MicroTech II™ Applied Rooftop Unit Controllermcquayservice.com/bizlit/literature/lit_aa_rah/IMOM/OM...McQuay OM 138-3 5 Getting Started The MicroTech II Applied Rooftop Unit Controller

© 2006 McQuay International

MicroTech II™Applied Rooftop Unit Controller

Space Comfort Control (SCC)

• Used with McQuay models: RPS, RFS, RCS, RPR, RFR, RDT, RPE, RDE, RCE, RDS, RAR, and RAH

Operation Manual OM 138-3

Group: Applied Systems

Part Number: OM138

Date: September 2006

Discharge CoolingDisch Air= 55.0°FClg Capacity= 50%Eff Clg Spt= 55°F

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Using the Keypad/Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Menu Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Display Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Password Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Keypad Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Keypad/Display Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Keypad/Display Menu Reference . . . . . . . . . . . . . . . . . . . . . . . . . 12System Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Airflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Humidity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Schedules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Setup/Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Active Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Previous Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43Remote Keypad Display Option. . . . . . . . . . . . . . . . . . . . . . . 44

Operator’s Guide . . . . . . . . . . . . . . . . . . . . . . . . . . 45Determining Unit Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

UnitStatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Clg Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Htg Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Clg Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Htg Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Auto/Manual Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Ctrl Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Appl Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Occupancy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Occ Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48OccSrc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49Tenant Override. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Emergency Override . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51Setting Controller Date and Time . . . . . . . . . . . . . . . . . . . . . 51Internal Daily Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51Holiday Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52One Event Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Optimal Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52External Time Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . 53Network Time Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Alarm Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53About Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53Remote Alarm Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55Local Alarm Indication (Keypad/Display) . . . . . . . . . . . . . . . . 55Remote Alarm Clearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56Configuring Remote Alarm Output. . . . . . . . . . . . . . . . . . . . . 57Setting Alarm Limits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Unit Configuration/Service Parameters . . . . . . . . . . . . . . . . . . . . . 58Calibrate Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58Zone (Space) Temperature Sensor . . . . . . . . . . . . . . . . . . . 59Miscellaneous Service Parameters . . . . . . . . . . . . . . . . . . . . 59Control Timer Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60Manual Output Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Description of Operation . . . . . . . . . . . . . . . . . . . . 63Operating States and Sequences . . . . . . . . . . . . . . . . . . . . . . . . . 63

About Operating States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63Operating State Descriptions. . . . . . . . . . . . . . . . . . . . . . . . . 63Operating State Sequence Chart. . . . . . . . . . . . . . . . . . . . . . 66

Startup Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66Before Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66Fan Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Heat/Cool Changeover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

0-30% Outdoor Air Damper Control. . . . . . . . . . . . . . . . . . . . . . . . 69Minimum Ventilation Control . . . . . . . . . . . . . . . . . . . . . . . . . 69

100% Outdoor Air Damper Control. . . . . . . . . . . . . . . . . . . . . . . . . 70Economizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70Economizer Changeover Method. . . . . . . . . . . . . . . . . . . . . . 71Minimum Ventilation Control . . . . . . . . . . . . . . . . . . . . . . . . . 72

Cooling: Multistage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75Low Ambient Cooling Lockout . . . . . . . . . . . . . . . . . . . . . . . . 76Compressor Staging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76Air-Cooled Condenser Fan Control . . . . . . . . . . . . . . . . . . . . 78Evaporative Condenser Control . . . . . . . . . . . . . . . . . . . . . . . 79Circuit Pumpdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Cooling: Modulating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Heating: Multistage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83Morning Warm-up Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 84High Ambient Heating Lockout. . . . . . . . . . . . . . . . . . . . . . . . 84Discharge Air Low Limit Control . . . . . . . . . . . . . . . . . . . . . . . 84

Heating: Modulating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85Morning Warm-up Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 88High Ambient Heating Lockout. . . . . . . . . . . . . . . . . . . . . . . . 88Discharge Air Low Limit Control . . . . . . . . . . . . . . . . . . . . . . . 89

Dehumidification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89Enabling Dehumidification . . . . . . . . . . . . . . . . . . . . . . . . . . . 89Dehumidification Cooling Operation. . . . . . . . . . . . . . . . . . . . 90Dehumidification Heating Operation. . . . . . . . . . . . . . . . . . . . 90

Energy Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91Enthalpy Wheel Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91Exhaust Fan Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93Energy Recovery Bypass Damper Control. . . . . . . . . . . . . . . 94

Return Fan Capacity Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94Direct Building Static Pressure Control . . . . . . . . . . . . . . . . . 94Return Fan Direct Position Control. . . . . . . . . . . . . . . . . . . . . 94SAF/RAF Differential OA Reset . . . . . . . . . . . . . . . . . . . . . . . 95

Propeller Exhaust Fan Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95Direct Building Static Pressure Control . . . . . . . . . . . . . . . . . 95Exhaust Fan Direct Position Control

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96Unoccupied Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

Unoccupied Heating (Night Setback) . . . . . . . . . . . . . . . . . . . 96Unoccupied Cooling (Night Setup) . . . . . . . . . . . . . . . . . . . . . 97Purge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97Special Space Sensor Failure Operation . . . . . . . . . . . . . . . . 98

Alarm Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

MicroTech II DDC Features . . . . . . . . . . . . . . . . . 107Direct PID Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107Cascaded PID Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107PID Control Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

Period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108Proportional Band and Integral Time . . . . . . . . . . . . . . . . . . 108

Adjusting PID Control Parameters . . . . . . . . . . . . . . . . . . . . . . . . 109Correcting System Instability (“Hunting”) . . . . . . . . . . . . . . . 109Correcting System “Sluggishness” . . . . . . . . . . . . . . . . . . . . 109PRAC Tuning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

Software Identification and Configuration. . . . . 110Software Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

Identifying Application Code Using Unit Keypad/Display . . . 110Main Control Board (MCB) Configuration. . . . . . . . . . . . . . . . . . . 111Main Control Board (MCB) Data Archiving. . . . . . . . . . . . . . . . . . 113Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . 114

IntroductionThis manual provides information regarding the MicroTech II control system used in the McQuay RoofPak applied roof-top unit product line. It specifically describes the sequences of operation and programmable options for units with fac-tory equipped space comfort control (SCC) software. It also includes information regarding how to use the keypad/dis-play to enter and display data.For information regarding MicroTech II components, input/output configurations, field wiring options and require-ments, and service procedures, refer to IM696, MicroTech II Applied Rooftop Unit Controller. For installation and startup instructions and general information regarding a particular

rooftop unit, refer to the applicable model-specific installa-tion and maintenance manual (refer to Table 1).

Table 1: Model-Specific Rooftop Unit Installation Literature

Rooftop Unit ModelInstallation &

Maintenance Data Bulletin Number

RPS/RDT/RFS/RCS 015-075C (with Scroll Compressors) IM 738

RPS/RDT/RFS/RCS 070-135C (with Reciprocating Compressors) IM 739

RPE/RDE/RCE (Evaporative Condenser Units) IM 791

RDS & RAH IM 487-3

NOTICEThis equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with this instruction manual, may cause interference to radio communications. It has been tested and found to comply with the limits for a Class A digital device, pursuant to part 15 of the FCC rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. Operation of this equipment in a residential area is likely to cause harmful interference in which case the user is required to correct the interference at his own expense. McQuay International disclaims any liability resulting from any interference or for the correction thereof.

WARNINGElectric shock hazard. Can cause personal injury or equipment damage.

This equipment must be properly grounded. Connections and service to the MicroTech II control panel must be performed only by personnel that are knowledgeable in the operation of the equipment being controlled.

WARNINGExcessive moisture in the control panel can cause hazardous working conditions and improper equipment operation.

When servicing this equipment during rainy weather, the electrical components in the main control panel must be protected from the rain.

McQuay OM 138-3 3

CAUTIONExtreme temperature hazard. Can cause damage to system components.

The MicroTech II controller is designed to operate in ambient temperatures from -20°F to 125°F. It can be stored in ambient temperatures from -40°F to 140°F. It is designed to be stored and operated in relative humidity up to 95% (non-condensing).

CAUTIONStatic sensitive components. A static discharge while handling electronic circuit boards can cause damage to the components.

Discharge any static electrical charge by touching the bare metal inside the main control panel before per-forming any service work. Never unplug any cables, circuit board terminal blocks, relay modules, or power plugs while power is applied to the panel.

WARNING To avoid possible unit damage, Compressor pumpdown is required before removing power to the controller.

4 McQuay OM 138-3

Getting StartedThe MicroTech II Applied Rooftop Unit Controller is a self-contained device that is capable of complete, stand-alone operation. Information in the controller can be displayed and modified by using the keypad/display in the unit main con-trol panel.The following sections describe how to use the keypad/dis-play.

Using the Keypad/DisplayThe keypad/display, shown in Figure 1, is provided with all MicroTech II Applied Rooftop Unit Controllers on these units. With the keypad/display, operating conditions, system alarms, control parameters, and schedules can be monitored. After password entry, set points, parameters, and schedules can be edited.

Menu StructureThe keypad accessible information in the MicroTech II con-troller is organized in a menu structure to provide quick access. As shown in Figure 2 on page 6, this structure con-tains 1 main menu and a string of 53 sub-menus. Each sub-menu is made up of one or more menu items. The string of 53 sub-menus is divided into 8 “categories.” The main menu has eight items within it that “point” or provide a “book-mark” to the first sub-menu within the respective category. The eight categories in the main menu are “System Sum-mary”, “Airflow”, “Temperature”, “Humidity”, “Schedules”, “Setup/Service”, “Active Alarms” and “Previous Alarms.” The name of each category generally describes the basic pur-pose of the menus in the particular group. Complete infor-mation regarding the contents of each sub-menu is included in “Keypad/Display Menu Reference” on page 12.

Note: Only those menu applicable to units with an 0 or 2 in position 1 of the “Software Configuration Code” are described in this manual. Refer to OM-137 for all others.

A number of menus and menu items that appear on the unit keypad/display are conditional and may not apply to a spe-

cific unit depending on the unit software configuration. The unit software configuration is defined by a “Software Con-figuration Code” shown on a label located on the backside of the door upon which the keypad/display is mounted. The Software Configuration Code can also be display via the six menu items in the Config Code menu on the unit keypad\dis-play (refer to “Software Identification and Configuration” on page 124). The menus and menu items that are shaded in Figure 2 are conditional. A menu or menu item that is condi-tional includes a reference to the position in the “Software Configuration Code” upon which its applicability depends. For example, the Duct Pressure menu in Figure 2 includes a notation [14=1 or 2]. This notation means that the Duct Pres-sure menu (and all its menu items) applied to the specific unit only if position 14 in its “Software Configuration Code” is a 1 or a 2. Otherwise, the menu or menu item is not appli-cable to the unit and does not affect its operation.

Figure 1:Keypad/display

Discharge CoolingDisch Air= 55.0°FClg Capacity= 50%Eff Clg Spt= 55°F

McQuay OM 138-3 5

Figure 2:Keypad Accessible Menu Structure

Sub Menus

Syste

m

12

3

UnitS

tatus

= __

___

A

Clg C

apac

ity=

xxx%

Htg C

apac

ity=

xxx%

Clg S

tatus

= __

___

Htg S

tatus

= __

___

Ctrl M

ode=

Off

Appl

Mode

= He

at/Co

olVA

V Ou

tput=

____

_[14

=1 or

2]

Occu

panc

y

Occu

panc

y= __

___

Occ M

ode=

Auto

OccS

rc= __

___

Tnt O

vrd=

0 min

Emer

g Ove

rride

= No

rm

Temp

eratu

res

Contr

ol Te

mp=

xxx.x

°FDi

sch A

ir= xx

x.x°F

Retur

n Air=

xxx.x

°F[1=

0 or 1

]Sp

ace T

emp=

xxx.x

°FOA

Temp

= xx

x.x°F

Ent F

an=

xxx.x

°F[9=

2,3,4,

6,7,A

or B

]

Airflo

w Su

mmar

y

Flow

Statu

s= __

___

Disc

h Fan

= __

___

RF/E

F Fa

n= __

___

[15=0

,1,2 o

r 4]

Fan O

pera

tion=

____

_

Duct

Pres

sure

[14=1

or 2]

Duct

Pres

s= x.

xx"W

CDu

ctSP

Spt=

1.00

"WC

DSP

Db=

0.08"

WC

Disc

h Fan

Cap

= xx

x%RF

/EF

Fan C

ap=

xxx%

Bldg

Pre

ssur

e[15

=1,2

or 4]

Zone

Coo

ling

Contr

ol Te

mp=

xxx.x

°FCl

g Cap

acity

= xx

x%Ef

f Clg

Spt=

xxx.x

°FOc

c Clg

Spt=

75.0°

FCl

g Dea

dban

d= 2.

0°F

CtrlT

emp S

rc= R

eturn

Spac

e Tem

p= xx

x.x°F

Unoc

cClg

Spt=

85.0°

FUn

occC

lgDiff=

3.0°

FCl

g Stat

us=

____

_OA

TClg

Lock

= 55

°FOA

TLoc

k Diff=

1°F

Bldg

Pre

ss=

x.xx"

WC

Bldg

SP S

pt= 0.

050"

WC

BSP

Db=

0.010

"WC

RF/E

F Fa

n Cap

= xx

x%

Zone

Hea

ting

Contr

ol Te

mp=

xxx.x

°FHt

g Cap

acity

= xx

x%Ef

f Htg

Spt=

xxx.x

°FOc

c Htg

Spt=

70.0°

FHt

g Dea

dban

d= 2.

0°F

CtrlT

emp S

rc= R

eturn

Spac

e Tem

p= xx

x.x°F

Unoc

cHtg

Spt=

55.0°

FUn

occH

tgDiff=

3.0°

FHt

g Stat

us=

____

_OA

THtg

Lock

= 55

°FOA

TLoc

k Diff=

1°F

Disc

harg

e Coo

ling

Disc

h Air=

xxx.x

°FCl

g Cap

acity

= xx

x%Ef

f Clg

Spt=

xxx.x

°FDA

T Cl

g Spt=

55.0°

F[1=

1 or 3

]Cl

g Db=

2.0°

FMi

n Clg

Spt=

55.0°

FMa

x Clg

Spt=

65.0°

FCl

g Res

et= N

one

[1=1 o

r 3]

Min C

lg Sp

t@=

0[1=

1 or 3

]Ma

x Clg

Spt@

= 10

0[1=

1 or 3

]

Disc

harg

e Hea

ting

Disc

h Air=

xxx.x

°FHt

g Cap

acity

= xx

x%Ef

f Htg

Spt=

xxx.x

°FDA

T Ht

g Spt=

100.0

°F[1=

1 or 3

]Ht

g Db=

2.0°

F

Min H

tg Sp

t= 60

.0°F

Max H

tg Sp

t= 12

0.0°F

Htg R

eset=

Non

e[1=

1 or 3

]Mi

n Htg

Spt@

= 0

[1=1 o

r 3]

Max H

tg Sp

t@=

100

[1=1 o

r 3]

Min D

AT C

trl= Ye

s

OA D

ampe

rEn

ergy

Rec

over

y[19

=1 or

2]

RF/E

F Fa

n Cap

= xx

x%EF

Min

Cap=

5%En

ergy

Rec

= Yes

CANC

EL

BACK

OA D

ampe

r Pos

= xx

x%[7=

1,2,3,

4,A,B

or C

]Ef

f Min

OA P

os=

xxx%

[7=3 o

r C]

OA F

low=

xxxx

xCFM

[8>0]

OA A

mbien

t= __

___

[7=3 o

r C]

MinO

A Ty

pe=

None

[7=3 o

r C]

Desig

nFlow

= No

[8>0]

MinO

A Po

s= 10

%[1=

1,3,A

or C

]Mi

nOA

Flow=

2000

CFM

[8>0]

MinO

A @

Max S

ig= 50

%[7=

3 or C

]Mi

n Sign

al= 0%

[7=3 o

r C]

Max S

ignal=

100%

[7=3 o

r C]

MinO

ARes

etMax

= 50

%[7=

3 or C

]Ma

x Fan

Diff=

50%

[15=1

or 2]

Min F

an D

iff= 20

%[15

=1 or

2]Re

set T

Limi

t= 0°

F[7=

3 or C

]Ec

onCh

govr=

Enth

alpy

[7=3 o

r C]

Econ

Chgo

vrT=

60°F

[7=3 o

r C]

Econ

Chgo

vrDiff=

1°F

[7=3 o

r C]

Max P

urge

= 60

min

[7=3 o

r C]

OA Te

mp=

xxx.x

°F

Key

pad

Key

Def

initi

ons

Mov

e D

ispl

ay L

eft

Mov

e E

dit C

urso

r Lef

t

SAVE

ENTE

R

CANC

EL

BACK

ALAR

MAL

ARM

CLEA

R

Mov

e D

ispl

ay R

ight

Mov

e E

dit C

urso

r Rig

htM

ove

Dis

play

Up

Incr

emen

t Adj

usta

ble

Par

amet

erM

ove

Dis

play

Dow

nD

ecre

men

t Adj

usta

ble

Par

amet

er

Bac

kup

To P

revi

ous

Men

uC

ance

l Edi

ting

Com

man

dS

elec

t Men

uS

ave

Edi

ted

Par

amet

erD

ispl

ay A

ctiv

e A

larm

Cle

ar A

ctiv

e A

larm

ER D

AT=

xxx.x

°FER

Exh

T= xx

x.x°F

Sys

tem

Sum

mar

y

Airf

low

Hum

idity

Sch

edul

esS

etup

/Ser

vice

Act

ive

Ala

rms

Pre

viou

s A

larm

s

1 2 3 4 5 6 7

Tem

pera

ture

8

Mai

n M

enu

Evap

Con

dens

ing[6>

0]

VFD

Spee

d= xx

x%Su

mp Te

mp=

xxx.x

°FMi

n Fan

Spe

ed=

25%

Min S

umpT

= 75

°FMa

x Sum

pT=

85°F

Stag

e Tim

e= 10

Min

A

MinD

AT Li

mit=

55.0°

F[1=

0 or 2

]

Sump

Dum

p Spt=

35°F

Dolph

in= N

o

6 McQuay OM 138-3

Figure2: Keypad Accessible Menu Structure (Continued)

CCB1

ID=

____

_[2=

1]

Daily

Sch

edule5

6

Mon=

00:00

- 00

:00Tu

e= 00

:00 -

00:00

Wed

= 00

:00 -

00:00

Thu=

00:00

- 00

:00Fr

i= 00

:00 -

00:00

Sat=

00:00

- 00

:00Su

n= 00

:00 -

00:00

Hol=

00:00

- 00

:00

One E

vent

Sche

dule

Beg=

mmm

dd@

hh:m

mEn

d= m

mm dd

@hh

:mm

Optim

al St

art

Spac

e Tem

p= xx

x.x°F

Optim

al St

art=

No

Auto

Upda

te= Ye

sHt

g Rate

= 0.4

°F/m

inHt

g OAT

= 35

°F

2nd P

Sen

sor=

Non

e[14

=1,2

or 15

=1,2

or 4]

DF C

apCt

rl= D

uctP

res

[14=1

or 2]

Remo

te DF

Cap

= 25

%[14

=1 or

2]RF

/EF

Ctrl=

Trac

king

[15=1

,2 or

4]Re

m RF

/EF

Cap=

25%

[15=1

,2 or

4]En

g Unit

s= E

nglis

h

Pass

word

s

Timeo

ut= 15

min

Clea

r Alar

m= N

o

Oper

ating

Hou

rs

Fan=

xxxx

x hr

Mech

Coo

l= xx

xxx h

r [2>

0]Co

mp 1=

xxxx

x hr

[2=1

]Co

mp 2=

xxxx

x hr

[2=1

]Co

mp 3=

xxxx

x hr

[2=1

]Co

mp 4=

xxxx

x hr

[2=1

]

Heati

ng=

xxxx

x hr

[9>0

]Ec

ono=

xxxx

x hr [

7=3 o

r C]

Tnt O

vrd=

xxxx

x hr

Duct

Stati

c P S

etup

[14=1

or 2]

DSP

Prop

bd=

6.0"W

CDS

P Int

Time=

40 se

cDS

P Pe

riod=

10 se

c

Timer

Sett

ings

Servi

ce=

0 min

Recir

culat

e= 3

min

[1=0 o

r 1]

Low

DAT=

3 mi

nMa

x MW

U= 90

min

[1=0 o

r 1]

Tnt O

vrd=

120 m

inSt

art In

it= 18

0 sec

Post

Heat=

0 mi

n[14

=1 or

2]

Time=

hh:m

m:ss

Day=

day

Date=

dd-m

mm-yy

yy

Fan T

rack

ing[14

=1 or

2 &

15=1

or 2]

DF M

ax w

/oExh

= 10

0%

Fan B

alanc

e[14

=1 or

2 &

15=1

or 2]

Fan B

alanc

e= O

ffSe

t Max

w/o

Exh=

No

Set M

in w/

o Exh

= No

Set M

ax w

/ Exh

= No

Set M

in w/

Exh

= No

Rem

RF/E

F Ca

p= 25

%

Holid

ay S

ched

ule

Hol 1

=mmm

dd-m

mmdd

Hol 2

=mmm

dd-m

mmdd

Hol 3

=mmm

dd-m

mmdd

Hol 1

3=mm

mdd-

mmmd

dHo

l 14=

mmmd

d-mm

mdd

Hol 1

5=mm

mdd-

mmmd

dHo

l 16=

mmmd

d-mm

mdd

Htg Z

ero O

AT=

0°F

Clg R

ate=

0.4°F

/min

Clg O

AT=

85°F

Clg Z

ero O

AT=

100°

F

Unit C

onfig

urati

on

AHU

ID=

____

_

Calib

rate

Mode

= No

Spac

e Sen

sor=

Yes

EFT

Sens

or=

No

ERcv

ry= xx

xxx h

r [19

=1or

2]

Time/D

ate

RF@

DFMa

x w/oE

x=95

%DF

Min

w/oE

xh=

20%

RF@

DFMi

n w/oE

x=15

%DF

Max

w/E

xh=

100%

RF@

DFMa

x w/E

x=60

%DF

Min

w/Ex

h= 20

%RF

@DF

Min w

/Ex=

10%

BEc

onom

izer S

etup

[7=3 o

r C]

Clg P

ropb

d= 30

°FCl

g IntT

ime=

60 se

cCl

g Per

iod=

30 se

c

Comp

ress

or S

etup

[2=1 &

3<8]

Lead

Circ

uit=

#1Co

mp C

trl= C

ross

Circ

Clg M

ethod

= Ave

rage

Cond

Fan

1 Spt=

0°F

Cond

Fan

2 Spt=

55°F

Cond

Fan

3 Spt=

65°F

Cond

Fan

4 Spt=

75°F

Cond

Fan

Diff=

5°F

Stag

e Tim

e= 5

min

Desig

nFlow

Setu

p[8>

0]

Wait

Tim

e= 30

sec

Modb

and=

50%

Max S

tep=

5.0%

Dead

band

= 6.0

%LH

Lvl P

os=

xxx.x

x%RH

Lvl P

os=

xxx.x

x%

Bldg

Stat

ic P

Setup

[15=1

,2 or

4]

BSP

Prop

bd=

1.0"W

CBS

P Int

Time=

10 se

cBS

P Pe

riod=

5 se

c

Chille

d Wate

r Setu

p[2=

2 or A

]

Clg P

ropb

d= 30

°FCl

g IntT

ime=

60 se

cCl

g Per

iod=

30 se

c

Stag

e Tim

e= 5

min

A Sub Menus (Continued)

Exha

ust F

an S

etup

[15=4

]

Min E

xh F

an C

ap=

25%

Min O

A Dm

pr=

5%Mi

n DF

Cap=

10%

Min S

trt T

ime=

120 s

ecMi

n Stop

Tim

e= 12

0 sec

Feed

back

= 3 W

ireFe

edba

ck=

3 Wire

AI11

Refe

renc

e= N

o

Comp

5= xx

xxx h

r [3

=6]

Comp

6= xx

xxx h

r [3

=6]

PRAC

= No

PRAC

= No

Zone

Temp

Setu

p[1=

0 or 2

]

Clg I

ntTim

e= 70

0 sec

Perio

d= 60

sec

Clg P

ropb

d= 8.

0°F

Spt S

ource

= Ke

ypad

Htg P

ropb

d= 12

.0°F

Htg I

ntTim

e= 50

0 sec

PRAC

= No

PRAC

= Yes

4

Dehu

midif

icatio

n[1=

0 or 2

]

Dehu

m St

atus=

____

_Re

l Hum

idity=

xxx%

Dew

Point

= xx

.x°F

Dehu

m Me

thod=

None

RH S

etpoin

t= 50

%De

wPoin

t Spt=

50°F

DewP

nt Db

= 2°

FRH

Db=

2%

Confi

gura

tion C

ode

Pos #

1-4=

x.xx

xPo

s # 5-

8= x.

xxx

Pos #

9-12

= x.x

xxPo

s # 13

-16=

x.xx

xPo

s # 17

-20=

x.xx

xPo

s # 21

-22=

x.x

CCB2

ID=

____

_[2=

1, &

3<8]

EHB1

ID=

____

_[9=

2]ER

B1 ID

= __

___

[19=1

or 2]

GCB1

ID=

____

[3=8]

Dehu

mid=

xxxx

x hr [

1=0o

r2]

McQuay OM 138-3 7

Figure2: Keypad Accessible Menu Structure (Continued)

Activ

e Alar

m 1

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Manu

al Co

ntrol

Manu

al Co

ntrol=

No

Disc

harg

e Fan

= Of

fRF

/EF

Fan=

Off

[15=0

,1,2 o

r 4]

Fan O

pera

tion=

Off

Alar

m= N

orma

lOA

Dam

per=

Auto

[7>0]

Mod C

oolin

g= A

uto[2=

2 or A

]Mo

d Hea

ting=

Auto

[9=1,5

or C

]VA

V Ou

tput=

Hea

t[14

=1 or

2]Di

sch V

anes

= Auto

[14=1

]

Free

ze=

Fast

[2=2,A

or 9=

1,5 or

C]

Smok

e= F

ast

OAT

Sens

or=

Fast

[1=3]

Spac

e Sen

sor=

Fas

t[1=

2 or 3

]Re

turn S

enso

r= F

ast

[1=0 o

r 1]

Disc

h Sen

sor=

Fas

t

BEn

ergy

Rec

Setu

p[19

=1 or

2]

Min E

xhT

Diff=

2°F

Max E

xhT

Diff=

6°F

Stag

e Tim

e= 5

min

RF/E

F Va

nes=

Auto

[15=1

]Di

sch V

FD= A

uto[14

=2]

RF/E

F VF

D= A

uto[15

=2]

Alar

m Ou

t Fau

lts

Duct

Hi Li

mit=

Fas

t[14

=1 or

2]Hi

Retu

rn Te

mp=

Fast

[1=0 o

r 1]

Hi D

isch T

emp=

Fas

tLo

Disc

h Tem

p= F

ast

Fan F

ail=

Fast

OA D

mpr S

tuck=

Fas

t[1=

2 or 3

]

Free

ze=

Slow

[2=2,A

or 9=

1,5 or

C]

OAT

Sens

or=

Slow

Spac

e Sen

sor=

Slow

[1=0,1

or 3]

Retur

n Sen

sor=

Slow

[1=0 o

r 1]

Ent F

an S

ens=

Slow

[18=1

]Lo

Airfl

ow=

Slow

[9=2,3

,4,6,7

,A or

B]

Alar

m Ou

t Pro

blems

Heat

Fail=

Slow

[9=3,4

,6,A

or B

]Fa

n Retr

y= S

low[14

=2]

Hi P

ress

-Ckt1

= Sl

ow[3<

8]Hi

Pre

ss-C

kt2=

Slow

[3<8]

Lo P

ress

-Ckt1

= Sl

ow[3<

8]Lo

Pre

ss-C

kt2=

Slow

[3<8]

Fros

t-Ckt1

= Sl

ow[3<

8]Fr

ost-C

kt2=

Slow

[3<8]

Comp

#1 A

lm=

Slow

[3<8]

Comp

#2 A

lm=

Slow

[3<8]

Comp

#3 A

lm=

Slow

[3=4,5

,6 or

7]Co

mp #4

Alm

= Sl

ow[3=

5,6 or

7]

Pump

Down

-Ckt1

= Of

f[3<

8]Pu

mpDo

wn-C

kt2=

Off

[3<8]

Ckt1

Clg E

na=

Slow

[3<8]

Ckt2

Clg E

na=

Slow

[3<8]

GenC

Clg

Ena=

Slow

[3=8]

HtgB

Htg

Ena=

Slow

[9=2]

Ckt1

Comm

Fail

= Sl

ow[3<

8]Ck

t2 Co

mm F

ail=

Slow

[3<8]

Genc

Com

m Fa

il= S

low[3=

8]Ht

gB C

omm

Fail=

Slow

[9=2]

ERec

B Co

mmFa

il= S

low[19

=1 or

2]

Activ

e Alar

m 2

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Activ

e Alar

m 3

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Activ

e Alar

m 4

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Prev

ious A

larm

1

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Prev

ious A

larm

4

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Prev

ious A

larm

5

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Prev

ious A

larm

6

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Prev

ious A

larm

7

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Prev

ious A

larm

8

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

78

Sub Menus (Continued)

Min O

ff Tim

e= 20

min

Comp

#5 A

lm=

Slow

[3=6]

Comp

#6 A

lm=

Slow

[3=6]

Alar

m Lim

its

Hi D

isch A

lm=

170°

FLo

Disc

h Alm

= 40

°FHi

Retu

rn A

lm=

120°

F[1=

1 or 3

]

Heati

ng S

etup

Stag

e Tim

e= 5

min

[9=2,3

,4,6,7

,A or

B]

F&BP

Ctrl=

Ope

nValv

e[9=

1]F&

BP C

hgov

r= 37

°F[9=

1]Ht

g Pro

pbd=

20°F

[9=1,3

,4,5,A

,B or

C]

Htg I

ntTim

e= 12

0 sec

[9=1,3

,4,5,A

,B or

C]

Htg P

eriod

= 60

sec

[9=1,3

,4,5,A

,B or

C]

Feed

back

= 3 W

ire[9=

3,4,5,

A,B

or C

]

PRAC

= No

[9=1,3

,4,5,A

,B or

C]

Prev

ious A

larm

3

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Airflo

w Sw

itch=

Off

Dirty

Filte

r= O

ffDi

rty F

nlFltr=

Off

[20=1

]

Alar

m Ou

t War

nings

Dehu

m Se

tup[1=

0 or 2

]

Dehu

m Ct

rl= O

ccup

iedMi

nimum

Stag

es=

2Ma

ximum

Stag

es=

4

Sens

or Lo

c= R

eturn

DH S

tage T

ime=

10mi

n

Prev

ious A

larm

2

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Min E

xh O

n= 12

0 sec

Min E

xh O

ff= 12

0 sec

Rehe

at= U

nit H

eat O

nly

Gas A

ct Hi

gh=

2.9V

[9=3,4

,A or

B]

8 McQuay OM 138-3

Display FormatThe information stored in the MicroTech II controller menu structure can be viewed on the 4-line by 20-character LCD display. The current menu is displayed on the top line and up to three menu items are displayed on the next three lines (refer to Figure 3). The item lines contain one or more data fields that convey varying information. A blinking cursor indicates the current item. There is a “navigation” indicator on the right side of the top line while in navigation mode. A symbol indicates there are more items in the menu “above” the current display window. A symbol indicates there are more items in the menu “below” the current display window. A symbol indicates there are more items in the menu “above” and “below” the current display window.

Figure 3:LCD Display Format

Password ProtectionThe MicroTech II controller includes password protection to guard against inadvertent control parameter changes. When an attempt is made to change the value of an adjustable parameter with the keypad, the controller prompts the user to enter either the level 2 (L-2) or level 1 (L-1) password depending on the level required for that particular parameter. The L-2 password is 4545. The L-1 password is 6555.

Note: L-2 has a “higher” level of authority than L-1. The controller prompts for the password by displaying the following:

Figure 4:Password Protection

The password fields initially has values off 5555 in them. The first field is blinking. For example, to change the pass-

word to 4545 and enter the new value, the following proce-dure is used:

1. Pressing the Down Arrow (-) key one time decrements the first field (blinking) to a value of 4.

2. Pressing the Right Arrow key one time moves the blink-ing cursor to the second field.

3. Again pressing the Right Arrow key one time (the sec-ond field will not be changed in this example) moves the blinking cursor to the third field.

4. Pressing the Down Arrow (-) key one time decrements the third field (now blinking) to a value of 4.

5. Now the four fields should be 4545, the desired pass-word. Pressing the Enter/Save key enters the password.

If the correct password is entered, the display returns to the item to be changed and the changeable item field is blinking waiting to be modified.Password TimeoutOnce the password is entered, the controller allows further changes without prompting the user to enter a password until either the password timer expires or a different password level is required for the particular parameter to be changed. The password timer is adjustable from 2-60 minutes using the Timeout= parameter in the Passwords menu.Clear Alarm PasswordNormally clearing an active alarm does not require a pass-word entry. This is true if the Clear Alarm= item in the Pass-words menu is set to “None.” However, if this parameter is set to “L-1” the controller prompts the user to enter the level 1 password before an alarm can be cleared. If this parameter is set to “L-2” the controller prompts the user to enter the level 2 password before an alarm can be cleared. For details regarding alarm clearing, refer to “Keypad/Display Exer-cises” on page 10.

TemperaturesDisch Air=55.0°FReturn Air=73.5°FSpace Temp=74.5F

Navigation Indicator

Data FieldBlinking Cusor

Menu Line

Item Line

Item Line

Item Line

**Enter L-2 Password

Password= 5555

Blinking Data Field

McQuay OM 138-3 9

Keypad FunctionsThe MicroTech II controller keypad consists of 8 pressure sensitive membrane switches. Refer to Figure 1 on page 5. The following are descriptions of these keys and their functions.

Left Arrow Key: Pressing this key changes the displayed menu one menu to the left while navigating within the menu structure. It also changes the field to be edited one field to the left while edit-ing a parameter value.

Right Arrow Key: Pressing this key changes the displayed menu one menu to the right while navigating within the menu structure. It also changes the field to be edited one field to the right while editing a parameter value.

Up Arrow (+) Key: Pressing this key changes the displayed menu or menu item up one menu or menu item while navigating within the menu structure. It also increments a changeable parameter one value while editing.

Down Arrow (-) Key: Pressing this key changes the displayed menu or menu item down one menu or menu item while navigating within the menu structure. It also decrements a changeable parameter one value while editing.

Back/Cancel Key: Pressing this key while navigating within the menu structure changes the displayed menu back to the main menu. While editing a changeable parameter, pressing this key causes the edit session to be terminated and the parameter value reverts to the value it had before beginning the editing session. Pressing this key after having pressed the Alarm key to view

an active alarm causes the display to revert to the menu that was in the display prior to pressing the Alarm key. Pressing this key while at the main menu causes a manual password log off and resets the password timer.

Enter/Save Key:Pressing this key while viewing a menu on the main menu changes the displayed menu to the first menu of the menu group or category associated with that menu. Pressing this key while viewing a changeable menu item places the key-pad into “edit” mode. The first changeable field for that parameter begins blinking and the top line of the display is replaced with **Edit Mode, indicating the “edit” mode is activated. Once a parameter is changed in “edit” mode, pressing this key “saves” the new parameter value into mem-ory. When the new parameter value is saved, the changeable field or field stops blinking and the **Edit Mode message disappears from the top line of the display, indicating the keypad is no longer in “edit” mode.

Alarm Key:Pressing this key while the red LED above it on the keypad is on changes the displayed menu to the Active Alarm 1 menu.

Clear Alarm Key: Pressing this key while any of the active alarm menus are being displayed sends a clear command to clear the alarm.

Keypad/Display ExercisesThe following are three exercises that serve as a guide through some typical keypad operations. Note that often there is more than one way to perform an operation.Changing Set PointsIn this exercise, assume that the current minimum outdoor air damper position set point is 15%. Using the following procedure, the set point is changed to 10%.

1. Pressing the Back/Cancel key changes the display back to the main menu if not already there.

10 McQuay OM 138-3

2. Assuming the blinking cursor is positioned on the Sys-tem Summary menu, pressing the Down Arrow (-) key twice changes the cursor position to the Temperature menu.

3. Pressing the Enter/Save key changes the display to the Zone Cooling menu, the first menu in the Temperatures group of menus.

4. Pressing the Right Arrow key three times changes the display to the OA Damper menu. The cursor is posi-tioned on the first item within this menu which is the OA Damper Pos= item.

5. Pressing the Down Arrow (-) key six times moves the display down six items in the menu and positions the cursor on the MinOA Pos= item.

6. When the Enter/Save key is pressed and if the password timer has expired since the last time the password was entered, the controller prompts the user to enter a pass-word at this point. The procedure outlined above in “Password Protection” on page 9 must be followed to enter the password. Once the password has been suc-cessfully entered, the display enters the “edit” mode as show below.When the Enter/Save key is pressed and if a password entry is not required, the display simply enters the “edit” mode as shown below.

Note: The Menu Line has been replaced by the “**Edit Mode” indication message, the cursor has disap-peared and the date field to be edited is blinking.

7. Pressing the Down Arrow (-) key once decrements the current MinOA Pos= value by one percent. Pressing and holding the Down Arrow (-) causes the value to decre-ment rapidly.

8. When the MinOA Pos= parameter is at the desired value (10% in this example), pressing the Enter/Save key stores the new setting and terminates the edit session.

Note: The data field stops blinking when the new value is recorded and the display leaves the “edit” mode.

Clearing AlarmsIn this exercise, assume that a “fault” alarm exists. This type of alarm shuts down the unit and keeps it off until the alarm is manually cleared. If the conditions that caused the alarm have been corrected, the following procedure is used to clear a fault.

1. Pressing the Alarm key while the red LED on the key-pad is blinking (indicating an active alarm condition) changes the displayed menu to the Active Alarm 1 menu which displays the current highest priority alarm.

2. Pressing the Clear Alarm key sends a clear command to the controller. This clears the alarm and returns the unit to normal operation.

Modifying SchedulesIn this exercise, assume that a change in building occupancy requires the rooftop unit to run from 8:30 a.m. to 5:30 p.m. on Sunday. The current schedule has the unit shut down on Sunday. Using the following procedure, this schedule is changed accordingly. This procedure assumes that the pass-word has previously been entered and the password timer has not expired.

Note: The time schedule and time clock in the MicroTech II controller use “military” time. In this case 5:30 p.m. is equivalent to 17:30 in “military” time.

1. Pressing the Back/Cancel key changes the display to back to the main menu if not already there.

**Edit Mode

MinOA Pos= 15%

MinOA Type= NoneDesignFlow= No

Menu Line

Item Line Being Edited

Blinking Data Field

v

McQuay OM 138-3 11

2. Assuming the blinking cursor is positioned on the Sys-tem Summary menu, pressing the Down Arrow (-) key three times changes the cursor position to the Schedules menu.

3. Pressing the Enter/Save key changes the display to the Daily Schedule menu, the first menu in the Schedules group of menus.

4. Pressing the Down Arrow (-) key six times moves the display down six items in the menu and positions the cursor on the Sun= item.

5. When the Enter/Save key is pressed (and if a password entry is not required) the display enters the “edit” mode with the “start hour” data field blinking.

6. Pressing the Up Arrow (+) key once increments the cur-rent “start hour” value by one hour. Pressing and hold-ing the Up Arrow (+) causes the value to increment rapidly.

7. When the “start hour” is at the desired value (08 in this example), pressing the Right Arrow key moves the blinking cursor to the “start minute” field.

8. Pressing the Up Arrow (+) key once increments the cur-rent “start minute” value by one minute. Pressing and holding the Up Arrow (+) causes the value to increment rapidly.

9. When the “start minute” is at the desired value (30 in this example), pressing the Right Arrow key moves the blinking cursor to the “stop hour” field.

10. Pressing the Up Arrow (+) key once increments the cur-rent “stop hour” value by one hour. Pressing and holding the Up Arrow (+) causes the value to increment rapidly.

11. When the “stop hour” is at the desired value (17 in this example), pressing the Right Arrow key moves the blinking cursor to the “stop minute” field.

12. Pressing the Up Arrow (+) key once increments the cur-rent “stop minute” value by one minute. Pressing and holding the Up Arrow (+) causes the value to increment rapidly.

13. When the “stop minute” is at the desired value (30 in this example), pressing the Enter/Save key stores the new Sun= start/stop setting and terminates the session.

Note: The data field stops blinking when the new value is recorded and the display leaves the “edit” mode.

Keypad/Display Menu ReferenceThe following is a brief description of each menu and menu item within the rooftop MicroTech II menu structure. Tables are included which show every menu, item, and field in the menu structure of the program. These menus and items can all be displayed with the keypad/display.

Note: There are a number of instances where the same menu item appears under more that one menu.

System SummaryMenus in the System Summary category contain basic unit operating status and control set point parameters. Table 2 on page 14 lists all menus and items in the System Summary group or category. The “Range” column in the table lists all possible values for each item. The factory settings for the adjustable parameters are shown in the “Factory Default Value” column. The following are brief descriptions of the System Summary category menus and items.SystemThe System menu provides a summary of basic unit status and control items.

UnitStatus. UnitStatus= is a status only item which indi-cates the state in which the unit is currently operating. For detailed information regarding this parameter, refer to “Determining Unit Status” on page 45.

12 McQuay OM 138-3

Clg Capacity. Clg Capacity= is a status only item which indicates the percentage of the unit maximum cooling capac-ity currently operating.

Htg Capacity. Htg Capacity= is a status only item which indicates the percentage of the unit maximum heating capac-ity currently operating.

Clg Status. Clg Status= is a status only item which indi-cates whether or not cooling (economizer and/or mechani-cal) is currently allowed. If cooling is disabled, the reason is indicated. For detailed information regarding this parameter, refer to “Determining Unit Status” on page 45.

Htg Status. Htg Status= is a status only item which indi-cates whether or not heating is currently allowed. If heating is disabled, the reason is indicated. For detailed information regarding this parameter, refer to “Determining Unit Status” on page 45.

Ctrl Mode. Ctrl Mode= is an adjustable item which allows the unit to be set for manual off, cooling only, heating only, fan only or auto heating/cooling operation. For detailed information regarding this parameter, refer to “Auto/Manual Operation” on page 47.

Note: If this item is set to “Auto”, then cooling only, heat-ing only, fan only or auto heating/cooling operation is determined by a network signal as indicated by the Appl Mode= item.

Appl Mode. Appl Mode= is a network adjustable item which indicates that the unit is set for network off, cooling only, heating only, fan only or auto heating/cooling operation via a network signal. For detailed information regarding this parameter, refer to “Auto/Manual Operation” on page 47.

Note: This item has no affect on the unit operation unless the Ctrl Mode= item is set to “Auto.”

OccupancyMenus in the Occupancy menu contain status and control items that relate to unit occupied/unoccupied operation.

Occupancy. Occupancy= is a status only item which indi-cates whether the unit is currently in an occupied, unoccu-pied, or bypass mode of operation. For detailed information regarding this parameter, refer to “Determining Unit Status” on page 45.

Occ Mode. Occ Mode= is an adjustable item which allows the unit to be set for manual occupied or unoccupied opera-tion, automatic operation based on a time schedule input or manual bypass operation. For detailed information regarding this parameter, refer to “Auto/Manual Operation” on page 47.

OccSrc. OccSrc= is status only item which indicates the input source or function that is responsible for setting the Occupancy= parameter to “Occ.” For detailed information

regarding this parameter, refer to “Auto/Manual Operation” on page 47.

Tnt Ovrd. Tnt Ovrd= is an adjustable item which indicates the tenant override time remaining when the unit is operating due to override operation. For detailed information regarding this parameter, refer to “Auto/Manual Operation” on page 47.

Emerg Override . Emerg Override= is an adjustable item which provides a means off completely shutting off a unit via a network signal. If this parameter is set to “Off” the unit can not start based on a time clock or any other means. The only way the unit can be started is to change this parameter to “Norm.” For detailed information regarding this parame-ter, refer to “Auto/Manual Operation” on page 47.TemperaturesMenus in the Temperatures menu contain unit temperature status information.

Control Temp. Control Temp= is a status only item which displays the current value of the “Control Temperature.” The “Control Temperature” is defined as the temperature input selected by the CtrlTemp Src= parameter in the Zone Cool-ing or Zone Heating menu. For example, if the CtrlTemp Src= parameter is set to “Return”, then the Control Temp= parameter reads the same value as the Return Air= parame-ter. For detailed information regarding this parameter, refer to “Heat/Cool Changeover” on page 67.

Disch Air. Disch Air = is a status only item which displays the current temperature reading from the unit discharge air temperature sensor. This sensor is standard on all units.

Return Air. Return Air= is a status only item which dis-plays the current temperature reading from the unit return air temperature sensor. This sensor is standard on all units with return air.

Space Temp. Space Temp= is a status only item which dis-plays the current space (or zone) temperature reading from the optional unit space air temperature sensor input. Refer to “Zone (Space) Temperature Sensor” on page 59.

Note: If an optional space temperature sensor is not installed, the Space Sensor= item in the Unit Con-figuration menu should be set to “No” to disable the alarm function associated with an open circuit at the space temperature sensor input.

OA Temp. OA Temp= is a status only item which displays the current temperature reading from the unit mounted out-door air temperature sensor. This sensor is standard on all units.

Ent Fan. Ent Fan= is a status only item which displays the current temperature reading from the unit entering fan air temperature sensor. This sensor is standard on all units equipped with gas or electric heat.

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Table 2: System Summary Menus

Menu Name Menu Item Name Factory Default Value Field Number Range

System

UnitStatus - -

Off UnocOff ManOff NetOff SwOff AlmCalib

StartupRecirc

Fan OnlyEcono

CoolingMWU

HeatingMin DAT

UnocEconUnocClgUnocHtgMan Ctrl

Clg Capacity - - 0-100%Htg Capacity - - 0-100%

Clg Status - -

All ClgEcono

Mech ClgOff AmbOff Alm

Off NoneOff SwOff NetOff Man

Htg Status - -

Htg EnaOff AmbOff Alm


Ctrl Mode Off 1

OffAuto

Heat/CoolHeat OnlyCool OnlyFan Only

Appl Mode Heat/Cool 1

OffHeat/CoolHeat OnlyCool OnlyFan Only

14 McQuay OM 138-3

AirflowMenus in the Airflow category contain status and control set point parameters that define the airflow control setup of the unit. Table 3 on page 16 lists all menus and items in the Air-flow group or category. The “Range” column in the table lists all possible values for each item. The factory settings for the adjustable parameters are shown in the “Factory Default Value” column. The following are brief descriptions of the Airflow category menus and items.Airflow SummaryThe Airflow Summary menu contains status information related to unit airflow, static pressure and fan operation.

Flow Status. Flow Status= is a status only item that indi-cates whether or not discharge airflow is detected. Airflow status is sensed by a binary input delivered to the controller by a differential pressure switch (PC7).

Disch Fan. Disch Fan= is a status only item which indi-cates whether or not the controller is commanding the unit discharge fan on.

RF/EF Fan. RF/EF Fan= is a status only item which indi-cates whether or not the controller is commanding the unit return or exhaust on.

Fan Operation. Fan Operation= is a status only item which indicates the on/off status of the Fan Operation Output (MCB-BO3). For details regarding the Fan Operation Out-put, refer to the “Field Output Signals” section of IM 696, MicroTech Applied Rooftop Unit Controller.

Bldg PressureThe Bldg Pressure menu contains parameters for controlling building static pressure when a unit is equipped with a build-ing static pressure sensor. For detailed information regarding building static pressure control, refer to “Direct Building Static Pressure Control” on page 94 or “Exhaust Fan Con-trol” on page 93.

Bldg Press. Bldg Press= is a status only item which indi-cates the current pressure at the building static pressure sen-sor location.

BldgSP Spt. BldgSP Spt= is an adjustable item which sets the building static pressure set point used for controlling the return air or exhaust fan inlet vanes or VFD. The inlet vanes or VFD is modulated to maintain the building static pressure sensor input at this set point.

BSP Db. BSP Db= is an adjustable item which sets a dead band around the BldgSP Spt= parameter in the Bldg Static Pressure menu. No building static pressure control action is taken when the current building static pressure input is within this dead band.

RF/EF Fan Cap. RF/EF Fan Cap= is a status only item which indicates the current return or exhaust fan capacity. 0-100% inlet vane position is indicated if the unit is equipped with return or exhaust fan variable inlet vanes. 0-100% of VFD maximum speed is indicated if the unit is equipped with a return or exhaust fan VFD.

