Water-Cooled Scroll Compressor Chillers › api › sharepoint › get...driers, liquid line solenoid valves, sight glass/moisture indicators, and thermal expansion valves. Other features

Installation, Operation and Maintenance Manual IOMM WGZ-1

Group: Chiller

Part Number: 330389301

Effective: October 2004

Supercedes: IOMM WGZ

Water-Cooled Scroll Compressor Chillers

WGZ 030AW To WGZ 100AW, Packaged Water-Cooled Chiller

WGZ 030AA To WGZ 100AA, Chiller with Remote Condenser

30 to 100 Tons, 105 to 350 kW R-22, 60 Hz

2 WGZ 030A through 100A IOMM WGZ-1

Table of Contents

Introduction........................................3 General Description .....................................3 Nomenclature ...............................................3 Inspection.....................................................3

Installation..........................................4 Vibration Isolators........................................6

Water Piping.......................................9 Flow Switch ............................................... 11 Glycol Solutions.........................................12 Condenser Water Piping.............................13 Water Pressure Drop ..................................14

Refrigerant Piping ...........................17 Unit with Remote Condenser .....................17 Factory-Mounted Condenser......................20

Dimensional Data.............................21 Physical Data....................................26

AW Water-Cooled ......................................26 AA Remote Condenser...............................28 Operating Limits ........................................29 Components ...............................................29

Wiring ...............................................30 Unit Configuration ..........................31 Electrical Data..................................32

Field Wiring Diagrams...............................39 Control Panel Layout .................................41 Motor Protection Module...........................41

Start-Up and Shutdown...................42 Pre Start-up ................................................42 Start-up.......................................................42 Weekend or Temporary Shutdown .............43

Start-up after Temporary Shutdown............43 Extended Shutdown....................................43 Start-up after Extended Shutdown..............44

Sequence of Operation .................... 45 Standard MicroTech II Controller. 47

General Description....................................47 Setpoints.....................................................50 Equipment Protection (Shutdown) Alarms .51 Limit Alarms...............................................52 Staging Parameters .....................................54 Capacity Overrides .....................................54 Digital Output Control................................55 Analog Output Control ...............................56 Using the Controller ...................................58 Menu Screens .............................................60 Menu Descriptions .....................................61

Optional Controls ............................ 75 Phase/Voltage Monitor (Optional)..............75 Hot Gas Bypass (Optional).........................75

System Maintenance........................ 76 General .......................................................76 Electrical Terminals....................................77 Compressor Lubrication .............................77 Sight glass and Moisture Indicator .............77 Crankcase Heaters ......................................77

Maintenance Schedule .................... 78 System Service ................................. 79

Troubleshooting Chart................................81 Warranty Statement ........................ 82

"McQuay" is a registered trademark of McQuay International 2003 McQuay International

Illustrations and data cover McQuay International products at the time of publication and we reserve the right to make changes in design and construction at anytime without notice.

Our facility is ISO Certified

IOMM WGZ-1 WGZ 030A through 100A 3

Introduction

General Description McQuay Type WGZ water chillers are designed for indoor installations and are available with water-cooled condensers (Model AW), or arranged for use with remote air-cooled or evaporative condensers (Model AA). Each water-cooled unit is completely assembled and factory wired before evacuation, charging and testing. They consist of hermetic scroll compressors, brazed-plate evaporator, water-cooled condenser (WGZ-AW), and complete refrigerant piping.

Units manufactured for use with remote condensers (Models WGZ-AA) have all refrigerant specialties factory-mounted and connection points for refrigerant discharge and liquid lines.

Liquid line components that are included are manual liquid line shutoff valves, charging valves, filter-driers, liquid line solenoid valves, sight glass/moisture indicators, and thermal expansion valves. Other features include compressor crankcase heaters, and a MicroTech II� microprocessor controller.

The electrical control center includes all equipment protection and operating controls necessary for dependable automatic operation.

The compressors are not fused as standard, but can be protected by optional circuit breakers or fuses, or can rely on a field-installed, fused disconnect switch for protection.

Nomenclature

W G Z 100 - A W

Inspection When the equipment is received, all items should be carefully checked against the bill of lading to be sure of a complete shipment. All units must be carefully inspected for damage upon arrival. All shipping damage must be reported to the carrier and a claim must be filed with the carrier. The unit serial plate should be checked before unloading the unit to be sure that it agrees with the power supply available. Physical damage to unit after acceptance is not the responsibility of McQuay.

Note: Unit shipping and operating weights are given in the physical data tables beginning on page 26.

Water-Cooled Condensing

Global

Scroll Compressor

Nominal Capacity (Tons)

W = Water-Cooled Condenser A = Unit Less Condenser

Design Vintage


RemovableLiftingBar

(2) 2”LiftingHoles

Installation

Note: Installation and maintenance are to be performed only by qualified personnel who are familiar with local codes and regulations, and experienced with this type of equipment.

WARNING

Avoid contact with sharp edges. Personal injury can result.

Handling Every model WGZ-AW water chiller with water-cooled condensers is shipped with a full refrigerant charge. For shipment, the charge is contained in the condenser and is isolated by the condenser liquid shutoff valve and the compressor discharge valve common to a pair of compressors.

A holding charge is supplied in remote condenser models, WGZ-AA. The operating charge must be field supplied and charged.

WARNING If the unit has been damaged, allowing the refrigerant to escape, there can be danger

of suffocation in the equipment area since the refrigerant will displace the air. Be sure to review Environmental Protection Agency (EPA) requirements if damage

occurred. Avoid exposing an open flame to the refrigerant.

Moving the Unit Some means such as dollies or skids must be field furnished to protect the unit from accidental damage and to permit easy handling and moving.

Figure 1, Lifting the Unit

It is recommended that all moving and handling be performed with skids or dollies under the unit when possible and that they not be removed until the unit is in the final location.

Never put the weight of the unit against the control box.

In moving, always apply pressure to the base on the skids only and not to the piping or other components. A long bar will help move the unit easily. Avoid dropping the unit at the end of the roll.


If the unit must be hoisted, lift the unit from the removable lifting arms factory-bolted to each end of the unit adjacent to the tube sheet by attaching cables or chains to the end of the arms. A spreader bar must be used to protect the piping, control panel and other areas of the chiller (see Figure 1). The arms should be removed and discarded after use. Do not attach slings to piping or equipment. Do not attempt to lift the unit by lifting points mounted on the compressors. They are for lifting only the compressor should one need to be removed from the unit. Move unit in the upright horizontal position at all times. Set unit down gently when lowering from the truck or rollers.

Table 1, Lifting Loads Package Units (lbs. Less Condenser Units (lbs)

Model L1 L2 L3 L4 Shipping

Weight L1 L2 L3 L4 Shipping Weight

WGZ 030 564 616 655 715 2551 469 502 562 601 2134 WGZ 035 572 626 672 736 2606 473 507 576 617 2172 WGZ 040 584 641 695 764 2684 477 514 592 637 2219 WGZ 045 596 658 717 792 2763 486 525 610 659 2281 WGZ 050 604 668 739 817 2828 487 527 625 676 2315 WGZ 055 646 719 761 846 2973 526 577 643 705 2452 WGZ 060 800 892 855 953 3500 620 673 675 733 2701 WGZ 070 863 966 890 996 3716 673 735 700 764 2871 WGZ 080 900 1009 961 1077 3947 702 769 763 837 3071 WGZ 090 908 1021 1019 1145 4094 700 769 812 892 3172 WGZ 100 916 1031 1059 1191 4197 696 771 841 931 3238

Location WGZ chillers are designed for indoor application and must be located in an area where the surrounding ambient temperature is 40°F (4°C) or above. A good rule of thumb is to place units where ambient temperatures are at least 5°F (3°C) above the leaving water temperature. Because of the electrical control devices, the units should not be exposed to the weather. A plastic cover over the control box is supplied as temporary protection during shipment. A reasonably level and sufficiently strong floor is required for the water chiller. If necessary, additional structural members should be provided to transfer the weight of the unit to the nearest beams.

Note: Unit shipping and operating weights are given in Table 1 and in the physical data tables beginning on page 26.

Space Requirements for Connections and Servicing The chilled water and condenser water (on units with a water-cooled condenser) piping enters and leaves the unit from the right side when looking at the control panel. Left-hand condenser connections are an option. A clearance of at least 3 feet (1219 mm), or more if codes require, should be provided beyond this piping and on all other sides and ends of the unit for general servicing or for changing the compressors, if it ever becomes necessary. On units equipped with a water-cooled condenser (Type WGZ-AW) clearance should also be provided for cleaning or removal of condenser tubes on one end of the unit. The clearance for cleaning depends on the type of apparatus used, but can be as much as the length of the condenser (10 feet, 3050 mm). Tube replacement requires the tube length of 10 feet (3050 mm) plus one to two feet of workspace. This space can often be provided through a doorway or other aperture.

Placing the Unit The small amount of vibration normally encountered with the water chiller makes this unit particularly desirable for basement or ground floor installations where the unit can be mounted directly to the floor. The floor construction should be such that the unit will not affect the building structure, or transmit noise and vibration into the structure.


Control Panel

WaterConnections

4

1

3

2

LB

LF

RB

FRF

Vibration Isolators It is recommended that isolators be used on all upper level installations or in areas where vibration transmission is a consideration.

Figure 2, Isolator Locations Transfer the unit as indicated under “Moving the Unit.” In all cases, set the unit in place and level with a spirit level. When spring-type isolators are required, install springs running under the main unit supports.

The unit should be set initially on shims or blocks at the listed spring free height. When all piping, wiring,

flushing, charging, etc., is completed, the springs are adjusted upward to loosen the blocks or shims that are then removed.

A rubber anti-skid pad should be used under isolators if hold-down bolts are not used.

Installation of spring isolators requires flexible piping connections and at least three feet of flexible electrical conduit to avoid straining the piping and transmitting vibration and noise.

Table 2, Weights & Mountings ARRANGEMENT WGZ-AW, WITH WATER-COOLED CONDENSERS

Corner Weight Lbs (kg) Neoprene-In-Shear Mountings Spring-Flex Mountings Unit Size

Opr. Wt. Lbs. (kg) 1 2 3 4 1 2 3 4 1 2 3 4

030 2692 (1219)

589 (267)

648 (294)

692 (314)

762 (345)

RP-3 Green

RP-3 Green

RP-3 Green

RP-3 Gray

CP-1 Orange

CP-1 Orange

CP-1 Orange

CP-1 Green

035 2760 (1250)

599 (271)

661 (299)

713 (323)

787 (356)

RP-3 Green

RP-3 Green

RP-3 Green

RP-3 Gray

CP-1 Orange

CP-1 Orange

CP-1 Orange

CP-1 Green

040 2866 (1298)

616 (279)

682 (309)

744 (337)

824 (373)

RP-3 Green

RP-3 Green

RP-3 Gray

RP-3 Gray

CP-1 Orange

CP-1 Orange

CP-1 Orange

CP-1 Orange

045 2966 (1344)

632 (286)

702 (318)

773 (350)

860 (389)

RP-3 Green

RP-3 Green

RP-3 Gray

RP-3 Gray

CP-1 Orange

CP-1 Orange

CP-1 Green

CP-1 Green

050 3058 (1385)

644 (292)

718 (325)

802 (363)

894 (405)

RP-3 Green

RP-3 Green

RP-3 Gray

RP-3 Gray

CP-1 Orange

CP-1 Orange

CP-1 Green

CP-1 Green

055 3213 (1455)

688 (312)

772 (350)

826 (374)

927 (420)

RP-3 Gray

RP-3 Gray

RP-3 Gray

RP-3 Gray

CP-1 Orange

CP-1 Gray

CP-1 Gray

CP-1 Gray

060 3809 (1725)

853 (386)

959 (435)

940 (426)

1057 (479)

RP-3 Gray

RP-3 Gray

RP-3 Gray

RP-3 Gray

CP-1 Green

CP-1 Green

CP-1 Gray

CP-1 Gray

070 4025 (1823)

916 (415)

1033 (468)

975 (442)

1100 (498)

RP-3 Gray

RP-3 Gray

RP-3 Gray

RP-4 Black

CP-1 Gray

CP-1 Gray

CP-1 Gray

CP-1 White

080 4289 (1943)

958 (434)

1082 (490)

1056 (478)

1193 (540)

RP-3 Gray

RP-3 Gray

RP-3 Gray

RP-4 Black

CP-1 Gray

CP-1 Gray

CP-1 Gray

CP-1 White

090 4484 (2031)

974 (441)

1103 (500)

1129 (511)

1278 (579)

RP-3 Gray

RP-4 Black

RP-4 Black

RP-4 Black

CP-1 Gray

CP-1 White

CP-1 White

CP-2 Green

100 4627 (2096)

989 (448)

1121 (508)

1179 (534)

1337 (606)

RP-3 Gray

RP-4 Black

RP-4 Black

RP-4 Black

CP-1 Gray

CP-1 White

CP-1 White

CP-2 Green


ARRANGEMENT WGZ-AA, FOR REMOTE CONDENSER

Corner Weight Lbs (kg) Neoprene-In-Shear Mountings Spring-Flex Mountings Unit Size

Opr. Wt. Lbs. (kg) 1 2 3 4 1 2 3 4 1 2 3 4

030 2162 (979)

468 (212)

502 (227)

575 (260)

616 (279)

RP-3 Green

RP-3 Green

RP-3 Green

RP-3 Green

CP-1 Purple

CP-1 Purple

CP-1 Orange

CP-1 Orange

035 2204 (998)

472 (214)

507 (230)

590 (267)

634 (287)

RP-3 Green

RP-3 Green

RP-3 Green

RP-3 Green

CP-1 Purple

CP-1 Purple

CP-1 Orange

CP-1 Orange

040 2257 (1022)

477 (216)

514 (233)

609 (276)

657 (297)

RP-3 Green

RP-3 Green

RP-3 Green

RP-3 Green

CP-1 Purple

CP-1 Purple

CP-1 Orange

CP-1 Orange

045 2329 (1055)

487 (220)

526 (238)

633 (287)

684 (310)

RP-3 Green

RP-3 Green

RP-3 Green

RP-3 Green

CP-1 Purple

CP-1 Purple

CP-1 Orange

CP-1 Orange

050 2370 (1074)

488 (221)

528 (239)

650 (295)

704 (319)

RP-3 Green

RP-3 Green

RP-3 Green

RP-3 Green

CP-1 Purple

CP-1 Purple

CP-1 Orange

CP-1 Orange

055 2505 (1135)

526 (238)

578 (262)

668 (303)

734 (332)

RP-3 Green

RP-3 Green

RP-3 Green

RP-3 Green

CP-1 Purple

CP-1 Purple

CP-1 Orange

CP-1 Orange

060 2771 (1255)

619 (280)

674 (305)

707 (320)

770 (349)

RP-3 Green

RP-3 Green

RP-3 Gray

RP-3 Gray

CP-1 Orange

CP-1 Orange

CP-1 Green

CP-1 Green

070 2942 (1333)

672 (304)

736 (333)

732 (332)

801 (363)

RP-3 Green

RP-3 Green

RP-3 Gray

RP-3 Gray

CP-1 Orange

CP-1 Orange

CP-1 Green

CP-1 Green

080 3154 (1429)

702 (318)

771 (349)

801 (363)

880 (399)

RP-3 Green

RP-3 Gray

RP-3 Gray

RP-3 Gray

CP-1 Orange

CP-1 Green

CP-1 Green

CP-1 Gray

090 3271 (1482)

700 (317)

771 (349)

857 (388)

944 (427)

RP-3 Green

RP-3 Gray

RP-3 Gray

RP-3 Gray

CP-1 Orange

CP-1 Green

CP-1 Green

CP-1 Gray

100 3346 (1516)

697 (316)

773 (350)

890 (403)

987 (447)

RP-3 Green

RP-3 Gray

RP-3 Gray

RP-3 Gray

CP-1 Orange

CP-1 Green

CP-1 Green

CP-1 Gray

Table 3, Spring Flex Isolators Dimensions

In. (mm) Housing Spring Color

Max. Load Each

Lbs. (kg)

Defl. In. (mm)

A B C D E

Housing Part Number

Spring Part Number

CP-1 Red 450 (204)

0.5 (12.7)

7.5 (190.5)

6.0 (152.4)

4.7 (119.4)

2.7 (68.6)

5.5 (139.7) 226102B-00 226115A-00

CP-1 Purple 600 (272)

0.5 (12.7)

7.5 (190.5)

6.0 (152.4)

4.7 (119.4)

2.7 (68.6)

5.5 (139.7) 226102B-00 226116A-00

CP-1 Orange 750 (340)

0.5 (12.7)

7.5 (190.5)

6.0 (152.4)

4.7 (119.4)

2.7 (68.6)

5.5 (139.7) 226102B-00 226117A-00

CP-1 Green 900 (408)

0.5 (12.7)

7.5 (190.5)

6.0 (152.4)

4.7 (119.4)

2.7 (68.6)

5.5 (139.7) 226102B-00 226118A-00

CP-1 Gray 1100 (498)

0.5 (12.7)

7.5 (190.5)

6.0 (152.4)

4.7 (119.4)

2.7 (68.6)

5.5 (139.7) 226102B-00 226119A-00

CP-1 White 1300 (589)

0.5 (12.7)

7.5 (190.5)

6.0 (152.4)

4.7 (119.4)

2.7 (68.6)

5.5 (139.7) 226102B-00 226120A-00

CP-2 Green 1800 (815)

0.5 (12.7)

10.2 (259.1)

9.0 (228.6)

7.7 (195.6)

2.7 (68.6)

5.75 (146.0) 226103B-00 (2) 226118A-00

NOTE: CP-1 housing contains one spring. CP-2 housing contains two identical springs.


Table 4, Neoprene-in-Shear Isolators Dimensions

In. (mm) Type Max. Load

Each Lbs. (kg)

Defl. In. (mm)

A B C D (1) E H L W

McQuay Part Number

RP-3 Green 750 (339)

0.25 (6.4)

2.5 (63.5)

0.5 (12.7)

4.1 (104.1)

0.56 (14.2)

0.25 (6.4)

1.75 (44.4)

5.5 (165)

3.4 (85.7) 216397A-03

RP-3 Gray 1100 (498)

0.25 (6.4)

2.5 (63.5)

0.5 (12.7)

4.1 (104.1)

0.56 (14.2)

0.25 (6.4)

1.75 (44.4)

5.5 (165)

3.4 (85.7) 216397A-05

RP-4 Black 1500 (679)

0.25 (6.4)

3.75 (95.3)

0.5 (12.7)

5.0 (127.0)

0.56 (14.2)

0.25 (6.4)

1.6 (41.1)

6.5 (165.1)

4.6 (116.8) 216398A-04

RP-4 Red 2250 (1019)

0.25 (6.4)

3.75 (95.3)

0.5 (12.7)

5.0 (127.0)

0.56 (14.2)

0.25 (6.4)

1.6 (41.1)

6.5 (165.1)

4.6 (116.8) 216398A-01

Note (1) "D" is the mounting hole diameter.

Figure 3, Spring Flex Mountings Figure 4, Single Neoprene-in-Shear Mounting


Water Piping

General Due to the variety of piping practices, it is advisable to follow the recommendations of local authorities for code compliance. They can supply the installer with the proper building and safety codes required for a safe and proper installation.

Basically, the piping should be designed with a minimum number of bends and changes in elevation to keep system cost down and performance up. Other piping design considerations include:

1. All piping should be installed and supported to prevent the chiller connections from bearing any strain or weight of the system piping.

2. Vibration eliminators to reduce vibration and noise transmission to the building. 3. Shutoff valves to isolate the unit from the piping system during unit servicing. 4. Manual or automatic air vent valves at the high points of the system. Drains should be placed at

the lowest points in the system. 5. Some means of maintaining adequate system water pressure (e.g., expansion tank or regulating

valve). 6. Temperature and pressure indicators located within 3 feet (0.9 meters) of the inlet and outlet of

the vessels to aid in unit servicing. 7. A strainer or some means of removing foreign matter from the water before it enters the pump is

recommended. It should be placed far enough upstream to prevent cavitation at the pump inlet (consult pump manufacturer for recommendations). The use of a strainer will prolong pump life and thus maintain system performance.

Important Note A cleanable 40-mesh strainer must also be placed in the water line just prior to the inlet of the evaporator. This will aid in preventing foreign material from entering and decreasing the performance of the evaporator.

8. If the unit is used as a replacement chiller on a previously existing piping system, the system should be thoroughly flushed prior to unit installation. Regular water analysis and chemical water treatment on the evaporator and condenser is recommended immediately upon equipment start-up.

9. In the event glycol is added to the water system, as an afterthought for freeze protection, recognize that the refrigerant suction pressure will be lower, cooling performance less, and water side pressure drop will be higher. If the percentage of glycol is large, or if propylene glycol is used instead of ethylene glycol, the added pressure drop and loss of performance could be substantial. Reset the freezestat and low leaving water alarm temperatures. The freezestat is factory set to default at 36°F (2.2°C). Reset the freezestat setting to approximately 4° to 5°F (2.3° to 2.8°C) below the leaving chilled water setpoint temperature. See the section titled “Glycol Solutions” for additional information concerning the use of glycol.

10. A preliminary leak check of the water piping should be made before filling the system.

Note: A water flow switch or pressure differential switch must be mounted in the evaporator outlet water line to signal that there is water flow before the unit will start.


Figure 5, Typical Field Evaporator Water Piping Air

Vent

FlowSwitch

VibrationEliminators

Drain

Outlet

Inlet

PIsolationValves

Strainer

NOTE: Water piping must be supported independently from the unit.

System Water Volume It is important to have adequate water volume in the system to provide an opportunity for the chiller to sense a load change, adjust to the change, and then stabilize. As the expected load change becomes more rapid, a greater water volume is needed. The system water volume is the total amount of water in the evaporator, air handling equipment, and associated piping. If the water volume is too low, operational problems can occur including rapid compressor cycling, rapid loading and unloading of compressors, erratic refrigerant flow in the chiller, improper motor cooling, shortened equipment life and other undesirable occurrences.

For normal comfort cooling applications where the cooling load changes relatively slowly, we recommend a minimum system volume of four minutes times the flow rate (GPM). For example, if the design chiller flow rate is 120 gpm, we recommend a minimum system volume of 480 gallons (120 gpm x 4 minutes).

For process applications where the cooling load can change rapidly, additional system water volume is needed. A process example would be the quenching of hot metal objects. The load would be very stable until the hot metal is dipped into the water tank. Then, the load would increase drastically.

Since there are many other factors that can influence performance, systems can successfully operate below these suggestions. However, as the water volume decreases below these guidelines, the possibility of problems increases.

