WPV Centrifugal Compressor Chillers -...

Installation, Operating and Maintenance Manual IOMM WPV

Group: Chiller Part Number: 736015421 Effective: October 2005 Supersedes: New

WPV Centrifugal Compressor Chillers

WPV 240 to 430 220 tons to 430 tons (770 kW to 1500 kW)

2 Centrifugal Chillers IOMM WPV

Table of Contents Introduction ............................................................................................................... 3

General Description........................................................................................................................... 3 Application ........................................................................................................................................ 3

Installation ................................................................................................................. 4 Receiving and Handling .................................................................................................................... 4 Location and Mounting ..................................................................................................................... 4 Location and Mounting ..................................................................................................................... 5 Water Piping ...................................................................................................................................... 5 System Water Volume........................................................................................................................ 7 Physical Data and Weights ................................................................................................................ 7 Evaporator ......................................................................................................................................... 7 Condenser.......................................................................................................................................... 8 Oil Coolers ........................................................................................................................................ 8 Refrigerant Vent Piping ................................................................................................................... 10 Electrical.......................................................................................................................................... 11 Power Wiring................................................................................................................................... 11 Control Wiring................................................................................................................................. 12 Prestart System Checklist ................................................................................................................ 14

Operation ................................................................................................................. 15 Operator Responsibilities ................................................................................................................ 15 Standby Power................................................................................................................................. 15 Nomenclature .................................................................................................................................. 15 Operating Limits.............................................................................................................................. 15 MicroTech II Control....................................................................................................................... 16 Capacity Control System ................................................................................................................. 16 Lubrication System.......................................................................................................................... 18

Pressure Drops......................................................................................................... 20

Dimensions ............................................................................................................... 22 WPV Chillers .................................................................................................................................. 22

Maintenance............................................................................................................. 26 R-134a Pressure/Temperature Chart................................................................................................ 26 Routine Maintenance....................................................................................................................... 26 Annual Shutdown ............................................................................................................................ 29 Annual Startup................................................................................................................................. 29 Repair of System ............................................................................................................................. 30

Maintenance Schedule ............................................................................................ 32

Service Programs..................................................................................................... 34

Operator Schools ..................................................................................................... 34

McQuay" is a registered trademark of McQuay International ©2002 McQuay International

"Information and illustrations cover the McQuay International product at the time of publication and we reserve the right to make changes in design and construction at anytime without notice".

IOMM WPV Centrifugal Chillers 3

Introduction

General Description The McQuay WPV Centrifugal Water Chillers are complete, self-contained, automatically controlled fluid chilling units. Each unit is completely assembled and factory tested before shipment.

In the WPV series, each unit has one compressor connected to a condenser and evaporator and is equipped with a factory-mounted starter.

The chillers use refrigerant R-134a to reduce the size and weight of the package compared to negative pressure refrigerants and since R-134a operates at a positive pressure over the entire operation range, no purge system is required.

The controls are pre-wired, adjusted and tested. Only normal field connections such as piping, electrical and pump interlocks, etc. are required thereby simplifying installation and increasing reliability. All necessary equipment protection and operating controls (except flow switches) are factory installed in the control panel.

The sizes of units are the WPV 240, 280, 290, 320 350, 390, 410, and 430 providing a capacity range from 220 tons to 430 tons.

Application The operation and maintenance procedures presented in this manual apply to the standard WPV family of chillers. Refer to the Operating Manual, OM CentrifMicro II (latest version) for details pertaining to operation of the MicroTech II� control.

All McQuay centrifugal chillers are factory tested prior to shipment and must be initially started at the job site by a factory trained McQuay service technician. Failure to follow this startup procedure will affect the equipment warranty.

The standard warranty on this equipment covers parts that prove defective in material or workmanship and the labor to replace them. Specific details of this warranty can be found in the warranty statement furnished with the equipment. Refrigerant are not included unless specifically ordered as an option.

Cooling towers used with McQuay centrifugal chillers are normally selected for maximum condenser inlet water temperatures between 75°F and 90°F (24°C and 32°C). Lower entering water temperatures are desirable from the standpoint of energy reduction but a minimum does exist. For recommendations for optimum entering water temperature and cooling tower fan control, consult McQuay Product Manual PM WPV, Applications Section.