Occupancy

Occupancy - -Occ

UnoccTnt Ovrd

Occ Mode Auto 1

OccUnocc

Tnt OvrdAuto

OccSrc - -

NoneInt SchedNet SchedOcc Mode

Remote SwTnt Ovrd Time 0 min 1 0 -300 min

Emerg Override Norm 1Norm

Off

Temperatures

Control Temp - - -50 - 250.0°F Disch Air - - -20 - 275.0°FReturn Air - - -20 - 175.0°F

Space Temp - - 10 - 95.0°FOA Temp - - -50 - 140.0°FEnt Fan - - -50 - 140.0°F

Table 2: System Summary Menus (Continued)


McQuay OM 138-3 15

.

TemperatureMenus in the Temperature category contain status and con-trol set point parameters that define the temperature control setup of the unit. Table 4 on page 21 lists all menus and items in the Temperature group or category. The “Range” column in the table lists all possible values for each item. The factory settings for the adjustable parameters are shown in the “Factory Default Value” column. The following are brief descriptions of the Temperature category menus and items.Zone CoolingThe Zone Cooling menu primarily contains basic status and control parameters that relate to or affect the unit changeover into cooling operation and control of the space or zone tem-perature while in cooling operation. For detailed information regarding unit heating/cooling changeover, refer to “Heat/Cool Changeover” on page 67.

Control Temp. Control Temp= is a status only item which displays the current value of the “Control Temperature.” The “Control Temperature” is defined as the temperature input selected by the CtrlTemp Src= parameter in the Zone Cool-ing or Zone Heating menu. For example, if the CtrlTemp Src= parameter is set to “Return”, then the Control Temp= parameter reads the same value as the Return Air= parame-ter. For more information regarding this parameter, refer to“Heat/Cool Changeover” on page 67.


Eff Clg Spt. Eff Clg Spt= is a status only item which indi-cates the cooling changeover or zone cooling control set point currently in effect. When the current value of the Con-trol Temp= parameter rises above this parameter by more than half the Clg Deadband= parameter, cooling capacity is increased. When the current value of the Control Temp= parameter drops below this parameter by more than half the Clg Deadband= parameter cooling capacity is decreased. This parameter is either set by the controller to same value as the Occ Clg Spt= parameter or based on a signal from an optional space temperature sensor with set point adjustment capability. For details regarding the use of thermostat sup-plied set points, refer to “Tstat Source Set Points” on page 68.

Occ Clg Spt. Occ Clg Spt= is an adjustable item used by the controller to set the Eff Clg Spt= parameter. The Eff Clg Spt= is set to this value when it is not being set based on a signal from an optional space temperature sensor with set point adjustment capability. For details regarding the use of thermostat supplied set points, refer to “Tstat Source Set Points” on page 68.

Clg Deadband. Clg Deadband= is an adjustable item which sets a dead band around the Eff Clg Spt= parameter. For example, if the Eff Clg Spt= parameter is set to 75ºF and the Clg Deadband= parameter is set to 2ºF the dead band around the set point would be from 76.0ºF to 74.0ºF.

CtrlTemp Src. CtrlTemp Src= is an adjustable item which selects the temperature sensor input to be used for the unit heating/cooling changeover or zone cooling and heating capacity change decisions. For example, if the CtrlTemp Src= parameter is set to “Return”, then the Control Temp= parameter reads the same value as the Return Air= parame-ter. For detailed information regarding this parameter, refer to “Heat/Cool Changeover” on page 67.

Table 3: Airflow Menus


Airflow Summary

Flow Status - -Flow

NoFlow

Disch Fan - -On

Off

RF/EF Fan - -On

Off

Fan Operation - -On

Off

Bldg Pressure

Bldg Press - - -0.250 - 0.250 “WC

BldgSP Spt 0.050 “WC 1 -0.250 - 0.250 “WC

BSP Db 0.010 “WC 1 0.001-0.100 “WC

RF/EF Fan Cap - - 0 - 100%

16 McQuay OM 138-3



UnoccClg Spt. UnoccClg Spt= is an adjustable item which sets the point at which the unit starts up and provides unoccupied cooling (night setup) during unoccupied periods. For detailed information regarding unoccupied cooling oper-ation, refer to “Unoccupied Control” on page 96.

Note: An optional space temperature sensor is required for unoccupied cooling operation.

UnoccClgDiff. UnoccClgDiff= is an adjustable item which sets a differential below the UnoccClg Spt= parameter. Once activated, unoccupied cooling operation is terminated when the Space Temp= value falls below the UnoccClg Spt= set-ting by more than this differential.

Clg Status. Clg Status= is a status only item which indi-cates whether or not cooling (economizer and/or mechani-cal) is currently allowed. If cooling is disabled, the reason is indicated. For detailed information regarding this parameter, refer to “Determining Unit Status” on page 45.

OATClg Lock. OATComp Lock= is an adjustable item which sets the low outdoor air temperature mechanical cool-ing lockout point. Mechanical cooling operation is disabled when the outdoor air temperature sensor input falls below this set point.

OATLock Diff. OATLock Diff= is an adjustable item which sets a differential above the OATComp Lock= parameter. Mechanical cooling operation is re-enabled when the out-door air temperature sensor input rises above the OATComp Lock= value by more than this differential.Zone HeatingThe Zone Heating menu primarily contains basic status and control parameters that relate to or affect the unit changeover into heating operation and control of the space or zone tem-perature while in heating operation. For detailed information regarding unit heating/cooling changeover, refer to “Heat/Cool Changeover” on page 67.

Control Temp. Control Temp= is a status only item which displays the current value of the “Control Temperature.” The “Control Temperature” is defined as the temperature input selected by the CtrlTemp Src= parameter in the Zone Cool-ing or Zone Heating menu. For example, if the CtrlTemp Src= parameter is set to “Return”, then the Control Temp=

parameter reads the same value as the Return Air= parame-ter. For detailed information regarding this parameter, refer to “Heat/Cool Changeover” on page 67.


Eff Htg Spt. Eff Htg Spt= is a status only item which indi-cates the heating changeover or zone heating control set point currently in effect. When the current value of the Con-trol Temp= parameter, falls below this parameter by more than half the Htg Deadband= parameter, heating capacity is increased. When the current value of the Control Temp= parameter rises above this parameter by more than half the Htg Deadband= parameter heating capacity is decreased. This parameter is either set by the controller to same value as the Occ Htg Spt= parameter or based on a signal from an optional space temperature sensor with set point adjustment capability. For details regarding the use of thermostat sup-plied set points, refer to “Tstat Source Set Points” on page 68.

Occ HtgSpt. Occ Htg Spt= is an adjustable item used by the controller to set the Eff Htg Spt= parameter. The Eff Htg Spt= is set to this value when it is not being set based on a signal from an optional space temperature sensor with set point adjustment capability. For details regarding the use of thermostat supplied set points, refer to “Tstat Source Set Points” on page 68.

Htg Deadband. Htg Deadband= is an adjustable item which sets a dead band around the Eff Htg Spt= parameter. For example, if the Eff Htg Spt= parameter is set to 70ºF and the Htg Deadband= parameter is set to 2ºF the dead band around the set point would be from 69.0ºF to 71.0ºF.

CtrlTemp Src. CtrlTemp Src= is an adjustable item which selects the temperature sensor input to be used for the unit heating/cooling changeover or zone cooling and heating capacity change decisions. For example, if the CtrlTemp Src= parameter is set to “Return”, then the Control Temp= parameter reads the same value as the Return Air= parame-ter. For detailed information regarding this parameter, refer to “Heat/Cool Changeover” on page 67.



McQuay OM 138-3 17

UnoccHtg Spt. UnoccHtg Spt= is an adjustable item which sets the point at which the unit starts up and provides unoccupied heating (night setback) during unoccupied peri-ods. For detailed information regarding unoccupied heating operation, refer to “Unoccupied Heating (Night Setback)” on page 96.

Note: An optional space temperature sensor is required for unoccupied heating operation.

UnoccHtgDiff. UnoccHtgDiff= is an adjustable item which sets a differential above the UnoccHtg Spt= parameter. Once activated, unoccupied heating operation is terminated when the Space Temp= value rises above the UnoccHtg Spt= set-ting by more than this differential.

Htg Status. Htg Status= is a status only item which indi-cates whether or not heating is currently allowed. If heating is disabled, the reason is indicated.

OATHtg Lock. OATHtg Lock= is an adjustable item which sets the high outdoor air temperature heating lockout point. Heating operation is disabled when the outdoor air tempera-ture sensor input rises above this set point.

OATLock Diff. OATLock Diff= is an adjustable item which sets a differential below the OATHtg Lock= parameter. Heat-ing operation is re-enabled when the outdoor air temperature sensor input falls below the OATHtg Lock= value by more than this differential.Discharge CoolingThe Discharge Cooling menu contains parameters that relate to or are used to maintain the discharge temperature when the unit is changed over into cooling operation. For detailed information regarding cooling operation, refer to “Heat/Cool Changeover” on page 67, “Economizer” on page 70, “Cool-ing: Multistage” on page 75, and “Cooling: Modulating” on page 81, as applicable.

Disch Air. Disch Air = is a status only item which displays the current temperature reading from the unit discharge air temperature sensor. This sensor is standard on all units.


Eff Clg Spt. Eff Clg Spt= is a status only item which indi-cates the cooling discharge air temperature set point cur-rently in effect during the Econo operating state or during the Cooling operating state when the unit is equipped with chilled water cooling. Economizer dampers or the chilled water valve is modulated to maintain the unit discharge air temperature at this set point. This Eff Clg Spt= parameter is raised and lowered by the controller as necessary to maintain the Eff Clg Spt= in the Zone Cooling menu. For detailed information regarding economizer and chilled water cooling operation, refer to“Economizer” on page 70 or “Cooling: Modulating” on page 81.

Clg Db. Clg Db= is an adjustable item which sets a dead band around the Eff Clg Spt= parameter. For example, if the Eff Clg Spt= parameter is set to 55ºF and the Clg Db= parameter is set to 2ºF the dead band around the set point would be from 56.0ºF to 54.0ºF.

Min Clg Spt. Min Clg Spt= is an adjustable item which sets a minimum cooling discharge temperature set point used by the controller to limit the discharge air temperature while controlling the space or zone conditions. For detailed infor-mation on discharge air temperature control, refer to “Econo-mizer” on page 70, “Cooling: Multistage” on page 75 or “Cooling: Modulating” on page 81 as applicable.

Max Clg Spt. Min Clg Spt= is an adjustable item which sets a maximum cooling discharge temperature set point used by the controller to limit the discharge air temperature while controlling the space or zone conditions. For detailed information on discharge air temperature control, refer to “Economizer” on page 70, “Cooling: Multistage” on page 75 or “Cooling: Modulating” on page 81 as applicable.OA DamperThe OA Damper menu contains parameters that relate to or are used to control the unit outdoor air dampers. For detailed information regarding outdoor air damper control, refer to “0-30% Outdoor Air Damper Control” on page 69, “100% Outdoor Air Damper Control” on page 70, or “Economizer” on page 70, as applicable.

OA Damper Pos. OA Damper Pos= is a status only item which indicates the current outdoor air damper position.

Eff Min OA Pos. Eff Min OA Pos= is a status only item which indicates the minimum outdoor air minimum position set point currently in effect. Economizer dampers are con-trolled to maintain this position whenever minimum ventila-tion is required. For detailed information regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 69 (0-30% outdoor air units) or “Minimum Ventilation Control” on page 72 (economizer units) as applicable.

OA Flow. OA Flow= is a status only item which indicates the current outdoor airflow based on an optional OA airflow sensor input used when the unit is equipped the DesignFlow OA control feature.

OA Ambient. OA Ambient= is a status only item which indicates whether or not the outdoor air is suitable for free cooling. If it is, “Low” is displayed. If not, “High” is dis-played. The free cooling decision can be based on either an enthalpy switch input to the controller or on a dry bulb OA temperature set point. This decision is made via the EconCh-govr= parameter. For detailed information regarding econo-mizer changeover operation refer to “Economizer Changeover Method” on page 71.

18 McQuay OM 138-3

MinOA Type. MinOA Type= is an adjustable item used to select between a fixed damper position and one of three available methods of automatically resetting the Eff Min OA Pos= parameter.

Note: If the unit is equipped with the DesignFlow outdoor air measuring system and the DesignFlow= param-eter is set to “Yes”, the MinOA Type= parameter automatically reverts to “None”.

For detailed information regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 69 (0-30% outdoor air units) or “Minimum Ventilation Control” on page 72 (economizer units) as applicable.

DesignFlow. DesignFlow= is an adjustable item used to turn the optional DesignFlow outdoor airflow measuring reset function on and off. This is one of several available methods of automatically resetting the Eff Min OA Pos= parameter. For detailed information regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 72.

MinOA Pos. MinOA Pos= is an adjustable item used by the controller to set the Eff Min OA Pos= parameter. When the Eff Min OA Pos= parameter is not being set based on one of the possible outdoor damper position reset functions, it is set to the MinOA Pos= value. For detailed information regard-ing minimum ventilation control, refer to “Minimum Venti-lation Control” on page 69 (0-30% outdoor air units) or “Minimum Ventilation Control” on page 72 (economizer units) as applicable.

MinOA Flow. MinOA Flow= is an adjustable item used by the controller to set the Eff Min OA Pos= parameter when the unit is equipped with the optional DesignFlow OA con-trol feature. When the DesignFlow= parameter is set to “Yes”, the Eff Min OA Pos= is reset to maintain the OA Flow= value at the MinOA Flow= setting. For detailed infor-mation regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 72.

MinOA @Max Sig. MinOA @Max Sig= is an adjustable item used to set the Eff Min OA Pos= when the MinOA Type= is set to “Ext mA” or “Ext V.” When either “Ext mA” or “Ext V” is selected, the Eff Min OA Pos= is reset between the MinOA Pos= value and the MinOA @Max Sig= value as a field supplied external current or voltage signal varies between a minimum and maximum value. For detailed infor-mation regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 72.

Min Signal. Min Signal= is an adjustable item used to define the minimum value of the field supplied current or voltage signal used to adjust the Eff Min OA Pos= when the MinOA Type= is set to “Ext mA” or “Ext V.” Min Signal= is adjustable from 0-100%. When “Ext mA” is selected, 0-100% refers to 0-100% of 20mA. When “Ext V” is selected,

0-100% refers to 0-100% of 10VDC. For detailed informa-tion regarding minimum ventilation control, refer to “Mini-mum Ventilation Control” on page 72.

Max Signal. Max Signal= is an adjustable item used to define the maximum value of the field supplied current or voltage signal used to adjust the Eff Min OA Pos= when the MinOA Type= is set to “Ext mA” or “Ext V.” Max Signal= is adjustable from 0-100%. When “Ext mA” is selected, 0-100% refers to 0-100% of 20mA. When “Ext V” is selected, 0-100% refers to 0-100% of 10VDC. For detailed informa-tion regarding minimum ventilation control, refer to “Mini-mum Ventilation Control” on page 72.

MinOA ResetMax. MinOA ResetMax= is an adjustable item which sets a maximum value to which the Eff Min OA Pos= parameter can be set. When reset by any of the possi-ble methods, the Eff Min OA Pos= parameter varies between the Min OA Pos= and the MinOA ResetMax= value. For detailed information regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 72.

Max Fan Diff. Max Fan Diff= is an adjustable item which sets a differential between the discharge and return fan capacities above which the Eff Min OA Pos= parameter is reset to the MinOA ResetMax= value. As the difference between the discharge and return fan capacities varies between the Min Fan Diff= and Max Fan Diff= values, the Eff Min OA Pos= parameter varies between the MinOA Pos= and the MinOA ResetMax= value. For detailed infor-mation regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 72.

Min Fan Diff. Min Fan Diff= is an adjustable item which sets a differential between the discharge and return fan capacities above which the Eff Min OA Pos= parameter begins to be reset from the MinOA Pos= value toward the MinOA ResetMax= value. As the difference between the dis-charge and return fan capacities varies between the Min Fan Diff= and Max Fan Diff= values, the Eff Min OA Pos= parameter varies between the MinOA Pos= and the MinOA ResetMax= value. For detailed information regarding mini-mum ventilation control, refer to “Minimum Ventilation Control” on page 72.

Reset T Limit. Reset T Limit= is an adjustable item which sets a discharge air temperature low limit which overrides functions that reset the Eff Min OA Pos= parameter if the discharge air temperature gets too cold. For detailed infor-mation regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 72.

EconChgovr. EconChgovr= is an adjustable item which defines the method used to make the economizer changeover decision. For detailed information regarding economizer changeover operation refer to “Economizer Changeover Method” on page 71.

McQuay OM 138-3 19

EconChgovrT. EconChgovrT= is an adjustable item used to make the economizer changeover decision when the EconChgovr= parameter is set to “Dry Bulb.” It sets the point below or above which the outdoor air temperature enables or disables economizer operation. If the EconCh-govr= parameter is set to “Enthalpy”, this parameter has no effect on the unit operation. For detailed information regard-ing economizer changeover operation refer to “Economizer Changeover Method” on page 71.

EconChgovrDiff. EconChgovrDiff= is an adjustable item which sets a differential above the EconChgovrT= parame-ter. When the EconChgovr= parameter is set to “Dry Bulb”, economizer operation is disabled when the OA Temp= parameter indicates a value above the EconChgovrT= parameter by more than this differential. If the EconChgovr= parameter is set to “Enthalpy”, this parameter has no effect on the unit operation. For detailed information regarding economizer changeover operation refer to “Economizer Changeover Method” on page 71.

Max Purge. Max Purge= is an adjustable item which sets the maximum time prior to occupancy that the units purge feature can be activated. This feature functions only when an optional space (or zone) temperature sensor is installed and when a unit internal time schedule is being used. For detailed information regarding the purge feature, refer to “Purge” on page 97.

OA Temp. OA Temp= displays the current temperature reading from the unit mounted outdoor air temperature sen-sor. This sensor is standard on all units.Evap CondensingThe Evap Condensing menu contains parameters that are used to control the evaporative condenser on a unit equipped with the evaporative condensing option. For detailed infor-mation regarding evaporative condenser control, refer to “Evaporative Condenser Control” on page 79.

VFD Speed. VFD Speed= is a status only item that dis-plays the current VFD speed when the evaporative con-denser option includes a VFD to control the first condenser fan on each circuit.

Sump Temp. Sump Temp= is a status only item that dis-plays the current evaporative condenser sump temperature.

Min Fan Speed. Min Fan Speed= is an adjustable item used to set the minimum speed for the VFD speed when the evaporative condenser option includes a VFD to control the first condenser fan on each circuit.

Min SumpT. Min SumpT= is an adjustable item used to set a minimum evaporative condenser sump temperature set point. This value is used to determine when condenser fans are turned off.

Max SumpT. Max SumpT= is an adjustable item used to set a maximum evaporative condenser sump temperature set

point. This value is used to determine when condenser fans are turned on.

Sump Dump Spt. Sump Dump Spt= is an adjustable item used to set a minimum sump temperature. The sump is emp-tied to prevent freezing if the sump temperature drops below this set point.

Stage Time. Stage Time= is an adjustable item used to set a minimum time period between condenser fan stage changes.

Dolphin System. Dolphin System= is an adjustable parameter that indicates to the controller whether or not a Dolphin water treatment method is being used. When set to “yes” the controller assures the sump pump is run every three days to reduce scaling. Discharge HeatingThe Discharge Heating menu contains parameters that relate to or are used to maintain the discharge temperature when the unit is changed over into heating operation. For detailed information regarding heating operation, refer to “Heat/Cool Changeover” on page 67, “Heating: Multistage” on page 83, and “Heating: Modulating” on page 85, as applicable.

Disch Air. Disch Air= is a status only item which displays the current temperature reading from the unit discharge air temperature sensor. This sensor is standard on all units.


Eff Htg Spt. Eff Htg Spt= is a status only item which indi-cates the heating discharge air temperature set point cur-rently in effect during heating operation when the unit is equipped with modulating heating. The heating valve is modulated to maintain the unit discharge air temperature at this set point. This Eff Htg Spt= parameter is raised and low-ered by the controller as necessary to maintain the Eff Htg Spt= in the Zone Heating menu. For detailed information regarding modulating heating operation, refer to“Heating: Modulating” on page 85.

Htg Db. Htg Db= is an adjustable item which sets a dead band around the Eff Htg Spt= parameter. For example, if the Eff Htg Spt= parameter is set to 100ºF and the Htg Db= parameter is set to 2ºF the dead band around the set point would be from 101.0ºF to 99.0ºF.

Min DAT Ctrl. Min DAT Ctrl= is an adjustable item used to activate or deactivate the low discharge temperature limit function available on units equipped with modulating or multistage heat. For detailed information regarding the low discharge temperature limit function, refer to “Discharge Air Low Limit Control” on page 84 (multistage heat) or “Dis-charge Air Low Limit Control” on page 89 (modulating heat) as applicable.

20 McQuay OM 138-3

MinDAT Limit. MinDAT Limit= is an adjustable item which sets the low discharge temperature limit used in the low discharge temperature limit function available on units equipped with modulating or multistage heat. For detailed information regarding the low discharge temperature limit function, refer to “Discharge Air Low Limit Control” on page 84 (multistage heat) or “Discharge Air Low Limit Con-trol” on page 89 (modulating heat) as applicable.

Min Htg Spt. Min Htg Spt= is an adjustable item which sets a minimum heating discharge temperature set point used by the controller to limit the discharge air temperature while controlling the space or zone conditions. For detailed infor-mation on discharge air temperature control, refer to “Heat-ing: Multistage” on page 83 or “Heating: Modulating” on page 85 as applicable.

Max Htg Spt. Max Htg Spt= is an adjustable item which sets a maximum heating discharge temperature set point used by the controller to limit the discharge air temperature while controlling the space or zone conditions. For detailed information on discharge air temperature control, refer to “Heating: Multistage” on page 83 or “Heating: Modulating” on page 85 as applicable.Energy RecoveryThe Energy Recovery menu contains parameters that relate to or are used to control the enthalpy wheel and exhaust fan when a unit is equipped with an optional energy recovery

wheel system. For detailed information regarding the energy recovery control, refer to “Energy Recovery” on page 91.

RF/EF Fan Cap. RF/EF Fan Cap= is a status only item which indicates the current return or exhaust fan capacity. 0-100% inlet vane position is indicated if the unit is equipped with return or exhaust fan variable inlet vanes. 0-100% of VFD maximum speed is indicated if the unit is equipped with a return or exhaust fan VFD.

EF Min Cap. EF Min Cap= is an adjustable item which sets a minimum exhaust fan capacity limit used to start and stop the exhaust fan when a unit is equipped with an optional energy recovery system.

Energy Rec. Energy Rec= is an adjustable item which turns the optional energy recovery system on and off.

ER DAT. ER DAT= is status only item which displays the current discharge air temperature leaving the optional energy recovery wheel.

ER Exh T. ER Exh T= is status only item which displays the current exhaust air temperature leaving the optional energy recovery wheel. Note: This sensor is present only when the unit is equipped with the energy recovery wheel frost protection option.

Table 4: Temperature Menus


Zone Cooling

Control Temp - - -50 - 250.0°FClg Capacity - - 0-100%Eff Clg Spt - - 0.0 - 99.0°F

Occ Clg Spt 75.0°F 1 0.0 - 99.0°FClg Deadband 2.0°F 1 1.0 - 9.9°F

CtrlTemp Src Return 1ReturnSpaceOAT

Space Temp - - 10 - 95.0°FUnoccClg Spt 85.0°F 1 55.0 - 99.0°FUnoccClgDiff 3.0°F 1 1.0 - 10.0°F

Clg Status - -

All ClgEcono

Mech ClgOff AmbOff Alm


OATClg Lock 55°F 1 0 - 100°FOATLock Diff 2°F 1 0 - 10°F

McQuay OM 138-3 21

Zone Heating

Control Temp - - -50 - 250.0°FHtg Capacity - - 0-100%Eff Htg Spt - - 0.0 - 99.0°F

Occ Htg Spt 70.0°F 1 0.0 - 99.0°FHtg Deadband 2.0°F 1 1.0 - 9.9°F

CtrlTemp Src Return 1ReturnSpaceOAT

Space Temp - - 10 - 95.0°FUnoccHtg Spt 55.0°F 1 0.0 - 99.0°FUnoccHtgDiff 3.0°F 1 1.0 - 10.0°F

Htg Status - -

Htg EnaOff AmbOff Alm


OATHtg Lock 55°F 1 0 - 100°FOATLock Diff 1°F 1 0 - 10°F

Discharge Cooling

Disch Air - - -50 - 250.0°FClg Capacity - - 0-100%Eff Clg Spt - - 40.0 - 100.0°F

Clg Db 2.0°F 1 0.0 - 10.0°FMin Clg Spt 55.0°F 1 40.0 - 100.0°FMax Clg Spt 65.0°F 1 40.0 - 100.0°F

OA Damper

OA Damper Pos - - 0-100%Eff Min OA Pos - - 0-100%

OA Flow - - 100-50000 CFM

OA Ambient - -LowHigh

MinOA Type None 1

NoneAuto

Ext mAExt V

DesignFlow No 1NoYes

MinOA Pos 10% 1 0-100%MinOA Flow 2000 CFM 1 100-50000 CFM

MinOA @Max Sig 50% 1 0-100%Min Signal 0% 1 0-100%Max Signal 100% 1 0-100%

MinOA ResetMax 100% 1 0-100%Max Fan Diff 50% 1 0-100%Min Fan Diff 20% 1 0-100%Reset T Limit 0°F 1 0-100°F

EconChgovr Enthalpy 1EnthalpyDry Bulb

EconChgovrT 60°F 1 0 - 99°FEconChgovrDiff 1°F 1 0 - 10°F

Max Purge 60 min 1 0-240 minOA Temp - - -50 - 140.0°F

Table 4: Temperature Menus (Continued)


22 McQuay OM 138-3

HumidityMenus in the Humidity category contain status and control set point parameters that define the dehumidification control setup of the unit. Table 5 on page 23 lists all menus and items in the Humidity group or category. The “Range” col-umn in the table lists all possible values for each item. The factory settings for the adjustable parameters are shown in the “Factory Default Value” column. For detailed informa-tion regarding the dehumidification function refer to “Dehu-midification” on page 89. The following are brief descriptions of the Humidity category menus and items.

DehumidificationThe Dehumidification menu contains status information related to unit dehumidification operation.

Dehum Status. Dehum Status= is a status only item that indicates whether or not dehumidification operation is active.

Rel Humidity. Rel Humidity= is a status only item that dis-plays the current reading from the optional relative humidity sensor.

Dew Point. Dew Point= is a status only item that indicates the current dew point reading calculated based on the current reading from the optional relative humidity sensor.

Evap Condensing

VFD Speed - - 0-100%Sump Temp - - -50 - 140.0°F

Min Fan Speed 25% 1 0-99%Min SumpT 75°F 1 0 - 99°FMax SumpT 85°F 1 0 - 99°F

Sump Dump Spt 35°F 1 0 - 99°FStage Time 10 min 1 0 - 99 min

Dolphin System No 1NoYes

Discharge Heating

Disch Air - - -50 - 250.0°FHtg Capacity - - 0-100%Eff Htg Spt - - 40.0 - 140.0°F

Htg Db 2.0°F 1 0.0 - 10.0°F

Min DAT Ctrl Yes 1NoYes

MinDAT Limit 55.0°F 1 0.0 - 70.0°FMin Htg Spt 60.0°F 1 40.0 - 140.0°FMax Htg Spt 120.0°F 1 40.0 - 140.0°F

Energy Recovery

RF/EF Fan Cap - - 0-100%EF Min Cap 5% 1 0-100%

Energy Rec Yes 1NoYes

ER DAT - - -30.0 - 200.0°FER ExhT - - -30.0 - 200.0°F

Table 4: Temperature Menus (Continued)


Table 5: Humidity Menus


Dehumidification

Dehum Status - -Rel Humidity - -

Dew Point - -

Dehum Method None 1NoneRH

DewPntRH Setpoint 50% 1 0-99%

DewPoint Spt 50°F 1 0.0-99.0°FRH Db 2% 1 0-10%

DewPnt Db 2°F 1 0-10°F

Reheat Unit RH Only 1Unit RH OnlyAux RH Only

Unit and Aux RH

McQuay OM 138-3 23

Dehum Method. Dehum Method= is an adjustable item used to turn the de humid if action function on and off and to select whether dehumidification operation is based on rela-tive humidity or dew point.

RH Setpoint. RH Setpoint= is an adjustable item that sets the relative humidity set point used when the Dehum Method= parameter is set to “RH”.

DewPoint Spt. DewPoint Spt= is an adjustable item that sets the dew point set point used when the Dehum Method= parameter is set to “DewPnt”.

RH Db. RH Db= is an adjustable item that sets a dead band around the relative humidity set point. For example, if the RH Setpoint= parameter is set to 50% and the RH Db= parameter is set to 2% the dead band around the set point would be from 48% to 52%.

DewPnt Db. DewPnt Db= is an adjustable item that sets a dead band around the dew point set point. For example, if the DewPoint Spt= parameter is set to 50ºF and the DewPnt Db= parameter is set to 2ºF the dead band around the set point would be from 48ºF to 52ºF.

Reheat. Reheat= is an adjustable item that defines the unit reheat arrangement used during dehumidification reheat operation. Refer to “Dehumidification Heating Operation” on page 90 for details regarding defining the unit reheat arrangement.

SchedulesMenus in the Schedules category contain status and control set point parameters that relate to scheduling the start stop of the unit. Table 6 on page 25 lists all menus and items in the Schedules group or category. The “Range” column in the table lists all possible values for each item. The factory set-tings for the adjustable parameters are shown in the “Factory Default Value” column. The following are brief descriptions of the Schedules category menus and items. For detailed information regarding scheduling the start/stop of the unit, refer to “Auto/Manual Operation” on page 47 and “Schedul-ing” on page 51.Daily ScheduleThe Daily Schedule menu contains parameters for setting the daily internal start stop schedule for the unit.Mon. Mon= is an adjustable item which sets one start and one stop time for Monday.Tue. Tue= is an adjustable item which sets one start and one stop time for Tuesday.Wed. Wed= is an adjustable item which sets one start and one stop time for Wednesday.Thu. Thu= is an adjustable item which sets one start and one stop time for Thursday.Fri. Fri= is an adjustable item which sets one start and one stop time for Friday.

Sat. Sat= is an adjustable item which sets one start and one stop time for Saturday.Sun. Sun= is an adjustable item which sets one start and one stop time for Sunday.Hol. Hol= is an adjustable item which sets one start and one stop time for Holidays.

One Event Schedule

The One Event Schedule menu contains parameters for set-ting a beginning and ending date and time for a one event schedule which overrides the daily internal start stop sched-ule for that period.

Beg. Beg= is an adjustable item which sets the start date and time for a one event schedule which overrides the daily inter-nal start stop schedule for the period defined by it and the End= parameter.

End. End= is an adjustable item which sets the stop date and time for a one event schedule which overrides the daily inter-nal start stop schedule for the period defined by it and the Beg= parameter.Holiday ScheduleThe Holiday Schedule menu contains parameters for defin-ing up to 16 holiday periods throughout the year. A begin-ning and ending date is assigned to each holiday period. On each day of the holiday period, the holiday schedule entered in the Daily Schedules menu is used.Hol 1 through Hol 16. Hol 1= through Hol 16= are adjustable items which are used to define up to 16 holiday periods throughout the calendar year.Optimal StartThe Optimal Start menu contains parameters for adjusting the action of the optimal start function. For detailed informa-tion regarding the optimal start function, refer to “Optimal Start” on page 52.Space Temp. Space Temp= is a status only item which dis-plays the current space (or zone) temperature reading from the optional unit space air temperature sensor input. Refer to “Zone (Space) Temperature Sensor” on page 59.Note: If an optional space temperature sensor is not

installed, the Space Sensor= item in the Unit Con-figuration menu should be set to “No” to disable the alarm function associated with an open circuit at the space temperature sensor input.

Optimal Start. Optimal Start= is an adjustable item used to turn the optimal start function on and off.

Auto Update. Auto Update= is an adjustable item used to turn on and off a feature included in the optimal start func-tion where the controller “learns” and updates the optimal start parameters automatically based on previous results.

Htg Rate. Htg Rate= is an adjustable item used by the con-troller in determining the amount time before occupancy to start when the Optimal Start= parameter is set to “On.”

24 McQuay OM 138-3

Htg OAT. Htg OAT= is an adjustable item used by the con-troller in determining the amount time before occupancy to start when the Optimal Start= parameter is set to “On.”

Htg Zero OAT. Htg Zero OAT= is an adjustable item used by the controller in determining the amount time before occupancy to start when the Optimal Start= parameter is set to “On.”

Clg Rate. Clg Rate= is an adjustable item used by the con-troller in determining the amount time before occupancy to start when the Optimal Start= parameter is set to “On.”

Clg OAT. Clg OAT= is an adjustable item used by the con-troller in determining the amount time before occupancy to start when the Optimal Start= parameter is set to “On.”

Clg Zero OAT. Clg Zero OAT= is an adjustable item used by the controller in determining the amount time before occupancy to start when the Optimal Start= parameter is set to “On.”

Table 6: Schedules Menus


Daily Schedule

Mon

00 1 00 - 2300 2 00 - 5900 3 00 - 2300 4 00 - 59

Tue Same As Monday Same As Monday Same As MondayWed Same As Monday Same As Monday Same As MondayThu Same As Monday Same As Monday Same As MondayFri Same As Monday Same As Monday Same As MondaySat Same As Monday Same As Monday Same As MondaySun Same As Monday Same As Monday Same As MondayHol Same As Monday Same As Monday Same As Monday

One Event Schedule

Beg N/A

1 Jan-Dec2 01-313 00-234 00-59

End N/A

1 Jan-Dec2 01-313 00-234 00-59

Holiday Schedule

Hol 1 N/A-N/A

1 Jan-Dec2 01-313 Jan-Dec4 01-31

Hol 2 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 3 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 4 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 5 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 6 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 7 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 8 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 9 Same As Hol 1 Same As Hol 1 Same As Hol 1

Hol 10 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 11 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 12 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 13 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 14 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 15 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 16 Same As Hol 1 Same As Hol 1 Same As Hol 1

McQuay OM 138-3 25

Setup/ServiceMenus in the Setup/Service category contain status and con-trol parameters that relate to the setup and service of the unit. Parameters in these menus are generally the type that are set at the factory and might be adjusted when the equipment is started up and generally do not required further adjustment. Table 7 on page 36 lists all menus and items in the Setup/Service group or category. The “Range” column in the table lists all possible values for each item. The factory set-tings for the adjustable parameters are shown in the “Factory Default Value” column. The following are brief descriptions of the Setup/Service category menus and items.Unit ConfigurationThe Unit Configuration menu contains parameters that define various basic unit configuration attributes.

AHU ID. AHU ID= is a status only item which identifies the version of application software loaded into the unit main control board (MCB). Refer to “Software Identification and Configuration” on page 110.

CCB1 ID. CCB1 ID= is a status only item which identifies the version of application software loading into the CCB1 auxiliary control board. Refer to“Software Identification and Configuration” on page 110.

CCB2 ID. CCB2 ID= is a status only item which identifies the version of application software loading into the CCB2 auxiliary control board. Refer to “Software Identification and Configuration” on page 110.

GCB1 ID. GCB1 ID= is a status only item which identifies the version of application software loading into the GCB1 auxiliary control board. “Software Identification and Config-uration” on page 110.

EHB1 ID. EHB1 ID= is a status only item which identifies the version of application software loading into the EHB1

auxiliary control board. “Software Identification and Config-uration” on page 110.

ERB1 ID. ERB1 ID= is a status only item which identifies the version of application software loading into the ERB1 auxiliary control board. Refer to “Software Identification and Configuration” on page 110.

Calibrate Mode. Calibrate Mode= is an adjustable item used to place the unit into the Calib operating state. In this state the unit is shut off and all the unit actuator feedback signals are calibrated. The unit static pressure sensor input signals are also zeroed during this state. For detailed infor-mation regarding calibration, refer to “Calibrate Mode” on page 58.

Space Sensor. Space Sensor= is an adjustable item used to indicate whether or not an optional space air temperature sensor is installed. Setting this parameter to “No” disables the alarm function associated with an open circuit at the space temperature sensor input. Also, if “No” is selected, the Cntl Temp Src= parameter cannot be set to “Space” and the Clg Reset= and the Htg Reset= parameters cannot be set to “Space.” For more information regarding the optional space temperature sensor, refer to “Zone (Space) Temperature Sen-sor” on page 59.

EFT Sensor. EFT Sensor= is an adjustable item used to indicate whether or not an optional entering fan air tempera-ture sensor is installed. Setting this parameter to “No” dis-ables the alarm function associated with an open circuit at the EFT temperature sensor input. This sensor is installed only on units equipped with either gas or electric heat and is used by the controller to calculate the heat rise across the heat exchanger by comparing it to the discharge air tempera-ture input. The controller uses this information to protect the heat exchanger against overheating.

Optimal Start

Space Temp - - 10 - 95.0°F

Optimal Start No 1NoYes

Auto Update Yes 1NoYes

Htg Rate 0.4°F/min 1 0.0 - 1.0°F/minHtg OAT 35°F 1 0 - 255°F

Htg Zero OAT 0°F 1 -40 - 60°FClg Rate 0.4°F/min 1 0.0 -1.0°F/minClg OAT 85°F 1 0 - 255°F

Clg Zero OAT 100°F 1 60 - 140°F

Table 6: Schedules Menus (Continued)


26 McQuay OM 138-3

2nd P Sensor. 2nd P Sensor= is an adjustable item used to indicate whether or not an optional building static pressure sensor is installed in a unit. When this parameter is set to “Bldg”, the controller assumes there is a building static pres-sure sensor wired to the “second sensor” location.

Note: One a zone (or space comfort) control unit, there is not “first sensor” location.

In this case the unit return inlet vanes or VFD are controlled to maintain the building pressure at a building pressure set point. When this parameter is set to “None”, the controller assumes there is not a second static pressure sensor installed and ignores the associated analog input. For detailed infor-mation regarding return fan capacity control, “Return Fan Capacity Control” on page 94.

RF/EF Ctrl. RF/EF Ctrl= is an adjustable item used to select the type of return or exhaust fan airflow control to be used. If the unit is equipped with return fan inlets vanes or a VFD and this parameter is set to “Tracking”, then the return fan airflow is controlled based on an adjustable tracking rela-tionship between the discharge fan and return fan airflow. If this parameter is set to “Bldg”, then the return or exhaust fan airflow is controlled independently of the discharge fan air-flow to maintain the building static pressure at a building static pressure set point. If this parameter is set to “Position”, then the return or exhaust fan airflow is controlled to an inlet vane position or VFD speed set point set by the Rem RF/EF Cap= parameter. For detailed information regarding return or exhaust fan capacity control, refer to “Return Fan Capac-ity Control” on page 94 or “Energy Recovery” on page 91.

Rem RF/EF Cap. Rem RF/EF Cap= is an adjustable item which adjusts the return/exhaust air vane position or VFD speed when the RF/EF Ctrl= parameter is set to “Position.” This parameter can be manually adjusted or set via a network signal. It is also used when the Fan Balance= parameter is set to “On” to manually position the return fan vanes or VFD during the fan balance procedure. For detailed information regarding return or exhaust fan capacity control, refer to “Return Fan Capacity Control” on page 94 or “Energy Recovery” on page 91.

Eng Units. Eng Units= is an adjustable item used to select the system of engineering units used for displaying data on the keypad. If this parameter is set to “English”, the keypad data is displayed in inch-pound (I-P) units of measurement. If this parameter is set to “SI Canada”, the keypad data is displayed in the International System of Units (SI) used in Canada. If this parameter is set to “SI Europe”, the keypad data is displayed in the International System of Units (SI) used in Europe.Configuration CodeThe Configuration Code menu contains parameters that indi-cate the current Software Configuration Code that is pro-grammed into the unit controller. For details regarding the unit Software Configuration Code, refer to “Software Identi-fication and Configuration” on page 110.

Pos # 1-4. Pos # 1-4= is a status only item that displays the first through fourth digits of the Software Configuration Code currently loaded into the unit. Note: The decimal point in the display is to be disregarded.

Pos # 5-8. Pos # 5-8= is a status only item that displays the fifth through eighth digits of the Software Configuration Code currently loaded into the unit. Note: The decimal point in the display is to be disregarded.

Pos # 9-12. Pos # 9-12= is a status only item that displays the ninth through twelfth digits of the Software Configura-tion Code currently loaded into the unit. Note: The decimal point in the display is to be disregarded.

Pos # 13-16. Pos # 13-16= is a status only item that dis-plays the thirteenth through sixteenth digits of the Software Configuration Code currently loaded into the unit. Note: The decimal point in the display is to be disregarded.

Pos # 17-20. Pos # 17-20= is a status only item that dis-plays the seventeenth through twentieth digits of the Soft-ware Configuration Code currently loaded into the unit. Note: The decimal point in the display is to be disregarded.

Pos # 21-22. Pos # 21-22= is a status only item that dis-plays the twenty first through twenty second digits of the Software Configuration Code currently loaded into the unit. Note: The decimal point in the display is to be disregarded. PasswordsThe “Passwords” menu contains parameters that relate to the keypad passwords. For detailed information regarding pass-words, refer to “Password Protection” on page 9.

Timeout. Timeout= is an adjustable item used to set the duration of a timer which is set whenever the keypad pass-word is entered. Once the password is entered, set points can be changed and alarms can be cleared without reentering the password until this time expires.

Clear Alarm. Clear Alarm= is an adjustable item used to set which password level is required to allow the user to clear alarms. If this parameter is set to “Lvl 1” then at least the level 1 password must be entered to allow alarms to be cleared. If this parameter is set to “Lvl 2” then the level 2 password must be entered to allow alarms to be cleared. If this parameter is set to “None” then a password entry is not required to allow alarms to be cleared.Operating HoursThe Operating Hours menu contains items that indicate how many hours the fans, cooling and heating, override and energy recover have been operating. This information can be used for scheduling maintenance and monitoring unit operation.

Fan. Fan= is a status item which indicates the hours that the unit fans have operated. This value accumulates to 65,535 hours before rolling over. This status item can be reset or adjusted manually from the keypad.

McQuay OM 138-3 27

Mech Cool. Mech Cool= is a status item which indicates the hours that the unit mechanical cooling has operated. This value accumulates to 65,535 hours before rolling over. This status item can be reset or adjusted manually from the keypad.

Comp 1. Comp 1= is a status item which indicates the hours compressor #1 has operated on units equipped with compressorized cooling. This value accumulates to 65,535 hours before rolling over. This status item can be reset or adjusted manually from the keypad.




Comp 5. Comp 5= is status item which indicates the hours compressor #5 has operated on units equipped with compres-sorized cooling. This value accumulates to 65,535 before rolling over. This status item can be reset or adjusted manu-ally from the keypad.

Comp 6. Comp 6= is status item which indicates the hours compressor #6 has operated on units equipped with compres-sorized cooling. This value accumulates to 65,535 before rolling over. This status item can be reset or adjusted manu-ally from the keypad.

Heating. Heating= is a status item which indicates the hours that the unit heating has operated. This value accumu-lates to 65,535 hours before rolling over. This status item can be reset or adjusted manually from the keypad.

Economizer. Economizer= is a status item which indicates the hours that the unit has been in the Econo operating state. This value accumulates to 65,535 hours before rolling over. This status item can be reset or adjusted manually from the keypad.

Tnt Ovrd. Tnt Ovrd= is a status item which indicates the hours that the unit has operated in the schedule tenant over-ride mode of operation. This value accumulates to 65,535 hours before rolling over. This status item can be reset or adjusted manually from the keypad.

Dehumidify. Dehumidify= is a status item which indicates the hours that the dehumidification function has operated.

This value accumulates to 65,535 hours before rolling over. This status item can be reset or adjusted manually from the keypad.

ERecovery. ERecovery= is a status item which indicates the hours that the optional energy recovery system has been in operation. This value accumulates to 65,535 hours before rolling over. This status item can be reset or adjusted manu-ally from the keypad.Timer SettingsThe Timer Settings menu contains several parameters for setting the controller process timers. For detailed informa-tion regarding these timers, refer to “Control Timer Settings” on page 60.

Service. Service= is an adjustable item which sets a time period during which many of the controller process timers, such as the cooling and heating interstage timers, are sped up. Once this parameter is set to a none-zero time value the fast timers are used until this timer expires.

Recirculate. Recirculate= is an adjustable item which defines the duration of the Recirc operating state.

Low DAT. Low DAT= is an adjustable item which sets the duration of a time period after unit start up during which the Lo Disch Tmp fault is ignored.

Max MWU. Max MWU= is an adjustable item which sets a maximum duration for the MWU (morning warm up) operat-ing state.

Tnt Ovrd. Tnt Ovrd= is an adjustable item which sets the time period during which the unit operates each time the ten-ant override button on the optional space temperature sensor is pressed or the Occ Mode= parameter is switched to “Tnt Ovrd.” For detailed information regarding tenant override operation refer to “Tenant Override” on page 50.

Start Init. Start Init= is an adjustable item which sets the duration of the Startup operating state.Time/DateThe Time/Date menu contains three parameters for setting the controller current date and time. For detailed information regarding these parameters, refer to “Setting Controller Date and Time” on page 51.

Time. Time= is an adjustable item which sets the controller current time.

Note: The time must be entered and is displayed in “mili-tary” time (hh:mm:ss).

Day. Day= is a status only item which displays the current day of the week based on the value of the Date= parameter.

Date. Date= is an adjustable item which sets the current date including date, month and year.

28 McQuay OM 138-3

Bldg Static P SetupThe Bldg Static P Setup menu contains several adjustable parameters which affect the response timing for the PID con-trol action used by the controller when modulating the return or exhaust fan inlet vanes or VFD to maintain building static pressure. These parameters apply only when the RF/EF Ctrl= parameter in the Unit Configuration menu is set to “BldgPres.” For detailed information regarding these control parameters, refer to “MicroTech II DDC Features” on page 107.

BSP Propbd. BSP Propbd= is an adjustable item which sets the “proportional band” used in the PID control function that modulates the return air or exhaust fan inlet vanes or VFD in response to building static pressure. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the return or exhaust fan inlet vanes or VFD.

BSP IntTime. BSP IntTime= is an adjustable item which sets the “integral time” used in the PID control function that modulates the return air or exhaust fan inlet vanes or VFD in response to building static pressure. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the return or exhaust fan inlet vanes or VFD.

BSP Period. BSP Period= is an adjustable item which sets the “sampling period” used in the PID control function that modulates the return air or exhaust fan inlet vanes or VFD. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the return or exhaust fan inlet vanes or VFD.

PRAC. PRAC= is an adjustable item used to automatically tune the building static pressure control PID parameters. In general this parameter should be left in the “No” setting and should be used only if there are problems with building static pressure control using the default PID parameters. For detailed information regarding the PRAC function refer to “MicroTech II DDC Features” on page 107.Exhaust Fan SetupThe Exhaust Fan Setup menu contains several adjustable parameters that affect the control of propeller exhaust fans when a unit is equipped with the propeller exhaust fan option. For detailed information regarding propeller exhaust fan operation, refer “Propeller Exhaust Fan Control” on page 95.

Min Exh Fan Cap. Min Exh Fan Cap= is an adjustable item used to determine when the propeller exhaust fans are turned off when a unit is equipped with the propeller exhaust fan option. The exhaust fans are shut off when the building static pressure is below the set point by more than half the dead band and the RF/EF Fan Cap= value has been below this setting for longer than the Min Stop Time= setting.

Min OA Dmpr. Min OA Dmpr= is an adjustable item used to set an outdoor damper position minimum value for propel-

ler fan operation when a unit is equipped with the propeller exhaust fan option. The propeller fans will not be turned on unless the outdoor air damper position exceeds this value.

Min DF Cap. Min DF Cap= is an adjustable item used on VAV units to set a discharge fan capacity minimum value for propeller fan operation when a unit is equipped with the pro-peller exhaust fan option. The propeller fans will not be turned on unless the Disch Fan Cap= value exceeds this value (or the unit has a constant volume discharge fan).

Min Strt Time. Min Strt Time= is an adjustable item used to set a minimum time period before starting the propeller exhaust fans when a unit is equipped with the propeller exhaust fan option. The propeller fans will not be turned on unless all the conditions required for starting the exhaust fans have been met for at least this time period.

Min Stop Time. Min Stop Time= is an adjustable item used to set a minimum time period before stopping the propeller exhaust fans when a unit is equipped with the propeller exhaust fan option. Once started, the propeller fans will not be turned off unless the RF/EF Fan Cap= value has be at or below the Min Exh Fan Cap= setting for longer than this time period.Zone Temp SetupThe Zone Temp Setup menu contains several adjustable parameters which affect the response timing for the PID con-trol action used by the controller when adjusting the Eff Clg Spt= and Eff Htg Spt= parameters in the Discharge Cooling and Discharge Heating menus to maintain the Eff Clg Spt= and Eff Htg Spt= set points in the Zone Cooling and Zone Heating menus. For detailed information regarding PID con-trol parameters, refer to “MicroTech II DDC Features” on page 107.