Variable Chilled Water Flow Reducing chilled water flow in proportion to load can reduce total system power consumption. Certain restrictions apply to the amount and rate of flow change. The rate of flow change should be a maximum of 10 percent of the change, per minute. Do not reduce flow lower than the minimum flows listed in the pressure drop data on page 15.

Chilled Water Piping The system water piping must be flushed thoroughly prior to making connections to the unit evaporator. It is required that a 1.0 mm (16 to 20 mesh) strainer be installed in the return water line before the inlet to the chiller. Lay out the water piping so the chilled water circulating pump discharges into the evaporator inlet.

The return water line must be piped to the evaporator inlet connection and the supply water line must be piped to the evaporator outlet connection. If the evaporator water is piped in the reverse direction, a substantial decrease in capacity and efficiency of the unit will be experienced.

A flow switch must be installed in the horizontal piping of the supply (evaporator outlet) water line to prove water flow before starting the unit.


SuctionCircuit #1SuctionCircuit #2

LiquidCircuit #2LiquidCircuit #1

Leaving ChilledWater Sensor

Drain connections should be provided at all low points in the system to permit complete drainage of the system. Air vents should be located at the high points in the system to purge air out of the system. The evaporators are not equipped with vent or drain connections and provision must be made in the entering and leaving chilled water piping for venting and draining.

Pressure gauges should be installed in the inlet and outlet water lines to the evaporator. Pressure drop through the evaporator should be measured to determine water flow from the flow/pressure drop curves on page 15. Vibration eliminators are recommended in both the supply and return water lines.

Chilled water piping should be insulated to reduce heat loss and prevent condensation. Complete unit and system leak tests should be performed prior to insulating the water piping. Insulation with a vapor barrier would be the recommended type of insulation. If the vessel is insulated, the vent and drain connections must extend beyond the proposed insulation thickness for accessibility.

Chillers not run in the winter should have their water systems thoroughly drained if subject to sub-freezing temperatures. If the chiller operates year-round, or if the system is not drained for the winter, the chilled water piping exposed to sub-freezing ambient temperatures should be protected against freezing by wrapping the lines with a heater cable. In addition, an adequate percentage of glycol should be added to the system to further protect the system during low ambient temperature periods. It should be noted that water piping that has been left drained is subject to more corrosion than if filled with water. Use of a Vapor Corrosion Inhibitor (VCI) or some other protection should be considered.

Chilled Water Sensor

Figure 6, Thermostat Well Location

The chilled water sensor is factory installed in the leaving water connection on the evaporator. Care should be taken not to damage the sensor cable or lead wires when working around the unit. It is also advisable to check the lead wire before running the unit to be sure that it is firmly anchored and not rubbing on the frame or any other component. If the sensor is ever removed from the well for servicing, care must be taken to not wipe off the heat-conducting compound supplied in the well.

CAUTION The thermostat bulb should not be exposed to water temperatures above 125°F

(51.7°C) since this will damage it.

Flow Switch A water flow switch must be mounted in the leaving evaporator and condenser water line to prove adequate water flow before the unit can start. This will safeguard against slugging the compressors on start-up. It also serves to shut down the unit in the event that water flow is interrupted to guard against evaporator freeze-up.

A flow switch is available from McQuay under part number 01750330. It is a “paddle” type switch and adaptable to any pipe size from 1 in. (25 mm) to 6 in. (152 mm) nominal. Certain minimum flow rates are required to close the switch and are listed in Table 5. Electrical connections in the unit control center should be made at terminals 33 and 43 (chilled water) and 41 and 53 (condenser water). The normally open contacts of the flow switch should be wired between these two terminals. There is also a set of normally closed contacts on the switch that could be used for an indicator light or an alarm to indicate when a “no flow” condition exists.


1. Apply pipe sealing compound to only the threads of the switch and screw unit into 1 in. (25 mm) reducing tee. The flow arrow must be pointed in the correct direction.

2. Piping should provide a straight length before and after the flow switch of at least five times the pipe diameter without any valves, elbows, or other flow restricting elements.

3. Trim flow switch paddle if needed to fit the pipe diameter. Make sure paddle does not hang up in pipe.

CAUTION

Make sure the arrow on the side of the switch is pointed in the direction of flow. The flow switch is designed to handle the control voltage and should be connected according to the wiring diagram (see wiring diagram inside control box door).

Incorrect installation will cause improper operation and possible evaporator damage.

Table 5, Flow Switch Flow Rates inch 2 2 1/2 3 4 5 6 Pipe Size mm 51 63 76 102 (125) (150) gpm 13.7 17.9 24.2 35.3 48.6 60.3 Flow Lpm 51.8 67.8 91.6 134.0 184.0 228.0 gpm 9.4 12.1 16.4 27.0 37.4 46.8

Minimum Adjustment No

Flow Lpm 35.6 45.8 62.1 102.0 142.0 177.0 gpm 56.4 71.3 89.0 118.0 178.0 245.0 Flow Lpm 214.0 270.0 337.0 446.0 674.0 927.0 gpm 47.4 59.2 72.5 105.0 160.0 225.0

Maximum Adjustment No

Flow Lpm 179.0 224.0 274.0 397.0 606.0 852.0

Glycol Solutions When using a glycol solution, the chiller capacity, flow rate, evaporator pressure drop, and chiller power input can be calculated using the following formulas and reference to Table 6 for ethylene glycol and Table 7 for propylene glycol.

1. Capacity, Capacity is reduced compared to that with plain water. To find the reduced value, multiply the chiller’s capacity when using water by the capacity correction factor C to find the chiller’s capacity when using glycol.

2. Flow, To determine evaporator gpm (or ∆T) knowing ∆T (or gpm) and capacity:

TablesFromGCorrectionFlowxTCapacityGlycolx

GPMGlycol∆

=24

For Metric Applications -- Determine evaporator lps (or ∆T) knowing ∆T (or lps) and kW:

TablesfromGCorrectionFlowxTx

kWLpsGlycol∆

=18.4

3. Pressure Drop, To determine glycol pressure drop through the cooler, enter the water pressure drop graph on page 15 at the actual glycol flow. Multiply the water pressure drop found there by P to obtain corrected glycol pressure drop.

4. Power, To determine glycol system kW, multiply the water system kW by factor K.

Test coolant with a clean, accurate, glycol solution hydrometer (similar to that found in service stations) to determine the freezing point. Obtain percent glycol from the freezing point found in Table 6 or Table 7. On glycol applications the supplier normally recommends that a minimum of 25% solution by weight be used for protection against corrosion or the use of additional inhibitors.


Note: The effect of glycol in the condenser is negligible. As glycol increases in temperature, its characteristics have a tendency to mirror those of water. Therefore, for selection purposes, there is no derate in capacity for glycol in the condenser.

Table 6, Ethylene Glycol Freezing Point Percent

Glycol °F °C C (Capacity) K (Power) G (Flow) P (Pressure

Drop) 10 26 -3 0.991 0.996 1.013 1.070 20 18 -8 0.982 0.992 1.040 1.129 30 7 -14 0.972 0.986 1.074 1.181 40 -7 -22 0.961 0.976 1.121 1.263 50 -28 -33 0.946 0.966 1.178 1.308

Table 7, Propylene Glycol Freezing Point Percent

Glycol °F °C C (Capacity) K (Power) G (Flow) P (Pressure

Drop) 10 26 -3 0.987 0.992 1.010 1.068 20 19 -7 0.975 0.985 1.028 1.147 30 9 -13 0.962 0.978 1.050 1.248 40 -5 -21 0.946 0.971 1.078 1.366 50 -27 -33 0.929 0.965 1.116 1.481

CAUTION

Do not use automotive grade antifreeze. Industrial grade glycols must be used. Automotive antifreeze contains inhibitors which cause plating on copper tubes. The

type and handling of glycol used must be consistent with local codes.

Condenser Water Piping Arrange the condenser water so the water enters the bottom connection of the condenser. The condenser water will discharge from the top connection. Failing to arrange the condenser water as stated above will negatively affect the capacity and efficiency.

Pressure gauges should be installed in the inlet and outlet water lines to the condenser. Pressure drop through the condenser should be measured to determine flow on the pressure drop/flow curves on page 16. Vibration eliminators are recommended in both the supply and return water lines.

Water-cooled condensers can be piped for use with cooling towers, well water, or heat recovery applications. Cooling tower applications should be made with consideration of freeze protection and scaling problems. Contact the cooling tower manufacturer for equipment characteristics and limitations for the specific application.

Head pressure control must be provided if the entering condenser water can fall below 60°F. The WGZ condenser has two refrigerant circuits with a common condenser water circuit. This arrangement makes head pressure control with discharge pressure actuated control valves difficult.

If for some reason the tower water temperature cannot be maintained at a 60°F minimum, or when pond, lake, or well water that can fall below 60°F (15°C) is used as the condensing medium, special discharge pressure control must be used. A water recirculating system with recirculating pump as shown in Figure 7 is recommended. This system also has the advantage of maintaining tube velocity to help prevent tube fouling. The pump should cycle with the chiller.


Circuit #1 Outlet

Condenser

TemperatureControlValve

CondenserWater

Circuit #2 Outlet

Circuit #1 Inlet

Circuit #2 Inlet

Figure 7, Recirculating Discharge Pressure Control System

Water Pressure Drop The vessel flow rates must fall between the minimum and maximum values shown on the appropriate evaporator and condenser curves. Flow rates below the minimum values shown will result in laminar flow that will reduce efficiency, cause erratic operation of the electronic expansion valve and could cause low temperature cutoffs. On the other hand, flow rates exceeding the maximum values shown can cause erosion in the evaporator.

Measure the chilled water pressure drop through the evaporator at field-installed pressure taps. It is important not to include valves or strainers in these readings.


Figure 8, Evaporator Water Pressure Drop, WGZ 030A through 100A

WGZ 030

WGZ 035

WGZ 040WGZ 045

WGZ 050

WGZ 055

WGZ 060

WGZ 070

WGZ 080

WGZ 090

WGZ 100

Minimum Flow Nominal Flow Maximum Flow Flow Rate Pressure Drop Flow Rate Pressure Drop Flow Rate Pressure Drop

WGZ Model

gpm L/s Ft. kPa gpm L/s Ft. kPa gpm L/s Ft. kPa

030 47.0 3.0 1.6 4.8 75.2 4.7 3.9 11.7 125.3 7.9 10.9 32.4 035 51.9 3.3 1.6 4.8 83.1 5.2 3.9 11.7 138.5 8.7 11.1 33.0 040 60.1 3.8 1.8 5.5 96.2 6.1 4.2 12.4 160.4 10.1 12.0 35.8 045 66.9 4.2 1.8 5.5 107.0 6.8 4.2 12.4 178.4 11.3 11.8 35.1 050 73.6 4.6 1.8 5.5 117.8 7.4 4.6 13.8 196.3 12.4 12.0 35.8 055 82.3 5.2 2.1 6.2 131.7 8.3 4.2 12.4 219.5 13.9 11.8 35.1 060 91.0 5.7 2.1 6.2 145.6 9.2 4.2 12.4 242.7 15.3 12.9 38.5 070 104.1 6.6 1.8 5.5 166.6 10.5 4.4 13.1 277.7 17.5 12.2 36.5 080 115.9 7.3 1.8 5.5 185.4 11.7 4.4 13.1 309.1 19.5 12.2 36.5 090 129.2 8.1 1.8 5.5 206.6 13.0 4.2 12.4 344.4 21.7 11.8 35.1 100 142.4 9.0 1.8 5.5 227.8 14.4 4.9 14.5 379.7 24.0 13.4 39.9

Note: Minimum, nominal, and maximum flows are at a 16°F, 10°F, and 6°F chilled water temperature range respectively, and at ARI tons.


Figure 9, Condenser Water Pressure Drop, WGZ 030AW through 100AW

WGZ 030

WGZ 035

WGZ 040

WGZ 045

WGZ 100

WGZ 090

WGZ 080

WGZ 070

WGZ 050

WGZ 055

WGZ 060

Minimum Flow Nominal Flow Maximum Flow Flow Rate Pressure Drop Flow Rate Pressure Drop Flow Rate Pressure Drop

WGZ Model

gpm L/s Ft. kPa gpm L/s Ft. kPa gpm L/s Ft. kPa 030 58.7 3.8 4.2 12.5 94.0 6.0 8.6 25.8 156.6 10.0 20.0 59.9 035 64.9 4.2 4.4 13.1 103.8 6.6 8.9 26.6 173.1 11.1 20.4 61.2 040 75.2 4.8 4.6 13.7 120.3 7.7 9.0 26.9 200.5 12.8 20.2 60.7 045 83.6 5.4 5.0 15.1 133.8 8.6 9.7 29.1 223.0 14.3 21.7 65.0 050 92.0 5.9 5.1 15.3 147.3 9.4 9.5 28.6 245.4 15.7 20.8 62.5 055 102.9 6.6 5.9 17.6 164.6 10.5 10.7 32.0 274.4 17.6 23.1 69.2 060 113.8 7.3 5.0 14.9 182.0 11.6 9.7 29.2 303.3 19.4 21.9 65.9 070 130.2 8.3 5.3 15.8 208.3 13.3 10.0 30.0 347.2 22.2 22.0 66.1 080 144.9 9.3 5.8 17.4 231.8 14.8 10.7 32.1 386.4 24.7 23.2 69.6 090 161.4 10.3 6.2 18.7 258.3 16.5 11.1 33.2 430.5 27.6 23.4 70.2 100 178.0 11.4 5.4 16.1 284.8 18.2 10.1 30.4 474.7 30.4 22.4 67.1


Refrigerant Piping

Unit with Remote Condenser General For remote condenser application (WGZ-AA) such as air-cooled or evaporative condenser, the chillers are shipped with an R-22 holding charge. It is important that the unit be kept tightly closed until the remote condenser is installed, piped to the unit and the high side evacuated.

Refrigerant piping, to and from the unit, should be sized and installed according to the latest ASHRAE Handbook. It is important that the unit piping be properly supported with sound and vibration isolation between tubing and hanger, and that the discharge lines be looped at the condenser and trapped at the compressor to prevent refrigerant and oil from draining into the compressors. Looping the discharge line also provides greater line flexibility.

The discharge gas valves, liquid line solenoids, filter-driers, moisture indicators, and thermostatic expansion valves are all factory mounted as standard equipment with the water chiller.

A liquid line shutoff valve must be added in the field on remote condenser units between the liquid line filter-drier and remote condenser.

After the equipment is properly installed, leak tested, and evacuated, it can be charged with R-22, and run at design load conditions. Add charge until the liquid line sight glass is clear, with no bubbles flowing to the expansion valve. Total operating charge will depend on the air-cooled condenser used and volume of the refrigerant piping.

Note: On the arrangement WGZ-AA units (units with remote condensers), the installer is required to record the refrigerant charge by stamping the total charge and the charge per circuit on the serial plate in the appropriate blocks provided for this purpose.

The following discussion is intended for use as a general guide to the piping of air-cooled condensers.

Discharge lines must be designed to handle oil properly and to protect the compressor from damage that can result from condensing liquid refrigerant in the line during shutdown. Total friction loss for discharge lines of 3 to 6 psi (20.7 to 41.4 kPa) is considered good design. Careful consideration must be given for sizing each section of piping to insure that gas velocities are sufficient at all operating conditions to carry oil. If the velocity in a vertical discharge riser is too low, considerable oil can collect in the riser and the horizontal header, causing the compressor to lose its oil and result in damage due to lack of lubrication. When the compressor load is increased, the oil that had collected during reduced loads can be carried as a slug through the system and back to the compressor, where a sudden increase of oil concentration can cause liquid slugging and damage to the compressor.

Any horizontal run of discharge piping should be pitched away from the compressor approximately 1/8 inch (6.4 mm) per foot (meter) or more. This is necessary to move, by gravity, any oil lying in the header. Oil pockets must be avoided because oil needed in the compressor would collect at such points and the compressor crankcase can become starved.

It is recommended that any discharge lines coming into a horizontal discharge header rise above the centerline of the discharge header. This is necessary to prevent any oil or condensed liquid from draining to the compressor heads when the compressor is not running.


In designing liquid lines, it is important that the liquid reach the expansion valve without flash gas since this gas will reduce the capacity of the valve. Because “flashing” can be caused by a pressure drop in the liquid line, the pressure losses due to friction and changes in static head should be kept to a minimum.

A check valve must be installed in the liquid line in all applications where the ambient temperature can drop below the equipment room temperature. This prevents liquid migration to the condenser, helps maintain a supply of refrigerant in the liquid line for initial start-up, and keeps liquid line pressure high enough on “off” cycle to keep the expansion valve closed.

On systems as described above, a relief valve or relief-type check valve, must be used in the liquid line as shown in piping systems (shown in Figure 11) to relieve dangerous hydraulic pressures that could be created as cool liquid refrigerant in the line between the check valve and the expansion or shutoff valve warms up. A relief device is also recommended in the hot gas piping at the condenser coil as shown in Figure 10 and Figure 11.

Typical Arrangements Figure 10 illustrates a typical piping arrangement involving a remote air-cooled condenser located at a higher elevation than the compressor and receiver. This arrangement is commonly encountered when the air-cooled condenser is on a roof and the compressor and receiver are on grade level or in a basement equipment room.

Notice, in both illustrations, that the hot gas line is looped at the bottom and top of the vertical run. This is done to prevent oil and condensed refrigerant from flowing back into the compressor and causing damage. The highest point in the discharge line should always be above the highest point in the condenser coil. It is advisable to include a purging vent at this point to extract non-condensables from the system.

Figure 11 illustrates another very common application where the air-cooled condenser is located on essentially the same level as the compressor and receiver. The discharge line piping in this case is not too critical. The principal problem encountered with this arrangement is that there is frequently insufficient vertical distance to allow free drainage of liquid refrigerant from the condenser coil to the receiver.

The receiver is used when it is desired to have refrigerant storage capacity, in addition to the pumpdown capability of the condenser.


Condenser

Relief Valve

Check Valve(Preferred)

Purge Valve

Discharge Line

Loop

Receiver

ReceiverBypass

ToEvap.

PreferredSubcoolerHook-up

Relief Valve(Vent to Outdoorsor to Condenser Sideof Liquid LineCheck Valve)

Pitch

Check Valve

Subcooler

Condenser

Relief Valve

Check Valve(Preferred)

Purge Valve

Relief Valve(Vent to Outdoorsor to Condenser Sideof Liquid LineCheck Valve)

Pitch

Check Valve

Discharge Line

Receiver

ReceiverBypass

ToEvap.

PreferredSubcoolerHook-up

Check Valve

Subcooler

Figure 10, Condenser Above Compressor and Receiver

Figure 11, Condenser and Compressor on Same Level


Factory-Mounted Condenser Units with the standard water-cooled, factory-mounted condenser are provided with complete refrigerant piping and full operating refrigerant charge at the factory.

There is a remote possibility on water-cooled units utilizing low temperature pond or river water as a condensing medium, and if the water valves leak, that the condenser and liquid line refrigerant temperature could drop below the equipment room temperature on the “off” cycle. This problem only arises during periods when cold water continues to circulate through the condenser and the unit remains off due to satisfied cooling load.

If this condition occurs:

1. Cycle the condenser pump off with the unit. 2. Check the liquid line solenoid valve for proper operation.

Relief Valve Piping The ANSI/ASHRAE Standard 15, Safety Standard for Refrigeration Systems, specifies that pressure relief valves on vessels containing Group 1 refrigerant (R-22) “shall discharge to the atmosphere at a location not less than 15 feet (4.6 meters) above the adjoining ground level and not less than 20 feet (6.1 meters) from any window, ventilation opening or exit in any building.” The piping must be provided with a rain cap at the outside terminating point and with a drain at the low point on the vent piping to prevent water buildup on the atmospheric side of the relief valve. In addition, a flexible pipe section should be installed in the line to eliminate any piping stress on the relief valve(s).

The size of the discharge pipe from the pressure relief valve should not be less than the size of the pressure relief outlet. When two or more vessels are piped together, the common header and piping to the atmosphere should not be less than the sum of the area of each of the lines connected to the header.

NOTE: Fittings should be provided to permit vent piping to be easily disconnected for inspection or replacement of the relief valve.

Figure 12, Relief Valve Piping


Dimensional Data WGZ-AW Water-Cooled

Figure 13, WGZ 030AW through WGZ 055AW

L

A

121.43085

(4) .875" (22 mm)

Inlet

Outlet

OutletInlet

H

W

Y

1.538

29711

1.538

13.25337

8204

14354

27.8707

52.41331

Z

X

Condenser

Evaporator

12.3311

20508

Control Connection

Evaporator

Power Connections(2) .875" (22 mm)

Mounting Holes

Door Swing Recommendedfor Servicing

38965

36915

4.5114

MicroTech II User Interface

Relief Valves(1) Each End

Maximum Overall Dimensions

in. (mm)

Chiller Water Connection

Victaulic, in. (mm)

Condenser Water Connections

Victaulic, in. (mm)

Center of Gravity in. (mm)

WGZ Model

Number L W H Size A Size X Y Z

030 134.1 (3406)

32 (813)

63.5 (1613)

3” (76)

115.5 (2394)

4” (102)

66 (1676)

27.5 (698)

14.4 (366)

035 134.1 (3406)

32 (813)

63.5 (1613)

3” (76)

116.4 (2957)

4” (102)

66.3 (1684)

27.5 (698)

14.4 (366)

040 134.1 (3406)

32 (813)

63.5 (1613)

3” (76)

117.7 (2991)

4” (102)

66.7 (1694)

27.4 (696)

14.3 (363)

045 134.1 (3406)

32 (813)

63.5 (1613)

3” (76)

119 (3024)

4” (102)

67.1 (1704)

27.6 (701)

14.3 (363)

050 134.1 (3406)

32 (813)

63.5 (1613)

3” (76)

120.4 (3058)

4” (102)

67.5 (1714)

27.4 (696)

14.3 (363)

055 134.1 (3406)

32 (813)

63.5 (1613)

3” (76)

121.1 (3075)

4” (102)

66.4 (1687)

27.5 (698)

14.2 (361)


Figure 14, WGZ-060AW through WGZ-100AW

H

W

9.8248

18458

33.5852

58.11476

121.13075

13.25337

1.538 737

1.538

A

X

Y

Z

(4) .875" (22 mm)

Inlet

Outlet

Outlet

InletCondenser

Diameter Mounting Holes

Evaporator

T

Evaporator

7.7196

L

Control Connection

Power Connections

15382

20508

(2) .875" (22 mm)

Door SwingClearance Recommended

for Servicing

38965

36915

4.5114


Relief Valves(1) Each End


in. (mm)


Victaulic, in. (mm)

Condenser Water Connections

Victaulic, in. (mm)

Center of Gravity in. (mm)

WGZ Model

Number L W H Size A Size T X Y Z

060 144.2 (3663)

32 (813)

66 (1676)

3 (76)

117.2 (2978)

5 (127)

11.0 (280)

64.1 (1628)

31 (787)

13.9 (354)

070 146.7 (3726)

32 (813)

66 (1676)

3 (76)

118.8 (3018) 5 (127) 12.0

(306) 63

(1600) 32

(813) 13.9 (354)

080 146.7 (3726)

32 (813)

66 (1676)

3 (76)

122.5 (3112)

5 (127)

12.0 (306)

62.4 (1585)

32.7 (831)

13.8 (352)

090 149 (3784)

32 (813)

66 (1676)

3 (76)

126.6 (3216)

5 (127)

15.8 (401)

62 (1575)

33.4 (848)

13.8 (352)

100 149 (3784)

32 (813)

66 (1676)

3 (76)

128.9 (3274)

5 (127)

15.8 9401)

66.3 (1684)

33.1 (841)

13.4 (341)


WGZ-AA Remote Condenser Figure 15, Dimensions, WGZ 030AA – WGZ 055AA

121.43085

L A

X

B C D F

"G" Disch. System #2 "G" Disch. System #1

"E" Liquid System #2 "E" Liquid System #1

Inlet

Outlet

Power Connections(2) - .875 (22 mm)

Evaporator

Control Connection

(4) - .875 (22 mm)

13.8350

27.8707

52.41331

24.1613

"G" Disch Conn

12.5318

20508

4.5114

H

Y

"E" Liquid Conn

W

1.538

29737

1.538

Z

Mounting Holes

Door SwingClearance

Recommendedfor Servicing

38965

36915


T

Refrigerant Connections Maximum Overall Dimensions

in. (mm)


Victaulic in. (mm)

System #1 System #2 Connection Size Center of Gravity

in. (mm) WGZ Model

Number

L W H Size A Liquid

F Disch.

