL

T

CO

MP

CK

TS

1

2

3

4

5

6

7

CB - B - 060 - 3 - B - 1 B D 0 0 D A 0

10

CB Base Model and Features Description

BASE MODEL SERIES AND GENERATION

CB

REVISION

B = Design Sequence

UNIT SIZE

024 = 24 MBH - 2 Ton - Vertical Discharge

036 = 36 MBH - 3 Ton - Vertical Discharge

048 = 48 MBH - 4 Ton - Vertical Discharge

060 = 60 MBH - 5 Ton - Vertical Discharge

VOLTAGE

1 = 230V1Φ60Hz

2 = 230V3Φ60Hz

3 = 460V3Φ60Hz

4 = 575V3Φ60Hz

8 = 208V3Φ60Hz

9 = 208V1Φ60Hz

COMPRESSOR TYPE

B = R-410A Two Step Scroll Compressor

D = R-410A Variable Capacity Scroll Compressor

F = R-410A Two Step Scroll Compressor with Sound

Blanket

H = R-410A Variable Capacity Scroll Compressor

with Sound Blanket

NUMBER OF CIRCUITS

1 = One Circuit

FEATURE 1 AMBIENT CONTROL 0 = Standard (55degF Ambient)

B = Adjustable Fan Cycling (35degF Ambient)

D = Modulating Fan Pressure Control (35degF

Ambient)

F = Flooded Condenser Ambient Controls (0degF) +

Option B

G = Flooded Condenser Ambient Controls (0degF) +

Option D

FEATURE 2 REFRIGERATION

OPTIONS 0 = Standard - Split System Air Conditioner

A = External Hot Gas Bypass

B = Split System Heat Pump

D = Modulating Hot Gas Reheat

F = Options A + D

G = Options B + D

FEATURE 3 CONTROLS

0 = Standard - Terminal Block

A = Suction Pressure Transducer (F1- Wattmaster

Reheat)

H = Control Circuit Transformer

S = Suction Pressure Transducer (Not F1 -

Wattmaster Controls)

T = Control Circuit Transformer w Suction Pressure

Transducer

FEATURE 4 COIL PROTECTION

0 = Standard

A = Polymer E-Coated Coil

FEATURE 5 CABINET OPTIONS D = Standard ndash Louvered Panels + 2500 Hour Salt-

Spray Tested Exterior Paint

G = Wire Grille + 2500 Hour Salt-Spray Tested

Exterior Paint

FEATURE 6 WARRANTY 0 = Standard

A = Second to Fifth Year Extended Compressor

Warranty

FEATURE 7 TYPE 0 = Standard

X = Special Pricing Authorization

11

General Description

AAON CB Series condensing units have

been designed for outdoor installation only

Startup and service must be performed by a

Factory Trained Service Technician

Codes and Ordinances

CB Series units have been tested and

certified by ETL in accordance with UL

Safety Standard 1995CSA C222 No 236

System should be sized in accordance with

the American Society of Heating

Refrigeration and Air Conditioning

Engineers Handbook

Installation of CB Series units must conform

to the ICC standards of the International

Mechanical Code the International Building

Code and local building plumbing and

waste water codes All appliances must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Receiving Unit

When received the unit should be checked

for damage that might have occurred in

transit If damage is found it should be noted

on the carrierrsquos Freight Bill A request for

inspection by carrierrsquos agent should be made

in writing at once

Nameplate should be checked to ensure the

correct model sizes and voltages have been

received to match the job requirements

If repairs must be made to damaged goods

then the factory should be notified before

any repair action is taken in order to protect

the warranty Certain equipment alteration

repair and manipulation of equipment

without the manufacturerrsquos consent may

void the product warranty Contact AAON

Warranty Department for assistance with

handling damaged goods repairs and

freight claims (903) 236-4403

NOTE Upon receipt check shipment for

items that ship loose Consult order and

shipment documentation to identify potential

loose-shipped items Loose-shipped items

The Clean Air Act of 1990 bans the intentional venting of refrigerant as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed

CAUTION

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a Factory Trained Service Technician

WARNING

SHARP EDGES

Coils and sheet metal surfaces present sharp edges and care must be taken when working with equipment

WARNING

Failure to observe the following instructions will result in premature failure of your system and possible voiding of the warranty

WARNING

12

may have been placed inside the unit cabinet

for security Installers and owners should

secure all doors with locks or nuts and bolts

to prevent unauthorized access

The warranty card must be completed in full

and returned to AAON not more than 3

months after the unit is delivered

Storage

If installation will not occur immediately

following delivery store equipment in a dry

protected area away from construction

traffic and in the proper orientation as

marked on the packaging with all internal

packaging in place Secure all loose-shipped

items

Direct Expansion (DX) Condensing Units

CB Series condensing units are factory

assembled and wired including a full charge

of R-410A refrigerant for up to 25 feet of

line set Systems with the modulating hot

gas reheat option will require refrigerant to

be field added because of the additional

refrigerant components and piping

associated with the system

Failure to observe the following instructions

may result in premature failure of your

system and possible voiding of the

warranty

Never cut off the main power supply to the

unit except for servicing emergency or

complete shutdown of the unit When power

is cut off from the unit compressors using

crankcase heaters cannot prevent refrigerant

migration This means the compressor may

cool down and liquid refrigerant may

accumulate in the compressor Since the

compressor is designed to pump refrigerant

gas damage may occur when power is

restored

If power to the unit must be off for more

than an hour turn the thermostat system

switch to ldquoOffrdquo or turn the unit off at the

control panel and then cut off the main

power supply Leave the unit off until the

main power supply has been turned on again

for at least 24 hours This will give the

crankcase heater time to clear any liquid

accumulation out of the compressor before it

is required to run

Always control the system from the

thermostat or control panel never at the

main power supply except for servicing

emergency or complete shutdown of the

unit

The standard compressors must be on a

minimum of 5 minutes and off for a

minimum of 5 minutes The cycle rate must

be no more than 6 starts per hour

The variable capacity compressors must be

on a minimum of 3 minutes and off for a

minimum of 3 minutes The cycle rate must

be no more than 10 starts per hour

The compressor life will be seriously

shortened by reduced lubrication and the

pumping of excessive amounts of liquid oil

and liquid refrigerant

CRANKCASE HEATER OPERATION

Units are equipped with compressor crankcase heaters which should be energized at least 24 hours prior to cooling operation to clear any liquid refrigerant from the compressors

CAUTION

13

Note Low Ambient Operation

Units without a low ambient option such as

condenser fan cycling or the 0degF low

ambient option will not operate in the

cooling mode of operation properly when

the outdoor temperature is below 55degF Low

ambient andor air handling unit economizer

options are recommended if cooling

operation below 55degF is expected

Note Multiple Systems with Multiple

Thermostats

When several heating and cooling split

systems are used to condition a space all

thermostat switches must be set in either

heating mode cooling mode or off Do not

leave part of the systems switched to the

opposite mode Cooling only systems should

be switched off at the thermostat during the

heating season

Wiring Diagrams

Unit specific wiring diagram is laminated in

plastic and located inside the controls

compartment door

General Maintenance

When the initial startup is made and on a

periodic schedule during operation it is

necessary to perform routine service checks

on the performance of the condensing unit

This includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

14

Installation

AAON equipment has been designed for

quick and easy installation

Lifting the Unit

CB Series condensing units have channels

underneath the base which provide lifting

access to the underside of the equipment and

allow moving and placement without

physical damage

Figure 1 ndash Forklift Channels amp Access Panel

Dollies andor carts are recommended to lift

and place the unit to prevent damage to the

equipment and injury to the installer

Care should be taken if using spreader bars

blocking or other lifting devices to prevent

any damage to the cabinet coil or

condensing fans

Before lifting unit be sure that all shipping

material has been removed from unit

Hoist unit to a point directly above the

condenser pad and lower unit into the

proper place Unit may also be positioned

with a dolly When the unit is in place

remove the dolly or lifting device Make

sure the unit is properly seated and level

Locating Unit

CB Series condensing units are designed for

outdoor application and placement at ground

level or on a rooftop Units must be placed

on a level and solid foundation that can

support the unitrsquos weight

When rooftop mounted a steel frame must

be provided that will support the unit above

the roof itself for load distribution

When installed at ground level a one-piece

concrete slab or composite condenser pad

should be used with footings that extend

below the frost line (a substantial base that

will not settle) Slab should be surrounded

by a graveled area for proper drainage and

should not adjoin the building as sound and

vibration may be transmitted to the

structure Care must also be taken to protect

the coils and fins from damage due to

vandalism or other hazards

Airflow to and from the condensing unit

must not be restricted Coils and fans must

be free of any obstructions and debris in

order to start and operate properly with a

correct amount of airflow Obstruction to air

flow will result in decreased performance

and efficiency

The installation position must provide at

least one foot of clearance from the wall for

proper air flow to the coils When multiple

units are mounted adjacent to each other the

clearance required between them is three

feet

Service compartment must be accessible for

periodic servicing of controls safety

devices and refrigerant serviceshutoff

valves At least two feet of clearance on this

Incorrect lifting can cause damage to the unit

CAUTION

15

corner of the unit is recommended for

service

Figure 2 ndash Condensing Unit Clearances

Condensing units should not be installed in

an enclosure or pit that is deeper than the

height of the unit When recessed

installation is necessary the clearance to

maintain proper airflow is at least three feet

CB Series condensing units are single

circuited with vertical air discharge There

must be no obstruction above the equipment

Do not place the unit under an overhang

Placement relative to the building air intakes

and other structures must be carefully

selected Consider the effects of outdoor fan

noise on conditioned space and any adjacent

occupied space It is recommended that the

unit be placed so that discharge does not

blow toward windows less than 25 feet

away

Heat pumps require special location

consideration in areas where snow

accumulation can become an obstruction

and in areas with prolonged continuous

subfreezing temperatures Heat pump unit

bases are cutout under the outdoor coil to

permit drainage of frost accumulation The

unit must be situated to permit free

unobstructed drainage of the defrost water

and ice A minimum 3 inches clearance

under the outdoor coil is required in the

milder climates In more severe weather

locations it is recommended that the unit be

elevated to allow unobstructed drainage and

airflow

Table 1 - Recommended Elevation

Minimums

Design

Temperature

Suggest Minimum

Elevation

+15 F and above 3rdquo

-5 F to +17 F 8rdquo

Below -5 F 12rdquo

Mounting Isolation

For roof mounted applications or anytime

vibration transmission is a factor vibration

isolators may be used

Access Panel

Access panel is provided to electrical

compartment To remove the panel

unscrew the four screws

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

16

Electrical

Verify the unit nameplate agrees with the

power supply Connect power and control

field wiring as shown on the unit wiring

diagram provided with the unit

Route power and control wiring separately

through the utility entry right above the

service valves Do not run power and signal

wires in the same conduit

Figure 3 ndash Utility Entry

Size supply conductors based on the unit

MCA rating Supply conductors must be

rated a minimum of 75degC

Protect the branch circuit in accordance with

code requirements The unit must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Note Units are factory wired for 208V

230V 460V or 575V In some units the

208V and 230V options may also be

provided in single or three phase

configurations The transformer

configuration must be checked by a

qualified technician prior to startup

Wire power leads to the unit terminal block

All wiring beyond this point has been done

by the manufacturer and cannot be modified

without affecting the units agencysafety

certification

All units require field supplied electrical

overcurrent and short circuit protection

Device must not be sized larger than the

Maximum Overcurrent Protection (MOP)

shown on the unit nameplate

Codes may require a disconnect switch be

within sight of the unit

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Before attempting to perform any installation service or maintenance shut off all electrical power to the unit at the disconnect switches Unit may have multiple power supplies Failure to disconnect power could result in dangerous operation serious injury death or property damage

WARNING

17

It is recommended that the field installed

overcurrent protection or disconnect switch

not be installed on the unit

Supply voltage must be within the minmax

range shown on the unit nameplate

Available short circuit current should not

exceed the short circuit current rating

(SCCR) shown on the unit nameplate

Three phase voltage imbalance will cause

motor overheating and premature failure

The maximum allowable imbalance is 20

Voltage imbalance is defined as 100 times

the maximum deviation from the average

voltage divided by the average voltage

Example

(221V+230V+227V)3 = 226V then

100(226V-221V)226V = 22 which

exceeds the allowable imbalance

Check voltage imbalance at the unit

disconnect switch and at the compressor

terminal Contact your local power company

for line voltage corrections

Installing contractor must check for proper

motor rotation and check blower motor

amperage listed on the motor nameplate is

not exceeded

Wire control signals to the unitrsquos low

voltage terminal block located in the

controls compartment

If any factory installed wiring must be

replaced use a minimum 105degC type AWM

insulated conductors

Thermostat

If a thermostat is used for unit control

thermostat should be located on an inside

wall 4-5 feet above the floor where it will

not be subjected to drafts sun exposure or

heat from electrical fixtures or appliances

Follow thermostat manufacturerrsquos

instructions for general installation

procedure

Thermostat control wiring size must be large

enough to prevent excess voltage drop and

ensure proper operation

All external devices must be powered via a

separate external power supply

Units with the modulating hot gas reheat

dehumidification feature must use a

humidistat or a thermostat with a normally

closed (NC) dehumidification option The

following thermostats have been approved

for usage with the dehumidification feature

Robertshawreg 9825i2 Thermostat

Honeywell VisionPROreg IAQ Thermostat

AAON Mini Controller

Three phase voltage imbalance will cause motor overheating and premature failure

CAUTION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 2: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

2

Table of Contents AAON

reg CB Series Features and Options Introduction 5

Safety 6 CB Base Model and Features Description 10 General Description 11

Codes and Ordinances 11

Receiving Unit 11 Storage 12 Direct Expansion (DX) Condensing Units 12 Wiring Diagrams 13 General Maintenance 13

Installation 14 Lifting the Unit 14

Locating Unit 14 Mounting Isolation 15

Access Panel 15 Electrical 16

Thermostat 17 Refrigerant Piping 18

General 18

Determining Refrigerant Line Size 18

Liquid Line Sizing 19

Suction Line Sizing 20

Hot Gas Bypass Line 22

Hot Gas Reheat 22

Predetermined Line Sizes 23

Startup 26

Compressors 26 Charging Refrigerant amp Adjusting Refrigerant Charge 27

Before Charging 27

Checking Liquid Sub-cooling 27

Checking Evaporator Superheat 28

Adjusting Sub-cooling and Superheat Temperatures 28

Air Flow 29 Operation 31

Thermostat Operation 31 Compressor 31 Variable Capacity Compressor Controller 31 Low Ambient Operation 34 LAC Valve 35 Condenser Flooding 36

3

Compressor Lockouts 36

Maintenance 37 Coils 37 E-Coated Coil Cleaning 37

DX Cooling 39 Condenser Fan Motor 39 Replacement Parts 39 Warranty Service and Parts Department 39

Refrigerant Piping Diagrams 40

CB Series Startup Form 52 Literature Change History 55

4

Index of Tables and Figures

Tables Table 1 - Recommended Elevation Minimums 15 Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A 25 Table 3 - Acceptable Refrigeration Circuit Values 28

Table 4 - Performance Testing Air Flow Setpoints 29 Table 5 - R-410A Refrigerant Temperature-Pressure Chart 30 Table 6 - Demand Signal vs Compressor Capacity Modulation 32 Table 7 - Thermistor Temperature vs Resistance Values 33 Table 8 - Condenser Flooding 36

Figures Figure 1 ndash Forklift Channels amp Access Panel 14 Figure 2 ndash Condensing Unit Clearances 15 Figure 3 ndash Utility Entry 16 Figure 4 ndash Heat Pump Piping Schematic of Suction Vapor Flow Down in Double Riser 21

Figure 5 ndash Heat Pump Piping Schematic of Discharge Vapor Flow Up in Double Riser 21 Figure 6 - Riser height versus total equivalent line length 25 Figure 7 - Variable Capacity Compressor Controller 32

Figure 8 - Compressor Controller Flash Code Details 33 Figure 9 - Adjustable Fan Cycling Switch 34

Figure 10 - Piping Schematic of Example System using the LAC Valve 35 Figure 11 - Adjustable compressor lockout 36 Figure 12ndash AC only piping AHU above CU 40

Figure 13 ndash AC only piping AHU below CU 41

Figure 14 ndash Modulating hot gas reheat piping AHU above CU 42 Figure 15 ndash Modulating hot gas reheat piping AHU below CU 43 Figure 16 ndash Hot gas bypass piping AHU above CU 44

Figure 17 ndash Hot gas bypass piping AHU below CU 45 Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU 46

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU 47 Figure 20 ndash Heat pump piping AHU above CU 48 Figure 21 ndash Heat pump piping AHU below CU 49 Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU 50

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU 51

R57611 Rev A 161221

(ACP J00187)

5

AAONreg CB Series Features and Options Introduction

Energy Efficiency

Two Step or Variable Capacity Scroll

Compressor

Air-Source Heat Pump

Variable Speed Condenser Fans for Head

Pressure Control

Humidity Control

Modulating Hot Gas Reheat

Safety

Suction Pressure Transducer

Heavy Duty Wire Guards or Louvered

Panels for Condenser Coils

Automatic Low Pressure and Manual

reset High Pressure Safety Cut-outs

Suction and Liquid Line Schrader Valves

Installation and Maintenance Easily Removable Panel Access to

Service Compartment

Run Test Report and Installation Manuals

Included in Controls Compartment

Color Coded Wiring and Wiring

Diagrams

24V Control Circuit Transformer Option

System Integration

Split System Matching

Modulating Head Pressure Control

Single Point Power

High Density Foam Compressor Sound

Suppression Blanket

Environmentally Friendly

R-410A Refrigerant

Extended Life

2500 Hour Salt Spray Tested Exterior

Corrosion Paint

Optional 5 Year Non-Prorated

Compressor Warranty

Polymer E-Coated Condenser Coils

6

ELECTRIC SHOCK Electric shock hazard Before servicing shut off all electrical power to the unit including remote disconnects to avoid shock hazard or injury from rotating parts Follow proper Lockout-Tagout procedures

WARNING

Safety

Attention should be paid to the following statements

NOTE - Notes are intended to clarify the unit installation operation and maintenance

CAUTION - Caution statements are given to prevent actions that may result in

equipment damage property damage or personal injury

WARNING - Warning statements are given to prevent actions that could result in

equipment damage property damage personal injury or death

DANGER - Danger statements are given to prevent actions that will result in equipment

damage property damage severe personal injury or death

ELECTRIC SHOCK FIRE OR EXPLOSION HAZARD Failure to follow safety warnings exactly could result in dangerous operation serious injury death or property damage Improper servicing could result in dangerous operation serious injury death or property damage When servicing controls label all

wires prior to disconnecting Reconnect wires correctly

Verify proper operation after servicing Secure all doors with key-lock or nut and bolt

WARNING

QUALIFIED INSTALLER Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician A copy of this IOM should be kept with the unit

WARNING

7

FIRE EXPLOSION OR CARBON MONOXIDE POISONING HAZARD Failure to replace proper controls could result in fire explosion or carbon monoxide poisoning Failure to follow safety warnings exactly could result in serious injury death or property damage Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this appliance

WARNING

LIVE ELECTRICAL During installation testing servicing and troubleshooting of the equipment it may be necessary to work with live electrical components Only a qualified licensed electrician or individual properly trained in handling live electrical components shall perform these tasks Standard NFPA-70E an OSHA regulation requiring an Arc Flash Boundary to be field established and marked for identification of where appropriate Personal Protective Equipment (PPE) be worn should be followed

WARNING

GROUNDING REQUIRED All field installed wiring must be completed by qualified personnel Field installed wiring must comply with NECCEC local and state electrical code requirements Failure to follow code requirements could result in serious injury or death Provide proper unit ground in accordance with these code requirements

WARNING

ROTATING COMPONENTS Unit contains fans with moving parts that can cause serious injury Do not remove grill containing fans until the power to the unit has been disconnected and fan has stopped rotating

WARNING

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of 3 phase units at startup by a qualified service technician Scroll compressors are directional and can be damaged if rotated in the wrong direction Compressor rotation must be checked using suction and discharge gauges Fan motor rotation should be checked for proper operation Alterations should only be made at the unit power connection

CAUTION

8

Compartments containing hazardous voltage or rotating parts are equipped with a panel requiring tooled access Always re-install screws on the panel after installation or service is completed

CAUTION

UNIT HANDLING To prevent injury or death lifting equipment capacity shall exceed unit weight by an adequate safety factor Always test-lift unit not more than 24 inches high to verify proper center of gravity lift point to avoid unit damage injury or death

WARNING

LEAK TESTING

Do not use oxygen acetylene or air in place of refrigerant and dry nitrogen for leak testing A violent explosion may result causing injury or death

WARNING

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

COIL CLEANERS

To prevent damage to the unit do not use acidic chemical coil cleaners Do not use alkaline chemical coil cleaners with a pH value greater than 85 after mixing without first using an aluminum corrosion inhibitor in the cleaning solution

CAUTION

COIL CLEANERS

Some chemical coil cleaning compounds are caustic or toxic Use these substances only in accordance with the manufacturerrsquos usage instructions Failure to follow instructions may result in equipment damage injury or death

WARNING

9

1 Startup and service must be performed

by a Factory Trained Service

Technician

2 The unit is for outdoor use only See

General Information section for more

unit information

3 Every unit has a unique equipment

nameplate with electrical operational

and unit clearance specifications

Always refer to the unit nameplate for

specific ratings unique to the model you

have purchased

4 READ THE ENTIRE INSTALLATION

OPERATION AND MAINTENANCE

MANUAL OTHER IMPORTANT

SAFETY PRECAUTIONS ARE

PROVIDED THROUGHOUT THIS

MANUAL

5 Keep this manual and all literature

safeguarded near or on the unit

COIL CLEANING

Do not clean DX refrigerant coils with hot water or steam The use of hot water or steam on refrigerant coils will cause high pressure inside the coil tubing and damage to the coil

CAUTION

ENCLOSED AREA

Do not work in an enclosed area where refrigerant or nitrogen gases may be leaking A sufficient quantity of vapors may be present and cause

injury or death

WARNING

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

CB Series Feature String Nomenclature

Model Options Unit Feature Options

GE

N

MJ

RE

V

UN

IT

SIZ

E

VL

T

CO

MP

CK

TS

1

2

3

4

5

6

7

CB - B - 060 - 3 - B - 1 B D 0 0 D A 0

10

CB Base Model and Features Description

BASE MODEL SERIES AND GENERATION

CB

REVISION

B = Design Sequence

UNIT SIZE

024 = 24 MBH - 2 Ton - Vertical Discharge

036 = 36 MBH - 3 Ton - Vertical Discharge

048 = 48 MBH - 4 Ton - Vertical Discharge

060 = 60 MBH - 5 Ton - Vertical Discharge

VOLTAGE

1 = 230V1Φ60Hz

2 = 230V3Φ60Hz

3 = 460V3Φ60Hz

4 = 575V3Φ60Hz

8 = 208V3Φ60Hz

9 = 208V1Φ60Hz

COMPRESSOR TYPE

B = R-410A Two Step Scroll Compressor

D = R-410A Variable Capacity Scroll Compressor

F = R-410A Two Step Scroll Compressor with Sound

Blanket

H = R-410A Variable Capacity Scroll Compressor

with Sound Blanket

NUMBER OF CIRCUITS

1 = One Circuit

FEATURE 1 AMBIENT CONTROL 0 = Standard (55degF Ambient)

B = Adjustable Fan Cycling (35degF Ambient)

D = Modulating Fan Pressure Control (35degF

Ambient)

F = Flooded Condenser Ambient Controls (0degF) +

Option B

G = Flooded Condenser Ambient Controls (0degF) +

Option D

FEATURE 2 REFRIGERATION

OPTIONS 0 = Standard - Split System Air Conditioner

A = External Hot Gas Bypass

B = Split System Heat Pump

D = Modulating Hot Gas Reheat

F = Options A + D

G = Options B + D

FEATURE 3 CONTROLS

0 = Standard - Terminal Block

A = Suction Pressure Transducer (F1- Wattmaster

Reheat)

H = Control Circuit Transformer

S = Suction Pressure Transducer (Not F1 -

Wattmaster Controls)

T = Control Circuit Transformer w Suction Pressure

Transducer

FEATURE 4 COIL PROTECTION

0 = Standard

A = Polymer E-Coated Coil

FEATURE 5 CABINET OPTIONS D = Standard ndash Louvered Panels + 2500 Hour Salt-

Spray Tested Exterior Paint

G = Wire Grille + 2500 Hour Salt-Spray Tested

Exterior Paint

FEATURE 6 WARRANTY 0 = Standard

A = Second to Fifth Year Extended Compressor

Warranty

FEATURE 7 TYPE 0 = Standard

X = Special Pricing Authorization

11

General Description

AAON CB Series condensing units have

been designed for outdoor installation only

Startup and service must be performed by a

Factory Trained Service Technician

Codes and Ordinances

CB Series units have been tested and

certified by ETL in accordance with UL

Safety Standard 1995CSA C222 No 236

System should be sized in accordance with

the American Society of Heating

Refrigeration and Air Conditioning

Engineers Handbook

Installation of CB Series units must conform

to the ICC standards of the International

Mechanical Code the International Building

Code and local building plumbing and

waste water codes All appliances must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Receiving Unit

When received the unit should be checked

for damage that might have occurred in

transit If damage is found it should be noted

on the carrierrsquos Freight Bill A request for

inspection by carrierrsquos agent should be made

in writing at once

Nameplate should be checked to ensure the

correct model sizes and voltages have been

received to match the job requirements

If repairs must be made to damaged goods

then the factory should be notified before

any repair action is taken in order to protect

the warranty Certain equipment alteration

repair and manipulation of equipment

without the manufacturerrsquos consent may

void the product warranty Contact AAON

Warranty Department for assistance with

handling damaged goods repairs and

freight claims (903) 236-4403

NOTE Upon receipt check shipment for

items that ship loose Consult order and

shipment documentation to identify potential

loose-shipped items Loose-shipped items

The Clean Air Act of 1990 bans the intentional venting of refrigerant as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed

CAUTION

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a Factory Trained Service Technician

WARNING

SHARP EDGES

Coils and sheet metal surfaces present sharp edges and care must be taken when working with equipment

WARNING

Failure to observe the following instructions will result in premature failure of your system and possible voiding of the warranty

WARNING

12

may have been placed inside the unit cabinet

for security Installers and owners should

secure all doors with locks or nuts and bolts

to prevent unauthorized access

The warranty card must be completed in full

and returned to AAON not more than 3

months after the unit is delivered

Storage

If installation will not occur immediately

following delivery store equipment in a dry

protected area away from construction

traffic and in the proper orientation as

marked on the packaging with all internal

packaging in place Secure all loose-shipped

items

Direct Expansion (DX) Condensing Units

CB Series condensing units are factory

assembled and wired including a full charge

of R-410A refrigerant for up to 25 feet of

line set Systems with the modulating hot

gas reheat option will require refrigerant to

be field added because of the additional

refrigerant components and piping

associated with the system

Failure to observe the following instructions

may result in premature failure of your

system and possible voiding of the

warranty

Never cut off the main power supply to the

unit except for servicing emergency or

complete shutdown of the unit When power

is cut off from the unit compressors using

crankcase heaters cannot prevent refrigerant

migration This means the compressor may

cool down and liquid refrigerant may

accumulate in the compressor Since the

compressor is designed to pump refrigerant

gas damage may occur when power is

restored

If power to the unit must be off for more

than an hour turn the thermostat system

switch to ldquoOffrdquo or turn the unit off at the

control panel and then cut off the main

power supply Leave the unit off until the

main power supply has been turned on again

for at least 24 hours This will give the

crankcase heater time to clear any liquid

accumulation out of the compressor before it

is required to run

Always control the system from the

thermostat or control panel never at the

main power supply except for servicing

emergency or complete shutdown of the

unit

The standard compressors must be on a

minimum of 5 minutes and off for a

minimum of 5 minutes The cycle rate must

be no more than 6 starts per hour

The variable capacity compressors must be

on a minimum of 3 minutes and off for a

minimum of 3 minutes The cycle rate must

be no more than 10 starts per hour

The compressor life will be seriously

shortened by reduced lubrication and the

pumping of excessive amounts of liquid oil

and liquid refrigerant

CRANKCASE HEATER OPERATION

Units are equipped with compressor crankcase heaters which should be energized at least 24 hours prior to cooling operation to clear any liquid refrigerant from the compressors

CAUTION

13

Note Low Ambient Operation

Units without a low ambient option such as

condenser fan cycling or the 0degF low

ambient option will not operate in the

cooling mode of operation properly when

the outdoor temperature is below 55degF Low

ambient andor air handling unit economizer

options are recommended if cooling

operation below 55degF is expected

Note Multiple Systems with Multiple

Thermostats

When several heating and cooling split

systems are used to condition a space all

thermostat switches must be set in either

heating mode cooling mode or off Do not

leave part of the systems switched to the

opposite mode Cooling only systems should

be switched off at the thermostat during the

heating season

Wiring Diagrams

Unit specific wiring diagram is laminated in

plastic and located inside the controls

compartment door

General Maintenance

When the initial startup is made and on a

periodic schedule during operation it is

necessary to perform routine service checks

on the performance of the condensing unit

This includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

14

Installation

AAON equipment has been designed for

quick and easy installation

Lifting the Unit

CB Series condensing units have channels

underneath the base which provide lifting

access to the underside of the equipment and

allow moving and placement without

physical damage

Figure 1 ndash Forklift Channels amp Access Panel

Dollies andor carts are recommended to lift

and place the unit to prevent damage to the

equipment and injury to the installer

Care should be taken if using spreader bars

blocking or other lifting devices to prevent

any damage to the cabinet coil or

condensing fans

Before lifting unit be sure that all shipping

material has been removed from unit

Hoist unit to a point directly above the

condenser pad and lower unit into the

proper place Unit may also be positioned

with a dolly When the unit is in place

remove the dolly or lifting device Make

sure the unit is properly seated and level

Locating Unit

CB Series condensing units are designed for

outdoor application and placement at ground

level or on a rooftop Units must be placed

on a level and solid foundation that can

support the unitrsquos weight

When rooftop mounted a steel frame must

be provided that will support the unit above

the roof itself for load distribution

When installed at ground level a one-piece

concrete slab or composite condenser pad

should be used with footings that extend

below the frost line (a substantial base that

will not settle) Slab should be surrounded

by a graveled area for proper drainage and

should not adjoin the building as sound and

vibration may be transmitted to the

structure Care must also be taken to protect

the coils and fins from damage due to

vandalism or other hazards

Airflow to and from the condensing unit

must not be restricted Coils and fans must

be free of any obstructions and debris in

order to start and operate properly with a

correct amount of airflow Obstruction to air

flow will result in decreased performance

and efficiency

The installation position must provide at

least one foot of clearance from the wall for

proper air flow to the coils When multiple

units are mounted adjacent to each other the

clearance required between them is three

feet

Service compartment must be accessible for

periodic servicing of controls safety

devices and refrigerant serviceshutoff

valves At least two feet of clearance on this

Incorrect lifting can cause damage to the unit

CAUTION

15

corner of the unit is recommended for

service

Figure 2 ndash Condensing Unit Clearances

Condensing units should not be installed in

an enclosure or pit that is deeper than the

height of the unit When recessed

installation is necessary the clearance to

maintain proper airflow is at least three feet

CB Series condensing units are single

circuited with vertical air discharge There

must be no obstruction above the equipment

Do not place the unit under an overhang

Placement relative to the building air intakes

and other structures must be carefully

selected Consider the effects of outdoor fan

noise on conditioned space and any adjacent

occupied space It is recommended that the

unit be placed so that discharge does not

blow toward windows less than 25 feet

away

Heat pumps require special location

consideration in areas where snow

accumulation can become an obstruction

and in areas with prolonged continuous

subfreezing temperatures Heat pump unit

bases are cutout under the outdoor coil to

permit drainage of frost accumulation The

unit must be situated to permit free

unobstructed drainage of the defrost water

and ice A minimum 3 inches clearance

under the outdoor coil is required in the

milder climates In more severe weather

locations it is recommended that the unit be

elevated to allow unobstructed drainage and

airflow

Table 1 - Recommended Elevation

Minimums

Design

Temperature

Suggest Minimum

Elevation

+15 F and above 3rdquo

-5 F to +17 F 8rdquo

Below -5 F 12rdquo

Mounting Isolation

For roof mounted applications or anytime

vibration transmission is a factor vibration

isolators may be used

Access Panel

Access panel is provided to electrical

compartment To remove the panel

unscrew the four screws

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

16

Electrical

Verify the unit nameplate agrees with the

power supply Connect power and control

field wiring as shown on the unit wiring

diagram provided with the unit

Route power and control wiring separately

through the utility entry right above the

service valves Do not run power and signal

wires in the same conduit

Figure 3 ndash Utility Entry

Size supply conductors based on the unit

MCA rating Supply conductors must be

rated a minimum of 75degC

Protect the branch circuit in accordance with

code requirements The unit must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Note Units are factory wired for 208V