Spt Source. Spt Source= is an adjustable item which deter-mines the source for setting the Eff Clg Spt= and Eff Htg Spt= set points in the Zone Cooling and Zone Heating menu. When this parameter is set “Keypad”, the Eff Clg Spt= and Eff Htg Spt= set points in the Zone Cooling and Zone Heat-ing menus are set to the Occ Clg Spt= and Occ Htg Spt= val-ues respectively. When this parameter is set “Tstat”, the Eff Clg Spt= and Eff Htg Spt= set points in the Zone Cooling and Zone Heating menus are set based on an analog set point adjustment input from a optional remotely mounted space temperature sensor. For details regarding the use of thermo-stat supplied set points, refer to “Tstat Source Set Points” on page 68.

Clg Propbd. Clg Propbd= is an adjustable item which sets the “proportional band” used in the PID control function that adjusts the Eff Clg Spt= parameter in the Discharge Cooling menu to maintain the Eff Clg Spt= set point in the Zone Cooling menu. In general, increasing this value has a slow-ing effect and decreasing this value has a speeding effect on this control action.

McQuay OM 138-3 29

Htg Propbd. Htg Propbd= is an adjustable item which sets the “proportional band” used in the PID control function that adjusts the Eff Htg Spt= parameter in the Discharge Heating menu to maintain the Eff Htg Spt= set point in the Zone Heating menu. In general, increasing this value has a slow-ing effect and decreasing this value has a speeding effect on this control action.

Clg IntTime. Clg IntTime= is an adjustable item which sets the “integral time” used in the PID control function that adjusts the Eff Clg Spt= parameter in the Discharge Cooling menu to maintain the Eff Clg Spt= set point in the Zone Cooling menu. In general, increasing this value has a slow-ing effect and decreasing this value has a speeding effect on this control action.

Htg IntTime. Htg IntTime= is an adjustable item which sets the “integral time” used in the PID control function that adjusts the Eff Htg Spt= parameter in the Discharge Heating menu to maintain the Eff Htg Spt= set point in the Zone Heating menu. In general, increasing this value has a slow-ing effect and decreasing this value has a speeding effect on this control action.

Period. Period= is an adjustable item which sets the “period” used in the PID control function that adjusts the Eff Clg Spt= and Eff Htg Spt= parameters in the Discharge Cooling and Discharge Heating menus to maintain the Eff Clg Spt= and Eff Htg Spt= set points in the Zone Cooling and Zone Heating menus. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on this control action.Compressor SetupThe Compressor Setup menu contains several adjustable parameters than affect the compressor and condenser fan staging on units equipped with compressorized cooling. For detailed information regarding compressorized cooling stag-ing operation, refer to “Cooling: Multistage” on page 75.

Lead Circuit. Lead Circuit= is an adjustable item used to select the lead cooling circuit or to select automatic lead/lag of the cooling circuits. For detailed information regarding cooling circuit lead/lag operation, refer to “Compressor Staging” on page 76.

CompCtrl. CompCtrl= is an adjustable item used to select the circuit staging method to be use during cooling opera-tion. When this parameter is set to “Cross Circ”, cooling is staged up and down alternating between cooling circuit #1 and #2. When this parameter is set to “Lead Load”, the “lead” cooling circuit is first staged up completely before the second cooling circuit is staged up. For detailed information regarding circuit staging operation, refer to “Compressor Staging” on page 76.

Cond Fan1 Spt. Cond Fan1 Spt= is an adjustable item used to set the outdoor air temperature point above which the first condenser fan in each cooling circuit is turned on.

Cond Fan2 Spt. Cond Fan2 Spt= is an adjustable item used to set the outdoor air temperature point above which the second condenser fan in each cooling circuit is turned on.

Cond Fan3 Spt. Cond Fan3 Spt= is an adjustable item used to set the outdoor air temperature point above which the third condenser fan in each cooling circuit is turned on.

Cond Fan4 Spt. Cond Fan4 Spt= is an adjustable item used to set the outdoor air temperature point above which the fourth condenser fan in each cooling circuit is turned on.

Stage Time. Stage Time= is an adjustable item used to set the minimum time between consecutive cooling staging actions.Chilled Water SetupThe Chilled Water Setup menu contains several adjustable parameters that affect the response timing for the PID con-trol action used by the controller when modulating the chilled water valve to maintain the Eff Clg Spt= parameter in the Discharge Cooling menu. For detailed information regarding these control parameters, refer to “MicroTech II DDC Features” on page 107.

Clg Propbd. Clg Propbd= is an adjustable item which sets the “proportional band” used in the PID control function that modulates the chilled water valve to maintain the Eff Clg Spt= parameter in the Discharge Cooling menu. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the chilled water valve.

Clg IntTime. Clg IntTime= is an adjustable item which sets the “integral time” used in the PID control function that modulates the chilled water valve to maintain the Eff Clg Spt= parameter in the Discharge Cooling menu. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the chilled water valve.

Clg Period. Clg Period= is an adjustable item which sets the “sampling period” used in the PID control function that modulates the chilled water valve to maintain the Eff Clg Spt= parameter in the Discharge Cooling menu. In general, increas-ing this value has a slowing effect and decreasing this value has a speeding effect on the control of the chilled water valve.

PRAC. PRAC= is an adjustable item used to automatically tune the chilled water valve control PID parameters on units equipped with chilled water coils. In general this parameter should be left in the “No” setting and should be used only if there are problems with chilled water valve control using the default PID parameters. For detailed information regarding the PRAC function refer to “MicroTech II DDC Features” on page 107.

Stage Time. Stage Time= is an adjustable item used to set a minimum cooling time period. Once a unit enters the Cool-ing operating state, the chilled water valve must be closed for this time period before the unit leaves the Cooling operat-ing state.

30 McQuay OM 138-3

Feedback. Feedback= is an adjustable item used to config-ure the chilled water cooling valve actuator feedback signal on a unit equipped with chilled water cooling. If this item is set to “2 Wire” the controller expects a 0-500Ω resistive sig-nal from the actuator. If this item is set to “3 Wire” the con-troller expects a 0-5VDC signal from the actuator.Economizer SetupThe Economizer Setup menu contains several adjustable parameters that affect the response timing for the PID con-trol action used by the controller when modulating the econ-omizer dampers to maintain the Eff Clg Spt= parameter in the Discharge Cooling menu. For detailed information regarding these control parameters, refer to “MicroTech II DDC Features” on page 107.

Clg Propbd. Clg Propbd= is an adjustable item which sets the “proportional band” used in the PID control function that modulates the economizer dampers to maintain the Eff Clg Spt= parameter in the Discharge Cooling menu. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the dampers.

Clg IntTime. Clg IntTime= is an adjustable item which sets the “integral time” used in the PID control function that modulates economizer dampers to maintain the Eff Clg Spt= parameter in the Discharge Cooling menu. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the dampers.

Clg Period. Clg Period= is an adjustable item which sets the “sampling period” used in the PID control function that modulates economizer dampers to maintain the Eff Clg Spt= parameter in the Discharge Cooling menu. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the dampers.

PRAC. PRAC= is an adjustable item used to automatically tune the economizer control PID parameters on units equipped with an economizer. In general this parameter should be left in the “No” setting and should be used only if there are problems with economizer control using the default PID parameters. For detailed information regarding the PRAC function refer to “MicroTech II DDC Features” on page 107.

Feedback. Feedback= is an adjustable item used to config-ure the outdoor air damper actuator feedback signal. If this item is set to “2 Wire” the controller expects a 0-500Ω resis-tive signal from the actuator. If this item is set to “3 Wire” the controller expects a 0-5VDC signal from the actuator.DesignFlow SetupThe DesignFlow Setup menu contains several adjustable parameters that affect the response timing for the control action used by the controller when modulating the outdoor

air dampers to maintain the MinOA Flow= setting. For detailed information regarding these control parameters, refer to “DesignFlow OA Airflow Measurement Reset” on page 73.

Wait Time. Wait Time= is an adjustable item which sets the “wait time” used in the control function that modulates the Eff Min OA Pos= parameter to maintain the OA Flow= parameter at the MinOA Flow= set point when a unit is equipped with the optional DesignFlow outdoor airflow measuring feature. For details regarding the DesignFlow option, refer to “Minimum Ventilation Control” on page 69.

Modband. Modband= is an adjustable item which sets the “modulation band” used in the control function that modu-lates the Eff Min OA Pos= parameter to maintain the OA Flow= parameter at the MinOA Flow= set point when a unit is equipped with the optional DesignFlow outdoor airflow measuring feature. For details regarding the DesignFlow option, refer to “Minimum Ventilation Control” on page 72.

Wait Time. Wait Time= is an adjustable item which sets the “wait time” used in the control function that modulates the Eff Min OA Pos= parameter to maintain the OA Flow= parameter at the MinOA Flow= set point when a unit is equipped with the optional DesignFlow outdoor airflow measuring feature.

Max Step. Max Step= is an adjustable item which sets the “maximum step” used in the control function that modulates the Eff Min OA Pos= parameter to maintain the OA Flow= parameter at the MinOA Flow= set point when a unit is equipped with the optional DesignFlow outdoor airflow measuring feature.

Deadband. Deadband= is an adjustable item which sets the “deadband” used in the control function that modulates Eff Min OA Pos= parameter to maintain the OA Flow= parameter at the MinOA Flow= set point when a unit is equipped with the optional DesignFlow outdoor airflow measuring feature.

LH Lvl Pos. LH Lvl Pos= is a status item which is used calibrate the left-hand side (unit opposite drive side) of the optional DesignFlow outdoor measuring apparatus. For details regarding calibration of the DesignFlow apparatus, refer to the applicable model-specific installation and main-tenance manual (refer to Table 1 on page 3).

RH Lvl Pos. RH Lvl Pos= is a status item which is used calibrate the right-hand side (unit drive side) of the optional DesignFlow outdoor measuring apparatus. For details regarding calibration of the DesignFlow apparatus, refer to the applicable model-specific installation and maintenance manual (refer to Table 1 on page 3).

McQuay OM 138-3 31

AI11 Reference. AI Reference= is an adjustable item used to configure analog input # 11 (AI11) when a unit is equipped with the Design Flow OA airflow measuring option. This item must be set to “No” when the unit is equipped with a “precision” 5 VDC power supply (McQuay PN 111049610) for use with the Design Flow option. In this case, analog input AI11 is not used to determine the current outdoor airflow value. This item must be set to “Yes” on older units which are not equipped with a “precision” 5 VDC power supply (McQuay PN 111049601) for use with the Design Flow option. In this case, analog input AI11 is used to determine the current outdoor airflow value.Heating SetupThe Heating Setup menu contains several adjustable parame-ters that affect the control action used by the controller to modulate the heating and/or face and bypass damper control actuator to maintain the Eff Htg Spt= parameter in the Dis-charge Heating menu.

Stage Time. Stage Time= is an adjustable item used to set a minimum time period between heating staging actions.

F&BP Ctrl. F&BP Ctrl= is an adjustable item used to determine the type of heating valve control to be used on units equipped with face and bypass heating. For detailed information regarding heating face and bypass operation, refer to “Steam or Hot Water Heat: Face and Bypass Damper Control-Open Valve Method” on page 86.

F&BP Chgovr. F&BP Chgovr= is an adjustable item used to determine when the heating valve is driven fully open when the F&BP Ctrl= parameter is set to “ModValve.” For detailed information regarding heating face and bypass oper-ation, refer to “Steam or Hot Water Heat: Face and Bypass Damper Control-Open Valve Method” on page 86.

Htg Propbd. Htg Propbd= is an adjustable item which sets the “proportional band” used in the PID control function that modulates the heating valve or face and bypass dampers to maintain the Eff Htg Spt= parameter in the Discharge Heat-ing menu. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the heating or face and bypass damper control actuator. For detailed information on this PID control parameter, refer to “MicroTech II DDC Features” on page 107.

Htg IntTime. Htg IntTime= is an adjustable item which sets the “integral time” used in the PID control function that modulates the heating valve or face and bypass dampers to maintain the Eff Htg Spt= parameter in the Discharge Heat-ing menu. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the heating or face and bypass damper control actuator. For detailed information on this PID control parameter, refer to “MicroTech II DDC Features” on page 107.

Htg Period. Htg Period= is an adjustable item which sets the “sampling period” used in the PID control function that modulates the heating valve or face and bypass dampers to maintain the Eff Htg Spt= parameter in the Discharge Heat-

ing menu. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the heating or face and bypass damper control actuator. For detailed information on this PID control param-eter, refer to “MicroTech II DDC Features” on page 107.

PRAC. PRAC= is an adjustable item used to automatically tune the heating valve control PID parameters on unit equipped with modulating heat. In general this parameter should be left in the “No” setting and should be used only if there are problems with heating valve control using the default PID parameters. For detailed information regarding the PRAC function refer to “MicroTech II DDC Features” on page 107.

Feedback. Feedback= is an adjustable item used to config-ure the heating valve actuator feedback signal on a unit equipped with hot water or steam heat. If this item is set to “2 Wire” the controller expects a 0-500Ω resistive signal from the actuator. If this item is set to “3 Wire” the controller expects a 0-5VDC signal from the actuator. Gas Act High. Gas Act High= is an adjustable parameter that allows calibration of the modulating gas valve actuator feedback signal on a unit equipped with modulating gas heat. This value can be increased or decreased in small increments so that the Htg Capacity= indicates exactly 100% when the gas valve is fully open. Energy Rec SetupThe Energy Rec Setup menu contains several adjustable parameters that affect the control of the energy recovery wheel on units equipped with an energy recovery system. For detailed information regarding these control parameters, refer to “Energy Recovery” on page 91.

Min ExhT Diff. Min ExhT Diff= is an adjustable item used to determine when the energy recovery wheel should be slowed down and turned off to protect against wheel frosting when the unit is equipped with the energy recovery wheel frost protection option.

Max ExhT Diff. Max ExhT Diff= is an adjustable item used to determine when the energy recovery wheel should be restarted or sped back up after being turned off or slowed down to protect against wheel frosting when the unit is equipped with the energy recovery wheel frost protection option.

Stage Time. Stage Time= is an adjustable item used to set a minimum time period between slowing, stopping and increasing the energy recovery wheel speed when a unit is equipped with the energy recovery wheel frost protection option.

Min Off Time. Min Off Time= is an adjustable item used to set a minimum time period before restarting the energy recovery wheel when it has been turned off to protect against wheel frosting when a unit is equipped with the energy recovery wheel frost protection option.

32 McQuay OM 138-3

Min Exh On. Min Exh On= is an adjustable item used to set a minimum on time for the exhaust fan when a unit is equipped with an optional energy recovery system.

Min Exh Off. Min Exh Off= is an adjustable item used to set a minimum off time for the exhaust fan when a unit is equipped with an optional energy recovery system. Dehum SetupThe Dehum Setup menu contains several adjustable parame-ters that affect the control action of the dehumidification function. For detailed information regarding the dehumidifi-cation control function, for detailed information regarding the dehumidification function, refer to “Dehumidification” on page 89.

Dehum Ctrl. Dehum Ctrl= is an adjustable item which determines when the dehumidification function is allowed to operate. If this parameter is set to “Occupied”, the dehumidi-fication function is only allowed to operate during occupied time periods. If this parameter is set to “Always”, the dehu-midification is allowed to operate during occupied and unoc-cupied time periods.

Minimum Stages. Minimum Stages= is an adjustable item which sets the number of cooling stages that are immediately activated upon a call for dehumidification operation.

Maximum Stages. Maximum Stages= is an adjustable item which sets the maximum number of cooling stages that are activated during dehumidification operation.

DH Stage Time. DH Stage Time= is an adjustable item which sets a stage time period between the minimum and maximum cooling stages during dehumidification operation. When the controller initially activates dehumidification operation, cooling is staged up to the Minimum Stages= value and this timer beings to time out. After this timer expires, cooling is staged up to the Maximum Stages= value if there is still a call for dehumidification.

Sensor Loc. Sensor Loc= is an adjustable item which determines which temperature sensor is used in combination with the relative humidity sensor input to calculate the dew point value. This parameter can either be set to “Space” or “Return”.Manual ControlThe Manual Control menu contains parameters used to con-trol the outputs from the controller (MCB) in a manual mode. This can be used to test the operation of the various devices controlled by the outputs. For detailed information regarding manual operation, refer to “Manual Output Con-trol” on page 61.

Manual Control. Manual Control= is an adjustable item used to turn the manual control mode of operation on and off. When this parameter is set to “No” the unit operates nor-mally. When this parameter is set to “Yes” normal control of the control outputs is overridden and the condition of each

output is defined by setting the remaining items within the Manual Control menu.

Discharge Fan. Discharge Fan= is an adjustable item used to manually turn the discharge air fan on and off.

RF/EF Fan. RF/EF Fan= is an adjustable item used to manually turn the return air or exhaust fan on and off.

Fan Operation. Fan Operation= is an adjustable item used to manually turn the Fan Operation Output (MCB-BO3) on and off.

Alarm. Alarm= is an adjustable item used to manually turn the Remote Alarm Output (MCB-BO4) on and off.

OA Damper. OA Damper= is an adjustable item used to manually drive the outdoor air dampers open and closed.

Mod Cooling. Mod Cooling= is an adjustable item used to manually drive the modulating cooling valve open and closed.

Mod Heating. Mod Heating= is an adjustable item used to manually drive the modulating heating valve open and closed.

RF/EF Vanes. RF/EF Vanes= is an adjustable item used to manually drive the return air or exhaust fan inlet vanes open and closed.

RF/EF VFD. RF/EF VFD= is an adjustable item used to manually increase and decrease the return air or exhaust fan VFD speed.Alarm Out FaultsThe Alarm Out Faults menu contains parameters for deter-mining the action of the Remote Alarm Output (MCB-BO4) when “fault” alarms occur. The Remote Alarm Output is on continuously when there are no active alarms within the con-troller. Each alarm can be set up to cause the Remote Alarm Output to turn off, blink quickly, blink slowly or remain on continuously when the alarm occurs. For detailed informa-tion on configuring the Remote Alarm Output, refer to “Con-figuring Remote Alarm Output” on page 57.

Freeze. Freeze= is an adjustable item used to determine the action of the Remote Alarm Output when the Freeze fault occurs.

Smoke. Smoke= is an adjustable item used to determine the action of the Remote Alarm Output when the Smoke fault occurs.

Space Sensor. Space Sensor= is an adjustable item used to determine the action of the Remote Alarm Output when the Space Sensor fault occurs.

Return Sensor. Return Sensor= is an adjustable item used to determine the action of the Remote Alarm Output when the Return Sensor fault occurs.

Disch Sensor. Disch Sensor= is an adjustable item used to determine the action of the Remote Alarm Output when the Disch Sensor fault occurs.

McQuay OM 138-3 33

Hi Return Tmp. Hi Return Tmp= is an adjustable item used to determine the action of the Remote Alarm Output when the Hi Return Tmp fault occurs.

Hi Disch Tmp. Hi Disch Tmp= is an adjustable item used to determine the action of the Remote Alarm Output when the Hi Disch Tmp fault occurs.

Lo Disch Tmp. Lo Disch Tmp= is an adjustable item used to determine the action of the Remote Alarm Output when the Lo Disch Tmp fault occurs.

Fan Fail. Fan Fail= is an adjustable item used to determine the action of the Remote Alarm Output when the Fan Fail fault occurs.

OA Dmpr Stuck. OA Dmpr Stuck= is an adjustable item used to determine the action of the Remote Alarm Output when the OA Dmpr Stuck fault occurs.Alarm Out ProblemsThe Alarm Out Problems menu contains parameters for determining the action of the Remote Alarm Output (MCB-BO4) when “problem” alarms occur. The Remote Alarm Output is on continuously when there are no active alarms within the controller. Each alarm can be set up to cause the Remote Alarm Output to turn off, blink quickly, blink slowly or remain on continuously when the alarm occurs. For detailed information regarding configuring the Remote Alarm Output, refer to “Configuring Remote Alarm Output” on page 57.

Freeze. Freeze= is an adjustable item used to determine the action of the Remote Alarm Output when the Freeze prob-lem occurs.

OAT Sensor. OAT Sensor= is an adjustable item used to determine the action of the Remote Alarm Output when the OAT Sensor problem occurs.

Space Sensor. Space Sensor= is an adjustable item used to determine the action of the Remote Alarm Output when the Space Sensor problem occurs.

Return Sensor. Return Sensor= is an adjustable item used to determine the action of the Remote Alarm Output when the Return Sensor problem occurs.

Ent Fan Sens. Ent Fan Sens= is an adjustable item used to determine the action of the Remote Alarm Output when the Ent Fan Sens problem occurs.

Low Airflow. Low Airflow= is an adjustable item used to determine the action of the Remote Alarm Output when the Low Airflow problem occurs.

Heat Fail. Heat Fail= is an adjustable item used to deter-mine the action of the Remote Alarm Output when the Heat Fail problem occurs.

Hi Pres-Ckt1. Hi Pres-Ckt1= is an adjustable item used to determine the action of the Remote Alarm Output when the Hi Pres-Ckt1 problem occurs.

Hi Pres-Ckt2. Hi Pres-Ckt2= is an adjustable item used to determine the action of the Remote Alarm Output when the Hi Pres-Ckt2 problem occurs.

Lo Pres-Ckt1. Lo Pres-Ckt1= is an adjustable item used to determine the action of the Remote Alarm Output when the Lo Pres-Ckt1 problem occurs.

Lo Pres-Ckt2. Lo Pres-Ckt2= is an adjustable item used to determine the action of the Remote Alarm Output when the Lo Pres-Ckt2 problem occurs.

Frost-Ckt1. Frost-Ckt1= is an adjustable item used to determine the action of the Remote Alarm Output when the Frost-Ckt1 problem occurs.

Frost-Ckt2. Frost-Ckt2= is an adjustable item used to determine the action of the Remote Alarm Output when the Frost-Ckt2 problem occurs.

Comp #1 Alm. Comp #1 Alm= is an adjustable item used to determine the action of the Remote Alarm Output when the Comp #1 Alm problem occurs.






Ckt1 Clg Ena. Ckt1 Clg Ena= is an adjustable item used to determine the action of the Remote Alarm Output when the Ckt1 Clg Ena problem occurs.

Ckt2 Clg Ena. Ckt2 Clg Ena= is an adjustable item used to determine the action of the Remote Alarm Output when the Ckt2 Clg Ena problem occurs.

GenC Clg Ena. GenC Clg Ena= is an adjustable item used to determine the action of the Remote Alarm Output when the GenC Clg Ena problem occurs.

HtgB Htg Ena. HtgB Htg Ena= is an adjustable item used to determine the action of the Remote Alarm Output when the HtgB Htg Ena problem occurs.

Ckt1 Comm Fail. Ckt1 Comm Fail= is an adjustable item used to determine the action of the Remote Alarm Output when the Ckt1 Comm Fail problem occurs.

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Ckt2 Comm Fail. Ckt2 Comm Fail= is an adjustable item used to determine the action of the Remote Alarm Output when the Ckt2 Comm Fail problem occurs.

GenC Comm Fail. GenC Comm Fail= is an adjustable item used to determine the action of the Remote Alarm Out-put when the GenC Comm Fail problem occurs.

HtgB Comm Fail. HtgB Comm Fail= is an adjustable item used to determine the action of the Remote Alarm Output when the HtgB Comm Fail problem occurs.

ERecB Comm Fail. ERecB Comm Fail= is an adjustable item used to determine the action of the Remote Alarm Out-put when the ERecB Comm Fail problem occurs.Alarm Out WarningsThe Alarm Out Warnings menu contains parameters for determining the action of the Remote Alarm Output (MCB-BO4) when “warning” alarms occur. The Remote Alarm Output is on continuously when there are no active alarms within the controller. Each alarm can be set up to cause the Remote Alarm Output to turn off, blink quickly, blink slowly or remain on continuously when the alarm occurs. For detailed information regarding configuring the Remote Alarm Output, refer to “Configuring Remote Alarm Output” on page 57.

PumpDown-Ckt1. PumpDown-Ckt1= is an adjustable item used to determine the action of the Remote Alarm Out-put when the PumpDown-Ckt1 problem occurs.

PumpDown-Ckt2. PumpDown-Ckt2= is an adjustable item used to determine the action of the Remote Alarm Out-put when the PumpDown-Ckt2 problem occurs.

Airflow Switch. Airflow Switch= is an adjustable item used to determine the action of the Remote Alarm Output when the Airflow Switch warning occurs.

Dirty Filter. Dirty Filter= is an adjustable item used to determine the action of the Remote Alarm Output when the Dirty Filter warning occurs.

Dirty FnlFltr. Dirty FnlFltr= is an adjustable item used to determine the action of the Remote Alarm Output when the Dirty FnlFltr warning occurs.Alarm LimitsThe Alarm Limits menu contains parameters for setting three miscellaneous temperature alarm limits.

Hi Disch Alm. Hi Disch Alm= is an adjustable item which sets a high discharge air temperature alarm limit. If the dis-charge air temperature input exceeds this setting, the unit shuts down completely on the Hi Disch Tmp fault.

Lo Disch Alm. Lo Disch Alm= is an adjustable item which sets a low discharge air temperature alarm limit. If the dis-charge air temperature input falls below this setting while mechanical cooling is not operating, the unit shuts down completely on the Lo Disch Tmp fault.

Hi Return Alm. Hi Return Alm= is an adjustable item which sets a high return air temperature alarm limit. If the return air temperature input exceeds this setting, the unit shuts down completely on the Hi Return Tmp fault.

McQuay OM 138-3 35

Table 7: Setup/Services Menus


Unit Configuration

AHU ID - - xxxxxxxxxxCCB1 ID - - xxxxCCB 2 ID - - xxxxGCB1 ID - - xxxxEHB1 ID - - xxxxERB1 ID - - xxxx

Calibrate Mode No 1NoYes

Space Sensor Yes 1NoYes

EFT Sensor No 1NoYes

2nd P Sensor None 1NoneDuctBldg

RF/EF Ctrl Tracking 1

NoneTrackingBldgPresPosition

Rem RF/EF Cap 25% 1 0-100%

Eng Units EnglishEnglish

SI CanadaSI Europe

Configuration Code

Pos # 1-4 - - 0.000-3.388Pos # 5-8 - - 0.000-1.934

Pos # 9-12 - - 0.000-7.810Pos # 13-16 - - 0.000-9.243Pos # 17-20 - - 0.000-2.121Pos # 21-22 - - 0.0-2.1

Passwords

Timeout 15 min 1 2-60 min

Clear Alarm None 1NoneLvl-1Lvl-2

Operating Hours

Fan 0 1 0-65535 hrMech Cool 0 1 0-65535 hr

Comp 1 0 1 0-65535 hrComp 2 0 1 0-65535 hrComp 3 0 1 0-65535 hrComp 4 0 1 0-65535 hrComp 5 0 1 0-65535 hrComp 6 0 1 0-65535 hrHeating 0 1 0-65535 hr

Economizer 0 1 0-65535 hrTnt Ovrd 0 1 0-65535 hr

Dehumidify 0 1 0-65535 hrERecovery 0 1 0-65535 hr

36 McQuay OM 138-3

Timer Settings

Service 0 min 1 0 - 240 minRecirculate 3 min 1 2 - 60 minLow DAT 3 min 1 2 - 60 min

Max MWU 90 min 1 0 - 240 minInt Ovrd 120 min 1 0 - 300 minStart Init 180 sec 1 0 - 240 sec

Time/Date

Timehh 1 00 - 23

mm 2 00 -59ss 3 00 - 59

Day - - Mon - Sun

Datedt 1 01-31

mon 2 Jan - Decyear 3 1999-2155

Bldg Static P Setup

BSP Propbd 1.0“ WC 1 0.1-30.0“ WCBSP IntTime 10 sec 1 0-3600 secBSP Period 5 sec 1 1-3600 sec

PRAC No 1NoYes

Exhaust Fan Setup

Min Exh Fan Cap 25% 1 1 - 99%Min OA Dmpr Pos 5% 1 1 - 99%

Min DF Cap 10% 1 1 - 99%Min Strt Time 120 sec 1 10 - 240 secMin Stop Time 120 sec 1 10 - 240 sec

Zone Temp Setup

Spt Source Keypad 1Keypad

TstatClg Propbd 8.0°F 1 1.0-99.0°FHtg Propbd 12.0°F 1 1.0 99.0°FClg IntTime 700 sec 1 0-3600 secHtg IntTime 500 sec 1 0-3600 sec

Period 60 sec 1 1-3600 sec

Compressor Setup

Lead Circuit #1 1Auto#1#2

CompCtrl Cross Circ 1Cross CircLead Load

Cond Fan1 Spt 0°F 1 0-105°FCond Fan2 Spt 55°F* 1 0-105°FCond Fan3 Spt 65°F* 1 0-105°FCond Fan4 Spt 75°F* 1 0-105°FCond Fan Diff 5°F 1 5-20°F

Stage Time 5 min 1 5-60 min

Chilled Water Setup

Clg Propbd 30°F 1 1-100°FClg IntTime 60 sec 1 0-3600 secClg Period 30 sec 1 1-3600 sec

PRAC No 1NoYes


Feedback 3 Wire 13 Wire2 Wire

* Varies according to unit model - Refer to Table and Table on page 79.

Table 7: Setup/Services Menus (Continued)


McQuay OM 138-3 37

Economizer Setup

Clg Propbd 30°F 1 1-100°FClg IntTime 60 sec 1 0-3600 secClg Period 30 sec 1 1-3600 sec

PRAC Yes 1NoYes


DesignFlow Setup

Wait Time 30 sec 1 0-180 secModband 50% 1 10-100%Max Step 5.0% 1 0.1-9.9%

DeadBand 6.0% 1 0.1-9.9%LH Lvl Pos - 1 0.00-100.00%RH Lvl Pos - 1 0.00-100.00%

AI11 Reference No 1NoYes

Heating Setup


F&BP Ctrl OpenValve 1OpenValveMod Valve

F&BP Chgovr 37°F 1 0-60°FHtg Propbd 20°F 1 1-100°FHtg IntTime 120 sec 1 0-3600 secHtg Period 60 sec 1 1-3600 sec

PRAC No 1NoYes


Gas Act High 2.90V 1 2.00-3.50V

Energy Rec Setup

Min Exh T 2°F 1 1-10°FMax Exh T 6°F 1 1-20°FStage Time 5 min 1 1-100 min

Min Off Time 20 min 1 1-100 minMin Exh On 120 Sec 1 60-300 SecMin Exh Off 120 Sec 1 60-300 Sec

Dehum Setup

Dehum Ctrl Occupied 1OccupiedAlways

Minimum Stages 2 1 1-8Maximum Stages 4 1 1-8DH Stage Time 10 min 1 3-60 min

Sensor Loc Return 1ReturnSpace



38 McQuay OM 138-3

Manual Control

Manual Control No 1NoYes

Discharge Fan Off 1OnOff

RF/EF Fan Off 1OnOff

Fan Operation Off 1OnOff

Alarm Normal 1Alarm

Normal

OA Damper Auto 1CloseAutoOpen

Mod Cooling Auto 1CloseAutoOpen

Mod Heating Auto 1CloseAutoOpen

RF/EF Vanes Auto 1CloseAutoOpen

RF/EF VFD Auto 1SlowerAuto

Faster

Alarm Out Faults

Freeze Fast 1

OnOff

FastSlow

Smoke Fast 1 Same As FreezeSpace Sensor Fast 1 Same As FreezeReturn Sensor Fast 1 Same As FreezeDisch Sensor Fast 1 Same As Freeze

Hi Return Tmp Fast 1 Same As FreezeHi Disch Tmp Fast 1 Same As FreezeLo Disch Tmp Fast 1 Same As Freeze

Fan Fail Fast 1 Same As FreezeOA Dmpr Stuck Fast 1 Same As Freeze



McQuay OM 138-3 39

Alarm Out Problems

Freeze Slow 1

OnOff

FastSlow

OAT Sensor Slow 1 Same As FreezeSpace Sensor Slow 1 Same As FreezeReturn Sensor Slow 1 Same As FreezeEnt Fan Sens Slow 1 Same As Freeze

Lo Airflow Slow 1 Same As FreezeHeat Fail Slow 1 Same As Freeze

Hi Pres-Ckt1 Slow 1 Same As FreezeHi Pres-Ckt2 Slow 1 Same As FreezeLo Pres-Ckt1 Slow 1 Same As FreezeLo Pres-Ckt2 Slow 1 Same As Freeze

Frost-Ckt1 Slow 1 Same As FreezeFrost-Ckt2 Slow 1 Same As Freeze

Comp #1 Alm Slow 1 Same As FreezeComp #2 Alm Slow 1 Same As FreezeComp #3 Alm Slow 1 Same As FreezeComp #4 Alm Slow 1 Same As FreezeComp #5 Alm Slow 1 Same As FreezeComp #6 Alm Slow 1 Same As FreezeCkt1 Clg Ena Slow 1 Same As FreezeCkt2 Clg Ena Slow 1 Same As Freeze

GenC Clg Ena Slow 1 Same As FreezeHtgB Htg Ena Slow 1 Same As Freeze

Ckt1 Comm Fail Slow 1 Same As FreezeCkt2 Comm Fail Slow 1 Same As Freeze

GenC Comm Fail Slow 1 Same As FreezeHtgB Comm Fail Slow 1 Same As Freeze

ERecB Comm Fail Slow 1 Same As Freeze

Alarm Out Warnings

Pump Down-Ckt1 Off 1

OnOff

FastSlow

Pump Down-Ckt2 Off 1 Same as Pump Down-Ckt1

Aiflow Switch Off 1 Same As Pump Down-Ckt1

Dirty Filter Off 1 Same As Pump Down-Ckt1

Dirty FnlFltr Off 1 Same As Pump Down-Ckt1

Alarm LimitsHi Discharge Alm 170°F 1 90 - 250°FLo Discharge Alm 40°F 1 20 - 50°F

Hi Return Alm 120°F 1 90 - 150°F



40 McQuay OM 138-3

Active AlarmsMenus in the Active Alarms category contain alarm informa-tion for up to 4 active alarms. Table 8 on page 42 lists all menus and items in the Active Alarms group or category. The “Range” column in the table lists all possible values for each item. The factory settings for the adjustable parameters are shown in the “Factory Default Value” column. The fol-lowing are brief descriptions of the Active Alarms category menus and items. For detailed information regarding alarm handling, refer to “Alarm Monitoring” on page 53 and “Alarm Control” on page 98.Active Alarm 1The Active Alarm 1 menu provides details regarding the highest priority active alarm.

Alarm Name. Alarm Name= is a status only item that iden-tifies the name of Active Alarm 1.

Alarm Type. Alarm Type= is a status only item that identi-fies the alarm type (fault, problem or warning) of Active Alarm 1.

Alarm Date and Time. This is a status only item that indi-cates the date and time of occurrence of Active Alarm 1.Active Alarm 2The Active Alarm 2 menu provides details regarding the sec-ond highest priority active alarm.



Alarm Date and Time. This is a status only item that indi-cates the date and time of occurrence of Active Alarm 2.Active Alarm 3The Active Alarm 3 menu provides details regarding the third highest priority active alarm.



Alarm Date and Time. This is a status only item that indi-cates the date and time of occurrence of Active Alarm 3.Active Alarm 4The Active Alarm 4 menu provides details regarding the fourth highest priority active alarm.



Alarm Date and Time. This is a status only item that indi-cates the date and time of occurrence of Active Alarm 4.

McQuay OM 138-3 41

Table 8: Active Alarm Menus


Active Alarm 1

Alarm Name - -

NoneFreeze (Fault)Smoke (Fault)

Space Sensor (Fault)Return Sensor (Fault)Disch Sensor (Fault)

Hi Return Tmp (Fault)Hi Disch Tmp (Fault)Lo Disch Tmp (Fault)

Fan Fail (Fault)OA Dmpr Stuck (Fault)

Freeze (Problem)OAT Sensor (Problem)

Space Sensor (Problem)Return Sensor (Problem)Ent Fan Sens (Problem)

Lo Airflow (Problem)Heat Fail (Problem)

Hi Pres-Ckt1 (Problem)Hi Pres-Ckt2 (Problem)Lo Pres-Ckt1 (Problem)Lo Pres-Ckt2 (Problem)

Frost-Ckt1 (Problem)Frost-Ckt2 (Problem)

Comp #1 Alm (Problem)Comp #2 Alm (Problem)Comp #3 Alm (Problem)Comp #4 Alm (Problem)Comp #5 Alm (Problem)Comp #6 Alm (Problem)Ckt1 Clg Ena (Problem)Ckt2 Clg Ena (Problem)

GenC Clg Ena (Problem)HtgB Htg Ena (Problem)

Ckt1 Comm Fail (Problem)Ckt2 Comm Fail (Problem)

GenC Comm Fail (Problem)HtgB Comm Fail (Problem)

ERecB Comm Fail (Problem)PumpDown-Ckt1 (Warning) PumpDown-Ckt2 (Warning)

Airflow Switch (Warning)Dirty Filter (Warning)Drty FnlFltr (Warning)

Alarm Type - -

-Fault-Active

Problem-ActiveWarning-Active

Alarm Date and Time - - dd-mmm-yy/hh:mm:ss

Active Alarm 2

Alarm Name - - Same As Active Alm 1

Alarm Type - -

-Fault-Active

Problem- ActiveWarning- Active


42 McQuay OM 138-3

Previous AlarmsMenus in the Previous Alarms category contain alarm infor-mation for up to 8 previous alarms. Table 9 lists all menus and items in the Previous Alarms group or category. The “Range” column in the table lists all possible values for each item. The factory settings for the adjustable parameters are shown in the “Factory Default Value” column. The follow-ing are brief descriptions of the Previous Alarms category menus and items. For detailed information regarding alarm handling, refer to “Alarm Monitoring” on page 53 and “Alarm Control” on page 98.Previous Alarm 1The Previous Alarm 1 menu provides details regarding the most recently cleared previous alarm.

Alarm Name. Alarm Name= is a status only item that iden-tifies the name of Previous Alarm 1.

Alarm Type. Alarm Type= is a status only item that identi-fies the alarm type (fault, problem or warning) of Previous Alarm 1.

Alarm Date and Time. This is a status only item that indi-cates the date and time of occurrence of Previous Alarm 1.Previous Alarm 2 through Previous Alarm 8The Previous Alarm 2 through the Previous Alarm 8 menus provide details regarding the second through eighth most recently cleared previous alarm. The description of these menus is identical to Previous Alarm 1.

Active Alarm 3


Alarm Type - -

-Fault- Active



Active Alarm 4


Alarm Type - -

-Fault- Active



Table 8: Active Alarm Menus (Continued)


Table 9: Previous Alarm Menus


Previous Alarm 1


Alarm Type - -

-

Fault- Clear

Problem- Clear

Warning- Clear

Alarm Date and Time - dd-mmm-yy/hh:mm:ss

Previous Alarm 2


Alarm Type - - Same As Previous Alm 1


Previous Alarm 3




Previous Alarm 4




Previous Alarm 5




McQuay OM 138-3 43

Remote Keypad Display OptionA unit may be equipped with a remote keypad/display option. When this is the case either the local unit keypad/dis-play or the remote keypad/display is active. When the selec-tor switch on the remote keypad/display control board in the unit is switched to the “local” setting, the local keypad/dis-play is active and the remote keypad/display is disabled (the “local” LED on the board is ON and the “remote” LED on the board is OFF). When the selector switch is switched to the “remote “setting, the remote keypad/display is active and the local keypad/display is disabled (the “local” LED on the board is OFF and the “remote” LED on the board is ON). Note: When the selector switch position is changed, the selected keypad/display goes through the “normal” power up sequence before becoming active. This generally takes about 60 seconds.The operation of the remote keypad is identical to that of the local keypad/display as described in the previous sections.

Previous Alarm 6




Previous Alarm 7




Previous Alarm 8




Table 9: Previous Alarm Menus (Continued)


CAUTIONUnit can be started from a remote location. Injury to others can occur.

When the remote keypad is enabled, the potential exits for the unit to be started from a remote location. Make sure the keypad/display selector switch is in the "local" position ("local" LED on the remote key-pad/display control board is ON and the "remote" LED is OFF) or that remote keypad is physically discon-nected before servicing the unit. If the local unit keypad/display is blank, it is most likely that the remote keypad display is active.

44 McQuay OM 138-3

Operator’s GuideThe following “Operator’s Guide” sections provide informa-tion regarding the day-to-day operation of the MicroTech II Applied Rooftop Unit Controller. Topics covered are such common tasks as scheduling, displaying and clearing alarms, and setting the controller for manual operation. Programma-ble parameters that affect the operation being described are listed at the beginning of each applicable sub-section. The factory default values for these parameters are shown in italic letters.For detailed information regarding the control processes and their programmable parameters, refer to “Description of Operation” on page 63.

Determining Unit StatusThe System menu includes several parameters that can be used to determine the overall status of the unit. There are five key items in this menu that summarize the current oper-ating condition of the unit. These are: UnitStatus=, Clg Capacity=, Htg Capacity=, Clg Status=, and Htg Status= and are described in the following sections.

UnitStatusThe UnitStatus= parameter in the System menu is very use-ful because the item summarizes the overall operating condi-tion of the unit. Each of the possible conditions is referred to as an “operating state”. The following are the possible oper-ating states displayed by the UnitStatus= parameter.

• Off• Calib• Startup • Recirc• Fan Only• Econo• Cooling• MWU• Heating• Min DAT• UnocEcon• UnocClg• UnocHtg• Man Ctrl

The unit makes transitions between these operating states as conditions change. For detailed information regarding these states, refer to “Operating States and Sequences” on page 63.

Clg CapacityClg Capacity= is a status item which indicates the percent-age of the unit maximum cooling capacity currently operat-

ing. When the unit is equipped with chilled water cooling, 0-100% is displayed as the cooling valve actuator strokes from the closed to open position. When the unit is equipped with compressorized cooling, the percentage value changes incre-mentally based on the number operating cooling stages.

Htg CapacityHtg Capacity= is a status item which indicates the percent-age of the unit maximum heating capacity currently operat-ing. When the unit is equipped with modulating heat, 0-100% is displayed as the heating valve actuator strokes from the closed to open position. When the unit is equipped with staged heat, the percentage value changes incrementally based on the number operating heating stages

Clg StatusClg Status= is a status item which indicates whether or not cooling (economizer and/or mechanical) is currently allowed. If cooling is disabled, the reason is indicated. The following are descriptions of the various “Clg Status” states.All ClgThe Clg Status= parameter indicates “All Clg” when both of the following conditions are true:1. The unit is equipped with an economizer and the out-

door air is suitable for free cooling (OA Ambient= parameter in the OA Damper menu indicates “Low”).

2. The outdoor air is warm enough to allow mechanical cooling operation (OA Temp= parameter in the Temper-atures menu has risen above the OATComp Lock= parameter by more that the OATLock Diff= setting in the Zone Cooling menu).

In this state the unit uses the economizer, mechanical cooling or both as required to maintain the cooling set points.EconoThe Clg Status= parameter indicates “Econo” when both of the following conditions are true:1. The unit is equipped with an economizer and the out-

door air is suitable for free cooling (OA Ambient= parameter in the OA Damper menu indicates “Low”).

2. The outdoor air is too cool to allow mechanical cooling operation (OA Temp= parameter in the Temperatures menu has dropped below the OATComp Lock= setting in the Zone Cooling menu).

In this state the unit only uses the economizer to maintain the cooling set points. Mechanical cooling operation is disabled.

McQuay OM 138-3 45

Mech ClgThe Clg Status= parameter indicates “Mech Clg” when both of the following conditions are true:1. The unit is not equipped with an economizer or the out-

door air is not suitable for free cooling (OA Ambient= parameter in the OA Damper menu indicates “High”).

2. The outdoor air is warm enough to allow mechanical cooling operation (OA Temp= parameter in the Temper-atures menu has risen above the OATComp Lock= parameter by more that the OATLock Diff= setting in the Zone Cooling menu).

In this state the unit uses mechanical cooling to maintain the cooling set points. Economizer operation is disabled, and the outdoor air damper is maintained at the Eff Min OA Pos= value.Off AmbThe Clg Status= parameter indicates “Off Amb” when both of the following conditions are true:1. The unit is not equipped with an economizer or outdoor

air is not suitable for free cooling (OA Ambient= param-eter in the OA Damper menu indicates “High”).

2. The outdoor air is too cool to allow mechanical cooling operation (OA Temp= in the Temperatures menu has dropped below the OATComp Lock= setting in the Zone Cooling menu).

In this state both economizer and mechanical cooling opera-tion is disabled.For applications that use an economizer, the “Off Amb” state should not occur if the economizer changeover and mechani-cal cooling lockout set points are adjusted properly. If it does occur, it may indicate a problem with the enthalpy sensing device.Off AlmThe Clg Status= parameter indicates “Off Alm” when cool-ing related alarms cause all cooling circuits to be completely disabled and economizer operation is not available. For detailed information regarding cooling alarms and their effect on the unit operation, Refer to “Alarm Control” on page 98. All cooling is disabled during the “Off Alm” state.Off SwThe Clg Status= parameter indicates “Off Sw” when the field cooling enable terminals 101 to 105 on terminal block TB2 in the main control panel are not made (binary input MCB-BI3 is off). Refer to the “Manual Cooling and Heating Enable/Disable” section of IM 696, MicroTech Applied Roof-top Unit Controller. All cooling is disabled during the “Off Sw” state.Off ManThe Clg Status= parameter indicates “Off Man” when cool-ing is disabled via the Ctrl Mode= parameter in the System menu. This occurs when the Ctrl Mode= parameter is set to either “Heat Only” or “Fan Only.” All cooling is disabled during the “Off Man” state.

Off NetThe Clg Status= parameter indicates “Off Net” when cooling is disabled by a network signal affecting the Appl Mode= parameter in the System menu. This is the case when the Appl Mode= parameter is set to either “Heat Only” or “Fan Only.” All cooling is disabled during the “Off Net” state.Off NoneThe Clg Status= parameter indicates “Off None” when the unit is equipped with no cooling of any kind.

Htg StatusHtg Status= is a status item which indicates whether or not heating is currently allowed. If heating is disabled, the rea-son is indicated. The following are descriptions of the vari-ous “Htg Status” states.Htg EnaThe Htg Status= parameter indicates “Htg Ena” when the unit is equipped with some kind of heating and the outdoor air is cool enough to allow heating operation and heat is not disabled for some other reason. (OA Temp= parameter in the Temperatures menu has dropped below the OATHtg Lock= parameter by more that the OATLock Diff= setting in the Zone Heating menu). In this state the unit uses the heat as required to maintain the heating set points.Off AmbThe Htg Status= parameter indicates “Off Amb” when the unit is equipped with heat and the outdoor air is too warm to allow heating operation (OA Temp= parameter in the Tem-peratures menu has risen above the OATHtg Lock= setting in the Zone Heating menu). In this state heating operation is disabled.Off AlmThe Htg Status= parameter indicates “Off Alm” when heat-ing related alarms cause all heating to be completely dis-abled. For detailed information regarding heating alarms and their effect on the unit operation, refer to “Alarm Control” on page 98. All heating is disabled during the “Off Alm” state.Off SwThe Htg Status= parameter indicates “Off Sw” when the field heating enable terminals 101 to 106 on terminal block TB2 in the main control panel are not made (binary input MCB-BI4 off). Refer to the “Manual Cooling and Heating Enable/Disable” section of IM 696, MicroTech Applied Roof-top Unit Controller. Heating is disabled during the “Off Sw” state.Off ManThe Htg Status= parameter indicates “Off Man” when heat-ing is disabled via the Ctrl Mode= parameter in the System menu. This occurs when the Ctrl Mode= parameter is set to either “Cool Only” or “Fan Only.” Heating is disabled dur-ing the “Off Man” state.

46 McQuay OM 138-3

Off NetThe Htg Status= parameter indicates “Off Net” when heating is disabled by a network signal affecting the Appl Mode= parameter in the System menu. This occurs when the Appl Mode= parameter is set to either “Cool Only” or “Fan Only.” Heating is disabled during the “Off Net” state.Off NoneThe Htg Status= parameter indicates “Off None” when the unit is equipped with no heating.

Auto/Manual OperationThe System menus includes two parameters that determine whether cooling, heating, both cooling and heating or neither are enabled during unit operation. These are the Ctrl Mode= and Appl Mode= parameters. The Occupancy menu includes five parameters that relate to the occupied/unoccupied condi-tion (start/stop) of the unit. These are the Occupancy=, Occ Mode=, Occ Src=, Bypass Time=, and Emerg Override= parameters. These are described in the following sections.