C Liquid

D Disch.

B Liquid

E Disch.

G T X Y Z

030 122.4 (3109)

32 (813)

63.5 (1613)

3 (76)

115.5 (2394)

67 (1702)

38.2 (970)

52 (1320)

42.9 (1090)

.875 (22)

1.125 (29)

2.9 (74)

66.7 (1694)

31.2 (792)

14.7 (373)

035 122.4 (3109)

32 (813)

63.5 (1613)

3 (76)

116.4 (2957)

67 (1702)

38.2 (970)

52 (1320)

42.9 (1090)

.875 (22)

1.125 (29)

2.9 (74)

67.3 (1709)

31.3 (795)

14.6 (371)

040 122.4 (3109)

32 (813)

63.5 (1613)

3 (76)

117.7 (2991)

67 (1702)

38.2 (970)

52 (1320)

42.9 (1090)

.875 (22)

1.125 (29)

2.9 (74)

67.9 (1725)

31.5 (800)

14.6 (371)

045 122.4 (3109)

32 (813)

63.5 (1613)

3 (76)

119 (3024)

67 (1702)

38.2 (970)

52 (1320)

42.9 (1090)

.875 (22)

1.125 (29)

2.9 (74)

68.4 (1737)

31.7 (805)

14.6 (371)

050 122.4 (3109)

32 (813)

63.5 (1613)

3 (76)

120.4 (3058)

67 (1702)

38.2 (970)

52 (1320)

42.9 (1090)

.875 (22)

1.125 (29)

2.9 (74)

69.2 (1758)

31.9 (810)

14.5 (368)

055 123.4 (3134)

32 (813)

63.5 (1613)

3 (76)

121.1 (3075)

80.2 (2037)

43.4 (1102)

38.6 (980)

39.5 (1003)

.875 (22)

1.125 (29)

1.125 (29)

1.375 (35)

2.9 (74)

67.8 (1722)

32 (813)

14.5 (368)


Figure 16, Dimensions WGZ 060AA – 080AA

34.2868

85.32166

29.8758

47.51206

121.13075

L

A

X

Inlet

Outlet

Power Connections(2) - .875 (22mm)

(4) - .875 (22mm)Mounting Holes

Evaporator

Control Connection

W

H

Y

15.1382

20508

"G" Disch Conn

"E" Liquid Conn

Z

"G" Disch. System #2 "G" Disch. System #1

"E" Liquid System #1"E" Liquid System #2

Door SwingClearance

38965


36915

19483

30.3770

33.5852

58.11476

1.538

29737

1.538

4.5114


Evaporator

T


in. (mm)

Evaporator Water Connections

Victaulic in. (mm)

Refrigerant Connections (OD)

in. (mm)

Center of Gravity in. (mm) WGZ

MODEL NO.

L W H Size A Liquid

E Discharge

G T X Y Z

060 140 (3556)

32 (813)

66 (1676)

3 (76)

117.2 (2978)

1.125 (29)

1.375 (35)

11 (280)

64.3 (1633)

33.8 (859)

14.2 (362)

070 142.5 (3620)

32 (813)

66 (1676)

3 (76)

118.8 (3018)

1.125 (29)

1.375 (35) 1.625 (41)

12 (306)

63 (1600)

36.6 (930)

14.1 (359)

080 142.5 (3620)

32 (813)

66 (1676)

3 (76)

122.5 (3112)

1.125 (29)

1.625 (41)

12 (306)

64.3 (1633)

38 (965)

14.1 (359)


Figure 17, Dimensions WGZ 090AA – 100AA

H

W

34.5877

59.11501

121.13075

13.25377

1.538

29737

1.538

A

X

Y

Z

(4) .875" (22 mm)

Inlet

Outlet

Diameter Mounting Holes

Evaporator

T

Evaporator

L

38.8986

70.31785

17.7450

29.9760

47.51206

Control Connection

Power Connections

16407

20508

31.2792

"E" Liquid Conn System 2 "E" Liquid Conn System 1

"G" Discharge Conn System 1"G" Discharge Conn System 2

(2) .875" (22 mm)

"E" Liquid Conn

"G" Discharge Conn

Door SwingClearance

38965


36915

4.5114



in. (mm)

Evaporator Water Connections

(Victaulic) in. (mm)

Refrigerant Connections (OD)

Center of Gravity in. (mm) WGZ

MODEL NO.

L W H Size A Liquid

E Discharge

G T X Y Z

090 144.75 (3667)

32 (813)

66 (1676)

3 (76)

126.6 (3216)

1.125 (29)

1.625 (41)

15.8 (401)

63.1 (1603)

38.4 (975)

14.1 (359)

100 144.75 (3667)

32 (813)

66 (1676)

3 (76)

128.9 (3274)

1.125 (29)

1.625 (41)

15.8 (401)

67.5 (1715)

38.6 (980)

13.6 (346)


Physical Data

AW Water-Cooled Table 8, WGZ-030AW - WGZ-055AW

WGZ UNIT SIZE 030 035 040 045 050 055 Unit capacity @ ARI conditions tons, (kW) (1) 31.6 (111.1) 34.9 (122.7) 40.1 (141) 44.2 (155) 48.6 (171) 54.3 (191)

No. Circuits 2 2 2 2 2 2 COMPRESSORS Nominal Horsepower 7.5 9 9 9 10 10 13 10 13 13 13 16 Number (2) 2 2 2 2 2 2 2 2 2 2 2 2 Unloading Steps 27 / 50 / 77 25 / 50 / 75 25 / 50 / 75 28 / 50 / 78 25 / 50 / 75 27 / 50 / 77 Oil Charge per Compressor oz., (l) 140 (4.1) 140 (4.1) 140 (4.1) 140 (4.1) 140 (4.1) 140 (4.1) CONDENSER Number 1 1 1 1 1 1 No. Refrigerant Circuits 2 2 2 2 2 2 Diameter, in., (mm) 10 (254) 10 (254) 10 (254) 10 (254) 10 (254) 10 (254) Tube Length, in., (mm) 120 (3048) 120 (3048) 120 (3048) 120 (3048) 120 (3048) 120 (3048) Design W.P. psig, (kPa): Refrigerant Side 450 (3102) 450 (3102) 450 (3102) 450 (3102) 450 (3102) 450 (3102) Water Side 232 (1599) 232 (1599) 232 (1599) 232 (1599) 232 (1599) 232 (1599) No. of Passes 2 2 2 2 2 2 Pump-Out Capacity, lb., (kg) (3) 279 (126.6) 273 (123.8) 260 (117.9) 253 (114.8) 240 (108.9) 234 (106.1) Connections: Water In & Out, in, (mm) victaulic 4 (102) 4 (102) 4 (102) 4 (102) 4 (102) 4 (102) Relief Valve, Flare In., (mm) ½ (12.7) ½ (12.7) ½ (12.7) ½ (12.7) ½ (12.7) ½ (12.7) Purge Valve, Flare In., (mm) ½ (12.7) ½ (12.7) ½ (12.7) ½ (12.7) ½ (12.7) ½ (12.7) Vent & Drain, in. (mm) FPT ½ (12.7) ½ (12.7) ½ (12.7) ½ (12.7) ½ (12.7) ½ (12.7) Liquid Subcooling Integral Integral Integral Integral Integral Integral EVAPORATOR Number 1 1 1 1 1 1 No. Refrigerant Circuits 2 2 2 2 2 2 Water Volume, gallons, (l) 3.9 (14.7) 4.3 (16.4) 5 (18.9) 5.7 (21.4) 6.3 (23.9) 7.2 (27.3) Refrig. Side D.W.P., psig, (kPa) 450 (3102) 450 (3102) 450 (3102) 450 (3102) 450 (3102) 450 (3102) Water Side D.W.P., psig, (kPa) 363 (2503) 363 (2503) 363 (2503) 363 (2503) 363 (2503) 363 (2503) Water Connections: Inlet & Outlet, in., (mm) victaulic 3 (76) 3 (76) 3 (76) 3 (76) 3 (76) 3 (76) Drain & Vent (NPT INT.) Field Field Field Field Field Field UNIT DIMENSIONS Length In., (mm) 134.1 (3406) 134.1 (3406) 134.1 (3406) 134.1 (3406) 134.1 (3406) 134.1 (3406)Width In., (mm) 32 (813) 32 (813) 32 (813) 32 (813) 32 (813) 32 (813) Height In., (mm) 63.5 (1613) 63.5 (1613) 63.5 (1613) 63.5 (1613) 63.5 (1613) 63.5 (1613) UNIT WEIGHTS Operating Weight, lb., (kg) 2692 (1219) 2760 (1250) 2866 (1298) 2966 (1344) 3058 (1385) 3213 (1455)Shipping Weight, lb., (kg) 2551 (1157) 2606 (1182) 2684 (1217) 2763 (1253) 2828 (1283) 2973 (1349)Operating Charge, lb., (kg) R-22 100 (45.4) 99 (44.9) 94 (42.6) 92 (41.7) 88 (39.9) 89 (40.4)

Notes: 1. Certified in accordance with ARI Standard 550/590-98. 2. All units have two compressors per circuit in parallel. 3. 80% full R-22 at 90°F (32°C) per unit.


Table 9, WGZ-060AW - WGZ-100AW WGZ UNIT SIZE 060 070 080 090 100 Unit capacity @ ARI conditions tons, (kW) (1) 60.3 (212) 68.0 (239) 75.6 (266) 84.4 (297) 93.7 (330)

No. Circuits 2 2 2 2 2 COMPRESSORS Nominal Horsepower 16 16 16 20 20 20 20 25 25 25 Number (2) 2 2 2 2 2 2 2 2 2 2 Unloading Steps 25 / 50 / 75 28 / 50 / 78 25 / 50 / 75 27 / 50 / 77 25 / 50 / 75 Oil Charge, per compressor oz. (l) 140 (4.1) 140 (4.1) 148 (4.3) 148 (4.3) 200 (5.9) 200 (5.9 200 (5.9CONDENSER Number 1 1 1 1 1 No. Refrigerant Circuits 2 2 2 2 2 Diameter, in. (mm) 14 (356) 14 (356) 14 (356) 14 (356) 14 (356) Tube Length, in. (mm) 120 (3048) 120 (3048) 120 (3048) 120 (3048) 120 (3048) Design W.P., psig (kPa): Refrigerant Side 450 (3102) 450 (3102) 450 (3102) 450 (3102) 450 (3102) Water Side 232 (1599) 232 (1599) 232 (1599) 232 (1599) 232 (1599) No. of Passes 2 2 2 2 2 Pump-Out Capacity lb., (kg) (3) 481 (218.2) 462 (209.6) 449 (203.7) 429 (194.6) 409 (185.5)

Connections: Water In & Out, in., (mm) (4) 5 (127) 5 (127) 5 (127) 5 (127) 5 (127) Relief Valve, Flare in., (mm) ½ (12.7) ½ (12.7) ½ (12.7) ½ (12.7) ½ (12.7) Purge Valve, Flare in. (mm) ½ (12.7) ½ (12.7) ½ (12.7) ½ (12.7) ½ (12.7) Vent & Drain, in. (mm) FPT ½ (12.7) ½ (12.7) ½ (12.7) ½ (12.7) ½ (12.7) Liquid Subcooling Integral Integral Integral Integral Integral EVAPORATOR Number 1 1 1 1 1 No. Refrigerant Circuits 2 2 2 2 2 Water Volume, gallons (l) 8.1 (30.7) 9.2 (34.9) 10.8 (40.7) 12.8 (48.3) 13.9 (52.5) Refrigerant Side D.W.P., psig, (kPa)

450 (3102) 450 (3102) 450 (3102) 450 (3102) 450 (3102)

Water Side D.W.P., psig, (kPa) 363 (2503) 363 (2503) 363 (2503) 363 (2503) 363 (2503) Water Connections: In & Out, in. (mm) victaulic 3 (76) 3 (76) 3 (76) 3 (76) 3 (76) Drain & Vent Field Field Field Field Field UNIT DIMENSIONS Length, in. (mm) 144.2 (3663) 146.7 (3726) 146.7 (3726) 149 (3784) 149 (3784) Width, in. (mm) 32 (813) 32 (813) 32 (813) 32 (813) 32 (813) Height, in. (mm) 66 (1676) 66 (1676) 66 (1676) 66 (1676) 66 (1676) UNIT WEIGHTS Operating Weight, lb. (kg) 3809 (1725) 4025 (1823) 4289 (1943) 4484 (2031) 4627 (2096) Shipping Weight, lb. (kg) 3500 (1588) 3716 (1686) 3947 (1790) 4094 (1857) 4197 (1904) R-22 Ref. Charge, lb. (kg) 173 (78.5) 167 (75.7) 163 (73.9) 151 (68.5) 151 (68.5)

Notes: 1. Certified in accordance with ARI Standard 550/590-98. 2. All units have two compressors per circuit in parallel. 3. 80% full R-22 at 90°F (32°C) per unit. 4. Victaulic connections.


AA Remote Condenser Table 10, WGZ-030AA - WGZ-055AA

WGZ UNIT SIZE 030 035 040 045 050 055 Cap @ 44°F LWT , 125°F SDT tons, (kW) 29 (103) 31.6 (112) 36.6 (130) 40.7 (144) 44.7 (158) 49.8 (177)

No. Circuits 2 2 2 2 2 2 COMPRESSORS Nominal Horsepower 7.5 9 9 9 10 10 13 10 13 13 13 16 Number (2) 2 2 2 2 2 2 2 2 2 2 2 2 Unloading Steps 27 / 50 / 77 25 / 50 / 75 25 / 50 / 75 28 / 50 / 78 25 / 50 / 75 27 / 50 / 77 Oil Charge, per compressor oz. (l) 140 (4.1) 140 (4.1) 140 (4.1) 140 (4.1) 140 (4.1) 140 (4.1)

Discharge Valve In., (mm) 1.125 (28) 1.125 (28) 1.125 (28) 1.125 (28) 1.125 (28) 1.125 (28) 1.375 (35)

EVAPORATOR No. Refrigerant Circuits 2 2 2 2 2 2 Water Volume, gallons, (l) 3.9 (14.7) 4.3 (16.4) 5 (18.9) 5.7 (21.4) 6.3 (23.9) 7.2 (27.3) Refrig. Side D.W.P. psig (kPa) 450 (3102) 450 (3102) 450 (3102) 450 (3102) 450 (3102) 450 (3102) Water Side D.W.P. psig (kPa) 363 (2503) 363 (2503) 363 (2503) 363 (2503) 363 (2503) 363 (2503) Water Connections: Inlet & Outlet, in., (mm) (1) 3 (76) 3 (76) 3 (76) 3 (76) 3 (76) 3 (76) Drain & Vent Field Field Field Field Field Field UNIT DIMENSIONS Length In., (mm) 122.4 (3109) 122.4 (3109) 122.4 (3109) 122.4 (3109) 122.4 (3109) 123.4 (3134) Width In., (mm) 32 (813) 32 (813) 32 (813) 32 (813) 32 (813) 32 (813) Height In., (mm) 63.5 (1613) 63.5 (1613) 63.5 (1613) 63.5 (1613) 63.5 (1613) 63.5 (1613) UNIT WEIGHTS Operating Weight, lb. (kg) 2162 (981) 2204 (1000) 2257 (1024) 2329 (1056) 2370 (1075) 2505 (1136) Shipping Weight, lb. (kg) 2134 (968) 2172 (985) 2219 (1007) 2281 (1035) 2315 (1050) 2452 (1112) Holding Charge, lb. (kg) R-22 6.0 (2.7) 6.1 (2.8) 6.4 (2.9) 6.6 (3) 7.0 (3.2) 9.7 (4.4)

Table 11, WGZ-060AA - WGZ-100AA WHR UNIT SIZE 060 070 080 090 100 Cap @ 44°F LWT , 125°F SDT tons, (kW) 54.9 (195) 62.1 (220) 69.5 (246) 77.9 (276) 85.9 (305)

No. Circuits 2 2 2 2 2 COMPRESSORS Nominal Horsepower 16 16 16 20 20 20 20 25 25 25 Number (3) 2 2 2 2 2 2 2 2 2 2 Unloading Steps 25 / 50 / 75 28 / 50 / 78 25 / 50 / 75 27 / 50 / 77 25 / 50 / 75 Oil Charge oz 140 (4.1) 140 (4.1) 148 (4.3) 148 (4.3) 148 (4.3) 148 (4.3) 200 (5.9) 200 (5.9) 200 (5.9)EVAPORATOR No. Refrigerant Circuits 2 2 2 2 2 Water Volume, gallons (l) 8.1 (30.7 9.2 (34.9) 10.8 (40.7) 12.8 (48.3) 13.9 (52.5) Refrigerant Side D.W.P., psig (kPa)

450 (3102) 450 (3102) 450 (3102) 450 (3102) 450 (3102)

Water Side D.W.P., psig (kPa) 363 (2503) 363 (2503) 363 (2503) 363 (2503) 363 (2503)

Water Connections: Inlet & Outlet, in. (mm) (1) 3 (76) 3 (76) 3 (76) 3 (76) 3 (76) Drain & Vent Field Field Field Field Field UNIT DIMENSIONS Length, in. (mm) 140 (3556) 142.5 (3620) 142.5 (3620) 144.75 (3677) 144.75 (3677) Width, in. (mm) 32 (813) 32 (813) 32 (813) 32 (813) 32 (813) Height, in. (mm) 66 (1676) 66 (1676) 66 (1676) 66 (1676) 66 (1676) UNIT WEIGHTS Operating Weight, lb. (kg) 2771 (1257) 2942 (1334) 3154 (1431) 3271 (1484) 3346 (1518) Shipping Weight, lb. (kg) 2701 (1225) 2871 (1302) 3071 (1393) 3172 (1439) 3238 (1469) Holding Charge, lb. (kg) R-22 10.0 (4.5) 10.5 (4.7) 11.1 (5) 11.8 (5.4) 12.3 (5.6) Notes:

1. Victaulic connections. 2. All units have two compressors per circuit in parallel.


Operating Limits • Maximum allowable condenser water pressure is 232 psig (1599 kPa). • Maximum allowable cooler water pressure is 363 psig (2509 kPa). • Maximum design saturated discharge temperature is 140°F (60°C). • Maximum allowable water temperature to cooler in a non-operating cycle is 100°F (37.8°C).

Maximum entering water temperature for operating cycle is 90°F (32.2°C) (during system changeover from heating to cooling cycle).

• Minimum leaving water temperature from the cooler without freeze protection is 40°F (4.4°C). • Minimum entering tower condenser water temperature is 60°F (15.6°C).

Components Figure 18, Compressor Locations

4 2 3 1

Circuit 2 Circuit 1 Control Panel

EvaporatorEvaporator andCondenserConnections

Table 12, Major Components System #1 System #2 Expansion Valve Unit

Size Comp. #1 Comp. #3 Comp. #2 Comp. #4

Evap. Vessel

Size

Cond. Vessel

Size System #1 System #2

030 ZR90K3 ZR90K3 ZR11M3 ZR11M3 AC250-70DQ C1007-068 OVE-20-CP100 OVE-20-CP100035 ZR11M3 ZR11M3 ZR11M3 ZR11M3 AC250-78DQ C1007-076 OVE-20-CP100 OVE-20-CP100040 ZR12M3 ZR12M3 ZR12M3 ZR12M3 AC250-90DQ C1007-084 OVE-20-CP100 OVE-20-CP100045 ZR12M3 ZR12M3 ZR16M3 ZR16M3 AC250-102DQ C1207-092 OVE-30-CP100 OVE-30-CP100050 ZR16M3 ZR16M3 ZR16M3 ZR16M3 AC250-114DQ C1207-108 OVE-30-CP100 OVE-30-CP100055 ZR16M3 ZR16M3 ZR19M3 ZR19M3 AC250-130DQ C1407-120 OVE-30-CP100 Y929-VCP100 060 ZR19M3 ZR19M3 ZR19M3 ZR19M3 AC250-146DQ C1607-136 Y929-VCP100 Y929-VCP100 070 ZR19M3 ZR19M3 ZR250KC ZR250KC AC250-166DQ C1010-092 Y929-VCP100 Y929-VCP100 080 ZR250KC ZR250KC ZR250KC ZR250KC AC250-194DQ C1210-104 Y929-VCP100 Y929-VCP100 090 ZR250KC ZR250KC ZR300KC ZR300KC AC250-230DQ C1210-112 OVE-55-CP100 OVE-55-CP100100 ZR300KC ZR300KC ZR300KC ZR300KC AC250-250DQ C1210-128 OVE-55-CP100 OVE-55-CP100


Wiring

Field Wiring, Power The WGZ “A” vintage chillers are built standard with compressor contractors and power terminal block, designed for single power supply to the unit. Optional power connections include a non-fused disconnect switch mounted in the control box or multi-point power connection.