230V 460V or 575V In some units the

208V and 230V options may also be

provided in single or three phase

configurations The transformer

configuration must be checked by a

qualified technician prior to startup

Wire power leads to the unit terminal block

All wiring beyond this point has been done

by the manufacturer and cannot be modified

without affecting the units agencysafety

certification

All units require field supplied electrical

overcurrent and short circuit protection

Device must not be sized larger than the

Maximum Overcurrent Protection (MOP)

shown on the unit nameplate

Codes may require a disconnect switch be

within sight of the unit

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Before attempting to perform any installation service or maintenance shut off all electrical power to the unit at the disconnect switches Unit may have multiple power supplies Failure to disconnect power could result in dangerous operation serious injury death or property damage

WARNING

17

It is recommended that the field installed

overcurrent protection or disconnect switch

not be installed on the unit

Supply voltage must be within the minmax

range shown on the unit nameplate

Available short circuit current should not

exceed the short circuit current rating

(SCCR) shown on the unit nameplate

Three phase voltage imbalance will cause

motor overheating and premature failure

The maximum allowable imbalance is 20

Voltage imbalance is defined as 100 times

the maximum deviation from the average

voltage divided by the average voltage

Example

(221V+230V+227V)3 = 226V then

100(226V-221V)226V = 22 which

exceeds the allowable imbalance

Check voltage imbalance at the unit

disconnect switch and at the compressor

terminal Contact your local power company

for line voltage corrections

Installing contractor must check for proper

motor rotation and check blower motor

amperage listed on the motor nameplate is

not exceeded

Wire control signals to the unitrsquos low

voltage terminal block located in the

controls compartment

If any factory installed wiring must be

replaced use a minimum 105degC type AWM

insulated conductors

Thermostat

If a thermostat is used for unit control

thermostat should be located on an inside

wall 4-5 feet above the floor where it will

not be subjected to drafts sun exposure or

heat from electrical fixtures or appliances

Follow thermostat manufacturerrsquos

instructions for general installation

procedure

Thermostat control wiring size must be large

enough to prevent excess voltage drop and

ensure proper operation

All external devices must be powered via a

separate external power supply

Units with the modulating hot gas reheat

dehumidification feature must use a

humidistat or a thermostat with a normally

closed (NC) dehumidification option The

following thermostats have been approved

for usage with the dehumidification feature

Robertshawreg 9825i2 Thermostat

Honeywell VisionPROreg IAQ Thermostat

AAON Mini Controller

Three phase voltage imbalance will cause motor overheating and premature failure

CAUTION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 3: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

3

Compressor Lockouts 36

Maintenance 37 Coils 37 E-Coated Coil Cleaning 37

DX Cooling 39 Condenser Fan Motor 39 Replacement Parts 39 Warranty Service and Parts Department 39

Refrigerant Piping Diagrams 40

CB Series Startup Form 52 Literature Change History 55

4

Index of Tables and Figures

Tables Table 1 - Recommended Elevation Minimums 15 Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A 25 Table 3 - Acceptable Refrigeration Circuit Values 28

Table 4 - Performance Testing Air Flow Setpoints 29 Table 5 - R-410A Refrigerant Temperature-Pressure Chart 30 Table 6 - Demand Signal vs Compressor Capacity Modulation 32 Table 7 - Thermistor Temperature vs Resistance Values 33 Table 8 - Condenser Flooding 36

Figures Figure 1 ndash Forklift Channels amp Access Panel 14 Figure 2 ndash Condensing Unit Clearances 15 Figure 3 ndash Utility Entry 16 Figure 4 ndash Heat Pump Piping Schematic of Suction Vapor Flow Down in Double Riser 21

Figure 5 ndash Heat Pump Piping Schematic of Discharge Vapor Flow Up in Double Riser 21 Figure 6 - Riser height versus total equivalent line length 25 Figure 7 - Variable Capacity Compressor Controller 32

Figure 8 - Compressor Controller Flash Code Details 33 Figure 9 - Adjustable Fan Cycling Switch 34

Figure 10 - Piping Schematic of Example System using the LAC Valve 35 Figure 11 - Adjustable compressor lockout 36 Figure 12ndash AC only piping AHU above CU 40

Figure 13 ndash AC only piping AHU below CU 41

Figure 14 ndash Modulating hot gas reheat piping AHU above CU 42 Figure 15 ndash Modulating hot gas reheat piping AHU below CU 43 Figure 16 ndash Hot gas bypass piping AHU above CU 44

Figure 17 ndash Hot gas bypass piping AHU below CU 45 Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU 46

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU 47 Figure 20 ndash Heat pump piping AHU above CU 48 Figure 21 ndash Heat pump piping AHU below CU 49 Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU 50

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU 51

R57611 Rev A 161221

(ACP J00187)

5

AAONreg CB Series Features and Options Introduction

Energy Efficiency

Two Step or Variable Capacity Scroll

Compressor

Air-Source Heat Pump

Variable Speed Condenser Fans for Head

Pressure Control

Humidity Control

Modulating Hot Gas Reheat

Safety

Suction Pressure Transducer

Heavy Duty Wire Guards or Louvered

Panels for Condenser Coils

Automatic Low Pressure and Manual

reset High Pressure Safety Cut-outs

Suction and Liquid Line Schrader Valves

Installation and Maintenance Easily Removable Panel Access to

Service Compartment

Run Test Report and Installation Manuals

Included in Controls Compartment

Color Coded Wiring and Wiring

Diagrams

24V Control Circuit Transformer Option

System Integration

Split System Matching

Modulating Head Pressure Control

Single Point Power

High Density Foam Compressor Sound

Suppression Blanket

Environmentally Friendly

R-410A Refrigerant

Extended Life

2500 Hour Salt Spray Tested Exterior

Corrosion Paint

Optional 5 Year Non-Prorated

Compressor Warranty

Polymer E-Coated Condenser Coils

6

ELECTRIC SHOCK Electric shock hazard Before servicing shut off all electrical power to the unit including remote disconnects to avoid shock hazard or injury from rotating parts Follow proper Lockout-Tagout procedures

WARNING

Safety

Attention should be paid to the following statements

NOTE - Notes are intended to clarify the unit installation operation and maintenance

CAUTION - Caution statements are given to prevent actions that may result in

equipment damage property damage or personal injury

WARNING - Warning statements are given to prevent actions that could result in

equipment damage property damage personal injury or death

DANGER - Danger statements are given to prevent actions that will result in equipment

damage property damage severe personal injury or death

ELECTRIC SHOCK FIRE OR EXPLOSION HAZARD Failure to follow safety warnings exactly could result in dangerous operation serious injury death or property damage Improper servicing could result in dangerous operation serious injury death or property damage When servicing controls label all

wires prior to disconnecting Reconnect wires correctly

Verify proper operation after servicing Secure all doors with key-lock or nut and bolt

WARNING

QUALIFIED INSTALLER Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician A copy of this IOM should be kept with the unit

WARNING

7

FIRE EXPLOSION OR CARBON MONOXIDE POISONING HAZARD Failure to replace proper controls could result in fire explosion or carbon monoxide poisoning Failure to follow safety warnings exactly could result in serious injury death or property damage Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this appliance

WARNING

LIVE ELECTRICAL During installation testing servicing and troubleshooting of the equipment it may be necessary to work with live electrical components Only a qualified licensed electrician or individual properly trained in handling live electrical components shall perform these tasks Standard NFPA-70E an OSHA regulation requiring an Arc Flash Boundary to be field established and marked for identification of where appropriate Personal Protective Equipment (PPE) be worn should be followed

WARNING

GROUNDING REQUIRED All field installed wiring must be completed by qualified personnel Field installed wiring must comply with NECCEC local and state electrical code requirements Failure to follow code requirements could result in serious injury or death Provide proper unit ground in accordance with these code requirements

WARNING

ROTATING COMPONENTS Unit contains fans with moving parts that can cause serious injury Do not remove grill containing fans until the power to the unit has been disconnected and fan has stopped rotating

WARNING

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of 3 phase units at startup by a qualified service technician Scroll compressors are directional and can be damaged if rotated in the wrong direction Compressor rotation must be checked using suction and discharge gauges Fan motor rotation should be checked for proper operation Alterations should only be made at the unit power connection

CAUTION

8

Compartments containing hazardous voltage or rotating parts are equipped with a panel requiring tooled access Always re-install screws on the panel after installation or service is completed

CAUTION

UNIT HANDLING To prevent injury or death lifting equipment capacity shall exceed unit weight by an adequate safety factor Always test-lift unit not more than 24 inches high to verify proper center of gravity lift point to avoid unit damage injury or death

WARNING

LEAK TESTING

Do not use oxygen acetylene or air in place of refrigerant and dry nitrogen for leak testing A violent explosion may result causing injury or death

WARNING

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

COIL CLEANERS

To prevent damage to the unit do not use acidic chemical coil cleaners Do not use alkaline chemical coil cleaners with a pH value greater than 85 after mixing without first using an aluminum corrosion inhibitor in the cleaning solution

CAUTION

COIL CLEANERS

Some chemical coil cleaning compounds are caustic or toxic Use these substances only in accordance with the manufacturerrsquos usage instructions Failure to follow instructions may result in equipment damage injury or death

WARNING

9

1 Startup and service must be performed

by a Factory Trained Service

Technician

2 The unit is for outdoor use only See

General Information section for more

unit information

3 Every unit has a unique equipment

nameplate with electrical operational

and unit clearance specifications

Always refer to the unit nameplate for

specific ratings unique to the model you

have purchased

4 READ THE ENTIRE INSTALLATION

OPERATION AND MAINTENANCE

MANUAL OTHER IMPORTANT

SAFETY PRECAUTIONS ARE

PROVIDED THROUGHOUT THIS

MANUAL

5 Keep this manual and all literature

safeguarded near or on the unit

COIL CLEANING

Do not clean DX refrigerant coils with hot water or steam The use of hot water or steam on refrigerant coils will cause high pressure inside the coil tubing and damage to the coil

CAUTION

ENCLOSED AREA

Do not work in an enclosed area where refrigerant or nitrogen gases may be leaking A sufficient quantity of vapors may be present and cause

injury or death

WARNING

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

CB Series Feature String Nomenclature

Model Options Unit Feature Options

GE

N

MJ

RE

V

UN

IT

SIZ

E

VL

T

CO

MP

CK

TS

1

2

3

4

5

6

7

CB - B - 060 - 3 - B - 1 B D 0 0 D A 0

10

CB Base Model and Features Description

BASE MODEL SERIES AND GENERATION

CB

REVISION

B = Design Sequence

UNIT SIZE

024 = 24 MBH - 2 Ton - Vertical Discharge

036 = 36 MBH - 3 Ton - Vertical Discharge

048 = 48 MBH - 4 Ton - Vertical Discharge

060 = 60 MBH - 5 Ton - Vertical Discharge

VOLTAGE

1 = 230V1Φ60Hz

2 = 230V3Φ60Hz

3 = 460V3Φ60Hz

4 = 575V3Φ60Hz

8 = 208V3Φ60Hz

9 = 208V1Φ60Hz

COMPRESSOR TYPE

B = R-410A Two Step Scroll Compressor

D = R-410A Variable Capacity Scroll Compressor

F = R-410A Two Step Scroll Compressor with Sound

Blanket

H = R-410A Variable Capacity Scroll Compressor

with Sound Blanket

NUMBER OF CIRCUITS

1 = One Circuit

FEATURE 1 AMBIENT CONTROL 0 = Standard (55degF Ambient)

B = Adjustable Fan Cycling (35degF Ambient)

D = Modulating Fan Pressure Control (35degF

Ambient)

F = Flooded Condenser Ambient Controls (0degF) +

Option B

G = Flooded Condenser Ambient Controls (0degF) +

Option D

FEATURE 2 REFRIGERATION

OPTIONS 0 = Standard - Split System Air Conditioner

A = External Hot Gas Bypass

B = Split System Heat Pump

D = Modulating Hot Gas Reheat

F = Options A + D

G = Options B + D

FEATURE 3 CONTROLS

0 = Standard - Terminal Block

A = Suction Pressure Transducer (F1- Wattmaster

Reheat)

H = Control Circuit Transformer

S = Suction Pressure Transducer (Not F1 -

Wattmaster Controls)

T = Control Circuit Transformer w Suction Pressure

Transducer

FEATURE 4 COIL PROTECTION

0 = Standard

A = Polymer E-Coated Coil

FEATURE 5 CABINET OPTIONS D = Standard ndash Louvered Panels + 2500 Hour Salt-

Spray Tested Exterior Paint

G = Wire Grille + 2500 Hour Salt-Spray Tested

Exterior Paint

FEATURE 6 WARRANTY 0 = Standard

A = Second to Fifth Year Extended Compressor

Warranty

FEATURE 7 TYPE 0 = Standard

X = Special Pricing Authorization

11

General Description

AAON CB Series condensing units have

been designed for outdoor installation only

Startup and service must be performed by a

Factory Trained Service Technician

Codes and Ordinances

CB Series units have been tested and

certified by ETL in accordance with UL

Safety Standard 1995CSA C222 No 236

System should be sized in accordance with

the American Society of Heating

Refrigeration and Air Conditioning

Engineers Handbook

Installation of CB Series units must conform

to the ICC standards of the International

Mechanical Code the International Building

Code and local building plumbing and

waste water codes All appliances must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Receiving Unit

When received the unit should be checked

for damage that might have occurred in

transit If damage is found it should be noted

on the carrierrsquos Freight Bill A request for

inspection by carrierrsquos agent should be made

in writing at once

Nameplate should be checked to ensure the

correct model sizes and voltages have been

received to match the job requirements

If repairs must be made to damaged goods

then the factory should be notified before

any repair action is taken in order to protect

the warranty Certain equipment alteration

repair and manipulation of equipment

without the manufacturerrsquos consent may

void the product warranty Contact AAON

Warranty Department for assistance with

handling damaged goods repairs and

freight claims (903) 236-4403

NOTE Upon receipt check shipment for

items that ship loose Consult order and

shipment documentation to identify potential

loose-shipped items Loose-shipped items

The Clean Air Act of 1990 bans the intentional venting of refrigerant as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed

CAUTION

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a Factory Trained Service Technician

WARNING

SHARP EDGES

Coils and sheet metal surfaces present sharp edges and care must be taken when working with equipment

WARNING

Failure to observe the following instructions will result in premature failure of your system and possible voiding of the warranty

WARNING

12

may have been placed inside the unit cabinet

for security Installers and owners should

secure all doors with locks or nuts and bolts

to prevent unauthorized access

The warranty card must be completed in full

and returned to AAON not more than 3

months after the unit is delivered

Storage

If installation will not occur immediately

following delivery store equipment in a dry

protected area away from construction

traffic and in the proper orientation as

marked on the packaging with all internal

packaging in place Secure all loose-shipped

items

Direct Expansion (DX) Condensing Units

CB Series condensing units are factory

assembled and wired including a full charge

of R-410A refrigerant for up to 25 feet of

line set Systems with the modulating hot

gas reheat option will require refrigerant to

be field added because of the additional

refrigerant components and piping

associated with the system

Failure to observe the following instructions

may result in premature failure of your

system and possible voiding of the

warranty

Never cut off the main power supply to the

unit except for servicing emergency or

complete shutdown of the unit When power

is cut off from the unit compressors using

crankcase heaters cannot prevent refrigerant

migration This means the compressor may

cool down and liquid refrigerant may

accumulate in the compressor Since the

compressor is designed to pump refrigerant

gas damage may occur when power is

restored

If power to the unit must be off for more

than an hour turn the thermostat system

switch to ldquoOffrdquo or turn the unit off at the

control panel and then cut off the main

power supply Leave the unit off until the

main power supply has been turned on again

for at least 24 hours This will give the

crankcase heater time to clear any liquid

accumulation out of the compressor before it

is required to run

Always control the system from the

thermostat or control panel never at the

main power supply except for servicing

emergency or complete shutdown of the

unit

The standard compressors must be on a

minimum of 5 minutes and off for a

minimum of 5 minutes The cycle rate must

be no more than 6 starts per hour

The variable capacity compressors must be

on a minimum of 3 minutes and off for a

minimum of 3 minutes The cycle rate must

be no more than 10 starts per hour

The compressor life will be seriously

shortened by reduced lubrication and the

pumping of excessive amounts of liquid oil

and liquid refrigerant

CRANKCASE HEATER OPERATION

Units are equipped with compressor crankcase heaters which should be energized at least 24 hours prior to cooling operation to clear any liquid refrigerant from the compressors

CAUTION

13

Note Low Ambient Operation

Units without a low ambient option such as

condenser fan cycling or the 0degF low

ambient option will not operate in the

cooling mode of operation properly when

the outdoor temperature is below 55degF Low

ambient andor air handling unit economizer

options are recommended if cooling

operation below 55degF is expected

Note Multiple Systems with Multiple

Thermostats

When several heating and cooling split

systems are used to condition a space all

thermostat switches must be set in either

heating mode cooling mode or off Do not

leave part of the systems switched to the

opposite mode Cooling only systems should

be switched off at the thermostat during the

heating season

Wiring Diagrams

Unit specific wiring diagram is laminated in

plastic and located inside the controls

compartment door

General Maintenance

When the initial startup is made and on a

periodic schedule during operation it is

necessary to perform routine service checks

on the performance of the condensing unit

This includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

14

Installation

AAON equipment has been designed for

quick and easy installation

Lifting the Unit

CB Series condensing units have channels

underneath the base which provide lifting

access to the underside of the equipment and

allow moving and placement without

physical damage

Figure 1 ndash Forklift Channels amp Access Panel

Dollies andor carts are recommended to lift

and place the unit to prevent damage to the

equipment and injury to the installer

Care should be taken if using spreader bars

blocking or other lifting devices to prevent

any damage to the cabinet coil or

condensing fans

Before lifting unit be sure that all shipping

material has been removed from unit

Hoist unit to a point directly above the

condenser pad and lower unit into the

proper place Unit may also be positioned

with a dolly When the unit is in place

remove the dolly or lifting device Make

sure the unit is properly seated and level

Locating Unit

CB Series condensing units are designed for

outdoor application and placement at ground

level or on a rooftop Units must be placed

on a level and solid foundation that can

support the unitrsquos weight

When rooftop mounted a steel frame must

be provided that will support the unit above

the roof itself for load distribution

When installed at ground level a one-piece

concrete slab or composite condenser pad

should be used with footings that extend

below the frost line (a substantial base that

will not settle) Slab should be surrounded

by a graveled area for proper drainage and

should not adjoin the building as sound and

vibration may be transmitted to the

structure Care must also be taken to protect

the coils and fins from damage due to

vandalism or other hazards

Airflow to and from the condensing unit

must not be restricted Coils and fans must

be free of any obstructions and debris in

order to start and operate properly with a

correct amount of airflow Obstruction to air

flow will result in decreased performance

and efficiency

The installation position must provide at

least one foot of clearance from the wall for

proper air flow to the coils When multiple

units are mounted adjacent to each other the

clearance required between them is three

feet

Service compartment must be accessible for

periodic servicing of controls safety

devices and refrigerant serviceshutoff

valves At least two feet of clearance on this

Incorrect lifting can cause damage to the unit

CAUTION

15

corner of the unit is recommended for

service

Figure 2 ndash Condensing Unit Clearances

Condensing units should not be installed in

an enclosure or pit that is deeper than the

height of the unit When recessed

installation is necessary the clearance to

maintain proper airflow is at least three feet

CB Series condensing units are single

circuited with vertical air discharge There

must be no obstruction above the equipment

Do not place the unit under an overhang

Placement relative to the building air intakes

and other structures must be carefully

selected Consider the effects of outdoor fan

noise on conditioned space and any adjacent

occupied space It is recommended that the

unit be placed so that discharge does not

blow toward windows less than 25 feet

away

Heat pumps require special location

consideration in areas where snow

accumulation can become an obstruction

and in areas with prolonged continuous

subfreezing temperatures Heat pump unit

bases are cutout under the outdoor coil to

permit drainage of frost accumulation The

unit must be situated to permit free

unobstructed drainage of the defrost water

and ice A minimum 3 inches clearance

under the outdoor coil is required in the

milder climates In more severe weather

locations it is recommended that the unit be

elevated to allow unobstructed drainage and

airflow

Table 1 - Recommended Elevation

Minimums

Design

Temperature

Suggest Minimum

Elevation

+15 F and above 3rdquo

-5 F to +17 F 8rdquo

Below -5 F 12rdquo

Mounting Isolation

For roof mounted applications or anytime

vibration transmission is a factor vibration

isolators may be used

Access Panel

Access panel is provided to electrical

compartment To remove the panel

unscrew the four screws

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

16

Electrical

Verify the unit nameplate agrees with the

power supply Connect power and control

field wiring as shown on the unit wiring

diagram provided with the unit

Route power and control wiring separately

through the utility entry right above the

service valves Do not run power and signal

wires in the same conduit

Figure 3 ndash Utility Entry

Size supply conductors based on the unit

MCA rating Supply conductors must be

rated a minimum of 75degC

Protect the branch circuit in accordance with

code requirements The unit must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Note Units are factory wired for 208V

230V 460V or 575V In some units the

208V and 230V options may also be

provided in single or three phase

configurations The transformer

configuration must be checked by a

qualified technician prior to startup

Wire power leads to the unit terminal block

All wiring beyond this point has been done

by the manufacturer and cannot be modified

without affecting the units agencysafety

certification

All units require field supplied electrical

overcurrent and short circuit protection

Device must not be sized larger than the

Maximum Overcurrent Protection (MOP)

shown on the unit nameplate

Codes may require a disconnect switch be

within sight of the unit

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Before attempting to perform any installation service or maintenance shut off all electrical power to the unit at the disconnect switches Unit may have multiple power supplies Failure to disconnect power could result in dangerous operation serious injury death or property damage

WARNING

17

It is recommended that the field installed

overcurrent protection or disconnect switch

not be installed on the unit

Supply voltage must be within the minmax

range shown on the unit nameplate

Available short circuit current should not

exceed the short circuit current rating

(SCCR) shown on the unit nameplate

Three phase voltage imbalance will cause

motor overheating and premature failure

The maximum allowable imbalance is 20

Voltage imbalance is defined as 100 times

the maximum deviation from the average

voltage divided by the average voltage

Example

(221V+230V+227V)3 = 226V then

100(226V-221V)226V = 22 which

exceeds the allowable imbalance

Check voltage imbalance at the unit

disconnect switch and at the compressor

terminal Contact your local power company

for line voltage corrections

Installing contractor must check for proper

motor rotation and check blower motor

amperage listed on the motor nameplate is

not exceeded

Wire control signals to the unitrsquos low

voltage terminal block located in the

controls compartment

If any factory installed wiring must be

replaced use a minimum 105degC type AWM

insulated conductors

Thermostat

If a thermostat is used for unit control

thermostat should be located on an inside

wall 4-5 feet above the floor where it will

not be subjected to drafts sun exposure or

heat from electrical fixtures or appliances

Follow thermostat manufacturerrsquos

instructions for general installation

procedure

Thermostat control wiring size must be large

enough to prevent excess voltage drop and

ensure proper operation

All external devices must be powered via a

separate external power supply

Units with the modulating hot gas reheat

dehumidification feature must use a

humidistat or a thermostat with a normally

closed (NC) dehumidification option The

following thermostats have been approved

for usage with the dehumidification feature

Robertshawreg 9825i2 Thermostat

Honeywell VisionPROreg IAQ Thermostat

AAON Mini Controller

Three phase voltage imbalance will cause motor overheating and premature failure

CAUTION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 4: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

4

Index of Tables and Figures

Tables Table 1 - Recommended Elevation Minimums 15 Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A 25 Table 3 - Acceptable Refrigeration Circuit Values 28

Table 4 - Performance Testing Air Flow Setpoints 29 Table 5 - R-410A Refrigerant Temperature-Pressure Chart 30 Table 6 - Demand Signal vs Compressor Capacity Modulation 32 Table 7 - Thermistor Temperature vs Resistance Values 33 Table 8 - Condenser Flooding 36

Figures Figure 1 ndash Forklift Channels amp Access Panel 14 Figure 2 ndash Condensing Unit Clearances 15 Figure 3 ndash Utility Entry 16 Figure 4 ndash Heat Pump Piping Schematic of Suction Vapor Flow Down in Double Riser 21

Figure 5 ndash Heat Pump Piping Schematic of Discharge Vapor Flow Up in Double Riser 21 Figure 6 - Riser height versus total equivalent line length 25 Figure 7 - Variable Capacity Compressor Controller 32

Figure 8 - Compressor Controller Flash Code Details 33 Figure 9 - Adjustable Fan Cycling Switch 34

Figure 10 - Piping Schematic of Example System using the LAC Valve 35 Figure 11 - Adjustable compressor lockout 36 Figure 12ndash AC only piping AHU above CU 40

Figure 13 ndash AC only piping AHU below CU 41

Figure 14 ndash Modulating hot gas reheat piping AHU above CU 42 Figure 15 ndash Modulating hot gas reheat piping AHU below CU 43 Figure 16 ndash Hot gas bypass piping AHU above CU 44

Figure 17 ndash Hot gas bypass piping AHU below CU 45 Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU 46

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU 47 Figure 20 ndash Heat pump piping AHU above CU 48 Figure 21 ndash Heat pump piping AHU below CU 49 Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU 50

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU 51

R57611 Rev A 161221

(ACP J00187)

5

AAONreg CB Series Features and Options Introduction

Energy Efficiency

Two Step or Variable Capacity Scroll

Compressor

Air-Source Heat Pump

Variable Speed Condenser Fans for Head

Pressure Control

Humidity Control

Modulating Hot Gas Reheat

Safety

Suction Pressure Transducer

Heavy Duty Wire Guards or Louvered

Panels for Condenser Coils

Automatic Low Pressure and Manual

reset High Pressure Safety Cut-outs

Suction and Liquid Line Schrader Valves

Installation and Maintenance Easily Removable Panel Access to

Service Compartment

Run Test Report and Installation Manuals

Included in Controls Compartment

Color Coded Wiring and Wiring

Diagrams

24V Control Circuit Transformer Option

System Integration

Split System Matching

Modulating Head Pressure Control

Single Point Power

High Density Foam Compressor Sound

Suppression Blanket

Environmentally Friendly

R-410A Refrigerant

Extended Life

2500 Hour Salt Spray Tested Exterior

Corrosion Paint

Optional 5 Year Non-Prorated

Compressor Warranty

Polymer E-Coated Condenser Coils

6

ELECTRIC SHOCK Electric shock hazard Before servicing shut off all electrical power to the unit including remote disconnects to avoid shock hazard or injury from rotating parts Follow proper Lockout-Tagout procedures

WARNING

Safety

Attention should be paid to the following statements

NOTE - Notes are intended to clarify the unit installation operation and maintenance

CAUTION - Caution statements are given to prevent actions that may result in

equipment damage property damage or personal injury

WARNING - Warning statements are given to prevent actions that could result in

equipment damage property damage personal injury or death

DANGER - Danger statements are given to prevent actions that will result in equipment

damage property damage severe personal injury or death

ELECTRIC SHOCK FIRE OR EXPLOSION HAZARD Failure to follow safety warnings exactly could result in dangerous operation serious injury death or property damage Improper servicing could result in dangerous operation serious injury death or property damage When servicing controls label all

wires prior to disconnecting Reconnect wires correctly

Verify proper operation after servicing Secure all doors with key-lock or nut and bolt

WARNING

QUALIFIED INSTALLER Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician A copy of this IOM should be kept with the unit

WARNING

7

FIRE EXPLOSION OR CARBON MONOXIDE POISONING HAZARD Failure to replace proper controls could result in fire explosion or carbon monoxide poisoning Failure to follow safety warnings exactly could result in serious injury death or property damage Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this appliance

WARNING

LIVE ELECTRICAL During installation testing servicing and troubleshooting of the equipment it may be necessary to work with live electrical components Only a qualified licensed electrician or individual properly trained in handling live electrical components shall perform these tasks Standard NFPA-70E an OSHA regulation requiring an Arc Flash Boundary to be field established and marked for identification of where appropriate Personal Protective Equipment (PPE) be worn should be followed

WARNING

GROUNDING REQUIRED All field installed wiring must be completed by qualified personnel Field installed wiring must comply with NECCEC local and state electrical code requirements Failure to follow code requirements could result in serious injury or death Provide proper unit ground in accordance with these code requirements

WARNING

ROTATING COMPONENTS Unit contains fans with moving parts that can cause serious injury Do not remove grill containing fans until the power to the unit has been disconnected and fan has stopped rotating

WARNING

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of 3 phase units at startup by a qualified service technician Scroll compressors are directional and can be damaged if rotated in the wrong direction Compressor rotation must be checked using suction and discharge gauges Fan motor rotation should be checked for proper operation Alterations should only be made at the unit power connection

CAUTION

8

Compartments containing hazardous voltage or rotating parts are equipped with a panel requiring tooled access Always re-install screws on the panel after installation or service is completed

CAUTION

UNIT HANDLING To prevent injury or death lifting equipment capacity shall exceed unit weight by an adequate safety factor Always test-lift unit not more than 24 inches high to verify proper center of gravity lift point to avoid unit damage injury or death

WARNING

LEAK TESTING

Do not use oxygen acetylene or air in place of refrigerant and dry nitrogen for leak testing A violent explosion may result causing injury or death

WARNING

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

COIL CLEANERS

To prevent damage to the unit do not use acidic chemical coil cleaners Do not use alkaline chemical coil cleaners with a pH value greater than 85 after mixing without first using an aluminum corrosion inhibitor in the cleaning solution

CAUTION

COIL CLEANERS

Some chemical coil cleaning compounds are caustic or toxic Use these substances only in accordance with the manufacturerrsquos usage instructions Failure to follow instructions may result in equipment damage injury or death

WARNING

9

1 Startup and service must be performed

by a Factory Trained Service

Technician

2 The unit is for outdoor use only See

General Information section for more

unit information

3 Every unit has a unique equipment

nameplate with electrical operational

and unit clearance specifications

Always refer to the unit nameplate for

specific ratings unique to the model you

have purchased

4 READ THE ENTIRE INSTALLATION

OPERATION AND MAINTENANCE

MANUAL OTHER IMPORTANT

SAFETY PRECAUTIONS ARE

PROVIDED THROUGHOUT THIS

MANUAL

5 Keep this manual and all literature

safeguarded near or on the unit

COIL CLEANING

Do not clean DX refrigerant coils with hot water or steam The use of hot water or steam on refrigerant coils will cause high pressure inside the coil tubing and damage to the coil

CAUTION

ENCLOSED AREA

Do not work in an enclosed area where refrigerant or nitrogen gases may be leaking A sufficient quantity of vapors may be present and cause

injury or death

WARNING

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

CB Series Feature String Nomenclature

Model Options Unit Feature Options

GE

N

MJ

RE

V

UN

IT

SIZ

E

VL

T

CO

MP

CK

TS

1

2

3

4

5

6

7

CB - B - 060 - 3 - B - 1 B D 0 0 D A 0

10

CB Base Model and Features Description

BASE MODEL SERIES AND GENERATION

CB

REVISION

B = Design Sequence

UNIT SIZE

024 = 24 MBH - 2 Ton - Vertical Discharge

036 = 36 MBH - 3 Ton - Vertical Discharge

048 = 48 MBH - 4 Ton - Vertical Discharge

060 = 60 MBH - 5 Ton - Vertical Discharge

VOLTAGE

1 = 230V1Φ60Hz

2 = 230V3Φ60Hz

3 = 460V3Φ60Hz

4 = 575V3Φ60Hz

8 = 208V3Φ60Hz

9 = 208V1Φ60Hz

COMPRESSOR TYPE

B = R-410A Two Step Scroll Compressor

D = R-410A Variable Capacity Scroll Compressor

F = R-410A Two Step Scroll Compressor with Sound

Blanket

H = R-410A Variable Capacity Scroll Compressor

with Sound Blanket

NUMBER OF CIRCUITS

1 = One Circuit

FEATURE 1 AMBIENT CONTROL 0 = Standard (55degF Ambient)