Installation

Receiving and Handling The unit should be inspected immediately after receipt for possible damage.

All McQuay centrifugal water chillers are shipped FOB factory and all claims for handling and shipping damage are the responsibility of the consignee.

Insulation on the upper corners of the evaporator at the rigging holes is shipped loose and should be glued in place after the unit is finally placed. Neoprene vibration pads are also shipped loose. Check to be sure that these items are delivered with the unit.

The units are shipped without skids and means for rolling/sliding units must be supplied in the field.

Extreme care should be used when rigging the equipment to prevent damage to the control center, or refrigerant piping. See certified dimension sheets for the center of gravity of the unit.

The unit can be lifted by fastening the rigging hooks to the four outside corners of the unit where the rigging eyes are located (see Figure 1). Spreader bars should be used between the rigging lines to prevent damage.

Figure 1, Unit Components

Unit Control Panel

Rigging Locations 4 Each End

Operator Interface Panel

Motor Starter

Evaporator

Condenser


Location and Mounting Clearance The unit should be mounted on a level concrete or steel base and should be located so as to provide service clearance at one end of the unit for possible removal of evaporator tubes and/or condenser tubes. Tube clearances required are 14 feet (4.3 meters) for units with 12-foot (3.7 meters) long shells, and 11 feet (3.3 meters) for units with 9-foot (2.7meters) long shells. Evaporator/condenser tubes are rolled into the tube sheets to permit replacement if necessary. Clearance at all other points, including the top, is 3 feet (1 meter).

Vibration Pads The shipped loose neoprene vibration pads should be located under the corners of the unit (unless the job specifications state otherwise). They are installed to be flush with the sides and outside edge of the feet. Some WPV units have six mounting feet although only the outer four are required. Six pads are shipped and the installer can place pads under the middle feet if desired.

Mounting Make sure that the floor or structural support is adequate to support the full operating weight of the complete unit.

It will not be necessary to bolt the unit to the mounting slab or framework; but should this be desirable, 1 1/8" (28.5 mm) mounting holes are provided in the unit support at the four corners.

Note: Units are shipped with refrigerant and oil valves closed to isolate these fluids for shipment. Valves must remain closed until start-up by McQuay technician.

Water Piping Vessel Drains at Start-up The unit is tilted and drained of water in the factory and shipped with open drain valves in each head. .Be sure to close the valves prior to filling the vessel with fluid.

Water Pumps

Note: Avoid the use of 3600/3000 rpm (two-pole motor) pump motors.

It is not uncommon to find that these pumps operate with objectionable noise and vibration.

It is also possible to build up a frequency beat due to the slight difference in the operating rpm of the pump motor and the McQuay centrifugal motor. McQuay encourages the use of 1750/1460 rpm or four-pole pump motors whenever possible.

Evaporator and Condenser Water Piping All WPV evaporators and condensers come standard with groove-type nozzles for Victaulic couplings (also suitable for welding) or optional flange connections. The installing contractor must provide matching mechanical connections of the sizes given in the system dimension and capacity tables.

Important Notes on Welding 1. If welding is to be performed on the mechanical or flange connections, the solid-state

temperature sensor and thermostat bulbs must be removed from the wells to prevent damage to those components.

2. The unit must be properly grounded or severe damage to the MicroTech II controller can occur.

Small water pressure test valves or pipe plugs are provided at both the inlets and outlets of the vessel heads. The test valves permit the water flow pressure drops to be checked. The pressure drops and flow rates for the various evaporators and condensers are shown on pressure drop curves contained in this manual. Refer to the nameplate on the vessel shell for identification.

Be sure that water inlet and outlet connections match certified drawings and stenciled nozzle markings.


• The condenser is connected with the coolest water entering at the bottom to maximize subcooling.

• The evaporator inlet is always on the left when looking at the nozzles from the connection end.

CAUTION

When common piping is used in connection with a heating system, care should be taken to insure that water flowing through the evaporator cannot exceed 110°F which can cause the relief valve to discharge refrigerant or damage controls.