A factory installed control circuit transformer is standard. Optionally, a field-installed control power source can be wired to the unit.

Circuit breakers for backup compressor short circuit protection are standard on all units.

Wiring and conduit selections must comply with the National Electrical Code and/or local requirements.

An open fuse indicates a short, ground, or overload. Before replacing a fuse or restarting a compressor, the trouble must be found and corrected. Tables in the Electrical Data section (page 32) give specific information on recommended wire sizes.

Unit power inlet wiring must enter the control box (right side) through a patch plate provided for field terminating conduit. (Refer to control panel dimension drawings for general location of power inlet and components.)

NOTE: Use only copper conductors in main terminal block. Terminations are sized for copper only.

Field Wiring, Control A factory-mounted control transformer is provided to supply the correct control circuit voltage.

The transformer power leads are connected to the power block PB1 or disconnect switch DS1.

Interlock Wiring, Condenser Pump Starter or Air Cooled Condenser Fan Starter Provisions are made for interlocking a condenser pump starter, tower fans, a tower bypass valve, or up to eight air-cooled condenser fan contactors to be controlled by the MicroTech II unit controller. Condenser fan operation can also be controlled by pressure switches supplied with the condenser. Coil voltage must be 115 volts with a maximum of 20 VA.

An evaporator and condenser (water-cooled units only) flow switch is necessary on all units. It is also advisable to wire a chilled water pump interlock in series with the flow switch for additional freeze protection.

Ambient Air Sensor Units with a remote air-cooled condenser will have an outdoor air sensor furnished with the unit, inside the control panel and wired to the correct terminals. It must be installed outdoors in a location that will give the true outdoor temperature that the condenser coils will see. Splicing of the sensor lead may be required. The sensor must be installed for the unit to operate.


Unit Configuration

The chiller unit has two refrigerant circuits, two tandem scroll compressors (total of four), a single two-circuited brazed plate evaporator, a single two-circuited water-cooled condenser, interconnecting refrigerant piping and a control panel with associated sensors and transducers.

Figure 19, Schematic Piping Diagram (One of Two Circuits)

Comp#2

Comp#1

Condenser CondenserWater

EvaporatorChilledWater

S

F-D

T

S S

CV

SP

P1

LWT

T

T

Legend:

Temperature Sensor

Pressure Transducer

Pressure (High Pressure Cutout)

Temperataure Sensor, LeavingChilled Water Control

TT

TP

P1

LWT

Relief Valve

Schrader Fitting

Thermal Expansion Valve

Sight Glass / Moisture Indicator

Charging Valve

TS

CV

SSolenoid Valve

F-D Filter-Drier

Angle Valve

Ball Valve


Electrical Data

Table 13, Compressor Amp Draw, WGZ 030 - WGZ 100 Rated Load Amps (1) Locked Rotor Amps (2)

Per compressor (2 / circuit)

Across-The-Line Start

WGZ Unit Size

Voltage 3-Phase

Freq (Hz)

Circuit 1 Circuit 2 Circuit 1 Circuit 2 208 23.7 29.9 189 232 230 23.7 29.9 189 232 460 12.5 15.3 99 125

030

575

60

9.1 11.6 74 100 208 29.9 29.9 232 232 230 29.9 29.9 232 232 460 15.3 15.3 125 125

035

575

60

11.6 11.6 100 100 208 33.6 33.6 255 255 230 33.6 33.6 255 255 460 16.5 16.5 127 127

040

575

60

13.7 13.7 100 100 208 33.6 41.0 255 350 230 33.6 41.0 255 350 460 16.5 21.8 127 158

045

575

60

13.7 17.3 100 125 208 41.0 41.0 350 350 230 41.0 41.0 350 350 460 21.8 21.8 158 158

050

575

60

17.3 17.3 125 125 208 41.0 52.6 350 425 230 41.0 52.6 350 425 460 21.8 23.7 158 187

055

575

60

17.3 21.7 125 148 208 52.6 52.6 425 425 230 52.6 52.6 425 425 460 23.7 23.7 187 187

060

575

60

21.7 21.7 148 148 208 52.6 70.0 425 448 230 52.6 70.0 425 448 460 23.7 35.0 187 225

070

575

60

21.7 28.0 148 180 208 70.0 70.0 448 448 230 70.0 70.0 448 448 460 35.0 35.0 225 225

080

575

60

28.0 28.0 180 180 208 70.0 79.0 448 500 230 70.0 79.0 448 500 460 35.0 38.5 225 250

090

575

60

28.0 29.0 180 198 208 79.0 79.0 500 500 230 79.0 79.0 500 500 460 38.5 38.5 250 250

100

575

60

29.0 29.0 198 198 NOTE: 1. Compressor RLA values are for wire sizing purposes only and do not reflect normal operating current draw.


Table 14, Wire Sizing Amps, WGZ 030 - WGZ 100

Minimum Circuit Ampacity (MCA) (1)

Multiple Point Power Supply(3)

WGZ Unit Size

Voltage 3-Phase

Freq. (Hz) Single Point

Power Supply(2) Circuit 1 Circuit 2

208 115 54 68 230 115 54 68 460 60 29 35

030

575

60

45 21 27 208 128 68 68 230 128 68 68 460 66 35 35

035

575

60

50 27 27 208 143 76 76 230 143 76 76 460 71 38 38

040

575

60

59 31 31 208 160 76 93 230 160 76 93 460 83 38 50

045

575

60

67 31 39 208 175 93 93 230 175 93 93 460 93 50 50

050

575

60

74 39 39 208 201 93 119 230 201 93 119 460 97 50 54

055

575

60

84 39 49 208 224 119 119 230 224 119 119 460 101 54 54

060

575

60

93 49 49 208 263 119 158 230 263 119 158 460 127 54 79

070

575

60

104 49 63 208 298 158 158 230 298 158 158 460 149 79 79

080

575

60

119 63 63 208 318 158 178 230 318 158 178 460 157 79 87

090

575

60

122 63 66 208 336 178 178 230 336 178 178 460 164 87 87

100

575

60

124 66 66

NOTES: 1. Unit wire sizing amps are equal to 125% of the largest compressor-motor RLA, plus 100% of RLA of all other loads in the

circuit including control transformer. 2. Single point power supply requires a single fused disconnect to supply electrical power to the unit. 3. Multiple point power supply requires two independent power circuits with separate fused disconnects. (Two compressor

circuits and control circuit will be wired to Circuit #1 from the factory).


Table 15, Fuse Sizing, WGZ 030 - WGZ 100 Recommended Fuse Size(1) Maximum Fuse Size(2)

Single Point Multiple Point Single Point Multiple Point WGZ Unit Size

Voltage 3-Phase

Freq. (Hz)

Total Unit Circuit #1 Circuit #2 Total Unit Circuit #1 Circuit #2 208 125 60 80 125 70 90 230 125 60 80 125 70 90 460 70 35 40 70 40 45

030

575

60

50 25 30 50 25 35 208 150 80 80 150 90 90 230 150 80 80 150 90 90 460 70 40 40 80 45 45

035

575

60

60 30 30 60 35 35 208 175 90 90 175 100 100 230 175 90 90 175 100 100 460 80 45 45 80 50 50

040

575

60

70 45 45 70 40 40 208 175 90 110 200 100 125 230 175 90 110 200 100 125 460 90 45 60 100 50 70 045

575

60

80 45 50 80 40 50 208 200 110 110 200 125 125 230 200 110 110 200 125 125 460 100 60 60 110 70 70

050

575

60

80 50 50 90 50 50 208 225 110 150 250 125 150 230 225 110 150 250 125 150 460 110 60 60 110 70 70

055

575

60

90 50 60 100 50 70 208 250 150 150 250 150 150 230 250 150 150 250 150 150 460 110 60 60 110 70 70

060

575

60

100 60 60 100 70 70 208 300 150 200 300 150 225 230 300 150 200 300 150 225 460 150 60 100 150 70 110

070

575

60

125 60 80 125 70 90 208 350 200 200 350 225 225 230 350 200 200 350 225 225 460 175 100 100 175 110 110

080

575

60

125 80 80 125 90 90 208 350 200 225 350 225 250 230 350 200 225 350 225 250 460 175 100 110 175 110 125

090

575

60

150 80 80 150 90 90 208 400 225 225 400 250 250 230 400 225 225 400 250 250 460 200 110 110 200 125 125

100

575

60

150 80 80 150 90 90

NOTES: 1. "Recommended Fuse Size" is selected at approximately 150% of the largest compressor RLA, plus 100% of all other circuit load. 2. "Maximum Fuse Size" is selected at approximately 225% of the largest compressor RLA, plus 100% of all other loads.


Table 16, Wire Sizing, WGZ 030 - WGZ 100 Single Point Multiple Point

Unit Circuit #1 Circuit #2 WGZ Unit Size

Voltage 3-Phase

Freq. (Hz)

Number Wire Size Number Wire Size Number Wire Size 208 3 1 GA 3 6 GA 3 4 GA 230 3 1 GA 3 6 GA 3 4 GA 460 3 6 GA 3 10 GA 3 8 GA

030

575

60

3 8 GA 3 10 GA 3 8 GA 208 3 1/0 3 4 GA 3 4 GA 230 3 1/0 3 4 GA 3 4 GA 460 3 4 GA 3 8 GA 3 8 GA

035

575

60


040

575

60


045

575

60


050

575

60


055

575

60


060

575

60

3 3 GA 3 8 GA 3 8 GA 208 3 300 kcmil 3 1 GA 3 2/0 230 3 300 kcmil 3 1 GA 3 2/0 460 3 1 GA 3 6 GA 3 4 GA

070

575

60

3 2 GA 3 8 GA 3 6 GA 208 3 350 kcmil 3 2/0 3 2/0 230 3 350 kcmil 3 2/0 3 2/0 460 3 1/0 3 4 GA 3 4 GA

080

575

60


090

575

60


100

575

60

3 1 GA 3 4 GA 3 4 GA


Table 17, Single Point Connection Sizing, WGZ 030 - WGZ 100 Single Point

Power Block Disconnect Switch WGZ Unit Size

Voltage 3-Phase

Freq. (Hz)

Size (1) Connection (3) Size (2) Connection (3)

208 175 14 GA – 2/0 200 6GA – 300 kcmil 230 175 14 GA – 2/0 200 6GA – 300 kcmil 460 175 14 GA – 2/0 175 6GA – 300 kcmil

030

575

60

175 14 GA – 2/0 175 6GA – 300 kcmil


035

575

60

175 14 GA – 2/0 175 6GA – 300 kcmil


040

575

60

175 14 GA – 2/0 175 6GA – 300 kcmil

208 335 6 GA – 400 kcmil 400 2GA – 600 kcmil 230 335 6 GA – 400 kcmil 400 2GA – 600 kcmil 460 175 14 GA – 2/0 200 6GA – 300 kcmil

045

575

60

175 14 GA – 2/0 175 6GA – 300 kcmil


050

575

60

175 14 GA – 2/0 175 6GA – 300 kcmil

208 335 6 GA – 400 kcmil 400 2GA – 600 kcmil 230 335 6 GA – 400 kcmil 400 2GA – 600 kcmil 460

60

175 14 GA – 2/0 200 6GA – 300 kcmil 055

575 175 14 GA – 2/0 200 6GA – 300 kcmil


060

575

60

175 14 GA – 2/0 200 6GA – 300 kcmil

208 335 6 GA – 400 kcmil 600 (2) 2GA – 600 kcmil 230 335 6 GA – 400 kcmil 600 (2) 2GA – 600 kcmil 460 175 14 GA – 2/0 200 6GA – 300 kcmil

070

575

60

175 14 GA – 2/0 200 6GA – 300 kcmil

208 760 2 GA – 500 kcmil 600 (2) 2GA – 600 kcmil 230 760 2 GA – 500 kcmil 600 (2) 2GA – 600 kcmil 460 335 6 GA – 400 kcmil 200 6GA – 300 kcmil

080

575

60

335 6 GA – 400 kcmil 200 6GA – 300 kcmil


090

575

60

335 6 GA – 400 kcmil 200 6GA – 300 kcmil


100

575

60

335 6 GA – 400 kcmil 200 6GA – 300 kcmil NOTES: 1. "Size" is the maximum amperage rating for the terminals or the main electrical device. 2. "Size" is the disconnect part number and not the amperage rating for the terminals or the main electrical device. 3. "Connection" is the range of wire sizes that the terminals on the electrical device will accept.


Table 18, Multiple Point Connection Sizing, WGZ 030 - WGZ 100 Multiple Point – Circuit #1 Multiple Point – Circuit #2

Power Block Disconnect Switch Power Block Disconnect Switch WGZ Unit Size

Voltage 3-Phase

Freq. (Hz)

Size (1) Connection (3) Size (2) Connection (3) Size (1) Connection (3) Size (2) Connection (3)

208 175 14 GA – 2/0 100 8 GA – 2/0 175 14 GA – 2/0 100 8 GA – 2/0 230 175 14 GA – 2/0 100 8 GA – 2/0 175 14 GA – 2/0 100 8 GA – 2/0 460 175 14 GA – 2/0 45 14 GA – 4 GA 175 14 GA – 2/0 45 14 GA – 4 GA

030

575

60

175 14 GA – 2/0 32 18 GA – 8 GA 175 14 GA – 2/0 32 18 GA – 8 GA


035

575

60

175 14 GA – 2/0 45 14 GA – 4 GA 175 14 GA – 2/0 45 14 GA – 4 GA


040

575

60

175 14 GA – 2/0 45 14 GA – 4 GA 175 14 GA – 2/0 45 14 GA – 4 GA

208 175 14 GA – 2/0 160 8 GA – 2/0 175 14 GA – 2/0 200 6GA – 300 kcmil230 175 14 GA – 2/0 160 8 GA – 2/0 175 14 GA – 2/0 175 6GA – 300 kcmil460 175 14 GA – 2/0 45 14 GA – 4 GA 175 14 GA – 2/0 45 14 GA – 4 GA

045

575

60

175 14 GA – 2/0 63 14 GA – 1 GA 175 14 GA – 2/0 63 14 GA – 1 GA

208 175 14 GA – 2/0 200 6GA – 300 kcmil 175 14 GA – 2/0 200 6GA – 300 kcmil230 175 14 GA – 2/0 175 6GA – 300 kcmil 175 14 GA – 2/0 175 6GA – 300 kcmil460 175 14 GA – 2/0 100 8 GA – 2/0 175 14 GA – 2/0 100 8 GA – 2/0

050

575

60

175 14 GA – 2/0 63 14 GA – 1 GA 175 14 GA – 2/0 63 14 GA – 1 GA


055

575

60

175 14 GA – 2/0 160 8 GA – 2/0 175 14 GA – 2/0 160 8 GA – 2/0


060

575

60

175 14 GA – 2/0 160 8 GA – 2/0 175 14 GA – 2/0 160 8 GA – 2/0

208 175 14 GA – 2/0 200 6GA – 300 kcmil 335 6 GA – 400 kcmil 400 2GA – 600 kcmil230 175 14 GA – 2/0 200 6GA – 300 kcmil 335 6 GA – 400 kcmil 200 6GA – 300 kcmil460 175 14 GA – 2/0 100 8 GA – 2/0 175 14 GA – 2/0 175 6GA – 300 kcmil

070

575

60

175 14 GA – 2/0 160 8 GA – 2/0 175 14 GA – 2/0 160 8 GA – 2/0

208 335 6 GA – 400 kcmil 400 2GA – 600 kcmil 335 6 GA – 400 kcmil 400 2GA – 600 kcmil230 335 6 GA – 400 kcmil 200 6GA – 300 kcmil 335 6 GA – 400 kcmil 200 6GA – 300 kcmil460 175 14 GA – 2/0 175 6GA – 300 kcmil 175 14 GA – 2/0 175 6GA – 300 kcmil

080

575

60

175 14 GA – 2/0 160 8 GA – 2/0 175 14 GA – 2/0 160 8 GA – 2/0


090

575

60

175 14 GA – 2/0 160 8 GA – 2/0 175 14 GA – 2/0 160 8 GA – 2/0


100

575

60

175 14 GA – 2/0 160 8 GA – 2/0 175 14 GA – 2/0 160 8 GA – 2/0 NOTES: 1. "Size" is the maximum amperage rating for the terminals or the main electrical device. 2. "Size" is the disconnect part number and not the amperage rating for the terminals or the main electrical device. 3. "Connection" is the range of wire sizes that the terminals on the electrical device will accept.


Notes for “Electrical Data Single Point” Power: 1. Wire sizing amps is 10 amps if a separate 115V power supply is used. 2. Recommended power lead wire sizes for 3 conductors per conduit are based on 100% conductor

ampacity in accordance with NEC. Voltage drop has not been included. Therefore, it is recommended that power leads be kept short. All terminal block connections must be made with copper (type THW) wire.

3. The recommended power lead wire sizes are based on an ambient temperature of 86°F (30°C). Ampacity correction factors must be applied for other ambient temperatures. Refer to the National Electrical Code Handbook.

4. Must be electrically grounded according to national and local electrical codes.

Power Limitations: 1. Voltage within ± 10 percent of nameplate rating. 2. Phase unbalance not to exceed 3%.

Notes for “Field Wiring Data” 1. Requires a single disconnect to supply electrical power to the unit. This power supply must

either be fused or use an HACR type circuit breaker. 2. All field wiring to unit power block or optional non-fused disconnect switch must be copper. 3. All field wire size values given in table apply to 75°C rated wire per NEC.


Field Wiring Diagrams Figure 20, WGZ 030AW – 100AW Field Wiring Diagram

UNIT MAINTERMINAL BLOCK

DISCONNECT (BY OTHERS)

3 PHASEPOWER

SUPPLY

GND LUG

TO COMPRESSOR(S)

FUSED CONTROLCIRCUIT

TRANSFORMER

10AFUSE

NTB1

1(BY OTHERS)


11

14

120VACCONTROL POWER

10

15

FACTORY SUPPLIED ALARMFIELD WIRED

ALARM BELLOPTION

120VAC

2

CONTROLCIRCUITFUSE

120 VAC

TB1-20

ALARM BELL RELAY

GND

CDW PUMP RELAY J15-N08

CHW PUMP RELAY(BY OTHERS)

120 VAC 1.0 AMP MAX

N

N

120 VAC

120 VAC

(BY OTHERS)120 VAC 1.0 AMP MAX

J16-N09N

120 VAC


J16-N10120 VAC


TOWER FAN #1 COIL

TOWER FAN #2 COIL

TB2

40

53

897IF REMOTE STOP CONTROL IS USED, REMOVE LEAD 897

42

55

AUTOOFF

MANUAL

ON(BY OTHERS) 900

IF ICE MODE IS USED REMOVE LEAD FROM TERM 42 TO 55.

FROM TERM 40 TO 53.

ICE MODE SWITCH

GND

38

50

51

4-20 MA FOR

(BY OTHERS)DEMAND LIMIT

AUTOOFF

MANUAL

ON

TIMECLOCK

(BY OTHERS)REMOTE STOP SWITCH

NOR. OPEN PUMP AUX.

CONTACTS (OPTIONAL) 41

53(BY OTHERS)

CDW FLOW SWITCH--MANDATORY--

NOR. OPEN PUMP AUX.

CONTACTS (OPTIONAL) 33

43(BY OTHERS)

CHW FLOW SWITCH--MANDATORY--

4-20 MA FORCHW RESET

(BY OTHERS)

GND

38

48

49

1

2

3

*

J11

COMMUNICATIONPORT

Rx-/Tx-

Rx+/Tx+

GND

CONTROLLER

TB1-12

TB1-12

CONTROLLER

330258901-R4

FIELD SUPPLIED

OPTION


Figure 21, WGZ 030AA – 100AA Field Wiring Diagram (Remote Condenser)

UNIT MAINTERMINAL BLOCK


3 PHASEPOWERSUPPLY

GND LUG

TO COMPRESSOR(S)

FUSED CONTROLCIRCUIT

TRANSFORMER

10AFUSE

NTB1

1(BY OTHERS)


11

14

120VACCONTROL POWER

2

CONTROLCIRCUIT

FUSE

120 VAC

TB1-20

CHW PUMP RELAY(BY OTHERS)

120 VAC 1.0 AMP MAX

N

120 VAC

330259001-R4

10

15

FACTORY SUPPLIED ALARMFIELD WIRED

ALARM BELLOPTION

120VACALARM BELL RELAY

GNDTB2

40

53

897IF REMOTE STOP CONTROL IS USED, REMOVE LEAD 897

42

55

AUTOOFF

MANUAL

ON(BY OTHERS) 900

IF ICE MODE IS USED REMOVE LEAD FROM TERM 42 TO 55.

FROM TERM 40 TO 53.

ICE MODE SWITCH

GND

38

50

51

4-20 MA FOR

(BY OTHERS)DEMAND LIMIT

AUTOOFF

MANUAL

ON

TIMECLOCK

(BY OTHERS)REMOTE STOP SWITCH

NOR. OPEN PUMP AUX.CONTACTS (OPTIONAL)

33

43

(BY OTHERS)CHW FLOW SWITCH --MANDATORY--

4-20 MA FORCHW RESET(BY OTHERS)

GND

38

48

49

1

2

3

*

J11

COMMUNICATIONPORT

Rx-/Tx-

Rx+/Tx+

GND

TB3

65

N

24 VAC AMP MAX

24 VAC

65

N

24 VAC AMP MAX

24 VAC

70

N

24 VAC AMP MAX

24 VAC

LIQUID LINE #1 SOLENOID

LIQUID LINE #2 SOLENOID

62

63

J15-N08N

J16-N09

HOT GAS BYPASS #1 SOLENOID

67

120 VAC

FAN MOTOR #1 COIL

(BY OTHERS)

J16-N010

(BY OTHERS)

J16-N011

(BY OTHERS)

FAN MOTOR #2 COIL


120 VAC 1.0 AMP MAX

120 VAC 1.0 AMP MAX

120 VAC

120 VAC

120 VAC

FAN MOTOR #3 COIL

J18-N013120 VAC120 VAC 1.0 AMP MAX

FAN MOTOR #4 COIL

(BY OTHERS)

J22-N016

(BY OTHERS)

J22-N017

(BY OTHERS)

J22-N018

120 VAC

120 VAC

120 VAC

120 VAC 1.0 AMP MAX

120 VAC 1.0 AMP MAX

120 VAC 1.0 AMP MAX

FAN MOTOR #5 COIL

FAN MOTOR #6 COIL

FAN MOTOR #7 COIL

FAN MOTOR #8 COIL (BY OTHERS)120 VAC 1.0 AMP MAX

CONTROLLER

CONTROLLER

TB1-12

N

OPTIONAL

24 VAC AMP MAX

24 VAC

HOT GAS BYPASS #2 SOLENOID

68

70

FIELDSUPPLIED

OPTION

NOTE:CONDENSER FAN MOTORSCAN ALSO BE CONTROLLEDBY PRESSURE SWITCHESON THE CONDENSER.