Ctrl Mode

The unit cooling and heating can be set up for automatic heat/cool, cool only, heat only, fan only, or network cool/heat operation by setting the Control Mode. The unit can also be manually disabled via the Control Mode. The following are descriptions of the six available Control Mode selections.OffWhen the Control Mode is set to “Off”, the UnitStatus= is “Off Man” and the unit is completely disabled.Heat CoolWhen the Control Mode is set to “Heat/Cool”, both cooling and heating operation are allowed to operate as required to maintain the cooling and heating set points.

Cool OnlyWhen the Control Mode is set to “Cool Only”, cooling oper-ation is allowed to operate to maintain the cooling set points. Heating operation is disabled (Htg Status= is “Off Man”).Heat OnlyWhen the Control Mode is set to “Heat Only”, heating oper-ation is allowed to operate to maintain the heating set points. Cooling operation is disabled (Clg Status= is “Off Man”).Fan OnlyWhen the Control Mode is set to “Fan Only”, the fans are allowed to operate but cooling and heating operation is dis-abled (Clg Status= and Htg Status= are “Off Man”).AutoWhen the Control Mode is set to “Auto”, the heat/cool, cool only, heat only, and fan only decision is determined by the Appl Mode= parameter, which is set via a network signal as described below. The Appl Mode= parameter has no effect on unit operation unless the Control Mode is set to “Auto.”

Appl Mode

The unit heating and cooling can be set up for automatic heat/cool, heat only, cool only or fan only operation based on a network signal by setting the Ctrl Mode= parameter to “Auto.” With the Ctrl Mode= parameter set to “Auto”, the heat/cool, cool only, heat only, and fan only decision is deter-mined by the Application Mode. The Application Mode is set by a network signal. The following sections describe the five available Application Mode selections.

Note: The Application Mode has no effect on the unit operation unless the Ctrl Mode= parameter is set to “Auto.”

OffWhen the Application Mode is set to “Off”, the UnitStatus= is “Off Net” and the unit is completely disabled, including unoccupied heating (night set back) and unoccupied cooling (night set up) operation.

WARNINGElectric shock and moving machinery hazard. Can cause personal injury or death.

When the unit is in any Off operating state, power is not removed from the unit controller or components. Remove power by turning off the disconnect-switch before servicing line voltage equipment or entering the unit.

Table 10: Programmable Parameters

Keypad/Display IDParameter Name

Menu Name Item Name

System Ctrl Mode= Off Control Mode



Menu Name Item Name

System Appl Mode= Heat/Cool Application Mode

McQuay OM 138-3 47

Heat/CoolWhen the Application Mode is set to “Heat/Cool”, both cooling and heating operation are allowed to operate as required to maintain the cooling and heating set points.Cool OnlyWhen the Application Mode is set to “Cool Only”, cooling operation is allowed to operate as required to maintain the cooling set points. Heating operation is disabled (Htg Sta-tus= is “Off Net”).Heat OnlyWhen the Application Mode is set to “Heat Only”, heating operation is allowed to operate as required to maintain the heating set points. Cooling operation is disabled (Clg Sta-tus= is “Off Net”).Fan OnlyWhen the Application Mode is set to “Fan Only”, the fans are allowed to operate but cooling and heating operation is disabled (Clg Status= and Htg Status= are “Off Net”).

OccupancyOccupancy= is a status item which indicates whether the unit is in an occupied or unoccupied mode of operation. The following are descriptions of the various “Occupancy” states.OccThe Occupancy= parameter indicates “Occ” when the unit is in the occupied mode. In this mode, the unit generally starts and runs continuously, cooling and heating as required to maintain the occupied temperature set points.1 The unit is in the occupied mode if any of the following conditions are true:1. The Occ Mode= parameter is set to “Occ.”2. The Occ Mode= parameter is set to “Auto” and a field

supplied external time clock or a tenant override switch signal in the form of a set of dry contacts is closed across terminals 101 and 102 on the unit field terminal block TB2 (binary input MCB-BI1 on). Note: Placing the unit S7 switch into the “On” position makes terminals 101 to 102 on TB2.For detailed information refer to “External Time Clock or Tenant Override (Non-Timed)” in IM 696, MicroTech II Applied Rooftop Unit Controller.

3. The Occ Mode= parameter is set to “Auto” and the unit internal time clock schedule, optimal start function, one time event schedule, or an optional network schedule indicates an occupied period.

UnoccThe Occupancy= parameter indicates “Unocc” when the unit is in the unoccupied mode. In the unoccupied mode, the unit is off and remains off unless unoccupied cooling (night set up or purge) or unoccupied heating (night set back) opera-tion is activated. Refer to “Propeller Exhaust Fan Control” on page 95. The unit is in the unoccupied mode if the Occ Mode= parameter is set to “Unocc” or to “Auto” and none of the three items listed above in the “Occ” section.

Note: The unit reverts to unoccupied mode if the calibrate function is active. For more information on cali-brate mode, refer to “Calibrate Mode” on page 58.

Tnt OvrdThe Occupancy= parameter indicates “Tnt Ovrd” when the unit is in the tenant override mode. In the tenant override mode the unit starts up and function as it does in occupied mode.1 The unit is in the tenant override mode if the Tnt Ovrd= parameter is set to a non-zero value. For details regarding how the Tnt Ovrd= is set, refer to “Tenant Over-ride” on page 50.

Occ Mode

The unit can be set up for automatic or manual occu-pied/unoccupied operation by setting the Occupancy Mode. The following are descriptions of the four available Occu-pancy Mode selections.AutoWhen the Occupancy Mode is set to “Auto”, the unit oper-ates automatically. This means that the Occupancy= parame-ter changes automatically between “Occ”, Unocc” and “Bypass”. The Occupancy= parameter indicates “Occ” and the unit starts if any of the following are true:1. The current time of day crosses a start time in the inter-

nal time scheduling function.2. The external time clock terminals 101 and 102 on termi-

nal block TB2 are made.Note: The terminals can be made by a field supplied switch or normally open set of contacts or by placing the unit S7 switch in the “On” position. Refer to “External Time Clock or Tenant Override” in IM 696, MicroTech II Applied Rooftop Controller.

3. The unit optimal start function is activated.4. The one time event schedule function is activated.5. A network scheduling function indicates occupied

operation.

1. The unit will not start regardless of the occupancy mode when the UnitStatus= parameter indicates “Off Sw”, “Man Ctrl”, “Off Alm”, “Off Net”, or “Off Man”. For a description of these operating states, refer to “Operating State Descrip-tions” on page 63.



Menu Name Item Name

Occupancy Occ Mode= Auto Occupancy Mode

48 McQuay OM 138-3

The Occupancy= parameter indicates “Unocc” and the unit stops if all of the following are true:1. The current time of day crosses a stop time in the inter-

nal time scheduling function or the time scheduling function has never been activated.

2. The external time clock terminals 101 and 102 on termi-nal block TB2 are not made. Note: The terminals can be made by a field supplied switch or normally open set of contacts or by placing the unit S7 switch in the “On” position. Refer to “External Time Clock or Tenant Over-ride” in IM 696, MicroTech II Applied Rooftop Control-ler.

3. The unit optimal start function is inactive.4. The one time event schedule is inactive.5. Any network scheduling function indicates unoccupied

operation.

Note: The unit can start up and run while the Occupancy= parameter indicates “Unocc” if the unoccupied heating (night set back) or unoccupied cooling (night set up or purge) functions are active. Refer to “Unoccupied Control” on page 96.

Note: The Occupancy= parameter indicates “Unocc” and the unit stops if the Calibrate function is activated. Refer to “Calibrate Mode” on page 58.

The Occupancy= parameter indicates “Tnt Ovrd” and the unit starts if the Tinctured= parameter in the Occupancy menu is set to a non-zero value1. For details regarding how the TntOvrd= parameter is set, refer to “Tenant Override” on page 50.OccWhen the Occupancy Mode is set to “Occ”, the Occupancy= parameter indicates “Occ” and the unit starts and runs con-tinuously in the occupied mode1. Any scheduling commands are prevented from shutting down the unit.The Occupancy= parameter indicates “Unocc” and the unit stops if the Calibrate function is activated. Refer to “Cali-brate Mode” on page 58. UnoccWhen the Occupancy Mode is set to “Unocc”, the Occu-pancy= parameter indicates “Unocc” and the unit is off and remains off unless unoccupied cooling (night set up or purge) or unoccupied heating (night set back) operation is activated. Refer to “Propeller Exhaust Fan Control” on page 951.

Tnt OvrdWhen the Occupancy Mode is set to “Tnt Ovrd”, the TntOvrd= parameter in the Occupancy menu is set to the TntOvrd= value in the Timer Settings menu. The Occu-pancy= parameter indicates “Tnt Ovrd” and the unit starts and operates as in the occupied mode until the Tnt Ovrd= parameter times out. Any scheduling commands are pre-vented from shutting down the unit while the tenant override operation is active.1

Note: Once the Occupancy Mode is set to “Tnt Ovrd” and the TntOvrd= parameter in the Occupancy menu is set to the TntOvrd= value in the Timer Settings menu, the Occupancy Mode automatically reverts to the “Auto” setting.

Note: The Occupancy= parameter indicates “Unocc” and the unit stops if the Calibrate function is activated. Refer to “Calibrate Mode” on page 58.

OccSrcOccSrc= is a status item which indicates the input source or function that is responsible for setting the Occupancy= parameter to “Occ.” There are a number of things that can change the Occupancy= parameter to “Occ” and the Occ Src= parameter is very helpful in determining which func-tion has started the unit.NoneThe Occ Src= parameter indicates “None” when the Occu-pancy= parameter indicates “Unocc” or “Tnt Ovrd.” Int SchedThe Occ Src= parameter indicates “Int Sched” when the Occupancy= parameter indicates “Occ” due to the unit inter-nal schedule or one event schedule indicating an occupied period. Refer to “Scheduling” on page 51.Net SchedThe Occ Src= parameter indicates “Net Sched” when the Occupancy= parameter indicates “Occ” due to a network schedule indicating an occupied period.Occ ModeThe Occ Src= parameter indicates “Occ Mode” when the Occupancy= parameter indicates “Occ” due to the Occu-pancy Mode being manually set to “Occ.”Remote SwThe Occ Src= parameter indicates “Remote Sw” when the Occupancy= parameter indicates “Occ” due to a field sup-plied external time clock or a tenant override switch signal in the form of a set of dry contacts is closed across terminals 101 and 102 on the unit field terminal block TB2 (binary input MCB-BI1 on). For detailed information refer to “External Time Clock or Tenant Override (Non-Timed)” in IM 696, MicroTech II Applied Rooftop Unit Controller.


McQuay OM 138-3 49

Tenant Override

There are two types of tenant override functions: timed and non-timed. Timed override uses the Tenant Override Timer and Tenant Override Time Increment to place the unit into tenant override mode. Non-timed override uses a simple field supplied SPST switch to override unoccupied opera-tion. Timed Tenant OverrideThe tenant-override button provided with the optional zone temperature sensor packages is used to override unoccupied operation for a preprogrammed time period. This time period is set with the Tenant Override Time Increment. This value can be adjusted from 0 to 300 minutes (default is 120 min-utes).When an occupant presses and releases the tenant-override button on the zone temperature sensor (ZNT1), the Tenant Override Timer is set equal to the Tenant Override Time Increment. (The button must be held for at least 1 second but not more than 30 seconds.) The unit then starts and runs in the tenant override mode which is the same as occupied mode except that it is temporary.1 The Tenant Override Timer begins timing out and the unit runs until the timer expires. If the tenant override button is pressed again while the unit is operating in tenant override mode, the Tenant Override Timer is reset to the Tenant Override Time Incre-ment and the unit continues to operate. For example, assume that the Tenant Override Time Increment is 120 minutes. One press of the override button provides at least 120 min-utes of unit operation. If the button is pressed again 60 min-utes later, the Tenant Override Timer is reset to 120 minutes, and a total of 180 minutes of uninterrupted operation results.

Note: The same operation occurs if, instead of pressing the override button on a zone temperature sensor, the Occupancy Mode is set to “Tnt Ovrd.” Once set to “Tnt Ovrd”, the Occupancy Mode automatically

reverts to the “Auto” setting once the Tenant Over-ride Timer is set to the Tenant Override Time Incre-ment.

Non-Timed Tenant OverrideIf an field supplied external time clock or a tenant override switch signal in the form of a set of dry contacts is closed across terminals 101 and 102 on the unit field terminal block TB2 (binary input MCB-BI1 on), the unit is placed into occupied mode1. When this switch is open, the unit is con-trolled by any active scheduling function (internal time clock schedule, optimal start function, one time event schedule, or an optional network schedule). If there is no active schedul-ing function, the unit remains in the unoccupied mode. For detailed information refer to “External Time Clock or Tenant Override (Non-Timed)” in IM 696, MicroTech II Applied Rooftop Unit Controller.Operator OverrideThe Tenant Override Timer can be manually set. When the Tenant Override Timer is set to a non-zero value, the unit starts and runs in the tenant override mode regardless of any scheduling features.1 The unit stops when the timer expires. The Tenant Override Timer can be set from 0-300 minutes.

Note: If the Tenant Override Timer remaining time is larger than the Tenant Override Time Increment, pressing the tenant override button on the space sensor has no effect. If the Tenant Override Timer remaining time is less than the Tenant Override Time Increment, pressing the tenant override button resets the Tenant Override Timer to the Tenant Override Time Increment value.

Emergency Override

The unit can be shutdown by setting the Emergency Over-ride Mode Flag. When the Emergency Override Mode Flag is set to “Off”, the UnitStatus= parameter indicates “Off Net” and the unit remains off regardless of any time schedule or other occupied or unoccupied start commands. The only way a unit can be restarted is to set Emergency Override Mode Flag back to “Norm.” The Emergency Override Mode Flag can either be set manually at the unit keypad or via a network signal.



Menu Name Item Name

OccupancyOcc Mode= Auto Occupancy ModeTnt Ovrd= 0 min Tenant Override Timer

Timer Settings Tnt Ovrd= 120 min Tenant Override Time Increment




Menu Name Item Name

Occupancy Emerg Override= Norm Emergency Override Mode Flag

50 McQuay OM 138-3

SchedulingThe rooftop unit can be scheduled for operation by using the following three methods:1) Unit internal time scheduling functions2) External time clock function3) Network time scheduling functionProvided the unit is not locally or remotely disabled, the unit operates when any of these scheduling functions is calling for occupied operation. Conversely, the unit enters the unoc-cupied mode when all of these scheduling functions are call-ing for unoccupied operation. Therefore, any unused scheduling functions should be set for continuous unoccu-pied operation. Refer also to“Auto/Manual Operation” on page 47.The next four sections: “Setting Controller Date and Time”, “Internal Daily Scheduling”, “Holiday Scheduling”, and One Event Scheduling” describe functions related to the internal unit scheduling functions. These are followed by a section describing the optimal start function which can be use with internal scheduling and network scheduling. This is followed by two sections that describe the external time scheduling and network time scheduling functions.

Setting Controller Date and Time

The MicroTech II controller uses the date and time to exe-cute its internal scheduling functions. Once set, the battery backed internal time clock keeps the current time regardless of whether or not power is being supplied to the unit.

Note: The controller date and time may revert to an archived value if power is interrupted to the con-troller and the controller battery is defective or not installed.

The time of day can be set by entering the hour (00-23), minute (00-59), and second (00-59) into three fields of the Current Time. Note that MicroTech II uses “military” time. The day of the week is not adjustable. The Current Day is set automatically by the controller based on the Current Date. The current date can be set by entering the date (00-31), month (01-12) and year (1999-2155) into the three fields of the Current Date.

Internal Daily Scheduling

When the Occ Mode= parameter, described in “Auto/Man-ual Operation” on page 47, is set to “Auto”, and the unit is not disabled for other reasons, it starts and stops according to the controller internal schedule. One start and one stop time can be set for each day of the week and for designated holi-days. An example of how to use the keypad to enter or mod-ify a schedule is given in “Getting Started” on page 5.As shown in Figure 5, each daily schedule has four adjust-able fields: Start Hour, Start Minute, Stop Hour, and Stop Minute. The schedule shown would cause the unit to start up at 6:30 a.m. and shut down at 6:00 p.m. every Monday, Tues-day and Wednesday.

Figure 5:Daily Schedule Fields

Notes: 1. A unit will start based on a daily schedule only if the

Current Time= value actually crosses a start time for the given day. For example, if the current day start and stop time were set to 06:00 - 18:00 at 10:00 in the morning on that day, the unit would not start because Current Time= value would not cross the 06:00 start time.

2. A unit will stop based on a daily schedule only if the Current Time= value actually crosses a non-zero stop time for the given day. For example, if a unit were run-ning based on a 06:00 - 18:00 schedule on a given day and the stop time for that day were the set to 00:00 before the Current Time= value crossed 18:00, the unit would not stop on that day.

3. For no unit operation for an entire day, the schedule fields for that day should be set to “00:00-00:00”.



Menu Name Item Name

Time/DateTime= hh:mm:ss Current Time

Day= ddd Current DayDate= dd-mm-yyyy Current Date



Menu Name Item Name

Daily Schedule

Mon= 00:00 - 00:00 Monday ScheduleTue= 00:00 - 00:00 Tuesday ScheduleWed= 00:00 - 00:00 Wednesday ScheduleThu= 00:00 - 00:00 Thursday ScheduleFri= 00:00 - 00:00 Friday ScheduleSat= 00:00 - 00:00 Saturday ScheduleSun= 00:00 - 00:00 Sunday ScheduleHol= 00:00 - 00:00 Holiday Schedule

**Edit ModeMon= 06:30 - 18:00Tue= 06:30 - 18:00Wed= 06:30 - 18:00

Menu Line

Item Line Being Edited

Start Hour

Start Minute

Stop Hour

Stop Minute

McQuay OM 138-3 51

4. For continuous unit operation, the start time for the first day of required operation should be set to the desired start time and the stop time for the last day of required operation should be set to the desired stop time. All start and stop times in between should be left at 00:00. For example, if a unit needed to run continuously Monday through Friday and remain off over the weekend, the following schedule settings would be used:Mon = 00:01-00:00Tue = 00:00-00:00Wed = 00:00-00:00Thu = 00:00-00:00Fri = 00:00-23:59Sat = 00:00-00:00Sun = 00:00-00:00 Hol = 00:00-00:00

Holiday Scheduling

Special operating hours can be scheduled for up to 16 holi-day periods during the year by using the holiday scheduling feature. (The wildcard character “*” in the above table could be any number between 1 and 16.) Whenever a holiday period occurs, the controller uses the Holiday Schedule start and stop time for the period. For example, assume that Christmas Eve occurs on a Thursday. The building is shut down on both Christmas Eve and Christmas Day, but oper-ates normally on the weekend. This holiday period would be scheduled by setting the Holiday Schedule to “00:00-00:00” and setting the Holiday Period to “Dec 24 - Dec 25.”If any of the 16 holiday periods are not required, the Holiday Period is set to “N/A - N/A.”

One Event Scheduling

The unit can be scheduled to operate during a specified period by using the one event scheduling feature. During the specified period defined by the One Event Beginning Date/Time and One Event Ending Date/Time parameters the unit starts up and runs continuously regardless of any other time scheduling functions. For example, assume that a space served by the unit is occupied for a special event on March 12 from 5:00 p.m. to 10:00 p.m. when the normal time scheduling has the unit shut off after 4:00 p.m. on that date. This event can be accounted for by setting the One Event Beginning Date/Time to “Mar 12 @ 17:00” and the One Event Ending Date/Time to “Mar 12 @ 22:00.” If a one-event schedule is not required, the One Event Beginning Date/Time and One Event Ending Date/Time parameters are both set to “N/A.”

Optimal StartThe optimal start function can only be used with the unit internal time schedule or a network supplied time schedule that indicates “time-to-occupancy”. When the Optimal Start Flag is set to “Yes”, the controller calculates an early start time before each normally scheduled start. The controller uses the start history, outdoor air temperature, and space temperature to determine when the unit should start when using the unit’s internal time schedule. Alternatively, the unit will start when a network supplied “time to occupancy” parameter is less than the controller’s calculated early start time before occupancy.If the Ctrl Temp= parameter, which is the temperature input selected by the CtrlTemp Src= parameter, is below the Effec-tive Heating Enable Set Point by more than half the Heating Enable Deadband setting, optimal start operation is based on the optimal start heating parameters. If the Ctrl Temp= value is above the Effective Cooling Enable Set Point by more than half Cooling Enable Deadband setting, optimal start operation is based on the optimal start cooling parameters. Unit startup occurs at the scheduled start time if the Ctrl Temp= value is in between these limits.



Menu Name Item Name

Daily Schedule Holiday= 00:00 - 00:00 Holiday ScheduleHoliday Schedule Hol *= mmm dt - mmm dt Holiday Period



Menu Name Item Name

One EventBeg= mmm dd @ hh:mm One Event Beginning

Date/Time

End= mmm dd @ hh:mm One Event Ending Date/Time

52 McQuay OM 138-3

When heating is required, a “heating rate” that varies with the outdoor air temperature is calculated using the formula:

The minutes before occupancy are calculated based on the following formula:

When cooling is required, a “cooling rate” that varies with the outdoor air temperature is calculated using the formula:

The minutes before occupancy are on the following formula:

If the Automatic Update Flag is set to “Yes”, the controller revises the optimal start parameters after each start in which they are used and the temperature change is significant.

External Time SchedulingAn external time clock can be used to schedule unit opera-tion. This is accomplished by a field supplied external time clock signal in the form of a set of dry contacts wired across terminals 101 and 102 on the unit field terminal block TB2 (binary input MCB-BI1). In this case, all internal daily schedules should be set to “00:00-00:00” (default setting). For details on how to connect an external time clock, refer to “Field Wiring” in IM 696, MicroTech II Applied Rooftop Unit Controller.

Network Time SchedulingA network time schedule can be used to operate the unit. In this case, all internal daily schedules should be set to “00:00-00:00” (default setting). Scheduling a unit via a network sig-nal is supported through optional communication modules (BACnet®/IP, BACnet MS/TP and LonMark®).

Alarm MonitoringAbout AlarmsThe MicroTech II Applied Rooftop Unit Controller is pro-grammed to monitor the unit for alarm conditions. Alarm conditions are categorized in three types: “faults”, “prob-lems”, and “warnings.” In general, “faults” are more serious than “problems” and “problems” more serious that “warn-ings.” Therefore, “faults” are assigned a higher priority than “problems” and “problems” a higher priority than “warn-ings.” Within the three types, the alarms are prioritized. Some alarms require manual clearing and some are cleared automatically. Table on page 53 summarizes all alarms, list-ing them by type and priority, and listing the required clear-ing method.If an alarm condition occurs, the controller displays a mes-sage and executes the appropriate action to make the unit fail-safe. The controller displays a local message on the unit keypad/display and a remote indication via a Remote Alarm Output (binary output MCB-BO4) wired to terminals for field connection. For the meaning of each alarm, see “Alarm Control” on page 98.

Table 19: Programmable Parameter


Menu Name Item Name

Zone CoolingEff Clg Spt= 75.0 ºF Effective Cooling Enable Set PointClg Deadband= 1.0 ºF Cooling Enable Deadband

Zone HeatingEff Htg Spt= 75.0 ºF Effective Heating Enable Set PointHtg Deadband= 1.0 ºF Heating Enable Deadband

Optimal Start

Optimal Start= No Optimal Start FlagAuto Update= Yes Automatic Update FlagHtg Rate= 0.4 ºF/min Heating RateHtg OAT= 35.0 ºF Heating Outdoor Air TemperatureHtg Zero OAT= 0 ºF Heating Outdoor Air Temperature ZeroClg Rate= 0.4 ºF/min Cooling RateClg OAT= 85.0 ºF Cooling Outdoor Air TemperatureClg Zero OAT= 100 ºF Cooling Outdoor Air Temperature Zero

Calculated Heating Rate Heating Rate Current OA Temperature Heating Outdoor Air Temperature Zero–Heating Outdoor Air Temperature Heating Outdoor Air Temperature Zero–---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------×=

Minutes Before Occupancy Effective Heating Enable Set Point Current Space Temperature–Calculated Heating Rate

------------------------------------------------------------------------------------------------------------------------------------------------------------=

Calculated Cooling Rate Cooling Rate Cooling Outdoor Air Temperature Zero Current OA Temperature–Cooling Outdoor Air Temperature Zero Cooling Outdoor Air Temperature–---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------×=

Minutes Before Occupancy Current Space Temperature Effective Cooling Enable Set Point–Calculated Cooling Rate

------------------------------------------------------------------------------------------------------------------------------------------------------------=

McQuay OM 138-3 53

Table 20: Unit Alarms

Alarm Type Alarm Message Indication Alarm Reset

Fault

Freeze Freezestat condition while SAF on ManualSmoke Smoke detected by SAF and/or RAF smoke detector Manuala

Space Sensor Space temp sensor failure when CtrlTemp Src= parameter is set to “Space” ManualReturn Sensor RAT sensor failure ManualDisch Sensor DAT sensor failure Manual

Hi Return Tmp RAT exceeded the Hi Return Tmp setting ManualHi Disch Tmp DAT exceeded the Hi Disch Tmp setting ManualLo Disch Tmp DAT fell below the Lo Disch Tmp setting Manual

Fan Fail Airflow not sensed by PC7 after SAF was started ManualOA Dmpr Stuck OA Dampers < 50% open after Startup (100% OA units only) Manual

Problem

Freeze Freezestat tripped while SAF was off AutomaticOAT Sensor OAT sensor failure when CtrlTemp Src= parameter not set to “OAT” Automatic

Space Sensor Space temp sensor failure on unit with RAT sensor AutomaticReturn Sensor RAT sensor failure when CtrlTemp Src= parameter not set to “Return” AutomaticEnt Fan Sensor EFT sensor failure Automatic

Lo Airflow Excessive temperature rise sensed across heat section ManualHeat Fail Gas furnace safety lockout condition occurred Automaticb

Hi Pres-Ckt1 HP1 or HP3 open indicating ckt # 1 high refrigerant pressure ManualHi Pres-Ckt2 HP2 or HP4 open indicating ckt # 2 high refrigerant pressure ManualLo Pres-Ckt1 LP1 remained opened after ckt #1 solenoid valve open Automaticc

Lo Pres-Ckt2 LP2 remained opened after ckt #2 solenoid valve open Automaticc

Frost-Ckt1d Evaporator coil frost condition occurred on ckt #1 Automaticc

Frost-Ckt2d Evaporator coil frost condition occurred on ckt #2 Automaticc

Comp #1 Alm Comp #1 off on low oil pressure (OP1) or motor protector (MP1) Automaticc






Ckt1 Clg Ena Clg enable input to CCB1 off when cooling was on ManualCkt2 Clg Ena Clg enable input to CCB2 off when cooling was on Manual

GenC Clg Ena Clg enable input to GCB1 off when cooling was on ManualHtgB Htg Ena Htg enable input to EHB1 off when heating was on Manual

Ckt1 Comm Fail Comm failure occurred between MCB and CCB1 AutomaticCkt2 Comm Fail Comm failure occurred between MCB and CCB2 Automatic

GenC Comm Fail Comm failure occurred between MCB and GCB1 AutomaticHtgB Comm Fail Comm failure occurred between MCB and EHB1 Automatic

ERecB Comm Fail Comm failure occurred between MCB and ERB1 Automatic

Warning

PumpDown-Ckt1 LP1 still closed 180 seconds into ckt #1 pumpdown operation ManualPumpDown-Ckt2 LP2 still closed 180 seconds into ckt #2 pumpdown operation Manual

Airflow Switch PC7 sensed airflow when unit was off ManualDirty Filter Pressure drop across first filter section exceeded the setting of PC5 Manual

Dirty FnlFltr Pressure drop across final filter section exceeded the setting of PC6 Manual

a. The SAF and RAF smoke detectors must be manually reset after tripping. This can be accomplish be cycling control system power (S1 Switch).b. A manual reset of the flame safeguard control FSG is required before the Heat Fail problem clears.c. Manual clearing is required if this alarm occurs three times within a 24-hour period (2:00 a.m. of one day until 2:00 a.m. of the next). The oil pressure safety devices require a

manual reset on the device.d. Not applicable on units equipped with hot gas bypass.

54 McQuay OM 138-3

Remote Alarm IndicationThe MicroTech II control system includes a Remote Alarm Output (MCB-B04) to provide remote indication of alarm conditions. Under normal (no active alarm) conditions, the Remote Alarm Output (MCB-B04) is closed. The LED asso-ciated with the alarm output indicates the state of the output: On indicates MCB-B04 is closed, and off indicates MCB-B04 is open. The Remote Alarm Output can be connected to some type of field-supplied annunciator. If an alarm occurs, the Remote Alarm Output condition changes to either an “off” or “blinking” state. Each possible alarm condition can be set up to cause the output to either blink rapidly, blink slowly, turn off or remain on (no remote indication of the alarm). Refer to “Configuring Remote Alarm Output” on page 57.

Note: If there are multiple active alarms, only the highest priority alarm affects this output. This is always the alarm indicated by the Active Alarm 1 menu. Refer to “Remote Alarm Output” in the “Field Wiring” section of IM 696, MicroTech II Applied Rooftop Unit Controller.

Figure 6:Active and Previous Alarm Menu Display

Local Alarm Indication (Keypad/Display)Alarm information is provided via the unit keypad/display by four “active” and eight “previous” alarm menus.Up to four active alarms are displayed in the Active Alarm 1, Active Alarm 2, Active Alarm 3, and Active Alarm 4 menus. The highest priority active alarm is displayed in the Active Alarm 1 menu, the second highest priority active alarm in the Active Alarm 2, the third highest priority active alarm in the Active Alarm 3 and the forth highest priority active alarm in the Active Alarm 4 menu. If it happens that there are more than four active alarms, the additional alarms do not appear until one of these four active alarms are cleared.When an active alarm is cleared the remaining active alarms are resorted such that the highest priority active alarm remaining is displayed in Active Alarm 1, the second highest priority active alarm remaining is displayed in Active Alarm 2 and so forth. Figure 6 shows the typical display of an active alarm menu. The first line of the display is the menu line, the second line indicates the alarm name, the third line indicates the alarm “type” (fault, problem, or warning) and the forth line indicates the date and time the alarm occurred. Whenever there is an active alarm, a red alarm LED on the unit keypad turns on. If there are no active alarms, this LED remains off.

When an active alarm is cleared, it is stored in the Previous Alarm 1 menu. Any alarm that might be in the Previous Alarm 1 menu is moved to the Previous Alarm 2 menu, any alarm that might be in the Previous Alarm 2 menu is moved to the Previous Alarm 3 menu and so forth. Any alarm that might be in the Previous Alarm 8 menu is permanently remove from the keypad. Figure 6 shows a typical display of a previous alarm menu. The first line of the display is the menu line, the second line indicates the alarm name, the third line indicates the alarm “type” (fault, problem, or warning) and the forth line indicates the date and time the alarm occurred.Displaying AlarmsActive Alarms. When an active alarm exists the red LED on the keypad is on. The active alarm or alarms can be viewed as follows:

1. Pressing the Alarm key while the red LED on the key-pad is on changes the display to the Active Alarm 1 menu.

2. Pressing the Right Arrow key changes the display to the Active Alarm 2 menu. Pressing the Right Arrow key again changes the display to the Active Alarm 3 menu. Pressing the Right Arrow key again changes the display to the Active Alarm 4 menu.

3. Pressing the Left Arrow key changes the display back to the Active Alarm 3 menu. Repeating this key two more times changes the display back to the Active Alarm 1 menu.

Previous Alarm. When active alarms are cleared, they are stored in the previous alarm menus. The previous alarm menus can be viewed as follows:

1. Pressing the Back/Cancel key changes the display to back to the main menu if not already there.

Active Alarm 1Dirty FilterWarning-Active12-Mar-00 04:50:49

Menu Line

Alarm Name Item Line

Alarm Type Item Line

Alarm Date/Time Item Line

McQuay OM 138-3 55

2. Assuming the blinking cursor is positioned on the Sys-tem Summary menu, pressing the Down Arrow (-) key six times changes the cursor position to the Previous Alarms menu.

3. Pressing the Enter/Save key changes the display to the Previous Alarm 1 menu.

4. Pressing the Right Arrow key changes the display to the Previous Alarm 2 menu. Pressing the Right Arrow key again changes the display to the Previous Alarm 3 menu. Pressing the Right Arrow key five more times changes the display to the Previous Alarm 8 menu.

5. Pressing the Left Arrow key changes the display back to the Active Alarm 7 menu. Repeating this six more times changes the display back to the Previous Alarm 1 menu.

Clearing Alarms. Before any active alarm is cleared, the alarm conditions that caused it must have returned to normal. When the alarm conditions are no longer present, an active alarm may be cleared either automatically or manually.

Note: Some of the safety devices that detect alarm condi-tion require a manual reset at the device before the alarm can be cleared. Refer to Table on page 53 for listing of possible alarms and to determine whether an alarm is manual or automatic reset.

An automatic reset active alarm immediately clears when the alarm conditions that caused it disappear. A manual reset active alarm is cleared using the keypad/display as follows.

1. The active alarm to be cleared is first displayed. Refer to “Displaying Alarms” on page 55.

2. Pressing the Clear Alarm key while the active alarm to be cleared is in the display sends a clear command to the controller. This clears the active alarm and returns the unit to normal operation if no other alarms are active.

Remote Alarm ClearingAlthough it is always recommended that active alarms be cleared at the unit via the keypad/display, there are other methods that effectively clear active alarms. Three such methods are described in the following sections.Unit System Switch (S1)Cycling the main controller system switch (S1) located in the unit main control panel has the effect of clearing the active alarm menus. The disadvantage of clearing alarms in this manor is that the active alarm data is not placed into the pre-vious alarm buffer and alarm information is lost.

Note: Turning off the unit power disconnect switch has the same effect.

Manual Unit Enable/Disable Input Disabling the unit via the manual unit enable/disable input (this occurs when a field supplied and installed switch across terminals 101 and 104 on the unit field terminal block (TB2) is changed from the on (closed) to off (open) position. Refer to the “Manual Unit Enable/Disable” section of IM 696, MicroTech II Applied Rooftop Unit Controller.Network SignalThe active alarms can be cleared via a network signal through optional communication modules (including (BAC-net®/IP, BACnet MS/TP and LonMark®).

56 McQuay OM 138-3

Configuring Remote Alarm Output



Menu Name Item Name

Alarm Out Faults

Freeze= Fast Freeze Fault Remote Output SetupSmoke= Fast Smoke Fault Remote Output Setup

Space Sensor= Fast Space Sensor Fault Remote Output SetupReturn Sensor= Fast Return Sensor Fault Remote Output Setup Disch Sensor= Fast Disch Sensor Fault Remote Output Setup

Hi Return Tmp= Fast Hi Return Tmp Fault Remote Output SetupHi Disch Tmp= Fast Hi Disch Tmp Fault Remote Output SetupLo Disch Tmp= Fast Lo Disch Tmp Fault Remote Output Setup

Fan Fail= Fast Fan Fail Fault Remote Output SetupOA Dmpr Stuck= Fast OA Dmpr Stuck Fault Remote Output Setup

Alarm Out Problems

Freeze= Slow Freeze Problem Remote Output SetupOAT Sensor= Slow OAT Sensor Problem Remote Output Setup

Space Sensor= Slow Space Sensor Problem Remote Output SetupReturn Sensor= Slow Return Sensor Problem Remote Output SetupEnt Fan Sensor= Slow Ent Fan Sensor Problem Remote Output Setup

Lo Airflow= Slow Lo Airflow Problem Remote Output SetupHeat Fail= Slow Heat Fail Problem Remote Output Setup

Hi Pres-Ckt1= Slow Hi Pres-Ckt1 Problem Remote Output SetupHi Pres-Ckt2= Slow Hi Pres-Ckt2 Problem Remote Output SetupLo Pres-Ckt1= Slow Lo Pres-Ckt1 Problem Remote Output SetupLo Pres-Ckt2= Slow Lo Pres-Ckt2 Problem Remote Output Setup

Frost-Ckt1= Slow Frost-Ckt1 Problem Remote Output SetupFrost-Ckt2= Slow Frost-Ckt2 Problem Remote Output Setup

Comp #1 Alm= Slow Comp #1 Alm Problem Remote Output SetupComp #2 Alm= Slow Comp #2 Alm Problem Remote Output SetupComp #3 Alm= Slow Comp #3 Alm Problem Remote Output SetupComp #4 Alm= Slow Comp #4 Alm Problem Remote Output SetupComp #5 Alm= Slow Comp #5 Alm Problem Remote Output SetupComp #6 Alm= Slow Comp #6 Alm Problem Remote Output SetupCkt1 Clg Ena= Slow Ckt1 Clg Ena Problem Remote Output SetupCkt2 Clg Ena= Slow Ckt2 Clg Ena Problem Remote Output Setup

GenC Clg Ena= Slow GenC Clg Ena Problem Remote Output SetupHtgB Htg Ena= Slow HtgB Htg Ena Problem Remote Output Setup

Ckt1 Comm Fail= Slow Ckt1 Comm Fail Problem Remote Output SetupCkt2 Comm Fail= Slow Ckt2 Comm Fail Problem Remote Output Setup

GenC Comm Fail= Slow GenC Comm Fail Problem Remote Output SetupHtgB Comm Fail= Slow HtgB Comm Fail Problem Remote Output Setup

ERecB Comm Fail= Slow ERecB Comm Fail Problem Remote Output Setup

Alarm Out Warnings

PumpDown-Ckt1= Slow PumpDown-Ckt1 Warning Remote Output SetupPumpDown-Ckt2= Slow PumpDown-Ckt2 Warning Remote Output Setup

Airflow Switch= Off Airflow Switch Warning Remote Output SetupDirty Filter= Off Dirty Filter Warning Remote Output Setup

Dirty FnlFltr= Off Dirty FnlFltr Warning Remote Output Setup

McQuay OM 138-3 57

Each possible alarm condition can be configured to cause the Remote Alarm Output (MCB-B04) to blink rapidly, blink slowly, turn off, or remain on (no remote indication of the alarm). This allows the action of the Remote Alarm Output to be “tailored” according to the specific requirements of the application. When there are no active alarms within the con-troller the Remote Alarm Output is “on” continuously. If an alarm output setup parameter is set to “Slow”, the Remote Alarm Output cycles on and off at a slow rate when the alarm occurs. If an alarm output setup parameter is set to “Fast”, the Remote Alarm Output cycles on and off at a rapid rate when the alarm occurs. If an alarm output setup parame-ter is set to “Off”, the Remote Alarm Output turns off when the alarm occurs. If an alarm output setup parameter is set to “On”, the Remote Alarm Output remains on when the alarm occurs.For example, it may be necessary that only alarms that shut a unit off completely (faults) be indicated remotely. In this case all of the “fault” alarms are set to “Slow”, “Fast” or “Off.” All others are set to “On.”Refer to “Remote Alarm Output” in the “Field Wiring” sec-tion of IM 696, MicroTech II Applied Rooftop Unit Controller.

Setting Alarm Limits

Three of the alarm faults have adjustable limits that are used to trigger the alarm. These are the Hi Disch Tmp, Lo Disch Tmp and Hi Return Tmp faults. Although the default settings should be suitable for most applications, the alarm limits can be set as necessary via the unit keypad/display. The default settings are shown in the table above.

Unit Configuration/Service ParametersCalibrate Mode

Calibrate Mode is a special service mode used to calibrate control actuator feedback signals and to zero static pressure sensor inputs. When the Calibrate Mode Flag is set to “Yes”, the position feedback potentiometers on the outdoor air damper, return or exhaust fan inlet vane, modulating cooling valve and modulating heating valve actuators are automati-cally calibrated. Any unit static pressure transducers are also calibrated (or zeroed). The following is a description of the Calibrate Mode procedure.When the Calibrate Mode Flag is set to “Yes”, the Occu-pancy= parameter is overridden and is set to “Unocc” and accordingly the unit shuts off. When the unit is off the out-door air dampers, return or exhaust vanes, modulating cool-ing valve, and modulating heating valve actuators are driven to the 100% open position for three minutes. After three minutes, the controller records the analog input feedback values from the actuators as equivalent to their fully open positions. The controller then drives the actuators to the opposite or fully “closed” position for three minutes. After three minutes, the controller records the analog input feed-back values from the actuators as equivalent to their fully closed positions. The controller also records the analog input voltage signals from all connected pressure transducers as equivalent to 0“ W.C.

Note: It is best to calibrate the unit with all the sensing tubing to the static pressure sensors disconnected. This assures that the sensors are truly seeing 0“ WC when calibrated.

After the Calibrate Mode procedure is complete, the Ctrl Mode= parameter is set to “Off” which means the unit remains off until the Ctrl Mode= parameter is set to some-thing other than “Off” as described in “Auto/Manual Opera-tion” on page 47.

Note: If the Calibrate Mode Flag is set to “Yes” while the Manual Control= parameter in the Manual Control menu is set to “Yes”, the Manual Control= parame-ter reverts to “No.”



Menu Name Item Name

Alarm Limits

Hi Disch Alm= 170 ºF High Discharge Air Tem-perature Alarm Limit

Lo Disch Alm= 40 ºF Lo Discharge Air Temper-ature Alarm Limit

Hi Return Alm= 120 ºF High Return Air Tempera-ture Alarm Limit



Menu Name Item Name

Unit Configuration Calibrate Mode= No Calibrate Mode Flag

58 McQuay OM 138-3

Zone (Space) Temperature Sensor

An optional zone (space) temperature sensor can be installed in the field and wired to the unit. When the optional sensor is installed, the Space Sensor Present Flag should be set to “Yes.” When the optional sensor is not installed, the Space Sensor Present Flag must be set to “No” to deactivate alarm functions associated with an open circuit at the space tem-perature analog input to the controller. The factory setting for the Space Sensor Present Flag is “Yes.” The optional space temperature sensor is required to take advantage of the MicroTech II unoccupied heating (night setback) and cooling (night setup and purge) functions. These functions are disabled when the Space Sensor Present Flag is set to “No.” Also, optimal start and the option of set-ting the CtrlTemp Src= parameter to “Space” are not avail-able when the Space Sensor Present Flag is set to “No.”Refer to “Zone Temperature Sensor Packages” in the “Field Wiring” section of IM 696, MicroTech II Applied Rooftop Unit Controller.

Miscellaneous Service Parameters

The Unit Configuration menu contains several miscella-neous control parameters as listed in the table above. These parameters are generally the type that are set at the factory and might be adjusted when the equipment is started up and

generally do not required further adjustment. The following sections describe these parameters.EFT SensorWhen a unit is equipped with gas or electric heat, it is equipped with an entering fan temperature (EFT) sensor. This sensor senses the temperature of the air entering the dis-charge air fan and is compared to the unit discharge air tem-perature to obtain an indication of the temperature rise across the gas or electric heat section. The controller uses this infor-mation to assure the heat rise across the heater does not exceed the safe limit for the heat exchanger. When the enter-ing fan temperature sensor is installed the Entering Fan Sen-sor Present Flag is set to “Yes.” When the entering fan temperature sensor is not installed the Entering Fan Sensor Present Flag is set to “No.” Setting this parameter to “No” disables the alarm function associated with an open circuit at the EFT temperature sensor input.2nd P SensorThe Second Pressure Sensor Present Flag is used to indicate whether or not an optional building static pressure sensor is installed in the “second sensor” input location.

Note: When the unit is equipped for zone (or space com-fort) control, the “second sensor” input location is design only for a building static pressure input. There is no “first sensor” location.

The Second Pressure Sensor Present Flag should be set to “None” when the Return/Exhaust Fan Capacity Control Flag is set to “None” or “Position”. When the Return/Exhaust Fan Capacity Control Flag is set to “Bldg”, the Second Pressure Sensor Present Flag automatically reverts to “Bldg”. For detailed information regarding return fan capacity control, refer to “Return Fan Capacity Control” on page 94.RF/EF CtrlThe Return/Exhaust Fan Capacity Control Flag is used to select the type of return or exhaust fan capacity control. When the unit is not equipped with return fan vanes or a VFD, the Return/Exhaust Fan Capacity Control Flag should be set to “None”. When the unit is equipped with return fan vanes or a VFD, the Return/Exhaust Fan Capacity Control Flag can either be set to “Bldg” or “Position”.When the Return/Exhaust Fan Capacity Control Flag is set to “Bldg”, the return or exhaust fan capacity is controlled to maintain the building static pressure at a building static pressure set point. When the Return/Exhaust Fan Capacity Control Flag is set to “Position”, then the return or exhaust fan capacity is controlled to the Remote Return/Exhaust Fan Capacity Set Point. For detailed information regarding return or exhaust fan capacity control, refer to“Return Fan Capacity Control” on page 94 or “Energy Recovery” on page 91.



Menu Name Item Name

Unit Configuration Space Sensor= Yes Space Sensor Present Flag



Menu Name Item Name

Unit Configuration

EFT Sensor= No Entering Fan Sensor Present Flag

2nd P Sensor= None Second Pressure Sensor Present Flag

RF/EF Ctrl= TrackingReturn/Exhaust Fan

Capacity Control Flag

Rem RF/EF Cap= 25%

Remote Return/Exhaust Fan Capacity Set Point

Eng Units= English Engineering Units Control Flag

McQuay OM 138-3 59

Rem RF/EF CapThe the return or exhaust fan capacity is controlled to main-tain the Remote Return/Exhaust Fan Capacity Set Point when the Return/Exhaust Fan Capacity Control Flag is set to “Position”. The Remote Return/Exhaust Fan Capacity Set Point is normally adjusted via a network signal but can also be adjusted via the keypad/display in the absence of a net-work connection to the parameter. For detailed information regarding return or exhaust fan capacity control, refer to“Return Fan Capacity Control” on page 94 or “Energy Recovery” on page 91.Eng UnitsThe Engineering Units Control Flag is used to select the sys-tem of engineering units used for displaying data on the key-pad. If this parameter is set to “English”, the keypad data is displayed in inch-pound (I-P) units. If this parameter is set to “SI Canada”, the keypad data is displayed in the Interna-tional System of Units (SI) used in Canada. If this parameter is set to “SI Europe”, the keypad data is displayed in the International System of Units (SI) used in Europe.

Control Timer Settings

Several MicroTech II internal control timers can be adjusted via the keypad/display Timer Settings menu. The following sections describe these timers.ServiceMany of the internal control timers can be temporarily sped up by using the Fast Service Timer. When set to a time value, the Fast Service Timer begins counting down. While this parameter is counting down the following normal unit timers are set to the values indicated below:

• Startup Initialization Timer - 20 seconds• Cooling Interstage Timer - 2 minutes• Heating Interstage Timer - 20 seconds

These timers return to their normal settings if the Fast Ser-vice Timer is manually set to 0 or when it counts down to 0.

Note: This fast timers feature is meant to be used only by a knowledgeable service technician to facilitate testing the unit.

RecirculateThe Recirculate State Timer defines the duration of the Recirc operating state applicable on units with return air (100% OA units have no Recirc operating state). Whenever a unit with return air is started or restarted, it always transi-tions through a “start sequence” which includes the Startup, followed by the Recirc operating state. During the Recirc operating state, the unit fans run while the outdoor air damp-ers remain closed. Heating and cooling operation are dis-abled during the Recirc operating state to allow the “system” air temperature conditions to equalize before temperature control begins. Once in the Recirc operating state, the unit remains there until the Recirculate State Timer expires. Low DATThe Low Discharge Temperature Ignore Timer sets the dura-tion of a time period upon unit start up during which the Lo Disch Tmp fault is ignored. This may be particularly impor-tant in colder climates when a unit has been off for a signifi-cant time period during which the unit, including the discharge air temperature sensor, has become very cold. This time period allows the unit to run long enough to warm the discharge sensor above the alarm limit, preventing nuisance unit alarm shutdown. For detailed information regarding the Lo Disch Tmp fault refer to “Alarm Control” on page 98.Max MWUThe Maximum Morning Warm-up Timer sets a maximum duration for the MWU operating state applicable on units with return air (100% OA units have no MWU operating state). Whenever a unit with return air leaves the Recirc operating state, it enters the MWU operating state if the Ctrl Temp= parameter value is cold. The unit remains in the MWU operating state until either the Ctrl Temp= parameter value warms up or until the Maximum Morning Warm-up Timer expires. For detailed information regarding MWU operation, refer to “Heating: Multistage” on page 83, or “Heating: Modulating” on page 85, as applicable.Tnt OvrdThe Tenant Override Time Increment sets the time period for which the unit operates each time the tenant override button on the optional space temperature sensor is pressed or the Occ Mode= parameter is set to “Tnt Ovrd.” The Tnt Ovrd= parameter in the Occupancy menu is set or reset to this value when the tenant override button is pressed or the Occ Mode= parameter is set to “Tnt Ovrd.” The unit then operates until the Tnt Ovrd= parameter counts down to 0. For detailed information regarding tenant override operation, refer to “Tenant Override” on page 50.