The piping should be supported to reduce the weight and strain on the fittings and connections. Piping should also be adequately insulated. A cleanable 20-mesh water strainer should be installed at both inlets. Sufficient shutoff valves should be installed to permit draining the water from the evaporator or condenser without draining the complete system.

Flow Switch A water flow switch must be mounted in the leaving water line of the evaporator and condenser to insure that there will be adequate water flow before the unit can start. This will guard against slugging the compressors on start-up. It also serves to shut down the unit in the event that water flow is interrupted. A flow switch is available from McQuay under Part Number 017503300. It is a "paddle" type switch and adaptable to any pipe size from 1 inch to 8 inches. The flow switch should be adjusted to open at half the normal flow rate for the vessel. Follow the instructions that come with the flow switch.

Figure 2, Flow Switch Mounting

The flow switch connections to the unit control panel must be according to the Field Wiring Diagram, Figure 7, found on page 13. Install the switch according to manufacturer's instructions included with it.

CAUTION Freeze Notice: Neither the evaporator nor the condenser is self-draining;

both must be blown out. The piping should also include thermometers at the inlet and outlet connections and air vents at the high points.

The water heads can be interchanged (end for end) so that the water connections can be made at either end of the unit. If this is done, new head gaskets must be used and control sensors relocated. In cases where the water pump noise can be objectionable, isolation sections are recommended at both the inlet and outlet of the pump. In most cases, it will not be necessary to provide vibration eliminator sections in the condenser inlet and outlet water lines; but where noise and vibration are critical (for example, where a pipe chase goes through walls adjoining living quarters in an apartment building), they can be required.

Where a cooling tower is used to supply condenser water, a flow-balancing valve is required. Some form of temperature control is required if tower water becomes too cold.

Flow direction marked on switch

I in. (25mm) NPT flow switch connection

Tee


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 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 products 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, and loss of temperature control.

For normal comfort cooling applications where the cooling load changes relatively slowly, we recommend a minimum system volume of three minutes times the flow rate (gpm). For example, if the design chiller flow rate is 1000 gpm, we recommend a minimum system volume of 3000 gallons (1000 gpm x 3 minutes).

For process applications where the cooling load can change rapidly, additional system water volume is needed. A process example would be a quench tank where the load would be stable until the hot material is dipped into the water tank. Then, the load would increase drastically. Large storage capacity will usually be required for this type of application.

System volume = {1000 gpm x 3 minutes} + {(5 increment of 10% increase) x (3 minutes) x 1000 gpm} = 18,000 gallons

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 suggestions, the possibility of problems increases. We believe that these guidelines should be an industry standard and not just recommendations from McQuay.

Physical Data and Weights

Evaporator The insulation provided by McQuay of cold surfaces includes the evaporator and non-connection water head, suction piping, compressor inlet, motor housing, and motor coolant suction line. The insulation used is UL recognized. It is 3/4" thick vinyl nitrate polymer having a K factor of 0.28 at 75°F. The sheet insulation is fitted and cemented in place forming a vapor barrier, then painted with a resilient epoxy finish that resists cracking. The insulation complies to appropriate requirements or has been tested in accordance with the following:

HH-I-573 (GSA-FSS) ASTM-D-1149 ASTM-C-177 ASTM-C-534 ASTM-D-1056 UL 94-5V ASTM-C-355

Refrigerant side design pressure is 200 psi (1380 kPa). Water side design pressure is 150 psi (1034 kPa) with 300 psi (2068 kPa) available as an option.

Table 1, Evaporator Physical Data

WPV Model

Refrigerant Charge lb (kg)

Water Volume, gal (L)

Insulation Area

Sq Ft (m2)

Vessel Weight lb (kg)

Number of Relief Valves

Diameter in. (mm)

Length Ft. (mm)

240 482 (219) 39 (146) 66 (6.1) 3285 (1488) 1 22 (559) 9 (2743) 250 482 (219) 39 (146) 66 (6.1) 3285 (1488) 1 22 (559) 9 (2743) 280 853 (388) 73 (275) 102 (9.4) 4745 (2150) 1 26 (660) 12 (3660) 290 853 (388) 73 (275) 102 (9.4) 4745 (2150) 1 26 (660) 12 (3660) 320 853 (388) 73 (275) 102 (9.4) 4745 (2150) 1 26 (660) 12 (3660) 350 853 (388) 73 (275) 102 (9.4) 4745 (2150) 1 26 (660) 12 (3660) 390 853 (388) 73 (275) 102 (9.4) 4745 (2150) 1 26 (660) 12 (3660) 410 853 (388) 73 (275) 102 (9.4) 4745 (2150) 1 26 (660) 12 (3660) 430 1113 (505) 89 (336) 115 (10.6) 4776 (2166) 1 30 (762) 12 (3660)