Control Panel Layout Figure 22, Typical Control Panel

NOTES:

1. Additional space provided in the upper right section for extra components required for optional multiple point power connection and optional circuit breakers.

2. Front door has opening on top for access to the MicroTech II controller for viewing display and making keypad entries without opening the panel door.

Motor Protection Module The motor protection system consists of an external control module, located on each compressor, connected to a series of thermistors located in the motor windings and the compressor discharge port. If the windings experience an over-temperature condition or the discharge temperature is excessive, the module will trip and shut off the compressor for a 30-minute time delay.

MicroTech II Unit Controller

Terminal Strips

S1, PS1, PS2 Switches

(4) Compressor Contactors

Grounding Lug

Disconnect Switch

Space for Optional Circuit Breakers and Multi-point Connection

110V Control Transformer (CT)

(3) 24V Controller Transformers


Start-Up and Shutdown

Pre Start-up 1. The chilled-water system should be flushed and cleaned. Proper water treatment is required to

prevent corrosion and organic growth. 2. With main disconnect open, check all electrical connections in control panel and starter to be

sure they are tight and provide good electrical contact. Although connections are tightened at the factory, they can loosen enough in shipment to cause a malfunction.

3. Check and inspect all water piping. Make sure flow direction is correct and piping is made to correct connection on evaporator and condenser.

4. Open all water flow valves to the condenser and evaporator. 5. Flush the cooling tower and system piping to be sure the system is clean. Start evaporator pump

and manually start condenser pump and cooling tower. Check all piping for leaks. Vent the air from the evaporator and condenser water circuit, as well as from the entire water system. The cooler circuit should contain clean, treated, non-corrosive water.

6. Check to see that the evaporator water thermostat sensor is securely installed. 7. Making sure control stop switch S1 is open (off) and pumpdown switches PS1 and PS2 are on

“manual pumpdown,” place the main power and control disconnect switches to “on.” This will energize the crankcase heaters. Wait a minimum of 12 hours before starting the unit.

8. Check compressor oil level. Prior to start-up, the oil level should cover at least one-third of the oil sight glass located in the equalizing line between the compressors or on the compressor.

9. Check water pressure drop across evaporator and condenser, and see that water flow is correct (on pages 15 and 16) per the design flow rates.

10. Check the actual line voltage to the unit to make sure it is the same as called for on the compressor nameplate, within + 10%, and that phase voltage unbalance does not exceed 3%. Verify that adequate power supply and capacity is available to handle load.

11. Make sure all wiring and fuses are of the proper size. Also make sure that all interlock wiring is completed per McQuay diagrams.

12. Verify that all mechanical and electrical inspections by code authorities have been completed. 13. Make sure all auxiliary load and control equipment is operative and that an adequate cooling load

is available for initial start-up.

Start-up 1. Open the compressor discharge shutoff valves until backseated. Always replace valve seal caps. 2. Open the two manual liquid line shutoff valves. 3. Check to see that the unit circuit breakers are in the “off” position. 4. Check to see that the pumpdown switches, PS1 and PS2, are in the “manual pumpdown” position

and the control system switch S1 is in the “off” position. 5. Put the main power and control circuit disconnects to the “on” position. 6. Verify crankcase heaters have operated for at least 12 hours prior to start-up. Crankcase should

be warm to the touch. 7. Check that the MicroTech II controller is set to the desired chilled water temperature. 8. Start the system auxiliary equipment for the installation by turning on the time clock, ambient

thermostat and/or remote on/off switch and water pumps. 9. Check resets of all equipment protection controls. 10. Switch on the unit circuit breakers. 11. Set pumpdown switches PS1 and PS2 to “auto” for restart and normal operation.


12. Start the system by setting the system switch S1 to on. 13. After running the unit for a short time, check the oil level in each compressor crankcase, rotation

of condenser fans (if any), and check for flashing in the refrigerant sight glass. 14. After system performance has stabilized, it is necessary that the “Compressorized Equipment

Warranty Form” (Form No. 206036A) be completed to establish commencement of the warranty period. Be sure to list the pressure drop across both vessels. This form is shipped with the unit and after completion should be returned to the McQuayService Department through your sales representative.

Weekend or Temporary Shutdown Move pumpdown switches PS1 and PS2 to the “manual pumpdown” position. After the compressors have pumped down, turn off the chilled water pump. Note: With the unit in this condition, it will not restart until these switches are turned back on. The unit has one-time pumpdown. It is important that the compressors pump down before the water flow to the unit is interrupted to avoid freeze-up in the evaporator.

Leave S1 on and power to the unit so that the crankcase heaters will remain energized.

Start-up after Temporary Shutdown 1. Start the water pumps. 2. With the control system switch S1 in the “on” position, move the pumpdown switches PS1 and

PS2 to the “auto pumpdown” position. 3. Observe the unit operation for a short time, noting unusual sounds or possible cycling of

compressors. 4. Check compressor crankcase heaters.

Extended Shutdown 1. Close the manual liquid line shutoff valves. 2. After the compressors have pumped down, turn off the water pumps. 3. Turn off all power to the unit. 4. Move the control service switch S1 to the “off” position. 5. Close the discharge shutoff valves on the compressor(s) and the liquid outlet valves at the

condenser. 6. Tag all opened disconnect switches to warn against start-up before opening the compressor

suction and discharge valves. 7. Drain all water from the unit evaporator, condenser, and chilled water piping if the unit is to be

shut down during the winter and exposed to below freezing temperatures. Do not leave the vessels or piping open to the atmosphere over the shutdown period.


Start-up after Extended Shutdown 1. Inspect all equipment to see that it is in satisfactory operating condition. 2. Remove all debris that has collected on the surface of the condenser coils (remote condenser

models) or check the cooling tower, if present. 3. Open the compressor discharge valves until backseated. Always replace valve seal caps. 4. Open the manual liquid line shutoff valves. 5. Check circuit breakers. They must be in the “off” position. 6. Check to see that the pumpdown switches PS1 and PS2 are in the “manual shutdown” position

and the control system switch S1 is in the “off” position. 7. Put the main power and control circuit disconnects to the “on” position. 8. Allow the crankcase heaters to operate for at least 12 hours prior to start-up. 9. Start the chilled water pump and purge the water piping as well as the evaporator in the unit. 10. Start the system auxiliary equipment for the installation by turning on the time clock, ambient

thermostat and/or remote on/off switch. 11. Check that the MicroTech II controller is set to the desired chilled water temperature. 12. Check resets of all equipment protection controls. 13. Switch the unit circuit breakers to “on.” 14. Start the system by setting the system switch S1 to “on.”

CAUTION

Most relays and terminals in the control center are powered when S1 is closed and the control circuit disconnect is on. Therefore, do not close S1 until ready for start-up

or serious equipment damage can occur.

15. Set pumpdown switches PS1 and PS2 to the “auto pumpdown” position for restart and normal operation.

16. After running the unit for a short time, check the oil level in the compressor oil sight glass or in the compressor's equalizing lines for flashing indicating possible refrigerant in the oil (see Maintenance section beginning on page 76).


41.5°F

40.0°F

38.5°F

½ DB

½ DB

EWT 50.0°F

10.0°F

40.0°F

Evap Delta-T Set

LWT Set

Start Delta T

46.5°F

38.0°FStop Delta T

Sequence of Operation

The following sequence of operation is typical for WGZ water chiller models. The sequence can vary slightly depending upon options.

Compressor Heaters With the control circuit power on and the control stop switch S1 off, 115V power is applied through the control circuit fuse Fl to the compressor crankcase heaters HTR1, HTR2, HTR3, and HTR4.

Start-up/Compressor Staging When compressors start and stop. Start Delta is the number of degrees above the Evap LWT setpoint, plus ½ the Dead Band, that determines when the first compressor starts. The Start Delta is in effect for only the first start after all compressors have been off. Additional compressor starts and stops are determined by the LWT in respect to the dead band only. The dead band is automatically set of 30% of the EvapDeltaT selected in menu 3. The following sequence would occur for the settings shown below: EvapDelta T=10.0°F Dead Band=3.0°F StartDelta=5.0°F StopDelta=0.5°F LWT=40.0°F

For a warm start-up, the first compressor will start at any temperature above 46.5°F. Each subsequent compressor will start after the Stage Up Timer has timed out and if the temperature is above the dead band, 41.5°F in this case. If the LWT stays above 41.5°F, all of three remaining compressors will

eventually stage on after the Stage Up Timer times out between each stage. At some point, the chilled water temperature will be dropping and begin to approach the point when compressors should begin staging off, which is the LWT setpoint minus ½ of the Dead Band, 38.5°F in this case. If the LWT remains below LWT setpoint minus ½ Dead Band and the Stage Down Timer times out, additional compressor will stage off. The last compressor will stage off when the LWT falls below the LWT Setpoint minus ½ the Dead Band minus the Stop Delta T. The stop Delta T is in effect for only the last compressor running. If the temperature climbs above 38.5°F all running compressors will remain on. No compressor staging occurs within the Dead Band. The next-on compressor will start when the chilled water temperature reaches 41.5°F and the Stage Up Timer times out.

Which compressor starts and stops. One compressor per circuit will start before starting the second compressor on any circuit. In other words, the compressor with the lowest number of starts will start first. The compressor with the lowest number of starts on the other circuit will start next, so that one compressor on each circuit will be running. The third compressor on will be the compressor on either circuit with the fewest starts. The remaining compressor will be the last on. If a circuit is unavailable for any reason, the second compressor. on the operating circuit will stage on. Only two compressors (on the one circuit) will be operating.

There is a 150 second delay after power-up before any compressor is allowed to start.

When staging down, one compressor on each circuit will be left on until each circuit has only one compressor running. In other words, the compressor, on either circuit, with the most run-hours will stop first. The compressor the most run-hours on the other circuit will stop next. One compressor on each circuit will be running. The third compressor off will be the one, on either circuit, with the most run-hours. The remaining compressor will be the last off. See the following description of pumpdown.


Table 19, Staging in Cool and Glycol Mode Description Occurs When: Action Taken

Stage #1 ON (See Notes Below)

Lvg Evap T > Evap LWT SP + (DB/2) + Startup Delta T

Available compressor with least starts, ON

Stage #2 ON After Stage Up Delay times out then, LVG Evap T > Evap LWT SP + (DB/2)

Available compressor on the other circuit with least starts, ON

Stage #3 ON After Stage Up Delay times out, then LVG Evap T > Evap LWT SP + (DB/2)

Available compressor on either circuit with least starts, ON

Stage #4 ON After Stage Up Delay times out then, LVG Evap T > Evap LWT SP + (DB/2)

Remaining compressor, ON

Stage #4 OFF After Stage Down Delay times out then, LVG Evap T < Evap LWT SP - (CB/2)

Compressor with most run hours, OFF

Stage #3 OFF After Stage Down Delay times out then, LVG Evap T < Evap LWT SP - (DB/2)

Compressor on the other circuit with most run hours, OFF

Stage #2 OFF After Stage Down Delay times out then, LVG Evap T < Evap LWT SP - (DB/2)

Compressor on either circuit with most run hours, OFF

Stage #1 OFF After Stage Down Delay times out then, LVG Evap T < Evap LWT SP - (DB/2)-StopDelta T

Remaining compressor, OFF

Note 1: DB (Dead Band) = Evap Water Delta T x .3

Automatic Pumpdown WGZ units are equipped with single pumpdown control. When the last compressor running on either circuit is to shut off, the liquid line solenoid valve (LLSV) is closed first and the compressor continues to run until the pumpdown pressure is reached at which time the compressor stages off.

When the first compressor on a circuit starts, the LLSV opens simultaneously.

Manual Pumpdown When the Pumpdown Switch is in the pumpdown position, Compressor #3 or #4 (depending on circuit) will shut off. Then the Liquid Line and Hot Gas Bypass Valves will close. The operating compressor will pump out the refrigerant. When the Suction Pressure is at 40 psig, the compressor will stop.

Chilled Water and Condenser Water Pumps The chiller MicroTech II controller can be programmed to start and stop the system chilled water and condenser water pumps. They may also be controlled by the BAS or manually. Programming directions and the sequence of operation can be found beginning on page 57.

Cooling Tower Control The cooling tower fans and/or the tower bypass valve can be controlled by the MicroTech II controller. This provides a simple and direct method to control the unit’s discharge pressure. Programming directions and the sequence of operation can be found on page 69. Some means of discharge pressure control must be installed if the condenser water temperature can fall below 60°F (16°C).

Condenser Fan Control Model AA chillers equipped with air-cooled or evaporative-cooled condensers usually require some form of discharge pressure control. The MicroTech II controller can be programmed to provide this function by cycling condenser fans based on the unit discharge pressure. Directions on the pressure settings can be found on page 69.

ICE In ICE mode, the compressors stage to 100% load until the LWT is less than the ICE LWT SP. Then Compressors #3 and #4 shut down. Following that, Compressors #1 and #2 shut down after going through normal pumpdown on both circuits. There is a programmable, start-to-start, Ice Mode Start Delay that limits the frequency of starts when in the ice mode. The timer can be manually cleared to force a restart.


Standard MicroTech II Controller

General Description The MicroTech II controller’s state-of-the-art design will not only permit the chiller to run more efficiently but will also simplifies troubleshooting if a system failure occurs. Every MicroTech II controller is programmed and tested prior to shipment to assist in a trouble-free start-up. The MicroTech II controller can be used to cycle fans on remote air-cooled condensers for head pressure control when the setpoint Water Cooled=N is selected in one of the setpoint menu screens. Water Cooled=Y sets the chiller for operation with the water-cooled condenser.

Operator-friendly The MicroTech II controller menu structure is separated into three distinct categories, which provide the operator or service technician with a full description of 1) current unit status, 2) control parameters (setpoints), and 3) alarms. Security protection prevents unauthorized changing of the setpoints and control parameters.

The MicroTech II controller continuously performs self-diagnostic checks, monitoring all system temperatures, pressures and protection devices, and will automatically shutdown a compressor, a refrigerant circuit or the entire unit should a fault occur. The cause of the shutdown and date stamp are retained in memory and can be easily displayed in plain English for operator review, which is an extremely useful feature for troubleshooting. In addition to displaying alarm diagnostics, the MicroTech II chiller controller also provides the operator with a warning of pre-alarm conditions.

Staging The four scroll compressors are staged on and off as a function of leaving chilled water temperature, number of starts and run-hours. See Sequence of Operation.

Equipment Protection The unit is protected by alarms that shut it down and require manual reset, and also by limit alarms that limit unit operation in response to some out-of-limit condition. Shut down alarms activate an alarm signal that can be wired to a remote device.

Unit Enable Selection Enables unit operation from local keypad or digital input.

Unit Mode Selection Selects standard cooling, ice, glycol, or test operation mode.


Keypad/Display A 4-line by 20-character/line liquid crystal display and 6-key keypad is mounted on the unit controller. Its layout is shown below.

Figure 23, Keypad and Display in MENU Mode

Air Conditioning

ALARMVIEW

SET

<<<

The four arrow keys (UP, DOWN, LEFT, RIGHT) have three modes of use. 1. Scroll between data screens as indicated by the arrows (default mode). 2. Select a specific data screen in a hierarchical fashion using dynamic labels on the right side of the

display (this mode is entered by pressing the MENU key). 3. Change field values in edit mode according to the following table: LEFT Default RIGHT Cancel UP Increment DOWN Decrement These four edit functions are indicated by one-character abbreviation on the right side of the display (this mode is entered by pressing the ENTER key).

Inputs/Outputs

Table 20, Analog Inputs C1 = Refrigerant Circuit #1, C2 = Refrigerant Circuit #2, UT = Unit

# Description Type Signal Source Range 1 Evaporator Refrigerant Pressure #1 C1 0.5 - 4.5 VDC (NOTE 1) 0 to 132 psi 2 Evaporator Refrigerant Pressure #2 C2 0.5 - 4.5 VDC (NOTE 1) 0 to 132 psi 3 Condenser Refrigerant Pressure #1 C1 0.5 - 4.5 VDC (NOTE 1) 3.6 to 410 psi

4 Leaving Evaporator Water Temperature UT Thermister (10k at 77°F, 25°C) -58 to 212°F

5 Condenser Entering or Outside Ambient Temperature (NOTE 2) UT Thermister (10k at 77°F,

25°C) -58 to 212°F

6 Condenser Refrigerant Pressure #2 C2 0.1 to 0.9 VDC 3.6 to 410 psi 7 Reset of Leaving Water Temperature UT 4-20 mA Current 0-(10 to 60°F) 8 Demand Limit UT 4-20 mA Current 0-100 % Load

9 Compressor Suction Temperature #1 C1 Thermister (10k at 77°F, 25°C) -58 to 212°F

10 Compressor Suction Temperature #2 C2 Thermister (10k at 77°F, 25°C) -58 to 212°F

NOTES: 1. Value at the converter board input. Value at the converter board output is 0.1 VDC – 0.9 VDC. 2. If Water Cooled = Y, then Entering Condenser. If Water Cooled = N, then Outside Ambient.

Menu Key Key to Screen Pathway

"Enter" Key Arrow Keys


Table 21, Analog Outputs # Description Output Signal Range 1 Cooling Tower Bypass Valve Position 0 to 10 VDC 0 to 100% Open 2 Cooling Tower VFD Speed 0 to 10 VDC 0 to 100%

Table 22, Digital Inputs C1 = Refrigerant Circuit #1, C2 = Refrigerant Circuit #2, UT = Unit

# Description Type Signal Signal 1 Unit OFF Switch UT 0 VAC (Stop) 24 VAC (Auto) 2 Pump Down Switch #1 C1 0 VAC (Stop) 24 VAC (Start) 3 Evaporator Water Flow Switch UT 0 VAC (No Flow) 24 VAC (Flow) 4 Motor Protection #1 C1 0 VAC (Fault) 24 VAC (No Fault) 5 Open 6 Pump Down Switch #2 C2 0 VAC (Stop) 24 VAC (Start) 7 Motor Protection #2 C2 0 VAC (Fault) 24 VAC (No Fault) 8 Open 9 Phase Voltage Fault #1 (See Note 1) C1 0 VAC (Fault) 24 VAC (No Fault)

10 Phase Voltage Fault #2 (See Note 1) C2 0 VAC (Fault) 24 VAC (No Fault) 11 Ground Fault Prot. #1 (See Note 2) C1 0 VAC (Fault) 24 VAC (No Fault) 12 Ground Fault Prot. #2 (See Note 2) C2 0 VAC (Fault) 24 VAC (No Fault) 13 Remote Start/Stop UT 0 VAC (Stop) 24 VAC (Start) 14 Condenser Water Flow Switch UT 0 VAC (No Flow) 24 VAC (Flow)

15 Mechanical High Pressure #1 C2 0 VAC (High Pressure/Off) 24 VAC (OK )

16 Mechanical High Pressure #2 C2 0 VAC (High Pressure/Off) 24 VAC (OK )

17 Ice Mode Switch UT 0 VAC (Normal) 24 VAC (Ice) 18 Open

Note 1: See Equipment Protection Alarms Table for “Phase Voltage Protection”. Units with single point electrical connection will have one PVM with Inputs 9 and 10 wired together. Units with multiple point connection will have two PVM’s with Input 9 for Electrical Circuit #1 and Input 10 for Electrical Circuit #2.

Note 2: See Equipment Protection Alarms Table for “Ground Fault Protection”. Units with single point electrical connection will have one GFP with Inputs 11 and 12 wired together. Units with multiple point connection will have two GFP’s with Input 11 for Electrical Circuit #1 and Input 12 for Electrical Circuit #2.

Table 23, Digital Outputs C1 = Refrigerant Circuit #1, C2 = Refrigerant Circuit #2, UT = Unit # Description Type Load Output OFF Output ON

1 Alarm C1,C2,UT Alarm Indicator Alarm OFF Alarm ON

2 Evaporator Water Pump UT Pump Contactor Pump OFF Pump ON

3 Condenser Fan #1 – Water Cooled = N / Condenser Water Pump – Water Cooled = Y

C1 / UT

Fan Contactor/ Pump Contactor Fan OFF Fan ON

4 Motor Control Relay #1 = Compr#1 C1 Starter Compressor OFF Compressor ON 5 Motor Control Relay #3 = Compr#3 C1 Starter Compressor OFF Compressor ON

6 Condenser Fan #3– Water Cooled =N /Tower Fan #2-Water Cooled=Y

C1 / UT Fan Contactor Fan OFF Fan ON

7 Liquid Line #1 C1 Solenoid Cooling OFF Cooling ON

8 Condenser Fan #2 – Water Cooled =N /Tower Fan #1-Water Cooled=Y

C2 / UT Fan Contactor Fan OFF Fan ON

9 Motor Control Relay #2 = Compr#2 C2 Starter Compressor OFF Compressor ON 10 Motor Control Relay #4 = Compr#4 C2 Starter Compressor OFF Compressor ON 11 Condenser Fan #4 C2 Fan Contactor Fan OFF Fan ON 12 Liquid Line #2 C2 Solenoid Cooling OFF Cooling ON 13 Condenser Fan #5 C1 Fan Contactor Fan OFF Fan ON 14 Hot Gas Bypass #1 C1 Solenoid Cooling OFF Cooling ON 15 Hot Gas Bypass #2 C2 Solenoid Cooling OFF Cooling ON 16 Condenser Fan #6 C2 Fan Contactor Fan OFF Fan ON 17 Condenser Fan #7 C1 Fan Contactor Fan OFF Fan ON 18 Condenser Fan #8 C2 Fan Contactor Fan OFF Fan ON


Setpoints The following parameters are remembered during power off, are factory set to the Default value, and can be adjusted to any value in the Range column.