Menu Name Item Name

Timer Settings

Service= 0 min Fast Service Timer

Recirculate= 3 min Recirculate State Timer

Low DAT= 3 min Low Discharge Tem-perature Ignore Timer

Max MWU= 90 min Maximum Morning Warm-up Timer

Tnt Ovrd= 120 min Tenant Override Time Increment

Start Init= 120 min Startup Initialization Timer

60 McQuay OM 138-3

Start InitThe Startup Initialization Timer defines the duration of the Startup operating state. When a unit is started or restarted, it always transitions through a “start sequence” that begins with the Startup operating state. During the Startup operating state, the unit fans remain off and heating and cooling are disabled. On units equipped with return air, the outdoor air damper actuator is driven closed. On units equipped with 100% outdoor air hoods, the outdoor air dampers are driven fully open. Return fan inlet vane actuators (if present) are driven to a 17% minimum startup position. Refer to “Operat-ing States and Sequences” on page 63.

Manual Output Control

The Manual Control menu is a special service menu that can be used to control many of the outputs on the main control board (MCB) in a manual mode. This can be used to test the operation of the various devices controlled by the outputs. This is very useful in determining whether a problem is the result of a wiring problem or defective device rather than a problem within the main controller.Manual ControlThe Manual Control Mode Flag is used to turn the manual control mode of operation on and off. When this parameter is

set to “No” the unit operates normally. When this parameter is set to “Yes” normal operation of the control outputs is overridden and the condition of each output is defined by setting the remaining items within the Manual Control menu. All alarms are inactive when the Manual Control Mode Flag is set to “Yes”.

Note: If the Calibrate Mode= parameter in the Unit Con-figuration menu is set to “Yes” while the Manual Control Mode Flag is set to “Yes”, the Manual Con-trol Mode Flag reverts to “No.”

Discharge FanThe Manual Discharge Fan Control Flag is used to manually turn the discharge air fan on and off. When the Manual Con-trol Mode Flag is set to “Yes” and this parameter is set to “On” the discharge air fan is turned on. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Off” the discharge air fan is turned off.RF/EF FanThe Manual Return/Exhaust Fan Control Flag is used to manually turn the return or exhaust fan on and off. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “On” the return or exhaust fan is turned on. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Off” the return or exhaust fan is turned off.Fan OperationThe Manual Fan Operation Output Control Flag is used to manually turn the Fan Operation Output (MCB-BO3) on and off. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “On” the Fan Operation Output is turned on. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Off” the Fan Operation Output is turned off. For detailed information regarding the Fan Operation Output, refer to “Fan Operation Output” in the “Field Wiring” section of IM 696, MicroTech II Applied Rooftop Unit Controller.AlarmThe Manual Remote Alarm Output Control Flag is used to manually turn the Remote Alarm Output (MCB-BO4) on and off. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Normal” the Remote Alarm Output is turned on. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Alarm” the Remote Alarm Output is turned off. For detailed information regard-ing the Remote Alarm Output, refer to “Remote Alarm Out-put” in the “Field Wiring” section of IM 696, MicroTech II Applied Rooftop Unit Controller.



Menu Name Item Name

Manual Control

Manual Control = No Manual Control Mode Flag

Discharge Fan = Off Manual Discharge Fan Control Flag

RF/EF Fan = OffManual

Return/Exhaust Fan Control Flag

Fan Operation = Off Manual Fan Operation Output Control Flag

Alarm = Normal Manual Remote Alarm Output Control Flag

OA Damper = Auto Manual OA Damper Control Flag

Mod Cooling = AutoManual Modulating

Cooling Valve Control Flag

Mod Heating = AutoManual Modulating

Heating Valve Control Flag

RF/EF Vanes = AutoManual

Return/Exhaust Vane Actuator Control Flag

RF/EF VFD = AutoManual

Return/Exhaust VFD Control Flag

McQuay OM 138-3 61

OA DamperThe Manual OA Damper Control Flag is used to manually drive the outdoor air dampers open and closed. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Open” the open outdoor damper output (MCB-BO6) is turned on and the outdoor air dampers stroke open continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Close” the close outdoor damper output (MCB-BO5) is turned on and the outdoor air dampers stroke closed continuously. When the Manual Con-trol Mode Flag is set to “Yes” and this parameter is set to “Auto” the open and close outdoor damper outputs remain off and the outdoor air dampers remain at their current posi-tion.Mod CoolingThe Manual Modulating Cooling Valve Control Flag is used to manually drive the modulating cooling valve open and closed. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Open” the open cooling valve output (MCB-BO8) is turned on and the cooling valve strokes open continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Close” the close cooling valve output (MCB-BO7) is turned on and the cooling valve strokes closed continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Auto” the open and close cooling valve outputs remain off and the cooling valve remains at its current position.Mod HeatingThe Manual Modulating Heating Valve Control Flag is used to manually drive the modulating heating valve open and closed. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Open” the open heating valve output (MCB-BO10) is turned on and the heating valve strokes open continuously. When the Manual Control Mode

Flag is set to “Yes” and this parameter is set to “Close” the close heating valve output (MCB-BO9) is turned on and the heating valve strokes closed continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Auto” the open and close heating valve outputs remain off and the heating valve remains at its current position.RF/EF VanesThe Manual Return/Exhaust Vane Actuator Control Flag is used to manually drive the return air or exhaust fan inlet vanes open and closed. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Open” the open return or exhaust inlet vanes output (MCB-BO16) is turned on and the vanes stroke open continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Close” the close return or exhaust inlet vanes out-put (MCB-BO15) is turned on and the vanes are stroked closed continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Auto” the open and close return or exhaust inlet vanes outputs remain off and the vanes remain at their current position.RF/EF VFDThe Manual Return/Exhaust VFD Control Flag is used to manually increase and decrease the return air or exhaust fan VFD speed. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Faster” the increase return or exhaust fan VFD speed output (MCB-BO-16) is turned on and the VFD speed increases continuously. When the Man-ual Control Mode Flag is set to “Yes” and this parameter is set to “Slower” the decrease return or exhaust fan VFD speed output (MCB-BO15) is turned on and the VFD speed decreases continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Auto” the increase and decrease return or exhaust fan VFD speed out-puts remain off and the VFD remains at its current position.

62 McQuay OM 138-3

Description of OperationThe following sections describe how the various zone (or space comfort) control unit processes function to maintain temperature, ventilation and pressure control. The “Operat-ing States and Sequences” section provides an overall description of unit operation. The subsequent sections pro-vide detailed descriptions of the various control processes and how the related set points and parameters affect them. The related set points and parameters are listed at the begin-ning of each applicable sub-section. The default keypad pro-grammable values are shown in italic letters.

Note: Not all the features covered in this section apply to all units depending on the specific unit options. The applicable items should be read and understood before making set point or control parameter changes.

Operating States and SequencesAbout Operating StatesOperating states define the current overall status of the roof-top unit. The operating state can be displayed and the unit operating condition can be quickly determined by viewing the UnitStatus= parameter in the System menu. Each operat-ing state summarizes the following information:

• Discharge and return/exhaust fan status• Outdoor air damper status• Return/exhaust airflow capacity• Heating system status• Cooling system status• Fan Operation Output status (MCB-BO3)

Table 28 shows the all the normal operating states and the status information they summarize.

Operating State DescriptionsThe following sections describe each of the unit operating states.OffThere are five different Off operating states. In any of the Off operating states the unit is shut down. The fans are off and the outdoor air dampers are closed, any fan inlet vanes or VFD is driven to 0%. Cooling and heating are disabled. The Fan Operation Output (MCB-BO3) is open.The five different Off operating states are described in the following sections:

Off Unoc. Generally, the unit operating state is Off Unoc when it is being scheduled on and off by a time clock func-tion and the time schedule indicates an unoccupied period. Specifically, the operating state is Off Unoc when the Occu-pancy= parameter indicates “Unocc” and none of the unoc-cupied unit operation functions are active. For details regarding the Occupancy= parameter refer to “Occupancy” on page 48. For details regarding unoccupied unit operation functions refer to “Propeller Exhaust Fan Control” on page 95.

Off Net. The unit operating state is Off Net when the Appl Mode= parameter is set to “Off” via a network signal and the Ctrl Mode= parameter is set to “Auto.” For detailed infor-mation regarding the Appl Mode= and Ctrl Mode= parame-ter, refer to “Auto/Manual Operation” on page 47.The unit operating state is also Off Net when the Emerg Override= parameter in the Occupancy menu is set to “Off.” Refer to “Emergency Override” on page 50.

Table 28: Operating States

Operating State Discharge/ Return Fans

Exhaust Fan(s) OA Dampers Return Airflow

CapacityExhaust Airflow

CapacityHeat

EnabledMechanical

Cooling Enabled

Fan Output (MCB-BO3)

Off Off Off Closed 0% 0% No No Open

Startup Off Off Closedc 0% 0% No No Closed

Recirc On Off Closed Modulating 0% No No ClosedFan Only Off Off Minimum Modulating 0% No No Closed

Econo On Cycling Modulating Modulating Modulating No No Closed

Cooling On Cycling Minimum or Opena Modulating Modulating No Yes Closed

MWU On Off Closed Modulating 0% Yes No ClosedHeating Off Off Minimum Modulating 0% Yes No ClosedMin DAT Off Off Minimum Modulating 0% Yes No Closed

UnocEcon On Cycling Modulating Modulating Modulating No No Closed

UnocClg On Cycling Closed or Openb Modulating Modulating No Yes Closed

UnocHtg On Off Closed Modulating 0% Yes No Closed

a. When the OA Ambient= parameter indicates “Low”, the economizer outdoor air dampers is fully open; when the OA Ambient= parameter indicates “High”, the economizer outdoor air dampers are at Eff Min OA Pos= value.

b. When the OA Ambient= parameter indicates “Low”, the outdoor air dampers are fully open; when the OA Ambient= parameter indicates “High”, the outdoor air dampers are fully closed.

c. Except on 100% OA units. Dampers are driven fully open during the startup operating state in this case.

McQuay OM 138-3 63

Off Sw. The unit operating state is Off Sw when a field sup-plied and installed switch across terminals 101 and 104 on the unit field terminal block (TB2) is in the on or closed position (binary input MCB-BI2 on). Refer to “Manual Unit Enable/Disable” in IM 696, MicroTech II Applied Rooftop Unit Controller.

Off Alm. The unit operating state is Off Alm when an active alarm of the “fault” type has a unit shut down. Refer to “Alarm Monitoring” on page 53 for a description of “fault” alarms.

Off Man. The unit operating state is Off Man when the Ctrl Mode= parameter is set to “Off.” For detailed information regarding the Ctrl Mode= parameter, refer to “Ctrl Mode” on page 47.Startup When a unit is commanded to start, it always enters the Star-tup operating state from the Off operating state. The unit remains in the Startup operating state for an adjustable time period defined by the Start Init= parameter in the Timer Set-tings menu (default value is 180 seconds) before entering the Recirc operating state. During the Startup operating state the unit is prepared for startup. The fans remain off, the outdoor air dampers are driven closed, any fan inlet vanes are driven to a fixed 17% minimum position (VFD remains at 0% speed). Cooling and heating remain disabled. The Fan Oper-ation Output (MCB-BO3) is closed.For more information regarding the Startup operating state, refer to “Startup Control” on page 66.RecircUnits with return air always enter the Recirc operating state after the completion of the Startup operating state. In the Recirc operating state fans are started and operate while the outdoor air dampers remain closed. This allows temperature conditions throughout the unit and space to equalize before temperature control begins. Cooling and heating remain dis-abled. The Fan Operation Output (MCB-BO3) is closed and in building pressure control applications, normal return fan capacity control is maintained. The unit remains in the Recirc operating state until the Recirculate State Timer expires. This timer is adjustable from 2 to 60 minutes with the Recirculate= parameter in the Timer Settings menu.

Note: 100% outdoor air units do not transition through the Recirc operating state.

For more information regarding the Recirc operating state, refer to “Startup Control” on page 66.Fan OnlyThe unit enters the Fan Only operating state during occupied operation when cooling and heating are either not required based on the unit heat/cool changeover function or are dis-abled. During the Fan Only operating state, the outdoor air dampers are either 100% open on a 100% outdoor air unit or are controlled to the Eff Min OA Pos= parameter in the OA

Damper menu. Cooling and heating operation is disabled. The Fan Operation Output (MCB-BO3) is closed and in building pressure control applications, normal return fan capacity control is maintained.EconoThe unit enters the Econo operating state when cooling is required during occupied operation when economizer opera-tion is enabled. During the Econo operating state, mechani-cal cooling and heating are disabled. The outdoor and return air dampers are modulated to maintain the discharge air tem-perature at the Eff Clg Spt= parameter in the Discharge Cooling menu. The Fan Operation Output (MCB-BO3) is closed and in building pressure control applications, normal return fan capacity control is maintained.

Note: 100% outdoor air units do not transition through the Econo operating state.

For detailed information regarding economizer operation, refer to “Economizer” on page 70.CoolingThe unit enters the Cooling operating state during occupied operation when cooling is required and the economizer is either disabled, not present, or already fully opened. During the Cooling operating state, the outdoor air dampers are fully open if the unit is a 100% outdoor air unit or if economizer operation is enabled. The outdoor air dampers are controlled to the Eff Min OA Pos= parameter if economizer operation is disabled or not present. Mechanical cooling is supplied as required to maintain the Ctrl Temp= parameter at the Eff Clg Spt= in the Zone Cooling menu. The Fan Operation Output (MCB-BO3) is closed and in building pressure control appli-cations, normal return fan capacity control is maintained. Heating is disabled.For detailed information regarding the cooling operation, refer to “Cooling: Multistage” on page 75 or “Cooling: Mod-ulating” on page 81 as applicable.MWUWhen the unit transitions from unoccupied to occupied oper-ation and heating is required to warm the Ctrl Temp= param-eter up to the Eff Htg Spt= setting in the Zone Heating menu, the unit enters the MWU (Morning Warm-up) operating state after the Startup and Recirc operating states are complete. The MWU operating state is similar to the Heating operating state except that the outdoor air dampers are held closed rather than controlled to the Eff Min OA Pos= parameter. Once entering the MWU operating state, the unit remains there until either the Ctrl Temp= parameter warms up to the Eff Htg Spt= setting in the Zone Heating menu or until a maximum morning warm-up time period expires. This time period is defined by the Max MWU= parameter in the Timer Settings menu. The Fan Operation Output (MCB-BO3) is closed and in building pressure control applications, normal return fan capacity control is maintained. Cooling is dis-abled.

64 McQuay OM 138-3

Note: 100% outdoor air units do not transition through the MWU operating state.

For detailed information regarding morning warm-up heat-ing operation, refer to “Heating: Multistage” on page 83, or “Heating: Modulating” on page 85 as applicable.HeatingThe unit enters the Heating operating state when heating is required during occupied operation. During the Heating operating state, the outdoor air dampers are either 100% open if the unit is a 100% outdoor air unit or controlled to the Eff Min OA Pos= parameter. Cooling is disabled. The Fan Operation Output (MCB-BO3) is closed and in building pressure control applications, normal return fan capacity control is maintained.For detailed information regarding heating operation, refer to “Heating: Multistage” on page 83, or “Heating: Modulat-ing” on page 85 as applicable.Min DATThe unit enters the Min DAT operating state during occupied operation when neither cooling nor heating is required based on the Eff Clg Spt= and Eff Htg Spt= parameters in the Zone Cooling and Zone Heating menus, but the discharge air tem-perature falls below the MinDAT Limit= parameter in the Discharge Heating menu. The Min DAT operating state pre-vents cold discharge air temperatures during what would normally be the Fan Only operating state. During the Min DAT operating state, the outdoor air dampers are either 100% open if the unit is a 100% outdoor air unit or are con-trolled to the Eff Min OA Pos= parameter. Cooling is dis-abled. The Fan Operation Output (MCB-BO3) is closed and in building pressure control applications, normal return fan capacity control is maintained.For detailed information regarding the Min DAT operating state, refer to “Discharge Air Low Limit Control” on page 84 (multistage heat) or “Discharge Air Low Limit Control” on page 89 (modulating heat) as applicable.UnocEconThe unit enters the UnocEcon operating state if the outdoor air is suitable for free cooling when “purge” or unoccupied cooling (night setup) operation is required. During the Uno-cEcon operating state, the outdoor air dampers are modu-lated to maintain the discharge air temperature at the Eff Clg Spt= parameter in the Discharge Cooling menu. Mechanical cooling is disabled. The Fan Operation Output (MCB-BO3) is closed and in building pressure control applications, nor-mal return fan capacity control is maintained. Heating is dis-abled.

Note: 100% outdoor air units do not transition through the UnocEcon operating state.

For detailed information regarding unoccupied economizer operation, refer to “Unoccupied Control” on page 96 and “Purge” on page 97.

UnocClgThe unit enters the UnocClg operating state when unoccu-pied cooling (night setup) operation is required and the econ-omizer is either disabled, not present, or already fully opened. During the UnocClg operating state, the outdoor air dampers are fully open if the unit is a 100% outdoor air unit or if economizer operation is enabled. The outdoor air damp-ers are at 0% if economizer operation is disabled or not present. The Fan Operation Output (MCB-BO3) is closed and in building pressure control applications, normal return fan capacity control is maintained. Heating is disabled.For detailed information regarding the unoccupied cooling operation, refer to “Unoccupied Control” on page 96.UnocHtgThe unit enters the UnocHtg operating state when unoccu-pied heating (night setback) operation is required. During the UnocHtg operating state, the outdoor air dampers are closed. The Fan Operation Output (MCB-BO3) is closed and in building pressure control applications, normal return fan capacity control is maintained. Cooling is disabled.For detailed information regarding the unoccupied heating operation, refer to “Unoccupied Heating (Night Setback)” on page 96.UnocFanOThe UnocFanO operating state is not a “typical” operating state. If night set back operation is activated while the unit heating is disabled or if the unit is not equipped with heating equipment, the unit with enter the UnocFanO operating state in lieu of the UnocHtg operating state. Unit operation is the same as describe for the Fan Only operating state except that the outdoor air dampers are controlled as in the UnocHtg operating state.The unit will also enter the UnocFanO operating state if cooling or heating are disable while in the UnocEcon, Unoc-Clg or UnocHtg operating states. If entering the UnocFanO operating state from the UnocEcon or UnocClg operating state, the outdoor dampers are control as describe for the UnocClg operating state.For detailed information regarding the unoccupied heating or cooling operation, refer to “Propeller Exhaust Fan Control” on page 95.Man CtrlThe unit enters the Man Ctrl operating state when the Man-ual Control= parameter in the Manual Control menu is set to “Yes”. During manual operation, all the unit control func-tions are disabled and the main control board (MCB) outputs can be turned on and off manually by setting the parameters contained in the Manual Control menu.For detailed information regarding manual unit control, refer to “Manual Output Control” on page 61.

McQuay OM 138-3 65

Figure 7:Operating State Sequence Chart

Operating State Sequence ChartOperating states and the transitions between them help to describe the unit sequences of operation. Figure 7 shows all of the operating state transitions that can occur as a result of normal control. Depending on the unit options, some operat-ing states may not apply.

Startup ControlA rooftop unit can startup and run for a variety of reasons. Examples are the internal time schedule function, an external time clock signal, a tenant override signal or the unoccupied heating (night setback) and cooling (night setup and purge) functions. Regardless of the reason it is started, the unit always transitions through a “controlled” startup sequence before allowing temperature control to begin.

Before Startup

When the controller receives a startup command, its operat-ing state changes from the Off to Startup operating state.

During the Startup operating state, the Fan Operation Output (MCB-BO3) is closed to indicate that the fans are about to start. On units with return fan inlet vanes, the vanes are driven open to the non-adjustable Minimum Inlet Vane Posi-tion Limit. This limit is 17% and is not adjustable. The Min-imum Inlet Vane Position Limit assures that the return fan does not start with a completely blocked airflow path. On units with a return fan VFD, the VFD remains at 0% speed. The unit remains in the Startup operating state until the Star-tup Initialization Timer expires.

Note: On 100% OA units equipped with gas heat, the Startup period may last longer than the period defined by the Startup Initialization Timer if heat is required at unit startup. For a description of this special 100% OA gas heat startup sequence, refer to “Gas Heat” on page 86.

Any State OFF

Startup

Recirc

UnocClg

UnocEcon

Cooling

Economizer

Fan Only

Min DAT

Heating

MWU

UnocHtg



Menu Name Item Name

- - Minimum Inlet Vane Position Limit

Timer Settings Start Init = 3 min Startup Initialization Timer

CAUTIONThe Startup Initialization Timer should be set so that the Startup operating state lasts long enough to allow any field-supplied equipment (such as isolation damper sets) controlled by the Fan Operation Output (MCB-BO3) to prepare for fan operation.

66 McQuay OM 138-3

Fan Startup

Return Air Units The unit enters the Recirc operating state after leaving the Startup operating state. During the Recirc operating state, the fans are stated and operated with the outdoor air dampers closed to allow temperature conditions throughout the unit and space to equalize before temperature control begins. Cooling and heating remain disabled. As soon as the unit leaves the Startup operating state, the dis-charge fan starts and the following three timers are reset and start timing down: (1) the Fan Delay Timer, (2) the Airflow Check Timer, and (3) the Recirculate State Timer.When the Fan Delay Timer expires, the return fan is started (if present). The Fan Delay Timer value is a fixed four sec-onds. Once both fans start, the return fan capacity (if vari-able) is modulated to maintain the building static pressure or position set point as applicable. For detailed information regarding return fan capacity control, refer to “Return Fan Capacity Control” on page 94.The Fan Fail fault which indicates loss of airflow is pre-vented from occurring after leaving the Startup operating state until the Airflow Check Timer expires. The Airflow Check Timer value is a fixed two minutes.Once in the Recirc operating state, the unit remains there until the Recirculate State Timer and Airflow Check Timer expire. After the unit leaves the Recirc operating state, the operating state entered is a function of the current occu-pied/unoccupied as well as the current temperature condi-tions. The Heat/Cool Changeover section describes the heating/cooling changeover function, which dictates whether the unit enters a heating, cooling or the Fan Only operating state. 100% Outdoor Air UnitsIf the unit is equipped with a 100% outdoor air hood, the Recirc operating state is bypassed and the fans are started as the unit directly enters either a heating or the Fan Only oper-ating state after leaving the Startup operating state.

As soon as the unit leaves the Startup operating state, the dis-charge fan starts and the Airflow Check Timer is reset and starts timing down. This timer value is a fixed two minutes.The Fan Fail fault which indicates loss of airflow is pre-vented from occurring after leaving the Startup operating state until the Airflow Check Timer expires. After the unit leaves the Startup operating state, the operat-ing state entered is a function of the current occupied/unoc-cupied as well as the current temperature conditions. The following section describes the heating/cooling changeover function, which dictates whether the unit enters a heating, cooling or Fan Only operating state.

Note: While the Airflow Check Timer is timing down and, therefore, while the Fan Fail fault alarm is being ignored, the unit will not be allowed to enter a cooling operating state.

Heat/Cool ChangeoverIn general, a unit configured for zone (or space comfort) control either operates to maintain the Effective Cooling Enable Set Point using economizer and/or mechanical cool-ing or the Effective Heating Enable Set Point using the heat-ing equipment. The Effective Cooling Enable Set Point and Effective Heat-ing Enable Set Point are not adjustable from the keypad. They are set equal to the Cooling Enable Set Point and Heat-ing Enable Set Point respectively or based on a signal from an optional space temperature sensor with set point adjust-ment capability. For details regarding the use of thermostat supplied set points, refer to “Tstat Source Set Points” on page 68.

Note: Except when the dehumidification function is active, cooling and heating do not operate simulta-neously. The controller prevents the set points and dead bands from being set so that the Cooling Enable Dead Band and Heating Enable Dead Band overlap. In doing this, the controller always gives the Effective Cooling Enable Set Point the highest priority. Regardless of whether the cooling set point is lowered, the heating set point is raised or either of the dead bands are raised, the controller automat-ically lowers the Effective Heating Set Point enough to prevent the dead bands from overlapping.

The following sections describe the unit heat/cool changeover function.



Menu Name Item Name

- - Fan Delay Timer

- - Airflow Check Timer

Timer Settings Recirculate= 3 min Recirculate State Timer

McQuay OM 138-3 67

Temperature Control

Control TemperatureThe “Control Temperature” is defined as the temperature sensor input used to make the heat/cool changeover decision which determines whether the unit is controlling to the Effective Cooling Enable Set Point or the Effective Heating Enable Set Point. Also, when cooling is active, the “Control Temperature” is maintained at the Effective Cooling Enable Set Point and when heating is active the “Control Tempera-ture” is maintained at the Effective Heating Enable Set Point. Either the return air or space temperature sensor can be selected as the “Control Temperature.” When the Control Temperature Source is set to “Return”, the unit return air temperature sensor acts as the “Control Tem-perature.” When the Control Temperature Source is set to “Space”, the unit space air temperature sensor acts as the “Control Tem-perature.”

Note: The Control Temperature Source can not be set to “Return” on a 100% OA unit and it can only be set to “Space” when the unit is equipped with an optional space sensor. This means that an optional space sensor is required on a 100% OA unit.

The current value of the “Control Temperature” can be dis-played be viewing the Ctrl Temp= parameter in the Temper-atures menu.

Once enabled by the “Control Temperature” cooling or heat-ing capacity control operates as described in “Economizer” on page 70, “Cooling: Multistage” on page 75, “Cooling: Modulating” on page 81, “Heating: Multistage” on page 83, or “Heating: Modulating” on page 85 as applicable. The fol-lowing sections describe in detail how the “Control Temper-ature” enables cooling and heating operation.

Note: Although enabled based on the “Control Tempera-ture”, cooling or heating operation can be disabled for other reasons. Refer to “Clg Status” on page 45 and “Htg Status” on page 46.

Set Points and Dead BandsIn determining whether heating or cooling operation is enabled, the controller compares the “Control Temperature” input with the Effective Cooling Enable Set Point and the Effective Heating Enable Set Point.

Keypad/Network Source Set Points. When the Zone Set Point Source Flag is set to “Keypad”, the Effective Cool-ing Enable Set Point and the Effective Heating Enable Set Point are set to the Cooling Enable Set Point and the Heating Enable Set Point respectively. The Cooling Enable Set Point and the Heating Enable Set Point can then be set as required via the keypad or a network signal.

Tstat Source Set Points. When the Zone Set Point Source Flag is set to “Tstat”, the Effective Cooling Enable Set Point and the Effective Heating Enable Set Point are set based on an analog signal from an optional space tempera-ture sensor with set point adjustment capability. To set the Effective Cooling Enable Set Point and the Effec-tive Heating Enable Set Points based on the remote set point input, the controller first determines the difference between the Cooling Enable Set Point to the Heating Enable Set Point. The controller then sets the Effective Cooling Enable Set Point to the current setting on the space sensor plus half this difference. The controller then sets the Effective Heating Enable Set Point to the current setting on the space sensor minus half this difference. For example, if the Cooling Enable Set Point is set to 75°F, the Heating Enable Set Point is set to 70°F and the set point adjustment on the space temperature sensor is set to 70°F, the Effective Cooling Set Point would be set to 72.5°F and the Effective Heating Enable Set Point would be set to 67.5°F.

Cooling. When the “Control Temperature” rises above the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band, cooling operation is enabled and the controller starts to increase the cooling capacity. This is shown as Point A in Figure 8.



Menu Name Item Name

Zone Cooling

CntlTemp Src= Return Control Temperature Source

Eff Clg Spt= ____°F Effective Cooling Enable Set Point

Occ Clg Spt= 75.0 ºF Cooling Enable Set Point

Clg Deadband= 1.0 ºF Cooling Enable Dead Band

Zone Heating

CntlTemp Src= Return Control Temperature Source

Eff Htg Spt= ____°F Effective Heating Enable Set Point

Occ Htg Spt= 70.0 ºF Heating Enable Set Point

Htg Deadband= 1.0 ºF Heating Enable Dead Band

Zone Temp Setup Spt Source= Keypad Zone Set Point Source

Flag

68 McQuay OM 138-3

Figure 8:Illustrative Heat/Cool Changeover Operating Sequence

Cooling to Fan Only. When cooling is active and the “Control Temperature” then drops below the Effective Cool-ing Enable Set Point by more than half the Cooling Enable Dead Band, the controller starts to decrease the cooling capacity. As soon as the cooling is staged or modulate off completely the unit enters and runs in the Fan Only operating state. This shown as Point B in Figure 8.While in the Fan Only operating state and if the unit is equipped with modulating or multistage heat, the unit can operate the heat in this case based on a discharge tempera-ture low limit function if the discharge air temperature gets too cold. Refer to “Discharge Air Low Limit Control” on page 84 (multistage heat) or “Discharge Air Low Limit Con-trol” on page 89 (modulating heat) as applicable.

Heating. When the “Control Temperature” drops below the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band, heating operation is enabled and the controller starts to increase the heating capacity. This is shown as Point C in Figure 8.

Heating to Fan Only. When heating is active and the “Control Temperature” then rises above the Effective Heat-ing Enable Set Point by more than half the Heating Enable Dead Band, the controller starts to decrease the heating capacity. As soon as the heating is staged or modulate off completely the unit enters and runs in the Fan Only operating state. This shown as Point D in Figure 8.While in the Fan Only operating state and if the unit is equipped with modulating or multistage heat, the unit can operate the heat in this case based on a discharge tempera-ture low limit function if the discharge air temperature gets

too cold. Refer to “Discharge Air Low Limit Control” on page 84 (multistage heat) or “Discharge Air Low Limit Con-trol” on page 89 (modulating heat) as applicable.

0-30% Outdoor Air Damper ControlMinimum Ventilation Control

Whenever the unit is in the Fan Only, Cooling, Heating or Min DAT operating state, the outdoor air dampers are pre-vented from closing below the Minimum Outdoor Damper Position Set Point. During the Off, Startup, Recirc, and MWU operating states, the outdoor air dampers are driven continuously to 0%.Unoccupied OperationWhenever the unit is operating in the unoccupied operating states, UnocClg or UnocHtg, the outdoor air dampers are driven continuously to 0%.

A

B

C

D

}

}}

Cooling Enable Dead Band

Fan Only (or MinDAT)

Heating Enable Dead Band

Cooling Enabled

Heating Enabled

Time

Con

trol T

empe

ratu

reEffective CoolingEnable Set Point

Effective HeatingEnable Set Point



Menu Name Item Name

OA Damper

MinOA Type= NoneMinimum Outdoor Damper Position

Reset Flag

MinOA Pos= 10%Minimum Outdoor

Damper Position Set Point

McQuay OM 138-3 69

No Minimum OA ResetWith the 0-30% OA Damper arrangement, the Minimum Outdoor Damper Position Reset Flag can only be set to “None”. The dampers are always control to the Minimum Outdoor Damper Position Set Point except as noted in the previous section when they are continuously driven to 0%.Network OA ResetWhen the Minimum Outdoor Damper Position Reset Flag is set to “None”, the Minimum Outdoor Damper Position Set Point can be reset between 0-30% via a network signal.

100% Outdoor Air Damper ControlWhen a unit is equipped with a 100% outdoor air hood, the outdoor air dampers are driven open continuously whenever the unit enters the Startup operating state. If they are not open (above 50%) at the end of the Startup operating state or any time afterward while the fans are running, the unit is shutdown on the OA Dmpr Stuck fault. When the unit is shut down, the dampers remain open for 30 seconds after the unit airflow switch opens up indicating loss of airflow.

Note: The dampers remain open in the event that the air-flow switch does not open after the fans are shut down.

EconomizerTemperature Control

Entering Econo Operating StateIf a unit is equipped with a 0-100% modulating economizer, and economizer operation is available (refer to “Economizer Changeover Method” on page 71) the unit attempts to satisfy the cooling load by using outdoor air before using mechani-cal cooling. When this is the case, the unit enters the Econo operating state when the Ctrl Temp= value rises above the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band.

Note: Unless it is set by a signal from an optional space temperature sensor, the Effective Cooling Enable Set Point is set by the controller equal to the Cool-ing Enable Set Point.



Menu Name Item Name

Zone Cooling




Discharge Cooling

Eff Clg Spt= ___ ºF Effective Discharge Cooling Set Point

Clg Db= 1.0 ºF Discharge Cooling Dead Band

Min Clg Spt= 55.0 ºF Minimum Discharge Cooling Set Point

Max Clg Spt= 65.0 ºF Maximum Discharge Cooling Set Point

Zone Temp Setup

Clg Propbd= 8.0ºF Zone Cooling Propor-tional Band

Clg IntTime= 700 sec Zone Cooling Integral Time

Period= 60 sec Zone Control Period

Compressor Setup Stage Timer= 5 min Cooling Interstage Timer

Economizer Setup

Clg Propbd= 30.0 ºF Economizer Cooling Proportional Band

Clg IntTime= 100 sec Economizer Cooling Integral Time

Clg Period= 30 sec Economizer Cooling Period

70 McQuay OM 138-3

There are two processes involved in the Economizer control function. The first is the process of modulating the outdoor air dampers to maintain the Effective Discharge Cooling Set Point. The second is the process of adjusting the Effective Discharge Cooling Set Point up and down between the Mini-mum Discharge Cooling Set Point and the Maximum Dis-charge Cooling Set Point as the Ctrl Temp= value varies above and below the Effective Cooling Enable Set Point. The following sections describe these two processes.

Economizer Damper Modulation. When the Disch Air= value rises above the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band, the outdoor damper position is increased. When the Disch Air= value falls below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band, the outdoor damper position is decreased. The controller uses three PID control loop parameters to modulate the economizer dampers as the discharge air tem-perature changes. Theses are the Economizer Cooling Pro-portional Band, Economizer Cooling Integral Time and Economizer Cooling Period. Although these parameters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 107.

Effective Discharge Cooling Set Point Adjustment. When the Ctrl Temp= value rises above the Effective Cool-ing Enable Set Point by more than half the Cooling Enable Dead Band, the Effective Discharge Cooling Set Point is decreased. When the Ctrl Temp= value falls below the Effec-tive Cooling Enable Set Point by more than half the Cooling Enable Dead Band, the Effective Discharge Cooling Set Point is increased.

Note: When the unit first enters the Econo operating state, the Effective Discharge Cooling Set Point is set to the current Disch Temp= value.

The controller uses three PID control loop parameters to raise and lower the Effective Discharge Cooling Set Point as the Ctrl Temp= value changes. These are the Zone Cooling Proportional Band, Zone Cooling Integral Time and Zone Control Period. Although these parameters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 107.Economizer to Cooling Operating StateThe transition from the Econo to Cooling operating state occurs when the economizer is unable to satisfy the cooling load and mechanical cooling is available. Normally, this occurs when the OA Damper Pos= parameter indicates more than 95% open and the discharge air temperature is above the Effective Discharge Cooling Set Point by more than half

the Discharge Cooling Dead Band for longer than the Cool-ing Interstage Timer.To allow for the transition from the Econo to Cooling operat-ing state in the event the outdoor air dampers get stuck or there is a problem with the damper actuator feedback circuit and the OA Damper Pos= parameter does not reach 95%, the controller continually estimates the position of the dampers. This estimate is based on the accumulative damper drive open versus drive close time compared to the nominal stroke of the actuator. If the controller position estimate reaches 100% open and the discharge air temperature is above the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band for longer than the Cooling Interstage Timer, the unit makes the transition from the Econo to Cooling operating state regardless of the current OA Damper Pos= parameter indication.If economizer operation becomes disabled while the unit is in the Econo operating state, the transition from the Econo to Cooling operating state occurs. The outdoor air dampers are driven to the Effective Minimum Outdoor Damper Position Set Point (refer to “Minimum Ventilation Control” on page 72).Econo to Fan Only Operating StateThe unit will leave the Econo operating state and enter the Fan Only operating state when the Ctrl Temp= value falls below the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band and either of the follow-ing are true:1. The economizer damper position, as indicated by the

OA Damper Pos= parameter in the OA Damper menu, indicates that the dampers have been at the Effective Minimum Outdoor Damper Position Set Point for one Cooling Interstage Timer period.

2. The Effective Discharge Cooling Set Point has been at the Maximum Discharge Cooling Set Point for one Cooling Interstage Timer period.

The unit will also leave the Econo operating state and enter the Fan Only operating state if all cooling is disabled for any reason. Refer to “Clg Status” on page 45.

Economizer Changeover Method


Keypad/Display ID

Parameter NameMenu Name Item Name

OA Damper

EconChgovr= Enthalpy Economizer Changeover Flag

EconChgovrT= 60 ºF Economizer Changeover Set Point

EconChgovrDiff= 1ºF Economizer Changeover Differential

McQuay OM 138-3 71

There are three methods of determining whether or not the outdoor air is suitable for free cooling. Two of them sense enthalpy (dry bulb temperature and humidity) and one senses outdoor air dry bulb temperature only.Enthalpy ChangeoverThe two optional enthalpy changeover methods use external control devices. One device compares the outdoor air enthalpy with a set point; the other compares the outdoor air enthalpy with the return air enthalpy. All units with econo-mizers are at least equipped with the outdoor air enthalpy version. The comparative version is optional. In either case a binary input (MCB-BI11) is delivered to the controller indi-cating whether or not outdoor air is suitable for free cooling. When the outdoor air is suitable for free cooling (MCB-BI11 on), the OA Ambient= parameter indicates “Low” and the economizer operates as described in “Economizer” on page 70. When the outdoor air is not suitable for free cooling (MCB-BI11 off), the OA Ambient= parameter indicates “High” and economizer operation is disabled.To use either of these enthalpy methods, the Economizer Changeover Flag must be set to “Enthalpy.” In this case, the Economizer Changeover Set Point is ignored. For detailed information regarding the external enthalpy controls, refer to the “Unit Options” section of the model-specific installation manual (refer to Table 1 on page 3).Dry Bulb Temperature ChangeoverWhen a unit is equipped with an economizer, an internal dry-bulb temperature changeover strategy can be selected. When this method is selected, the controller compares the OA Temp= value to the Economizer Changeover Set Point. The enthalpy control input is ignored in this case.To use the dry bulb method, the Economizer Changeover Flag must be set to “Dry Bulb.” The controller then uses the Economizer Changeover Set Point to determine whether or not outdoor air may be used for cooling. If the OA Temp= value is less than or equal to this set point, economizer cool-ing is enabled (OA Ambient= parameter indicates “Low”). If the OA Temp= value rises above this set point by more than the Economizer Changeover Differential, economizer cool-ing is disabled (OA Ambient= parameter indicates “High”) and the outdoor air dampers are driven to the Effective Mini-mum Outdoor Damper Position Set Point (refer to “Mini-mum Ventilation Control” on page 72).

Minimum Ventilation Control

During normal occupied operation, the outdoor air dampers are prevented from closing below the Effective Minimum Outdoor Damper Position Set Point. This is to ensure that a minimum amount of ventilation air is always supplied to the space.

Note: During the Off, Startup, Recirc, and MWU operat-ing states, the Effective Minimum Outdoor Damper Position Set Point is set to 0%.



Menu Name Item Name

OA Damper

Eff Min OA Pos= ___%Effective Minimum Outdoor Damper Position Set Point

MinOA Type= NoneMinimum Outdoor Damper Position

Reset Flag

DesingFlow= No DesignFlow Flag

MinOA Pos= 10%Minimum Outdoor

Damper Position Set Point

MinOA Flow= 2000 CFM Minimum Outdoor Airflow Set Point

MinOA @Max Sig=50%

Outdoor Damper Position Set Point at Maximum External

Signal

Min Signal= 0% Minimum External OA Reset Signal

Max Signal= 100% Maximum External OA Reset Signal

MinOA ResetMax= 50%

Effective Minimum Outdoor Damper Position Set Point

Maximum Limit

Max Fan Diff= 50% Maximum Fan Capacity Differential

Min Fan Diff= 20% Minimum Fan Capacity Differential

Reset T Limit= 0°F OA Reset Tempera-ture Limit

DesignFlow Setup

Wait Time= 30 sec DesignFlow Wait Time

Modband= 50% DesignFlow Modula-tion Band

Max Step= 5% DesignFlow Maxi-mum Step

Deadband= 6% DesignFlow Dead-band

72 McQuay OM 138-3

The Effective Minimum Outdoor Damper Position Set Point can be reset between the Minimum Outdoor Damper Posi-tion Set Point and the Effective Minimum Outdoor Damper Position Set Point Maximum Limit in a number of ways. These are described as follows:Unoccupied OperationWhenever the unit is operating in the unoccupied operating states UnocEcon, UnocClg, or UnocHtg, the Effective Mini-mum Outdoor Damper Position Set Point is set to 0%.No Minimum OA ResetWhen the Minimum Outdoor Damper Position Reset Flag is set to “None” and the DesignFlow Flag is set to “No”, the Effective Minimum Outdoor Damper Position Set Point is set equal to the Minimum Outdoor Damper Position Set Point.External OA ResetThe Effective Minimum Outdoor Damper Position Set Point can be reset via a field supplied analog voltage or current signal. This signal can be in the range of 0-10 VDC or 0-20 mA. When the Minimum Outdoor Damper Position Reset Flag is set to “Ext V” or “Ext mA”, the Effective Minimum Outdoor Damper Position Set Point varies linearly between the Minimum Outdoor Damper Position Set Point and the Outdoor Damper Position Set Point at Maximum External Signal as the field voltage or current signal varies between a minimum and maximum (or maximum and minimum) value.The range and type of field reset signal is configured using the Minimum External OA Reset Signal and the Maximum External OA Reset Signal and setting a jumper on the main control board associated with analog input MCB-AI07. The analog input jumper is placed in either the “voltage” or “cur-rent” position. When the jumper is in the “voltage” position, the range of the input signal can be from 0-10 VDC and when in the “current” position, 0-20 mA. The input range is scaled using the Minimum External OA Reset Signal and the Maximum External OA Reset Signal parameters. If for example, the field signal is to be 1-5 VDC, the Minimum External OA Reset Signal must be set to 10% since 1 VDC is 10% of the 0-10 VDC range. The Maximum External OA Reset Signal must be set to 50% since 5 VDC is 50% of the 0-10 VDC range.

Note: The previous example demonstrated “direct acting” reset where the Effective Minimum Outdoor Damper Position Set Point increases as the voltage or current signal increases. “Reverse acting” reset can be accomplished as well. In the previous exam-ple, if instead the Minimum External OA Reset Sig-nal were set to 50% and the Maximum External OA Reset Signal where set to 10%, then the Effective Minimum Outdoor Damper Position Set Point would decrease as the voltage or current signal increases.

Refer to “External Outdoor Air Damper Reset Signal” in the “Field Wiring” section of IM 696, MicroTech II Applied Rooftop Unit Controller.

Note: The Minimum Outdoor Damper Position Reset Flag automatically reverts to “None” if the Design-Flow= parameter is set to “Yes”. This means the external OA reset and Design Flow cannot be used at the same time.

Network OA ResetWhen the Minimum Outdoor Damper Position Reset Flag is set to “None” and the DesignFlow Flag is set to “No”, the Effective Minimum Outdoor Damper Position Set Point is set equal to the Minimum Outdoor Damper Position Set Point. The Minimum Outdoor Damper Position Set Point can then be set via a network signal to meet the outdoor air requirements. DesignFlow OA Airflow Measurement ResetWhen a unit is equipped with the optional DesignFlow out-door air measuring system and the DesignFlow Flag is set to “Yes”, the Effective Minimum Outdoor Damper Position Set Point is adjusted based on the measured amount of outdoor air being brought into the unit. If that airflow is below the desired value, the Effective Minimum Outdoor Damper Position Set Point is increased and if that airflow is above the desired value, Effective Minimum Outdoor Damper Position Set Point is decreased. The Effective Minimum Outdoor Damper Position Set Point is limited between the Minimum Outdoor Damper Position Set Point and the Effective Mini-mum Outdoor Damper Position Set Point Maximum Limit.

Note: The DesignFlow Flag can be set to “Yes” only when the unit is configured with the optional DesignFlow outdoor air measurement feature.

Note: The Minimum Outdoor Damper Position Reset Flag automatically reverts to “None” if the Design-Flow= parameter is set to “Yes.”

The current outdoor air for each of the two OA inlets is determined by comparing the resistance of the right and left airflow monitoring devices (input to MCB-AO7 and MCB-AO8 respectively). These resistances are compared to tabu-lated airflow data. The two CFM values are added together to determine the Current Flow (OA Flow=) value.At increments equal to the DesignFlow Wait Time, a Step Value is calculated. If the Flow Ratio (the ratio of the Cur-rent Flow to the Minimum Outdoor Airflow Set Point multi-plied by 100%) is greater than 100% by more than half of the DesignFlow Deadband, the Effective Minimum Outdoor Damper Position Set Point is decreased by the Step Value. If the Flow Ratio is less than 100% by more than half of the DesignFlow Deadband, the Effective Minimum Outdoor Damper Position Set Point is increased by the Step Value.

McQuay OM 138-3 73

The Step Value is determined using the smaller of the fol-lowing two calculations:

Or

Where:

The two OA airflow inputs to the controller from the Design-Flow stations are in the form of 0-5 VDC signals. The cur-rent magnitude of these inputs can be read via the LH LvlPos= (left-hand assembly, opposite the main control panel) and RH LvlPos= (right-hand assembly, control panel side) parameters on the unit keypad/display. These parame-ters read 00.00% to 100.00% as the corresponding input var-ies from 0-5 VDC and are used in the initial field leveling procedure required at unit startup. For leveling details, refer to the applicable model specific installation and maintenance manual (refer to Table 1 on page 3). The DesignFlow assem-blies are factory calibrated such that these inputs should be 1 VDC (LH LvlPos= or RH LvlPos= 20.00%) when the DesignFlow assembly is in the 0 airflow position. If either input ever drops below 0.9 VDC (LH LvlPos= or RH Lvl-Pos= 18.00%) the keypad OA Flow= parameter reads 1 CFM, indicating the value is out of range. This is an indica-tion that one, or both assemblies, require service.Discharge/Return Fan Differential OA ResetWhen a unit is equipped with return air fan inlet vanes or a return fan VFD, it may be necessary to increase the amount of outdoor air if the difference between the discharge and return fan capacity gets to large. If this is not done the dis-charge air fan can potentially be “starved” for air. A dis-charge fan operating in a “starved” condition not only has difficulty meeting the system airflow requirements but may cause excessive vibration and/or damage to damper sets and/or the return fan motor or VFD. To overcome this type of problem, the MicroTech II unit controller provides a dis-charge/return fan differential OA reset strategy, which auto-matically resets the Effective Minimum Outdoor Damper Position Set Point as the difference between the discharge and return air fan capacity varies.

Note: The discharge fan capacity is always assumed to be 100% on a zone (or space comfort) control unit.

The discharge/return fan OA reset strategy is automatically used when the difference between the discharge and return fan capacity exceeds the Minimum Fan Capacity Differen-tial. When the difference is less than or equal to the Mini-mum Fan Capacity Differential, the Effective Minimum Outdoor Damper Position Set Point is set to the Minimum Outdoor Damper Position Set Point (unless it is reset higher by another one of the reset methods). As the fan differential varies between the Minimum Fan Capacity Differential and the Maximum Fan Capacity Differential, the Effective Mini-mum Outdoor Damper Position Set Point is reset between the Minimum Outdoor Damper Position Set Point and the Effective Minimum Outdoor Damper Position Set Point Maximum Limit.OA Reset OverrideUnder some conditions the discharge air can contain a high percentage of outdoor air when any of the available OA reset features are active. If the outdoor air is very cold, the dis-charge air could also become very cold, particularly if the unit is equipped with no heat. Therefore, very cold discharge temperatures could result unless some other provision is made for tempering the air. If no other provisions are avail-able for tempering the air it may be necessary to override the outdoor air reset strategy if the discharge air becomes to cold.To allow for such a contingency, the MicroTech II controller is equipped with an OA Reset Temperature Limit. If the dis-charge air temperature drops below this adjustable limit by more than half the Clg Db= parameter in the Discharge Cooling menu, any of the OA reset functions (with the exception of the discharge/return fan differential OA reset function) are overridden and the Effective Minimum Out-door Damper Position Set Point is reset to maintain the dis-charge air temperature at this limit.

Note: This temperature override function is disabled when the OA Reset Temperature Limit is set to 0°F and when the unit is in the Cooling operating state.

Once the OA reset override function is active, normal con-trol resume as follows:1. If the Minimum Outdoor Damper Position Reset Flag is

set to “Ext mA” or “Ext V”, normal control resumes if the Effective Minimum Outdoor Damper Position Set Point is more than 2% above the calculated position based on the external OA reset function for more than two minutes. Refer to “External OA Reset” on page 73.