B = Adjustable Fan Cycling (35degF Ambient)

D = Modulating Fan Pressure Control (35degF

Ambient)

F = Flooded Condenser Ambient Controls (0degF) +

Option B

G = Flooded Condenser Ambient Controls (0degF) +

Option D

FEATURE 2 REFRIGERATION

OPTIONS 0 = Standard - Split System Air Conditioner

A = External Hot Gas Bypass

B = Split System Heat Pump

D = Modulating Hot Gas Reheat

F = Options A + D

G = Options B + D

FEATURE 3 CONTROLS

0 = Standard - Terminal Block

A = Suction Pressure Transducer (F1- Wattmaster

Reheat)

H = Control Circuit Transformer

S = Suction Pressure Transducer (Not F1 -

Wattmaster Controls)

T = Control Circuit Transformer w Suction Pressure

Transducer

FEATURE 4 COIL PROTECTION

0 = Standard

A = Polymer E-Coated Coil

FEATURE 5 CABINET OPTIONS D = Standard ndash Louvered Panels + 2500 Hour Salt-

Spray Tested Exterior Paint

G = Wire Grille + 2500 Hour Salt-Spray Tested

Exterior Paint

FEATURE 6 WARRANTY 0 = Standard

A = Second to Fifth Year Extended Compressor

Warranty

FEATURE 7 TYPE 0 = Standard

X = Special Pricing Authorization

11

General Description

AAON CB Series condensing units have

been designed for outdoor installation only

Startup and service must be performed by a

Factory Trained Service Technician

Codes and Ordinances

CB Series units have been tested and

certified by ETL in accordance with UL

Safety Standard 1995CSA C222 No 236

System should be sized in accordance with

the American Society of Heating

Refrigeration and Air Conditioning

Engineers Handbook

Installation of CB Series units must conform

to the ICC standards of the International

Mechanical Code the International Building

Code and local building plumbing and

waste water codes All appliances must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Receiving Unit

When received the unit should be checked

for damage that might have occurred in

transit If damage is found it should be noted

on the carrierrsquos Freight Bill A request for

inspection by carrierrsquos agent should be made

in writing at once

Nameplate should be checked to ensure the

correct model sizes and voltages have been

received to match the job requirements

If repairs must be made to damaged goods

then the factory should be notified before

any repair action is taken in order to protect

the warranty Certain equipment alteration

repair and manipulation of equipment

without the manufacturerrsquos consent may

void the product warranty Contact AAON

Warranty Department for assistance with

handling damaged goods repairs and

freight claims (903) 236-4403

NOTE Upon receipt check shipment for

items that ship loose Consult order and

shipment documentation to identify potential

loose-shipped items Loose-shipped items

The Clean Air Act of 1990 bans the intentional venting of refrigerant as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed

CAUTION

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a Factory Trained Service Technician

WARNING

SHARP EDGES

Coils and sheet metal surfaces present sharp edges and care must be taken when working with equipment

WARNING

Failure to observe the following instructions will result in premature failure of your system and possible voiding of the warranty

WARNING

12

may have been placed inside the unit cabinet

for security Installers and owners should

secure all doors with locks or nuts and bolts

to prevent unauthorized access

The warranty card must be completed in full

and returned to AAON not more than 3

months after the unit is delivered

Storage

If installation will not occur immediately

following delivery store equipment in a dry

protected area away from construction

traffic and in the proper orientation as

marked on the packaging with all internal

packaging in place Secure all loose-shipped

items

Direct Expansion (DX) Condensing Units

CB Series condensing units are factory

assembled and wired including a full charge

of R-410A refrigerant for up to 25 feet of

line set Systems with the modulating hot

gas reheat option will require refrigerant to

be field added because of the additional

refrigerant components and piping

associated with the system

Failure to observe the following instructions

may result in premature failure of your

system and possible voiding of the

warranty

Never cut off the main power supply to the

unit except for servicing emergency or

complete shutdown of the unit When power

is cut off from the unit compressors using

crankcase heaters cannot prevent refrigerant

migration This means the compressor may

cool down and liquid refrigerant may

accumulate in the compressor Since the

compressor is designed to pump refrigerant

gas damage may occur when power is

restored

If power to the unit must be off for more

than an hour turn the thermostat system

switch to ldquoOffrdquo or turn the unit off at the

control panel and then cut off the main

power supply Leave the unit off until the

main power supply has been turned on again

for at least 24 hours This will give the

crankcase heater time to clear any liquid

accumulation out of the compressor before it

is required to run

Always control the system from the

thermostat or control panel never at the

main power supply except for servicing

emergency or complete shutdown of the

unit

The standard compressors must be on a

minimum of 5 minutes and off for a

minimum of 5 minutes The cycle rate must

be no more than 6 starts per hour

The variable capacity compressors must be

on a minimum of 3 minutes and off for a

minimum of 3 minutes The cycle rate must

be no more than 10 starts per hour

The compressor life will be seriously

shortened by reduced lubrication and the

pumping of excessive amounts of liquid oil

and liquid refrigerant

CRANKCASE HEATER OPERATION

Units are equipped with compressor crankcase heaters which should be energized at least 24 hours prior to cooling operation to clear any liquid refrigerant from the compressors

CAUTION

13

Note Low Ambient Operation

Units without a low ambient option such as

condenser fan cycling or the 0degF low

ambient option will not operate in the

cooling mode of operation properly when

the outdoor temperature is below 55degF Low

ambient andor air handling unit economizer

options are recommended if cooling

operation below 55degF is expected

Note Multiple Systems with Multiple

Thermostats

When several heating and cooling split

systems are used to condition a space all

thermostat switches must be set in either

heating mode cooling mode or off Do not

leave part of the systems switched to the

opposite mode Cooling only systems should

be switched off at the thermostat during the

heating season

Wiring Diagrams

Unit specific wiring diagram is laminated in

plastic and located inside the controls

compartment door

General Maintenance

When the initial startup is made and on a

periodic schedule during operation it is

necessary to perform routine service checks

on the performance of the condensing unit

This includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

14

Installation

AAON equipment has been designed for

quick and easy installation

Lifting the Unit

CB Series condensing units have channels

underneath the base which provide lifting

access to the underside of the equipment and

allow moving and placement without

physical damage

Figure 1 ndash Forklift Channels amp Access Panel

Dollies andor carts are recommended to lift

and place the unit to prevent damage to the

equipment and injury to the installer

Care should be taken if using spreader bars

blocking or other lifting devices to prevent

any damage to the cabinet coil or

condensing fans

Before lifting unit be sure that all shipping

material has been removed from unit

Hoist unit to a point directly above the

condenser pad and lower unit into the

proper place Unit may also be positioned

with a dolly When the unit is in place

remove the dolly or lifting device Make

sure the unit is properly seated and level

Locating Unit

CB Series condensing units are designed for

outdoor application and placement at ground

level or on a rooftop Units must be placed

on a level and solid foundation that can

support the unitrsquos weight

When rooftop mounted a steel frame must

be provided that will support the unit above

the roof itself for load distribution

When installed at ground level a one-piece

concrete slab or composite condenser pad

should be used with footings that extend

below the frost line (a substantial base that

will not settle) Slab should be surrounded

by a graveled area for proper drainage and

should not adjoin the building as sound and

vibration may be transmitted to the

structure Care must also be taken to protect

the coils and fins from damage due to

vandalism or other hazards

Airflow to and from the condensing unit

must not be restricted Coils and fans must

be free of any obstructions and debris in

order to start and operate properly with a

correct amount of airflow Obstruction to air

flow will result in decreased performance

and efficiency

The installation position must provide at

least one foot of clearance from the wall for

proper air flow to the coils When multiple

units are mounted adjacent to each other the

clearance required between them is three

feet

Service compartment must be accessible for

periodic servicing of controls safety

devices and refrigerant serviceshutoff

valves At least two feet of clearance on this

Incorrect lifting can cause damage to the unit

CAUTION

15

corner of the unit is recommended for

service

Figure 2 ndash Condensing Unit Clearances

Condensing units should not be installed in

an enclosure or pit that is deeper than the

height of the unit When recessed

installation is necessary the clearance to

maintain proper airflow is at least three feet

CB Series condensing units are single

circuited with vertical air discharge There

must be no obstruction above the equipment

Do not place the unit under an overhang

Placement relative to the building air intakes

and other structures must be carefully

selected Consider the effects of outdoor fan

noise on conditioned space and any adjacent

occupied space It is recommended that the

unit be placed so that discharge does not

blow toward windows less than 25 feet

away

Heat pumps require special location

consideration in areas where snow

accumulation can become an obstruction

and in areas with prolonged continuous

subfreezing temperatures Heat pump unit

bases are cutout under the outdoor coil to

permit drainage of frost accumulation The

unit must be situated to permit free

unobstructed drainage of the defrost water

and ice A minimum 3 inches clearance

under the outdoor coil is required in the

milder climates In more severe weather

locations it is recommended that the unit be

elevated to allow unobstructed drainage and

airflow

Table 1 - Recommended Elevation

Minimums

Design

Temperature

Suggest Minimum

Elevation

+15 F and above 3rdquo

-5 F to +17 F 8rdquo

Below -5 F 12rdquo

Mounting Isolation

For roof mounted applications or anytime

vibration transmission is a factor vibration

isolators may be used

Access Panel

Access panel is provided to electrical

compartment To remove the panel

unscrew the four screws

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

16

Electrical

Verify the unit nameplate agrees with the

power supply Connect power and control

field wiring as shown on the unit wiring

diagram provided with the unit

Route power and control wiring separately

through the utility entry right above the

service valves Do not run power and signal

wires in the same conduit

Figure 3 ndash Utility Entry

Size supply conductors based on the unit

MCA rating Supply conductors must be

rated a minimum of 75degC

Protect the branch circuit in accordance with

code requirements The unit must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Note Units are factory wired for 208V

230V 460V or 575V In some units the

208V and 230V options may also be

provided in single or three phase

configurations The transformer

configuration must be checked by a

qualified technician prior to startup

Wire power leads to the unit terminal block

All wiring beyond this point has been done

by the manufacturer and cannot be modified

without affecting the units agencysafety

certification

All units require field supplied electrical

overcurrent and short circuit protection

Device must not be sized larger than the

Maximum Overcurrent Protection (MOP)

shown on the unit nameplate

Codes may require a disconnect switch be

within sight of the unit

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Before attempting to perform any installation service or maintenance shut off all electrical power to the unit at the disconnect switches Unit may have multiple power supplies Failure to disconnect power could result in dangerous operation serious injury death or property damage

WARNING

17

It is recommended that the field installed

overcurrent protection or disconnect switch

not be installed on the unit

Supply voltage must be within the minmax

range shown on the unit nameplate

Available short circuit current should not

exceed the short circuit current rating

(SCCR) shown on the unit nameplate

Three phase voltage imbalance will cause

motor overheating and premature failure

The maximum allowable imbalance is 20

Voltage imbalance is defined as 100 times

the maximum deviation from the average

voltage divided by the average voltage

Example

(221V+230V+227V)3 = 226V then

100(226V-221V)226V = 22 which

exceeds the allowable imbalance

Check voltage imbalance at the unit

disconnect switch and at the compressor

terminal Contact your local power company

for line voltage corrections

Installing contractor must check for proper

motor rotation and check blower motor

amperage listed on the motor nameplate is

not exceeded

Wire control signals to the unitrsquos low

voltage terminal block located in the

controls compartment

If any factory installed wiring must be

replaced use a minimum 105degC type AWM

insulated conductors

Thermostat

If a thermostat is used for unit control

thermostat should be located on an inside

wall 4-5 feet above the floor where it will

not be subjected to drafts sun exposure or

heat from electrical fixtures or appliances

Follow thermostat manufacturerrsquos

instructions for general installation

procedure

Thermostat control wiring size must be large

enough to prevent excess voltage drop and

ensure proper operation

All external devices must be powered via a

separate external power supply

Units with the modulating hot gas reheat

dehumidification feature must use a

humidistat or a thermostat with a normally

closed (NC) dehumidification option The

following thermostats have been approved

for usage with the dehumidification feature

Robertshawreg 9825i2 Thermostat

Honeywell VisionPROreg IAQ Thermostat

AAON Mini Controller

Three phase voltage imbalance will cause motor overheating and premature failure

CAUTION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 5: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

5

AAONreg CB Series Features and Options Introduction

Energy Efficiency

Two Step or Variable Capacity Scroll

Compressor

Air-Source Heat Pump

Variable Speed Condenser Fans for Head

Pressure Control

Humidity Control

Modulating Hot Gas Reheat

Safety

Suction Pressure Transducer

Heavy Duty Wire Guards or Louvered

Panels for Condenser Coils

Automatic Low Pressure and Manual

reset High Pressure Safety Cut-outs

Suction and Liquid Line Schrader Valves

Installation and Maintenance Easily Removable Panel Access to

Service Compartment

Run Test Report and Installation Manuals

Included in Controls Compartment

Color Coded Wiring and Wiring

Diagrams

24V Control Circuit Transformer Option

System Integration

Split System Matching

Modulating Head Pressure Control

Single Point Power

High Density Foam Compressor Sound

Suppression Blanket

Environmentally Friendly

R-410A Refrigerant

Extended Life

2500 Hour Salt Spray Tested Exterior

Corrosion Paint

Optional 5 Year Non-Prorated

Compressor Warranty

Polymer E-Coated Condenser Coils

6

ELECTRIC SHOCK Electric shock hazard Before servicing shut off all electrical power to the unit including remote disconnects to avoid shock hazard or injury from rotating parts Follow proper Lockout-Tagout procedures

WARNING

Safety

Attention should be paid to the following statements

NOTE - Notes are intended to clarify the unit installation operation and maintenance

CAUTION - Caution statements are given to prevent actions that may result in

equipment damage property damage or personal injury

WARNING - Warning statements are given to prevent actions that could result in

equipment damage property damage personal injury or death

DANGER - Danger statements are given to prevent actions that will result in equipment

damage property damage severe personal injury or death

ELECTRIC SHOCK FIRE OR EXPLOSION HAZARD Failure to follow safety warnings exactly could result in dangerous operation serious injury death or property damage Improper servicing could result in dangerous operation serious injury death or property damage When servicing controls label all

wires prior to disconnecting Reconnect wires correctly

Verify proper operation after servicing Secure all doors with key-lock or nut and bolt

WARNING

QUALIFIED INSTALLER Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician A copy of this IOM should be kept with the unit

WARNING

7

FIRE EXPLOSION OR CARBON MONOXIDE POISONING HAZARD Failure to replace proper controls could result in fire explosion or carbon monoxide poisoning Failure to follow safety warnings exactly could result in serious injury death or property damage Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this appliance

WARNING

LIVE ELECTRICAL During installation testing servicing and troubleshooting of the equipment it may be necessary to work with live electrical components Only a qualified licensed electrician or individual properly trained in handling live electrical components shall perform these tasks Standard NFPA-70E an OSHA regulation requiring an Arc Flash Boundary to be field established and marked for identification of where appropriate Personal Protective Equipment (PPE) be worn should be followed

WARNING

GROUNDING REQUIRED All field installed wiring must be completed by qualified personnel Field installed wiring must comply with NECCEC local and state electrical code requirements Failure to follow code requirements could result in serious injury or death Provide proper unit ground in accordance with these code requirements

WARNING

ROTATING COMPONENTS Unit contains fans with moving parts that can cause serious injury Do not remove grill containing fans until the power to the unit has been disconnected and fan has stopped rotating

WARNING

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of 3 phase units at startup by a qualified service technician Scroll compressors are directional and can be damaged if rotated in the wrong direction Compressor rotation must be checked using suction and discharge gauges Fan motor rotation should be checked for proper operation Alterations should only be made at the unit power connection

CAUTION

8

Compartments containing hazardous voltage or rotating parts are equipped with a panel requiring tooled access Always re-install screws on the panel after installation or service is completed

CAUTION

UNIT HANDLING To prevent injury or death lifting equipment capacity shall exceed unit weight by an adequate safety factor Always test-lift unit not more than 24 inches high to verify proper center of gravity lift point to avoid unit damage injury or death

WARNING

LEAK TESTING

Do not use oxygen acetylene or air in place of refrigerant and dry nitrogen for leak testing A violent explosion may result causing injury or death

WARNING

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

COIL CLEANERS

To prevent damage to the unit do not use acidic chemical coil cleaners Do not use alkaline chemical coil cleaners with a pH value greater than 85 after mixing without first using an aluminum corrosion inhibitor in the cleaning solution

CAUTION

COIL CLEANERS

Some chemical coil cleaning compounds are caustic or toxic Use these substances only in accordance with the manufacturerrsquos usage instructions Failure to follow instructions may result in equipment damage injury or death

WARNING

9

1 Startup and service must be performed

by a Factory Trained Service

Technician

2 The unit is for outdoor use only See

General Information section for more

unit information

3 Every unit has a unique equipment

nameplate with electrical operational

and unit clearance specifications

Always refer to the unit nameplate for

specific ratings unique to the model you

have purchased

4 READ THE ENTIRE INSTALLATION

OPERATION AND MAINTENANCE

MANUAL OTHER IMPORTANT

SAFETY PRECAUTIONS ARE

PROVIDED THROUGHOUT THIS

MANUAL

5 Keep this manual and all literature

safeguarded near or on the unit

COIL CLEANING

Do not clean DX refrigerant coils with hot water or steam The use of hot water or steam on refrigerant coils will cause high pressure inside the coil tubing and damage to the coil

CAUTION

ENCLOSED AREA

Do not work in an enclosed area where refrigerant or nitrogen gases may be leaking A sufficient quantity of vapors may be present and cause

injury or death

WARNING

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

CB Series Feature String Nomenclature

Model Options Unit Feature Options

GE

N

MJ

RE

V

UN

IT

SIZ

E

VL

T

CO

MP

CK

TS

1

2

3

4

5

6

7

CB - B - 060 - 3 - B - 1 B D 0 0 D A 0

10

CB Base Model and Features Description

BASE MODEL SERIES AND GENERATION

CB

REVISION

B = Design Sequence

UNIT SIZE

024 = 24 MBH - 2 Ton - Vertical Discharge

036 = 36 MBH - 3 Ton - Vertical Discharge

048 = 48 MBH - 4 Ton - Vertical Discharge

060 = 60 MBH - 5 Ton - Vertical Discharge

VOLTAGE

1 = 230V1Φ60Hz

2 = 230V3Φ60Hz

3 = 460V3Φ60Hz

4 = 575V3Φ60Hz

8 = 208V3Φ60Hz

9 = 208V1Φ60Hz

COMPRESSOR TYPE

B = R-410A Two Step Scroll Compressor

D = R-410A Variable Capacity Scroll Compressor

F = R-410A Two Step Scroll Compressor with Sound

Blanket

H = R-410A Variable Capacity Scroll Compressor

with Sound Blanket

NUMBER OF CIRCUITS

1 = One Circuit

FEATURE 1 AMBIENT CONTROL 0 = Standard (55degF Ambient)

B = Adjustable Fan Cycling (35degF Ambient)

D = Modulating Fan Pressure Control (35degF

Ambient)

F = Flooded Condenser Ambient Controls (0degF) +

Option B

G = Flooded Condenser Ambient Controls (0degF) +

Option D

FEATURE 2 REFRIGERATION

OPTIONS 0 = Standard - Split System Air Conditioner

A = External Hot Gas Bypass

B = Split System Heat Pump

D = Modulating Hot Gas Reheat

F = Options A + D

G = Options B + D

FEATURE 3 CONTROLS

0 = Standard - Terminal Block

A = Suction Pressure Transducer (F1- Wattmaster

Reheat)

H = Control Circuit Transformer

S = Suction Pressure Transducer (Not F1 -

Wattmaster Controls)

T = Control Circuit Transformer w Suction Pressure

Transducer

FEATURE 4 COIL PROTECTION

0 = Standard

A = Polymer E-Coated Coil

FEATURE 5 CABINET OPTIONS D = Standard ndash Louvered Panels + 2500 Hour Salt-

Spray Tested Exterior Paint

G = Wire Grille + 2500 Hour Salt-Spray Tested

Exterior Paint

FEATURE 6 WARRANTY 0 = Standard

A = Second to Fifth Year Extended Compressor

Warranty

FEATURE 7 TYPE 0 = Standard

X = Special Pricing Authorization

11

General Description

AAON CB Series condensing units have

been designed for outdoor installation only

Startup and service must be performed by a

Factory Trained Service Technician

Codes and Ordinances

CB Series units have been tested and

certified by ETL in accordance with UL

Safety Standard 1995CSA C222 No 236

System should be sized in accordance with

the American Society of Heating

Refrigeration and Air Conditioning

Engineers Handbook

Installation of CB Series units must conform

to the ICC standards of the International

Mechanical Code the International Building

Code and local building plumbing and

waste water codes All appliances must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Receiving Unit

When received the unit should be checked

for damage that might have occurred in

transit If damage is found it should be noted

on the carrierrsquos Freight Bill A request for

inspection by carrierrsquos agent should be made

in writing at once

Nameplate should be checked to ensure the

correct model sizes and voltages have been

received to match the job requirements

If repairs must be made to damaged goods

then the factory should be notified before

any repair action is taken in order to protect

the warranty Certain equipment alteration

repair and manipulation of equipment

without the manufacturerrsquos consent may

void the product warranty Contact AAON

Warranty Department for assistance with

handling damaged goods repairs and

freight claims (903) 236-4403

NOTE Upon receipt check shipment for

items that ship loose Consult order and

shipment documentation to identify potential

loose-shipped items Loose-shipped items

The Clean Air Act of 1990 bans the intentional venting of refrigerant as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed

CAUTION

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a Factory Trained Service Technician

WARNING

SHARP EDGES

Coils and sheet metal surfaces present sharp edges and care must be taken when working with equipment

WARNING

Failure to observe the following instructions will result in premature failure of your system and possible voiding of the warranty

WARNING

12

may have been placed inside the unit cabinet

for security Installers and owners should

secure all doors with locks or nuts and bolts

to prevent unauthorized access

The warranty card must be completed in full

and returned to AAON not more than 3

months after the unit is delivered

Storage

If installation will not occur immediately

following delivery store equipment in a dry

protected area away from construction

traffic and in the proper orientation as

marked on the packaging with all internal

packaging in place Secure all loose-shipped

items

Direct Expansion (DX) Condensing Units

CB Series condensing units are factory

assembled and wired including a full charge

of R-410A refrigerant for up to 25 feet of

line set Systems with the modulating hot

gas reheat option will require refrigerant to

be field added because of the additional

refrigerant components and piping

associated with the system

Failure to observe the following instructions

may result in premature failure of your

system and possible voiding of the

warranty

Never cut off the main power supply to the

unit except for servicing emergency or

complete shutdown of the unit When power

is cut off from the unit compressors using

crankcase heaters cannot prevent refrigerant

migration This means the compressor may

cool down and liquid refrigerant may

accumulate in the compressor Since the

compressor is designed to pump refrigerant

gas damage may occur when power is

restored

If power to the unit must be off for more

than an hour turn the thermostat system

switch to ldquoOffrdquo or turn the unit off at the

control panel and then cut off the main

power supply Leave the unit off until the

main power supply has been turned on again

for at least 24 hours This will give the

crankcase heater time to clear any liquid

accumulation out of the compressor before it

is required to run

Always control the system from the

thermostat or control panel never at the

main power supply except for servicing

emergency or complete shutdown of the

unit

The standard compressors must be on a

minimum of 5 minutes and off for a

minimum of 5 minutes The cycle rate must

be no more than 6 starts per hour

The variable capacity compressors must be

on a minimum of 3 minutes and off for a

minimum of 3 minutes The cycle rate must

be no more than 10 starts per hour

The compressor life will be seriously

shortened by reduced lubrication and the

pumping of excessive amounts of liquid oil

and liquid refrigerant

CRANKCASE HEATER OPERATION

Units are equipped with compressor crankcase heaters which should be energized at least 24 hours prior to cooling operation to clear any liquid refrigerant from the compressors

CAUTION

13

Note Low Ambient Operation

Units without a low ambient option such as

condenser fan cycling or the 0degF low

ambient option will not operate in the

cooling mode of operation properly when

the outdoor temperature is below 55degF Low

ambient andor air handling unit economizer

options are recommended if cooling

operation below 55degF is expected

Note Multiple Systems with Multiple

Thermostats

When several heating and cooling split

systems are used to condition a space all

thermostat switches must be set in either

heating mode cooling mode or off Do not

leave part of the systems switched to the

opposite mode Cooling only systems should

be switched off at the thermostat during the

heating season

Wiring Diagrams

Unit specific wiring diagram is laminated in

plastic and located inside the controls

compartment door

General Maintenance

When the initial startup is made and on a

periodic schedule during operation it is

necessary to perform routine service checks

on the performance of the condensing unit

This includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

14

Installation

AAON equipment has been designed for

quick and easy installation

Lifting the Unit

CB Series condensing units have channels

underneath the base which provide lifting

access to the underside of the equipment and

allow moving and placement without

physical damage

Figure 1 ndash Forklift Channels amp Access Panel

Dollies andor carts are recommended to lift

and place the unit to prevent damage to the

equipment and injury to the installer

Care should be taken if using spreader bars

blocking or other lifting devices to prevent

any damage to the cabinet coil or

condensing fans

Before lifting unit be sure that all shipping

material has been removed from unit

Hoist unit to a point directly above the

condenser pad and lower unit into the

proper place Unit may also be positioned

with a dolly When the unit is in place

remove the dolly or lifting device Make

sure the unit is properly seated and level

Locating Unit

CB Series condensing units are designed for

outdoor application and placement at ground

level or on a rooftop Units must be placed

on a level and solid foundation that can

support the unitrsquos weight

When rooftop mounted a steel frame must

be provided that will support the unit above

the roof itself for load distribution

When installed at ground level a one-piece

concrete slab or composite condenser pad

should be used with footings that extend

below the frost line (a substantial base that

will not settle) Slab should be surrounded

by a graveled area for proper drainage and

should not adjoin the building as sound and

vibration may be transmitted to the

structure Care must also be taken to protect

the coils and fins from damage due to

vandalism or other hazards

Airflow to and from the condensing unit

must not be restricted Coils and fans must

be free of any obstructions and debris in

order to start and operate properly with a

correct amount of airflow Obstruction to air

flow will result in decreased performance

and efficiency

The installation position must provide at

least one foot of clearance from the wall for

proper air flow to the coils When multiple

units are mounted adjacent to each other the

clearance required between them is three

feet

Service compartment must be accessible for

periodic servicing of controls safety

devices and refrigerant serviceshutoff

valves At least two feet of clearance on this

Incorrect lifting can cause damage to the unit

CAUTION

15

corner of the unit is recommended for

service

Figure 2 ndash Condensing Unit Clearances

Condensing units should not be installed in

an enclosure or pit that is deeper than the

height of the unit When recessed

installation is necessary the clearance to

maintain proper airflow is at least three feet

CB Series condensing units are single

circuited with vertical air discharge There

must be no obstruction above the equipment

Do not place the unit under an overhang

Placement relative to the building air intakes

and other structures must be carefully

selected Consider the effects of outdoor fan

noise on conditioned space and any adjacent

occupied space It is recommended that the

unit be placed so that discharge does not

blow toward windows less than 25 feet

away

Heat pumps require special location

consideration in areas where snow

accumulation can become an obstruction

and in areas with prolonged continuous

subfreezing temperatures Heat pump unit

bases are cutout under the outdoor coil to

permit drainage of frost accumulation The

unit must be situated to permit free

unobstructed drainage of the defrost water

and ice A minimum 3 inches clearance

under the outdoor coil is required in the

milder climates In more severe weather

locations it is recommended that the unit be

elevated to allow unobstructed drainage and

airflow

Table 1 - Recommended Elevation

Minimums

Design

Temperature

Suggest Minimum

Elevation

+15 F and above 3rdquo

-5 F to +17 F 8rdquo

Below -5 F 12rdquo

Mounting Isolation

For roof mounted applications or anytime

vibration transmission is a factor vibration

isolators may be used

Access Panel

Access panel is provided to electrical

compartment To remove the panel

unscrew the four screws

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

16

Electrical

Verify the unit nameplate agrees with the

power supply Connect power and control

field wiring as shown on the unit wiring

diagram provided with the unit

Route power and control wiring separately

through the utility entry right above the

service valves Do not run power and signal

wires in the same conduit

Figure 3 ndash Utility Entry

Size supply conductors based on the unit

MCA rating Supply conductors must be

rated a minimum of 75degC

Protect the branch circuit in accordance with

code requirements The unit must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Note Units are factory wired for 208V

230V 460V or 575V In some units the

208V and 230V options may also be

provided in single or three phase

configurations The transformer

configuration must be checked by a

qualified technician prior to startup

Wire power leads to the unit terminal block

All wiring beyond this point has been done

by the manufacturer and cannot be modified

without affecting the units agencysafety

certification

All units require field supplied electrical

overcurrent and short circuit protection

Device must not be sized larger than the

Maximum Overcurrent Protection (MOP)

shown on the unit nameplate

Codes may require a disconnect switch be

within sight of the unit

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Before attempting to perform any installation service or maintenance shut off all electrical power to the unit at the disconnect switches Unit may have multiple power supplies Failure to disconnect power could result in dangerous operation serious injury death or property damage

WARNING

17

It is recommended that the field installed

overcurrent protection or disconnect switch

not be installed on the unit

Supply voltage must be within the minmax

range shown on the unit nameplate

Available short circuit current should not

exceed the short circuit current rating

(SCCR) shown on the unit nameplate

Three phase voltage imbalance will cause

motor overheating and premature failure

The maximum allowable imbalance is 20

Voltage imbalance is defined as 100 times

the maximum deviation from the average

voltage divided by the average voltage

Example

(221V+230V+227V)3 = 226V then

100(226V-221V)226V = 22 which

exceeds the allowable imbalance

Check voltage imbalance at the unit

disconnect switch and at the compressor

terminal Contact your local power company

for line voltage corrections

Installing contractor must check for proper

motor rotation and check blower motor

amperage listed on the motor nameplate is

not exceeded

Wire control signals to the unitrsquos low

voltage terminal block located in the

controls compartment

If any factory installed wiring must be

replaced use a minimum 105degC type AWM

insulated conductors

Thermostat

If a thermostat is used for unit control

thermostat should be located on an inside

wall 4-5 feet above the floor where it will

not be subjected to drafts sun exposure or

heat from electrical fixtures or appliances

Follow thermostat manufacturerrsquos

instructions for general installation

procedure

Thermostat control wiring size must be large

enough to prevent excess voltage drop and

ensure proper operation

All external devices must be powered via a

separate external power supply

Units with the modulating hot gas reheat

dehumidification feature must use a

humidistat or a thermostat with a normally

closed (NC) dehumidification option The

following thermostats have been approved

for usage with the dehumidification feature

Robertshawreg 9825i2 Thermostat

Honeywell VisionPROreg IAQ Thermostat

AAON Mini Controller

Three phase voltage imbalance will cause motor overheating and premature failure

CAUTION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 6: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

6

ELECTRIC SHOCK Electric shock hazard Before servicing shut off all electrical power to the unit including remote disconnects to avoid shock hazard or injury from rotating parts Follow proper Lockout-Tagout procedures

WARNING

Safety

Attention should be paid to the following statements

NOTE - Notes are intended to clarify the unit installation operation and maintenance

CAUTION - Caution statements are given to prevent actions that may result in

equipment damage property damage or personal injury

WARNING - Warning statements are given to prevent actions that could result in

equipment damage property damage personal injury or death

DANGER - Danger statements are given to prevent actions that will result in equipment

damage property damage severe personal injury or death

ELECTRIC SHOCK FIRE OR EXPLOSION HAZARD Failure to follow safety warnings exactly could result in dangerous operation serious injury death or property damage Improper servicing could result in dangerous operation serious injury death or property damage When servicing controls label all

wires prior to disconnecting Reconnect wires correctly

Verify proper operation after servicing Secure all doors with key-lock or nut and bolt

WARNING

QUALIFIED INSTALLER Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician A copy of this IOM should be kept with the unit

WARNING

7

FIRE EXPLOSION OR CARBON MONOXIDE POISONING HAZARD Failure to replace proper controls could result in fire explosion or carbon monoxide poisoning Failure to follow safety warnings exactly could result in serious injury death or property damage Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this appliance