The PW (password) column indicates the password level that must be active in order to change the setpoint. Passwords are as follows:

O = Operator [0100] M = Manager [2001]

Table 24, Setpoints Description Default Range PW

Unit Enable OFF OFF, ON O Unit Mode COOL COOL, COOL w/Glycol, ICE w/Glycol O Control source DIGITAL INPUT KEYPAD, BAS, DIGITAL INPUT O Available Modes COOL COOL, COOL w/Glycol, /ICE w/Glycol M Display Units °F/psi °F/psi, °C/kPa O Language ENGLISH ENGLISH, (TBD) O BAS Protocol NONE NONE, BACnet, LonWorks, Modbus M Evap LWT (COOL & GLYCOL) 44. 0°F 20.0 to 60.0 °F O Ice LWT (ICE) 40. 0°F 20.0 to 40.0 °F O Evap Delta T 10. 0°F 6.0 to 16.0 °F O Startup Delta T 2.0°F 1.0 to 10.0 °F O * Water Cooled N N,Y M * Phase Voltage Protection N N,Y M * Ground Fault Protection N N,Y M * Set at Factory Speedtrol Option N N,Y M Staging Stage Up Delay 120 90 to 240 sec M Stage Down Delay 30 20 to 60 sec M Timers Evap Flow Proof 5 sec 3 to 120 sec M Low Evap Pressure Delay 30 sec 15 sec to 30sec M Start-Start 15 min 10 to 60 min M Stop-Start 5 min 3 to 20 min M Alarms Evaporator Freeze 36.0 °F 18 to 42 °F M Condenser Freeze 34.0 °F 18 to 42 °F M Low Evap Pressure 58 psi 30 to 60 psi M Low Evap Pressure-Hold 59 psi 31 to 65 psi M Low Evap Pressure-Unload 59 psi 31 to 65 psi M High Condenser Stage Down 370 psi 365 to 375 psi M High Condenser Pressure 380 psi 380 to 390 psi M Low Ambient Lockout 35.0 °F –2 to 60 °F M Condenser Fans (Water Cooled = N) C1/ C2 - Stage #1 / #2 On (OAT < 75°F) 150psi 140 to 200 psi M C1/ C2 - Stage #3 / #4 On 270 psi 220 to 330 psi M C1/ C2 - Stage #5 / #6 On 290 psi 220 to 330 psi M C1/ C2 - Stage #7/ #8 On 310 psi 220 to 330 psi M C1/ C2 - Stage #1/ #2 Off Off Off with Stage #1 M C1/ C2 - Stage #3/ #4 Off 170 psi 150 to 220 psi M C1/ C2 - Stage #5/ #6 Off 180 psi 150 to 220 psi M C1/ C2 - Stage #7/ #8 Off 200 psi 150 to 220 psi M Description Default Range PW Cooling Tower (Water Cooled = Y) Tower Control None None, Temperature M Tower Stages 2 0 to 2 M Stage Up Time 2 min 1 to 60 min M Stage Down Time 5 min 1 to 60 min M Stage Differential 3.0 °F 1.0 to 10.0 °F M Stage #1 On 70 °F 40 to 120 °F M Stage #2 On 75 °F 40 to 120 °F M (continued next page)


Table 23 Continued Cooling Tower (Water Cooled = Y) Valve / VFD

Valve/VFD Control None None, Valve Setpoint, Valve Stage, VFD Stage, Valve SP/VFD Stage M

Valve Setpoint 65 °F 60 to 120 °F M Valve Deadband 2.0 °F 1.0 to 10.0 °F M Stage Down @ 20% 0 to 100% M Stage Up @ 80% 0 to 100% M Valve Control Range (Min) 10% 0 to 100% M Valve Control Range(Max) 90% 0 to 100% M Valve Type NC (To Tower) Normally Closed (NC), Normally Open (NO) M Minimum Start Position 0% 0 to 100% M Minimum Position @ 60 °F 0 to 100 °F M Maximum Start Position 100% 0 to 100% M Maximum Position @ 90 °F 0 to 100 °F M Error Gain 25 10 to 99 M Slope Gain 25 10 to 99 M

Equipment Protection (Shutdown) Alarms Equipment protection alarms trigger a rapid compressor shutdown. The following table identifies each equipment protection alarm, gives the condition that causes the alarm to occur, and states the action taken because of the alarm. Most equipment protection alarms require a manual reset. These alarms will energize a remote alarm if the unit is so wired in the field.

Table 25, Equipment Protection Alarms NOTE: SP = Setpoint NOTE : UT = Rapid Stop for the entire unit (Both Circuits), CT = Rapid Stop for that circuit only

Description Occurs When: Action Taken Reset

No Evaporator Water Flow

Evap Pump State = RUN AND Evap Flow Digital Input = No Flow & High Condenser Pressure for > Evap Flow Proof SP]

Rapid Stop UT Manual

No Condenser Water Flow

Cond Flow Digital Input = No Flow for > Evap Flow Proof] Note: Water Cooled = Y Only

Rapid Stop UT Manual

Low Evaporator Pressure

Evaporator Press < Low Evap Pressure SP start Low Evap Pressure Time Delay – if after Time Delay if Evap Press > SP continue else stop

Rapid Stop CT Manual

High Condenser Pressure

Condenser Press & Condenser Flow > High Condenser Pressure SP


Mechanical High Pressure

For C1, Motor Start #1 On & Digital Input = High Pressure For C2, Motor Start #2 On & Digital Input = High Pressure


Motor Protection Digital Input = High Motor Temperature On Power Up – Delay 150 Sec. before checking


Phase Voltage Protection (optional)

If Phase Voltage Protection = Y, Then Digital Input = Phase/Voltage Problem

Rapid Stop CT

Ground Fault Protection (optional)

If Ground Fault Protection = Y, Then Digital Input = Ground Fault Protection Problem


Re-Start Fault Re-Start = Third Time Rapid Stop UT Manual

Evap. Freeze Protect Evap LWT < Evaporator Freeze SP Rapid Stop CT Manual

Leaving Evap. Water Temp. Sensor Fault Sensor shorted or open Rapid

Stop UT Manual

Evaporator Pressure Sensor Fault Sensor shorted or open Rapid

Stop CT Manual

Condenser Pressure Sensor Fault Sensor shorted or open Rapid

Stop CT Manual

Condenser Entering or Outside Ambient Temp. Sensor Fault

Sensor is open or shorted Rapid Stop UT Manual


Limit Alarms The following alarms do not cause a rapid shutdown but limit operation of the chiller in some way as described in the Action Taken column. These alarms do not trigger a remote alarm signal. They do appear in the Active Alarm menu, are logged, and light the Alarm LED.

Table 26, Limit Alarms NOTE: SP = Setpoint NOTE: UT = Rapid Stop for the entire unit (Both Circuits), CT = Rapid Stop for that circuit only

Description Occurs When: Action Taken Reset High Condenser Pressure Stage Down

Pressure > High Condenser Stage Down setpoint

Stage off lag compressor on the circuit

Condenser Press drops below (SP – 100psi)

CT

Low Ambient Lockout

Outside Ambient < Low Ambient Lockout SP Note: Water Cooled = N Only

Stage down & Shutoff Outside Ambient > Low Amb Lockout (SP + 5ºF)

UT

Low Evaporator Pressure – Hold

Pressure < Low Evap Pressure–Hold setpoint

Inhibit staging on lag compressor on the circuit

Evap Press rises above (SP + 8psi) CT

Low Evaporator Pressure – Unload

Pressure < Low Evap Pressure–Unload setpoint

Stage off lag compressor on the circuit

Evap Press rises above (SP + 10 psi + Stage Up Delta T)

CT

Condenser Freeze Protect

Cond Sat Refr Temp < Condenser Freeze SP AND Cond Pump State = OFF Note: Water Cooled = Y Only

Start condenser pump Cond Sat Refr Temp > (Condenser Freeze SP + 2°F)

UT

Unit Enable • Enabling and disabling the chiller is controlled by the Unit Enable Setpoint with options of OFF

and ON. This setpoint can be altered by the keypad, BAS, Unit OFF input, and Remote input. The Control Source Setpoint determines which sources can change the Unit Enable Setpoint with options of SWITCHES, KEYPAD or NETWORK.

Changing the Unit Enable Setpoint can be accomplished according to the following table.

Table 27, Unit Enable Combinations NOTE: An “x” indicates that the value is ignored. Unit Off

Input Control Source

Setpoint Remote Input

Keypad Entry

BAS Request

Unit Enable

OFF x x x x OFF x SWITCHES OFF x x OFF

ON SWITCHES ON x x ON ON KEYPAD x OFF x OFF ON KEYPAD x ON x ON ON NETWORK x x OFF OFF ON NETWORK OFF x x OFF ON NETWORK ON x ON ON

Unit Mode Selection The overall operating mode of the chiller is set by the Unit Mode Setpoint with options of COOL, COOL w/Glycol, ICE w/Glycol, and TEST. This setpoint can be altered by the keypad, BAS, and Mode input. Changes to the Unit Mode Setpoint are controlled by two additional setpoints. • Available Modes Setpoint: Determines the operational modes available at any time with options

of COOL, COOL w/Glycol, COOL/ICE w/Glycol, and TEST. • Control Source Setpoint: Determines the source that can change the Unit Mode Setpoint with

options of KEYPAD, NETWORK, or SWITCHES.


Table 28, Unit Mode Combinations Changing the Unit Mode Setpoint can be accomplished according to the following table. NOTE: An “x” indicates that the value is ignored. Control Source

Setpoint Mode Input Keypad Entry BAS

Request Available Modes

Setpoint Unit Mode

x x x x COOL COOL x x x x COOL w/Glycol COOL w/Glycol

SWITCHES OFF x x COOL/ICE w/Glycol COOL w/Glycol SWITCHES ON x x COOL/ICE w/Glycol ICE w/Glycol

KEYPAD x COOL w/Glycol x COOL/ICE w/Glycol COOL w/Glycol KEYPAD x ICE w/Glycol x COOL/ICE w/Glycol ICE w/Glycol

NETWORK x x COOL COOL/ICE w/Glycol COOL w/Glycol NETWORK x x ICE COOL/ICE w/Glycol ICE w/Glycol

x x x x TEST TEST

Low Ambient Start (Remote Condenser Only) If Water Cooled = Y, then this function is not applicable.

If SpeedTrol = N, this step is bypassed and unit starts in the normal operation. If the SpeedTrol = Y then unit starts per table below. This step will bypass the “Low Evaporator Pressure” alarm until Low Ambient Start is completed. When there is a call for Cooling the following steps are used.

Table 29, Low Ambient Start Sequence NOTE: CT = Rapid Stop for that circuit only Description Occurs When: Action Taken

Check #1 After 15 Seconds after starting first compressor, If the Evap Press is < 0.48 times the Low Evap Pressure SP take action, else continue

Rapid Stop – See Low Ambient Re-Start below

CT

Check #2 After 15 Seconds after Check #1, If the Evap Press is < 0.66 times the Low Evap Pressure SP take action, else continue (30 Sec Total)


CT

Check #3 After 15 Seconds after Check #2, If the Evap Press is < 0.83 times the Low Evap Pressure SP take action, else continue (45 Sec Total)


CT

Check #4 After 15 Seconds after Check #3, If the Evap Press is < Low Evap Pressure SP take action, else continue in normal operation (60 Sec Total)


CT

Low Ambient Re-Start If the Evap Pressure fails during the low ambient start, the controller waits until the anti-cycle timers expire then tries to re-start. It will attempt a start 3 times, and reset the counter if unit continues in normal operation. If it fails on the third attempt, it will initiate the Low Ambient Re-Start Alarm Fault (Manual Reset).

Automatic Adjusted Limits The following are setpoints that will be changed are based on the option selected.

Evaporator Leaving Water Temperature Mode Range Unit Mode = Cool 40 to 60°F Unit Mode = Glycol, Ice 20 to 60°F


Evaporator Freeze Temperature Mode Range Unit Mode = Cool 36 to 42°F Unit Mode = Glycol, Ice 18 to 42°F

Low Evaporator Pressure Mode Range Unit Mode = Cool 55 to 65 Psig Unit Mode = Glycol, Ice 30 to 65 Psig

Low Evaporator Pressure Hold and Unload Mode Range Unit Mode = Cool 55 to 65 Psig Unit Mode = Glycol, Ice 31 to 65 Psig

Low Ambient Lockout Temperature SpeedTrol Range SpeedTrol = N 35 – 60°F SpeedTrol = Y -2 – 60°F

Staging Parameters Lockouts There are conditions that shall prevent a start when the unit status is AUTO.

Low Ambient Lockout If the unit status is AUTO, but no compressors have started, and the outside ambient temperature drops below the low ambient lockout setpoint, the unit will transition to the Low Ambient Lockout state. This condition will not trigger an alarm. The condition will be indicated by showing the unit status as “Low Amb Lockout”.

Compressor start will be delayed until the outside ambient temperature rises to the setpoint plus 5 degrees F.

Wait For Evap Water Flow If the unit status is AUTO and the evap pump status is START, then the unit will wait for the evaporator flow switch to close. During this time, the condition will be indicated by showing the unit status as “Wait For Flow”. The unit will remain in this state indefinitely until the flow switch closes for a 30 second duration.

Capacity Overrides The following conditions override the capacity control mode when the chiller is in the cool or ice mode. The purpose of the overrides is to keep the unit online (although at reduced capacity) during certain abnormal operating condition. If and when the "off" condition returns to normal, the override is eliminated and the unit returns to normal operation based on the capacity control.

Low Evaporator Pressure If the evaporator pressure drops below the Low Evaporator Pressure Hold setpoint and only one compressor on that circuit is running, the second compressor is prevented from starting.

If the evaporator pressure drops below the Low Evaporator Pressure Unload setpoint, and both compressors on the circuit are running, the “first off” compressor on that circuit is shut off.

Maximum LWT Rate The maximum rate at which the leaving water temperature can drop is limited at all times by the Maximum Rate setpoint (2°F/minute). If the rate exceeds this setpoint, no more compressors will be started until the pulldown rate is less than 2°F/minute.


High Condenser Pressure If the discharge pressure rises above the High Condenser Pressure Unload setpoint, and both compressors on the circuit are running, the “first off” compressor on the circuit is shut off.

Digital Output Control Each digital output is be controlled according to the following rules. All outputs are initialized to OFF at power on.

Alarm – (Terminals J12 – NO1) This output is turned ON when any Equipment Protection ALARM occurs. It is turned OFF when all alarms have been cleared.

Evaporator Pump – (Terminals J12 – NO2) An Evaporator Water Pump output is ON if the Evap State is set to START or RUN.

Hot Gas Bypass Solenoid – (Terminals J21 – NO14, J21 – NO15) This output shall be ON when the Lead Compressor per Circuit is the only compressor ON, except during Pumpdown.

This output shall be ON when the Compressors are ON. It shall be OFF for all other cases.

Digital Output Control Each digital output is controlled according to the following rules. All outputs are initialized to OFF at power on.

Fan #1 to #8 (Air-Cooled Condensers) [Water Cooled = N] - Condenser Fans Staging is based on condenser pressure as selected by Fan Stage On & Off setpoints. Fans 1, 3, 5 and 7 are for circuit 1, and fans 2, 4, 6, and 8 are for circuit 2. Fans 1 and 2 start with the first compressor on the respective circuit when the ambient temperature is greater than 75°F. Below 75°F, these fans start when the condenser pressure gets up to the stage on setpoint.

Condenser Pump and Tower Fans (Water-Cooled Condenser) [Water Cooled = Y] - Condenser Pump is on with first Compressor on. Tower fan control is active when the Tower Control setpoint is set to Temperature and the condenser pump is in the RUN state. Staging is based on Entering Condenser Water Temperature (ECWT). Operation depends on the following parameters.

• Condenser pump state • ECWT • Stage up and stage down timer values • Tower setpoints (Tower Control, Tower Stages, Stage Up Time, Stage Down Time, Stage

Differential, Stage #1 ON, Stage #2 ON, Stage Down @, Stage Up @) When the condenser pump starts, the stage-up timer starts. The first stage turns ON when the following conditions are met:

• The stage-up timer completes • The ECWT is > Stage #1 ON setpoint • Bypass valve position is > the Stage Up @ setpoint (only if Valve/VFD Control setpoint = Valve

Stage) Additional stages turn on (up to the number specified by the Tower Stages setpoint) when above conditions are met for the next stage plus the following condition:


• VFD Speed is > the Stage Up @ setpoint (only if Valve/VFD Control setpoint = VFD Stage OR Valve SP/VFD Stage)

Down staging occur when the following conditions are met:

• The stage-down timer completes • The ECWT is < Stage #X ON (Temp) setpoint – Stage Differential (Temp) setpoint • Bypass valve position is < the Stage Down @ setpoint (only if Valve/VFD Control setpoint =

Valve Stage) • VFD Speed is < the Stage Down @ setpoint (only if Valve/VFD Control setpoint = VFD Stage

OR Valve SP/VFD Stage) Each stage-up or stage-down event restarts both the stage-up and-stage down timers. Only one fan output is switched at a time (except that all outputs switch OFF when the condenser pump state equals OFF).

Analog Output Control Each analog output is controlled according to the following rules/algorithms and in accordance with whether the Compressor Mode setpoint is set to AUTO or MANUAL (normal operation). All outputs shall be initialized to 0 at power on.

Cooling Tower Bypass Valve When the Valve/VFD Control setpoint is set to None or VFD Stage, this output is set to 0. Otherwise, it is controlled as described below.

Initial Valve Position When the condenser pump is not in the RUN state, the valve output is set as a function of entering condenser water temperature (ECWT) per the following graph.

Max Position @Setpoint

(90°F)

Min Position @

(60°F)

Min Start Position(10%)

Initial Valve Position(values are examples only)

Max Start Position(90%)

Setpoint

Setpoint Setpoint

Operation After Start When the condenser pump is in the RUN state, the valve output is controlled in one of two modes as specified by the Valve/VFD Control setpoint. The controlled parameter is the condenser entering water temperature. When the desired output signal varies from 0 to 100%, the output voltage will vary as shown below.

• 0 to 10 VDC (Valve Type = NC) • 10 to 0 VDC (Valve Type = NO)


Valve Setpoint Mode This mode is operational when the Valve/VFD Control setpoint is set to Valve Setpoint or Valve SP/VFD Stage. In this mode the valve output is varied with a proportional-derivative (PD) algorithm (with deadband) in order to maintain the controlled parameter (CP) at the desired value. The output is always limited between the Valve Control Range (Min) setpoint and the Valve Control Range (Max) setpoint. A valve increment is computed once every 5 seconds according to the following equation.

• Increment = [(Error) * (Error Gain setpoint)] + [(Slope) * (Slope Gain setpoint)] Where: Error = ECWT – Valve Setpoint Slope = (Present CP) – (Previous CP)

When the Error is > the Valve Deadband setpoint, the valve position analog output (% of full scale) is updated according to the following equation. • New %Position = Old %Position + Increment/10.

Valve Stage Mode This mode is only operational when the Valve/VFD Control setpoint is set to Valve Stage. In this mode the valve output is controlled as for Valve Setpoint mode (above) except that the active setpoint for the controlled parameter is selected according to the following table.

# Of Fans ON Active Setpoint 0 Valve Setpoint 1 Stage #1 ON 2 Stage #2 ON 3 Stage #3 ON 4 Stage #4 ON

Cooling Tower Fan VFD When the Valve/VFD Control setpoint is set to None, Valve Setpoint, or Valve Stage, this output is set to 0. Otherwise, it is controlled in a manner identical to Valve Stage Mode (above) except that (1) it is kept at zero until the first fan stage is ON and (2) the following setpoints do not apply.

• Valve Control Range (Min) • Valve Control Range (Max) • Valve Type

Evaporator Water Pump State Control Operation of the evaporator pump is controlled by the state-transition diagram shown below. A state variable (Evap State) is used to maintain the current state (OFF, START, or RUN). The fixed 30 second timer will start when flow is first indicated by the Evaporator Water Flow Switch digital input. This timer is considered expired after 30 seconds.

OFF

RUN STARTTEST: Flow OK for 30 Seconds

TEST: Unit alarm (except evapfreeze) ORCircuit alarm on both circuits ORUnit enable = off ORCircuit PumpDn Switch = off for allcircuits (and pumpdn completed)

TEST: Unit Enable = OnAND at least one circuit isenabled and not in alarmstate OREvap Freeze Protection

Power ON

TEST: Unit alarm (except evapfreeze) ORCircuit alarm on both circuits ORUnit enable = off ORCircuit PumpDn Switch = off for allcircuits (and pumpdn completed)


Condenser Water Pump State Control Operation of the Condenser pump is controlled by the state-transition diagram shown below. A state variable (Cond State) is used to maintain the current state (OFF, START, or RUN).

Using the Controller Getting Started There are two basic procedures to learn in order to utilize the MicroTech II controller:

1. Navigating through the menu matrix to reach a desired menu screen and knowing where a particular screen is located.

2. Knowing what is contained in a menu screen and how to read that information or how to change a setpoint contained in the menu screen.

1. Navigating Through the Menus The menus are arranged in a matrix of screens across a top horizontal row. Some of these top-level screens have sub-screens located under them. The general content of each screen and its location in the matrix are shown in Figure 25. (A detailed description of each menu begins on page 61.) There are two ways to navigate through the menu matrix to reach a desired menu screen.

One is to scroll through the matrix from one screen to another using the four ARROW keys.

The other way is to use shortcuts to work through the matrix hierarchy. From any menu screen, pressing the MENU key will take you to the top level of the hierarchy. The display will show ALARM, VIEW, and SET as shown in Figure 23. This corresponds to the second row of screens on Figure 25. One of these groups of screens can then be selected by pressing the key connected to it via the pathway shown in Figure 23 on page 48.

For example, selecting ALARM will go the next row of menus under ALARM (ALARM LOG or ACTIVE ALARM). Selecting VIEW will go the next level of screens under VIEW (VIEW UNIT STATUS or VIEW UNIT TEMP). Selecting SET will go to a series of screens for looking at and changing setpoints.

After pressing the MENU button, the top-level menu screen will show: < ALARM< VIEW< SET<

OFF

RUN STARTTEST: Flow OK

TEST: Unit alarm ORCircuit alarm on both circuits ORUnit enable = off ORCircuit PumpDn Switch = off for allcircuits (and pumpdn completed) ORCondenser Freeze alarm reset

Power ON

TEST: Unit alarm ORCircuit alarm on both circuits ORUnit enable = off ORCircuit PumpDn Switch = off for allcircuits (and pumpdn completed)

TEST: Any Comp = ON ORCondenser Freeze Alarm


After pressing the “VIEW” menu button, a menu screen will show: VIEW < COMPRESSOR

< UNIT< EVAPORATOR< FANS

After pressing the “EVAPORATOR” menu button, the selected data screen will show: VIEW EVAP

(screen data)(screen data)(screen data)

The arrow keys will automatically return to the “scroll” mode at this time.

MENU Key The MENU key is used to switch between the shortcut method (known as the MENU mode and as shown in Figure 23) and scrolling method (known as the SCROLL mode). The MENU mode is the shortcut to specific groups of menus used for checking ALARMS, for VIEWING information, or to SET setpoint values. The SCROLL mode allows the user to move about the matrix (from one menu to another, one at a time) by using the four ARROW keys. A typical menu screen is shown in Figure 24. Pressing the MENU key from any menu screen will automatically return you to the MENU mode.