2. If the DesignFlow Flag is set to “Yes”, normal control resumes if the Flow Ratio exceeds 100% by more than half the DesignFlow Deadband for more than two min-utes. Refer to “DesignFlow OA Airflow Measurement Reset” on page 73.

Step Value DesignFlow Maximum Step=

Step Value (Error) DesignFlow Maximum StepDesignFlow Modulation Band-------------------------------------------------------------------------=

Error Absolute Value of 100% Flow Ratio–=

74 McQuay OM 138-3

Cooling: MultistageTemperature Control

Entering Cooling Operating StateThe unit enters the Cooling operating state from the Recirc or Fan Only operating state when the Ctrl Temp= value rises above the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band and economizer opera-tion is not available. The unit enters the Cooling operating state from the Econo operating state as describe in “Econo-mizer to Cooling Operating State” on page 71.When the unit is in the Cooling operating state, cooling stages are turned on and off to maintain the Ctrl Temp= value at the Effective Cooling Enable Set Point.

Note: Unless it is set by a signal from an optional space temperature sensor, the Effective Cooling Enable Set Point is set by the controller equal to the Cool-ing Enable Set Point.

The controller activates the first stage of mechanical cooling as it enters the Cooling operating state. When the Ctrl

Temp= value is above the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band and the Cooling Interstage Timer has expired since the last stage change, cooling capacity is increased by one stage. When the Ctrl Temp= value is below the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band and the Cooling Interstage Timer has expired since the last stage change, cooling capacity is decreased by one stage.

Discharge Temperature Override. While controlling the Ctrl Temp= value to the Effective Cooling Enable Set Point, the controller places a low limit on the discharge air temperature. The controller does not allow the Disch Temp= value to fall below the Minimum Discharge Cooling Set Point without taking action. If the Disch Temp= value falls below the Minimum Discharge Cooling Set Point, cooling capacity is decreased by one stage (subject to the Cooling Interstage Timer).Cooling to Econo Operating StateThe unit will transition from the Cooling to Econo operating state when either of the following are true:1. Economizer operation is available and compressor oper-

ation be comes disabled as describe in “Low Ambient Cooling Lockout“ below.

2. The Ctrl Temp= value is below the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band, economizer operation is available and the cooling capacity is at 0% for more than the Cooling Interstage Timer period.

Cooling to Fan Only Operating StateThe unit will transition from the Cooling to Fan Only operat-ing state when any of the following are true:1. Compressor operation is disabled as described below in

“Low Ambient Cooling Lockout“ and economizer oper-ation is not available.

2. The Ctrl Temp= value is below the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band, economizer operation is not available and the cooling capacity is at 0% for more than the Cooling Interstage Timer period.

3. All cooling is disabled for any reason. Refer to “Clg Sta-tus” on page 45.



Menu Name Item Name

Zone Cooling




Discharge Cooling

Min Clg Spt= 55.0 ºFMinimum Dis-

charge Cooling Set Point

Max Clg Spt= 65.0 ºFMaximum Dis-

charge Cooling Set Point

Compressor SetupClg Method= Average Discharge Cooling

Method Flag

Stage Time= 5 min Cooling Interstage Timer

McQuay OM 138-3 75

Low Ambient Cooling Lockout

Mechanical cooling is disabled when the outdoor air temper-ature is below the Low Ambient Cooling Lockout Set Point. When this occurs, the Clg Status= parameter indicates either “Econo” or “Off Amb” if all cooling is not disabled for some other reason. When the outdoor air temperature rises above the Low Ambient Cooling Lockout Set Point by more than the Low Ambient Cooling Lockout Differential, compres-sorized cooling is re-enabled. The Clg Status= parameter indicates either “All Clg” or “Mech Clg” if all cooling is not disabled for some other reason.

Note: If the unit is equipped with an evaporative con-denser section, the Low Ambient Cooling Lockout Set Point cannot be set below 40°F.

Note: Unless the unit is equipped with the SpeedTrol low ambient condenser fan control option, the Low Ambient Cooling Lockout Set Point should never be set below 45°F.

Compressor Staging

On units equipped with compressorized cooling, there are many different compressor staging configurations available, depending upon unit size. For specific output staging infor-mation for the possible configurations, refer to the “Cooling Control Boards (CCB1, CCB2 or GCB1)” section of IM 696, MicroTech II Applied Rooftop Unit Controller.In most cases the unit can be configured to either cross-load the two cooling circuits or to stage up one circuit before the other. In either case, when possible, compressors are staged up and down to equalize run hours. Also, in most of the available unit staging configurations, circuit # 1 or circuit #2 can be designated as the “lead” circuit or the unit can be set for automatic “lead/lag” of the circuits. The circuit lead/lag,

cross-circuit loading and lead-circuit loading functions are described in the following sections.Circuit Lead/Lag4 Compressors/4 Stages or 6 Compressors/6 Stages. The “lead” refrigeration circuit can be selected by setting the Circuit Lead/Lag Flag. When the Circuit Lead/Lag Flag is set to “Auto”, the “lead” refrigeration cir-cuit alternates each time cooling is staged down until all the compressors are off. The refrigeration circuit with the com-pressor with the fewest run hours becomes the “lead.”When the Circuit Lead/Lag Flag is set to “#1”, circuit #1 always acts as the “lead.” When the Circuit Lead/Lag Flag is set to “#2”, circuit #2 always acts as the “lead.”

Note: Automatic lead/lag or circuit #2 lead operation should not be used if the unit is equipped with the hot gas bypass option on circuit #1 only.

2 Compressors/3 Stages or 3 Compressors/4 Stages. Circuit lead/lag operation does not apply to these staging configurations and the Circuit Lead/Lag Flag has no affect on the unit operation.

2 Compressors/4 Stages, 2 Compressors/6 Stages, 4 Compressors/8 Stages. The “lead” refrigeration cir-cuit can be selected by setting the Circuit Lead/Lag Flag. When the Circuit Lead/Lag Flag is set to “Auto”, the “lead” refrigeration circuit alternates each time cooling is staged down until all compressors are off. The refrigeration circuit with the lower run hours then becomes the “lead.” When the Circuit Lead/Lag Flag is set to “#1” circuit #1 always acts as the “lead.” When the Circuit Lead/Lag Flag is set to “#2” circuit #2 always acts as the “lead.”

Note: In these cooling staging configurations, circuit #1 run hours are considered equal to the run hours of compressor #1 and circuit #2 run hours are consid-ered equal to the run hours of compressor #2.

Note: Automatic lead/lag or circuit #2 lead operation should not be used if the unit is equipped with the hot gas bypass option on circuit #1 only.

Cross Circuit LoadingWhen the Circuit Staging Method Flag is set to “Cross Circ”, the two circuits are loaded and unloaded as evenly as possi-ble. There are some differences in “Cross Circuit” staging method depending on the unit compressor stage configura-tion.

4 Compressors/4 Stages or 6 Compressors/6 Stages. When a capacity increase is required and the num-ber of operating compressors in both circuits is the same, the compressor in the “lead” circuit with the fewest run hours that is not operating is turned on. When a capacity increase is required and the number of compressors in the two circuits is not the same, the compressor with the fewest run hours in the circuit with the fewest operating compressors is turned on.



Menu Name Item Name

Zone Cooling

OATClg Lock= 55.0 ºF Low Ambient Cooling Lockout Set Point

OATLock Diff= 3.0°FLow Ambient Cooling Lockout Set Point Dif-

ferential



Menu Name Item Name

Compressor SetupLead Circuit= # 1 Circuit Lead/Lag Flag

CompCtrl= Cross Circ Circuit Staging Method Flag

76 McQuay OM 138-3

When a capacity decrease is required and the number of operating compressors in both circuits is the same, the oper-ating compressor with the highest run hour total in the “lag” circuit is turned off. When a capacity decrease is required and the number of operating compressors in the two circuits is not the same, the operating compressor with the most run hours in the circuit with most operating compressors is turned off.

Note: A disabled circuit remains at zero capacity. If the other circuit is enabled, the circuit capacity is con-trolled similar to the Lead-Loading method.

2 Compressors/4 Stages, 2 Compressors/6 Stages or 4 Compressors/8 Stages. When a capacity increase is required, the circuit operating at the lower capacity is staged up. If both circuits are operating at the same capacity, the “lead” circuit is staged up if not already at its maximum.When a capacity decrease is required, the circuit operating at the higher capacity is staged down. If both circuits are oper-ating at the same capacity, the “lag” circuit is staged down.

Note: A disabled circuit remains at zero capacity. If the other circuit is enabled, it acts as the “lead” and the circuit capacity is controlled similar to the Lead-Loading method.

2 Compressors/3 Stages. With this staging configura-tion, the compressors are always controlled in the same way. There are no circuit “lead/lag”, “compressor run hour” or “Cross Circuit” variations to the staging sequence. Starting with 0% capacity, when a capacity increase is required, the “small” compressor on circuit #1 is turned on. When a fur-ther increase is required, the “large” compressor on circuit # 2 is turned on and the “small” compressor on circuit #1 is turned off. For the final capacity increase, the “small” com-pressor on circuit #1 is turned on while the “large” compres-sor on circuit #2 remains on.

Note: If the “small” compressor on circuit #1 is disabled, the “large” compressor on circuit # 2 operates when cooling is required and the cooling capacity is set to 66%. If the “large” compressor on circuit # 2 is dis-abled, the “small” compressor on circuit # 1 oper-ates when cooling is required and the cooling capacity is set to 33%.

3 Compressors/4 Stages. With this staging configuration, the compressors are always controlled in the same way. There are no circuit “lead/lag” or “cross circuit” variations to the staging sequence.Starting with 0% cooling capacity, when a capacity increase is required, the small compressor on circuit #1 with the few-est run hours is turned on (25%). When a further capacity increase is required, the remaining compressor on circuit #1 is turned on (50%). When a further capacity increase is required, the large compressor on circuit #2 is turned on and

the small compressor on circuit #1 with the most run hours is turned off (75%). When a further capacity increase is required, the small compressor on circuit #1 that is not oper-ating is turned on (100%). Starting with 100% capacity, when a capacity decrease is required, the small compressor on circuit #1 with the most run hours is turned off (75%). When a further capacity decrease is required, the large compressor on circuit #2 is turned off and the small compressor on circuit #1 that is not operating is turned on (50%). When a further capacity decrease is required, the small compressor on circuit #1 with the most run hours is turned off (25%). When a further capacity decrease is required, the operating small compres-sor on circuit #1 is turned off (0%).

Note: If one of the “small” compressors on circuit #1 is disabled, the unit stages between 25% (using the enabled “small” compressor on circuit #1) and 75% (“small” compressor on circuit #1 and “large” com-pressor on circuit #2) skipping the 50% capacity step. If both of the “small” compressors on circuit #1 are disabled, the “large” compressor on circuit #2 (50% capacity) would cycle on and off to main-tain the load. If the “large” compressor on circuit #2 is disabled, the two “small” compressors on circuit #1 would cycle on and off (based on run hours) to maintain the load.

Lead Circuit LoadingWhen the Circuit Staging Method Flag is set to “Lead Load”, one circuit is loaded completely before the first compressor in the second circuit is turned on, and one circuit is unloaded completely before the other circuit begins to be unloaded. There are some differences in “Lead Load” staging method depending on the unit compressor stage configuration.

4 Compressors/4Stages or 6 Compressors /6Stages. When a capacity increase is required and the number of operating compressors is 0, the compressor in the “lead” circuit with the fewest run hours is turned on. When a capacity increase is required, the “lead” circuit is staged up if not already fully loaded. If the “lead” circuit is fully loaded, the compressor in the “lag” circuit with the fewest run hours is turned on. When a further capacity increase is required, the “lag” circuit is staged up. When a capacity decrease is required, the operating compressor in the “lag” circuit with the most run hours is turned off. This continues until the “lag” circuit is fully unloaded. When a further capacity decrease is required, the operating compressor in the “lead” circuit with the most run hours is turned off. This continues until the “lead” circuit is fully unloaded.

Note: A disabled circuit remains at zero capacity. If the other circuit is enabled, it acts as the “lead” and the circuit capacity is controlled using the Lead-Load-ing method.

McQuay OM 138-3 77

2 Compressors/4 Stages, 2 Compressors/6 Stages or 4 Compressors/8 Stages. When a capacity increase is required and the “lead” circuit is not at maximum, the “lead” circuit is staged up. When a capacity increase is required and the “lead” circuit is already at its maximum, the “lag” circuit is staged up. When a capacity decrease is required and the “lag” circuit is not at zero capacity, the “lag” circuit is staged down. When a capacity decrease is required and the “lag” circuit is at zero capacity, the “lead” circuit is staged down.

Note: A disabled circuit remains at zero capacity. If the other circuit is enabled, it acts as the “lead” and the circuit capacity is controlled using the Lead-Load-ing method.

2 Compressors/3 Stages. With this staging configura-tion, the compressors are always controlled in the same way. There are no circuit “lead/lag”, “compressor run hour” or “Lead Load” variations to the staging sequence. Starting with 0% capacity, when a capacity increase is required, the “small” compressor on circuit #1 is turned on. When a fur-ther increase is required, the “large” compressor on circuit #2 is turned on and the “small” compressor on circuit #1 is turned off. For the final capacity increase, the “small” com-pressor on circuit #1 is turned on while the “large” compres-sor on circuit #2 remains on.

Note: If the “small” compressor on circuit #1 is disabled, the “large” compressor on circuit #2 operates when cooling is required and the cooling capacity is set to 66%. If the “large” compressor on circuit #2 is dis-abled, the “small” compressor on circuit #1 oper-ates when cooling is required and the cooling capacity is set to 33%.

Generic Condensing Unit StagingWhen a unit is equipped with a DX cooling coil and is inter-faced with a field supplied condensing unit, it is equipped with a generic condenser control board (GCB1) for control-ling the cooling stages on the condensing unit. In this case, circuit lead/lag, cross-circuit loading and lead-circuit loading are not applicable. The outputs on the condenser control board (GCB1) are simply staged up and down sequentially as the cooling capacity changes.

Air-Cooled Condenser Fan Control

On units equipped with compressorized cooling and an air-cooled condensing section, there are up to four steps of con-denser fan operation per cooling circuit depending on the size of the unit. The fans in each circuit are started and stopped based on outdoor air temperature when circuit is operating. The first condenser fan step in each operating cir-cuit is turned on when the OA Temp= value rises above the First Condenser Fan Set Point and is turned off when the OA Temp= value falls below the First Condenser Fan Set Point by more than the Condenser Fan Differential. The second condenser fan step in each operating circuit is turned on when the OA Temp= value rises above the Second Con-denser Fan Set Point and is turned off when the OA Temp= value falls below the Second Condenser Fan Set Point by more than the Condenser Fan Differential. The third con-denser fan step in each operating circuit is turned on when the OA Temp= value rises above the Third Condenser Fan Set Point and is turned off when the OA Temp= value falls below the Third Condenser Fan Set Point by more than the Condenser Fan Differential. The fourth condenser fan step in each operating circuit is turned on when the OA Temp= value rises above the Fourth Condenser Fan Set Point and is turned off when the OA Temp= value falls below the Fourth Condenser Fan Set Point by more than the Condenser Fan Differential.The condenser fan set points must be set to specific values that depend on the unit model sized according to Table . (R22) or 41 (R407).



Menu Name Item Name

Compressor Setup

Cond Fan1 Spt= 0°F First Condenser Fan Set Point

Cond Fan2 Spt= 55°F Second Condenser Fan Set Point

Cond Fan3 Spt= 65°F Third Condenser Fan Set Point

Cond Fan4 Spt= 75°F Fourth Condenser Fan Set Point

Cond Fan Diff= 5°F Condenser Fan Dif-ferential

78 McQuay OM 138-3

Evaporative Condenser Control

When a unit is equipped with an evaporative condensing section, the control of this section consists of circulating water from a sump below the condenser tubes to nozzles above the condenser coil and cycling condenser fans based on the sump water temperature.

Table 40: Condenser Fan Ambient Setpoints - Units with R22 Refrigerant

UnitSize

Cond. Fan # 1

Setpoint(°F)

Cond. Fan # 2

Setpoint(°F)

Cond. Fan # 3

Setpoint(°F)

Cond. Fan # 4

Setpoint(°F)

015 0 60 NA NA018 0 60 NA NA020 0 60 NA NA025 0 65 NA NA030 0 65 NA NA036 0 70 NA NA040 0 65 NA NA045 0 65 NA NA050 0 60 NA NA060 0 25 70 NA070 0 40 70 NA075 0 65 75 0080 0 65 75 0090 0 65 75 0

105 (Recip) 0 0 58 70

105 (Scroll) 0 0 45 70

115 0 0 55 75125 0 65 35 80135 0 55 25 65

Table 41: Condenser Fan Ambient Setpoints - Units with R407 Refrigerant

UnitSize

Cond. Fan # 1

Setpoint(°F)

Cond. Fan # 2

Setpoint(°F)

Cond. Fan # 3

Setpoint(°F)

Cond. Fan # 4

Setpoint(°F)

015 0 60 NA NA018 0 0 NA NA020 0 0 NA NA025 0 65 NA NA030 0 65 NA NA036 0 65 NA NA040 0 60 NA NA045 0 55 NA NA050 0 50 NA NA060 0 15 70 NA070 0 30 70 NA075 0 65 75 0080 0 65 75 0

090 (Scroll) 0 50 75 0

090 (Recip) 0 65 75 0

105 (Scroll) 0 0 35 70

105 (Recip) 0 0 52 70

115 0 0 45 75125 0 55 30 80135 0 45 20 65



Menu Name Menu Item

Evap Condensing

Min Fan Speed= 25% Minimum Condenser Fan Speed

Min SumpT= 75°F Minimum Condenser Sump Temperature

Max SumpT= 85°F Maximum Condenser Sump Temperature

Sump Dump Spt= 35°F Sump Dump Set Point

Stage Time= 10 min Condenser Fan Stage Timer

Dolphin= No Dolphin Water Treat-ment Method Flag

McQuay OM 138-3 79

Depending on unit size, there can be up to three steps of condenser fan operation per circuit. Optionally, a VFD can be supplied that varies the speed of the first condenser fan on both cooling circuits based on sump water temperature. When the VFD option is provided, the VFD is controlled via a communication interface between the main control board and the VFD.The following sections describe the condenser fan control for units with and without an optional VFD, and the control of the sump water circulating pump.Condenser Fan Operation without VFDWhen the first compressor on the “lead” cooling circuit is turned on, condenser fan step one is turned on as soon as the Sump Temp= value rises above the Maximum Condenser Sump Temperature. The unit then stages up and down between condenser fans steps 0, 1, 2 and 3 as the Sump Temp= value changes. Because of the high humidity environment they operate in, all of the condenser fans need to run periodically. The controller accomplishes this by cycling the condenser fan steps based on fan operating hours. When increasing a step, the fan that has been off the longest is turned on first. When decreasing a step, the fan that has been on the longest is turned off first.If the Condenser Fan Stage Timer has expired since the last stage change and the Sump Temp= value rises above the Maximum Condenser Sump Temperature, the condenser fan step is increased. If the Condenser Fan Stage Timer has expired since the last stage change and the Sump Temp= value drops below the Minimum Condenser Sump Tempera-ture, the condenser fan step is decreased. When at least one compressor is operating on the both circuits, the condenser fan step on the “lag” circuit is set equal to that of the “lead” circuit so that the condensers fans on both circuits step up and down together.

Note: If the condenser fan operation steps to 0, it is not required that the Condenser Fan Stage Timer has expired before staging back up to step 1 when the Sump Temp= value rises again above the Maximum Condenser Sump Temperature.

Condenser Fan Operation with VFDWhen the evaporative condenser option includes a VFD, the condenser fan staging is similar to that describe above with the following exceptions:1. When the first compressor on the “lead” cooling circuit

is turned on, the first fan on both circuits (they are both controlled by the same VFD) are turned on immediately regardless of the Sump Temp= value and whether or not a compressor is running on the “lag” circuit.

2. When operating, the speed of the VFD varies linearly between the Minimum Condenser Fan Speed and 100% as the Sump Temp= varies between the Minimum Con-denser Sump Temperature and the Maximum Condenser Sump Temperature.

Evaporative Condenser Sump ControlWhen a unit is equipped with an evaporative condensing sec-tion, water is pumped from a sump beneath the condenser tubes to nozzles above the condenser coil that spray water onto the banks of condenser coil tubes. The controller starts the sump pump whenever the unit enters the Cooling operat-ing state by turning on a “cooling enable” output on the MCB (MCB-BO7). This output energizes a sump pump relay that in turn energizes the sump pump conductor. A low water switch monitors the water level in the sump. The pump remains running as long as this switch indicates an accept-able water level and the sump pump relay is energized.If the sump temperature gets too cold, the sump is emptied to prevent freezing. If the SumpTemp= value drops below the Sump Dump Set Point, output 8 on the cooling control boards (CCB1-B08 & CCB2-B08) are energized, opening the sump dump valve, emptying the sump. When the SumpTemp= value rises back above the Sump Dump Set Point by more than a fixed 3° F differential and the unit enters the Cooling operating state, the sump valve is closed allowing the sump to be refilled.If a Dolphin water treatment system is being employed in the field, the sump pump must be run every three days to reduce scaling. If the sump pump remains off for five days, the sump must be emptied. This would typically occur when the outdoor temperature remains below 35°F.When the Dolphin Water Treatment Method Flag is set to “Yes”:1. The sump pump is turned On for one hour if it has been

Off for more that 72 hours (but less than 120 hours), the OAT is greater than 35°F, and the sump dump outputs are Off.

2. The sump dump outputs (CCB1-BO8 and CCB2-BO8) are energized to empty the sump if the sump pump has been Off for more than 120 hours.

Circuit PumpdownNormal Circuit PumpdownDuring normal cooling circuit operation, the circuit is pumped down when the last compressor in the circuit is shut down due to normal staging. It is also pumped down if the entire circuit is shut down due to any alarms other than Hi Pres-Ckt1, Hi Pres-Ckt2, Comp #1 Alm, Comp #2 Alm, Comp #3 Alm, Comp #4 Alm, Comp #5 Alm and Comp #6 Alm.When pumdown is required for a circuit, the Liquid Line Solenoid Valve for that circuit is closed (output turned off) and a compressor on that circuit operates until the circuit low pressure switch opens at which time the compressor is turned off. If the low pressure switch does not open within 180 sec-onds, pumpdown is terminated by turning off the compressor and the PumpDown-Ckt1 (or PumpDown-Ckt2) problem alarm is generated.

80 McQuay OM 138-3

Manual Circuit PumpdownCompressors in a Circuit are Operating: Circuit pumpdown is manually initiated if the circuit pumpdown switch (PS1-Circuit #1 or PS2-Circuit #2) in the main control panel is placed in the Pumpdown (Off) position.

Compressors in a Circuit are not Operating: Circuit pumpdown is manually initiated if the circuit pumpdown switch (PS1-Circuit #1 or PS2-Circuit #2) is cycled from the Auto (On) to the Pumpdown (Off) position twice in less than 20 seconds and the low pressure switch is closed.When pumpdown is initiated for a circuit, the liquid line sole-noid valve for that circuit is closed (output turned off) and a compressor on that circuit operates until the circuit low pres-sure switch opens at which time the compressor is turned off. If the low pressure switch does not open within 180 seconds, pumpdown is terminated by turning off the compressor and the PumpDown-Ckt1 (or PumpDown-Ckt2) problem is generated.

Cooling: ModulatingTemperature Control

Entering Cooling Operating StateThe unit enters the Cooling operating state from the Recirc or Fan Only operating state when the Ctrl Temp= value rises above the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band and economizer opera-tion is not available. The unit enters the Cooling operating state from the Econo operating state as describe in “Econo-mizer to Cooling Operating State” on page 71.

Note: Unless it is set by a signal from an option space temperature sensor, the Effective Cooling Enable Set Point is set by the controller equal to the Cool-ing Enable Set Point.



Menu Name Item Name

Zone Cooling




Discharge Cooling

Eff Clg Spt= ___ ºF Effective Discharge Cooling Set Point


Min Clg Spt= 55.0 ºF Minimum Discharge Cooling Set Point

Max Clg Spt= 65.0 ºF Maximum Discharge Cooling Set Point

Zone Temp Setup

Clg Propbd= 8.0ºF Zone Cooling Propor-tional Band

Clg IntTime= 700 sec Zone Cooling Integral Time


Chilled Water Setup

Clg Propbd= 30.0 ºF Cooling Proportional Band

Clg IntTime= 100 sec Cooling Integral TimeClg Period= 30 sec Cooling Period

Stage Timer= 5 min Cooling Interstage Timer

McQuay OM 138-3 81

Chilled Water: Valve ControlWhen the unit is in the Cooling operating state, the chilled water valve is modulated to satisfy the cooling load. There are two processes involved in the chilled water valve control function. The first is the process of modulating the valve to maintain the Effective Discharge Cooling Set Point. The sec-ond is the process of adjusting the Effective Discharge Cool-ing Set Point up and down between the Minimum Discharge Cooling Set Point and the Maximum Discharge Cooling Set Point as the Ctrl Temp= value varies above and below the Effective Cooling Enable Set Point. The following sections describe these two processes.

Valve Modulation. When the Disch Air= value rises above the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band, the chilled water valve position is increased. When the Disch Air= value falls below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band, the chilled water valve position is decreased. The controller uses three PID control loop parameters to modulate the chilled water valve as the discharge air temper-ature changes. Theses are the Cooling Proportional Band, Cooling Integral Time and Cooling Period. Although these parameters can be adjusted, for most applications, the fac-tory default values for these parameters provide the best con-trol. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 107.


Note: When the unit first enters the Cooling operating state, the Effective Discharge Cooling Set Point is set to the current Disch Temp= value.

The controller uses three PID control loop parameters to raise and lower the Effective Discharge Cooling Set Point as the Ctrl Temp= value changes. These are the Zone Cooling Proportional Band, Zone Cooling Integral Time and Zone Control Period. Although these parameters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 107.Chilled Water: Face and Bypass Damper ControlWhen the unit is in the Cooling operating state, the chilled water valve is driven fully open and the face and bypass

dampers are modulated to satisfy the cooling load. There are two processes involved in the face and bypass damper con-trol function. The first is the process of modulating the dampers to maintain the Effective Discharge Cooling Set Point. The second is the process of adjusting the Effective Discharge Cooling Set Point up and down between the Mini-mum Discharge Cooling Set Point and the Maximum Dis-charge Cooling Set Point as the Ctrl Temp= value varies above and below the Effective Cooling Enable Set Point. The following sections describe these two processes.

Face and Bypass Damper Modulation. When the Disch Air= value rises above the Effective Discharge Cool-ing Set Point by more than half the Discharge Cooling Dead Band, the face and bypass dampers position is increased to the face. When the Disch Air= value falls below the Effec-tive Discharge Cooling Set Point by more than half the Dis-charge Cooling Dead Band, the face and bypass damper position is decreased to the face. The controller uses three PID control loop parameters to modulate the face and bypass dampers as the discharge air temperature changes. Theses are the Cooling Proportional Band, Cooling Integral Time and Cooling Period. Although these parameters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed information regarding tuning PID con-trol loop parameters, refer to “MicroTech II DDC Features” on page 107.


Note: When the unit first enters the Cooling operating state, the Effective Discharge Cooling Set Point is set to the current Disch Temp= value.

The controller uses three PID control loop parameters to raise and lower the Effective Discharge Cooling Set Point as the Ctrl Temp= value changes. These are the Zone Cooling Proportional Band, Zone Cooling Integral Time and Zone Control Period. Although these parameters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 107.

82 McQuay OM 138-3

Cooling to Econo Operating StateWhen economizer operation is available, the unit will leave the Cooling operating state and enter the Econo operating state when the Ctrl Temp= value falls below the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band and either of the following are true:1. The chilled water valve is closed for more than one

Cooling Interstage Timer period.2. The Effective Discharge Cooling Set Point has been at

the Maximum Discharge Cooling Set Point for one Cooling Interstage Timer period.

Cooling to Fan Only Operating StateWhen economizer operation is not available, the unit will leave the Cooling operating state and enter the Fan Only operating state when the Ctrl Temp= value falls below the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band and any of the following are true:1. The chilled water valve is closed for more than one

Cooling Interstage Timer period.2. The Effective Discharge Cooling Set Point has been at

the Maximum Discharge Cooling Set Point for one Cooling Interstage Timer period.

3. All cooling is disabled for any reason. Refer to “Clg Sta-tus” on page 45.

Heating: MultistageTemperature Control

Entering Heating Operating StateThe unit enters the Heating operating state from the Recirc or Fan Only operating state when the Ctrl Temp= value falls

below the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band. When the unit is in the Heating operating state, heating stages are turned on and off to maintain the Ctrl Temp= value at the Effective Heating Enable Set Point.

Note: Unless it is set by a signal from an option space temperature sensor or by the dehumidification func-tion, the Effective Heating Enable Set Point is set by the controller equal to the Heating Enable Set Point.

The controller activates the first stage of electric heat as it enters the Heating operating state. When the Ctrl Temp= value is below the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band and the Heat-ing Interstage Timer has expired since the last stage change, heating capacity is increased by one stage. When the Ctrl Temp= value is above the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band and the Heating Interstage Timer has expired since the last stage change, heating capacity is decreased by one stage.Discharge Temperature OverrideWhile controlling the Ctrl Temp= value to the Effective Heating Enable Set Point, the controller places limits on the discharge air temperature. The controller does not allow the Disch Temp= value to exceed the Maximum Discharge Heat-ing Set Point or fall below the Minimum Discharge Heating Set Point without taking action. If the Disch Temp= value exceeds the Maximum Discharge Heating Set Point, heating capacity is decreased by one stage (subject to the Heating Interstage Timer). If the Disch Temp= value falls below the Minimum Discharge Heating Set Point, heating capacity is increased by one stage (subject to the Heating Interstage Timer).Effective Discharge Heating Set Point LimitingOn units equipped with multistage electric heat, the Effective Discharge Heating Set Point is limited by a factory set 60°F maximum heater temperature rise limit. The controller does not allow the Effective Discharge Heating Set Point to be set higher than 60°F above the current temperature entering the discharge fan as indicated by the Ent Fan= parameter in the Temperatures menu.Heating to Fan Only Operating StateThe unit will transition from the Heating to Fan Only operat-ing state when either of the following are true1. The Ctrl Temp= value is above the Effective Heating

Enable Set Point by more than half the Heating Enable Dead Band and the heating capacity is a 0% for longer than the Heating Interstage Timer period.

2. Heating is disabled for any reason. Refer to “Htg Status” on page 46.



Menu Name Item Name

Zone Heating




Discharge HeatingMin Htg Spt= 55.0 ºF Minimum Discharge

Heating Set Point

Max Htg Spt= 65.0 ºF Maximum Discharge Heating Set Point

Heating Setup Stage Time= 5 Min Heating Interstage Timer

McQuay OM 138-3 83

Morning Warm-up Control

On return air units, morning warm up operation occurs after the transition from unoccupied to occupied mode when the Ctrl Temp= value is below the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band. Under these conditions, the controller enters the MWU oper-ating state after the normal startup sequence.


The MWU operating state is similar to the Heating operating state; the only difference is that the Eff Min OA Pos= param-eter is set to 0% during MWU. The unit remains in the MWU operating state until either the Ctrl Temp= value is equal to or greater than the Effective Heating Enable Set Point or the duration of the MWU operating state exceeds the Maximum Morning Warm-up Timer setting. In either case, since the Ctrl Temp= value has not risen above the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band when this occurs, the controller enters the Heating operating state.The Maximum Morning Warm-up Timer parameter is pro-vided to ensure that the required minimum ventilation air is being supplied after a known time regardless of the space temperature condition. For example, if actual occupancy is at 8:00 a.m. and unit startup is scheduled for 6:30 a.m., a Maxi-mum Morning Warm-up Timer setting of 90 minutes would ensure that the outdoor air dampers open to minimum posi-tion when building occupancy begins.

Note: The morning warm-up function does not occur on units equipped with 100% OA hoods.

High Ambient Heating Lockout

Heating is disabled when the outdoor air temperature is greater than the High Ambient Heating Lockout Set Point. When this occurs, the Htg Status= parameter in the System and Zone Heating menu indicates “Off Amb” if heating is not disabled for some other reason. When the outdoor air temperature drops below the High Ambient Heating Lockout Set Point by more than the High Ambient Heating Lockout Differential, heating operation is re-enabled.

Discharge Air Low Limit Control

If heating is enabled and there is no heating load (normally Fan Only operating state), the controller can activate the unit staged electric heating equipment as required to prevent the discharge air temperature from becoming too cool. It accom-plishes this by entering the Min DAT operating state when necessary.Entering Min DAT Operating StateWhen the Min DAT Control Flag is set to “Yes” and if the Disch Temp= parameter falls below the Minimum Discharge Temperature Limit by more than half the Discharge Heating Dead Band, the unit operating state changes from Fan Only to Min DAT. When in the Min DAT operating state, heating capacity is increased by one stage if the Disch Temp= parameter is below the Minimum Discharge Temperature Limit by more than half the Discharge Heating Dead Band (subject to the Heating Interstage Timer). Heating capacity is decreased by one stage if the Disch Temp= parameter rises above the Minimum Discharge Temperature Limit by more than half the Discharge Heating Dead Band (subject to the Heating Interstage Timer).



Menu Name Item Name

Zone Heating




Timer Settings Max MWU= 90 min Maximum Morning Warm-up Timer



Menu Name Item Name

Zone HeatingOATHtg Lock= 55.0°F High Ambient Heating

Lockout Set Point

OATLock Diff= 1.0°F High Ambient Heating Lockout Differential



Menu Name Item Name

Discharge Heating

Min DAT Ctrl= Yes Min DAT Control Flag

MinDAT Limit= 55.0 ºF

Minimum Discharge Temperature Limit

Htg Db= 1.0 ºF Discharge Heating Dead Band

84 McQuay OM 138-3

Leaving Min DAT Operating StateWhen the heating capacity has be 0% for one Heat Interstage Time period and the Disch Temp= parameter is above the Minimum Discharge Temperature Limit by more than half the Discharge Heating Dead Band, the unit leaves the Min DAT operating state and re-enters the Fan Only operating state.

Heating: ModulatingTemperature Control

Entering Heating Operating StateThe unit enters the Heating operating state from the Recirc or Fan Only operating state when the Ctrl Temp= value falls

below the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band.


There are several different modulating heating types avail-able with this equipment. There are some differences in the control sequence depending on the heat type installed. The different types are described in the following sections.Steam or Hot Water: Valve ControlWhen the unit is in the Heating operating state, the hot water or steam valve is modulated to satisfy the heating load. There are two processes involved in the heating valve con-trol function. The first is the process of modulating the heat-ing valve to maintain the Effective Discharge Heating Set Point. The second is the process of adjusting the Effective Discharge Heating Set Point up and down between the Mini-mum Discharge Heating Set Point and the Maximum Dis-charge Heating Set Point as the Ctrl Temp= value varies above and below the Effective Heating Enable Set Point. The following sections describe these two processes.

Valve Modulation. When the Disch Air= value falls below the Effective Discharge Heating Set Point by more than half the Discharge Heating Dead Band, the heating valve position is increased. When the Disch Air= value rises above the Effective Discharge Heating Set Point by more than half the Discharge Heating Dead Band, the heating valve position is decreased. The controller uses three PID control loop parameters to modulate the heating valve as the discharge air temperature changes. Theses are the Heating Proportional Band, Heating Integral Time and Heating Period. Although these parame-ters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 107.

Effective Discharge Heating Set Point Adjustment. When the Ctrl Temp= value rises above the Effective Heat-ing Enable Set Point by more than half the Heating Enable Dead Band, the Effective Discharge Heating Set Point is decreased. When the Ctrl Temp= value falls below the Effec-tive Heating Enable Set Point by more than half the Heating Enable Dead Band, the Effective Discharge Heating Set Point is increased.

Note: When the unit first enters the Heating operating state, the Effective Discharge Heating Set Point is set to the current Disch Temp= value.



Menu Name Item Name

Zone Heating


Occ Htg Spt= 70.0°F Heating Enable Set Point

Htg Deadband= 1.0°F Heating Enable Dead Band

Discharge Heating

Eff Htg Spt= ___°F Effective Discharge Heating Set Point

Htg Db= 1.0°F Discharge Heating Dead Band

Min Htg Spt= 55.0°F Minimum Discharge Heating Set Point

Max Htg Spt= 65.0°F Maximum Discharge Heating Set Point

Min DAT Ctrl= Yes Min DAT Control Flag

Min DAT Limit= 55.0°F Minimum Discharge Temperature Limit

Zone Temp Setup

Htg Propbd= 8.0°F Zone Heating Propor-tional Band

Htg IntTime= 700 sec Zone Heating Inte-gral Time


Heating Setup

Stage Timer= 5 min Heating Interstage Timer

F&BP Ctrl= OpenValve Face and Bypass Method Flag

F&BP Chgovr= 37°FFace and Bypass

Changeover Temper-ature

Htg Propbd= 30.0°F Heating Proportional Band

Htg IntTime= 100 sec Heating Integral Time

Htg Period= 30 sec Heating Period

McQuay OM 138-3 85

The controller uses three PID control loop parameters to raise and lower the Effective Discharge Heating Set Point as the Ctrl Temp= value changes. These are the Zone Heating Proportional Band, Zone Heating Integral Time and Zone Control Period. Although these parameters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 107.Steam or Hot Water Heat: Face and Bypass Damper Control-Open Valve MethodWhen a unit is equipped with steam or hot water with face and bypass damper heating there are two different methods available for controlling the heating arrangement. These are the “Open Valve” and “Modulating Valve” methods. This section describes the “Open Valve” method.When the Face and Bypass Method Flag is set to “Open-Valve”, the steam or hot water valve is driven fully open when the unit enters the Heating operating state. The face and bypass dampers are then modulated to satisfy the heating load. There are two processes involved in the face and bypass damper control function. The first is the process of modulating the dampers to maintain the Effective Discharge Heating Set Point. The second is the process of adjusting the Effective Discharge Heating Set Point up and down between the Minimum Discharge Heating Set Point and the Maxi-mum Discharge Heating Set Point as the Ctrl Temp= value varies above and below the Effective Heating Enable Set Point. The following sections describe these two processes.

Face and Bypass Damper Modulation. When the Disch Air= value falls below the Effective Discharge Heat-ing Set Point by more than half the Discharge Heating Dead Band, the face and bypass damper position is increased to the face. When the Disch Air= value rises above the Effec-tive Discharge Heating Set Point by more than half the Dis-charge Heating Dead Band, the face and bypass damper position is decreased to the face. The controller uses three PID control loop parameters to modulate the face and bypass dampers as the discharge air temperature changes - the Heating Proportional Band, Heat-ing Integral Time and Heating Period. Although these parameters can be adjusted, the factory default values for these parameters provide the best control for most applica-tions. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 107.



The controller uses three PID control loop parameters to raise and lower the Effective Discharge Heating Set Point as the Ctrl Temp= value changes. These are the Zone Heating Proportional Band, Zone Heating Integral Time and Zone Control Period. Although these parameters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 107. Steam or Hot Water Heat: Face and Bypass Damper Control-Modulating Valve MethodWhen a unit is equipped with steam or hot water with face and bypass damper heating there are two different methods available for controlling the heating arrangement. These are the “Open Valve” and “Modulating Valve” methods. This section describes the “Modulating Valve” method.When the Face and Bypass Method Flag is set to “Mod Valve”, control of the steam or hot water valve and the face and bypass dampers changes depending on the OA Temp= value.If the OA Temp= value is below the Face and Bypass Changeover Temperature setting, the steam or hot water valve is driven fully open when the unit enters the Heating operating state. The face and bypass dampers are then modu-lated to satisfy the heating load as described in the “Steam or Hot Water Heat: Face and Bypass Damper Control-Open Valve Method“ section above. If the OA Temp= value is above the Face and Bypass Changeover Temperature setting, the face and bypass damp-ers are driven fully open to the face when the unit enters the Heating operating state. The hot water or steam valve is then modulated to satisfy the heating load as described in the “Steam or Hot Water: Valve Control“ section above.Gas HeatWhen the unit enters the Heating operating state, the control-ler first holds the gas valve and the minimum fire position (either 5% or 33% depending on the burner model installed) until the Heating Interstage Timer expires. When the Heating Interstage Timer expires, the controller modulates the gas valve to satisfy the heating load. There are two processes involved in the heating valve control function. The first is the process of modulating the gas valve to maintain the Effective Discharge Heating Set Point. The second is the process of adjusting the Effective Discharge Heating Set Point up and down between the Minimum Discharge Heat-ing Set Point and the Maximum Discharge Heating Set Point as the Ctrl Temp= value varies above and below the Effec-tive Heating Enable Set Point. The following sections describe these two processes.

86 McQuay OM 138-3

Gas Valve Modulation. When the Disch Air= value falls below the Effective Discharge Heating Set Point by more than half the Discharge Heating Dead Band, the gas valve position is increased. When the Disch Air= value rises above the Effective Discharge Heating Set Point by more than half the Discharge Heating Dead Band, the gas valve position is decreased. The controller uses three PID control loop parameters to modulate the gas valve as the discharge air temperature changes. These are the Heating Proportional Band, Heating Integral Time and Heating Period. Although these parame-ters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 107.



The controller uses three PID control loop parameters to raise and lower the Effective Discharge Heating Set Point as the Ctrl Temp= value changes. These are the Zone Heating Proportional Band, Zone Heating Integral Time and Zone Control Period. Although these parameters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 107.

Effective Discharge Heating Set Point Limiting. On units equipped with modulating gas heat, the Effective Dis-charge Heating Set Point is limited according to a maximum heat exchanger temperature rise limit. This factory set limit varies depending on the unit burner model and can be found on the gas heat data plate attached to the unit. The controller does not allow the Effective Discharge Heating Set Point to be set above the current temperature entering the discharge fan, as indicated by the Ent Fan= parameter in the Tempera-tures menu, by more than this maximum heat exchanger temperature rise limit.

100% OA Units-Special Startup Sequence. If a unit is equipped with a 100% OA hood and high-turndown (5%) modulating gas heat, and heat is required at unit startup, the furnace enters a special burner startup sequence when the unit enters the Startup operating state. Pre-firing the burner allows the gas heat pre-purge sequence to occur and the burner to fire and warm up so that tempered air is available immediately when the fans start. The special sequence occurs if the Heat Status= parameter in the System or Zone Heating menu indicates “Htg Ena” and either of the follow-ing conditions are true:1. The Ctrl Temp= value is below Effective Heating

Enable Set Point by more than half the Heating Enable Dead Band.

2. The Min DAT Control Flag is set to “Yes” and the out-door air temperature is below the Minimum Discharge Temperature Limit by more than half the Discharge Heating Dead Band.

When the special gas heat startup sequence is activated upon entering the Startup operating state, the burner 90 pre-purge cycle is started at the same time as a four-minute timer. The burner starts and operates at the minimum fire position (5%) during this four-minute time period after the completion of the pre-purge cycle. When the four-minute timer expires, the

burner variable orifice is modulated to a “preheat firing rate” according to the formula below, where:Preheat Firing Time: The time increment that the variable orifice “increase” output relay (MCB-BO10) is energized to achieve the “preheat firing rate.” Thirty seconds is the maxi-mum.Variable Orifice Travel Time: The amount of time it takes the burner variable orifice to drive from the fully closed to fully open position (30 seconds-fixed).Applicable Discharge Air Temperature Set Point: Either the Effective Discharge Heating Set Point or the Minimum Discharge Temperature Limit. It is the Effective Discharge Heating Set Point if the Ctrl Temp= value is below Effective Heating Enable Set Point by more than half the Heating Enable Dead Band. It is the Minimum Discharge Tempera-ture Limit if the Ctrl Temp= value is above the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band, the Min DAT Control Flag is set to “Yes” and the outdoor air temperature is below the Minimum Dis-charge Temperature Limit by more than half the Discharge Heating Dead Band. Refer to “Discharge Air Low Limit Control” on page 89.

Preheat Firing Time Variable Orifice Travel Time Applicable Discharge Air Temperature Set Point Outdoor Air Temperature–Maximum Heat Exchanger Temperature Rise

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------×=

McQuay OM 138-3 87

Maximum Heat Exchanger Temperature Rise: The maxi-mum temperature rise across the heat exchanger for safe operation. This number varies with burner model and the baffle position and is programmed into the controller at the factory. This value can be found on the gas heat data plate attached to the unit. Refer also to “Software Identification and Configuration” on page 110.Outdoor Air Temperature: The current outdoor air temper-ature input to the controller.Once modulated to the “preheat firing rate”, the burner remains at this rate for a fixed thirty second time period to allow the heat exchanger to warm-up before the unit leaves the Startup and enters the Heating operating state at which time the fans are started. After entering the Heating operat-ing state, the burner remains at the “preheat firing rate” for a fixed four minute time period to allow the temperature to sta-bilize at this rate before “normal” gas heat control begins. When the unit enters the Heating operating state and “nor-mal” gas heat control begins, the controller then modulates the gas valve to maintain the Ctrl Temp= value at Effective Heating Enable Set Point as described above.Heating to Fan Only Operating StateThe unit will transition from the Heating to Fan Only operat-ing state when the Ctrl Temp= value is above the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band and the heating capacity has been at 0% for longer than the Heating Interstage Timer period. The unit will be at 0% capacity after the heating value reaches and has been at the low fire position (either 5% or 33% depending on the burner model installed) for longer than the Heating Inter-stage Timer period.

Note: The unit will also transition from the Heating to Fan Only operating state if Heating is disabled for any reason. Refer to “Htg Status” on page 46.

Morning Warm-up Control

On return air units, morning warm up operation occurs after the transition from unoccupied to occupied mode when the

Ctrl Temp= value is below the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band. Under these conditions, the controller enters the MWU oper-ating state after the normal startup sequence.


The MWU operating state is similar to the Heating operating state; the only difference is that the Eff Min OA Pos= param-eter is set to 0% during MWU. The unit remains in the MWU operating state until either the Ctrl Temp= value is equal to or greater than the Effective Heating Enable Set Point or the duration of the MWU operating state exceeds the Maximum Morning Warm-up Timer setting. In either case, since the Ctrl Temp= value has not risen above the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band when this occurs, the controller enters the Heating operating state.The Maximum Morning Warm-up Timer parameter is pro-vided to ensure that the required minimum ventilation air is being supplied after a known time regardless of the space temperature condition. For example, if actual occupancy is at 8:00 a.m. and unit startup is scheduled for 6:30 a.m., a Maxi-mum Morning Warm-up Timer setting of 90 minutes would ensure that the outdoor air dampers open to minimum posi-tion when building occupancy begins.

Note: The morning warm-up function does not occur on units equipped with 100% OA hoods.

High Ambient Heating Lockout

Heating is disabled whenever the outdoor air temperature is greater than the High Ambient Heating Lockout Set Point. When this occurs, the Htg Status= parameter in the System and Zone Heating menu indicates “Off Amb” if heating is not disabled for some other reason. When the outdoor air temperature drops below the High Ambient Heating Lockout Set Point by more than the High Ambient Heating Lockout Differential, heating operation is re-enabled.



Menu Name Item Name

Zone Heating




Timer Settings Max MWU= 90 min Maximum Morning Warm-up Timer



Menu Name Item Name

Zone HeatingOATHtg Lock= 55.0 ºF High Ambient Heating

Lockout Set Point

OATLock Diff= 1.0°F High Ambient Heating Lockout Differential

88 McQuay OM 138-3

Discharge Air Low Limit Control

If heating is enabled and there is no heating load (normally Fan Only operating state), the controller can activate the unit heating equipment as required to prevent the discharge air temperature from becoming too cool. It accomplishes this by entering the Min DAT operating state when necessary.Entering Min DAT Operating StateWhen the Min DAT Control Flag is set to “Yes” and if the Disch Temp= parameter falls below the Minimum Discharge Temperature Limit by more than half the Discharge Heating Dead Band, the unit operating state changes from Fan Only to Min DAT. When in the Min DAT operating state, heating capacity is increased if the Disch Temp= parameter is below the Minimum Discharge Temperature Limit by more than half the Discharge Heating Dead Band. Heating capacity is decreased if the Disch Temp= parameter rises above the Minimum Discharge Temperature Limit by more than half the Discharge Heating Dead Band. Leaving Min DAT Operating StateWhen the heating capacity has be 0% for one Heat Interstage Time period and the Disch Temp= parameter is above the Minimum Discharge Temperature Limit by more than half the Discharge Heating Dead Band, the unit leaves the Min DAT operating state and re-enters the Fan Only operating state.

Dehumidification

When the dehumidification function is active, the unit cooling coil is controlled to cool the air low enough to wring out mois-ture. Reheat is then supplied as necessary to provide properly conditioned air to the space. This is the only case in which the unit cooling and heating can be active simultaneously.