WARNING

LIVE ELECTRICAL During installation testing servicing and troubleshooting of the equipment it may be necessary to work with live electrical components Only a qualified licensed electrician or individual properly trained in handling live electrical components shall perform these tasks Standard NFPA-70E an OSHA regulation requiring an Arc Flash Boundary to be field established and marked for identification of where appropriate Personal Protective Equipment (PPE) be worn should be followed

WARNING

GROUNDING REQUIRED All field installed wiring must be completed by qualified personnel Field installed wiring must comply with NECCEC local and state electrical code requirements Failure to follow code requirements could result in serious injury or death Provide proper unit ground in accordance with these code requirements

WARNING

ROTATING COMPONENTS Unit contains fans with moving parts that can cause serious injury Do not remove grill containing fans until the power to the unit has been disconnected and fan has stopped rotating

WARNING

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of 3 phase units at startup by a qualified service technician Scroll compressors are directional and can be damaged if rotated in the wrong direction Compressor rotation must be checked using suction and discharge gauges Fan motor rotation should be checked for proper operation Alterations should only be made at the unit power connection

CAUTION

8

Compartments containing hazardous voltage or rotating parts are equipped with a panel requiring tooled access Always re-install screws on the panel after installation or service is completed

CAUTION

UNIT HANDLING To prevent injury or death lifting equipment capacity shall exceed unit weight by an adequate safety factor Always test-lift unit not more than 24 inches high to verify proper center of gravity lift point to avoid unit damage injury or death

WARNING

LEAK TESTING

Do not use oxygen acetylene or air in place of refrigerant and dry nitrogen for leak testing A violent explosion may result causing injury or death

WARNING

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

COIL CLEANERS

To prevent damage to the unit do not use acidic chemical coil cleaners Do not use alkaline chemical coil cleaners with a pH value greater than 85 after mixing without first using an aluminum corrosion inhibitor in the cleaning solution

CAUTION

COIL CLEANERS

Some chemical coil cleaning compounds are caustic or toxic Use these substances only in accordance with the manufacturerrsquos usage instructions Failure to follow instructions may result in equipment damage injury or death

WARNING

9

1 Startup and service must be performed

by a Factory Trained Service

Technician

2 The unit is for outdoor use only See

General Information section for more

unit information

3 Every unit has a unique equipment

nameplate with electrical operational

and unit clearance specifications

Always refer to the unit nameplate for

specific ratings unique to the model you

have purchased

4 READ THE ENTIRE INSTALLATION

OPERATION AND MAINTENANCE

MANUAL OTHER IMPORTANT

SAFETY PRECAUTIONS ARE

PROVIDED THROUGHOUT THIS

MANUAL

5 Keep this manual and all literature

safeguarded near or on the unit

COIL CLEANING

Do not clean DX refrigerant coils with hot water or steam The use of hot water or steam on refrigerant coils will cause high pressure inside the coil tubing and damage to the coil

CAUTION

ENCLOSED AREA

Do not work in an enclosed area where refrigerant or nitrogen gases may be leaking A sufficient quantity of vapors may be present and cause

injury or death

WARNING

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

CB Series Feature String Nomenclature

Model Options Unit Feature Options

GE

N

MJ

RE

V

UN

IT

SIZ

E

VL

T

CO

MP

CK

TS

1

2

3

4

5

6

7

CB - B - 060 - 3 - B - 1 B D 0 0 D A 0

10

CB Base Model and Features Description

BASE MODEL SERIES AND GENERATION

CB

REVISION

B = Design Sequence

UNIT SIZE

024 = 24 MBH - 2 Ton - Vertical Discharge

036 = 36 MBH - 3 Ton - Vertical Discharge

048 = 48 MBH - 4 Ton - Vertical Discharge

060 = 60 MBH - 5 Ton - Vertical Discharge

VOLTAGE

1 = 230V1Φ60Hz

2 = 230V3Φ60Hz

3 = 460V3Φ60Hz

4 = 575V3Φ60Hz

8 = 208V3Φ60Hz

9 = 208V1Φ60Hz

COMPRESSOR TYPE

B = R-410A Two Step Scroll Compressor

D = R-410A Variable Capacity Scroll Compressor

F = R-410A Two Step Scroll Compressor with Sound

Blanket

H = R-410A Variable Capacity Scroll Compressor

with Sound Blanket

NUMBER OF CIRCUITS

1 = One Circuit

FEATURE 1 AMBIENT CONTROL 0 = Standard (55degF Ambient)

B = Adjustable Fan Cycling (35degF Ambient)

D = Modulating Fan Pressure Control (35degF

Ambient)

F = Flooded Condenser Ambient Controls (0degF) +

Option B

G = Flooded Condenser Ambient Controls (0degF) +

Option D

FEATURE 2 REFRIGERATION

OPTIONS 0 = Standard - Split System Air Conditioner

A = External Hot Gas Bypass

B = Split System Heat Pump

D = Modulating Hot Gas Reheat

F = Options A + D

G = Options B + D

FEATURE 3 CONTROLS

0 = Standard - Terminal Block

A = Suction Pressure Transducer (F1- Wattmaster

Reheat)

H = Control Circuit Transformer

S = Suction Pressure Transducer (Not F1 -

Wattmaster Controls)

T = Control Circuit Transformer w Suction Pressure

Transducer

FEATURE 4 COIL PROTECTION

0 = Standard

A = Polymer E-Coated Coil

FEATURE 5 CABINET OPTIONS D = Standard ndash Louvered Panels + 2500 Hour Salt-

Spray Tested Exterior Paint

G = Wire Grille + 2500 Hour Salt-Spray Tested

Exterior Paint

FEATURE 6 WARRANTY 0 = Standard

A = Second to Fifth Year Extended Compressor

Warranty

FEATURE 7 TYPE 0 = Standard

X = Special Pricing Authorization

11

General Description

AAON CB Series condensing units have

been designed for outdoor installation only

Startup and service must be performed by a

Factory Trained Service Technician

Codes and Ordinances

CB Series units have been tested and

certified by ETL in accordance with UL

Safety Standard 1995CSA C222 No 236

System should be sized in accordance with

the American Society of Heating

Refrigeration and Air Conditioning

Engineers Handbook

Installation of CB Series units must conform

to the ICC standards of the International

Mechanical Code the International Building

Code and local building plumbing and

waste water codes All appliances must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Receiving Unit

When received the unit should be checked

for damage that might have occurred in

transit If damage is found it should be noted

on the carrierrsquos Freight Bill A request for

inspection by carrierrsquos agent should be made

in writing at once

Nameplate should be checked to ensure the

correct model sizes and voltages have been

received to match the job requirements

If repairs must be made to damaged goods

then the factory should be notified before

any repair action is taken in order to protect

the warranty Certain equipment alteration

repair and manipulation of equipment

without the manufacturerrsquos consent may

void the product warranty Contact AAON

Warranty Department for assistance with

handling damaged goods repairs and

freight claims (903) 236-4403

NOTE Upon receipt check shipment for

items that ship loose Consult order and

shipment documentation to identify potential

loose-shipped items Loose-shipped items

The Clean Air Act of 1990 bans the intentional venting of refrigerant as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed

CAUTION

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a Factory Trained Service Technician

WARNING

SHARP EDGES

Coils and sheet metal surfaces present sharp edges and care must be taken when working with equipment

WARNING

Failure to observe the following instructions will result in premature failure of your system and possible voiding of the warranty

WARNING

12

may have been placed inside the unit cabinet

for security Installers and owners should

secure all doors with locks or nuts and bolts

to prevent unauthorized access

The warranty card must be completed in full

and returned to AAON not more than 3

months after the unit is delivered

Storage

If installation will not occur immediately

following delivery store equipment in a dry

protected area away from construction

traffic and in the proper orientation as

marked on the packaging with all internal

packaging in place Secure all loose-shipped

items

Direct Expansion (DX) Condensing Units

CB Series condensing units are factory

assembled and wired including a full charge

of R-410A refrigerant for up to 25 feet of

line set Systems with the modulating hot

gas reheat option will require refrigerant to

be field added because of the additional

refrigerant components and piping

associated with the system

Failure to observe the following instructions

may result in premature failure of your

system and possible voiding of the

warranty

Never cut off the main power supply to the

unit except for servicing emergency or

complete shutdown of the unit When power

is cut off from the unit compressors using

crankcase heaters cannot prevent refrigerant

migration This means the compressor may

cool down and liquid refrigerant may

accumulate in the compressor Since the

compressor is designed to pump refrigerant

gas damage may occur when power is

restored

If power to the unit must be off for more

than an hour turn the thermostat system

switch to ldquoOffrdquo or turn the unit off at the

control panel and then cut off the main

power supply Leave the unit off until the

main power supply has been turned on again

for at least 24 hours This will give the

crankcase heater time to clear any liquid

accumulation out of the compressor before it

is required to run

Always control the system from the

thermostat or control panel never at the

main power supply except for servicing

emergency or complete shutdown of the

unit

The standard compressors must be on a

minimum of 5 minutes and off for a

minimum of 5 minutes The cycle rate must

be no more than 6 starts per hour

The variable capacity compressors must be

on a minimum of 3 minutes and off for a

minimum of 3 minutes The cycle rate must

be no more than 10 starts per hour

The compressor life will be seriously

shortened by reduced lubrication and the

pumping of excessive amounts of liquid oil

and liquid refrigerant

CRANKCASE HEATER OPERATION

Units are equipped with compressor crankcase heaters which should be energized at least 24 hours prior to cooling operation to clear any liquid refrigerant from the compressors

CAUTION

13

Note Low Ambient Operation

Units without a low ambient option such as

condenser fan cycling or the 0degF low

ambient option will not operate in the

cooling mode of operation properly when

the outdoor temperature is below 55degF Low

ambient andor air handling unit economizer

options are recommended if cooling

operation below 55degF is expected

Note Multiple Systems with Multiple

Thermostats

When several heating and cooling split

systems are used to condition a space all

thermostat switches must be set in either

heating mode cooling mode or off Do not

leave part of the systems switched to the

opposite mode Cooling only systems should

be switched off at the thermostat during the

heating season

Wiring Diagrams

Unit specific wiring diagram is laminated in

plastic and located inside the controls

compartment door

General Maintenance

When the initial startup is made and on a

periodic schedule during operation it is

necessary to perform routine service checks

on the performance of the condensing unit

This includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

14

Installation

AAON equipment has been designed for

quick and easy installation

Lifting the Unit

CB Series condensing units have channels

underneath the base which provide lifting

access to the underside of the equipment and

allow moving and placement without

physical damage

Figure 1 ndash Forklift Channels amp Access Panel

Dollies andor carts are recommended to lift

and place the unit to prevent damage to the

equipment and injury to the installer

Care should be taken if using spreader bars

blocking or other lifting devices to prevent

any damage to the cabinet coil or

condensing fans

Before lifting unit be sure that all shipping

material has been removed from unit

Hoist unit to a point directly above the

condenser pad and lower unit into the

proper place Unit may also be positioned

with a dolly When the unit is in place

remove the dolly or lifting device Make

sure the unit is properly seated and level

Locating Unit

CB Series condensing units are designed for

outdoor application and placement at ground

level or on a rooftop Units must be placed

on a level and solid foundation that can

support the unitrsquos weight

When rooftop mounted a steel frame must

be provided that will support the unit above

the roof itself for load distribution

When installed at ground level a one-piece

concrete slab or composite condenser pad

should be used with footings that extend

below the frost line (a substantial base that

will not settle) Slab should be surrounded

by a graveled area for proper drainage and

should not adjoin the building as sound and

vibration may be transmitted to the

structure Care must also be taken to protect

the coils and fins from damage due to

vandalism or other hazards

Airflow to and from the condensing unit

must not be restricted Coils and fans must

be free of any obstructions and debris in

order to start and operate properly with a

correct amount of airflow Obstruction to air

flow will result in decreased performance

and efficiency

The installation position must provide at

least one foot of clearance from the wall for

proper air flow to the coils When multiple

units are mounted adjacent to each other the

clearance required between them is three

feet

Service compartment must be accessible for

periodic servicing of controls safety

devices and refrigerant serviceshutoff

valves At least two feet of clearance on this

Incorrect lifting can cause damage to the unit

CAUTION

15

corner of the unit is recommended for

service

Figure 2 ndash Condensing Unit Clearances

Condensing units should not be installed in

an enclosure or pit that is deeper than the

height of the unit When recessed

installation is necessary the clearance to

maintain proper airflow is at least three feet

CB Series condensing units are single

circuited with vertical air discharge There

must be no obstruction above the equipment

Do not place the unit under an overhang

Placement relative to the building air intakes

and other structures must be carefully

selected Consider the effects of outdoor fan

noise on conditioned space and any adjacent

occupied space It is recommended that the

unit be placed so that discharge does not

blow toward windows less than 25 feet

away

Heat pumps require special location

consideration in areas where snow

accumulation can become an obstruction

and in areas with prolonged continuous

subfreezing temperatures Heat pump unit

bases are cutout under the outdoor coil to

permit drainage of frost accumulation The

unit must be situated to permit free

unobstructed drainage of the defrost water

and ice A minimum 3 inches clearance

under the outdoor coil is required in the

milder climates In more severe weather

locations it is recommended that the unit be

elevated to allow unobstructed drainage and

airflow

Table 1 - Recommended Elevation

Minimums

Design

Temperature

Suggest Minimum

Elevation

+15 F and above 3rdquo

-5 F to +17 F 8rdquo

Below -5 F 12rdquo

Mounting Isolation

For roof mounted applications or anytime

vibration transmission is a factor vibration

isolators may be used

Access Panel

Access panel is provided to electrical

compartment To remove the panel

unscrew the four screws

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

16

Electrical

Verify the unit nameplate agrees with the

power supply Connect power and control

field wiring as shown on the unit wiring

diagram provided with the unit

Route power and control wiring separately

through the utility entry right above the

service valves Do not run power and signal

wires in the same conduit

Figure 3 ndash Utility Entry

Size supply conductors based on the unit

MCA rating Supply conductors must be

rated a minimum of 75degC

Protect the branch circuit in accordance with

code requirements The unit must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Note Units are factory wired for 208V

230V 460V or 575V In some units the

208V and 230V options may also be

provided in single or three phase

configurations The transformer

configuration must be checked by a

qualified technician prior to startup

Wire power leads to the unit terminal block

All wiring beyond this point has been done

by the manufacturer and cannot be modified

without affecting the units agencysafety

certification

All units require field supplied electrical

overcurrent and short circuit protection

Device must not be sized larger than the

Maximum Overcurrent Protection (MOP)

shown on the unit nameplate

Codes may require a disconnect switch be

within sight of the unit

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Before attempting to perform any installation service or maintenance shut off all electrical power to the unit at the disconnect switches Unit may have multiple power supplies Failure to disconnect power could result in dangerous operation serious injury death or property damage

WARNING

17

It is recommended that the field installed

overcurrent protection or disconnect switch

not be installed on the unit

Supply voltage must be within the minmax

range shown on the unit nameplate

Available short circuit current should not

exceed the short circuit current rating

(SCCR) shown on the unit nameplate

Three phase voltage imbalance will cause

motor overheating and premature failure

The maximum allowable imbalance is 20

Voltage imbalance is defined as 100 times

the maximum deviation from the average

voltage divided by the average voltage

Example

(221V+230V+227V)3 = 226V then

100(226V-221V)226V = 22 which

exceeds the allowable imbalance

Check voltage imbalance at the unit

disconnect switch and at the compressor

terminal Contact your local power company

for line voltage corrections

Installing contractor must check for proper

motor rotation and check blower motor

amperage listed on the motor nameplate is

not exceeded

Wire control signals to the unitrsquos low

voltage terminal block located in the

controls compartment

If any factory installed wiring must be

replaced use a minimum 105degC type AWM

insulated conductors

Thermostat

If a thermostat is used for unit control

thermostat should be located on an inside

wall 4-5 feet above the floor where it will

not be subjected to drafts sun exposure or

heat from electrical fixtures or appliances

Follow thermostat manufacturerrsquos

instructions for general installation

procedure

Thermostat control wiring size must be large

enough to prevent excess voltage drop and

ensure proper operation

All external devices must be powered via a

separate external power supply

Units with the modulating hot gas reheat

dehumidification feature must use a

humidistat or a thermostat with a normally

closed (NC) dehumidification option The

following thermostats have been approved

for usage with the dehumidification feature

Robertshawreg 9825i2 Thermostat

Honeywell VisionPROreg IAQ Thermostat

AAON Mini Controller

Three phase voltage imbalance will cause motor overheating and premature failure

CAUTION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 7: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

7

FIRE EXPLOSION OR CARBON MONOXIDE POISONING HAZARD Failure to replace proper controls could result in fire explosion or carbon monoxide poisoning Failure to follow safety warnings exactly could result in serious injury death or property damage Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this appliance

WARNING

LIVE ELECTRICAL During installation testing servicing and troubleshooting of the equipment it may be necessary to work with live electrical components Only a qualified licensed electrician or individual properly trained in handling live electrical components shall perform these tasks Standard NFPA-70E an OSHA regulation requiring an Arc Flash Boundary to be field established and marked for identification of where appropriate Personal Protective Equipment (PPE) be worn should be followed

WARNING

GROUNDING REQUIRED All field installed wiring must be completed by qualified personnel Field installed wiring must comply with NECCEC local and state electrical code requirements Failure to follow code requirements could result in serious injury or death Provide proper unit ground in accordance with these code requirements

WARNING

ROTATING COMPONENTS Unit contains fans with moving parts that can cause serious injury Do not remove grill containing fans until the power to the unit has been disconnected and fan has stopped rotating

WARNING

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of 3 phase units at startup by a qualified service technician Scroll compressors are directional and can be damaged if rotated in the wrong direction Compressor rotation must be checked using suction and discharge gauges Fan motor rotation should be checked for proper operation Alterations should only be made at the unit power connection

CAUTION

8

Compartments containing hazardous voltage or rotating parts are equipped with a panel requiring tooled access Always re-install screws on the panel after installation or service is completed

CAUTION

UNIT HANDLING To prevent injury or death lifting equipment capacity shall exceed unit weight by an adequate safety factor Always test-lift unit not more than 24 inches high to verify proper center of gravity lift point to avoid unit damage injury or death

WARNING

LEAK TESTING

Do not use oxygen acetylene or air in place of refrigerant and dry nitrogen for leak testing A violent explosion may result causing injury or death

WARNING

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

COIL CLEANERS

To prevent damage to the unit do not use acidic chemical coil cleaners Do not use alkaline chemical coil cleaners with a pH value greater than 85 after mixing without first using an aluminum corrosion inhibitor in the cleaning solution

CAUTION

COIL CLEANERS

Some chemical coil cleaning compounds are caustic or toxic Use these substances only in accordance with the manufacturerrsquos usage instructions Failure to follow instructions may result in equipment damage injury or death

WARNING

9

1 Startup and service must be performed

by a Factory Trained Service

Technician

2 The unit is for outdoor use only See

General Information section for more

unit information

3 Every unit has a unique equipment

nameplate with electrical operational

and unit clearance specifications

Always refer to the unit nameplate for

specific ratings unique to the model you

have purchased

4 READ THE ENTIRE INSTALLATION

OPERATION AND MAINTENANCE

MANUAL OTHER IMPORTANT

SAFETY PRECAUTIONS ARE

PROVIDED THROUGHOUT THIS

MANUAL

5 Keep this manual and all literature

safeguarded near or on the unit

COIL CLEANING

Do not clean DX refrigerant coils with hot water or steam The use of hot water or steam on refrigerant coils will cause high pressure inside the coil tubing and damage to the coil

CAUTION

ENCLOSED AREA

Do not work in an enclosed area where refrigerant or nitrogen gases may be leaking A sufficient quantity of vapors may be present and cause

injury or death

WARNING

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

CB Series Feature String Nomenclature

Model Options Unit Feature Options

GE

N

MJ

RE

V

UN

IT

SIZ

E

VL

T

CO

MP

CK

TS

1

2

3

4

5

6

7

CB - B - 060 - 3 - B - 1 B D 0 0 D A 0

10

CB Base Model and Features Description

BASE MODEL SERIES AND GENERATION

CB

REVISION

B = Design Sequence

UNIT SIZE

024 = 24 MBH - 2 Ton - Vertical Discharge

036 = 36 MBH - 3 Ton - Vertical Discharge

048 = 48 MBH - 4 Ton - Vertical Discharge

060 = 60 MBH - 5 Ton - Vertical Discharge

VOLTAGE

1 = 230V1Φ60Hz

2 = 230V3Φ60Hz

3 = 460V3Φ60Hz

4 = 575V3Φ60Hz

8 = 208V3Φ60Hz

9 = 208V1Φ60Hz

COMPRESSOR TYPE

B = R-410A Two Step Scroll Compressor

D = R-410A Variable Capacity Scroll Compressor

F = R-410A Two Step Scroll Compressor with Sound

Blanket

H = R-410A Variable Capacity Scroll Compressor

with Sound Blanket

NUMBER OF CIRCUITS

1 = One Circuit

FEATURE 1 AMBIENT CONTROL 0 = Standard (55degF Ambient)

B = Adjustable Fan Cycling (35degF Ambient)

D = Modulating Fan Pressure Control (35degF

Ambient)

F = Flooded Condenser Ambient Controls (0degF) +

Option B

G = Flooded Condenser Ambient Controls (0degF) +

Option D

FEATURE 2 REFRIGERATION

OPTIONS 0 = Standard - Split System Air Conditioner

A = External Hot Gas Bypass

B = Split System Heat Pump

D = Modulating Hot Gas Reheat

F = Options A + D

G = Options B + D

FEATURE 3 CONTROLS

0 = Standard - Terminal Block

A = Suction Pressure Transducer (F1- Wattmaster

Reheat)

H = Control Circuit Transformer

S = Suction Pressure Transducer (Not F1 -

Wattmaster Controls)

T = Control Circuit Transformer w Suction Pressure

Transducer

FEATURE 4 COIL PROTECTION

0 = Standard

A = Polymer E-Coated Coil

FEATURE 5 CABINET OPTIONS D = Standard ndash Louvered Panels + 2500 Hour Salt-

Spray Tested Exterior Paint

G = Wire Grille + 2500 Hour Salt-Spray Tested

Exterior Paint

FEATURE 6 WARRANTY 0 = Standard

A = Second to Fifth Year Extended Compressor

Warranty

FEATURE 7 TYPE 0 = Standard

X = Special Pricing Authorization

11

General Description

AAON CB Series condensing units have

been designed for outdoor installation only

Startup and service must be performed by a

Factory Trained Service Technician

Codes and Ordinances

CB Series units have been tested and

certified by ETL in accordance with UL

Safety Standard 1995CSA C222 No 236

System should be sized in accordance with

the American Society of Heating

Refrigeration and Air Conditioning

Engineers Handbook

Installation of CB Series units must conform

to the ICC standards of the International

Mechanical Code the International Building

Code and local building plumbing and

waste water codes All appliances must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Receiving Unit

When received the unit should be checked

for damage that might have occurred in

transit If damage is found it should be noted

on the carrierrsquos Freight Bill A request for

inspection by carrierrsquos agent should be made

in writing at once

Nameplate should be checked to ensure the

correct model sizes and voltages have been

received to match the job requirements

If repairs must be made to damaged goods

then the factory should be notified before

any repair action is taken in order to protect

the warranty Certain equipment alteration

repair and manipulation of equipment

without the manufacturerrsquos consent may

void the product warranty Contact AAON

Warranty Department for assistance with

handling damaged goods repairs and

freight claims (903) 236-4403

NOTE Upon receipt check shipment for

items that ship loose Consult order and

shipment documentation to identify potential

loose-shipped items Loose-shipped items

The Clean Air Act of 1990 bans the intentional venting of refrigerant as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed

CAUTION

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a Factory Trained Service Technician

WARNING

SHARP EDGES

Coils and sheet metal surfaces present sharp edges and care must be taken when working with equipment

WARNING

Failure to observe the following instructions will result in premature failure of your system and possible voiding of the warranty

WARNING

12

may have been placed inside the unit cabinet

for security Installers and owners should

secure all doors with locks or nuts and bolts

to prevent unauthorized access

The warranty card must be completed in full

and returned to AAON not more than 3

months after the unit is delivered

Storage

If installation will not occur immediately

following delivery store equipment in a dry

protected area away from construction

traffic and in the proper orientation as

marked on the packaging with all internal

packaging in place Secure all loose-shipped

items

Direct Expansion (DX) Condensing Units

CB Series condensing units are factory

assembled and wired including a full charge

of R-410A refrigerant for up to 25 feet of

line set Systems with the modulating hot

gas reheat option will require refrigerant to

be field added because of the additional

refrigerant components and piping

associated with the system

Failure to observe the following instructions

may result in premature failure of your

system and possible voiding of the

warranty

Never cut off the main power supply to the

unit except for servicing emergency or

complete shutdown of the unit When power

is cut off from the unit compressors using

crankcase heaters cannot prevent refrigerant

migration This means the compressor may

cool down and liquid refrigerant may

accumulate in the compressor Since the

compressor is designed to pump refrigerant

gas damage may occur when power is

restored

If power to the unit must be off for more

than an hour turn the thermostat system

switch to ldquoOffrdquo or turn the unit off at the

control panel and then cut off the main

power supply Leave the unit off until the

main power supply has been turned on again

for at least 24 hours This will give the

crankcase heater time to clear any liquid

accumulation out of the compressor before it

is required to run

Always control the system from the

thermostat or control panel never at the

main power supply except for servicing

emergency or complete shutdown of the

unit

The standard compressors must be on a

minimum of 5 minutes and off for a

minimum of 5 minutes The cycle rate must

be no more than 6 starts per hour

The variable capacity compressors must be

on a minimum of 3 minutes and off for a

minimum of 3 minutes The cycle rate must

be no more than 10 starts per hour

The compressor life will be seriously

shortened by reduced lubrication and the

pumping of excessive amounts of liquid oil

and liquid refrigerant

CRANKCASE HEATER OPERATION

Units are equipped with compressor crankcase heaters which should be energized at least 24 hours prior to cooling operation to clear any liquid refrigerant from the compressors

CAUTION

13

Note Low Ambient Operation

Units without a low ambient option such as

condenser fan cycling or the 0degF low

ambient option will not operate in the

cooling mode of operation properly when

the outdoor temperature is below 55degF Low

ambient andor air handling unit economizer

options are recommended if cooling

operation below 55degF is expected

Note Multiple Systems with Multiple

Thermostats

When several heating and cooling split

systems are used to condition a space all

thermostat switches must be set in either

heating mode cooling mode or off Do not

leave part of the systems switched to the

opposite mode Cooling only systems should

be switched off at the thermostat during the

heating season

Wiring Diagrams

Unit specific wiring diagram is laminated in

plastic and located inside the controls

compartment door

General Maintenance

When the initial startup is made and on a

periodic schedule during operation it is

necessary to perform routine service checks

on the performance of the condensing unit

This includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

14

Installation

AAON equipment has been designed for

quick and easy installation

Lifting the Unit

CB Series condensing units have channels

underneath the base which provide lifting

access to the underside of the equipment and

allow moving and placement without

physical damage

Figure 1 ndash Forklift Channels amp Access Panel

Dollies andor carts are recommended to lift

and place the unit to prevent damage to the

equipment and injury to the installer

Care should be taken if using spreader bars

blocking or other lifting devices to prevent

any damage to the cabinet coil or

condensing fans

Before lifting unit be sure that all shipping

material has been removed from unit

Hoist unit to a point directly above the

condenser pad and lower unit into the

proper place Unit may also be positioned

with a dolly When the unit is in place

remove the dolly or lifting device Make

sure the unit is properly seated and level

Locating Unit

CB Series condensing units are designed for

outdoor application and placement at ground

level or on a rooftop Units must be placed

on a level and solid foundation that can

support the unitrsquos weight

When rooftop mounted a steel frame must

be provided that will support the unit above

the roof itself for load distribution

When installed at ground level a one-piece

concrete slab or composite condenser pad

should be used with footings that extend

below the frost line (a substantial base that

will not settle) Slab should be surrounded

by a graveled area for proper drainage and

should not adjoin the building as sound and

vibration may be transmitted to the

structure Care must also be taken to protect

the coils and fins from damage due to

vandalism or other hazards

Airflow to and from the condensing unit

must not be restricted Coils and fans must

be free of any obstructions and debris in

order to start and operate properly with a

correct amount of airflow Obstruction to air

flow will result in decreased performance

and efficiency

The installation position must provide at

least one foot of clearance from the wall for

proper air flow to the coils When multiple

units are mounted adjacent to each other the

clearance required between them is three

feet

Service compartment must be accessible for

periodic servicing of controls safety

devices and refrigerant serviceshutoff

valves At least two feet of clearance on this

Incorrect lifting can cause damage to the unit

CAUTION

15

corner of the unit is recommended for

service

Figure 2 ndash Condensing Unit Clearances

Condensing units should not be installed in

an enclosure or pit that is deeper than the

height of the unit When recessed

installation is necessary the clearance to

maintain proper airflow is at least three feet

CB Series condensing units are single

circuited with vertical air discharge There

must be no obstruction above the equipment

Do not place the unit under an overhang

Placement relative to the building air intakes

and other structures must be carefully

selected Consider the effects of outdoor fan

noise on conditioned space and any adjacent

occupied space It is recommended that the

unit be placed so that discharge does not

blow toward windows less than 25 feet

away

Heat pumps require special location

consideration in areas where snow

accumulation can become an obstruction

and in areas with prolonged continuous

subfreezing temperatures Heat pump unit

bases are cutout under the outdoor coil to

permit drainage of frost accumulation The

unit must be situated to permit free

unobstructed drainage of the defrost water

and ice A minimum 3 inches clearance

under the outdoor coil is required in the

milder climates In more severe weather

locations it is recommended that the unit be

elevated to allow unobstructed drainage and

airflow

Table 1 - Recommended Elevation

Minimums

Design

Temperature

Suggest Minimum

Elevation

+15 F and above 3rdquo

-5 F to +17 F 8rdquo

Below -5 F 12rdquo

Mounting Isolation

For roof mounted applications or anytime

vibration transmission is a factor vibration

isolators may be used

Access Panel

Access panel is provided to electrical

compartment To remove the panel

unscrew the four screws

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

16

Electrical

Verify the unit nameplate agrees with the

power supply Connect power and control

field wiring as shown on the unit wiring

diagram provided with the unit

Route power and control wiring separately

through the utility entry right above the

service valves Do not run power and signal

wires in the same conduit

Figure 3 ndash Utility Entry

Size supply conductors based on the unit

MCA rating Supply conductors must be

rated a minimum of 75degC

Protect the branch circuit in accordance with

code requirements The unit must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Note Units are factory wired for 208V

230V 460V or 575V In some units the

208V and 230V options may also be

provided in single or three phase

configurations The transformer

configuration must be checked by a

qualified technician prior to startup

Wire power leads to the unit terminal block

All wiring beyond this point has been done

by the manufacturer and cannot be modified

without affecting the units agencysafety

certification

All units require field supplied electrical

overcurrent and short circuit protection

Device must not be sized larger than the

Maximum Overcurrent Protection (MOP)

shown on the unit nameplate

Codes may require a disconnect switch be

within sight of the unit

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Before attempting to perform any installation service or maintenance shut off all electrical power to the unit at the disconnect switches Unit may have multiple power supplies Failure to disconnect power could result in dangerous operation serious injury death or property damage

WARNING

17

It is recommended that the field installed

overcurrent protection or disconnect switch

not be installed on the unit

Supply voltage must be within the minmax

range shown on the unit nameplate

Available short circuit current should not

exceed the short circuit current rating

(SCCR) shown on the unit nameplate

Three phase voltage imbalance will cause

motor overheating and premature failure

The maximum allowable imbalance is 20

Voltage imbalance is defined as 100 times

the maximum deviation from the average

voltage divided by the average voltage

Example

(221V+230V+227V)3 = 226V then

100(226V-221V)226V = 22 which

exceeds the allowable imbalance

Check voltage imbalance at the unit

disconnect switch and at the compressor

terminal Contact your local power company

for line voltage corrections

Installing contractor must check for proper

motor rotation and check blower motor

amperage listed on the motor nameplate is

not exceeded

Wire control signals to the unitrsquos low

voltage terminal block located in the

controls compartment

If any factory installed wiring must be

replaced use a minimum 105degC type AWM

insulated conductors

Thermostat

If a thermostat is used for unit control

thermostat should be located on an inside

wall 4-5 feet above the floor where it will

not be subjected to drafts sun exposure or

heat from electrical fixtures or appliances

Follow thermostat manufacturerrsquos

instructions for general installation

procedure

Thermostat control wiring size must be large

enough to prevent excess voltage drop and

ensure proper operation

All external devices must be powered via a

separate external power supply

Units with the modulating hot gas reheat

dehumidification feature must use a

humidistat or a thermostat with a normally

closed (NC) dehumidification option The

following thermostats have been approved

for usage with the dehumidification feature

Robertshawreg 9825i2 Thermostat

Honeywell VisionPROreg IAQ Thermostat

AAON Mini Controller

Three phase voltage imbalance will cause motor overheating and premature failure

CAUTION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 8: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