Figure 24, Display in the Shortcut (SCROLL) Mode and Keypad Layout

Air Conditioning

VIEW UNIT STATUSUnit = COOLCompr. #1/#2=OFF/OFFEvap Pump = RUN

ENTER Key Pressing the ENTER key changes the function of the ARROW keys to the editing function as shown below:

LEFT key Default, changes a value to the factory-set default value. RIGHT key Cancel, cancels any change made to a value and returns to the original setting. UP key Increment, increases the value of the setting DOWN key Decrement decreases the value of a setting. These four edit functions are indicated by one-character abbreviation on the right side of the display (this mode is entered by pressing the ENTER key).

Most menus containing setpoint values have several different setpoints shown on one menu. When in a setpoint menu, the ENTER key is used to proceed from the top line to the second line and on downward. The cursor will blink at the entry point for making a change. The ARROW keys (now in the edit mode) are used to change the setpoint as described above. When the change has been made, press the ENTER key to enter it. Nothing is changed until the ENTER key is pressed.

For example, to change the chilled water setpoint:

1. Press MENU key to go to the MENU mode.

2. Press SET (the UP Key) to go to the setpoint menus.

3. Press UNIT SPs (the Right key) to go to setpoints associated with unit operation.

MENU Key

ENTER Key ARROW Keys


4. Press the DOWN key to scroll down through the setpoint menus to the third menu which contains Evap LWT=XX.X°F.

5. Press the ENTER key to move the cursor down from the top line to the second line in order to make the change.

6. Use the ARROW keys (now in the edit mode as shown above) to change the setting. 7. When the desired value is achieved, press ENTER to enter it and also move the cursor down. At this point, the following actions can be taken: 1. Change another setpoint in this menu by scrolling to it with the ENTER key. 2. Using the ENTER key, scroll to the first line in the menu. From there the ARROW keys can be

used to scroll to different menus.

Menu Screens Various menus are shown in the controller display. Each menu screen shows specific information, in some cases menus are only to view status of the unit, in some cases for checking alarms, and in some cases they are used to set setpoint values that can be changed. The menus are arranged in a matrix of screens across a top horizontal row. Some of these top-level screens have sub-screens located under them. The content of each screen and its location in the matrix are shown in Figure 25. A description of each menu begins on page 61. The arrow keys on the controller are used to navigate through the menus. The keys are also used to change numerical setpoint values contained in certain menus.

Figure 25, Menu Matrix "MENU"

"VIEW" MENUS

UNIT CIRCUITS REFRIGERANT FANS

VIEW UNIT

STATUS

(1)

VIEW UNIT

TEMP

(1)

VIEW

CIRC #1

STATUS

(1)

VIEW

CIRC #2

STATUS

(1)

VIEW

REFRIGERANT

CIRCUIT #1

(1)

VIEW

REFRIGERANT

CIRCUIT #2

(1)

VIEW FAN/TOWER

(1)

VIEW UNIT

STATUS

(5)

VIEW UNIT

TEMP

(2)

VIEW

COMP #1

STATUS

(3)

VIEW

CIRC #2

STATUS

(3)

VIEW EVAP

(2)

VIEW EVAP

(2)

VIEW FAN/TOWER

(n)

(Right side of matrix continued from above)m

"ALARM" MENUS "SET" MENUS

ALARM LOG

(LAST)

TYPE, TIME

ACTIVE ALARM (1)

TYPE, TIME

SET UNIT SPs, (1) SET COMP SPs

(1)

SET LIMIT ALARMS

(1

SET FANS (1)

STAGES

FANTROL

SET

TOWER (1)

ALARM LOG

(NEXT TO LAST)

ACTIVE ALARM(2)

TYPE, TIME

ADDITIONAL

SET UNIT SPs, (2) SET COMP SPs

(2)

SET LIMIT ALARMS

(2)

SET FANS (2)

STAGE ON

SET

TOWER (2)

ALARN LOG

(SECOND TO

LAST)

ACTIVE ALARM(3)

CLEAR/VIEW

SET UNIT SPs, (3) SET LIMIT ALARMS

(3)

SET FANS (3)

STAGE OFF

SET

TOWER (3)

ALARM LOG

LAST 25 SHOWN

SET UNIT SPs, (4)

(to 13)

SET TOWER

(to n)

Selection can be made within the matrix by using the LEFT/RIGHT keys to move between columns and the UP/DOWN keys to move between rows.

⇐ Continued ⇐


Menu Descriptions This section contains information on each screen. The menu screens are in order of the matrix in Figure 25 on page 60 going from left to right and down when there are sub-menus. Many menus are self-explanatory. A Setpoint menu allows selection of whether the unit has a water-cooled condenser, WaterCooled = Y (Yes) or a remote condenser, WaterCooled = N (No). This selection will alter some menus as appropriate to the type of condenser.

Screen Definitions – MENU Top level menu:

< ALARM< VIEW< SET<

ALARM menu: ALARM < ACTIVE

< LOG<<

VIEW menu: VIEW < COMPRESSOR

< UNIT< EVAPORATOR< FANS/TOWER

VIEW UNIT menu: VIEW < TEMPUNIT < STATUS

< REFRIGERANT

SET menu: SET < ALARM LIMITS

< UNIT SPs< COMPRESSOR SPs< FANS/TOWER SPs

Screen Definitions – VIEW View Unit Status VIEW UNIT STATUS (1)AutoCooling Stage = 0Evap Pump = RUNUnit states can be OFF, COOL, GYLCOL, ICE, or ALARM as determined from the Unit Mode setpoint, the Unit Enable, and the presence of an alarm.

Circuit states can be OFF/OFF, ON/OFF, OFF/ON, and ON/ON. Evaporator Pump States can be OFF, STRT, or RUN.


When more than one screen are stacked (i.e., relate to each other on the same subject), they are numbered sequentially with the numbers appearing in the upper-right corner. VIEW UNIT STATUS (2)Demand Limit=Stg 4Network Limit=Stg 4

VIEW UNIT STATUS (3)Stg Up Delay=XXX secStg Dn Delay=XXX secIce Delay=XXh XXm VIEW UNIT STATUS (4)D.O. 111111111123456789012345678000000000000000000This menu gives the status of digital outputs (D.O.), 1=ON, 0=OFF. Numbers are 1 through 18. See Table 23 on page 49 for number reference.

VIEW UNIT STATUS (5)D.I. 111111111123456789012345678000000000000000000This menu gives the status of digital inputs (D.I.), 1=ON, 0=OFF. Numbers are 1 through 18. See Table 22 on page 49 for number reference.

Water Cooled = Y Water Cooled = N VIEW UNIT TEMP (1) VIEW UNIT TEMP (1)Evap LWT = XX.X°°°°F Evap LWT = XX.X°°°°FCond EWT = XXX.X°°°°F OAT = XXX.X°°°°FLWT Target = XX.X°°°°F LWT Target = XX.X°°°°FThe difference between the two screens above is that water-cooled units will give the entering condenser water temperature and air-cooled units will give the outside air temperature (OAT). The outside-air temperature sensor is furnished with the unit, inside the control panel, wired to the correct terminals. It must be installed outdoors in a location that will give the true outdoor temperature that the condenser coils will see. Splicing of the sensor lead may be required. The unit will not operate without the sensor installed. VIEW UNIT TEMP (2)LWT Pulldn= XX.X °°°°FControl Band= XX.X°°°°F

VIEW CIRCUIT#1 (1)OFF


VIEW CIRCUIT#1 (2)Comp 1 = OFFHours = XXXXXStarts = XXXXX

VIEW CIRCUITt#1 (3)Comp 3 = OFFHours = XXXXXStarts = XXXXX

VIEW CIRCUIT#2 (1)Off

VIEW CIRCUIT#2 (2)Comp 2 = OFFHours = XXXXXStarts = XXXXX

VIEW CIRCUIT#2 (3)Comp 4 = OFFHours = XXXXXStarts = XXXXX VIEW REFRG Cir 1 (1)

psi °°°°FSat Evap XXX.X XX.XSat Cond XXX.X XX.X

VIEW REFRG Cir 1 (2)SuctionTemp=XXX.X°°°°FSurperheat = XXX.X°°°°FEvapApproach= XX.X°°°°F VIEW REFRG Cir 2 (1)

psi °°°°FSat Evap XXX.X XX.XSat Cond XXX.X XX.X

VIEW REFRG Cir 2 (2)SuctionTemp=XXX.X°°°°FSurperheat = XXX.X°°°°FEvapApproach= XX.X°°°°F


Water Cooled = N Only VIEW FANSCircuit#1 ON = 1 of 4Circuit#2 ON = 1 of 4

This screen shows the number of air-cooled condenser fans "on" for each circuit. This screen will show the fans "on" whether they are actually connected to and controlled by the MicroTech II controller or not.

Water Cooled = Y Only VIEW TOWER (1)Stages ON = 1 of 2EntCondTemp = XXX °°°°F

Setpoint = XXX °°°°FThe first Stages ON value is the number of fan stages ON. The second number is the Tower Stages setpoint (0 if Tower Control = None). This screen shows the number of tower fans "on" for each circuit. This screen will show the fans "on" whether they are actually connected to and controlled by the MicroTech II controller or not.

Water Cooled = Y Only VIEW TOWER (2)Bypass Valve = XXX%VFD Speed = XXX%

The Bypass Valve value shall be “None” (in place of XXX%) if the Valve/VFD Control setpoint = None or VFD Stage. The VFD Speed value shall be “None” if the Valve/VFD Control setpoint = None, Valve Setpoint, or Valve Stage.

Screen Definitions – ALARM ALARM ACTIVE (1)Alarm Descriptionhh:mm:ss dd/mmm/yyyy

OR

ALARM ACTIVE (X)No more alarmsPress ENTER to clearall active alarmsIf the unit is off on a shutdown alarm or running, but in a limit alarm condition, the cause and date will appear in the upper screen. If there is a simultaneous occurrence of more than one alarm, the others will appear in additional screens below the first one, accessed by the DOWN ARROW. Either type alarm will light a red light in back of the LEFT-ARROW KEY. The light will go out when the fault is cleared. To clear the fault, scroll down to the last screen and press ENTER. If other faults have appeared, they will all be cleared at the same time.


ALARM LOG (1)Alarm Descriptionhh:mm:ss dd/mmm/yyyyDataThe last 25 alarms, either shutdown or limit, are shown in this menu and subsequent menus located under it. ARROW DOWN from this menu will go to the next-to-last alarm, ARROW DOWN again will go to the second from last, and so on through the last 25 occurrences. The screens are numbered (1), (2), (3), etc.

Screen Definitions – SET

Set Unit Setpoints

SET UNIT SPs (1)Unit Enable = OFFUnit Mode = COOLSource = KEYPADUnit Enable settings can be OFF and ON as determined from the Unit Enable setpoint.

Unit Enable is an external signal or a keypad setting that keeps the unit off when the setting is OFF and allows it to run if there is a call for cooling when the setting is ON. The source for the signal is selected in the 4th line and can be:

1. KEYPAD, in which case the selection is made in line 2 and would be normally selected as ON. This is the normal setting when no external signals are controlling the unit.

2. SWITCHES, in which an external switch is wired across terminals #25 and #35. (See wiring diagram page 39 or 40.)

3. NETWORK, used with BAS signal, which is wired to the three communication ports.

Unit Mode settings can be

1. COOL, normal setting used with chilled water air-condition applications.

2. COOL w/GLYCOL, used with low temperature, glycol applications. It allows a lower LWT setpoint to be used.

3. ICE w/GLYCOL, used with ice storage systems, allows changing from chilled glycol operation to lower temperature ICE operation. In ICE, the unit runs at full load until the ICE setpoint is reached, at which time the unit shuts off. A three-position switch wired to terminals #28 and #38 initiates the change from glycol cooling to making ice. (See wiring diagrams on page 39 or 40.)

Unit Mode settings can be COOL COOLw/Glycol, or ICEw/Glycol, as determined from the Unit Mode setpoint.

Source settings can be KEYPAD, SWITCHES, or NETWORK as determined from the Mode Source setpoint.

SET UNIT SPs (2)Available Modes

=COOL w/GlycolSet w/Unit Switch Off


SET UNIT SPs (3)Evap LWT = XX.X°°°°FIce LWT = XX.X°°°°FEvapDeltaT= XX.X°°°°F SET UNIT SPs (4)Start Delta= XX.X°°°°F

Stop Delta= XX.X°°°°F

See page 45 for an explanation of compressor staging.

SET UNIT SPs (5)Max Pulldn=x.x°°°°F/minEvap Recirc=XXX secLowAmbLock=XX.X°°°°F

SET UNIT SPs (6)Demand Limit=OffWater cooled=Off

Water Cooled = On is the setting for units with on-board water-cooled condensers. WaterCooled = OFF is used for units with remote condensers, usually air-cooled.

SET UNIT SPs (7)Ice Time Delay=XxsecClear Ice Delay=No

SET UNIT SPs (8)CLOCK

dd/mmm/yyyyhh:mm:ss

SET UNIT SPs (9)Units = °°°°F/psiLang = ENGLISH Lang (Language) setting is ENGLISH.


SET UNIT SPs (10)Protocol = NONEIdent Number=001 Baud Rate=9600 BAS interface settings, available mid-2003.

SET UNIT SPs (11)Evap Press SensorCir 1 Cir 2 Offset00.0 00.0 (psi)

The pressure offsets on menus 8 and 9 and the temperature offsets on menus 10, 11 and 12 correct the controller's display of the parameters. The sensors used in these units have a high degree of repeatability but may need correction (offset). An accurate pressure gauge or thermometer is used to determine the correct temperature or pressure. A positive or negative offset value is then entered to make the controller reading agree with the measured value.

SET UNIT SPs (12)Cond Press SensorCir 1 Cir 2 Offset00.0 00.0 (psi)

SET UNIT SPs (13)Leaving EvaporatorWater Temp Sensor Offset= 00.0oF SET UNIT SPs (14)OAT/Cond Lvg WaterTemperature Sensor Offset= 00.0oF SET UNIT SPs (15)Suction Temp SensorCir 1 Cir 2 Offset00.0 00.0 (oF)

SET UNIT SPs (16)ENTER PASSWORD: XXXXActive PasswordLevel: None

Two four-digit passwords provide OPERATOR and MANAGER levels of access to changeable parameters. The passwords are preprogrammed into the controller. Either password must be entered using the ENTER PASSWORD (12) screen before a protected setting can be changed. The operator password is 0100. The manager level is 2001.


This screen can be accessed either through the SET OTHER menu or by simply pressing the ENTER key while on one of the SET screens. The controller will automatically go from the screen with the setting change to this screen. After the correct password has been entered, the controller will automatically return to the original set screen. Once a password has been entered, it remains valid for 15 minutes after the last key-press.

Set Compressor Setpoints

SET COMP SPs k,(1)Clear Cycle Tmr=NoStop-Start =XXminStart-Start =XXminThis menu sets the anti-recycle timers. Stop-Start is the time required before starting a compressor after it has stopped. Start-Start is the time required before starting a compressor after the last time it has started. It is recommended that the default values of 5 minutes and 15 minutes not be changed. Clear Cycle Tmr overrides the anti-recycle timers and should only be used for service testing and not for normal unit operation. SET COMP SPs (2)InterStgUp =XXXsecInterStgDown= XXsec

InterStageUp is the time delay since the last stage change before a compressor can stage on, default is 120 sec. InterStageDn is the time delay since the last stage change before a compressor can stage off normally (not by an alarm). Default is 30 sec. It is recommended that these settings not be changed. SET ALARM LMTS (1)LowEvPrHold=XXXpsiLowEvPrUnld=XXXpsiLowEvPrStop=XXXpsiThe LowEvPrHold and LowEvPrUnld have the same default value of 59 psi. If two compressors are running, the LowEvPrUnld is in effect and the lag compressor will be shut off to unload the unit. If one compressor is running, the LowEvPrHold is in effect and the lag compressor is prevented from starting, thereby holding the unit capacity. The last action to take place is the shutoff of all compressors running when the LowEvPrStop setting is reached (default is 58 psi). Reducing these time intervals will increase detrimental compressor cycling. It is recommended that these settings not be changed. SET ALARM LMTS (2)LowEvpPrDelay=XXsEvap Freeze= XX.X°°°°FEvapFlowProof=XXXsecEvap Freeze (the unit freeze protection shutdown) is actually a stop alarm and shuts off the unit when the LWT reaches 36°F. It is cleared by going to the CLEAR ALARM menu in the ACTIVE ALARM hierarchy. LowEvPrDelay is a time delay on the low pressure trip that reduces nuisance low-pressure trips. The default setting is 30 seconds. EvapFlowProof is the flow switch interlock. Closing the flow switch and therefore proving the existence of chilled water flow resets this trip. It is recommended that these settings not be changed.


SET ALARM LMTS (3)HiCondPr =XXX.XpsiHiPrStgDn=XXX.XpsiCondFreeze=xx.x°°°°FHighCondPr (the unit high-discharge-pressure shutdown) is a stop alarm that shuts off the unit when the discharge pressure reaches the setting. The default setting is 380 psi.

The HiCondStgDn is a limit alarm that unloads the unit at 370 psi in an attempt to prevent total shutdown from the HighCondPr at 380 psi. The stage down is set at 370 psi. It is recommended that these settings not be changed.

CondFreeze is an alarm that reduces the chance of freezing the water in the condenser (when compressors are not running). An alarm is registered and the condenser pump is energized at the same time. The alarm setpoint is 34°F saturated condenser temperature and it resets at +2°F above the setpoint.

SET ALARM LMTS (4)GroundFault = NPhaseVoltage = NLowAmbLock= XX °°°°FGroundFault and PhaseVoltage entries are Y (Yes) or N (No) depending on whether the options are on the unit.

LowAmbientLock applies to units with air-cooled condensers and prevents unit operation below the setting. The available range is -2°F to 60°F with a default of 35°F.

Set Air-Cooled Condenser Fans SET FANS SPs (1)Fan Stages=XSpeedtrol=Yes/No

SET FANS SPs (2)Stage ON psi#1/2 #3/4XXXX XXXX

SET FANS SPs (3)Stage ON psi#5/6 #7/8XXXX XXXX SET FANS SPs (4)Stage Off psi#1/2 #3/4XXXX XXXX


SET FANS SPs (5)Stage Off psi#5/6 #7/8XXXX XXXX

The SET FANS SP screens 2 through 5 establish the discharge pressures that will stage the condenser fans on and off. These screens apply only to units set up for use with air-cooled condensers (WaterCooled=No). On such units, the settings do not have to be entered if the unit controller is not used to stage condenser fans for head pressure control. If the MicroTech II unit controller is not used to control the fans, some other method must be used.

Set Cooling Tower Control The MicroTech II controller is capable of controlling cooling tower water temperature on chillers using water-cooled condensers. Output wiring connection points are shown on the field wiring diagrams.

[Water Cooled = Y] - Condenser Pump on with first Compressor on. Tower fan control is active when the Tower Control setpoint is set to Temperature and the condenser pump is in the RUN state. Staging is based on Entering Condenser Water Temperature (ECWT). Operation depends on the following parameters. • Condenser pump state • ECWT OR Lift pressure • Stage up and stage down timer values • Tower setpoints (Tower Control, Tower Stages, Stage Up Time, Stage Down Time, Stage

Differential, Stage #1 ON, Stage #2 ON, Stage Down @, Stage Up @) When the condenser pump starts, the stage up timer shall start. The first stage shall turn ON when the following conditions are met: • The stage up timer completes • The ECWT is > Stage #1 ON setpoint • Bypass valve position is > the Stage Up @ setpoint (only if Valve/VFD Control setpoint = Valve

Stage) Additional stages can turn on (up to the number specified by the Tower Stages setpoint) when above conditions are met for the next stage plus the following condition: • VFD Speed is > the Stage Up @ setpoint (only if Valve/VFD Control setpoint = VFD Stage OR

Valve SP/VFD Stage) Down staging shall occur when the following conditions are met: • The stage down timer completes • The ECWT is < Stage #X ON (Temp) setpoint – Stage Differential (Temp) setpoint point • Bypass valve position is < the Stage Down @ setpoint (only if Valve/VFD Control setpoint =

Valve Stage) • VFD Speed is < the Stage Down @ setpoint (only if Valve/VFD Control setpoint = VFD Stage

OR Valve SP/VFD Stage) Each stage up or stage down event shall restart both the stage up and stage down timers. Only one fan output shall be switched at a time (except that all outputs switch OFF when the condenser pump state equals OFF).


SET TOWER SPs (1)Tower Control= NoneTower Stages = XStageUP/DN=XXX/XXX%When Tower Control is None the control of condenser water temperature is not by the MicroTech II controller and assumed to be furnished elsewhere.

Tower Stages is the number of tower fans to be staged by the controller, choices are 0, 1, or 2. "0" indicates control will be by a bypass valve or variable speed pump controlled by the MicroTech II controller.

StageUP/DN imposes a time delay between fan stages when turning on or turning off.

SET TOWER SPs (2)Stage ON (Temp)°°°°F

#1 #2XXX XXX

Stage ON Temp is the entering condenser water temperature (ECWT) that will turn on tower fan #1 and #2. Default settings are 70°F and 75°F. Cold condenser water will improve unit efficiency but too cold can cause erratic operation. Settings below 60°F are not recommended.

SET TOWER SPs (3)StageDiff = XX.X°°°°FStage Up = XX minStageDown = XX minStageDiff is the number of degrees below the Stage ON that will turn off the tower fans. For example, if Stage ON #1 is 70°F and StageDiff is 5°F, tower fan #1 will stage off when the ECWT drops to 65°F and stage the fan on when the ECWT rises to 70°F. The same is true for fan #2.

Stage Up timer is the number of minutes that must elapse between the condenser pump starting (it starts with the unit) and fan #1 starting or the time between fan #1 starting and fan #2 starting.

StageDown is the elapsed time between staging down the fan motors.

SET TOWER SPs (4)Valve/VFD Control=

ValveSP/VFDStageValve Type = NCValve/VFD Control settings are None, Valve Setpoint, Valve Stage, VFD Stage, or ValveSP/VFDStage. Default is None which results in no control of the tower from the MicroTech II controller.

• Valve Setpoint, the valve will control (bypass tower) to hold the minimum temperature as established by the Set Tower SPs in screen (5) below.