Enabling DehumidificationThe dehumidification function should only be enabled when the unit heating coil is located in a position down stream of the unit cooling coil. Also, before the dehumidification func-tion can be utilized, an optional humidity sensor must be field installed and wired to the unit or a humidity value must be provided via a network interface. For details regarding humidity sensor installation, refer to IM696, MicroTech II Applied Rooftop Unit Controller.



Menu Name Item Name

Discharge CoolingEff Clg Spt= 55.0 ºF Effective Discharge

Cooling Set Point


Discharge Heating Min DAT Ctrl= Yes Min DAT Control Flag



Menu Name Item Name

Dehumidification

Dehum Method= None Dehumidification Method Flag

RH Setpoint= 50% Relative Humidity Set Point

DewPoint Spt= 50 ºF Dew Point Set Point

RH Db= 2% Relative Humidity Dead Band

DewPnt Db= 2 ºF Dew Point Dead Band

Dehum Setup

Dehum Ctrl= OccupiedOccupied/Unoccu-pied Dehumidifica-

tion Flag

Minimum Stages= 2 Minimum Dehumidifi-cation Cooling Stages

Maximum Stages= 4 Maximum Dehumidifi-cation Stages

DH Stage Timer= 10 min

Dehumidification Interstage Timer

Sensor Loc= Return Humidity Sensor Location Flag

Reheat= Unit RH Only Reheat Type Flag

Zone Cooling Occ Clg Spt= 75.0ºF Cooling Enable Set Point

Zone HeatingEff Htg Spt= ____ ºF Effective Heating

Enable Set Point

Occ Htg Spt= 70.0ºF Heating Enable Set Point

McQuay OM 138-3 89

The dehumidification function is enabled by setting the Dehumidification Method Flag to either “RH” or “DewPnt”. When this parameter is set to “RH”, dehumidification opera-tion is controlled to maintain the Rel Humidity= value at the Relative Humidity Set Point. When this parameter is set to “DewPnt”, dehumidification operation is controlled to main-tain the Dew Point= value at the Dew Point Set Point.

Note: The Dew Point= value is calculated by the control-ler using the Rel Humidity= value and either the Space Temp= or Return Air= value, depending on the setting of the Humidity Sensor Location Flag. This parameter can either be set to “Space” or “Return.”

When the Dehumidification Method Flag is set to “None”, the dehumidification function is disabled.The dehumidification function is also disabled if mechanical cooling is disabled for any reason or if heating is disabled for any reason other than due to outdoor air temperature lockout.Occupied/Unoccupied DehumidificationWhen the Occupied/Unoccupied Dehumidification Flag is set to “Occupied” then the dehumidification function will be enabled during occupied and disabled during unoccupied unit operation. If unoccupied dehumidification operation is required, the Occupied/Unoccupied Dehumidification Flag must be set to “Always”. In this case the dehumidification function is enabled both during occupied and unoccupied operation. During unoccupied periods the unit will start up an operate the dehumidification function until the relative humidity (or dew point) set point is satisfied and then shut back off.

Dehumidification Cooling OperationWhen the dehumidification function is enabled and the Rel Humidity= (or Dew Point=) value rises above the Relative Humidity Set Point (or Dew Point Set Point) by more than half the Relative Humidity Dead Band (or Dew Point Dead Band), the dehumidification function is turned on. When the dehumidification function is turned on, the unit enters the Fan On, Min DAT or Heating operating state. When the dehumidification function is turned on, the unit is prevented from entering the Econo or Cooling operating state. The cooling equipment functions as described in the following sections.Compressorized CoolingWhen the dehumidification function is turned on, the cooling is staged up rapidly to the Minimum Dehumidification Stages and the Dehumidification Interstage Timer begins timing down.When the Dehumidification Interstage Timer expires, if the Rel Humidity= (or Dew Point=) value is still above the Rel-ative Humidity Set Point (or Dew Point Set Point) by more than half the Relative Humidity Dead Band (or Dew Point Dead Band) cooling is staged up rapidly to the Maximum

Dehumidification Stages. The Dehumidification Interstage Timer again is reset and begins timing down.If at the Maximum Dehumidification Stages and the Rel Humidity= (or Dew Point=) value is below the Relative Humidity Set Point (or Dew Point Set Point) by more than half the Relative Humidity Dead Band (or Dew Point Dead Band) when the Dehumidification Interstage Timer expires, cooling is staged down rapidly to the Minimum Dehumidifi-cation Stages. The Dehumidification Interstage Timer again is reset and begins timing down. If at the Minimum Dehumidification Stages and the Rel Humidity= (or Dew Point=) value is below the Relative Humidity Set Point (or Dew Point Set Point) by more than half the Relative Humidity Dead Band (or Dew Point Dead Band) when the Dehumidification Interstage Timer expires, cooling is staged off rapidly and the dehumidification func-tion is turned off.Chilled Water CoolingWhen the dehumidification function is turned on, the chilled water valve is driven to 100% capacity and the Relative Humidity Interstage Timer begins timing down.If the Rel Humidity= (or Dew Point=) value is below the Relative Humidity Set Point (or Dew Point Set Point) by more than half the Relative Humidity Dead Band when the Dehumidification Interstage Timer expires, the chilled water valve is driven closed and the dehumidification function is turned off.

Dehumidification Heating OperationWhen the dehumidification function is turned on, the unit enters the Heating operating state and then is allow to transi-tion between the Heating, Min DAT and Fan Only operating states as required to maintain the zone temperature condi-tions. The unit is prevented from entering the Econo or Cool-ing operating states.The only difference between dehumidification heating and normal heating operation is that the Effective Heating Enable Set Point is set equal to the current Space Temp= value when the dehumidification function is turned on. The Effective Heating Enable Set Point then remains at this value while the dehumidification function is on. When the dehu-midification function is turned off, the Effective Heating Enable Set Point returns to its normal value.

Note: The value the Effective Heating Enable Set Point is set to when the dehumidification function is turned on is limited between the Cooling Enable Set Point and the Heating Enable Set Point.

Unit Reheat OnlyWhen the Reheat Type Flag is set to “Unit RH Only” and the dehumidification function is active, reheat is only provided by the standard unit heat. The unit transitions between the Fan Only, Min DAT, and Heating operating states in the nor-mal manner.

90 McQuay OM 138-3

Unit &Auxiliary ReheatWhen the Reheat Type Flag is set to "Unit&Aux RH" and the dehumidification function is active reheat is provided by a combination of a pair of auxiliary reheat outputs (MCB-B013 and MCB-B014) on the main control board and the standard unit heat. The auxiliary reheat outputs can be used, for example, to energize hot gas reheat valves when the cool-ing circuits are active during dehumidification operation.When dehumidification is active with both cooling circuits running the auxiliary reheat outputs are cycled on and off together (subject to the heating inter-stage timer) to maintain the Control Temperature at the Effective Heating Enable Set-point. If the auxiliary reheat outputs have been on for longer than the heating inter-stage timer and reheat is still required, the unit will transition between the Min DAT and Heating operating states using the standard unit heat in the normal manner. Once the reheat requirements are satisfied the unit will transition out of the Heating or Min DAT operating states to the Fan Only operating state, shutting off the stan-dard unit heat. Once in the Fan Only operating state, the aux-iliary reheat outputs will shut off if the Control Temperature is above the Effective Heating Enable Setpoint. Aux Reheat OnlyWhen the Reheat Type Flag is set to "Aux RH Only" and the dehumidification function is active reheat is provided only by a pair of auxiliary reheat outputs (MCB-B013 and MCB-B014) on the main control board. Any standard unit heat is disabled during dehumidification operation. The auxiliary reheat outputs can be used, for example, to energize hot gas reheat valves when the cooling circuits are active during dehumidification operation.When dehumidification is active with both cooling circuits running the auxiliary reheat outputs are cycled on and off together (subject to the heating inter-stage timer) to maintain the Control Temperature at the Effective Heating Enable Set-point.

Energy Recovery When a unit is equipped with an optional energy recovery wheel, energy recovery is provided by drawing outside air across half of an enthalpy wheel and drawing exhaust air across the other half. Latent and sensible heat is transferred from the hotter moist exhaust air to the colder dry outside air in winter. Latent and sensible heat is transferred from the hotter moist outside air to the cooler dry exhaust air in sum-mer. Energy recovery control consists of starting and stop-ping an exhaust fan, modulating the speed of the exhaust fan, starting and stopping an enthalpy wheel, optionally control-ling the speed of the enthalpy wheel and opening and closing a set of bypass dampers. The outdoor dampers are controlled in the normal manner. Refer to “100% Outdoor Air Damper Control” on page 70 or “Economizer” on page 70 as applica-ble. The following sections describe the control of the enthalpy wheel, exhaust fan and bypass dampers.

Enthalpy Wheel Control

Units with EconomizerWhen the Energy Recovery Control Flag is set to “Yes”, the enthalpy wheel is turned on whenever the unit exhaust fan is on and the current OA Damper Pos= parameter in the OA Damper menu indicates a value within 3% of the Effective Minimum Outdoor Damper Position Set Point. It is turned off when the exhaust fan is turned off or the OA Damper Pos= value is greater than the Effective Minimum Outdoor Damper Position Set Point by more than 3°F (as when the unit is in the Econo operating state.

Note: The wheel can also be turned off if the unit is equipped with the energy wheel frost protection option and the wheel is exposed to frosting condi-tions. Refer to the “Variable Speed Enthalpy Wheel” on page 91 below.

100% OA UnitsWhen the Energy Recovery Control Flag is set to “Yes,” the enthalpy wheel is turned on whenever the unit exhaust fan is turned on. It is turned off whenever the exhaust fan is turned off.

Note: The wheel can also be turned Off if the unit is equipped with the energy wheel frost protection option and the wheel is exposed to frosting condi-tions. Refer to the “Variable Speed Enthalpy Wheel” on page 91 below.

Constant Speed Enthalpy WheelWhen the unit is equipped with a constant speed enthalpy wheel, the wheel is driven to maximum speed whenever the enthalpy wheel is on.Variable Speed Enthalpy WheelWhen the unit is equipped with the energy recovery wheel frost protection option, it has a variable speed enthalpy wheel. The wheel is driven to maximum speed whenever the enthalpy wheel is on. The speed of the wheel may be modu-lated as described below to prevent wheel frosting.



Menu Name Item Name

OA Damper Eff Min OA Pos= ___%Effective Minimum Outdoor Damper Position Set Point

Energy Recovery Energy Rec= No Energy Recovery

Control Flag

Energy Rec Setup

Min Exh T Diff= 2°F Energy Recovery Wheel Proportional Band

Max Exh T Diff= 6°F Energy Recovery Wheel Integral Time

Stage Time= 5 min Heat Recovery Wheel Period

Min Off Time= 20min Enthalpy Wheel Minimum Off Time

McQuay OM 138-3 91

When there is a threat of frost on the enthalpy wheel, the wheel is slowed down or stopped so that less enthalpy trans-fer occurs and frosting of the wheel is avoided. Frosting can occur on the enthalpy wheel when the exhaust air leaving the wheel is saturated. This condition occurs when two lines intersect on a psychrometric chart, and it does not occur when these two lines do not intersect. One of these lines is the Humidity Ratio versus the dry bulb temperature for satu-rated air. The other line is the exhaust air process line. The exhaust air process line is defined by two points on a psycho-metric chart. The first point on this line is the outdoor air temperature at 95% relative humidity (point 1 in Figure 9) and the second point on the line is the return air temperature at the return air relative humidity (point 2 in Figure 9). One exhaust air process line showing frosting conditions and another showing no frost conditions is shown in Figure 9. The controller makes a continuous calculation to determine if and at what temperatures the saturated air and exhaust air lines intersect. When they do not intersect, the enthalpy wheel runs at full speed. When they do intersect, the enthalpy wheel is controlled to a slower speed to maintain the dry bulb temperature of the exhaust air leaving the enthalpy wheel above the higher of the two intersecting dry bulb temperatures (point ST2 in Figure 9). This is referred to as the “Intersection Point”. This prevents the wheel from operating under frosting conditions.The following describes the details involved in the frost pro-tection function that affect the speed and start/stop of the enthalpy wheel.When the enthalpy wheel has been operating at maximum speed for at least the Enthalpy Wheel Stage Time and the exhaust air temperature leaving the wheel (ER ExhT=) drops below the Intersection Point plus the Minimum Temperature Difference, the enthalpy wheel will be slowed to its mini-mum speed.

If the enthalpy wheel has been operating at minimum speed for at least the Enthalpy Wheel Stage Time and the exhaust air temperature leaving the wheel (ER ExhT=) is still below the Intersection Point plus the Minimum Temperature Dif-ference, the enthalpy wheel will be stopped.If the exhaust air temperature leaving the wheel (ER ExhT=) then rises above the Intersection Point plus the Maximum Temperature Difference and the enthalpy wheel has been off for longer than the Enthalpy Wheel Minimum Off Time, the wheel will be restarted and will run at its minimum speed.If the enthalpy wheel has been at minimum speed for longer than the Enthalpy Wheel Stage Time and the exhaust air tem-perature leaving the wheel (ER ExhT=) is still above the Intersection Point plus the Maximum Temperature Differ-ence the wheel will be increased to its maximum speed.

Figure 9:Variable Speed Enthalpy Wheel Frost Protection - Psychrometric Chart

Saturated Air

Enthalpy WheelExhaust Air (FrostConditions)

Enthalpy WheelExhaust Air (NoFrost Conditions)

Saturated Air

ST1

1

ST2

2

2SaturationTemperature

Hum

idity

Rat

io

Dry Bulb Temperature

(Intersection Point)

92 McQuay OM 138-3

Exhaust Fan Control

Building Pressure ControlWhen the unit is equipped with a 0-100% modulating econo-mizer or is 100% OA with a variable capacity discharge fan, the energy recovery option includes a variable capacity exhaust fan equipped with either a VFD or variable inlet vanes. When the Energy Recovery Control Flag is set to “Yes”, the Return/Exhaust Fan Capacity Control Flag is set to “BldgPres” and the Second Pressure Sensor Present Flag is set to “Bldg”, the exhaust fan is controlled based on the building static pressure. The exhaust fan is turned on when the discharge fan is running and the Bldg Press= parameter value is above the Building Static Pressure Set Point high by more than half the Building Static Pressure Dead Band for longer than the Minimum Exhaust Fan Off Timer.

Note: If the unit is 100% OA with a constant volume dis-charge fan, the exhaust fan is turned on whenever the outdoor air dampers are open.

The exhaust fan remains on until either of the following occur:1. The Bldg Press= parameter value drops below the

Building Static Pressure Set Point by more than half the Building Static Pressure Deadband and the RF/EF Fan Cap= value has been at the Exhaust Fan Minimum Capacity Value for longer than the Minimum Exhaust Fan On Timer.

2. The discharge fan is turned off.When the exhaust fan is on, its capacity is modulated to maintain the Bldg Press= parameter value at the Building Static Pressure Set Point using three PID control loop param-eters. These are the Building Static Pressure Proportional Band, Building Static Pressure Integral Time and Building Static Pressure Period. Although these parameters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed infor-mation regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 107.Direct Position ControlWhen the unit is equipped with a 0-100% modulating econo-mizer or is 100% OA with a variable capacity discharge fan, the energy recovery option includes a variable capacity exhaust fan equipped with either a VFD or variable inlet vanes. When the Energy Recovery Control Flag is set to “Yes” and the Return/Exhaust Fan Capacity Control Flag is set to “Position”, the exhaust fan is controlled based on Remote Return/Exhaust Fan Capacity Set Point. This set point can be adjusted via network signal. The exhaust fan is turned on when the discharge fan is running and the exhaust fan capacity is commanded above the Exhaust Fan Minimum Capacity Value for longer than the Minimum Exhaust Fan Off Timer.

Note: If the unit is 100% OA with a constant volume dis-charge fan, the exhaust fan is turned on whenever the outdoor air dampers are open.

The exhaust fan remains on until either of the following occur:1. The Remote Return/Exhaust Fan Capacity Set Point is

commanded to the Exhaust Fan Minimum Capacity Value for longer than the Minimum Exhaust Fan On Timer.

2. The discharge fan is turned off.



Menu Name Item Name

Bldg PressureBldgSP Spt= 1.00 “WC Building Static Pres-

sure Set Point

BSP Db= 0.080 “WC Building Static Pres-sure Dead Band

OA Damper Eff Min OA Pos = __ %Effective Minimum Outdoor Damper Position Set Point

Building Static P Setup

BSP Propbd= 0.400 “WCBuilding Static Pres-

sure Proportional Band

BSP IntTime= 2.0 sec Building Static Pres-sure Integral Time

BSP Period= 2.0 sec Building Static Pres-sure Period

Energy RecoveryEF Min Cap= 5% Exhaust Fan Mini-

mum Capacity Value

Energy Rec= No Energy Recovery Control Flag

Energy Rec SetupMin Exh On= 120 sec Minimum Exhaust

Fan On Timer

Min Exh Off= 120 sec Minimum Exhaust Fan Off Timer

Unit Configuration


RF/EF Ctrl= Tracking Return/Exhaust Fan Capacity Control Flag

Rem RF/EF Cap= 25%Remote

Return/Exhaust Fan Capacity Set Point

McQuay OM 138-3 93

Energy Recovery Bypass Damper Control

When a unit is equipped with a 0-100% modulating econo-mizer, the energy recovery option includes a set of bypass dampers that allow air to bypass the energy recovery wheel when the wheel is not operating. The dampers are driven closed for 2 minutes whenever the energy recovery wheel is turned on, forcing the entering and leaving air to go through the wheel. When the outdoor air dampers are driven more than 3% above the effective Minimum Outdoor Damper Position Set Point (as when the unit enters the Economizer operating state the wheel is shut off and the bypass dampers are driven open for 2 minutes allowing the entering and leav-ing air to bypass the wheel.

Return Fan Capacity ControlWhen a unit is equipped with return fan inlet guide vanes or a return fan VFD, there are two optional methods for con-trolling the return fan capacity. These are “direct building static pressure” control and “position” control. The follow-ing sections describe the two methods.

Direct Building Static Pressure Control

When the Return/Exhaust Fan Capacity Control Flag is set to “BldgPres” and the Second Pressure Sensor Present Flag is

set to “Bldg”, the controller modulates the return fan capac-ity to maintain the Bldg Static Pressure Set Point.

Note: Note that this feature requires an optional building static pressure sensor.

To do this, it uses three PID control loop parameters to mod-ulate the return capacity as the building static pressure changes. Theses are Building Static Pressure Proportional Band, Building Static Pressure Integral Time and Building Static Pressure Period. Although these parameters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed infor-mation regarding tuning PID control loop parameters; refer to “MicroTech II DDC Features” on page 107.Building static pressure control of the return air fan airflow is overridden under two conditions. 1. The first condition is when the return fan capacity mod-

ulates down to 17% or the VFD speed is reduced to 25%. The controller does not allow the return fan capac-ity to modulate below these fixed values.

2. The second condition is when the outdoor air dampers are completely closed. In this case the return fan capac-ity tracks the discharge fan capacity one-to-one. In the case of a constant volume discharge fan the return fan airflow is driven to 100%.

Return Fan Direct Position Control

When the Return/Exhaust Fan Capacity Control Flag is set to “Position”, the controller positions the return or exhaust fan inlet vanes or VFD speed to the Remote Return/Exhaust Fan Capacity Set Point. Normal building static pressure control is overridden in this case. The Remote Return/Exhaust Fan Capacity Set Point is then set via a network signal. If net-work communications is interrupted or is not present, the Remote Return/Exhaust Fan Capacity Set Point remains at the last commanded setting and then can be adjusted via the unit keypad/display. The Remote Return/Exhaust Fan Capacity Set Point can be adjusted from the fixed minimum (17% for vanes or 25% for VFD applications) to 100%. When the Return/Exhaust Fan Capacity Control Flag is set to “BldgPres”, the Remote Return/Exhaust Fan Capacity Set Point has no effect on the unit operation.



Menu Name Item Name

OA Damper Eff MinOA Pos= ___%Effective Minimum

Outdoor Damper Posi-tion Set Point



Menu Name Item Name

Bldg PressureBldgSP Spt= 0.050 “WC Building Static Pres-

sure Set Point

BSP Db= 0.010 “WC Building Static Pres-sure Dead Band


BSP Propbd= 1.0 “WCBuilding Static Pres-

sure Proportional Band

BSP IntTime= 10 sec Building Static Pres-sure Integral Time

BSP Period= 5 sec Building Static Pres-sure Period

Unit Configuration2nd P Sensor= Bldg Second Pressure

Sensor Present Flag

RF/EFCtrl= BldgPres Return/Exhaust Fan Capacity Control Flag



Menu Name Item Name

Unit Configuration

RF/EF Ctrl= BldgPresReturn/Exhaust Fan

Capacity Control Flag

Rem RF/EF Cap= 25%

Remote Return/Exhaust Fan Capacity Set Point

94 McQuay OM 138-3

SAF/RAF Differential OA ResetWhen a unit is equipped with return air fan inlets vanes or VFD it may be necessary to increase the amount of outdoor air if the difference between the discharge and return fan capacity gets to large. If this is not done the discharge air fan can potentially become “starved” for air. A discharge fan operating in a “starved” condition not only has difficulty meeting the system airflow requirements but may cause excessive vibration and/or damage to damper sets and/or return fan motors or VFD. To overcome this type of prob-lem, the MicroTech II unit controller provides a dis-charge/return fan differential OA reset strategy, which automatically resets outdoor air dampers as the difference between the discharge and return air fan capacity varies. Refer to “Discharge/Return Fan Differential OA Reset” on page 74.

Note: On a zone (or space comfort) control unit, the dis-charge fan capacity is always assumed to be 100%.

Propeller Exhaust Fan ControlWhen a unit is equipped with the propeller exhaust fan option, it is equipped with a VFD to control the speed of the propeller fan(s). There are two different methods for control-ling the exhaust fan capacity. These are “direct building static pressure” control and “position” control. The follow-ing sections describe the two methods.

Direct Building Static Pressure Control

When a unit is equipped with the propeller exhaust fan option and, therefore, is equipped with a VFD for controlling

the speed of the propeller fan(s), the VFD can be controlled based on building static pressure.

Note: This control option requires an optional building static pressure sensor, the Return/Exhaust Fan Capacity Control Flag is set to “BldgPres” and the Second Pressure Sensor Present Flag is set to “Bldg”.

Exhaust Fan Start/Stop Control The exhaust fans are started when all of the following condi-tions are met for longer than the Minimum Start Time setting:1. The current OA Damper= value is above the Minimum

Outdoor Air Damper Position setting.2. The current Disch Fan Cap= value is above the Mini-

mum Discharge Fan Capacity setting (or the unit has a constant volume discharge fan).

3. The current Bldg Press= value is above the Building Static Pressure Set Point by more than half the Building Static Pressure Dead Band.

The exhaust fans are stopped when the current Bldg Press= value is below the Building Static Pressure Set Point by more than half the Building Static Pressure Dead Band and the current RF/EF Fan Cap= value has been at or below the Minimum Exhaust Fan Capacity for longer than the Mini-mum Stop Time.Exhaust Fan VFD Speed ControlWhen the exhaust fans are on, the speed of the exhaust fan VFD is controlled to maintain the current Bldg Pres= value at the Building Static Pressure Set Point. To do this the con-troller uses three PID control loop parameters to modulate the exhaust fan capacity as the building pressure changes. These are the Building Static Pressure Proportional Band, Building Static Pressure Integral Time and Building Static Pressure Period. Although these parameters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 117.



Menu Name Menu Item

Bldg PressureBldgSP Spt= 0.050 “WC Building Static Pressure

Set Point

BSP Db= 0.010 “WC Building Static Pressure Dead Band


BSP Propbd= 1.0 “WC Building Static Pressure Proportional Band

BSP IntTime= 10 Sec Building Static Pressure Integral Time

BSP Period= 5 Sec Building Static Pressure Period

Exhaust Fan Setup

Min Exh Fan Cap= 25% Minimum Exhaust Fan Capacity

Min OA Dmpr Pos= 5% Minimum Outdoor Air Damper Position

Min DF Cap= 10% Minimum Discharge Fan Capacity

Min Strt Time= 120 Sec Minimum Start Time

Min Stop Time= 120 Sec Minimum Stop Time

Unit Configuration



McQuay OM 138-3 95

Exhaust Fan Direct Position Control

When a unit is equipped with the propeller exhaust fan option and, therefore, is equipped with a VFD for controlling the speed of the propeller fan(s), the VFD can be controlled to a specific position set point based on a network signal.

Note: This control option requires that the Return/Exhaust Fan Capacity Control Flag is set to “Position”.

Exhaust Fan Start/Stop Control The exhaust fans are started when all of the following condi-tions are met for longer than the Minimum Start Time setting:1. The current OA Damper= value is above the Minimum

Outdoor Air Damper Position setting.2. The current Disch Fan Cap= value is above the Mini-

mum Discharge Fan Capacity setting (or the unit has a constant volume discharge fan).

3. The Remote Return/Exhaust Fan Capacity Set Point is set to a value above the Minimum Exhaust Fan Capacity setting.

The exhaust fans are stopped when the Remote Return/Exhaust Fan Capacity Set Point is set equal to the Minimum Exhaust Fan Capacity setting for longer than the Minimum Stop Time.Exhaust Fan VFD Speed ControlWhen the exhaust fans are on and the Return/Exhaust Fan Capacity Control Flag is set to “Position”, the speed of the exhaust fan VFD is controlled to the Remote Return/Exhaust Fan Capacity Set Point. Normal building static pressure con-trol is overridden in this case. If network communications is interrupted or is not present, the Remote Return/Exhaust Fan Capacity Set Point remains at the last commanded setting and then can be adjusted via the unit keypad/display. The Remote Return/Exhaust Fan Capacity Set Point can be adjusted from 0% to 100%.

Unoccupied ControlUnoccupied Heating (Night Setback)

If an optional space (or zone) temperature sensor (ZNT1) is connected to the controller, the Space Sensor Present Flag is set to “Yes” and the Unoccupied Heating Set Point is set higher than 0°F, unoccupied heating (night setback) opera-tion is available. Unoccupied heating operation is disabled if either the Space Sensor Present Flag is set to “No” or the Unoccupied Heating Set Point is set to 0°F. The following is a description of unoccupied heating operation:If the space temperature falls to the Unoccupied Heating Set Point while the unit is in the Off Unoc operating state, the unit starts and runs.1 The controller enters the UnocHtg operating state after the normal startup sequence. Refer to “Startup Control” on page 66. The UnocHtg operating state is similar to the Heating operating state except that the out-door air dampers remain closed in the UnocHtg operating state. When the space temperature rises above the Unoccupied Heating Set Point by more than the Unoccupied Heating Dif-ferential, heating operation ends and the controller shuts down the fans and returns to the Off Unoc state.

Note: The Unoccupied Heating Set Point cannot be set higher than the Occ Htg Spt= parameter.

Emergency Space Sensor Failure OperationA unit starts and runs in an emergency mode of operation if all of the following are true:1. The Space Sensor Present Flag is set to “Yes”2. The Unoccupied Heating Set Point is set higher than 0°F3. The current value of the OA Temp= parameter is below

40°F.4. The Space Temp problem alarm occurs.5. Unit is equipped with a functioning return temperature

sensor.In this mode of operation the unit starts and runs continu-ously using the return air temperature sensor as the “Control Temperature.” Refer to “Control Temperature” on page 68.



Menu Name Menu Item

Exhaust Fan Setup

Min Exh Fan Cap= 25% Minimum Exhaust Fan Capacity

Min OA Dmpr Pos= 5% Minimum Outdoor Air Damper Position

Min DF Cap= 10% Minimum Discharge Fan Capacity

Min Strt Time= 120 Sec Minimum Start Time

Min Stop Time= 120 Sec Minimum Stop Time

Unit Configuration


Rem RF/EF Cap= 25% Remote Return/Exhaust Fan Capacity Set Point



Menu Name Item Name

Zone HeatingUnoccHtg Spt= 55.0 ºF Unoccupied Heat-

ing Set Point

UnoccHtgDiff= 3°F Unoccupied Heat-ing Differential


1. The unit does not activate unoccupied heating or cooling operation if the UnitStatus= parameter in the System menu indicates “Off Man”, “Off Sw”, “Off Net” or “Off Alm.”

96 McQuay OM 138-3

Unoccupied Cooling (Night Setup)

If an optional space (or zone) temperature sensor (ZNT1) is connected to the controller, the Space Sensor Present Flag is set to “Yes” and the Unoccupied Cooling Set Point is set lower than 99°F, unoccupied cooling (night setup) operation is available. Unoccupied cooling operation is disabled if either the Space Sensor Present Flag is set to “No” or the Unoccupied Cooling Set Point is set to 99°F. The following is a description of unoccupied cooling operation:If the space temperature rises to the Unoccupied Cooling Set Point while the unit is in the Off Unoc state, the unit starts and runs.1 If the unit has an economizer and the OA Ambi-ent= parameter indicates “Low”, the controller enters the UnocEcon operating state after the normal startup sequence. If OA Ambient= parameter indicates “High” or the outdoor air is not cool enough to maintain the Eff Clg Spt= setting in the Discharge Cooling menu (or the unit has no economizer), the controller enters the UnocClg operating state and acti-vates mechanical cooling after the normal startup sequence. The UnocEcon and UnocClg operating states are similar to the Econo and Cooling operating states except that the Eff MinOA Pos= parameter is set to 0%. If the OA Ambient= parameter indicates “Low”, the outdoor air dampers are wide open during UnocClg. If the OA Ambient= parameter indi-cates “High” (or there is no economizer), the outdoor air dampers are fully closed during UnocClg.When the space temperature drops below the Unoccupied Cooling Set Point by more than the Unoccupied Cooling Differential, cooling operation ends and the controller shuts down the fans and returns to the Off Unoc state.

Note: The Unoccupied Cooling Set Point cannot be set lower than the Occ Clg Spt= parameter.

Purge

If a unit is equipped with an economizer and an optional space (or zone) temperature sensor (ZNT1) is connected to the controller, pre-occupancy purge control is available. Designed to take advantage of cool pre-dawn outdoor air, purge control starts the fans and modulates the economizer dampers to maintain occupied cooling requirements during unoccupied periods. The purge function can only be used in conjunction with the unit internal time schedule.Purge operation is possible only during a time window prior to occupancy that is defined by the Maximum Purge Time parameter (0 to 240 minutes). For example, if the unit is scheduled to start at 6:30 a.m., a Maximum Purge Time of 60 minutes (default) allows purge operation to occur between 5:30 a.m. and 6:30 a.m.During the purge time window, the unit starts and runs when the following three requirements are all met:

• The Space Temp= value is greater than the Effective Cooling Enable Set Point by more than half the Cooling Enable Deadband.

• The OA Ambient= value in the OA Damper menu indi-cates “Low.”

• The OA Temp= value is below the Space Temp= value by more than 4°F.

During purge operation, the controller enters and remains in the UnocEcon operating state after the normal startup sequence. Mechanical cooling is disabled. Economizer con-trol during purge operation is similar to that during occupied operation.The unit returns to the Off Unoc state when any of the fol-lowing three conditions occur:

• The Space Temp= value is less than the Effective Cool-ing Enable Set Point by more than half the Cooling Enable Deadband.

• The OA Ambient= value in the OA Damper menu indi-cates “High.”

• The OA Temp= value rises above the Space Temp= value by more than 2°F.

As conditions allow, purge control cycles the unit in this manner until normal occupied operation begins. If the sched-uled occupied startup time occurs during purge operation, the unit continues running without interruption.



Menu Name Item Name

Zone CoolingUnoccClg Spt= 85.0 ºF Unoccupied Cool-

ing Set Point

UnoccClgDiff= 3°F Unoccupied Cool-ing Differential




Menu Name Item Name

Zone CoolingEff Clg Spt= 75.0 ºF Effective Cooling

Enable Set Point

Clg Deadband= 1.0 ºF Cooling Enable Dead-band

OA Damper Max Purge= 60 min Maximum Purge Time

McQuay OM 138-3 97

Special Space Sensor Failure Operation

When a unit is equipped with an optional space (or zone) temperature sensor (ZNT1) a special “space sensor failure” mode of operation is available if the unit is also equipped with a functioning return air temperature sensor. This special mode of operation is activated when all of the following conditions are met:1. The Space Sensor Present Flag is set to “Yes.”2. The Unoccupied Heating Set Point is set higher

than 0°F.3. The current OA Temp= value is below 40°F.4. The space temperature sensor fails while the unit is in

the Off Unoc operation state.In this mode, the unit starts up and runs as it normally would during an occupied period, controlling temperature using the return air sensor as the Control Temperature Source.

Alarm ControlThe following are descriptions of the various alarms that can occur in zone (or space comfort) control rooftop units.

Note: The cause of a manual reset alarm should be inves-tigated and eliminated before the unit or any dis-abled equipment in it is placed back into service.

FaultsFreezeWhen a unit is equipped with a chilled water, hot water, or steam coil, the Freeze fault occurs when the optional freez-estat (FS1) contacts open (binary input MCB-BI7 off) as a result of detecting an abnormally low water or steam coil temperature while the fans are running.When the Freeze fault occurs, the controller shuts down the fans, closes the outdoor air dampers, opens the chilled water and heating valves and sets a 10-minute timer.When the 10-minute timer expires, the controller checks the freezestat input again. If the freezestat contacts are closed (binary input MCB-BI7 on), the valves close. If the freez-estat contacts are still open (binary input MCB-BI7 off), the

valves remain open, and the 10-minute timer resets. This continues until the fault is manually cleared through the unit keypad or via a network signal.SmokeThe Smoke fault occurs when the contacts of either optional discharge or return air smoke detector (SD1 or SD2) open (binary input MCB-BI8 off).When the Smoke fault occurs, the unit is immediately shut down. The unit remains shut down until the smoke detector is manually reset and the Smoke fault is manually cleared through the unit keypad or via a network signal.

Note: The smoke detector can be reset by pressing the reset button on or by momentarily removing power from the device. This can be accomplished by cycling control power (S1 switch).

Space SensorIf the optional space temperature sensor (ZNT1) fails (ana-log input MCB-AI1 open or short-circuited) while it is acting as the “Control Temperature” (CtrlTemp Src= parameter is set to “Space”) and the unit has no return air sensor, the Space Sensor fault occurs.When the Space Sensor fault occurs, the unit is shut down. It remains shut down until the Space Sensor fault is manually cleared through the unit keypad or via a network signal.Return SensorIf the unit is equipped with a return air temperature sensor (RAT) and it fails (analog input MCB-AI4 open or short-cir-cuited) while it is acting as the “Control Temperature” (Ctr-lTemp Src= parameter is set to “Return”), the Return Sensor fault occurs.When the Return Sensor fault occurs, the unit is shut down. It remains shut down until the Return Sensor fault is manu-ally cleared through the unit keypad or via a network signal.Disch SensorIf the discharge air temperature sensor (DAT) fails (analog input MCB-AI3 open or short-circuited), the Disch Sensor fault occurs.When the Disch Sensor fault occurs, the unit is shut down. It remains shut down until the Disch Sensor fault is manually cleared through the unit keypad or via a network signal.Hi Return TmpIf the unit is equipped with a return air temperature sensor and the Return Air= parameter value exceeds the Hi Return Alm= value in the Alarm Limits menu, while the unit is operational, the Hi Return Tmp fault occurs.When the Hi Return Tmp fault occurs, the unit is shut down. It remains shut down until the Hi Return Tmp fault is manu-ally cleared through the unit keypad or via a network signal.



Menu Name Menu Item

Zone HeatingCntlTempSrc= Return Control Temperature

Source

UnoccHtg Spt= 55°F Unoccupied Heating Set Point

Unit Configuration Space Sensor= Yes Space Sensor Present

Flag

98 McQuay OM 138-3

Hi Disch TmpIf the Disch Air= parameter value exceeds the Hi Disch Alm= setting in the Alarm Limits menu, while the unit is operational, the Hi Disch Tmp fault occurs.When the Hi Disch Tmp fault occurs, the unit is shut down. It remains shut down until the Hi Disch Tmp fault is manu-ally cleared through the unit keypad or via a network signal.Lo Disch TmpIf the Disch Air= parameter value drops below the Lo Disch Alm= setting in the Alarm Limits menu for longer than 3 minutes while the unit is operational, the Lo Disch Tmp fault occurs.When the Lo Disch Tmp fault occurs, the unit is shut down. It remains shut down until the Lo Disch Tmp fault is manu-ally cleared through the unit keypad or via a network signal.

Note: The Lo Disch Tmp fault is ignored when the unit leaves the Startup operating state for a time period defined by the Low DAT= parameter in the Timer Settings menu and when the unit is in the Cooling operating state.

Note: The Lo Disch Tmp fault is disabled if the Lo Disch Alm= parameter is set to its minimum value of 20°F.

Fan FailIf differential pressure switch PC7 fails to detect airflow (binary input MCB-BI6 off) within two minutes after the unit leaves the Startup operating state or any time afterward, while the unit is running, the Fan Fail fault occurs.When the Fan Fail fault occurs, the unit is shut down. It remains shut down until the Fan Fail fault is manually cleared through the unit keypad or via a network signal.OA Dmpr StuckOn units equipped with a 100% outdoor air hood, the out-door air dampers are driven fully open during the Startup operating state before the discharge fan is started. If the OA Damper Pos= parameter in the OA Damper menu does not indicate 50% or greater when the unit leaves the Startup operating state, the OA Dmpr Stuck fault occurs.

When the OA Dmpr Stuck fault occurs, the unit is shut down. The unit remains shut down until the OA Dmpr Stuck fault is manually cleared through the unit keypad or via a network signal.

ProblemsFreezeWhen a unit is equipped with a chilled water, hot water, or steam coil, the Freeze problem occurs when the optional freezestat (FSl) contacts open (binary input MCB-BI7 off) as a result of detecting an abnormally low water or steam coil temperature while the fans are off.When the Freeze problem occurs, the controller opens the chilled water and heating valves and set a 10-minute timer.When the 10-minute timer expires, the controller checks the freezestat input again. If the freezestat contacts are closed (binary input MCB-BI7 on), the valves close. If the freez-estat contacts are still open (binary input MCB-BI7 off), the valves remain open, and the 10-minute timer resets. This continues while the unit remains off.Whenever the freezestat closes (binary input MCB-BI7 on), the Freeze problem automatically clears. This feature pro-tects the coil(s) and allows the system to start normally when an occupied command is received.OAT SensorIf the outdoor air temperature sensor (OAT) fails (analog input MCB-AI5 open or short-circuited) and it is not acting as the “Control Temperature” (CtrlTemp Src= parameter is not set to “OAT”), the OAT Sensor problem occurs.When the OAT Sensor problem occurs, the unit continues to operate with the following modifications:1. Discharge temperature set point reset based on outdoor

air is unavailable.2. Compressor low ambient lockout is disabled.3. High ambient heating lockout is disabled.4. Purge operation is disabled.

When the alarm condition is no longer present, the OAT Sen-sor problem automatically clears.

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Space SensorIf the optional space temperature sensor ZNT1 fails (analog input MCB-AI1 open or short-circuited) on a unit equipped with a return air temperature sensor, the Space Sensor prob-lem occurs as long as the Space Sensor= parameter in the Unit Configuration menu is set to “Yes.” If this parameter is set to “No” the Space Sensor problem indication is disabled.When the Space Sensor problem occurs, the unit continues to operate with the following modifications:1. Discharge temperature set point reset based on space

temperature is unavailable.2. Purge operation is disabled. 3. If the space temperature input is acting as the “Control

Temperature” (CtrlTemp Src= parameter is set to “Space”), the controller automatically changes the Ctr-lTemp Src= parameter to “Return” (if the unit is equipped with a functioning return air sensor).

When the Space Sensor problem occurs during an unoccu-pied time period, the unit starts and runs continuously in the UnocHtg operating state, using the return air temperature sensor as the “Control Temperature” if all of the following conditions are true:1. The unit is equipped with a functioning return air tem-

perature sensor.2. The OA Temp= parameter value is below 40°F. 3. The UnoccHtg Spt= parameter in the Zone Heating

menu is set higher than 0°F. When the alarm condition is no longer present, the Space Sensor problem automatically clears and normal unit opera-tion resumes.Return SensorIf the return air temperature sensor (RAT) fails (analog input MCB-AI4 open or short-circuited) while it is not acting as the “Control Temperature” (CtrlTemp Src= parameter is not set to “Return”), the Return Sensor problem occurs.When the Return Sensor problem occurs, the unit continues to operate with the following modifications:1. Discharge temperature set point reset based on return

temperature is unavailable.2. The Hi Return Tmp fault is disabled.

When the alarm condition is no longer present, the Return Sensor problem automatically clears.Ent Fan SensorIf the unit is equipped with an entering fan air temperature sensor (EFT) and it fails (analog input MCB-AI6 open or short-circuited), the Ent Fan Sensor problem occurs as long as the EFT Sensor= parameter in the Unit Configuration menu is set to “Yes.” If this parameter is set to “No” the Ent Fan Sensor problem indication is disabled.

When the Ent Fan Sensor problem occurs, the unit continues to operate with the following modifications.1. The Low Airflow problem alarm is disabled.2. The function on gas or electric heat units that limits the

Eff Htg Spt= parameter in the Discharge Heating menu based the maximum heat rise for the heat exchanger on units equipped with gas or electric heat is disabled. Refer to “Heating: Multistage” on page 83 (electric heat units) or “Gas Heat” on page 86 (gas heat units).

When the alarm condition is no longer present, the Ent Fan Sensor problem automatically clears.

Note: Note that the EFT sensor is only provided with units that have gas or electric heat.

Low AirflowThe Low Airflow problem is a safety designed to protect the electric heater on a unit equipped with multistage electric heat.The Low Airflow problem occurs on units equipped with multistage electric heat if communication is lost between the main controller (MCB) and the electric heat control board (EHB1) and the temperature rise across the heater exceeds 60°F or the discharge air temperature exceeds 145°F. When the Low Airflow problem occurs, the unit continues to operate but the heating system is disabled. It remains dis-abled until the Low Airflow problem is manually cleared through the unit keypad or via a network signal.The controller determines the temperature rise across the heater by subtracting the Ent Fan= value from the Disch Temp= value. Heat FailIf a unit is equipped with a gas furnace (one-stage or modu-lating) and the burner flame safeguard (FSG) control enters the “safety lockout” state after a call for heat, relay R24 energizes and closes a set of contacts and delivers a binary input (binary input MCB-BI5 on) to the controller. When this binary input is present the Heat Fail problem occurs.When the Heat Fail problem occurs, the unit continues to operate with the heating system disabled by the FSG. Heat-ing remains disabled until the flame safeguard control is manually reset. When the FSG is reset, relay R24 de-ener-gizes, removing the binary input (binary input MCB-BI5 off) from the controller, causing the Heat Fail problem to auto-matically clear.For detailed information regarding the FSG control, refer to the separate installation manual supplied with the gas fur-nace and the “Sequences of Operation” section of the model-specific installation manual (refer to Table 1 on page 3).

100 McQuay OM 138-3

Hi Pres-Ckt1This alarm occurs on units equipped with compressorized cooling only. If either of the cooling circuit #1 high pressure switches (HP1 or HP3) opens (binary input CCB1-BI7 off), indicating a high refrigerant pressure situation, the Hi Pres-Ckt1 problem occurs.When the Hi Pres-Ckt1 problem occurs, the unit continues to operate but cooling circuit #1 is disabled. Circuit #1 remains disabled until both high pressure switches are closed and the Hi Pres-Ckt1 problem is manually cleared through the unit keypad or via a network signal.Hi Pres-Ckt2This alarm occurs on units equipped with compressorized cooling only. If either of the cooling circuit #2 high pressure switches (HP2 or HP4) opens (binary input CCB2-BI7 off) indicating a high refrigerant pressure situation, the Hi Pres-Ckt2 problem occurs.When the Hi Pres-Ckt2 problem occurs, the unit continues to operate but cooling circuit #2 is disabled. Circuit #2 remains disabled until both high pressure switches are closed and the Hi Pres-Ckt2 problem is manually cleared through the unit keypad or via a network signal.Lo Pres-Ckt1This alarm occurs on units equipped with compressorized cooling only. When a call is made for circuit #1 operation, if the cooling circuit #1 low pressure switch (LP1) remains open (input removed from CCB1-BI6) beyond a “low pres-sure time period” after the circuit #1 liquid line solenoid is opened, the Lo Pres-Ckt1 problem occurs. The alarm also occurs any time the circuit is operating if LP1 opens. If the unit is configured for low ambient condenser operation and the OA Temp= parameter value is below 45°F, the “low pres-sure time period” is 165 seconds. Otherwise the “low pres-sure time period” is 45 seconds.When the Lo Pres-Ckt1 problem occurs, the unit continues to operate but cooling circuit #1 is disabled. Circuit #1 remains disabled for at least one cooling stage time period. After the cooling stage time period expires, the alarm auto-matically clears and the circuit is re-enabled. If the Lo Pres-Ckt1 problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automati-cally clear the third time but must be manually cleared through the unit keypad or via a network signal. Lo Pres-Ckt2This alarm occurs on units equipped with compressorized cooling only. When a call is made for circuit #2 operation, if the cooling circuit #2 low pressure switch (LP2) remains open (binary input CCB2-BI6 off) beyond a “low pressure time period” after the circuit #2 liquid line solenoid is opened, the Lo Pres-Ckt2 problem occurs. The alarm also occurs any time after the circuit is operating if LP2 opens. If

the unit is configured for low ambient condenser operation and the OA Temp= parameter value is below 45°F, the “low pressure time period” is 165 seconds. Otherwise the “low pressure time period” is 45 seconds.When the Lo Pres-Ckt2 problem occurs, the unit continues to operate but cooling circuit #2 is disabled. Circuit #2 remains disabled for at least one cooling stage time period. After the cooling stage time period expires, the alarm auto-matically clears and the circuit is re-enabled. If the Lo Pres-Ckt2 problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automati-cally clear the third time but must be manually cleared through the unit keypad or via a network signal. Frost-Ckt1This alarm occurs on units equipped with compressorized cooling without hot gas bypass operation only. If the circuit #1 frost protection switch (FP1) opens (binary input CCB1-BI8 off) while a compressor on cooling circuit #1 has been on for at least two minutes and the circuit #1 liquid line sole-noid valve (SV1) is open, the Frost-Ckt1 problem occurs. This indicates a cold refrigerant temperature exists at the unit evaporator coil on circuit #1, creating the possibility of frost build-up on the coil.When the Frost-Ckt1 problem occurs, the unit continues to operate but cooling circuit #1 is disabled. Circuit #1 remains disabled for at least one cooling stage time period. After the cooling stage time period expires, the alarm automatically clears and the circuit is re-enabled. If the Frost-Ckt1 problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal. Frost-Ckt2This alarm occurs on units equipped with compressorized cooling without hot gas bypass operation only. If the circuit #2 frost protection switch (FP2) opens (binary input CCB2-BI8 off) while a compressor on cooling circuit #2 has been on for at least two minutes and the circuit #2 liquid line sole-noid valve (SV2) is open, the Frost-Ckt2 problem occurs. This indicates a cold refrigerant temperature exists at the unit evaporator coil on circuit #2, creating the possibility of frost build-up on the coil.When the Frost-Ckt2 problem occurs, the unit continues to operate but cooling circuit #2 is disabled. Circuit #2 remains disabled for at least one cooling stage time period. After the cooling stage time period expires, the alarm automatically clears and the circuit is re-enabled. If the Frost-Ckt2 problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal.

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Comp #1 AlmThis alarm occurs only on units equipped with compres-sorized cooling. If compressor #1 has been commanded on for longer than ten seconds and the compressor #1 input to the compressor control board is off (binary input CCB1-BI9 off), the Comp #1 Alm problem occurs as long as the circuit is not off on a high pressure alarm. The compressor #1 input is delivered to the compressor control board through an aux-iliary switch on the compressor #1 contactor. Therefore, precisely speaking, the alarm indicates that the controller commanded the compressor to start but the contactor did not pull in. When the unit is equipped with a compressor #1 oil pressure switch (OP1) and/or a compressor #1 external motor protector (MP1), this condition normally occurs when either MP1or OP1 trip. If the unit is equipped with neither MP1 nor OP1, this alarm simply indicates the contactor did not pull in for electrical or mechanical reasons.1

When the Comp 1 Alm problem occurs, the unit continues to operate but compressor #1 is disabled. Compressor #1 remains disabled for 35 minutes after which the alarm auto-matically clears and the compressor is re-enabled. The con-troller can then attempt to start compressor #1 again when required. If the Comp 1 Alm problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal.2

Note: The OP1 device itself requires a manual reset once it trips. The MP1 device automatically resets when the compressor motor windings cool.