8

Compartments containing hazardous voltage or rotating parts are equipped with a panel requiring tooled access Always re-install screws on the panel after installation or service is completed

CAUTION

UNIT HANDLING To prevent injury or death lifting equipment capacity shall exceed unit weight by an adequate safety factor Always test-lift unit not more than 24 inches high to verify proper center of gravity lift point to avoid unit damage injury or death

WARNING

LEAK TESTING

Do not use oxygen acetylene or air in place of refrigerant and dry nitrogen for leak testing A violent explosion may result causing injury or death

WARNING

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

COIL CLEANERS

To prevent damage to the unit do not use acidic chemical coil cleaners Do not use alkaline chemical coil cleaners with a pH value greater than 85 after mixing without first using an aluminum corrosion inhibitor in the cleaning solution

CAUTION

COIL CLEANERS

Some chemical coil cleaning compounds are caustic or toxic Use these substances only in accordance with the manufacturerrsquos usage instructions Failure to follow instructions may result in equipment damage injury or death

WARNING

9

1 Startup and service must be performed

by a Factory Trained Service

Technician

2 The unit is for outdoor use only See

General Information section for more

unit information

3 Every unit has a unique equipment

nameplate with electrical operational

and unit clearance specifications

Always refer to the unit nameplate for

specific ratings unique to the model you

have purchased

4 READ THE ENTIRE INSTALLATION

OPERATION AND MAINTENANCE

MANUAL OTHER IMPORTANT

SAFETY PRECAUTIONS ARE

PROVIDED THROUGHOUT THIS

MANUAL

5 Keep this manual and all literature

safeguarded near or on the unit

COIL CLEANING

Do not clean DX refrigerant coils with hot water or steam The use of hot water or steam on refrigerant coils will cause high pressure inside the coil tubing and damage to the coil

CAUTION

ENCLOSED AREA

Do not work in an enclosed area where refrigerant or nitrogen gases may be leaking A sufficient quantity of vapors may be present and cause

injury or death

WARNING

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

CB Series Feature String Nomenclature

Model Options Unit Feature Options

GE

N

MJ

RE

V

UN

IT

SIZ

E

VL

T

CO

MP

CK

TS

1

2

3

4

5

6

7

CB - B - 060 - 3 - B - 1 B D 0 0 D A 0

10

CB Base Model and Features Description

BASE MODEL SERIES AND GENERATION

CB

REVISION

B = Design Sequence

UNIT SIZE

024 = 24 MBH - 2 Ton - Vertical Discharge

036 = 36 MBH - 3 Ton - Vertical Discharge

048 = 48 MBH - 4 Ton - Vertical Discharge

060 = 60 MBH - 5 Ton - Vertical Discharge

VOLTAGE

1 = 230V1Φ60Hz

2 = 230V3Φ60Hz

3 = 460V3Φ60Hz

4 = 575V3Φ60Hz

8 = 208V3Φ60Hz

9 = 208V1Φ60Hz

COMPRESSOR TYPE

B = R-410A Two Step Scroll Compressor

D = R-410A Variable Capacity Scroll Compressor

F = R-410A Two Step Scroll Compressor with Sound

Blanket

H = R-410A Variable Capacity Scroll Compressor

with Sound Blanket

NUMBER OF CIRCUITS

1 = One Circuit

FEATURE 1 AMBIENT CONTROL 0 = Standard (55degF Ambient)

B = Adjustable Fan Cycling (35degF Ambient)

D = Modulating Fan Pressure Control (35degF

Ambient)

F = Flooded Condenser Ambient Controls (0degF) +

Option B

G = Flooded Condenser Ambient Controls (0degF) +

Option D

FEATURE 2 REFRIGERATION

OPTIONS 0 = Standard - Split System Air Conditioner

A = External Hot Gas Bypass

B = Split System Heat Pump

D = Modulating Hot Gas Reheat

F = Options A + D

G = Options B + D

FEATURE 3 CONTROLS

0 = Standard - Terminal Block

A = Suction Pressure Transducer (F1- Wattmaster

Reheat)

H = Control Circuit Transformer

S = Suction Pressure Transducer (Not F1 -

Wattmaster Controls)

T = Control Circuit Transformer w Suction Pressure

Transducer

FEATURE 4 COIL PROTECTION

0 = Standard

A = Polymer E-Coated Coil

FEATURE 5 CABINET OPTIONS D = Standard ndash Louvered Panels + 2500 Hour Salt-

Spray Tested Exterior Paint

G = Wire Grille + 2500 Hour Salt-Spray Tested

Exterior Paint

FEATURE 6 WARRANTY 0 = Standard

A = Second to Fifth Year Extended Compressor

Warranty

FEATURE 7 TYPE 0 = Standard

X = Special Pricing Authorization

11

General Description

AAON CB Series condensing units have

been designed for outdoor installation only

Startup and service must be performed by a

Factory Trained Service Technician

Codes and Ordinances

CB Series units have been tested and

certified by ETL in accordance with UL

Safety Standard 1995CSA C222 No 236

System should be sized in accordance with

the American Society of Heating

Refrigeration and Air Conditioning

Engineers Handbook

Installation of CB Series units must conform

to the ICC standards of the International

Mechanical Code the International Building

Code and local building plumbing and

waste water codes All appliances must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Receiving Unit

When received the unit should be checked

for damage that might have occurred in

transit If damage is found it should be noted

on the carrierrsquos Freight Bill A request for

inspection by carrierrsquos agent should be made

in writing at once

Nameplate should be checked to ensure the

correct model sizes and voltages have been

received to match the job requirements

If repairs must be made to damaged goods

then the factory should be notified before

any repair action is taken in order to protect

the warranty Certain equipment alteration

repair and manipulation of equipment

without the manufacturerrsquos consent may

void the product warranty Contact AAON

Warranty Department for assistance with

handling damaged goods repairs and

freight claims (903) 236-4403

NOTE Upon receipt check shipment for

items that ship loose Consult order and

shipment documentation to identify potential

loose-shipped items Loose-shipped items

The Clean Air Act of 1990 bans the intentional venting of refrigerant as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed

CAUTION

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a Factory Trained Service Technician

WARNING

SHARP EDGES

Coils and sheet metal surfaces present sharp edges and care must be taken when working with equipment

WARNING

Failure to observe the following instructions will result in premature failure of your system and possible voiding of the warranty

WARNING

12

may have been placed inside the unit cabinet

for security Installers and owners should

secure all doors with locks or nuts and bolts

to prevent unauthorized access

The warranty card must be completed in full

and returned to AAON not more than 3

months after the unit is delivered

Storage

If installation will not occur immediately

following delivery store equipment in a dry

protected area away from construction

traffic and in the proper orientation as

marked on the packaging with all internal

packaging in place Secure all loose-shipped

items

Direct Expansion (DX) Condensing Units

CB Series condensing units are factory

assembled and wired including a full charge

of R-410A refrigerant for up to 25 feet of

line set Systems with the modulating hot

gas reheat option will require refrigerant to

be field added because of the additional

refrigerant components and piping

associated with the system

Failure to observe the following instructions

may result in premature failure of your

system and possible voiding of the

warranty

Never cut off the main power supply to the

unit except for servicing emergency or

complete shutdown of the unit When power

is cut off from the unit compressors using

crankcase heaters cannot prevent refrigerant

migration This means the compressor may

cool down and liquid refrigerant may

accumulate in the compressor Since the

compressor is designed to pump refrigerant

gas damage may occur when power is

restored

If power to the unit must be off for more

than an hour turn the thermostat system

switch to ldquoOffrdquo or turn the unit off at the

control panel and then cut off the main

power supply Leave the unit off until the

main power supply has been turned on again

for at least 24 hours This will give the

crankcase heater time to clear any liquid

accumulation out of the compressor before it

is required to run

Always control the system from the

thermostat or control panel never at the

main power supply except for servicing

emergency or complete shutdown of the

unit

The standard compressors must be on a

minimum of 5 minutes and off for a

minimum of 5 minutes The cycle rate must

be no more than 6 starts per hour

The variable capacity compressors must be

on a minimum of 3 minutes and off for a

minimum of 3 minutes The cycle rate must

be no more than 10 starts per hour

The compressor life will be seriously

shortened by reduced lubrication and the

pumping of excessive amounts of liquid oil

and liquid refrigerant

CRANKCASE HEATER OPERATION

Units are equipped with compressor crankcase heaters which should be energized at least 24 hours prior to cooling operation to clear any liquid refrigerant from the compressors

CAUTION

13

Note Low Ambient Operation

Units without a low ambient option such as

condenser fan cycling or the 0degF low

ambient option will not operate in the

cooling mode of operation properly when

the outdoor temperature is below 55degF Low

ambient andor air handling unit economizer

options are recommended if cooling

operation below 55degF is expected

Note Multiple Systems with Multiple

Thermostats

When several heating and cooling split

systems are used to condition a space all

thermostat switches must be set in either

heating mode cooling mode or off Do not

leave part of the systems switched to the

opposite mode Cooling only systems should

be switched off at the thermostat during the

heating season

Wiring Diagrams

Unit specific wiring diagram is laminated in

plastic and located inside the controls

compartment door

General Maintenance

When the initial startup is made and on a

periodic schedule during operation it is

necessary to perform routine service checks

on the performance of the condensing unit

This includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

14

Installation

AAON equipment has been designed for

quick and easy installation

Lifting the Unit

CB Series condensing units have channels

underneath the base which provide lifting

access to the underside of the equipment and

allow moving and placement without

physical damage

Figure 1 ndash Forklift Channels amp Access Panel

Dollies andor carts are recommended to lift

and place the unit to prevent damage to the

equipment and injury to the installer

Care should be taken if using spreader bars

blocking or other lifting devices to prevent

any damage to the cabinet coil or

condensing fans

Before lifting unit be sure that all shipping

material has been removed from unit

Hoist unit to a point directly above the

condenser pad and lower unit into the

proper place Unit may also be positioned

with a dolly When the unit is in place

remove the dolly or lifting device Make

sure the unit is properly seated and level

Locating Unit

CB Series condensing units are designed for

outdoor application and placement at ground

level or on a rooftop Units must be placed

on a level and solid foundation that can

support the unitrsquos weight

When rooftop mounted a steel frame must

be provided that will support the unit above

the roof itself for load distribution

When installed at ground level a one-piece

concrete slab or composite condenser pad

should be used with footings that extend

below the frost line (a substantial base that

will not settle) Slab should be surrounded

by a graveled area for proper drainage and

should not adjoin the building as sound and

vibration may be transmitted to the

structure Care must also be taken to protect

the coils and fins from damage due to

vandalism or other hazards

Airflow to and from the condensing unit

must not be restricted Coils and fans must

be free of any obstructions and debris in

order to start and operate properly with a

correct amount of airflow Obstruction to air

flow will result in decreased performance

and efficiency

The installation position must provide at

least one foot of clearance from the wall for

proper air flow to the coils When multiple

units are mounted adjacent to each other the

clearance required between them is three

feet

Service compartment must be accessible for

periodic servicing of controls safety

devices and refrigerant serviceshutoff

valves At least two feet of clearance on this

Incorrect lifting can cause damage to the unit

CAUTION

15

corner of the unit is recommended for

service

Figure 2 ndash Condensing Unit Clearances

Condensing units should not be installed in

an enclosure or pit that is deeper than the

height of the unit When recessed

installation is necessary the clearance to

maintain proper airflow is at least three feet

CB Series condensing units are single

circuited with vertical air discharge There

must be no obstruction above the equipment

Do not place the unit under an overhang

Placement relative to the building air intakes

and other structures must be carefully

selected Consider the effects of outdoor fan

noise on conditioned space and any adjacent

occupied space It is recommended that the

unit be placed so that discharge does not

blow toward windows less than 25 feet

away

Heat pumps require special location

consideration in areas where snow

accumulation can become an obstruction

and in areas with prolonged continuous

subfreezing temperatures Heat pump unit

bases are cutout under the outdoor coil to

permit drainage of frost accumulation The

unit must be situated to permit free

unobstructed drainage of the defrost water

and ice A minimum 3 inches clearance

under the outdoor coil is required in the

milder climates In more severe weather

locations it is recommended that the unit be

elevated to allow unobstructed drainage and

airflow

Table 1 - Recommended Elevation

Minimums

Design

Temperature

Suggest Minimum

Elevation

+15 F and above 3rdquo

-5 F to +17 F 8rdquo

Below -5 F 12rdquo

Mounting Isolation

For roof mounted applications or anytime

vibration transmission is a factor vibration

isolators may be used

Access Panel

Access panel is provided to electrical

compartment To remove the panel

unscrew the four screws

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

16

Electrical

Verify the unit nameplate agrees with the

power supply Connect power and control

field wiring as shown on the unit wiring

diagram provided with the unit

Route power and control wiring separately

through the utility entry right above the

service valves Do not run power and signal

wires in the same conduit

Figure 3 ndash Utility Entry

Size supply conductors based on the unit

MCA rating Supply conductors must be

rated a minimum of 75degC

Protect the branch circuit in accordance with

code requirements The unit must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Note Units are factory wired for 208V

230V 460V or 575V In some units the

208V and 230V options may also be

provided in single or three phase

configurations The transformer

configuration must be checked by a

qualified technician prior to startup

Wire power leads to the unit terminal block

All wiring beyond this point has been done

by the manufacturer and cannot be modified

without affecting the units agencysafety

certification

All units require field supplied electrical

overcurrent and short circuit protection

Device must not be sized larger than the

Maximum Overcurrent Protection (MOP)

shown on the unit nameplate

Codes may require a disconnect switch be

within sight of the unit

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Before attempting to perform any installation service or maintenance shut off all electrical power to the unit at the disconnect switches Unit may have multiple power supplies Failure to disconnect power could result in dangerous operation serious injury death or property damage

WARNING

17

It is recommended that the field installed

overcurrent protection or disconnect switch

not be installed on the unit

Supply voltage must be within the minmax

range shown on the unit nameplate

Available short circuit current should not

exceed the short circuit current rating

(SCCR) shown on the unit nameplate

Three phase voltage imbalance will cause

motor overheating and premature failure

The maximum allowable imbalance is 20

Voltage imbalance is defined as 100 times

the maximum deviation from the average

voltage divided by the average voltage

Example

(221V+230V+227V)3 = 226V then

100(226V-221V)226V = 22 which

exceeds the allowable imbalance

Check voltage imbalance at the unit

disconnect switch and at the compressor

terminal Contact your local power company

for line voltage corrections

Installing contractor must check for proper

motor rotation and check blower motor

amperage listed on the motor nameplate is

not exceeded

Wire control signals to the unitrsquos low

voltage terminal block located in the

controls compartment

If any factory installed wiring must be

replaced use a minimum 105degC type AWM

insulated conductors

Thermostat

If a thermostat is used for unit control

thermostat should be located on an inside

wall 4-5 feet above the floor where it will

not be subjected to drafts sun exposure or

heat from electrical fixtures or appliances

Follow thermostat manufacturerrsquos

instructions for general installation

procedure

Thermostat control wiring size must be large

enough to prevent excess voltage drop and

ensure proper operation

All external devices must be powered via a

separate external power supply

Units with the modulating hot gas reheat

dehumidification feature must use a

humidistat or a thermostat with a normally

closed (NC) dehumidification option The

following thermostats have been approved

for usage with the dehumidification feature

Robertshawreg 9825i2 Thermostat

Honeywell VisionPROreg IAQ Thermostat

AAON Mini Controller

Three phase voltage imbalance will cause motor overheating and premature failure

CAUTION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 9: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

9

1 Startup and service must be performed

by a Factory Trained Service

Technician

2 The unit is for outdoor use only See

General Information section for more

unit information

3 Every unit has a unique equipment

nameplate with electrical operational

and unit clearance specifications

Always refer to the unit nameplate for

specific ratings unique to the model you

have purchased

4 READ THE ENTIRE INSTALLATION

OPERATION AND MAINTENANCE

MANUAL OTHER IMPORTANT

SAFETY PRECAUTIONS ARE

PROVIDED THROUGHOUT THIS

MANUAL

5 Keep this manual and all literature

safeguarded near or on the unit

COIL CLEANING

Do not clean DX refrigerant coils with hot water or steam The use of hot water or steam on refrigerant coils will cause high pressure inside the coil tubing and damage to the coil

CAUTION

ENCLOSED AREA

Do not work in an enclosed area where refrigerant or nitrogen gases may be leaking A sufficient quantity of vapors may be present and cause

injury or death

WARNING

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

CB Series Feature String Nomenclature

Model Options Unit Feature Options

GE

N

MJ

RE

V

UN

IT

SIZ

E

VL

T

CO

MP

CK

TS

1

2

3

4

5

6

7

CB - B - 060 - 3 - B - 1 B D 0 0 D A 0

10

CB Base Model and Features Description

BASE MODEL SERIES AND GENERATION

CB

REVISION

B = Design Sequence

UNIT SIZE

024 = 24 MBH - 2 Ton - Vertical Discharge

036 = 36 MBH - 3 Ton - Vertical Discharge

048 = 48 MBH - 4 Ton - Vertical Discharge

060 = 60 MBH - 5 Ton - Vertical Discharge

VOLTAGE

1 = 230V1Φ60Hz

2 = 230V3Φ60Hz

3 = 460V3Φ60Hz

4 = 575V3Φ60Hz

8 = 208V3Φ60Hz

9 = 208V1Φ60Hz

COMPRESSOR TYPE

B = R-410A Two Step Scroll Compressor

D = R-410A Variable Capacity Scroll Compressor

F = R-410A Two Step Scroll Compressor with Sound

Blanket

H = R-410A Variable Capacity Scroll Compressor

with Sound Blanket

NUMBER OF CIRCUITS

1 = One Circuit

FEATURE 1 AMBIENT CONTROL 0 = Standard (55degF Ambient)

B = Adjustable Fan Cycling (35degF Ambient)

D = Modulating Fan Pressure Control (35degF

Ambient)

F = Flooded Condenser Ambient Controls (0degF) +

Option B

G = Flooded Condenser Ambient Controls (0degF) +

Option D

FEATURE 2 REFRIGERATION

OPTIONS 0 = Standard - Split System Air Conditioner

A = External Hot Gas Bypass

B = Split System Heat Pump

D = Modulating Hot Gas Reheat

F = Options A + D

G = Options B + D

FEATURE 3 CONTROLS

0 = Standard - Terminal Block

A = Suction Pressure Transducer (F1- Wattmaster

Reheat)

H = Control Circuit Transformer

S = Suction Pressure Transducer (Not F1 -

Wattmaster Controls)

T = Control Circuit Transformer w Suction Pressure

Transducer

FEATURE 4 COIL PROTECTION

0 = Standard

A = Polymer E-Coated Coil

FEATURE 5 CABINET OPTIONS D = Standard ndash Louvered Panels + 2500 Hour Salt-

Spray Tested Exterior Paint

G = Wire Grille + 2500 Hour Salt-Spray Tested

Exterior Paint

FEATURE 6 WARRANTY 0 = Standard

A = Second to Fifth Year Extended Compressor

Warranty

FEATURE 7 TYPE 0 = Standard

X = Special Pricing Authorization

11

General Description

AAON CB Series condensing units have

been designed for outdoor installation only

Startup and service must be performed by a

Factory Trained Service Technician

Codes and Ordinances

CB Series units have been tested and

certified by ETL in accordance with UL

Safety Standard 1995CSA C222 No 236

System should be sized in accordance with

the American Society of Heating

Refrigeration and Air Conditioning

Engineers Handbook

Installation of CB Series units must conform

to the ICC standards of the International

Mechanical Code the International Building

Code and local building plumbing and

waste water codes All appliances must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Receiving Unit

When received the unit should be checked

for damage that might have occurred in

transit If damage is found it should be noted

on the carrierrsquos Freight Bill A request for

inspection by carrierrsquos agent should be made

in writing at once

Nameplate should be checked to ensure the

correct model sizes and voltages have been

received to match the job requirements

If repairs must be made to damaged goods

then the factory should be notified before

any repair action is taken in order to protect

the warranty Certain equipment alteration

repair and manipulation of equipment

without the manufacturerrsquos consent may

void the product warranty Contact AAON

Warranty Department for assistance with

handling damaged goods repairs and

freight claims (903) 236-4403

NOTE Upon receipt check shipment for

items that ship loose Consult order and

shipment documentation to identify potential

loose-shipped items Loose-shipped items

The Clean Air Act of 1990 bans the intentional venting of refrigerant as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed

CAUTION

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a Factory Trained Service Technician

WARNING

SHARP EDGES

Coils and sheet metal surfaces present sharp edges and care must be taken when working with equipment

WARNING

Failure to observe the following instructions will result in premature failure of your system and possible voiding of the warranty

WARNING

12

may have been placed inside the unit cabinet

for security Installers and owners should

secure all doors with locks or nuts and bolts

to prevent unauthorized access

The warranty card must be completed in full

and returned to AAON not more than 3

months after the unit is delivered

Storage

If installation will not occur immediately

following delivery store equipment in a dry

protected area away from construction

traffic and in the proper orientation as

marked on the packaging with all internal

packaging in place Secure all loose-shipped

items

Direct Expansion (DX) Condensing Units

CB Series condensing units are factory

assembled and wired including a full charge

of R-410A refrigerant for up to 25 feet of

line set Systems with the modulating hot

gas reheat option will require refrigerant to

be field added because of the additional

refrigerant components and piping

associated with the system

Failure to observe the following instructions

may result in premature failure of your

system and possible voiding of the

warranty

Never cut off the main power supply to the

unit except for servicing emergency or

complete shutdown of the unit When power

is cut off from the unit compressors using

crankcase heaters cannot prevent refrigerant

migration This means the compressor may

cool down and liquid refrigerant may

accumulate in the compressor Since the

compressor is designed to pump refrigerant

gas damage may occur when power is

restored

If power to the unit must be off for more

than an hour turn the thermostat system

switch to ldquoOffrdquo or turn the unit off at the

control panel and then cut off the main

power supply Leave the unit off until the

main power supply has been turned on again

for at least 24 hours This will give the

crankcase heater time to clear any liquid

accumulation out of the compressor before it

is required to run

Always control the system from the

thermostat or control panel never at the

main power supply except for servicing

emergency or complete shutdown of the

unit

The standard compressors must be on a

minimum of 5 minutes and off for a

minimum of 5 minutes The cycle rate must

be no more than 6 starts per hour

The variable capacity compressors must be

on a minimum of 3 minutes and off for a

minimum of 3 minutes The cycle rate must

be no more than 10 starts per hour

The compressor life will be seriously

shortened by reduced lubrication and the

pumping of excessive amounts of liquid oil

and liquid refrigerant

CRANKCASE HEATER OPERATION

Units are equipped with compressor crankcase heaters which should be energized at least 24 hours prior to cooling operation to clear any liquid refrigerant from the compressors

CAUTION

13

Note Low Ambient Operation

Units without a low ambient option such as

condenser fan cycling or the 0degF low

ambient option will not operate in the

cooling mode of operation properly when

the outdoor temperature is below 55degF Low

ambient andor air handling unit economizer

options are recommended if cooling

operation below 55degF is expected

Note Multiple Systems with Multiple

Thermostats

When several heating and cooling split

systems are used to condition a space all

thermostat switches must be set in either

heating mode cooling mode or off Do not

leave part of the systems switched to the

opposite mode Cooling only systems should

be switched off at the thermostat during the

heating season

Wiring Diagrams

Unit specific wiring diagram is laminated in

plastic and located inside the controls

compartment door

General Maintenance

When the initial startup is made and on a

periodic schedule during operation it is

necessary to perform routine service checks

on the performance of the condensing unit

This includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

14

Installation

AAON equipment has been designed for

quick and easy installation

Lifting the Unit

CB Series condensing units have channels

underneath the base which provide lifting

access to the underside of the equipment and

allow moving and placement without

physical damage

Figure 1 ndash Forklift Channels amp Access Panel

Dollies andor carts are recommended to lift

and place the unit to prevent damage to the

equipment and injury to the installer

Care should be taken if using spreader bars

blocking or other lifting devices to prevent

any damage to the cabinet coil or

condensing fans

Before lifting unit be sure that all shipping

material has been removed from unit

Hoist unit to a point directly above the

condenser pad and lower unit into the

proper place Unit may also be positioned

with a dolly When the unit is in place

remove the dolly or lifting device Make

sure the unit is properly seated and level

Locating Unit

CB Series condensing units are designed for

outdoor application and placement at ground

level or on a rooftop Units must be placed

on a level and solid foundation that can

support the unitrsquos weight

When rooftop mounted a steel frame must

be provided that will support the unit above

the roof itself for load distribution

When installed at ground level a one-piece

concrete slab or composite condenser pad

should be used with footings that extend

below the frost line (a substantial base that

will not settle) Slab should be surrounded

by a graveled area for proper drainage and

should not adjoin the building as sound and

vibration may be transmitted to the

structure Care must also be taken to protect

the coils and fins from damage due to

vandalism or other hazards

Airflow to and from the condensing unit

must not be restricted Coils and fans must

be free of any obstructions and debris in

order to start and operate properly with a

correct amount of airflow Obstruction to air

flow will result in decreased performance

and efficiency

The installation position must provide at

least one foot of clearance from the wall for

proper air flow to the coils When multiple

units are mounted adjacent to each other the

clearance required between them is three

feet

Service compartment must be accessible for

periodic servicing of controls safety

devices and refrigerant serviceshutoff

valves At least two feet of clearance on this

Incorrect lifting can cause damage to the unit

CAUTION

15

corner of the unit is recommended for

service

Figure 2 ndash Condensing Unit Clearances

Condensing units should not be installed in

an enclosure or pit that is deeper than the

height of the unit When recessed

installation is necessary the clearance to

maintain proper airflow is at least three feet

CB Series condensing units are single

circuited with vertical air discharge There

must be no obstruction above the equipment

Do not place the unit under an overhang

Placement relative to the building air intakes

and other structures must be carefully

selected Consider the effects of outdoor fan

noise on conditioned space and any adjacent

occupied space It is recommended that the

unit be placed so that discharge does not

blow toward windows less than 25 feet

away

Heat pumps require special location

consideration in areas where snow

accumulation can become an obstruction

and in areas with prolonged continuous

subfreezing temperatures Heat pump unit

bases are cutout under the outdoor coil to

permit drainage of frost accumulation The

unit must be situated to permit free

unobstructed drainage of the defrost water

and ice A minimum 3 inches clearance

under the outdoor coil is required in the

milder climates In more severe weather

locations it is recommended that the unit be

elevated to allow unobstructed drainage and

airflow

Table 1 - Recommended Elevation

Minimums

Design

Temperature

Suggest Minimum

Elevation

+15 F and above 3rdquo

-5 F to +17 F 8rdquo

Below -5 F 12rdquo

Mounting Isolation

For roof mounted applications or anytime

vibration transmission is a factor vibration

isolators may be used

Access Panel

Access panel is provided to electrical

compartment To remove the panel

unscrew the four screws

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

16

Electrical

Verify the unit nameplate agrees with the

power supply Connect power and control

field wiring as shown on the unit wiring

diagram provided with the unit

Route power and control wiring separately

through the utility entry right above the

service valves Do not run power and signal

wires in the same conduit

Figure 3 ndash Utility Entry

Size supply conductors based on the unit

MCA rating Supply conductors must be

rated a minimum of 75degC

Protect the branch circuit in accordance with

code requirements The unit must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Note Units are factory wired for 208V

230V 460V or 575V In some units the

208V and 230V options may also be

provided in single or three phase

configurations The transformer

configuration must be checked by a

qualified technician prior to startup

Wire power leads to the unit terminal block

All wiring beyond this point has been done

by the manufacturer and cannot be modified

without affecting the units agencysafety

certification

All units require field supplied electrical

overcurrent and short circuit protection

Device must not be sized larger than the

Maximum Overcurrent Protection (MOP)

shown on the unit nameplate

Codes may require a disconnect switch be

within sight of the unit

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Before attempting to perform any installation service or maintenance shut off all electrical power to the unit at the disconnect switches Unit may have multiple power supplies Failure to disconnect power could result in dangerous operation serious injury death or property damage

WARNING

17

It is recommended that the field installed

overcurrent protection or disconnect switch

not be installed on the unit

Supply voltage must be within the minmax

range shown on the unit nameplate

Available short circuit current should not

exceed the short circuit current rating

(SCCR) shown on the unit nameplate

Three phase voltage imbalance will cause

motor overheating and premature failure

The maximum allowable imbalance is 20

Voltage imbalance is defined as 100 times

the maximum deviation from the average

voltage divided by the average voltage

Example

(221V+230V+227V)3 = 226V then

100(226V-221V)226V = 22 which

exceeds the allowable imbalance

Check voltage imbalance at the unit

disconnect switch and at the compressor

terminal Contact your local power company

for line voltage corrections

Installing contractor must check for proper

motor rotation and check blower motor

amperage listed on the motor nameplate is

not exceeded

Wire control signals to the unitrsquos low

voltage terminal block located in the

controls compartment

If any factory installed wiring must be

replaced use a minimum 105degC type AWM

insulated conductors

Thermostat

If a thermostat is used for unit control

thermostat should be located on an inside

wall 4-5 feet above the floor where it will

not be subjected to drafts sun exposure or

heat from electrical fixtures or appliances

Follow thermostat manufacturerrsquos

instructions for general installation

procedure

Thermostat control wiring size must be large

enough to prevent excess voltage drop and

ensure proper operation

All external devices must be powered via a

separate external power supply

Units with the modulating hot gas reheat

dehumidification feature must use a

humidistat or a thermostat with a normally

closed (NC) dehumidification option The

following thermostats have been approved

for usage with the dehumidification feature

Robertshawreg 9825i2 Thermostat

Honeywell VisionPROreg IAQ Thermostat

AAON Mini Controller

Three phase voltage imbalance will cause motor overheating and premature failure

CAUTION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 10: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

CB Series Feature String Nomenclature

Model Options Unit Feature Options

GE

N

MJ

RE

V

UN

IT

SIZ

E

VL

T

CO

MP

CK

TS

1

2

3

4

5

6

7

CB - B - 060 - 3 - B - 1 B D 0 0 D A 0

10

CB Base Model and Features Description

BASE MODEL SERIES AND GENERATION

CB

REVISION

B = Design Sequence

UNIT SIZE

024 = 24 MBH - 2 Ton - Vertical Discharge

036 = 36 MBH - 3 Ton - Vertical Discharge

048 = 48 MBH - 4 Ton - Vertical Discharge

060 = 60 MBH - 5 Ton - Vertical Discharge

VOLTAGE

1 = 230V1Φ60Hz

2 = 230V3Φ60Hz

3 = 460V3Φ60Hz

4 = 575V3Φ60Hz

8 = 208V3Φ60Hz

9 = 208V1Φ60Hz

COMPRESSOR TYPE

B = R-410A Two Step Scroll Compressor

D = R-410A Variable Capacity Scroll Compressor

F = R-410A Two Step Scroll Compressor with Sound

Blanket

H = R-410A Variable Capacity Scroll Compressor

with Sound Blanket

NUMBER OF CIRCUITS

1 = One Circuit

FEATURE 1 AMBIENT CONTROL 0 = Standard (55degF Ambient)

B = Adjustable Fan Cycling (35degF Ambient)

D = Modulating Fan Pressure Control (35degF

Ambient)

F = Flooded Condenser Ambient Controls (0degF) +

Option B

G = Flooded Condenser Ambient Controls (0degF) +

Option D

FEATURE 2 REFRIGERATION

OPTIONS 0 = Standard - Split System Air Conditioner

A = External Hot Gas Bypass

B = Split System Heat Pump

D = Modulating Hot Gas Reheat

F = Options A + D

G = Options B + D

FEATURE 3 CONTROLS

0 = Standard - Terminal Block

A = Suction Pressure Transducer (F1- Wattmaster

Reheat)