This mode is operational when the Valve/VFD Control setpoint is set to Valve Setpoint OR Valve SP/VFD Stage. In this mode the valve output is varied with a proportional-derivative (PD) algorithm (with deadband) in order to maintain the controlled parameter (CP) at the desired value. The output is always limited between the Valve Control Range (Min) setpoint and the Valve Control Range (Max) setpoint. A valve increment shall be computed once every 5 seconds according to the following equation. (Error Gain and Slope Gain are set in menu screen #8.)


Increment = [(Error) * (Error Gain setpoint)] + [(Slope) * (Slope Gain setpoint)] Where: Error = ECWT – Valve Setpoint Slope = (Present CP) – (Previous CP)

When the Error is > the Valve Deadband setpoint, the valve position analog output (% of full scale) is updated according to the following equation.

New %Position = Old %Position + Increment/10

• Valve Stage, controls from the fan stage setpoint in use. It is recommended that the Valve Setpoint method explained above be used rather than this mode.

This mode is only operational when the Valve/VFD Control setpoint is set to Valve Stage. In this mode the valve output is controlled as for Valve Setpoint mode (above), except that the active setpoint for the controlled parameter is selected according to the following table.

# Of Fans ON Active Setpoint 0 Valve Setpoint 1 Stage #1 ON 2 Stage #2 ON 3 Stage #3 ON 4 Stage #4 ON

• VFD Stage, ValveSP/VFDStage, When the Valve/VFD Control setpoint is set to None, Valve Setpoint, OR Valve Stage, this output is set to 0. Otherwise, it will be controlled in a manner identical to Valve Stage Mode (above) except that (1) it shall be kept at zero until the first fan stage is ON, and (2) the following setpoints do not apply.

Valve Control Range (Min) Valve Control Range (Max) Valve Type

Valve Type settings are NC (normally closed to tower) or NO (normally open). These settings establish the operation of a tower bypass valve (must be a 3-way valve).

Initial Valve Position When the condenser pump is not in the RUN state, the valve output shall be set as a function of entering condenser water temperature (ECWT) per the following graph.

Figure 26, Initial Valve Position

Max Position @Setpoint

(90°F)

Min Position @

(60°F)

Min Start Position(10%)

Initial Valve Position(values are examples only)

Max Start Position(90%)

Setpoint

Setpoint Setpoint


Operation After Start When the condenser pump is in the RUN state, the valve output shall be controlled in one of two modes as specified by the Valve/VFD Control setpoint. The controlled parameter shall be the condenser entering water temperature. When the desired output signal varies from 0 to 100%, the output voltage shall vary as shown below.

0 to 10 VDC (Valve Type = NC)

10 to 0 VDC (Valve Type = NO)

SET TOWER SPs (5)Valve SP = XXX °°°°FValve DB = XX.X °°°°F

Valve SP is the minimum tower water temperature acceptable, default is 65°F.

Valve DB is the dead-band in degrees, default is 2.0°F.

SET TOWER SPs (6)ValveStartPositionMin = XXX% @XXX°°°°FMax = XXX% @XXX°°°°F

The ValveStartposition is the position of the valve when the unit starts. Default for minimum start position is 0%, and 100% for maximum position.

SET TOWER SPs (7)Valve Control Range

Min = XXX%Max = XXX%

Defaults are 10% minimum and 90% maximum.

SET TOWER SPs (8)PD Control Loop

Error Gain = XXSlope Gain = XX

Defaults are 25 for both error and slope.

Editing Review Editing shall be accomplished by pressing the ENTER key until the desired field is selected. This field shall be indicated by a blinking cursor under it. The arrow keys shall then operate as defined below.

CANCEL (Right) Reset the current field to the value it had when editing began. DEFAULT (Left) Set value to original factory setting. INCREMENT (Up) Increase the value or select the next item in a list. DECREMENT (Down) Decrease the value or select the previous item in a list. During edit mode, the display shall show a two-character wide menu pane on the right as shown below.


SET UNIT SPs (X) <D(data) <C(data) <+(data) <-

Additional fields can be edited by pressing the ENTER key until the desired field is selected. When the last field is selected, pressing the ENTER key switches the display out of “edit” mode and returns the arrow keys to “scroll” mode.

Alarms When an alarm occurs, the alarm type, limit value (if any), date, and time are stored in the active alarm buffer corresponding to that alarm (viewed on the Alarm Active screens) and also in the alarm history buffer (viewed on the Alarm Log screens). The active alarm buffers hold a record of the last occurrence of each alarm and whether or not it has been cleared. The alarm can be cleared by pressing the Edit key. A separate buffer is available for each alarm (High Cond Pressure, Evaporator Freeze Protect, etc.). The alarm history buffer holds a chronological account of the last 25 alarms of any type.

Security Two four-digit passwords provide OPERATOR and MANAGER levels of access to changeable parameters. Either password can be entered using the ENTER PASSWORD screen which can be accessed either through the SET OTHER menu or by simply pressing the ENTER key while on one of the SET screens. The password can then be entered by pressing the ENTER key, scrolling to the correct value with the UP and DOWN arrow keys, and pressing ENTER again. Once the correct password has been entered, the previously selected screen will reappear. Once a password has been entered, it will remain valid for 15 minutes after the last key-press.

BAS Interface The MicroTech II controller is equipped with the Protocol Selectability feature, an exclusive McQuay feature that provides easy unit interface with a building automation system. If the unit will be tied into a BAS, the controller should have been purchased with the correct factory-installed interface module. The modules can also be added in the field during or after installation.

If an interface module was ordered, one of the following BAS interface installation manuals was shipped with the unit. Contact your local McQuay sales office for a replacement, if necessary.

• IM 735, LONWORKS Communication Module Installation

• IM 736, BACnet Communication Module Installation


Optional Controls

Phase/Voltage Monitor (Optional) The phase/voltage monitor is a device that provides protection against three-phase electrical motor loss due to power failure conditions, phase loss, and phase reversal. Whenever any of these conditions occur, an input relay is deactivated, disconnecting power to the thermostatic control circuit. The compressor do a rapid shutdown pump down.

The input relay remains deactivated until power line conditions return to an acceptable level. Trip and reset delays have been provided to prevent nuisance tripping due to rapid power fluctuations.

When three-phase power has been applied, the input relay should close and the “run light” should come on. If the relay does not close, perform the following tests.

1. Check the voltages between L1-L2, L1-L3, and L2-L3. These voltages should be approximately equal and within +10% of the rated three-phase line-to-line voltage.

2. If these voltages are extremely low or widely unbalanced, check the power system to determine the cause of the problem.

3. If the voltages are good, turn off the power and inter-change any two of the supply power leads at the disconnect switch.

This may be necessary, as the phase/voltage monitor is sensitive to phase reversal. Turn on the power. The relay should now close after the appropriate delay.

Factory settings are as follows: Voltage Setting, set at nameplate voltage. Trip Delay Time, 2 seconds Restart Delay Time, 60 seconds

Hot Gas Bypass (Optional) This option allows passage of discharge gas to the evaporator, permitting operation at lower loads than available with compressor unloading. It also keeps the velocity of refrigerant gas high enough for proper oil return at light load conditions.

The pressure regulating valve is a Sporlan SHGBE-8 and factory set to begin opening at 69 psig and can be changed by changing the pressure setting. The adjustment range is 0 to 100 psig. To raise the pressure setting, remove the cap on the bulb and turn the adjustment screw clockwise. To lower the setting, turn the screw counterclockwise. Do not force the adjustment beyond the range it is designed for, as this will damage the adjustment assembly. The regulating valve opening point can be determined by slowly reducing the system load while observing the suction pressure. When the bypass valve starts to open, the refrigerant line on the evaporator side of the valve will begin to feel warm to the touch.

WARNING The hot gas line can become hot enough to cause personal injury in a very short

time; care should be taken during valve checkout.


System Maintenance

General To provide smooth operation at peak capacity and to avoid damage to package components, a program of periodic inspections should be set up and followed. The following items are intended as a guide to be used during inspection and must be combined with sound refrigeration and electrical practices to provide trouble-free performance.

The liquid line sight glass/moisture indicator on all circuits must be checked to be sure that the glass is full and clear and that the moisture indicator indicates a dry condition. If the indicator shows that a wet condition exists or if bubbles show in the glass, even with a full refrigerant charge, the filter-drier element must be changed.

Water supplies in some areas can tend to foul the water-cooled condenser to the point where cleaning is necessary. The fouled condenser will be indicated by an abnormally high condenser approach temperature (saturated discharge temperature minus leaving condenser water temperature) and can result in nuisance trip-outs. To clean the condenser, mechanical cleaning or a chemical descaling solution should be used according to the manufacturer’s directions.

Systems with remote air-cooled condensers require periodic cleaning of the finned surface of the condenser coil.

Cleaning can be accomplished by using a cold water spray, brushing, vacuuming, or high-pressure air. No tools should be used that could damage the coil tubes or fins.

The compressor oil level must be checked periodically to be sure that the level is at the center of the oil sightglass located in the compressor's equalizing line or on the compressor itself. Low oil level can cause inadequate lubrication and if oil must be added, use oils referred to in the following “Compressor Lubrication” section.

A pressure tap has been provided on the liquid line downstream of the filter-drier and solenoid valve but before the expansion valve. An accurate subcooled liquid pressure and temperature can be taken here. The pressure read here could also provide an indication of excessive pressure drop through the filter-drier and solenoid valve due to a clogging filter-drier. Note: A normal pressure drop through the solenoid valve is approximately 3 psig (20.7 kPa) at full load conditions.

CAUTION

Warranty may be affected if wiring is not in accordance with specifications. A blown fuse or tripped protector indicates a short ground or overload. Before replacing fuse or restarting compressor, the trouble must be found and corrected. It is important to have a qualified control panel electrician service this panel. Unqualified tampering with the controls can cause serious damage to equipment and void the warranty.

DANGER

The panel is always energized to ground even when the system switch is off. To de-energize the complete panel including crankcase heaters, pull the main unit

disconnect. Failure to do so can result in severe personal injury or death.

If motor or compressor damage is suspected, do not restart until qualified service personnel have checked the unit.


Electrical Terminals

WARNING To avoid injury from electric shock hazard, turn off all power and perform lockout and

tag-out of source before continuing with the following service. Note that the unit might be powered from multiple sources.

All power electrical terminals should be re-tightened every six months, as they tend to loosen due to normal heating and cooling of the wire.

Compressor Lubrication The oil level should be watched carefully upon initial start-up and regularly thereafter.

All tandem compressors on WGZ units come equipped with one or two oil equalization lines connecting the crankcase of each set of compressors in each refrigerant circuit. This allows the oil to move from one compressor crankcase to the other during normal operation, and balance between the two when the compressors are off. The oil sight glass is located in the equalization line on one circuit of the WGZ 070 and both circuits of WGZ 080 through WGZ 100. All other models have the oil sight glass in the compressor body. In either case, the oil level should be 1/4 to 1/3 of the glass.

At the present time, standard refrigerant mineral oils such as Suniso No. 3GS, Calumet R015, and Texaco WF32 oils are approved by Copeland for use in these compressors.

Oil can be added to the Copeland compressor through the oil fill hole in the crankcase. Special equipment is required to add oil and the work should be done by qualified refrigeration technicians with the proper training and equipment.

Sight glass and Moisture Indicator The refrigerant sight glasses should be observed periodically. A monthly observation should be adequate. A clear glass of liquid indicates that there is adequate refrigerant charge in the system to provide proper feed through the expansion valve. The sight glass should be clear when:

• Ambient temperature is above 75°F (23°C) • Both compressors on a circuit are running • All fans on a circuit are running

Bubbling refrigerant in the sight glass may occur at other conditions and may indicate that the system is short of refrigerant charge. Refrigerant gas flashing in the sight glass could also indicate an excessive pressure drop in the line, possibly due to a clogged filter-drier or a restriction elsewhere in the system. An element inside the sight glass indicates what moisture condition corresponds to a given element color. If the sight glass does not indicate a dry condition after about 12 hours of operation, the unit should be pumped down and the filter-driers changed.

If the system is suspected of being short of refrigerant, a qualified service technician with EPA certification should be contacted to thoroughly check out the unit and add refrigerant if necessary.

Crankcase Heaters The compressors are equipped with crankcase heaters. The function of the heater is to keep the temperature in the crankcase high enough to prevent refrigerant from migrating to the crankcase and condensing in the oil during off-cycle. When a system is to be started up initially, the power to the heaters should be turned on for at least 12 hours before the compressors are started. The crankcase should be up to about 80°F (26.7°C) before the system is started up, to minimize lubrication problems or liquid slugging of compressor on start-up.

If the crankcase is cool (below 80°F) (26.7°C) and the oil level in the sight glass is full to top, allow more time for oil to warm before starting the compressor.

The crankcase heaters are on whenever power is supplied to the unit and the compressor is not running.


Maintenance Schedule

I. Compressor A. Performance Evaluation (Log & Analysis) * O B. Motor • Meg. Windings X • Ampere Balance (within 10%) X • Terminal Check (tight connections, porcelain clean) X • Motor Cooling (check temperature) X C. Lubrication System • Oil Level O X • Oil Appearance (clear color, quantity) O

• Oil change if indicated by oil analysis X II. Controls A. Operating Controls • Check Settings and Operation X B. Protective Controls • Test Operation of: Alarm Relay X Pump Interlocks X High and Low Pressure Cutouts X III. Condenser B. Test Water Quality X C. Clean Condenser Tubes (or as required) X D. Eddycurrent Test - Tube Wall Thickness X E. Seasonal Protection X IV. Evaporator B. Test Water Quality X C. Clean Evaporator Tubes (or as required) X D. Eddycurrent Test - Tube Wall thickness (or as required) X E. Seasonal Protection X V. Expansion Valves A. Performance Evaluation (Superheat Control) X VI. Compressor - Chiller Unit A. Performance Evaluation O B. Leak Test: • Compressor Fittings and Terminal X • Piping Fittings X • Vessel Relief Valves X C. Vibration Isolation Test X D. General Appearance: • Paint X • Insulation X VII. Starter(s) A. Examine Contactors (hardware and operation) X B. Verify Overload Setting and Trip X C. Test Electrical Connections X VIII. Optional Controls A. Hot Gas Bypass (verify operation) X

Key: O = Performed by in-house personnel X = Performed by service personnel


System Service

DANGER

Service on this equipment is to be performed only by qualified refrigeration personnel. Causes for repeated tripping of equipment protection controls must be

investigated and corrected. Disconnect all power before doing any service inside the unit or serious personal injury or death can occur.

NOTE: Anyone servicing this equipment must comply with the requirements set forth by the EPA concerning refrigerant reclamation and venting.

Filter-Driers To change the filter-drier, pump the unit down (with the compressor running) by closing the manual liquid line shutoff valve(s). The unit will start pumping down until it reaches the low-pressure cutoff setting of 58 psi.

Close the discharge valve. Remove the refrigerant in the liquid line with a recovery unit to EPA required pressure. Remove and replace the filter-drier(s). Evacuate the lines through the liquid line manual shutoff valve(s) to remove noncondensables that may have entered during filter replacement. A leak check is recommend before returning the unit to operation.

Unit Arrangement Unit Size Type Filter-Drier Water-Cooled 030 - 060 Sealed/Brazed Water-Cooled 070 - 100 2-core Replaceable

Remote Condenser All 2-core Replaceable

Liquid Line Solenoid Valve The liquid line solenoid valve(s), which are responsible for automatic pumpdown during normal unit operation, do not normally require any maintenance. However, in the event of failure they can require replacement of the solenoid coil or of the entire valve assembly.

The solenoid coil can be removed from the valve body without opening the refrigerant piping by moving pumpdown switch(es) PS1 and PS2 to the “manual” position.

The coil can then be removed from the valve body by simply removing a nut or snap-ring located at the top of the coil. The coil can then be slipped off its mounting stud for replacement. Be sure to replace the coil on its mounting stud before returning pumpdown switch(es) PS1 and PS2 to the “auto pumpdown” position.

To replace the entire solenoid valve, follow the steps for changing a filter-drier.


Thermostatic Expansion Valve The expansion valve is responsible for allowing the proper amount of refrigerant to enter the evaporator regardless of cooling load. It does this by maintaining a constant superheat. (Superheat is the difference between refrigerant temperature as it leaves the evaporator and the saturation temperature corresponding to the evaporator pressure). All WGZ chillers are factory set for between 8°F and 12°F (4.4°C to 6.7°C) superheat at full load. To increase the superheat setting of the valve, remove the cap at the bottom of the valve to expose the adjustment screw. Turn the screw clockwise (when viewed from the adjustment screw end) to increase the superheat and counterclockwise to reduce superheat. Allow time for system rebalance after each superheat adjustment.

The expansion valve, like the solenoid valve, should not normally require replacement, but if it does, the unit must be pumped down by following the steps involved when changing a filter-drier.

If the problem can be traced to the power element only, it can be unscrewed from the valve body without removing the valve, but only after pumping the unit down.

Figure 27, Thermostatic Expansion Valve

CAUTION

Adjustment of expansion valve should only be performed by a qualified service technician. Failure to do so can result in improper unit operation.

Note: Superheat will vary with compressor unloading, but should be approximately as follows: between 8°F and 12°F (4.4°C and 6.7°C) at full load; between 6°F and 10°F at part load.

Evaporator The evaporator is a sealed, brazed-stainless steel plate unit. Normally no service work is required on the evaporator.

Water-cooled Condenser The condenser is of the shell-and-tube type with water flowing through the tubes and refrigerant in the shell. External finned copper tubes are rolled into steel tube sheets and to the center dividing tube sheet. Integral subcoolers are incorporated on all units. All condensers are equipped with 450 psig (3104 kPa) relief valves. Normal tube cleaning procedures can be followed.


Troubleshooting Chart PROBLEM POSSIBLE CAUSES POSSIBLE CORRECTIVE STEPS

Compressor Will Not Run

1. Main switch, circuit breakers open. 2. Fuse blown. 3. Thermal overloads tripped or fuses

blown. 4. Defective contactor or coil. 5. System shut down by equipment

protection devices. 6. No cooling required. 7. Liquid line solenoid will not open. 8. Motor electrical trouble. 9. Loose wiring.

1. Close switch 2. Check electrical circuits and motor

winding for shorts or grounds. Investigate for possible overloading. Replace fuse or reset breakers after fault is corrected.

3. Overloads are auto reset. Check unit closely when unit comes back on line.

4. Repair or replace. 5. Determine type and cause of shutdown

and correct it before resetting protection switch.

6. None. Wait until unit calls for cooling. 7. Repair or replace coil. 8. Check motor for opens, short circuit, or

burnout. 9. Check all wire junctions. Tighten all

terminal screws.

Compressor Noisy or Vibrating

1. Flooding of refrigerant into crankcase. 2. Improper piping support on suction or

liquid line. 3. Worn compressor.

1. Check superheat setting of expansion valve.

2. Relocate, add or remove hangers. 3. Replace.

High Discharge Pressure

1. Condenser water insufficient or temperature too high.

2. Fouled condenser tubes (water-cooled condenser). Clogged spray nozzles (evaporative condenser). Dirty tube and fin surface (air cooled condenser).

3. Noncondensables in system. 4. System overcharge with refrigerant. 5. Discharge shutoff valve partially closed. 6. Condenser undersized (air-cooled). 7. High ambient conditions.

1. Readjust temperature control or water regulating valve. Investigate ways to increase water supply.

2. Clean.

3. EPA purge the noncondensables. 4. Remove excess refrigerant. 5. Open valve. 6. Check condenser rating tables against

the operation. 7. Check condenser rating tables against

the operation.

Low Discharge Pressure

1. Faultly condenser temp. regulation. 2. Insufficient refrigerant in system. 3. Low suction pressure. 4. Condenser too large. 5. Low ambient conditions.

1. Check condenser control operation. 2. Check for leaks. Repair and add charge. 3. See corrective steps for low suction

pressure below. 4. Check condenser rating table against the

operation. 5. Check condenser rating tables against

the operation.

High Suction Pressure

1. Excessive load. 2. Expansion valve overfeeding.

1. Reduce load or add additional equipment.

2. Check remote bulb. Regulate superheat.

Low Suction Pressure

1. Lack of refrigerant. 2. Evaporator dirty. 3. Clogged liquid line filter-drier. 4. Clogged suction line or compressor

suction gas strainers. 5. Expansion valve malfunctioning. 6. Condensing temperature too low. 7. Compressor will not unload. 8. Insufficient water flow.

1. Check for leaks. Repair and add charge. 2. Clean chemically. 3. Replace cartridge(s). 4. Clean strainers. 5. Check and reset for proper superheat.

Replace if necessary. 6. Check means for regulating condensing

temperature. 7. See corrective steps for failure of

compressor to unload. 8. Adjust flow.

Little or No Oil Pressure

1. Clogged suction oil strainer. 2. Excessive liquid in crankcase. 3. Low oil level. 4. Flooding of refrigerant into crankcase.

1. Clean. 2. Check crankcase heater. Reset

expansion valve for higher superheat. Check liquid line solenoid valve operation.

3. Add oil. 4. Adjust thermal expansion valve.


PROBLEM POSSIBLE CAUSES POSSIBLE CORRECTIVE STEPS

Compressor Loses Oil

1. Lack of refrigerant. 2. Velocity in risers too low (A-C only). 3. Oil trapped in line.

1. Check for leaks and repair. Add refrigerant.

2. Check riser sizes. 3. Check pitch of lines and refrigerant

velocities.

Motor Overload Relays or Circuit Breakers Open

1. Low voltage during high load conditions. 2. Defective or grounded wiring in motor or

power circuits. 3. Loose power wiring. 4. High condensing temperature. 5. Power line fault causing unbalanced

voltage. 6. High ambient temperature around the

overload relay

1. Check supply voltage for excessive line drop.

2. Replace compressor-motor. 3. Check all connections and tighten. 4. See corrective steps for high discharge

pressure. 5. Check Supply voltage. Notify power

company. Do not start until fault is corrected.

6. Provide ventilation to reduce heat.

Compressor Thermal Switch Open

1. Operating beyond design conditions. 2. Discharge valve partially shut.

1. Add facilities so that conditions are within allowable limits.

2. Open valve.

Freeze Protection Opens

1. Thermostat set too low. 2. Low water flow. 3. Low suction pressure.

1. Reset to 42°F (6°C) or above. 2. Adjust flow. 3. See “Low Suction Pressure.”

Warranty Statement

Limited 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.


Post Office 2510, Staunton, Virginia 24402 USA • (800) 432-1342 • www.mcquay.com IOMM WGZ-1 (10/04)

Documents

Water-Cooled Scroll Compressor Chillers › api › sharepoint › get...driers, liquid line solenoid valves, sight glass/moisture indicators, and thermal expansion valves. Other features