Comp #2 AlmThis alarm occurs only on units equipped with compres-sorized cooling. If compressor #2 has been commanded on for longer than ten seconds and the compressor #2 input to the compressor control board is off (binary input CCB2-BI9 off), the Comp #2 Alm problem occurs as long as the circuit is not off on a high pressure alarm. The compressor #2 input is delivered to the compressor control board through an aux-

iliary switch on the compressor #2 contactor. Therefore, precisely speaking, the alarm indicates that the controller commanded the compressor to start but the contactor did not pull in. When the unit is equipped with a compressor #2 oil pressure switch (OP2) and/or a compressor #2 external motor protector (MP2), this condition normally occurs when either MP2 or OP2 trip. If the unit is equipped with neither MP2 nor OP2, this alarm simply indicates the contactor did not pull in for electrical or mechanical reasons.1

When the Comp #2 Alm problem occurs, the unit continues to operate but compressor #2 is disabled. Compressor #2 remains disabled for 35 minutes after which the alarm auto-matically clears and the compressor is re-enabled. The con-troller can then attempt to start compressor #2 again when required. If the Comp #2 Alm problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal.1


Comp #3 AlmThis alarm occurs only on units equipped with compres-sorized cooling. If compressor #3 has been commanded on for longer than ten seconds and the compressor #3 input to the compressor control board is off (binary input CCB1-BI10 off), Comp #3 Alm problem occurs as long as the cir-cuit is not off on a high pressure alarm. The compressor #3 input is delivered to the compressor control board through an auxiliary switch on the compressor #3 contactor. Therefore, precisely speaking, the alarm indicates that the controller commanded the compressor to start but the contactor did not pull in. When the unit is equipped with a compressor #3 oil pressure switch (OP3) and/or a compressor #3 external motor protector (MP3), this condition normally occurs when either MP3 or OP3 trip. If the unit is equipped with neither MP3 nor OP3, this alarm simply indicates the contactor did not pull in for electrical or mechanical reasons1.When the Comp #3 Alm problem occurs, the unit continues to operate but compressor #3 is disabled. Compressor #3 remains disabled for 35 minutes after which the alarm auto-matically clears and the compressor is re-enabled. The con-troller can then attempt to start compressor #3 again when required. If the Comp #3 Alm problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal.1


1. Unit models 018 through 060 are equipped with scroll com-pressors. Unit models 070 and 075 are optimally equipped with scroll compressors. Oil pressure switches are not used on these units. Also, some scroll compressor sizes are equipped with internal motor protection. In these cases, external motor protectors are not used. These include Comp #1 on unit models 018 through 036, Comp #3 on unit models 025 through 036 and Comp2 on unit model 018.

2. Unit models 018 through 060 are equipped with scroll com-pressors. Unit models 070 and 075 are optimally equipped with scroll compressors. Oil pressure switches are not used on these units. Also, some scroll compressor sizes are equipped with internal motor protection. In these cases, external motor protectors are not used. These include Comp #1 on unit models 018 through 036, Comp #3 on unit models 025 through 036 and Comp2 on unit model 018.

102 McQuay OM 138-3

Comp #4 AlmThis alarm occurs only on units equipped with compres-sorized cooling. If compressor #4 has been commanded on for longer than ten seconds and the compressor #4 input to the compressor control board is off (binary input CCB2-BI10 is off), the Comp #4 Alm problem occurs as long as the circuit is not off on a high pressure alarm. The compressor #4 input is delivered to the compressor control board through an auxiliary switch on the compressor #4 contactor. There-fore, precisely speaking, the alarm indicates that the control-ler commanded the compressor to start but the contactor did not pull in. When the unit is equipped with a compressor #4 oil pressure switch (OP4) and/or a compressor #4 external motor protector (MP4), this condition normally occurs when either MP4or OP4 trip. If the unit is equipped with neither MP4 nor OP4, this alarm simply indicates the contactor did not pull in for electrical or mechanical reasons.1

When the Comp #4 Alm problem occurs, the unit continues to operate but compressor #4 is disabled. Compressor #4 remains disabled for 35 minutes after which the alarm auto-matically clears and the compressor is re-enabled. The con-troller can then attempt to start compressor #4 again when required. If the Comp #4 Alm problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal.1


Comp 5 AlmThis alarm occurs only on units equipped with compres-sorized cooling. If compressor # 5 has been on form longer than ten seconds and the compressor #5 input to the com-pressor control board is off (binary input CCB1-BI1 off), the Comp 5 Alm problem occurs as long as the circuit is not off on a high pressure alarm. The compressor #5 input is deliv-ered to the compressor control board through an auxiliary switch on the compressor #5 contactor. Therefore, precisely speaking, the alarm indicates that controller commanded the compressor to start but the contactor did not pull in. This condition normally occurs when the external motor protector MP5 trips. When the Comp 5 Alm problem occurs, the unit continues to operate but compressor # 5 is disabled. Compressor # 5 remains disabled for 35 minutes after which the alarm auto-matically clears and the compressor is re-enabled. The con-troller can then attempt to start compressor #5 again when required. If the Comp 5 Alm problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal.

Comp 6 AlmThis alarm occurs only on units equipped with compres-sorized cooling. If compressor # 6 has been on form longer than ten seconds and the compressor #6 input to the com-pressor control board is off (binary input CCB2-BI1 off), the Comp 6 Alm problem occurs as long as the circuit is not off on a high pressure alarm. The compressor #6 input is deliv-ered to the compressor control board through an auxiliary switch on the compressor #6 contactor. Therefore, precisely speaking, the alarm indicates that controller commanded the compressor to start but the contactor did not pull in. This condition normally occurs when the external motor protector MP6 trips. When the Comp 6 Alm problem occurs, the unit continues to operate but compressor # 6 is disabled. Compressor # 6 remains disabled for 35 minutes after which the alarm auto-matically clears and the compressor is re-enabled. The con-troller can then attempt to start compressor #6 again when required. If the Comp 6 Alm problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal.Ckt1 Clg EnaWhen a unit is equipped with compressorized cooling, the main control board (MCB) controls the cooling outputs on and receives cooling circuit input information from the circuit #1 compressor control board (CCB1) via an RS485 communication interface between the two boards. If the MCB board detects a loss of communication between the two boards there must be an external method for the MCB to command the CCB1 board to shut off the cooling on that circuit. On units equipped with an air-cooled condenser, this is accomplished with a “cooling enable” output from MCB (MCB-BO7) hard wired directly to a “cooling enable” input to the CCB1 board (CCB1-BI12).On units equipped with an evaporative condenser, this is accomplished indirectly with a “cooling enable” output from MCB (MCB-BO7) that turns the evaporative condenser sump pump on and an auxiliary switch on the pump contac-tor delivers the “cool enable” input to the CCB1 board (CCB1-BI12).If the MCB board is communicating with the CCB1 board and the “cooling enable” output from MCB is on but the “cooling enable” input to CCB1 remains off the Ckt1 Clg Ena problem will occur. This indicates either a problem with the evaporative condenser sump pump or the sump water level.When the Ckt1 Clg Ena problem occurs, cooling circuit #1 is disabled. Cooling circuit #1 remains disabled until the prob-lem is corrected and the Ckt1 Clg Ena problem is manually cleared through the unit keypad or via a network signal.

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Ckt2 Clg EnaWhen a unit is equipped with compressorized cooling, the main control board (MCB) controls the cooling outputs on and receives cooling circuit input information from the circuit #2 compressor control board (CCB2) via a RS485 communication interface between the two boards. If the MCB board detects a loss of communication between the two boards there must be an external method for the MCB to command the CCB2 board to shut off the cooling on that circuit. On unit equipped with an air-cooled condenser, this is accomplished with a “cooling enable” output from MCB (MCB-BO7) hard wired directly to a “cooling enable” input to the CCB2 board (CCB2-BI12).On units equipped with an evaporative condenser, this is accomplished indirectly with a “cooling enable” output from MCB (MCB-BO7) that turns the evaporative condenser sump pump on and an auxiliary switch on the pump contac-tor delivers the “cool enable” input to the CCB2 board (CCB2-BI12).If the MCB board is communicating with the CCB2 board and the “cooling enable” output from MCB is on but the “cooling enable” input to CCB2 remains off the Ckt2 Clg Ena problem will occur. This indicates either a problem with the evaporative condenser sump pump or the sump water level.When the Ckt2 Clg Ena problem occurs, cooling circuit #2 is disabled. Cooling circuit #2 remains disabled until the prob-lem is corrected and the Ckt2 Clg Ena problem is manually cleared through the unit keypad or via a network signal.GenC Clg EnaWhen a unit is equipped with a DX cooling coil and is inter-faced with a field supplied condensing unit; it is equipped with a generic condenser control board for controlling the field supplied condensing unit (GCB1). The main control board (MCB) controls the cooling outputs on the generic condenser control board via an RS485 communication bus interface between the two boards. If the MCB detects a loss of communication there must be an external method for the MCB to command the GCB1 board to shut off the cooling. This is accomplished with a “cooling enable” output from MCB (MCB-BO7) hard wired to a “cooling enable” input to the GCB1 board (binary input GCB1-BI12).If the MCB is communicating with the GCB1 board and the “cooling enable” output from MCB is on but the “cooling enable” input to GCB1 remains off, indicating a wiring prob-lem between the boards, the GenC Clg Ena problem occurs.When the GenC Clg Ena problem occurs, cooling is dis-abled. Cooling remains disabled until the problem is cor-rected and the GenC Clg Ena problem is manually cleared through the unit keypad or via a network signal.

HtgB Htg EnaWhen a unit is equipped with multi-stage electric heat, it is equipped with an electric heat control board for controlling the heat (EHB1). The main control board (MCB) controls the heating outputs on the electric heat control board via an RS485 bus interface between the two boards. If the MCB detects a loss of communication there must be an external method for the MCB to command the EHB1 board to shut off the heating. This is accomplished with a “heating enable” output from MCB (MCB-BO11) hard wired to a “heating enable” input to the EHB1 board (EHB1-BI12).If the MCB is communicating with the EHB1 board and the “heating enable” output from MCB is on but the “heating enable” input to EHB1 remains off, indicating a wiring prob-lem between the boards, the HtgB Htg Ena problem occurs.When the HtgB Htg Ena problem occurs, heating is disabled. Heating remains disabled until the problem is corrected and the HtgB Htg Ena problem is manually cleared through the unit keypad or via a network signal.Ckt1 Comm FailWhen a unit is equipped with compressorized cooling, the main control board (MCB) controls the cooling outputs on and receives cooling circuit input information from the cir-cuit #1 compressor control board (CCB1) via an RS485 bus interface between the two boards. If the MCB detects a loss of communication between the two boards, the Ckt1 Comm Fail problem occurs.When the Ckt1 Comm Fail problem occurs while the unit is not in the Cooling operating state, the unit is allowed to enter the Cooling operating state as long as the MCB is communi-cating with the circuit #2 cooling control board (CCB2). In this case the cooling capacity is limited to that available from circuit #2. If the MCB is not communicating with either cooling control board (CCB1 or CCB2), the unit is not allowed to enter the Cooling operating state.When the Ckt1 Comm Fail problem occurs while the unit is in the Cooling operating state, the unit remains in the Cool-ing operating state. However, the maximum cooling capacity is limited to that of circuit #2 if the MCB is communicating with the circuit #2 cooling control board (CCB2). If the MCB is not communicating with either cooling control board (CCB1 or CCB2), the current cooling capacity in the MCB is set to 0%. Any cooling that may be operating at the time of the communication failure remains on (on either cir-cuit) until the MCB leaves the Cooling operating state due to normal operation. When the MCB leaves the Cooling operat-ing state the “cooling enable” output (MCB-BO7) is turned off and, therefore, the “cooling enable” input to the CCB1 and CCB2 boards is removed (binary inputs CCB1-BI12 and CCB2-BI12 off) and this causes the CCB1 and CCB2 to completely stage off all cooling. The MCB then does not re-enter the Cooling operating state until communication is re-established with at lease one cooling control board. When communications between the MCB and CCB1 is re-estab-lished, the Ckt1 Comm Fail problem automatically clears.

104 McQuay OM 138-3

Ckt2 Comm FailWhen a unit is equipped with compressorized cooling, the main control board (MCB) controls the cooling outputs on and receives cooling circuit input information from the cir-cuit #2 compressor control board (CCB2) via an RS485 bus interface between the two boards. If the MCB detects a loss of communication between the two boards, the Ckt2 Comm Fail problem occurs.When the Ckt2 Comm Fail problem occurs while the unit is not in the Cooling operating state, the unit is allowed to enter the Cooling operating state as long as the MCB is communi-cating with the circuit #1 cooling control board (CCB1). In this case the cooling capacity is limited to that available from circuit #1. If the MCB is not communicating with either cooling control board (CCB1 or CCB2), the unit is not allowed to enter the Cooling operating state.When the Ckt2 Comm Fail problem occurs while the unit is in the Cooling operating state, the unit remains in the Cool-ing operating state. However, the maximum cooling capacity is limited to that of circuit #1 if the MCB is communicating with the circuit #1 cooling control board (CCB1). If the MCB is not communicating with either cooling control board (CCB1 or CCB2), the current cooling capacity in the MCB is set to 0%. Any cooling that may be operating at the time of the communication failure remains on (on either cir-cuit) until the MCB leaves the Cooling operating state due to normal operation. When the MCB leaves the Cooling operat-ing state the “cooling enable” output (MCB-BO7) is turned off and, therefore, the “cooling enable” input to the CCB1 and CCB2 boards is removed (binary inputs CCB1-BI12 and CCB2-BI12 off) and this causes the CCB1 and CCB2 to completely stage off all cooling. The MCB then does not re-enter the Cooling operating state until communication is re-established with at lease one cooling control board. When communications between the MCB and CCB2 is re-estab-lished, the Ckt2 Comm Fail problem automatically clears.GenC Comm FailWhen a unit is equipped with a DX cooling coil and is inter-faced with a field supplied condensing unit; it is equipped with a generic condenser control board (GCB1) for control-ling the field supplied condensing unit. The main control board (MCB) controls the cooling outputs on the generic condenser control board via an RS485 bus interface between the two boards. If the MCB detects a loss of communication between the two boards, the GenC Comm Fail problem occurs.When the GenC Comm Fail problem occurs while the unit is not in the Cooling operating state, the unit is not allowed to enter the Cooling operating state.When the GenC Comm Fail problem occurs while the unit is in the Cooling operating state, the unit remains in the Cool-ing operating state. However, the current cooling capacity in

the MCB is set to 0%. Any cooling that may be operating at the time of the communication failure remains on until the MCB leaves the Cooling operating state due to normal oper-ation. When the MCB leaves the Cooling operating state the “cooling enable” output (MCB-BO7) is turned off and, therefore, the “cooling enable” input to the GCB1 board is removed (binary input GCB1-BI12 off) and this causes the GCB1 to completely stage off all cooling. The MCB then does not re-enter the Cooling operating state until communi-cation is re-established with the cooling control board (GCB1). When communications between the MCB and GCB1 is re-established, the GenC Comm Fail problem auto-matically clears.HtgB Comm FailWhen a unit is equipped with multi-stage electric heat, it is equipped with an electric heat control board for controlling electric heat (EHB1). The main control board (MCB) con-trols the heating outputs on the electric heat control board via an RS485 bus interface between the two boards. If the MCB detects a loss of communication between the two boards, the HtgB Comm Fail problem occurs.When the HtgB Comm Fail problem occurs while the unit is not in a heating operating state, the unit is not allowed to enter the a heating operating state.When the HtgB Comm Fail problem occurs while the unit is in a heating operating state, the unit remains in the heating operating state. However, the current heating capacity in the MCB is set to 0%. Any heating that may be operating at the time of the communication failure remains on until the MCB leaves the Heating operating state due to normal operation. When the MCB leaves the heating operating state the “heat-ing enable” output (MCB-BO11) is turned off and, therefore, the “heating enable” input to the EHB1 board is removed (binary input EHB1-BI12 off) and this causes the EHB1 to completely stage off all heating. The MCB then does not re-enter any heating operating state until communication is re-established with the cooling control board (EHB1). When communications between the MCB and EHB1 is re-estab-lished, the HtgB Comm Fail problem automatically clears.ERecB Comm FailWhen a unit is equipped with an energy recovery wheel, it is equipped with an energy recovery control board for control-ling the energy recovery wheel (ERB1). The main control board (MCB) controls the energy recovery outputs on the energy recovery control board via an RS485 bus interface between the two boards. If the MCB detects a loss of com-munication between the two boards, the ERecB Comm Fail problem occurs.When the ERecB Comm Fail problem occurs, the energy recovery system is disabled. When communications between the MCB and EHB1 is re-established, the ERecB Comm Fail problem automatically clears.

McQuay OM 138-3 105

WarningsPumpdown-Ckt1When a unit is configured to control an air-cooled condenser, the Pumpdown-Ckt1 warning occurs if the circuit #1 low pressure switch (LP1) fails to open (binary input CCB1-BI6 off) within 180 seconds of the liquid line solenoid valve SV1 closing when a circuit is pumped down.When the Pumpdown-Ckt1 warning occurs, the unit operation is not affected. When the condition is corrected, the Pumpdown-Ckt1 warning must be manually cleared through the unit keypad or via a network signal.Pumpdown-Ckt2When a unit is configured to control an air-cooled condenser, the Pumpdown-Ckt2 warning occurs if the circuit #2 low pressure switch (LP2) fails to open (binary input CCB2-BI6 off) within 180 seconds of the liquid line solenoid valve SV2 closing when a circuit is pumped down.When the Pumpdown-Ckt2 warning occurs, the unit operation is not affected. When the condition is corrected, the Pumpdown-Ckt2 warning must be manually cleared through the unit keypad or via a network signal.Airflow SwitchIf the unit has been in the Off operating state for at least thirty minutes and the PC7 airflow switch input to the main controller indicates airflow (binary input MCB-BI6 on), the

Airflow Switch warning occurs. This normally indicates a problem with the PC7 airflow switch.When the Airflow Switch warning occurs, unit operation is not affected. When the alarm condition is corrected, the Air-flow Switch warning must be manually cleared through the unit keypad or via a network signal.Dirty FilterIf the pressure drop across the first filter section in the unit exceeds the setting of the PC5 differential pressure switch while the unit is operational, the dirty first filter input is removed from MCB (binary input MCB-BI9 off) and the Dirty Filter warning occurs.When the Dirty Filter warning occurs, unit operation is not affected. The Dirty Filter warning must be manually cleared through the unit keypad or via a network signal.Dirty FnlFltrIf the pressure drop across the final filter section in the unit exceeds the setting of the PC6 differential pressure switch while the unit is operational, the dirty final filter input is removed from MCB (binary input MCB-BI10 off) and the Dirty FnlFltr warning occurs.When the Dirty FnlFltr warning occurs, unit operation is not affected. The Dirty FnlFltr warning must be manually cleared through the unit keypad or via a network signal.

106 McQuay OM 138-3

MicroTech II DDC FeaturesThe MicroTech II unit controller uses PID control algorithms (referred to as “PID objects”) to control modulating output devices in order to keep a controlled variable at or near the desired set point. These devices are generally either floating-point actuators or variable frequency motor drives (VFD). There is a pair of outputs defined for each modulating device to be controlled. One output energizes to increase the capac-ity and the other energizes to decrease the capacity of the modulating device. There are two different PID controls schemes used to control the modulating output devices. These are the “Direct PID Method” and the “Cascaded PID Method.” The “Direct PID Method” uses one Velocity PID object to directly control the modulating device outputs. The “Cascaded PID Method” uses one Position PID and one Velocity PID object in a “cascaded” manner to control the modulating device outputs.

Direct PID MethodIn some cases, the controller uses a Velocity PID object directly to turn actuator control outputs on and off to main-tain a controlled variable at a set point. In these cases the set point and current value of the controlled variable are input to the Velocity PID object. The Velocity PID object determines a “time on” for either the increase or decrease output as nec-essary to reduce the “error” between the set point and the controlled variable. This information is input into a position adjust output object (PAO) which in turn commands the out-put device increase or decrease output on and off, reposition-ing the actuator.

Note: In this method, position feedback from the control actuators is not used for control purposes.

Table 64 on page 108 lists the modulating devices controlled using this method. Figure 10 is a schematic representation of this control scheme.

Cascaded PID MethodIn some cases, the controller uses actuator position (or VFD speed) feedback and a combination of a Position PID object and a Velocity PID object to control actuator (or VFD) con-trol outputs to maintain a controlled variable at a set point. In this “cascaded” control scheme, the set point and the current value of the controlled variable are input to the Position PID object. The Position PID object then calculates a new actua-tor position (or VFD speed) set point and inputs this into the Velocity PID object. The Velocity PID object then compares the current actuator position (or VFD speed) feedback signal to the new position set point and determines a “time on” for either the increase or decrease output as necessary to main-tain the feedback signal at the current position (or speed) set point. This information is input into a position adjust output object (PAO) which in turn commands the output device increase or decrease output on and off, repositioning the actuator (or changing VFD speed).Table 64 on page 108 lists the modulating devices controlled using this method. Figure 11 is a schematic representation of this control scheme.

Figure 10:Direct PID Method Control Scheme

Figure 11:Cascaded PID Method Control Scheme

+-

Velocity PID

ControlledVariable

Set Point PAOActuatorPosition

+-

Velocity PID

ControlledVariable

Set Point PAOActuator orVFD Position

+-

Position PID

Actuator Position (or VFD Speed) Feedback

McQuay OM 138-3 107

PID Control ParametersAssociated with each modulating output device, there is a set of three adjustable PID control parameters. These are the Period, Proportional Band and Integral Time.

Note: Since derivative control is not generally required in HVAC control strategies, the Derivative Time parameter of the PID object is set to 0 and is not adjustable through the unit keypad/display. The Derivative Time parameter can only be adjusted using the MicroTech II Service Tool.

Since the factory settings for these parameters should pro-vide the best control action, field changes are not recom-mended. If problems arise, these parameters should first be set back to the factory settings if they have been changed in the field. If adjustment is then required, caution should be used since parameters grossly out of adjustment can cause erratic unit operation and possible equipment damage. Changes should only be made in small increments and to only one parameter at a time. After each change, enough time for the system to stabilize should be allowed before fur-ther changes are made. Refer to the following sections for guidelines regarding how the specific parameters affect the control action of the PID algorithm.

PeriodUnless grossly misadjusted, changing the Period parameter generally has a relatively small effect on the PID control action. It should generally be set to a value of the same mag-nitude and within 1/4 to 2/3 the time constant of the system

being controlled. If the Period is set too long, loss of system control will likely occur. If the Period is set too short, dra-matic system “hunting” will likely occur. When in doubt, this parameter should be set to the factory default setting.

Note: The Period parameter is not allowed to be set higher than the Integral Time parameter. If this is attempted the Period parameter reverts to its previ-ous setting.

Proportional Band and Integral TimeThe Proportional Band and the Integral Time parameters have a similar effect on the PID control action. Increasing either the Proportional Band or the Integral Time has a slow-ing effect on the control action. Decreasing either the Pro-portional Band or the Integral Time has a speeding effect on the control action. Increasing or decreasing both parameters at the same time has a more dramatic slowing or speeding effect. Increasing one while decreasing the other tends to have countering effects on the control action. Therefore, if it becomes necessary to slow down or speed the control action, these two parameter should generally not both be changed at the same time. One parameter should remain unchanged while the other is increased or decreased. Proper “tuning” of the Proportional Band and the Integral Time parameters involves finding an acceptable “balance” between the two.

Note: The Integral Time parameter is not allowed to be set lower than the Period parameter. If this is attempted the Integral Time parameter reverts to its previous setting.

Table 64: MicroTech II Modulating Output Devices

Modulating Device Decrease Binary Output Increase Binary Output PID Method Controlled Variable

Hot Water Valve Actuator MCB-BO9 MCB-BO10 Direct Discharge Temperature

Steam Valve Actuator MCB-BO9 MCB-BO10 Direct Discharge Temperature

Gas Valve Actuator MCB-BO9 MCB-BO10 Direct Discharge Temperature

Chilled Water Valve Actuator MCB-BO7 MCB-BO8 Direct Discharge Temperature

Heating F&BP Actuator MCB-BO9 MCB-BO10 Direct Discharge Temperature

Cooling F&BP Actuator MCB-BO7 MCB-BO8 Direct Discharge Temperature

Economizer Damper Actuator MCB-BO5 MCB-BO6 Cascaded Discharge Temperature

Return/Exhaust Fan Inlet Vane Actuator or VFD MCB-BO15 MCB-BO16 Cascaded Building Static Pressure

Effective Discharge Cooling Set Point — — Direct Control Temperature

Effective Discharge Heating Set Point — — Direct Control Temperature

108 McQuay OM 138-3

Adjusting PID Control ParametersCorrecting System Instability (“Hunting”)If the system control is unstable (“hunting”), this generally means the control response is too “fast.” To correct system “hunting”, generally the first step is to slow down the response by increasing the Integral Time until the system becomes stable. This may, however, cause “sluggishness” in the controlled variable approach to the set point during tran-sient conditions (such as at unit start up).1 If system “slug-gishness” occurs after the Integral Time is adjusted, it means the overall control response is now too “slow”. The response can be speeded up by reducing the Proportional Band. When the Proportional band is changed so that the controlled vari-able approach to the set point is acceptable, it may then be necessary to readjust the Integral Time to re-stabilize the control action.When in doubt, these parameters should be set to the factory default setting.

Correcting System “Sluggishness”If the system control is “sluggish”, meaning in the controlled variable approach to the set point during transient conditions (such as at unit start up) is too slow, this generally means the overall control response is too “slow.”2 To correct system “sluggishness”, the first step is to speed up the overall sys-tem response by decreasing the Proportional Band so that the controlled variable approach to the set point is acceptable. This may, however, result in system instability (“hunting”). If system instability occurs, the Integral Time should be increased to slow down the control response and stabilize the control action.When in doubt, these parameters should be set to the factory default setting.

PRAC Tuning

In the event that PID parameters do need adjustment, an automatic tuning function called PRAC (pattern recognition adaptive control) is available for several of the MicroTech II control loops. These PRAC functions can be used in lieu of manually adjusting the various PID proportional band and integral time control parameters.To use the PRAC feature to tune the duct static pressure con-trol PID parameters, for example, change the Duct Static Pressure Control PRAC Flag from No to Yes. Then allow the unit to control the duct static pressure in the normal manner. The PRAC function requires a “history” and it may take sev-eral excursions (perhaps as many as 10) above and below set point for the new proportional band and integral settings to be determined and for the control to settle out.

Note: After using the PRAC function, the new propor-tional band and integral settings do not appear on the unit keypad until power is subsequently cycled to the unit controller.

1. Once operating, the system can be checked for sluggish-ness by changing the set point and measuring the time it takes for the controlled variable to reach the set point.

2. Once operating, the system can be checked for sluggish-ness by changing the set point and measuring the time it takes for the controlled variable to reach the set point


Keypad/Display ID Parameter Name

Menu Name Menu Item

Duct Static P Setup PRAC= No Duct Static Pressure Control PRAC Flag

Bldg Static P Setup PRAC= No Building Static Pressure Control PRAC Flag

Chilled Water Setup PRAC= No Chilled Water Control PRAC Flag

Economizer Setup PRAC= No Economizer Control PRAC Flag

Heating Setup PRAC= No Heating Control PRAC Flag

CAUTIONGrossly misadjusting PID parameters can cause erratic unit operation and equipment damage.

PID control parameters should only be adjusted by trained personnel having a thorough under-standing of how the parameters affect overall system operation. Generally these parameters do not need to be adjusted from the factory default settings.

McQuay OM 138-3 109

Software Identification and Configuration

Software IdentificationThe MicroTech II control system code is made up of up to four different software components. All unit applications include a main control board application code component that resides in the main control board (MCB). Then, depend-ing on the unit configuration, there may be one or two cool-ing auxiliary control boards, an electric heat auxiliary control board or an energy recovery auxiliary control board each loaded with an application code component. The application code in the main control board and any aux-iliary control boards are each assigned a ten-digit software identification number. This includes a seven-digit base num-ber, followed by a three-digit version number. The software identification numbers that the unit was loaded with at the factory can be determined from a software identi-fication label located near the keypad/display. Figure 12 shows a typical software identification label. The box labeled “UNIT SOFTWARE NUMBER” contains the soft-ware identification number for the code in the main control-ler (MCB). The box labeled “COMPRESSOR SOFTWARE” contains the software identification number for the code in the auxiliary cooling control board(s) (CCB1, CCB2 and GCB1) when applicable. The box labeled “STAGE ELEC HEAT SOFTWARE” contains the software identification number for the code in the auxiliary electric heat control board (EHB1) when applicable. The box labeled “ENERGY RECOVERY SOFTWARE” contains the software identifica-tion number for the code in the auxiliary energy recovery control board (ERB1) when applicable.

Identifying Application Code Using Unit Keypad/DisplayThe software identification number for the application cur-rently loaded into the main control board (MCB) can be determined by viewing the AHU ID= parameter in the Unit Configuration menu on the unit keypad/display. The entire 10 digit “UNIT SOFTWARE NUMBER” is displayed.The software identification number for the application cur-rently loaded into the CCB1 and CCB2 auxiliary cooling control boards can be determined by viewing the CCB1 ID= and CCB2 ID= parameters in the Unit Configuration menu

on the unit keypad/display. Only the 6th through 9th posi-tions of the “COMPRESSOR SOFTWARE” identification number are displayed. For example if a CCB1 board was loaded with version 2506011310 compressor board software, then the CCB1 ID= parameter would display “1131”. If a unit is not equipped with CCB1 and CCB2 boards, the CCB1 ID= and CCB2 ID= parameters will display “???”.The software identification number for the application cur-rently loaded into the GCB1 auxiliary cooling control board can be determined by viewing the GCB1 ID= parameters in the Unit Configuration menu on the unit keypad/display. Note: Only the 6th through 9th positions of the “COMPRES-SOR SOFTWARE” identification number are displayed. For example if a GCB1 board was loaded with version 2506012210 compressor board software, then the GCB1 ID= parameter would display “1221”. If a unit is not equipped with a GCB1 board, the GCB1 ID= parameter will display “???”.The software identification number for the application cur-rently loaded into the EHB1 auxiliary electric heat control board can be determined by viewing the EHB1 ID= parame-ter in the Unit Configuration menu on the unit keypad/dis-play. Note: Only the 6th through 9th positions of the “STAGE ELEC HEAT SOFTWARE” identification number are displayed. For example if a EHB1 board was loaded with version 2506012210 electric heat board software, then the EHB1 ID= parameter would display “1221”. If a unit is not equipped with a EHB1 board, the EHB1 ID= parameter will display “???”.The software identification number for the application cur-rently loaded into the ERB1 auxiliary energy recovery con-trol board can be determined by viewing the ERB1 ID= parameter in the Unit Configuration menu on the unit key-pad/display. Note: Only the 6th through 9th positions of the “ENERGY RECOVERY SOFTWARE” identification num-ber are displayed. For example if a ERB1 board was loaded with version 2506013210 energy recovery board software, then the ERB1 ID= parameter would display “1321”. If a unit is not equipped with a ERB1 board, the ERB1 ID= parameter will display “???”.

110 McQuay OM 138-3

Figure 12:Software Identification Label

Main Control Board (MCB) ConfigurationAfter the main control board software component is loaded into the MCB, it must be “configured” for the specific con-trol application. This consists of setting the value of 20 con-

figuration variables within the MCB. These variables define things such as the type of cooling, number of compressors and cooling stages and the type of heat. If all of these items are not set appropriately for the specific unit, the unit will not function properly. The correct settings for these parame-ters are defined for a given unit by the unit “Software Con-figuration Code”. The “Software Configuration Code” consists of a 26-character string of numbers and letters. The code can be found on the Unit Software Identification Label located on the back side of the door upon which the keypad display is mounted. This label is also shown in Figure 12. Only the first 22 characters of this code are used for software configuration purposes. The first 22 characters of the Software Configuration Code currently loaded into a unit controller can be determine via the unit keypad/display by viewing the six menu items under the Configuration Code menu. The six menu items are Pos # 1-4=, Pos # 5-8=, Pos # 9-12=, Pos # 13-16=, Pos # 17-20= and Pos # 21-22=. The Software Configuration Code in the unit is determined by combining the values of these six parameters. For example, if the six parameters read as fol-lows: Pos # 1-4= 1.178, Pos # 5-8= 0.030, Pos # 9-12= 4.104, Pos # 13-16= 0.221, Pos # 17-20= 0.100 and Pos # 21-22= 2.0, then the Software Configuration Code in the unit is 1178003041040221010020. Note that the decimal points in the values are ignored when constructing the code.Table on page 112 lists the configuration code variables including the position within the code, description of the parameter, and the applicable settings for each. The software default values are shown in bold font.

UNIT SOFTWARE NUMBER

SOFTWARE CONFIGURTION CODE

COMPRESSOR SOFTWARE

STAGE ELEC HEAT SOFTWARE

ENERGY RECOVERY SOFTWARE

UNIT G.O.-SEQ NUMBER

2506010146

11780030411002210100211YYY

2506011310

2506012210

2506013210

728121-050

McQuay OM 138-3 111

Table 66: Software Configuration Code

Configuration Code Position Description Values (Default in Bold)

1 Unit Type

0 RA Zone Control1 RA DAT Control2 100 OA Zone Control3 100 OA DAT Control

2 Cooling Type

0 None1 Compressorized Clg2 Chilled Water (2 Wire FB)A Chilled Water (3 Wire FB)

3 Compressorized Cooling Configuration

0 2 Comp/2 Stage1 2 Comp/3 Stage2 2 Comp/4 Stage3 2 Comp/6 Stage4 3 Comp/4 Stage5 4 Comp/4 Stage6 6 Comp/6 Stage7 4 Comp/8 Stage8 Generic Condenser

4 Generic Condenser Stages 1 – 8 Stages (Default = 8)

5 Low Ambient 0 No1 Yes

61 Condenser Fan Type

0 - No Evap Cond Control1 - 2 Cond Fans/Cir - ABB VFD2 - 2 Cond Fans/Cir - Graham VFD 3 - 2 Cond Fans/Cir - Reliance VFD4 - 2 Cond Fans/Cir - No VFD5 - 3 Cond Fans/Cir - ABB VFD6- 3 Cond Fans/Cir - Graham VFD7 - 3 Cond Fans/Cir - Reliance VFD8 - 3 Cond Fans/Cir - No VFD

7 Damper Type

0 None1 Single Position 30% (2 Wire FB)2 Single Position 100% (2 Wire FB)3 Economizer (2 Wire FB)A Single Position 30% (3 Wire FB)B Single Position 100% (3 Wire FB)C Economizer (3 Wire FB)

8 Design Flow

0 No DesignFlo1 018-030 (800) (Non-Precision PS)2 036-040 (802) (Non-Precision PS)3 045-075 (047) (Non-Precision PS)4 080-135 (077) (Non-Precision PS)A 018-030 (800) (Precision PS)B 036-040 (802) (Precision PS)C 045-075 (047) (Precision PS)D 080-135 (077) (Precision PS)

112 McQuay OM 138-3

1. When downloading code into a unit controller, this position must be 0 if the unit is not equipped with an evaporative condenser. This is true even if the unit Software Identifi-cation Label indicates something other than 0.

Main Control Board (MCB) Data ArchivingAll MCB control parameters and the real time clock settings are backed up by the MCB battery when power is removed from the MCB. In the event of a battery failure, the MCB includes a data archiving function. Once a day, just after midnight, all the MCB control parameter settings are

archived to a file stored in the MCB FLASH memory. If the MCB is powered up with a low or defective battery (or with the battery removed), the most recently archived data is restored to the controller.

Note: When this archived data restoration process occurs, it increases the controller start up and initialization time period by approximately 75 seconds.

9 Heating Type

0 None1 F BP Ctrl2 Multi Staged3 Modulated Gas, 3 – 1 (2 Wire FB)4 Modulated Gas, 20 – 1 (2 Wire FB)5 Steam or Hot Water (2 Wire FB)6 Single Stage Gas7 Single Stage ElectricA Modulated Gas, 3 – 1 (3 Wire FB)B Modulated Gas, 20 – 1 (3 Wire FB)C Steam or Hot Water (3 Wire FB)

10 Max Heating Stages 1 – 8 Stages (Default = 1)11,12 & 13 Max Heat Rise Three Digits (Default = 100)

14 Discharge Fan Type0 Constant Volume1 Variable Inlet Vanes2 Variable Freq Drive

15 Return Fan Type

0 Constant Volume1 Variable Inlet Vanes2 Variable Freq Drive3 No Return Fan4 Propeller Exhaust

16 Return/Exhaust Fan Capacity Control Method

0 None1 Tracking2 Bldg Press3 Position

17 Second Pressure Sensor Type0 None1 Duct2 Bldg

18 Entering Fan Temp Sensor 0 No1 Yes

19 Energy recovery0 None1 Constant Speed Wheel2 Variable Speed Wheel

20 Final Filter 0 No1 Yes

21 Heating Configuration0 Draw Through Preheat1 Draw Through Reheat2 Blow Through

22 Cooling Configuration 0 Draw Through1 Blow Through

Table 66: Software Configuration Code

Configuration Code Position Description Values (Default in Bold)

McQuay OM 138-3 113

TroubleshootingIn general, when a unit is not operating as expected, the first step in troubleshooting the MicroTech II control system should always be to determine the current operating state and then determine why the unit is currently in that operating state. The current operating state is determined via the unit keypad by viewing the UnitStatus= parameter in the System

menu. Once the current operating state is determined, it then can be assessed whether or not the control is operating cor-rectly in that state and if not why. The following sections dis-cuss various scenarios and some steps for troubleshooting them.

Table 67: Fans Operate After Normal Startup Sequence But:

Problem Check

1. Unit does not leave Fan Only and enter the Econo or Cooling operat-ing state.

1.1. Check Clg Status= parameter in System menu:1. The unit does not enter the Econo operating state unless the Clg Status=

parameter indicates “All Clg” or “Econo.” If it does, refer to Item 1.2 below.

2. The unit does not enter the Cooling operating state unless the Clg Sta-tus= parameter indicates “All Clg” or “Mech Clg.” If it does, refer to Item 1.2 below.

3. The unit does not enter the Econo or the Cooling operating state if the Clg Status= parameter indicates something other than “All Clg”, “Econo” or “Mech Clg.” If this is the case, refer to “Clg Status” on page 45 to determine the reason.

1.2. Compare the Ctrl Temp= parameter to the Eff Clg Spt= parameter in the Zone Cooling menu.1. The unit does not enter the Econo or Cooling operating state unless the

current value of the Ctrl Temp= parameter is above the Eff Clg Spt= by more than half the Clg Deadband= parameter in the Zone Cooling menu. If it is and the unit still does not enter either the Econo or Cooling operat-ing state, MCB is likely defective.

2. If the current value of the Ctrl Temp= parameter is not above the Eff Clg Spt= by more than half the Clg Deadband= parameter in the Zone Cool-ing menu, the Eff Clg Spt= parameter must be adjusted accordingly to enable cooling operation. Refer to “Heat/Cool Changeover” on page 67.

2. Unit does not leave Fan Only and enter Heating operating state.

2.1. Check Htg Status= parameter in System menu:1. The unit does not enter the Heating operating state unless the Htg Sta-

tus= parameter indicates “Htg Ena”. If it does, refer to Item 2.2 below.2. The unit does not enter the Heating operating state if the Htg Status=

parameter indicates anything other than “Htg Ena.” If this is the case, refer to “Htg Status” on page 46 to determine the reason.

2.2. Compare the Ctrl Temp= parameter to the Eff Htg Spt= parameter in the Zone Heating menu.1. The unit does not enter the Heating operating state unless the current

value of the Ctrl Temp= parameter is below the Eff Htg Spt= by more than half the Htg Deadband= parameter in the Zone Heating menu. If it is and the unit is equipped with multi-stage or modulating heat, refer to Item 2.3 below. If it is and the unit still does not enter the Heating operat-ing state, MCB is likely defective.

2. If the Ctrl Temp= is not below the Eff Htg Spt= by more than half the Htg Deadband= parameter in the Zone Heating menu, the Eff Htg Spt= parameter must be adjusted accordingly to enable heating operation. Refer to “Heat/Cool Changeover” on page 67

114 McQuay OM 138-3

Table 68: Unit Does Not Startup and Run at All:

Problem Check

1. Unit does not leave the Off Unoc operat-ing state. (UnitStatus= parameter in the System menu indicates “Off Unoc” and unit does not start.)

1.1. Check Occupancy= parameter in Occupancy menu:1. If the Occupancy = parameter in the Occupancy menu indicates

either “Occ” or “Bypass” and the unit remains in the Off Unoc operating state, MCB is likely defective

2. If the Occupancy = parameter in the Occupancy menu indicates “Unocc” refer to Item 1.2 below.

1.2. Check Occ Mode= parameter in the Occupancy menu:1. If the Occ Mode= parameter is set to “Unocc”, the unit starts only

if unoccupied heating (night setback) or unoccupied cooling (night setup or purge) operation is active. Refer to “Propeller Exhaust Fan Control” on page 95.

2. If the Occ Mode= parameter is set to “Auto”, the unit starts only if at least one of the following are true:a) Field time clock terminals 101 to 102 on TB2 in the main con-

trol box are made (binary input MCB-BI1 is on). Refer to “External Time Scheduling” on page 53.

b) Internal time schedule indicates an occupied period. Refer to “Internal Daily Scheduling” on page 51.

c) Holiday time schedule indicates an occupied period. Refer to “Holiday Scheduling” on page 52.

d) One event schedule indicates an occupied period. Refer to “One Event Scheduling” on page 52.

e) Network time schedule indicates an occupied period. Refer to “Network Time Scheduling” on page 53.

f) Unoccupied heating (night setback) or unoccupied cooling (night setup or purge) operation is active. Refer to “Propeller Exhaust Fan Control” on page 95.

If any one of items a) through f) is true and the Occupancy= parameter in the Occupancy menu still indicates “Unocc” and the unit remains in the “Off Unoc” operating state, MCB is likely defective.

2. Unit does not leave the Off Sw operating state. (UnitStatus= parameter in the Sys-tem menu indicates “Off Sw” and unit does not start.)

2.1. Check terminals 101 and 104 on TB2 in the main control box:1. The unit is disabled and remains in the Off Sw operating state

when terminal 101 is made to 104 on TB2 (binary input MCB-BI2 is on).

2. If terminal 101 is not made to 104 on TB2 (binary input MCB-BI2 is off) and the UnitStatus= parameter continues to indicated “Off Sw”, MCB is likely defective.

McQuay OM 138-3 115

3. Unit does not leave the Off Net operating state. (UnitStatus= parameter in the Sys-tem menu indicates “Off Net” and unit does not start.)

3.1. Check Ctrl Mode= parameter in System menu:1. If the Ctrl Mode= parameter in System menu is set to anything

other than “Auto” and the UnitStatus= parameter in the System menu continues to indicate “Off Net”, refer to Item 3.2.

2. If the Ctrl Mode= parameter in System menu is set to “Auto”, the UnitStatus= parameter indicates “Off Net” when the Appl Mode= parameter in the System menu is set to “Off.” If the Appl Mode= indicates something other than “Off” and the UnitStatus= parame-ter in the System menu continues to indicate “Off Net”, refer to Item 3.2.

3.2. Check Emerg Override= parameter in Occupancy menu:1. The UnitStatus= parameter indicates “Off Net” when the Emerg

Override= parameter is set to “Off.”2. If the Emerg Override= parameter is set to “Norm” and the Unit-

Status= parameter continues to indicate “Off Net”, MCB is likely defective.

4. Unit does not leave the Off Alm operat-ing state. (UnitStatus= parameter in the System menu indicates “Off Alm” and unit does not start.)

4.1. Press the ALARM key on the unit keypad to Check Active Alarm 1 menu:1. If the Active Alarm 1 menu indicates an active “fault”, the alarm

condition must be corrected and the “fault” cleared before unit can be started.

2. If the Active Alarm 1 menu indicates “None” or an alarm type other than a “fault” and the UnitStatus= parameter in the System menu continues to indicate “Off Alm”, MCB is likely defective.

5. Unit does not leave the Off Man operat-ing state. (UnitStatus= parameter in the System menu indicates “Off Man” and unit does not start.)

5.1. Check Ctrl Mode= parameter in System menu:1. If the Ctrl Mode= parameter in System menu is set to “Off”, the

UnitStatus= parameter indicates “Off Man.” The Ctrl Mode= parameter must be set to something other than “Off” before the unit will start.

2. If the Ctrl Mode= parameter in System menu is set to anything other than “Off” and the UnitStatus= parameter in the System menu still indicates “Off Man”, MCB is likely defective.

Table 68: Unit Does Not Startup and Run at All: (Continued)

Problem Check

116 McQuay OM 138-3

Table 69: Unit Does Not Shut Off:

Problem Check

1. Occupancy = parameter in Occupancy menu indicates “Occ” and unit does not shut off.

1.1. Check Terminals 101 to 102 on TB2 in the main control box:1. The Occupancy= parameter in Occupancy menu indicates “Occ”

and the unit runs continuously if the field time clock terminals 101 to 102 on TB2 in the main control box are made (binary input MCB-BI1 is on). If 101 to 102 are not made, refer to Item 1.2.

1.2. Check the Occ Mode= parameter in System menu:1. The Occupancy= parameter in Occupancy menu indicates “Occ”

and the unit runs continuously if the Occ Mode= parameter in Sys-tem menu is set to “Occ”.

2. The Occupancy= parameter in Occupancy menu indicates “Occ” and the unit runs if the Occ Mode= parameter in Occupancy menu is set to “Auto” and any one of the following are true:a) Internal time schedule indicates an occupied period.b) Holiday schedule indicates an occupied period.c) One event schedule indicates an occupied period.d) Network time schedule indicates an occupied period.If none of the items a), b), c) or d) above are true and the Occu-pancy= parameter in Occupancy menu continues to indicate “Occ”, check the OccSrc= parameter is in the Occupancy menu. If this parameter indicates “Int Sched”, refer to item 3 below. If not, the MCB is likely defective.

3. Check the Time=, Day= and Date= parameters in the in the Time/Date menu. Set the current day's time schedule in the Daily Schedule menu to 08:00 - 16:00. Set the Time= parameter to 15:58:00. Let the Time= parameter roll past the 16:00 stop time. The unit should shut off. If it does, set the current day schedule back to the desired value and set the Time= parameter to the correct time. If the unit still does not shut off, the MCB is likely defective.

McQuay OM 138-3 117

2. Occupancy= parameter in Occupancy menu indicates “Unocc” and unit does not shut off.

2.1. Check the UnoccHtg Spt= parameter in the Zone Heating menu:1. If following conditions are all true, the unit starts and runs in the

unoccupied heating mode with the Occupancy= parameter in Occupancy menu indicating “Unocc”:a) The Space Sensor= parameter in the Unit Configuration menu

is set to “Yes.”b) The UnoccHtg Spt= parameter in the Zone Heating menu is

set to a value greater than 0°F.c) The current Space Temp= value is or was below the UnoccHtg

Spt= parameter in the Zone Heating menu and has not risen above the UnoccHtg Spt= by more than the UnoccHtgDiff= parameter in the Zone Heating menu.

If any of the items a), b) or c) above are not true and the unit con-tinues to run while the Occupancy= parameter in Occupancy menu indicates "Unocc", refer to Item 2.2.

2.2. Check the UnoccClg Spt= parameter in the Zone Cooling menu:1. If following conditions are all true, the unit starts and runs in the

unoccupied cooling mode with the Occupancy= parameter in Occupancy menu indicating “Unocc”:a) The Space Sensor= parameter in the Unit Configuration menu

is set to “Yes.”b) The UnoccClg Spt= parameter in the Zone Cooling menu is

set to a value less than 99°F.c) The current Space Temp= value is or was below the UnoccClg

Spt= parameter in the Zone Cooling menu and has not dropped below the UnoccClg Spt= parameter by more than the UnoccClgDiff= parameter in the Zone Cooling menu.

If any of the items a), b) or c) above are not true and the unit con-tinues to run while the Occupancy= parameter in Occupancy menu indicates “Unocc”, MCB is likely defective.

Table 69: Unit Does Not Shut Off: (Continued)

Problem Check

118 McQuay OM 138-3

© 2006 McQuay International • www.mcquay.com • 800-432-1342

McQuay Training and Development

Now that you have made an investment in modern, efficient McQuay equipment, its care should be a high priority. For training information on all McQuay HVAC products, please visit us at www.mcquay.com and click on training, or call 540-248-9646 and ask for the Training Department.

WarrantyAll McQuay equipment is sold pursuant to its standard terms and conditions of sale, including Limited Product Warranty. Consult your local McQuay Representative for warranty details. Refer to Form 933-43285Y. To find your local McQuay Representative, go to www.mcquay.com.

This document contains the most current product information as of this printing. For the most up-to-date product information, please go to www.mcquay.com.

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