H = Control Circuit Transformer

S = Suction Pressure Transducer (Not F1 -

Wattmaster Controls)

T = Control Circuit Transformer w Suction Pressure

Transducer

FEATURE 4 COIL PROTECTION

0 = Standard

A = Polymer E-Coated Coil

FEATURE 5 CABINET OPTIONS D = Standard ndash Louvered Panels + 2500 Hour Salt-

Spray Tested Exterior Paint

G = Wire Grille + 2500 Hour Salt-Spray Tested

Exterior Paint

FEATURE 6 WARRANTY 0 = Standard

A = Second to Fifth Year Extended Compressor

Warranty

FEATURE 7 TYPE 0 = Standard

X = Special Pricing Authorization

11

General Description

AAON CB Series condensing units have

been designed for outdoor installation only

Startup and service must be performed by a

Factory Trained Service Technician

Codes and Ordinances

CB Series units have been tested and

certified by ETL in accordance with UL

Safety Standard 1995CSA C222 No 236

System should be sized in accordance with

the American Society of Heating

Refrigeration and Air Conditioning

Engineers Handbook

Installation of CB Series units must conform

to the ICC standards of the International

Mechanical Code the International Building

Code and local building plumbing and

waste water codes All appliances must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Receiving Unit

When received the unit should be checked

for damage that might have occurred in

transit If damage is found it should be noted

on the carrierrsquos Freight Bill A request for

inspection by carrierrsquos agent should be made

in writing at once

Nameplate should be checked to ensure the

correct model sizes and voltages have been

received to match the job requirements

If repairs must be made to damaged goods

then the factory should be notified before

any repair action is taken in order to protect

the warranty Certain equipment alteration

repair and manipulation of equipment

without the manufacturerrsquos consent may

void the product warranty Contact AAON

Warranty Department for assistance with

handling damaged goods repairs and

freight claims (903) 236-4403

NOTE Upon receipt check shipment for

items that ship loose Consult order and

shipment documentation to identify potential

loose-shipped items Loose-shipped items

The Clean Air Act of 1990 bans the intentional venting of refrigerant as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed

CAUTION

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a Factory Trained Service Technician

WARNING

SHARP EDGES

Coils and sheet metal surfaces present sharp edges and care must be taken when working with equipment

WARNING

Failure to observe the following instructions will result in premature failure of your system and possible voiding of the warranty

WARNING

12

may have been placed inside the unit cabinet

for security Installers and owners should

secure all doors with locks or nuts and bolts

to prevent unauthorized access

The warranty card must be completed in full

and returned to AAON not more than 3

months after the unit is delivered

Storage

If installation will not occur immediately

following delivery store equipment in a dry

protected area away from construction

traffic and in the proper orientation as

marked on the packaging with all internal

packaging in place Secure all loose-shipped

items

Direct Expansion (DX) Condensing Units

CB Series condensing units are factory

assembled and wired including a full charge

of R-410A refrigerant for up to 25 feet of

line set Systems with the modulating hot

gas reheat option will require refrigerant to

be field added because of the additional

refrigerant components and piping

associated with the system

Failure to observe the following instructions

may result in premature failure of your

system and possible voiding of the

warranty

Never cut off the main power supply to the

unit except for servicing emergency or

complete shutdown of the unit When power

is cut off from the unit compressors using

crankcase heaters cannot prevent refrigerant

migration This means the compressor may

cool down and liquid refrigerant may

accumulate in the compressor Since the

compressor is designed to pump refrigerant

gas damage may occur when power is

restored

If power to the unit must be off for more

than an hour turn the thermostat system

switch to ldquoOffrdquo or turn the unit off at the

control panel and then cut off the main

power supply Leave the unit off until the

main power supply has been turned on again

for at least 24 hours This will give the

crankcase heater time to clear any liquid

accumulation out of the compressor before it

is required to run

Always control the system from the

thermostat or control panel never at the

main power supply except for servicing

emergency or complete shutdown of the

unit

The standard compressors must be on a

minimum of 5 minutes and off for a

minimum of 5 minutes The cycle rate must

be no more than 6 starts per hour

The variable capacity compressors must be

on a minimum of 3 minutes and off for a

minimum of 3 minutes The cycle rate must

be no more than 10 starts per hour

The compressor life will be seriously

shortened by reduced lubrication and the

pumping of excessive amounts of liquid oil

and liquid refrigerant

CRANKCASE HEATER OPERATION

Units are equipped with compressor crankcase heaters which should be energized at least 24 hours prior to cooling operation to clear any liquid refrigerant from the compressors

CAUTION

13

Note Low Ambient Operation

Units without a low ambient option such as

condenser fan cycling or the 0degF low

ambient option will not operate in the

cooling mode of operation properly when

the outdoor temperature is below 55degF Low

ambient andor air handling unit economizer

options are recommended if cooling

operation below 55degF is expected

Note Multiple Systems with Multiple

Thermostats

When several heating and cooling split

systems are used to condition a space all

thermostat switches must be set in either

heating mode cooling mode or off Do not

leave part of the systems switched to the

opposite mode Cooling only systems should

be switched off at the thermostat during the

heating season

Wiring Diagrams

Unit specific wiring diagram is laminated in

plastic and located inside the controls

compartment door

General Maintenance

When the initial startup is made and on a

periodic schedule during operation it is

necessary to perform routine service checks

on the performance of the condensing unit

This includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

14

Installation

AAON equipment has been designed for

quick and easy installation

Lifting the Unit

CB Series condensing units have channels

underneath the base which provide lifting

access to the underside of the equipment and

allow moving and placement without

physical damage

Figure 1 ndash Forklift Channels amp Access Panel

Dollies andor carts are recommended to lift

and place the unit to prevent damage to the

equipment and injury to the installer

Care should be taken if using spreader bars

blocking or other lifting devices to prevent

any damage to the cabinet coil or

condensing fans

Before lifting unit be sure that all shipping

material has been removed from unit

Hoist unit to a point directly above the

condenser pad and lower unit into the

proper place Unit may also be positioned

with a dolly When the unit is in place

remove the dolly or lifting device Make

sure the unit is properly seated and level

Locating Unit

CB Series condensing units are designed for

outdoor application and placement at ground

level or on a rooftop Units must be placed

on a level and solid foundation that can

support the unitrsquos weight

When rooftop mounted a steel frame must

be provided that will support the unit above

the roof itself for load distribution

When installed at ground level a one-piece

concrete slab or composite condenser pad

should be used with footings that extend

below the frost line (a substantial base that

will not settle) Slab should be surrounded

by a graveled area for proper drainage and

should not adjoin the building as sound and

vibration may be transmitted to the

structure Care must also be taken to protect

the coils and fins from damage due to

vandalism or other hazards

Airflow to and from the condensing unit

must not be restricted Coils and fans must

be free of any obstructions and debris in

order to start and operate properly with a

correct amount of airflow Obstruction to air

flow will result in decreased performance

and efficiency

The installation position must provide at

least one foot of clearance from the wall for

proper air flow to the coils When multiple

units are mounted adjacent to each other the

clearance required between them is three

feet

Service compartment must be accessible for

periodic servicing of controls safety

devices and refrigerant serviceshutoff

valves At least two feet of clearance on this

Incorrect lifting can cause damage to the unit

CAUTION

15

corner of the unit is recommended for

service

Figure 2 ndash Condensing Unit Clearances

Condensing units should not be installed in

an enclosure or pit that is deeper than the

height of the unit When recessed

installation is necessary the clearance to

maintain proper airflow is at least three feet

CB Series condensing units are single

circuited with vertical air discharge There

must be no obstruction above the equipment

Do not place the unit under an overhang

Placement relative to the building air intakes

and other structures must be carefully

selected Consider the effects of outdoor fan

noise on conditioned space and any adjacent

occupied space It is recommended that the

unit be placed so that discharge does not

blow toward windows less than 25 feet

away

Heat pumps require special location

consideration in areas where snow

accumulation can become an obstruction

and in areas with prolonged continuous

subfreezing temperatures Heat pump unit

bases are cutout under the outdoor coil to

permit drainage of frost accumulation The

unit must be situated to permit free

unobstructed drainage of the defrost water

and ice A minimum 3 inches clearance

under the outdoor coil is required in the

milder climates In more severe weather

locations it is recommended that the unit be

elevated to allow unobstructed drainage and

airflow

Table 1 - Recommended Elevation

Minimums

Design

Temperature

Suggest Minimum

Elevation

+15 F and above 3rdquo

-5 F to +17 F 8rdquo

Below -5 F 12rdquo

Mounting Isolation

For roof mounted applications or anytime

vibration transmission is a factor vibration

isolators may be used

Access Panel

Access panel is provided to electrical

compartment To remove the panel

unscrew the four screws

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

16

Electrical

Verify the unit nameplate agrees with the

power supply Connect power and control

field wiring as shown on the unit wiring

diagram provided with the unit

Route power and control wiring separately

through the utility entry right above the

service valves Do not run power and signal

wires in the same conduit

Figure 3 ndash Utility Entry

Size supply conductors based on the unit

MCA rating Supply conductors must be

rated a minimum of 75degC

Protect the branch circuit in accordance with

code requirements The unit must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Note Units are factory wired for 208V

230V 460V or 575V In some units the

208V and 230V options may also be

provided in single or three phase

configurations The transformer

configuration must be checked by a

qualified technician prior to startup

Wire power leads to the unit terminal block

All wiring beyond this point has been done

by the manufacturer and cannot be modified

without affecting the units agencysafety

certification

All units require field supplied electrical

overcurrent and short circuit protection

Device must not be sized larger than the

Maximum Overcurrent Protection (MOP)

shown on the unit nameplate

Codes may require a disconnect switch be

within sight of the unit

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Before attempting to perform any installation service or maintenance shut off all electrical power to the unit at the disconnect switches Unit may have multiple power supplies Failure to disconnect power could result in dangerous operation serious injury death or property damage

WARNING

17

It is recommended that the field installed

overcurrent protection or disconnect switch

not be installed on the unit

Supply voltage must be within the minmax

range shown on the unit nameplate

Available short circuit current should not

exceed the short circuit current rating

(SCCR) shown on the unit nameplate

Three phase voltage imbalance will cause

motor overheating and premature failure

The maximum allowable imbalance is 20

Voltage imbalance is defined as 100 times

the maximum deviation from the average

voltage divided by the average voltage

Example

(221V+230V+227V)3 = 226V then

100(226V-221V)226V = 22 which

exceeds the allowable imbalance

Check voltage imbalance at the unit

disconnect switch and at the compressor

terminal Contact your local power company

for line voltage corrections

Installing contractor must check for proper

motor rotation and check blower motor

amperage listed on the motor nameplate is

not exceeded

Wire control signals to the unitrsquos low

voltage terminal block located in the

controls compartment

If any factory installed wiring must be

replaced use a minimum 105degC type AWM

insulated conductors

Thermostat

If a thermostat is used for unit control

thermostat should be located on an inside

wall 4-5 feet above the floor where it will

not be subjected to drafts sun exposure or

heat from electrical fixtures or appliances

Follow thermostat manufacturerrsquos

instructions for general installation

procedure

Thermostat control wiring size must be large

enough to prevent excess voltage drop and

ensure proper operation

All external devices must be powered via a

separate external power supply

Units with the modulating hot gas reheat

dehumidification feature must use a

humidistat or a thermostat with a normally

closed (NC) dehumidification option The

following thermostats have been approved

for usage with the dehumidification feature

Robertshawreg 9825i2 Thermostat

Honeywell VisionPROreg IAQ Thermostat

AAON Mini Controller

Three phase voltage imbalance will cause motor overheating and premature failure

CAUTION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 11: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

11

General Description

AAON CB Series condensing units have

been designed for outdoor installation only

Startup and service must be performed by a

Factory Trained Service Technician

Codes and Ordinances

CB Series units have been tested and

certified by ETL in accordance with UL

Safety Standard 1995CSA C222 No 236

System should be sized in accordance with

the American Society of Heating

Refrigeration and Air Conditioning

Engineers Handbook

Installation of CB Series units must conform

to the ICC standards of the International

Mechanical Code the International Building

Code and local building plumbing and

waste water codes All appliances must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Receiving Unit

When received the unit should be checked

for damage that might have occurred in

transit If damage is found it should be noted

on the carrierrsquos Freight Bill A request for

inspection by carrierrsquos agent should be made

in writing at once

Nameplate should be checked to ensure the

correct model sizes and voltages have been

received to match the job requirements

If repairs must be made to damaged goods

then the factory should be notified before

any repair action is taken in order to protect

the warranty Certain equipment alteration

repair and manipulation of equipment

without the manufacturerrsquos consent may

void the product warranty Contact AAON

Warranty Department for assistance with

handling damaged goods repairs and

freight claims (903) 236-4403

NOTE Upon receipt check shipment for

items that ship loose Consult order and

shipment documentation to identify potential

loose-shipped items Loose-shipped items

The Clean Air Act of 1990 bans the intentional venting of refrigerant as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed

CAUTION

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a Factory Trained Service Technician

WARNING

SHARP EDGES

Coils and sheet metal surfaces present sharp edges and care must be taken when working with equipment

WARNING

Failure to observe the following instructions will result in premature failure of your system and possible voiding of the warranty

WARNING

12

may have been placed inside the unit cabinet

for security Installers and owners should

secure all doors with locks or nuts and bolts

to prevent unauthorized access

The warranty card must be completed in full

and returned to AAON not more than 3

months after the unit is delivered

Storage

If installation will not occur immediately

following delivery store equipment in a dry

protected area away from construction

traffic and in the proper orientation as

marked on the packaging with all internal

packaging in place Secure all loose-shipped

items

Direct Expansion (DX) Condensing Units

CB Series condensing units are factory

assembled and wired including a full charge

of R-410A refrigerant for up to 25 feet of

line set Systems with the modulating hot

gas reheat option will require refrigerant to

be field added because of the additional

refrigerant components and piping

associated with the system

Failure to observe the following instructions

may result in premature failure of your

system and possible voiding of the

warranty

Never cut off the main power supply to the

unit except for servicing emergency or

complete shutdown of the unit When power

is cut off from the unit compressors using

crankcase heaters cannot prevent refrigerant

migration This means the compressor may

cool down and liquid refrigerant may

accumulate in the compressor Since the

compressor is designed to pump refrigerant

gas damage may occur when power is

restored

If power to the unit must be off for more

than an hour turn the thermostat system

switch to ldquoOffrdquo or turn the unit off at the

control panel and then cut off the main

power supply Leave the unit off until the

main power supply has been turned on again

for at least 24 hours This will give the

crankcase heater time to clear any liquid

accumulation out of the compressor before it

is required to run

Always control the system from the

thermostat or control panel never at the

main power supply except for servicing

emergency or complete shutdown of the

unit

The standard compressors must be on a

minimum of 5 minutes and off for a

minimum of 5 minutes The cycle rate must

be no more than 6 starts per hour

The variable capacity compressors must be

on a minimum of 3 minutes and off for a

minimum of 3 minutes The cycle rate must

be no more than 10 starts per hour

The compressor life will be seriously

shortened by reduced lubrication and the

pumping of excessive amounts of liquid oil

and liquid refrigerant

CRANKCASE HEATER OPERATION

Units are equipped with compressor crankcase heaters which should be energized at least 24 hours prior to cooling operation to clear any liquid refrigerant from the compressors

CAUTION

13

Note Low Ambient Operation

Units without a low ambient option such as

condenser fan cycling or the 0degF low

ambient option will not operate in the

cooling mode of operation properly when

the outdoor temperature is below 55degF Low

ambient andor air handling unit economizer

options are recommended if cooling

operation below 55degF is expected

Note Multiple Systems with Multiple

Thermostats

When several heating and cooling split

systems are used to condition a space all

thermostat switches must be set in either

heating mode cooling mode or off Do not

leave part of the systems switched to the

opposite mode Cooling only systems should

be switched off at the thermostat during the

heating season

Wiring Diagrams

Unit specific wiring diagram is laminated in

plastic and located inside the controls

compartment door

General Maintenance

When the initial startup is made and on a

periodic schedule during operation it is

necessary to perform routine service checks

on the performance of the condensing unit

This includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

14

Installation

AAON equipment has been designed for

quick and easy installation

Lifting the Unit

CB Series condensing units have channels

underneath the base which provide lifting

access to the underside of the equipment and

allow moving and placement without

physical damage

Figure 1 ndash Forklift Channels amp Access Panel

Dollies andor carts are recommended to lift

and place the unit to prevent damage to the

equipment and injury to the installer

Care should be taken if using spreader bars

blocking or other lifting devices to prevent

any damage to the cabinet coil or

condensing fans

Before lifting unit be sure that all shipping

material has been removed from unit

Hoist unit to a point directly above the

condenser pad and lower unit into the

proper place Unit may also be positioned

with a dolly When the unit is in place

remove the dolly or lifting device Make

sure the unit is properly seated and level

Locating Unit

CB Series condensing units are designed for

outdoor application and placement at ground

level or on a rooftop Units must be placed

on a level and solid foundation that can

support the unitrsquos weight

When rooftop mounted a steel frame must

be provided that will support the unit above

the roof itself for load distribution

When installed at ground level a one-piece

concrete slab or composite condenser pad

should be used with footings that extend

below the frost line (a substantial base that

will not settle) Slab should be surrounded

by a graveled area for proper drainage and

should not adjoin the building as sound and

vibration may be transmitted to the

structure Care must also be taken to protect

the coils and fins from damage due to

vandalism or other hazards

Airflow to and from the condensing unit

must not be restricted Coils and fans must

be free of any obstructions and debris in

order to start and operate properly with a

correct amount of airflow Obstruction to air

flow will result in decreased performance

and efficiency

The installation position must provide at

least one foot of clearance from the wall for

proper air flow to the coils When multiple

units are mounted adjacent to each other the

clearance required between them is three

feet

Service compartment must be accessible for

periodic servicing of controls safety

devices and refrigerant serviceshutoff

valves At least two feet of clearance on this

Incorrect lifting can cause damage to the unit

CAUTION

15

corner of the unit is recommended for

service

Figure 2 ndash Condensing Unit Clearances

Condensing units should not be installed in

an enclosure or pit that is deeper than the

height of the unit When recessed

installation is necessary the clearance to

maintain proper airflow is at least three feet

CB Series condensing units are single

circuited with vertical air discharge There

must be no obstruction above the equipment

Do not place the unit under an overhang

Placement relative to the building air intakes

and other structures must be carefully

selected Consider the effects of outdoor fan

noise on conditioned space and any adjacent

occupied space It is recommended that the

unit be placed so that discharge does not

blow toward windows less than 25 feet

away

Heat pumps require special location

consideration in areas where snow

accumulation can become an obstruction

and in areas with prolonged continuous

subfreezing temperatures Heat pump unit

bases are cutout under the outdoor coil to

permit drainage of frost accumulation The

unit must be situated to permit free

unobstructed drainage of the defrost water

and ice A minimum 3 inches clearance

under the outdoor coil is required in the

milder climates In more severe weather

locations it is recommended that the unit be

elevated to allow unobstructed drainage and

airflow

Table 1 - Recommended Elevation

Minimums

Design

Temperature

Suggest Minimum

Elevation

+15 F and above 3rdquo

-5 F to +17 F 8rdquo

Below -5 F 12rdquo

Mounting Isolation

For roof mounted applications or anytime

vibration transmission is a factor vibration

isolators may be used

Access Panel

Access panel is provided to electrical

compartment To remove the panel

unscrew the four screws

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

16

Electrical

Verify the unit nameplate agrees with the

power supply Connect power and control

field wiring as shown on the unit wiring

diagram provided with the unit

Route power and control wiring separately

through the utility entry right above the

service valves Do not run power and signal

wires in the same conduit

Figure 3 ndash Utility Entry

Size supply conductors based on the unit

MCA rating Supply conductors must be

rated a minimum of 75degC

Protect the branch circuit in accordance with

code requirements The unit must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Note Units are factory wired for 208V

230V 460V or 575V In some units the

208V and 230V options may also be

provided in single or three phase

configurations The transformer

configuration must be checked by a

qualified technician prior to startup

Wire power leads to the unit terminal block

All wiring beyond this point has been done

by the manufacturer and cannot be modified

without affecting the units agencysafety

certification

All units require field supplied electrical

overcurrent and short circuit protection

Device must not be sized larger than the

Maximum Overcurrent Protection (MOP)

shown on the unit nameplate

Codes may require a disconnect switch be

within sight of the unit

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Before attempting to perform any installation service or maintenance shut off all electrical power to the unit at the disconnect switches Unit may have multiple power supplies Failure to disconnect power could result in dangerous operation serious injury death or property damage

WARNING

17

It is recommended that the field installed

overcurrent protection or disconnect switch

not be installed on the unit

Supply voltage must be within the minmax

range shown on the unit nameplate

Available short circuit current should not

exceed the short circuit current rating

(SCCR) shown on the unit nameplate

Three phase voltage imbalance will cause

motor overheating and premature failure

The maximum allowable imbalance is 20

Voltage imbalance is defined as 100 times

the maximum deviation from the average

voltage divided by the average voltage

Example

(221V+230V+227V)3 = 226V then

100(226V-221V)226V = 22 which

exceeds the allowable imbalance

Check voltage imbalance at the unit

disconnect switch and at the compressor

terminal Contact your local power company

for line voltage corrections

Installing contractor must check for proper

motor rotation and check blower motor

amperage listed on the motor nameplate is

not exceeded

Wire control signals to the unitrsquos low

voltage terminal block located in the

controls compartment

If any factory installed wiring must be

replaced use a minimum 105degC type AWM

insulated conductors

Thermostat

If a thermostat is used for unit control

thermostat should be located on an inside

wall 4-5 feet above the floor where it will

not be subjected to drafts sun exposure or

heat from electrical fixtures or appliances

Follow thermostat manufacturerrsquos

instructions for general installation

procedure

Thermostat control wiring size must be large

enough to prevent excess voltage drop and

ensure proper operation

All external devices must be powered via a

separate external power supply

Units with the modulating hot gas reheat

dehumidification feature must use a

humidistat or a thermostat with a normally

closed (NC) dehumidification option The

following thermostats have been approved

for usage with the dehumidification feature

Robertshawreg 9825i2 Thermostat

Honeywell VisionPROreg IAQ Thermostat

AAON Mini Controller

Three phase voltage imbalance will cause motor overheating and premature failure

CAUTION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 12: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

12

may have been placed inside the unit cabinet

for security Installers and owners should

secure all doors with locks or nuts and bolts

to prevent unauthorized access

The warranty card must be completed in full

and returned to AAON not more than 3

months after the unit is delivered

Storage

If installation will not occur immediately

following delivery store equipment in a dry

protected area away from construction

traffic and in the proper orientation as

marked on the packaging with all internal

packaging in place Secure all loose-shipped

items

Direct Expansion (DX) Condensing Units

CB Series condensing units are factory

assembled and wired including a full charge

of R-410A refrigerant for up to 25 feet of

line set Systems with the modulating hot

gas reheat option will require refrigerant to

be field added because of the additional

refrigerant components and piping

associated with the system

Failure to observe the following instructions

may result in premature failure of your

system and possible voiding of the

warranty

Never cut off the main power supply to the

unit except for servicing emergency or

complete shutdown of the unit When power

is cut off from the unit compressors using

crankcase heaters cannot prevent refrigerant

migration This means the compressor may

cool down and liquid refrigerant may

accumulate in the compressor Since the

compressor is designed to pump refrigerant

gas damage may occur when power is

restored

If power to the unit must be off for more

than an hour turn the thermostat system

switch to ldquoOffrdquo or turn the unit off at the

control panel and then cut off the main

power supply Leave the unit off until the

main power supply has been turned on again

for at least 24 hours This will give the

crankcase heater time to clear any liquid

accumulation out of the compressor before it

is required to run

Always control the system from the

thermostat or control panel never at the

main power supply except for servicing

emergency or complete shutdown of the

unit

The standard compressors must be on a

minimum of 5 minutes and off for a

minimum of 5 minutes The cycle rate must

be no more than 6 starts per hour

The variable capacity compressors must be

on a minimum of 3 minutes and off for a

minimum of 3 minutes The cycle rate must

be no more than 10 starts per hour

The compressor life will be seriously

shortened by reduced lubrication and the

pumping of excessive amounts of liquid oil

and liquid refrigerant

CRANKCASE HEATER OPERATION

Units are equipped with compressor crankcase heaters which should be energized at least 24 hours prior to cooling operation to clear any liquid refrigerant from the compressors

CAUTION

13

Note Low Ambient Operation

Units without a low ambient option such as

condenser fan cycling or the 0degF low

ambient option will not operate in the

cooling mode of operation properly when

the outdoor temperature is below 55degF Low

ambient andor air handling unit economizer

options are recommended if cooling

operation below 55degF is expected

Note Multiple Systems with Multiple

Thermostats

When several heating and cooling split

systems are used to condition a space all

thermostat switches must be set in either

heating mode cooling mode or off Do not

leave part of the systems switched to the

opposite mode Cooling only systems should

be switched off at the thermostat during the

heating season

Wiring Diagrams

Unit specific wiring diagram is laminated in

plastic and located inside the controls

compartment door

General Maintenance

When the initial startup is made and on a

periodic schedule during operation it is

necessary to perform routine service checks

on the performance of the condensing unit

This includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

14

Installation

AAON equipment has been designed for

quick and easy installation

Lifting the Unit

CB Series condensing units have channels

underneath the base which provide lifting

access to the underside of the equipment and

allow moving and placement without

physical damage

Figure 1 ndash Forklift Channels amp Access Panel

Dollies andor carts are recommended to lift

and place the unit to prevent damage to the

equipment and injury to the installer

Care should be taken if using spreader bars

blocking or other lifting devices to prevent

any damage to the cabinet coil or

condensing fans

Before lifting unit be sure that all shipping

material has been removed from unit

Hoist unit to a point directly above the

condenser pad and lower unit into the

proper place Unit may also be positioned

with a dolly When the unit is in place

remove the dolly or lifting device Make

sure the unit is properly seated and level

Locating Unit

CB Series condensing units are designed for

outdoor application and placement at ground

level or on a rooftop Units must be placed

on a level and solid foundation that can

support the unitrsquos weight

When rooftop mounted a steel frame must

be provided that will support the unit above

the roof itself for load distribution

When installed at ground level a one-piece

concrete slab or composite condenser pad

should be used with footings that extend

below the frost line (a substantial base that

will not settle) Slab should be surrounded

by a graveled area for proper drainage and

should not adjoin the building as sound and

vibration may be transmitted to the

structure Care must also be taken to protect

the coils and fins from damage due to

vandalism or other hazards

Airflow to and from the condensing unit

must not be restricted Coils and fans must

be free of any obstructions and debris in

order to start and operate properly with a

correct amount of airflow Obstruction to air

flow will result in decreased performance

and efficiency

The installation position must provide at

least one foot of clearance from the wall for

proper air flow to the coils When multiple

units are mounted adjacent to each other the

clearance required between them is three

feet

Service compartment must be accessible for

periodic servicing of controls safety

devices and refrigerant serviceshutoff

valves At least two feet of clearance on this

Incorrect lifting can cause damage to the unit

CAUTION

15

corner of the unit is recommended for

service

Figure 2 ndash Condensing Unit Clearances

Condensing units should not be installed in

an enclosure or pit that is deeper than the

height of the unit When recessed

installation is necessary the clearance to

maintain proper airflow is at least three feet

CB Series condensing units are single

circuited with vertical air discharge There

must be no obstruction above the equipment

Do not place the unit under an overhang

Placement relative to the building air intakes

and other structures must be carefully

selected Consider the effects of outdoor fan

noise on conditioned space and any adjacent

occupied space It is recommended that the

unit be placed so that discharge does not

blow toward windows less than 25 feet

away

Heat pumps require special location

consideration in areas where snow

accumulation can become an obstruction

and in areas with prolonged continuous

subfreezing temperatures Heat pump unit

bases are cutout under the outdoor coil to

permit drainage of frost accumulation The

unit must be situated to permit free

unobstructed drainage of the defrost water

and ice A minimum 3 inches clearance

under the outdoor coil is required in the

milder climates In more severe weather

locations it is recommended that the unit be

elevated to allow unobstructed drainage and

airflow

Table 1 - Recommended Elevation

Minimums

Design

Temperature

Suggest Minimum

Elevation

+15 F and above 3rdquo

-5 F to +17 F 8rdquo

Below -5 F 12rdquo

Mounting Isolation

For roof mounted applications or anytime

vibration transmission is a factor vibration

isolators may be used

Access Panel

Access panel is provided to electrical

compartment To remove the panel

unscrew the four screws

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

16

Electrical

Verify the unit nameplate agrees with the

power supply Connect power and control

field wiring as shown on the unit wiring

diagram provided with the unit

Route power and control wiring separately

through the utility entry right above the

service valves Do not run power and signal

wires in the same conduit

Figure 3 ndash Utility Entry

Size supply conductors based on the unit

MCA rating Supply conductors must be

rated a minimum of 75degC

Protect the branch circuit in accordance with

code requirements The unit must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Note Units are factory wired for 208V

230V 460V or 575V In some units the

208V and 230V options may also be

provided in single or three phase

configurations The transformer

configuration must be checked by a

qualified technician prior to startup

Wire power leads to the unit terminal block

All wiring beyond this point has been done

by the manufacturer and cannot be modified

without affecting the units agencysafety

certification

All units require field supplied electrical

overcurrent and short circuit protection

Device must not be sized larger than the

Maximum Overcurrent Protection (MOP)

shown on the unit nameplate

Codes may require a disconnect switch be

within sight of the unit

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Before attempting to perform any installation service or maintenance shut off all electrical power to the unit at the disconnect switches Unit may have multiple power supplies Failure to disconnect power could result in dangerous operation serious injury death or property damage

WARNING

17

It is recommended that the field installed

overcurrent protection or disconnect switch

not be installed on the unit

Supply voltage must be within the minmax

range shown on the unit nameplate

Available short circuit current should not

exceed the short circuit current rating

(SCCR) shown on the unit nameplate

Three phase voltage imbalance will cause

motor overheating and premature failure

The maximum allowable imbalance is 20

Voltage imbalance is defined as 100 times

the maximum deviation from the average

voltage divided by the average voltage

Example

(221V+230V+227V)3 = 226V then

100(226V-221V)226V = 22 which

exceeds the allowable imbalance

Check voltage imbalance at the unit

disconnect switch and at the compressor

terminal Contact your local power company

for line voltage corrections

Installing contractor must check for proper

motor rotation and check blower motor

amperage listed on the motor nameplate is

not exceeded

Wire control signals to the unitrsquos low

voltage terminal block located in the

controls compartment

If any factory installed wiring must be

replaced use a minimum 105degC type AWM

insulated conductors

Thermostat

If a thermostat is used for unit control

thermostat should be located on an inside

wall 4-5 feet above the floor where it will

not be subjected to drafts sun exposure or

heat from electrical fixtures or appliances

Follow thermostat manufacturerrsquos

instructions for general installation

procedure

Thermostat control wiring size must be large

enough to prevent excess voltage drop and

ensure proper operation

All external devices must be powered via a

separate external power supply

Units with the modulating hot gas reheat

dehumidification feature must use a

humidistat or a thermostat with a normally

closed (NC) dehumidification option The

following thermostats have been approved

for usage with the dehumidification feature

Robertshawreg 9825i2 Thermostat

Honeywell VisionPROreg IAQ Thermostat

AAON Mini Controller

Three phase voltage imbalance will cause motor overheating and premature failure

CAUTION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 13: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

13

Note Low Ambient Operation

Units without a low ambient option such as

condenser fan cycling or the 0degF low

ambient option will not operate in the

cooling mode of operation properly when

the outdoor temperature is below 55degF Low

ambient andor air handling unit economizer

options are recommended if cooling

operation below 55degF is expected

Note Multiple Systems with Multiple

Thermostats

When several heating and cooling split

systems are used to condition a space all

thermostat switches must be set in either

heating mode cooling mode or off Do not

leave part of the systems switched to the

opposite mode Cooling only systems should

be switched off at the thermostat during the

heating season

Wiring Diagrams

Unit specific wiring diagram is laminated in

plastic and located inside the controls

compartment door

General Maintenance

When the initial startup is made and on a

periodic schedule during operation it is

necessary to perform routine service checks

on the performance of the condensing unit

This includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

14

Installation

AAON equipment has been designed for

quick and easy installation

Lifting the Unit

CB Series condensing units have channels

underneath the base which provide lifting

access to the underside of the equipment and

allow moving and placement without

physical damage

Figure 1 ndash Forklift Channels amp Access Panel

Dollies andor carts are recommended to lift

and place the unit to prevent damage to the

equipment and injury to the installer

Care should be taken if using spreader bars

blocking or other lifting devices to prevent

any damage to the cabinet coil or

condensing fans

Before lifting unit be sure that all shipping

material has been removed from unit

Hoist unit to a point directly above the

condenser pad and lower unit into the

proper place Unit may also be positioned

with a dolly When the unit is in place

remove the dolly or lifting device Make

sure the unit is properly seated and level

Locating Unit

CB Series condensing units are designed for

outdoor application and placement at ground

level or on a rooftop Units must be placed

on a level and solid foundation that can

support the unitrsquos weight

When rooftop mounted a steel frame must

be provided that will support the unit above

the roof itself for load distribution

When installed at ground level a one-piece

concrete slab or composite condenser pad

should be used with footings that extend

below the frost line (a substantial base that

will not settle) Slab should be surrounded

by a graveled area for proper drainage and

should not adjoin the building as sound and

vibration may be transmitted to the

structure Care must also be taken to protect

the coils and fins from damage due to

vandalism or other hazards

Airflow to and from the condensing unit

must not be restricted Coils and fans must

be free of any obstructions and debris in

order to start and operate properly with a

correct amount of airflow Obstruction to air

flow will result in decreased performance

and efficiency

The installation position must provide at

least one foot of clearance from the wall for

proper air flow to the coils When multiple

units are mounted adjacent to each other the

clearance required between them is three

feet

Service compartment must be accessible for

periodic servicing of controls safety

devices and refrigerant serviceshutoff

valves At least two feet of clearance on this

Incorrect lifting can cause damage to the unit

CAUTION

15

corner of the unit is recommended for

service

Figure 2 ndash Condensing Unit Clearances

Condensing units should not be installed in

an enclosure or pit that is deeper than the

height of the unit When recessed

installation is necessary the clearance to

maintain proper airflow is at least three feet

CB Series condensing units are single

circuited with vertical air discharge There

must be no obstruction above the equipment

Do not place the unit under an overhang

Placement relative to the building air intakes

and other structures must be carefully

selected Consider the effects of outdoor fan

noise on conditioned space and any adjacent

occupied space It is recommended that the

unit be placed so that discharge does not

blow toward windows less than 25 feet

away

Heat pumps require special location

consideration in areas where snow

accumulation can become an obstruction

and in areas with prolonged continuous

subfreezing temperatures Heat pump unit

bases are cutout under the outdoor coil to

permit drainage of frost accumulation The

unit must be situated to permit free

unobstructed drainage of the defrost water

and ice A minimum 3 inches clearance

under the outdoor coil is required in the

milder climates In more severe weather

locations it is recommended that the unit be

elevated to allow unobstructed drainage and

airflow

Table 1 - Recommended Elevation

Minimums

Design

Temperature

Suggest Minimum

Elevation

+15 F and above 3rdquo

-5 F to +17 F 8rdquo

Below -5 F 12rdquo

Mounting Isolation

For roof mounted applications or anytime

vibration transmission is a factor vibration

isolators may be used

Access Panel

Access panel is provided to electrical

compartment To remove the panel

unscrew the four screws

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

16

Electrical

Verify the unit nameplate agrees with the

power supply Connect power and control

field wiring as shown on the unit wiring

diagram provided with the unit

Route power and control wiring separately

through the utility entry right above the

service valves Do not run power and signal

wires in the same conduit

Figure 3 ndash Utility Entry

Size supply conductors based on the unit

MCA rating Supply conductors must be

rated a minimum of 75degC

Protect the branch circuit in accordance with

code requirements The unit must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Note Units are factory wired for 208V

230V 460V or 575V In some units the

208V and 230V options may also be

provided in single or three phase

configurations The transformer

configuration must be checked by a

qualified technician prior to startup

Wire power leads to the unit terminal block

All wiring beyond this point has been done

by the manufacturer and cannot be modified

without affecting the units agencysafety

certification

All units require field supplied electrical

overcurrent and short circuit protection

Device must not be sized larger than the

Maximum Overcurrent Protection (MOP)

shown on the unit nameplate

Codes may require a disconnect switch be

within sight of the unit

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Before attempting to perform any installation service or maintenance shut off all electrical power to the unit at the disconnect switches Unit may have multiple power supplies Failure to disconnect power could result in dangerous operation serious injury death or property damage

WARNING

17

It is recommended that the field installed

overcurrent protection or disconnect switch

not be installed on the unit

Supply voltage must be within the minmax

range shown on the unit nameplate

Available short circuit current should not

exceed the short circuit current rating

(SCCR) shown on the unit nameplate

Three phase voltage imbalance will cause

motor overheating and premature failure

The maximum allowable imbalance is 20

Voltage imbalance is defined as 100 times

the maximum deviation from the average

voltage divided by the average voltage

Example

(221V+230V+227V)3 = 226V then

100(226V-221V)226V = 22 which

exceeds the allowable imbalance

Check voltage imbalance at the unit

disconnect switch and at the compressor

terminal Contact your local power company

for line voltage corrections

Installing contractor must check for proper

motor rotation and check blower motor

amperage listed on the motor nameplate is

not exceeded

Wire control signals to the unitrsquos low

voltage terminal block located in the

controls compartment

If any factory installed wiring must be

replaced use a minimum 105degC type AWM

insulated conductors

Thermostat

If a thermostat is used for unit control

thermostat should be located on an inside

wall 4-5 feet above the floor where it will

not be subjected to drafts sun exposure or

heat from electrical fixtures or appliances

Follow thermostat manufacturerrsquos

instructions for general installation

procedure

Thermostat control wiring size must be large

enough to prevent excess voltage drop and

ensure proper operation

All external devices must be powered via a

separate external power supply

Units with the modulating hot gas reheat

dehumidification feature must use a

humidistat or a thermostat with a normally

closed (NC) dehumidification option The

following thermostats have been approved

for usage with the dehumidification feature

Robertshawreg 9825i2 Thermostat

Honeywell VisionPROreg IAQ Thermostat

AAON Mini Controller

Three phase voltage imbalance will cause motor overheating and premature failure

CAUTION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 14: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

14

Installation

AAON equipment has been designed for

quick and easy installation

Lifting the Unit

CB Series condensing units have channels

underneath the base which provide lifting

access to the underside of the equipment and

allow moving and placement without

physical damage

Figure 1 ndash Forklift Channels amp Access Panel

Dollies andor carts are recommended to lift

and place the unit to prevent damage to the

equipment and injury to the installer

Care should be taken if using spreader bars

blocking or other lifting devices to prevent

any damage to the cabinet coil or

condensing fans

Before lifting unit be sure that all shipping

material has been removed from unit

Hoist unit to a point directly above the

condenser pad and lower unit into the

proper place Unit may also be positioned

with a dolly When the unit is in place

remove the dolly or lifting device Make

sure the unit is properly seated and level

Locating Unit

CB Series condensing units are designed for

outdoor application and placement at ground

level or on a rooftop Units must be placed

on a level and solid foundation that can

support the unitrsquos weight

When rooftop mounted a steel frame must

be provided that will support the unit above

the roof itself for load distribution

When installed at ground level a one-piece

concrete slab or composite condenser pad

should be used with footings that extend

below the frost line (a substantial base that

will not settle) Slab should be surrounded

by a graveled area for proper drainage and

should not adjoin the building as sound and

vibration may be transmitted to the

structure Care must also be taken to protect

the coils and fins from damage due to

vandalism or other hazards

Airflow to and from the condensing unit

must not be restricted Coils and fans must

be free of any obstructions and debris in

order to start and operate properly with a

correct amount of airflow Obstruction to air

flow will result in decreased performance

and efficiency

The installation position must provide at

least one foot of clearance from the wall for

proper air flow to the coils When multiple

units are mounted adjacent to each other the

clearance required between them is three

feet

Service compartment must be accessible for

periodic servicing of controls safety

devices and refrigerant serviceshutoff

valves At least two feet of clearance on this

Incorrect lifting can cause damage to the unit

CAUTION

15

corner of the unit is recommended for

service

Figure 2 ndash Condensing Unit Clearances

Condensing units should not be installed in

an enclosure or pit that is deeper than the

height of the unit When recessed

installation is necessary the clearance to

maintain proper airflow is at least three feet

CB Series condensing units are single

circuited with vertical air discharge There

must be no obstruction above the equipment

Do not place the unit under an overhang

Placement relative to the building air intakes

and other structures must be carefully

selected Consider the effects of outdoor fan

noise on conditioned space and any adjacent

occupied space It is recommended that the

unit be placed so that discharge does not

blow toward windows less than 25 feet

away

Heat pumps require special location

consideration in areas where snow

accumulation can become an obstruction

and in areas with prolonged continuous

subfreezing temperatures Heat pump unit

bases are cutout under the outdoor coil to

permit drainage of frost accumulation The

unit must be situated to permit free

unobstructed drainage of the defrost water

and ice A minimum 3 inches clearance

under the outdoor coil is required in the

milder climates In more severe weather

locations it is recommended that the unit be

elevated to allow unobstructed drainage and

airflow

Table 1 - Recommended Elevation

Minimums

Design

Temperature

Suggest Minimum

Elevation

+15 F and above 3rdquo

-5 F to +17 F 8rdquo

Below -5 F 12rdquo

Mounting Isolation

For roof mounted applications or anytime

vibration transmission is a factor vibration

isolators may be used

Access Panel

Access panel is provided to electrical

compartment To remove the panel

unscrew the four screws

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

16

Electrical

Verify the unit nameplate agrees with the

power supply Connect power and control

field wiring as shown on the unit wiring

diagram provided with the unit

Route power and control wiring separately

through the utility entry right above the

service valves Do not run power and signal

wires in the same conduit

Figure 3 ndash Utility Entry

Size supply conductors based on the unit

MCA rating Supply conductors must be

rated a minimum of 75degC

Protect the branch circuit in accordance with

code requirements The unit must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Note Units are factory wired for 208V

230V 460V or 575V In some units the

208V and 230V options may also be

provided in single or three phase

configurations The transformer

configuration must be checked by a

qualified technician prior to startup

Wire power leads to the unit terminal block

All wiring beyond this point has been done

by the manufacturer and cannot be modified

without affecting the units agencysafety

certification

All units require field supplied electrical

overcurrent and short circuit protection

Device must not be sized larger than the

Maximum Overcurrent Protection (MOP)

shown on the unit nameplate

Codes may require a disconnect switch be

within sight of the unit

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Before attempting to perform any installation service or maintenance shut off all electrical power to the unit at the disconnect switches Unit may have multiple power supplies Failure to disconnect power could result in dangerous operation serious injury death or property damage

WARNING

17

It is recommended that the field installed

overcurrent protection or disconnect switch

not be installed on the unit

Supply voltage must be within the minmax

range shown on the unit nameplate

Available short circuit current should not

exceed the short circuit current rating

(SCCR) shown on the unit nameplate

Three phase voltage imbalance will cause

motor overheating and premature failure

The maximum allowable imbalance is 20

Voltage imbalance is defined as 100 times

the maximum deviation from the average

voltage divided by the average voltage

Example

(221V+230V+227V)3 = 226V then

100(226V-221V)226V = 22 which

exceeds the allowable imbalance

Check voltage imbalance at the unit

disconnect switch and at the compressor

terminal Contact your local power company

for line voltage corrections

Installing contractor must check for proper

motor rotation and check blower motor

amperage listed on the motor nameplate is

not exceeded

Wire control signals to the unitrsquos low

voltage terminal block located in the

controls compartment

If any factory installed wiring must be

replaced use a minimum 105degC type AWM

insulated conductors

Thermostat

If a thermostat is used for unit control

thermostat should be located on an inside

wall 4-5 feet above the floor where it will

not be subjected to drafts sun exposure or

heat from electrical fixtures or appliances

Follow thermostat manufacturerrsquos

instructions for general installation

procedure

Thermostat control wiring size must be large

enough to prevent excess voltage drop and

ensure proper operation

All external devices must be powered via a

separate external power supply

Units with the modulating hot gas reheat

dehumidification feature must use a

humidistat or a thermostat with a normally

closed (NC) dehumidification option The

following thermostats have been approved

for usage with the dehumidification feature

Robertshawreg 9825i2 Thermostat

Honeywell VisionPROreg IAQ Thermostat

AAON Mini Controller

Three phase voltage imbalance will cause motor overheating and premature failure

CAUTION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 15: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

15

corner of the unit is recommended for

service

Figure 2 ndash Condensing Unit Clearances

Condensing units should not be installed in

an enclosure or pit that is deeper than the

height of the unit When recessed

installation is necessary the clearance to

maintain proper airflow is at least three feet

CB Series condensing units are single

circuited with vertical air discharge There

must be no obstruction above the equipment

Do not place the unit under an overhang

Placement relative to the building air intakes

and other structures must be carefully

selected Consider the effects of outdoor fan

noise on conditioned space and any adjacent

occupied space It is recommended that the

unit be placed so that discharge does not

blow toward windows less than 25 feet

away

Heat pumps require special location

consideration in areas where snow

accumulation can become an obstruction

and in areas with prolonged continuous

subfreezing temperatures Heat pump unit

bases are cutout under the outdoor coil to

permit drainage of frost accumulation The

unit must be situated to permit free

unobstructed drainage of the defrost water

and ice A minimum 3 inches clearance

under the outdoor coil is required in the

milder climates In more severe weather

locations it is recommended that the unit be

elevated to allow unobstructed drainage and

airflow

Table 1 - Recommended Elevation

Minimums

Design

Temperature

Suggest Minimum

Elevation

+15 F and above 3rdquo

-5 F to +17 F 8rdquo

Below -5 F 12rdquo

Mounting Isolation

For roof mounted applications or anytime

vibration transmission is a factor vibration

isolators may be used

Access Panel

Access panel is provided to electrical

compartment To remove the panel

unscrew the four screws

PVC PIPING

PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) are vulnerable to attack by certain chemicals Polyolester (POE) oils used with R-410A and other refrigerants even in trace amounts in a PVC or CPVC piping system will result in stress cracking of the piping and fittings and complete piping system failure

CAUTION

16

Electrical

Verify the unit nameplate agrees with the

power supply Connect power and control

field wiring as shown on the unit wiring

diagram provided with the unit

Route power and control wiring separately

through the utility entry right above the

service valves Do not run power and signal

wires in the same conduit

Figure 3 ndash Utility Entry

Size supply conductors based on the unit

MCA rating Supply conductors must be

rated a minimum of 75degC

Protect the branch circuit in accordance with

code requirements The unit must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Note Units are factory wired for 208V

230V 460V or 575V In some units the

208V and 230V options may also be

provided in single or three phase

configurations The transformer

configuration must be checked by a

qualified technician prior to startup

Wire power leads to the unit terminal block

All wiring beyond this point has been done

by the manufacturer and cannot be modified

without affecting the units agencysafety

certification

All units require field supplied electrical

overcurrent and short circuit protection

Device must not be sized larger than the

Maximum Overcurrent Protection (MOP)

shown on the unit nameplate

Codes may require a disconnect switch be

within sight of the unit

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Before attempting to perform any installation service or maintenance shut off all electrical power to the unit at the disconnect switches Unit may have multiple power supplies Failure to disconnect power could result in dangerous operation serious injury death or property damage

WARNING

17

It is recommended that the field installed

overcurrent protection or disconnect switch

not be installed on the unit

Supply voltage must be within the minmax

range shown on the unit nameplate

Available short circuit current should not

exceed the short circuit current rating

(SCCR) shown on the unit nameplate

Three phase voltage imbalance will cause

motor overheating and premature failure

The maximum allowable imbalance is 20

Voltage imbalance is defined as 100 times

the maximum deviation from the average

voltage divided by the average voltage

Example

(221V+230V+227V)3 = 226V then

100(226V-221V)226V = 22 which

exceeds the allowable imbalance

Check voltage imbalance at the unit

disconnect switch and at the compressor

terminal Contact your local power company

for line voltage corrections

Installing contractor must check for proper

motor rotation and check blower motor

amperage listed on the motor nameplate is

not exceeded

Wire control signals to the unitrsquos low

voltage terminal block located in the

controls compartment

If any factory installed wiring must be

replaced use a minimum 105degC type AWM

insulated conductors

Thermostat

If a thermostat is used for unit control

thermostat should be located on an inside

wall 4-5 feet above the floor where it will

not be subjected to drafts sun exposure or

heat from electrical fixtures or appliances

Follow thermostat manufacturerrsquos

instructions for general installation

procedure

Thermostat control wiring size must be large

enough to prevent excess voltage drop and

ensure proper operation

All external devices must be powered via a

separate external power supply

Units with the modulating hot gas reheat

dehumidification feature must use a

humidistat or a thermostat with a normally

closed (NC) dehumidification option The

following thermostats have been approved

for usage with the dehumidification feature

Robertshawreg 9825i2 Thermostat

Honeywell VisionPROreg IAQ Thermostat

AAON Mini Controller

Three phase voltage imbalance will cause motor overheating and premature failure

CAUTION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 16: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

16

Electrical

Verify the unit nameplate agrees with the

power supply Connect power and control

field wiring as shown on the unit wiring

diagram provided with the unit

Route power and control wiring separately

through the utility entry right above the

service valves Do not run power and signal

wires in the same conduit

Figure 3 ndash Utility Entry

Size supply conductors based on the unit

MCA rating Supply conductors must be

rated a minimum of 75degC

Protect the branch circuit in accordance with

code requirements The unit must be

electrically grounded in accordance with

local codes or in the absence of local codes

the current National Electric Code

ANSINFPA 70 or the current Canadian

Electrical Code CSA C221

Note Units are factory wired for 208V

230V 460V or 575V In some units the

208V and 230V options may also be

provided in single or three phase

configurations The transformer

configuration must be checked by a

qualified technician prior to startup

Wire power leads to the unit terminal block

All wiring beyond this point has been done

by the manufacturer and cannot be modified

without affecting the units agencysafety

certification

All units require field supplied electrical

overcurrent and short circuit protection

Device must not be sized larger than the

Maximum Overcurrent Protection (MOP)

shown on the unit nameplate

Codes may require a disconnect switch be

within sight of the unit

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Before attempting to perform any installation service or maintenance shut off all electrical power to the unit at the disconnect switches Unit may have multiple power supplies Failure to disconnect power could result in dangerous operation serious injury death or property damage

WARNING

17

It is recommended that the field installed

overcurrent protection or disconnect switch

not be installed on the unit

Supply voltage must be within the minmax

range shown on the unit nameplate

Available short circuit current should not

exceed the short circuit current rating

(SCCR) shown on the unit nameplate

Three phase voltage imbalance will cause

motor overheating and premature failure

The maximum allowable imbalance is 20

Voltage imbalance is defined as 100 times

the maximum deviation from the average

voltage divided by the average voltage

Example

(221V+230V+227V)3 = 226V then

100(226V-221V)226V = 22 which

exceeds the allowable imbalance

Check voltage imbalance at the unit

disconnect switch and at the compressor

terminal Contact your local power company

for line voltage corrections

Installing contractor must check for proper

motor rotation and check blower motor

amperage listed on the motor nameplate is

not exceeded

Wire control signals to the unitrsquos low

voltage terminal block located in the

controls compartment

If any factory installed wiring must be

replaced use a minimum 105degC type AWM

insulated conductors

Thermostat

If a thermostat is used for unit control

thermostat should be located on an inside

wall 4-5 feet above the floor where it will

not be subjected to drafts sun exposure or

heat from electrical fixtures or appliances

Follow thermostat manufacturerrsquos

instructions for general installation

procedure

Thermostat control wiring size must be large

enough to prevent excess voltage drop and

ensure proper operation

All external devices must be powered via a

separate external power supply

Units with the modulating hot gas reheat

dehumidification feature must use a

humidistat or a thermostat with a normally

closed (NC) dehumidification option The

following thermostats have been approved

for usage with the dehumidification feature

Robertshawreg 9825i2 Thermostat

Honeywell VisionPROreg IAQ Thermostat

AAON Mini Controller

Three phase voltage imbalance will cause motor overheating and premature failure

CAUTION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 17: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

17

It is recommended that the field installed

overcurrent protection or disconnect switch

not be installed on the unit

Supply voltage must be within the minmax

range shown on the unit nameplate

Available short circuit current should not

exceed the short circuit current rating

(SCCR) shown on the unit nameplate

Three phase voltage imbalance will cause

motor overheating and premature failure

The maximum allowable imbalance is 20

Voltage imbalance is defined as 100 times

the maximum deviation from the average

voltage divided by the average voltage

Example

(221V+230V+227V)3 = 226V then

100(226V-221V)226V = 22 which

exceeds the allowable imbalance

Check voltage imbalance at the unit

disconnect switch and at the compressor

terminal Contact your local power company

for line voltage corrections

Installing contractor must check for proper

motor rotation and check blower motor

amperage listed on the motor nameplate is

not exceeded

Wire control signals to the unitrsquos low

voltage terminal block located in the

controls compartment

If any factory installed wiring must be

replaced use a minimum 105degC type AWM

insulated conductors

Thermostat

If a thermostat is used for unit control

thermostat should be located on an inside

wall 4-5 feet above the floor where it will

not be subjected to drafts sun exposure or

heat from electrical fixtures or appliances

Follow thermostat manufacturerrsquos

instructions for general installation

procedure

Thermostat control wiring size must be large

enough to prevent excess voltage drop and

ensure proper operation

All external devices must be powered via a

separate external power supply

Units with the modulating hot gas reheat

dehumidification feature must use a

humidistat or a thermostat with a normally

closed (NC) dehumidification option The

following thermostats have been approved

for usage with the dehumidification feature

Robertshawreg 9825i2 Thermostat

Honeywell VisionPROreg IAQ Thermostat

AAON Mini Controller

Three phase voltage imbalance will cause motor overheating and premature failure

CAUTION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 18: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

18

Refrigerant Piping

(See back of the manual for refrigerant

piping diagrams)

General

Piping from the condensing unit to the air

handler is the responsibility of the installing

contractor

Use only clean type ldquoACRrdquo copper tubing

that has been joined with high temperature

brazing alloy

The pipe or line sizes must be selected to

meet the actual installation conditions and

not simply based on the connection sizes at

the condensing unit or air handler

All CB Series condensing units are provided

with in-line shutoff valves on both the liquid

and suction lines These should remain

closed until the system is ready for start-up

after installation

Piping should conform to generally accepted

practices and codes

Upon completion of piping connection the

interconnecting piping and air handler

MUST BE evacuated to 500 microns or less

leak checked and charged with refrigerant

Determining Refrigerant Line Size

The piping between the condenser and low

side must ensure

1 Minimum pressure drop and

2 Continuous oil return and

3 Prevention of liquid refrigerant slugging

or carryover

Minimizing the refrigerant line size is

favorable from an economic perspective

reducing installation costs and reducing the

potential for leakage However as pipe

diameters narrow pressure-reducing

frictional forces increase

Excessive suction line pressure drop causes

loss of compressor capacity and increased

power usage resulting in reduced system

efficiency Excessive pressure drops in the

liquid line can cause the liquid refrigerant to

flash resulting in faulty Thermal Expansion

Valve (TXV) operation and improper

system performance In order to operate

efficiently and cost effectively while

avoiding malfunction refrigeration systems

must be designed to minimize both cost and

pressure loss

REFRIGERANT PIPING

This section is for information only and is not intended to provide all details required by the designer or installer of the refrigerant piping between the condenser or condensing unit and the air handling unit AAON Inc is not responsible for interconnecting refrigerant piping Consult ASHRAE Handbook ndash Refrigeration and ASME Standards

CAUTION

REFRIGERANT PIPING

Line sizes must be selected to meet actual installation conditions not simply based on the connection sizes at the condensing unit or air handling unit

CAUTION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 19: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

19

Equivalent Line Length

All line lengths discussed in this manual

unless specifically stated otherwise are

Equivalent Line Lengths The frictional

pressure drop through valves fittings and

accessories is determined by establishing the

equivalent length of straight pipe of the

same diameter Always use equivalent line

lengths when calculating pressure drop

Special piping provisions must be taken

when lines are run underground up vertical

risers or in excessively long line runs

Liquid Line Sizing

When sizing the liquid line it is important to

minimize the refrigerant charge to reduce

installation costs and improve system

reliability This can be achieved by

minimizing the liquid line diameter

However reducing the pipe diameter will

increase the velocity of the liquid refrigerant

which increases the frictional pressure drop

in the liquid line and causes other

undesirable effects such as noise

Maintaining the pressure in the liquid line is

critical to ensuring sufficient saturation

temperature avoiding flashing upstream of

the TXV and maintaining system

efficiency Pressure losses through the

liquid line due to frictional contact installed

accessories and vertical risers are

inevitable Maintaining adequate sub-

cooling at the condenser to overcome these

losses is the only method to ensure that

liquid refrigerant reaches the TXV

Liquid refrigerant traveling upwards in a

riser loses head pressure If the evaporator is

below the condenser and the liquid line

does not include risers the gravitational

force will increase the pressure of the liquid

refrigerant This will allow the refrigerant to

withstand greater frictional losses without

the occurrence of flashing prior to the TXV

A moisture-indicating sight glass may be

field installed in the liquid line to indicate

the occurrence of premature flashing or

moisture in the line The sight glass should

not be used to determine if the system is

properly charged Use temperature and

pressure measurements to determine

liquid sub-cooling not the sight glass

Liquid Line Routing

Care should be taken with vertical risers

When the system is shut down gravity will

pull liquid down the vertical column and

back to the condenser when it is below the

evaporator This could potentially result in

compressor flooding A check valve can be

installed in the liquid line where the liquid

column rises above the condenser to prevent

this The liquid line is typically pitched

along with the suction line or hot gas line

to minimize the complexity of the

configuration

Liquid Line Insulation

When the liquid line is routed through

regions where temperature losses are

expected no insulation is required as this

may provide additional sub-cooling to the

refrigerant When routing the liquid line

through high temperature areas insulation of

the line is appropriate to avoid loss of sub-

cooling through heat gain

Liquid Line Guidelines

In order to ensure liquid at the TXV the

sum of frictional losses and pressure loss

due to vertical rise must not exceed

available sub-cooling A commonly used

guideline to consider is a system design with

pressure losses due to friction through the

line not to exceed a corresponding 1-2degF

change in saturation temperature An

additional recommendation is that the sum

of frictional losses and pressure loss due to

vertical rise should not exceed 5degF

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 20: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

20

If the velocity of refrigerant in the liquid line

is too great it could cause excessive noise or

piping erosion The recommended

maximum velocities for liquid lines are 100

fpm from the condenser to a receiver tank to

discourage fluid backup and 300 fpm from

receiver tank to the evaporator to minimize

valve induced liquid hammer

Liquid Line Accessories

Liquid line shut off valves and filter driers

are factory provided Filter driers must be

field installed The total length equivalent of

pressure losses through valves elbows and

fittings must be considered when adding

additional components in the field It is a

good practice to utilize the fewest elbows

that will allow the mating units to be

successfully joined

A solenoid valve is recommended on lines

over 100ft in length to prevent liquid

migration when the compressors are off

The solenoid needs to be wired so that it is

open when the compressors turn on and

closed when the compressors turn off

Suction Line Sizing

The suction line is more critical than the

liquid line from a design and construction

standpoint More care must be taken to

ensure that adequate velocity is achieved to

return oil to the compressor at minimum

loading conditions However reducing the

piping diameter to increase the velocity at

minimal load can result in excessive

pressure losses capacity reduction and

noise at full load

Suction Line Routing

Pitch the suction line in the direction of flow

(about 1 foot per 120 feet of length) to

maintain oil flow towards the compressor

and keep it from flooding back into the

evaporator Crankcase heaters are provided

to keep any condensed refrigerant that

collects in the compressor from causing

damage or wear Make sure to provide

support to maintain suction line positioning

and insulate completely between the

evaporator and condensing unit

It is important to consider part load

operation when sizing suction lines At

minimum capacity refrigerant velocity may

not be adequate to return oil up the vertical

riser Decreasing the diameter of the vertical

riser will increase the velocity but also the

frictional loss

For difficult line routing applications a

double suction riser can be applied to the

situation of part load operation with a

suction riser A double suction riser is

designed to return oil at minimum load

while not incurring excessive frictional

losses at full load A double suction riser

consists of a small diameter riser in parallel

with a larger diameter riser and a trap at the

base of the large riser At minimum

capacity refrigerant velocity is not sufficient

to carry oil up both risers and it collects in

the trap effectively closing off the larger

diameter riser and diverting refrigerant up

the small riser where velocity of the

refrigerant is sufficient to maintain oil flow

At full load the mass flow clears the trap of

oil and refrigerant is carried through both

risers The smaller diameter pipe should be

sized to return oil at minimum load while

the larger diameter pipe should be sized so

that flow through both pipes provides

acceptable pressure drop at full load

SUCTION LINE SIZING

Suction line must be sized in accordance to the minimum capacity of the variable speed compressor

CAUTION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 21: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

21

A double riser used for heat pump operation

works differently than that described above

The specific volume (ft3lb) of refrigerant at

the discharge temperature (heating mode

line conditions) is significantly lower than

the specific volume at the suction

temperature (cooling mode line conditions)

To compound the issue the capacity in

heating mode is lower than the capacity in

cooling mode The discharge velocity in the

riser during heating mode is much lower

than the suction velocity during cooling

mode Often a double riser is necessary to

get acceptable velocities for the discharge

mode and acceptable velocities for the

suction mode A solenoid valve must be

added to the second riser The solenoid

valve must be wired to the reversing valve

so that the solenoid valve opens in cooling

mode and closes in heating mode See the

diagrams below

Figure 4 ndash Heat Pump Piping Schematic of

Suction Vapor Flow Down in Double Riser

Figure 5 ndash Heat Pump Piping Schematic of

Discharge Vapor Flow Up in Double Riser

Suction Line Insulation

The entire suction line should be insulated

with a minimum 1 inch thick Armaflex

insulation This prevents condensation from

forming on the line and reduces any

potential loss in capacity associated with

heat gain placing additional load on the

system

Suction Line Guidelines

For proper performance suction line

velocities less than a 4000 fpm maximum

are recommended The minimum velocity

required to return oil is dependent on the

pipe diameter however a general guideline

of 1000 fpm minimum may be applied

When suction flow is up variable capacity

compressors require a minimum velocity of

2000 fpm

Heat pump vapor lines must be checked for

suction flow (cooling mode operation) and

discharge flow (heating mode operation)

The same line must be used for both modes

of operation

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 22: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

22

In a fashion similar to the liquid line a

common guideline to consider is a system

design with pressure losses due to friction

through the line not to exceed a

corresponding 1-2degF change in saturation

temperature

At points where small pipe size can be used

to provide sufficient velocity to return oil in

vertical risers at part loads greater pressure

losses are incurred at full loads This can be

compensated for by over sizing the

horizontal runs and vertical drop sections

This will however require additional

refrigerant charge

Circuits with variable capacity scroll

compressors require suction riser traps every

10 feet

Suction Line Accessories

If the job requirements specify suction

accumulators they must be separately

purchased and field installed

Hot Gas Bypass Line

Hot Gas Bypass (HGB) is available for use

with DX systems that may experience low

suction pressure during the operating cycle

This may be due to varying load conditions

associated with VAV applications or units

supplying a large percentage of outside air

The system is designed to divert refrigerant

from the compressor discharge to the low

pressure side of the system in order to keep

the evaporator from freezing and to maintain

adequate refrigerant velocity for oil return at

minimum load

Hot discharge gas is redirected to the

evaporator inlet via an auxiliary side

connector (ASC) to false load the evaporator

when reduced suction pressure is sensed

Field piping between the condensing unit

and the evaporator is required

Hot Gas Bypass Piping Considerations for

Evaporator above Condensing Unit

Pitch the hot gas bypass line downward in

the direction of refrigerant flow toward the

evaporator

When installing hot gas bypass risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Install a sight glass in the oil drip

line for observation Run an oil return line

using 18 inch capillary tube 10 feet in

length from the oil drip line to the suction

line Connect the oil return line below the

sight glass and 1 inch above the bottom of

the oil drip line

HGB valves are adjustable Factory HGB

valve settings will be sufficient for most

applications but may require slight

adjustments for some applications including

some make up air applications

Insulate the entire length of the HGB line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Bypass Piping Considerations for

Evaporator Below Condensing Unit

The line must slope downward from the

HGB valve toward the evaporator

Hot Gas Bypass Line Guidelines

Choose a small size line to ensure oil return

and minimize refrigerant charge

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline to use is approximately 900 fpm

Hot Gas Reheat

The AAON modulating hot gas reheat

system diverts hot discharge gas from the

condenser to the air handling unit through

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 23: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

23

the hot gas line Field piping between the

condensing unit and the air handler is

required

The line delivers the hot discharge gas to the

reheat coil andor the hot gas bypass valve

so it is sized as a discharge line

Discharge lines should be sized to ensure

adequate velocity of refrigerant to ensure oil

return avoid excessive noise associated with

velocities that are too high and to minimize

efficiency losses associated with friction

Pitch the hot gas line in the direction of flow

for oil return

When installing hot gas reheat risers an oil

drip line must be provided at the lowest

point in the system The oil drip line must be

vertical its diameter should be the same as

the diameter of the riser and it should be 1

foot long Run a drip line using 18 inch

capillary tube 10 feet in length from the oil

drip line to the suction line Connect the oil

return line below the sight glass and 1 inch

above the bottom of the oil drip line

Insulate the entire length of the hot gas line

with a minimum 1 inch thick Armaflex

insulation

Hot Gas Reheat Guidelines

Maintain velocities below a maximum of

4000 fpm A general minimum velocity

guideline is 900 fpm

Predetermined Line Sizes

To aid in line sizing and selection AAON

has predetermined line sizes for the liquid

suction and hot gas lines in comfort cooling

applications

In order to generate this information the

following cycle assumptions are made

Saturated suction temperature = 50degF

Saturated condensing temperature = 125degF

Sub-cooling = 10degF Superheat = 15degF

The liquid lines have been chosen to

maintain velocities between 100 and 350

fpm The suction line diameters are selected

to limit velocities to a 4000 fpm maximum

while a minimum velocity restriction is

imposed by the ability to entrain oil up

vertical suction risers (ASHRAE Handbook

- Refrigeration)

Acceptable pressure loss criteria are applied

to each of the lines The total equivalent

length of the liquid line available is

determined such that 3degF of liquid sub-

cooling remain at the TXV This includes

the pressure losses in horizontal and vertical

sections accessories elbows etc

Recall that the available sub-cooling for the

cycle is assumed as 10degF To maintain at

least 3degF sub-cooling as a factor of safety to

avoid flashing at the TXV we consider a

maximum pressure loss equivalent to a 7degF

change in saturation temperature Pressure

losses in the suction line are not to exceed

2degF

When to Use Predetermined Line Sizing

The line sizes presented are not the only

acceptable pipe diameters they are however

appropriate for general comfort cooling

applications and satisfy common job

requirements Examine the conditions

assumptions and constraints used in the

generation of the predetermined pipe

diameters to ensure that this method is

applicable to a particular case Do not

assume that these line sizes are appropriate

for every case Consult ASHRAE

Handbook ndash Refrigeration for generally

accepted system piping practices

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 24: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

24

How to Use Predetermined Line Sizing

First read the previous section When to Use

Predetermined Line Sizing to decide if this

method is applicable Next consult Table 2

below for pipe diameters

Examine Figure 6 below to determine the

acceptable line dimensions associated with

the pipe diameters determined in Table 2

below The figure is shown as total available

riser height versus total equivalent line

length for the liquid line The curve

identifies a region of acceptable piping

configuration when the predetermined line

sizes are selected for any model in the table

A piping configuration above the curve falls

outside the assumptions used to determine

the line size and will result in a loss of sub-

cooling and additional pressure losses in the

suction and hot gas lines

The total equivalent line length definition

includes the height of vertical rise pressure

drop through elbows and accessories and

horizontal line length so elbows

accessories and vertical rise must be

considered when determining horizontal

length available from the total equivalent

line length

The figure below is presented in terms of the

liquid line but it assumes that the suction

line length is similar as these lines are

commonly routed together to minimize the

space and cost required for split system

installation

Before using this table read the When to Use Predetermined Line Sizes section Do not assume that these line sizes are appropriate for every case Consult ASHRAE Handbook ndash Refrigeration for generally accepted system piping practices The AAON Refrigerant Piping Calculator in Ecat32 can be used for job specific line sizing

CAUTION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 25: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

25

Table 2 - Predetermined Line sizes for CB units with two step compressors and R-410A

Model Connection Sizes Predetermined Line Size

Liquid Suction Hot Gas Liquid Suction HGBP HGRH

CB-024 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 38rdquo

CB-036 38rdquo 34rdquo 38rdquo 38rdquo 34rdquo 38rdquo 12rdquo

CB-048 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

CB-060 38rdquo 78rdquo 12rdquo 12rdquo 78rdquo 12rdquo 12rdquo

Hot Gas Bypass line

Hot Gas Reheat line

Figure 6 - Riser height versus total equivalent line length

Note Figure 6 is for R-410A split system applications with two step compressor CB-024

through CB-060 units The region of acceptable riser height is the lighter area Select the

corresponding predetermined line size from Table 2 above

Total Equivalent Line Length in this figure is limited to 160 equivalent feet

CAUTION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 26: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

26

Startup (See back of the manual for startup form)

Before startup of the condenser or

condensing unit make sure that the

following items have been checked

1 Verify that electrical power is available

to the unit

2 Verify that any remote stopstart device

connected to the unit controller is

requesting the unit to start

Confirm the compressor is operating within

tolerance

While performing the check use the startup

form to record observations of amps and

refrigerant pressures

When all is running properly place the

controller in the Run mode and observe the

system until it reaches a steady state of

operation

Compressors

All compressors are equipped with

crankcase heaters which should be

energized at least 24 hours prior to cooling

operation of the compressor

3-PHASE ROTATION

Rotation must be checked on all MOTORS AND COMPRESSORS of three phase units Condenser fan motors should all be checked by a qualified service technician at startup and any wiring alteration should only be made at the unit power connection

CAUTION

COMPRESSOR ROTATION

Scroll compressors are directional and will be damaged by operation in the wrong direction Low pressure switches on compressors have been disconnected after factory testing Rotation should be checked by a qualified service technician at startup using suction and discharge pressure gauges and any wiring alteration should only be made at the unit power connection

CAUTION

ELECTRIC SHOCK

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

QUALIFIED INSTALLER

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Startup and service must be performed by a Factory Trained Service Technician

WARNING

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 27: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

27

Charging Refrigerant amp Adjusting

Refrigerant Charge

The unit comes with full charge based on a

25 foot line set Charging a system in the

field must be based on determination of

liquid sub-cooling and evaporator superheat

On a system with a TXV liquid sub-cooling

is more representative of the charge than

evaporator superheat but both measurements

must be taken

Before Charging

Refer to the Unit Nameplate to determine

which refrigerant must be used to charge the

system

Unit being charged must be at or near full

load conditions before adjusting the charge

Units equipped with hot gas bypass must

have the hot gas bypass valve closed to get

the proper charge

Units equipped with hot gas reheat must be

charged with the hot gas valves closed while

the unit is in cooling mode After charging

unit should be operated in reheat

(dehumidification) mode to check for

correct operation

Units equipped with heat pump options

should be charged in heating mode to get the

proper charge After charging unit should

be operated in cooling mode to check for

correct charge Charge may need to be

adjusted for cooling mode If adjustments

are made in the cooling mode heating mode

must be rerun to verify proper operation

After adding or removing charge the system

must be allowed to stabilize typically 10-15

minutes before making any other

adjustments

The type of unit and options determine the

ranges for liquid sub-cooling and evaporator

superheat Refer to the table of acceptable

refrigerant circuit values when determining

the proper sub-cooling

Checking Liquid Sub-cooling

Measure the temperature of the liquid line as

it leaves the condenser coil

Read the gauge pressure reading of the

liquid line close to the point where the

temperature was taken You must use liquid

line pressure as it will vary from discharge

pressure due to condenser coil pressure

drop

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart or Table 5 below

CLEAN AIR ACT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCrsquos and HCFCrsquos) as of July 1 1992 Approved methods of recovery recycling or reclaiming must be followed Fines andor incarceration may be levied for non-compliance

CAUTION

COMPRESSOR LUBRICANT

Polyolester (POE) and Polyvinylether (PVE) oils are two types of lubricants used in hydrofluorocarbon (HFC) refrigeration systems Refer to the compressor label for the proper compressor lubricant type

CAUTION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 28: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

28

Subtract the measured liquid line

temperature from the saturated temperature

to determine the liquid sub-cooling

Compare calculated sub-cooling to Table 3

below for the appropriate unit type and

options

Checking Evaporator Superheat

Measure the temperature of the suction line

close to the compressor

Read gauge pressure at the suction line close

to the compressor

Convert the pressure obtained to a saturated

temperature using the appropriate refrigerant

temperature-pressure chart

Subtract the saturated temperature from the

measured suction line temperature to

determine the evaporator superheat

Compare calculated superheat to Table 3

below for the appropriate unit type and

options

Table 3 - Acceptable Refrigeration Circuit

Values

Air-Cooled CondAir-Source Heat Pump

Sub-Cooling

12-18degF 2-4degF (HP)

Sub-Cooling with

Hot Gas Reheat 15-22degF 2-6degF (HP)

Superheat

8-15degF

In cooling mode operation

Sub-cooling must be increased by 2degF per

20 feet of vertical liquid line rise for R-410A

Superheat will increase with long

suction line runs

Adjusting Sub-cooling and Superheat

Temperatures

The system is overcharged if the sub-cooling

temperature is too high and the evaporator is

fully loaded (low loads on the evaporator

result in increased sub-cooling) and the

evaporator superheat is within the

temperature range as shown in Table 3 (high

superheat results in increased sub-cooling)

Correct an overcharged system by reducing

the amount of refrigerant in the system to

lower the sub-cooling

The system is undercharged if the superheat

is too high and the sub-cooling is too low

Correct an undercharged system by adding

refrigerant to the system to reduce superheat

and raise sub-cooling

If the sub-cooling is correct and the

superheat is too high the TXV may need

adjustment to correct the superheat

Special Low Ambient Option Charging

Instructions

For units equipped with low ambient control

(LAC) refrigerant flood back option being

charged when the ambient temperature is

warm

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

must be added Add approximately 80 of

the receiver tank volume to the charge to

help fill the receiver tank The additional

charge is required for the system when

running in cold ambient conditions

DO NOT OVERCHARGE Refrigerant overcharging leads to excess refrigerant in the condenser coils resulting in elevated compressor discharge pressure

CAUTION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 29: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

29

For units equipped with low ambient

refrigerant flood back option being charged

when the ambient temperature is cold

Once enough charge has been added to get

the evaporator superheat and sub-cooling

values to the correct setting more charge

may need to be added If the ambient

temperature is 0degF no more charge is

required If the ambient temperature is

around 40degF add approximately 40 of the

receiver tank volume

The unit will have to be checked for proper

operation once the ambient temperature is

above 80degF

Air Flow

Table 4 - Performance Testing Air Flow Setpoints

Model Cooling Stage 2

(cfm)

Cooling Stage 1

(cfm)

Heating Stage 2

(cfm)

Heating Stage 1

(cfm)

CB-B-024---1 885 66375 885 7965

CB-B-036---1 1250 9375 1250 1125

CB-B-048---1 1500 1125 1500 1350

CB-B-060---1 1545 115875 1545 13905

Before completing startup and leaving the unit a complete operating cycle should be observed to verify that all components are functioning properly

CAUTION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 30: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

30

Table 5 - R-410A Refrigerant Temperature-Pressure Chart

degF PSIG degF PSIG degF PSIG degF PSIG degF PSIG

20 783 47 1347 74 2137 101 3210 128 4632

21 800 48 1372 75 2171 102 3256 129 4693

22 818 49 1397 76 2206 103 3302 130 4754

23 836 50 1422 77 2241 104 3349 131 4816

24 854 51 1448 78 2277 105 3396 132 4878

25 872 52 1474 79 2313 106 3444 133 4941

26 891 53 1501 80 2349 107 3493 134 5005

27 910 54 1528 81 2386 108 3542 135 5069

28 929 55 1555 82 2423 109 3591 136 5134

29 949 56 1582 83 2460 110 3641 137 5200

30 968 57 1610 84 2498 111 3691 138 5266

31 988 58 1638 85 2537 112 3742 139 5333

32 1009 59 1667 86 2575 113 3794 140 5401

33 1029 60 1696 87 2614 114 3846 141 5470

34 1050 61 1725 88 2654 115 3899 142 5539

35 1071 62 1754 89 2694 116 3952 143 5609

36 1092 63 1784 90 2735 117 4005 144 5679

37 1114 64 1815 91 2776 118 4059 145 5751

38 1136 65 1845 92 2817 119 4114 146 5823

39 1158 66 1876 93 2859 120 4169 147 5896

40 1181 67 1907 94 2901 121 4225 148 5969

41 1203 68 1939 95 2944 122 4282 149 6044

42 1227 69 1971 96 2987 123 4339 150 6119

43 1250 70 2004 97 3030 124 4396

44 1274 71 2036 98 3075 125 4454

45 1298 72 2070 99 3119 126 4513

46 1322 73 2103 100 3164 127 4573

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 31: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

31

Operation

Unit operations should be controlled with

thermostat or unit controller never at the

main power supply except for emergency

servicing or complete shutdown of the unit

Thermostat Operation

Heating

Thermostat system switch - Heat

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Cooling

Thermostat system switch - Cool

Thermostat fan switch - Auto or On

Thermostat temperature set to desired point

Air Circulation

Thermostat system switch - Off

Thermostat fan switch - Auto or On

No change of the thermostat temperature

With these settings the air handlerrsquos supply

fan will run continuously but the supply air

will not be heated cooled or dehumidified

System Off

Thermostat system switch - Off

Thermostat fan switch - Auto

No change of the thermostat temperature

With these settings the system is shut down

with the exception of the control system

power (24 VAC) and the crankcase heaters

(about 60 wattscompressor)

Night and Weekend Unoccupied Operation

To reduce the operating time of the unit

when the space is unoccupied such as nights

and weekends it is recommended that the

temperature setting be raised about 5degF

while unoccupied during the cooling season

and lowered about 10degF during the heating

season

Compressor

The compressors must be off for a minimum

of 5 minutes and on for a minimum of 5

minutes Short cycling of the compressors

can causes undue stress and wear

Variable Capacity Compressor

Controller

Units with variable capacity scroll

compressors may include variable capacity

compressor controller The following is an

explanation of the terminals and

troubleshooting of the alert flash codes on

the controller For more information on the

compressor controller see Emerson Climate

Bulletin AE8-1328

COMPRESSOR CYCLING

5 MINUTE MINIMUM OFF TIME To prevent motor overheating compressors must cycle off for a minimum of 5 minutes

5 MINUTE MINIMUM ON TIME To maintain the proper oil level compressors must cycle on for a minimum of 5 minutes The cycle rate must not exceed 6 starts per hour

WARNING

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 32: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

32

Figure 7 - Variable Capacity Compressor

Controller

Low Voltage Terminals

24COM Module Common

24VAC Module Power

C1 amp C2 Demand Input

P1 Pressure Common

P2 Pressure Input

P3 Pressure Power 5VDC

P4 Pressure Shield

P5 amp P6 Pressure Output

T1 amp T2 Discharge Temperature Sensor

High Voltage Terminals

A1 amp A2 Alarm Relay Out

M1 amp M2 Contactor

L1 Control Voltage N

L2 Control Voltage L

U1 amp U2 Digital Unloader Solenoid

V1 amp V2 Vapor Injection Solenoid

The compressor controller modulates the

compressor unloader solenoid in an onoff

pattern according the capacity demand

signal of the system The following table

shows the linear relationship between the

demand signal and compressor capacity

modulation The compressor controller also

protects the compressor against high

discharge temperature Refer to Table 7 for

the relationship between thermistor

temperature readings and resistance values

Table 6 - Demand Signal vs Compressor Capacity Modulation

Demand

Signal (VDC) Loaded Unloaded Time Loaded

Time

Unloaded

Compressor

Capacity

100 Off Off Off Off 0

144 10 90 15 sec 135 sec 10

300 50 50 75 sec 75 sec 50

420 80 20 12 sec 3 sec 80

500 100 0 15 sec 0 sec 100

To avoid damaging the compressor controller DO NOT connect wires to terminals C3 C4 T3 T4 T5 or T6

WARNING

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 33: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

33

Figure 8 - Compressor Controller Flash Code Details

Table 7 - Thermistor Temperature vs Resistance Values

degC degF kΩ degC degF kΩ

-40 -40 288960 75 167 1273

-35 -31 208722 80 176 1079

-30 -22 152220 85 185 920

-25 -13 112144 90 194 787

-20 -4 83472 95 203 677

-15 5 62728 100 212 585

-10 14 47574 105 221 509

-5 23 36399 110 230 445

0 32 28082 115 239 387

5 41 21841 120 248 335

10 50 17117 125 257 292

15 59 13514 130 266 258

20 68 10744 135 275 228

25 77 8600 140 284 202

30 86 6928 145 293 180

35 95 5616 150 302 159

40 104 4581 155 311 139

45 113 3758 160 320 125

50 122 3099 165 329 112

55 131 2568 170 338 101

60 140 2140 175 347 092

65 149 1791 180 356 083

70 158 1507

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 34: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

34

Low Ambient Operation

During low ambient temperatures the vapor

refrigerant will migrate to the cold part of

the system (condenser) and condense into

liquid All CB Series compressors are

provided with factory installed crankcase

heaters to help prevent liquid refrigerant

from slugging the compressors during

startup in low ambient conditions The

condenser or condensing unit must have

continuous power 24 hours prior to startup

This ensures the compressor will receive

sufficient refrigerant vapor at startup

Standard units can operate down to 55degF

ambient temperature

AAON head pressure control units can

operate down to 35degF ambient temperature

Two different head pressure control options

available are adjustable fan cycling or ECM

condenser fan See detailed information

following

The AAON low ambient (condenser flood-

back) system is used to operate a refrigerant

system down to 0degF outside air temperature

See detailed information below

Fan Cycling Low Ambient

Adjustable fan cycling is a low ambient

head pressure control option that cycles the

condenser fans to maintain refrigerant

circuit head pressures at acceptable levels

during cooling operation The head pressure

set point (100-470 psi) and pressure

differential (35-200 psi) can be field

adjusted using a flathead screwdriver For

example if the head pressure is set to

300psi and the differential is set to 100psi

then fans will cut in at 300psi and cut out at

200psi Fan cycling and variable speed

condenser fan head pressure control options

allow mechanical cooling with ambient

temperatures down to 35degF

Figure 9 - Adjustable Fan Cycling Switch

Variable Speed Low Ambient

Variable speed condenser fan head pressure

control is a low ambient head pressure

control option that sends to an electronically

commutated motor a variable signal in

relation to the refrigerant circuit head

pressure of the system The motor either

speeds up or slows down air flow

accordingly in order to maintain constant

head pressure Fan cycling and variable

speed condenser fan head pressure control

options allow mechanical cooling with

ambient temperatures down to 35degF

Flooded Condenser Low Ambient

Flooded Condenser low ambient control

maintains normal head pressure during

periods of low ambient When the ambient

temperature drops the condensing

temperature and therefore pressure drops

Without ambient control the system would

shut down on low discharge pressure The

flooded condenser method of low ambient

control fills the condenser with liquid

refrigerant decreasing the heat transfer

capacity of the coil which allows the coil to

operate at an acceptable discharge pressure

The condenser coil will not be flooded

during summer ambient temperatures so a

receiver is included to store the additional

liquid refrigerant required to flood the

condenser in low ambient

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 35: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

35

The low ambient system maintains normal

head pressure during periods of low ambient

by restricting liquid flow from the condenser

to the receiver and at the same time

bypassing hot gas around the condenser to

the inlet of the receiver This reduces liquid

refrigerant flow from the condenser

reducing its effective surface area which in

turn increases the condensing pressure At

the same time the bypassed hot gas raises

liquid pressure in the receiver allowing the

system to operate properly CF Series

condensers and condensing units use an

LAC valve for low ambient operation

LAC Valve

The Low Ambient Control (LAC) valve is a

non-adjustable three way valve that

modulates to maintain receiver pressure As

the receiver pressure drops below the valve

setting (295 psig for R-410A) the valve

modulates to bypass discharge gas around

the condenser The discharge gas warms the

liquid in the receiver and raises the pressure

to the valve setting The following

schematic shows an example system using

the LAC valve

Figure 10 - Piping Schematic of Example System using the LAC Valve

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 36: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

36

Condenser Flooding

In order to maintain head pressure in the

refrigeration system liquid refrigerant is

kept in the condenser to reduce condenser

surface The following chart shows the

percentage that a condenser must be flooded

in order to function properly at the given

ambient temperature

During higher ambient temperatures the

entire condenser is required to condense

refrigerant During these higher ambient

temperatures a receiver tank is used to

contain the refrigerant that was required to

flood the condenser during low ambient

operation The receiver is factory-sized to

contain all of the flooded volume Without a

receiver there would be high head pressures

during higher ambient conditions

Table 8 - Condenser Flooding PERCENTAGE OF CONDENSER TO BE

FLOODED

Ambient

Temperature

(degF)

Evaporating Temperature (degF)

0deg 10deg 20deg 30deg 35deg 40deg 45deg 50deg

70deg 40 24 0 0 0 0 0 0

0deg 60 47 33 17 26 20 10 4

50deg 70 60 50 38 45 40 33 28

40deg 76 68 60 50 56 52 46 42

30deg 80 73 66 59 64 60 55 51

20deg 86 77 72 65 69 66 62 59

0deg 87 83 78 73 76 73 70 68

Compressor Lockouts

Some units include adjustable compressor

lockouts The compressor lockout in the

picture below can be set to any temperature

between -10degF and 70degF The ambient

temperature sensor hangs right outside the

unit with a cover

Figure 11 - Adjustable compressor lockout

Heat pump units include a non-adjustable

compressor lockout for the cooling mode set

to 55degF and an adjustable compressor

lockout for the heating mode that can be set

between 20degF to 95degF If a heat pump is

selected with the compressor lockout

feature the adjustable compressor lockout

will change to the -10degF to 70degF range

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 37: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

37

Maintenance (See back of the manual for maintenance

log)

At least once each year a qualified service

technician should check out the unit This

includes reading and recording suction

pressures and checking for normal sub-

cooling and superheat

Only trained and qualified service

technicians experienced in both condensing

units and air conditioning are permitted to

service the CB Series units to keep

warranties in effect

Coils

The condenser coils should be inspected

yearly to ensure unrestricted airflow If the

coils contain a large amount of airborne dust

or other material they should be cleaned

Care must be taken to prevent bending of the

aluminum fins on the coils

Before attempting to clean the coils set

thermostat to the OFF position turn the

electrical power to the unit to the OFF

position at the disconnect switch The

condenser coil can be cleaned by washing

from the inside out with water and a coil

cleaner If coil is extremely dirty with

clogged fins a service professional

specializing in coil cleaning should be

called

E-Coated Coil Cleaning

Documented routine cleaning of e-coated

coils is required to maintain coating

warranty coverage

Surface loaded fibers or dirt should be

removed prior to water rinse to prevent

restriction of airflow If unable to back wash

the side of the coil opposite of the coils

entering air side then surface loaded fibers

or dirt should be removed with a vacuum

cleaner If a vacuum cleaner is not available

a soft non-metallic bristle brush may be

used In either case the tool should be

applied in the direction of the fins Coil

surfaces can be easily damaged (fin edges

bent over) if the tool is applied across the

fins

Use of a water stream such as a garden

hose against a surface loaded coil will drive

the fibers and dirt into the coil This will

make cleaning efforts more difficult Surface

loaded fibers must be completely removed

prior to using low velocity clean water rinse

A monthly clean water rinse is

recommended for coils that are applied in

coastal or industrial environments to help to

remove chlorides dirt and debris It is very

important when rinsing that water

temperature is less than 130degF and pressure

is than 100 psig to avoid damaging the fin

edges An elevated water temperature (not to

exceed 130degF) will reduce surface tension

increasing the ability to remove chlorides

and dirt

Improper installation adjustment alteration service or maintenance can cause property damage personal injury or loss of life Installation and service must be performed by a trained qualified installer

WARNING

Electric shock hazard Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts

WARNING

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 38: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

38

Quarterly cleaning is essential to extend

the life of an e-coated coil and is required

to maintain coating warranty coverage Coil cleaning shall be part of the unitrsquos

regularly scheduled maintenance

procedures Failure to clean an e-coated coil

will void the warranty and may result in

reduced efficiency and durability

For routine quarterly cleaning first clean the

coil with the below approved coil

cleaner After cleaning the coils with the

approved cleaning agent use the approved

chloride remover to remove soluble salts and

revitalize the unit

Recommended Coil Cleaner The following cleaning agent assuming it is

used in accordance with the manufacturerrsquos

directions on the container for proper mixing

and cleaning has been approved for use on

e-coated coils to remove mold mildew

dust soot greasy residue lint and other

particulate

Enviro-Coil Concentrate Part Number H-

EC01

Recommended Chloride Remover CHLORRID DTStrade should be used to

remove soluble salts from the e-coated coil

but the directions must be followed closely

This product is not intended for use as a

degreaser Any grease or oil film should first

be removed with the approved cleaning

agent

Remove Barrier - Soluble salts adhere

themselves to the substrate For the effective

use of this product the product must be able

to come in contact with the salts These salts

may be beneath any soils grease or dirt

therefore these barriers must be removed

prior to application of this product As in all

surface preparation the best work yields the

best results

Apply CHLORRID DTS - Apply directly

onto the substrate Sufficient product must

be applied uniformly across the substrate to

thoroughly wet out surface with no areas

missed This may be accomplished by use of

a pump-up sprayer or conventional spray

gun The method does not matter as long as

the entire area to be cleaned is wetted After

the substrate has been thoroughly wetted

the salts will be soluble and is now only

necessary to rinse them off

Rinse - It is highly recommended that a hose

be used as a pressure washer will damage

the fins The water to be used for the rinse is

recommended to be of potable quality

though a lesser quality of water may be used

if a small amount of CHLORRID DTS is

added Check with CHLORRID

High velocity water from a pressure washer or compressed air should only be used at a very low pressure to prevent fin andor coil damages The force of the water or air jet may bend the fin edges and increase airside pressure drop Reduced unit performance or nuisance unit shutdowns may occur

CAUTION

Harsh chemicals household bleach or acid cleaners should not be used to clean outdoor or indoor e-coated coils These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating If there is dirt below the surface of the coil use the recommended coil cleaners

CAUTION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 39: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

39

International Inc for recommendations on

lesser quality rinse water

DX Cooling

Set unit controls to cooling mode of

operation with supply fans on Check

compressor operation rotation amperage

and voltage to the unit nameplate (check the

amperage on the load side of the compressor

contactor)

The scroll compressors are fully hermetic

and require no maintenance except for

keeping the shell clean

Refrigerant circuit includes factory provided

and field installed line filter drier The unit

does not include a liquid line solenoid valve

This must be field furnished and installed if

required by job conditions

Condenser Fan Motor

All original motors and bearings are

furnished with factory lubrication They

require no lubrication

The electrically commutated condenser fan

motor (ECM) is factory preprogrammed and

requires no maintenance

Replacement Parts

Parts for AAON equipment may be obtained

from your local AAON representative

Reference the unit serial number and part

number when ordering parts

AAON ndash Longview

Warranty Service and Parts Department

203 Gum Springs Rd

Longview TX 75602

Ph 903-236-4403

Fax 903-247-9219

wwwaaoncom

Note Before calling technician should have

model and serial number of the unit

available for the service department to help

answer questions regarding the unit

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 40: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

40

Refrigerant Piping Diagrams

Figure 12ndash AC only piping AHU above CU

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 41: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

41

Figure 13 ndash AC only piping AHU below CU

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 42: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

42

Figure 14 ndash Modulating hot gas reheat piping AHU above CU

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 43: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

43

Figure 15 ndash Modulating hot gas reheat piping AHU below CU

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 44: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

44

Figure 16 ndash Hot gas bypass piping AHU above CU

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 45: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

45

Figure 17 ndash Hot gas bypass piping AHU below CU

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 46: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

46

Figure 18 ndash Modulating hot gas reheat with hot gas bypass piping AHU above CU

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 47: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

47

Figure 19 ndash Modulating hot gas reheat with hot gas bypass piping AHU below CU

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 48: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

48

Figure 20 ndash Heat pump piping AHU above CU

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 49: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

49

Figure 21 ndash Heat pump piping AHU below CU

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 50: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

50

Figure 22 ndash Heat pump with modulating hot gas reheat piping AHU above CU

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 51: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

51

Figure 23 ndash Heat pump with modulating hot gas reheat AHU below CU

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 52: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

CB Series Startup Form

Date______________

Job Name_____________________________________________________________________

Address______________________________________________________________________

Model Number_________________________________________________________________

______________________________________________________________________________

Serial Number_____________________________________________ Tag_______________

Startup Contractor______________________________________________________________

Address__________________________________________________

_________________________________________________________ Phone_____________

Pre Startup Checklist

Installing contractor should verify the following items

1 Is there any visible shipping damage Yes No

2 Is the unit level Yes No

3 Are the unit clearances adequate for service and operation Yes No

4 Do all access doors open freely and are the handles operational Yes No

5 Have all shipping braces been removed Yes No

6 Have all electrical connections been tested for tightness Yes No

7 Does the electrical service correspond to the unit nameplate Yes No

8 On 208230V units has transformer tap been checked Yes No

9 Has overcurrent protection been installed to match the unit nameplate

requirement Yes No

10 Have all set screws on the fans been tightened Yes No

11 Do all fans and pumps rotate freely Yes No

12 Is all copper tubing isolated so that it does not rub Yes No

Ambient Temperature

Ambient Dry Bulb Temperature ________degF Ambient Wet Bulb Temperature ________degF

Refrigeration System 1 - Cooling Mode

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 53: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

Refrigeration System 1 - Heating Mode (Heat Pump Only)

Pressure Saturated

Temperature

Line

Temperature Sub-cooling Superheat

Discharge

Suction

Liquid

Air-Cooled Condenser Fan

Alignment_____

Check Rotation_____

Nameplate Amps________

Number hp L1 L2 L3

1

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 54: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

Maintenance Log

This log must be kept with the unit It is the responsibility of the owner andor

maintenanceservice contractor to document any service repair or adjustments AAON Service

and Warranty Departments are available to advise and provide phone help for proper operation

and replacement parts The responsibility for proper start-up maintenance and servicing of the

equipment falls to the owner and qualified licensed technician

Entry Date Action Taken NameTel

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 55: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

Literature Change History

November 2009

Update of manual formatting to match with other IOMs and adding variable capacity scroll

compressor information

April 2012

Added oil drip note below piping diagrams Updated the Startup Form

May 2012

Updated the Table of Contents

March 2013

Update of the manual revising Table S1 - Sub-Cooling and Superheat adding Table S2 -

Performance Testing Air Flow Setpoints adding information about compressor cycling

June 2013

Updated piping diagrams to show internal modulating hot gas reheat and hot gas bypass valves

New part number assigned

July 2014 Updated service clearance drawing

February 2015

Updated Feature 5 options to reflect standard exterior corrosion protection

July 2015

Updated Replacement Parts instructions Added Features and Options section

August 2016

Added Storage information Added guidelines for variable capacity compressors in the line

sizing section Added double riser schematics and discussion for heat pump operation Added a

section about oil level under the refrigerant line sizing section Added a section on compressor

lockouts Included heat pump charging guidelines in the Acceptable Refrigeration Circuit

Values Table Added Special Low Ambient Option Charging Instructions Changed e-coated

coil cleaning to100 psi water pressure

December 2016

Fixed a reference error

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK

Page 56: Condensing Units - AAON · CB - B - 060 - 3 - B - 1 : B D 0 0 D A 0 10 CB Base Model and Features DescriptionBASE MODEL FEATURE 2: REFRIGERATION SERIES AND GENERATION CB REVISION

AAON

203 Gum Springs Rd

Longview TX 75602-1721

Phone 903-236-4403

Fax 903-236-4463

wwwaaoncom

CB Series

Installation Operation amp

Maintenance

R57611 Rev A 161221

(ACP J00187)

It is the intent of AAON to provide accurate and current product information However in the

interest of product improvement AAON reserves the right to change pricing specifications

andor design of its product without notice obligation or liability

Copyright copy AAON all rights reserved throughout the world

AAONreg and AAONAIRE

reg are registered trademarks of AAON Inc Tulsa OK