Condenser Refrigerant side design pressure is 200 psi (1380 kPa). Water side design is 150 psi (1034 kPa) with 300 psi (2068 kPa) available as an option.

Table 2, Condenser Physical Data

WPV Model

Pumpdown Capacity lb (kg)

Water Volume gal (L)

Vessel Weight lb (kg)

Number of Relief Valves

Diameter in. (mm)

Length Ft. (mm)

240 728 (330) 42 (160) 1896 (860) 2 20 (508) 9 (2743)

250 728 (330) 42 (160) 1896 (860) 2 20 (508) 9 (2743)

280 1183 (537) 76 (290) 2838 (1287) 2 22 (559) 12 (3660)

290 1183 (537) 76 (290) 2838 (1287) 2 22 (559) 12 (3660)

320 1183 (537) 76 (290) 2838 (1287) 2 22 (559) 12 (3660)

350 1183 (537) 76 (290) 2838 (1287) 2 22 (559) 12 (3660)

390 1183 (537) 76 (290) 2838 (1287) 2 22 (559) 12 (3660)

410 1183 (537) 76 (290) 2838 (1287) 2 22 (559) 12 (3660)

430 1656 (751) 93 (353) 3650 (1660) 2 26 (660) 12 (3660)

Pumpdown To facilitate compressor service, all McQuay centrifugal chillers are designed to permit pumpdown and isolation of the entire refrigerant charge in the unit’s condenser. No separate pumpout receiver is required.

Oil Coolers McQuay WPV centrifugal chillers have a factory-mounted water-cooled oil cooler with a temperature controlled water-regulating valve and a solenoid valve.

Cooler cooling water connections are located below the compressor and are shown on the specific unit certified drawings.

Field water piping to the cooler inlet and outlet connections must be installed according to good piping practices and should include stop valves to isolate the cooler for servicing. A 3/4" minimum cleanable filter (40 mesh maximum), and drain valve or plug should also be field installed. The water supply for the oil cooler should be from the chilled water circuit or from an independent source such as city water. When using chilled water it is important that the water pressure drop across the evaporator is greater than the pressure drop across the oil cooler or insufficient oil cooler flow will result. If the pressure drop across the evaporator is less than the oil cooler, the oil cooler must be piped across the chilled water pump provided that its pressure differential is sufficient. The water flow through the oil cooler will be adjusted by the unit's regulating valve so that the temperature of oil supplied to the compressor bearings (leaving the oil cooler) is between 80°F and 110°F (27°C and 43°C).

Compressors using chilled water for oil cooling will often start with warm "chilled water" in the system until the chilled water loop temperature is pulled down. Data given here is for that condition. With cooling water in the 40°F to 55°F (4°C to 13°C) range considerably less water will be used and the pressure drop will be greatly reduced.

When supplied with city water, the oil piping should discharge through a trap into an open drain to prevent draining the cooler by siphoning. The city water can also be used for cooling tower makeup by discharging it into the tower sump from a point above the highest possible water level.

Oil Cooler Data Water Temp.

Unit Model Flow (gpm)

Press. Drop (ft) Inlet (°F) Outlet (°F)

All 12 32 80.0 87.0 Note: 1. Pressure drops include valve on the unit.


NOTE: Particular attention must be paid to chillers with variable chilled water flow through the evaporator. The pressure drop available at low flow rates can very well be insufficient to supply the oil cooler with enough water. In this case an auxiliary booster pump can be used or city water employed.

CONNECTION SIZES: WPV cooler connection sizes are 3/4 in. FPT.

Figure 3, Oil Cooler Piping Across Chilled Water Pump

CHILLER

OIL COOLER

STOPVALVE STRAINER

MAX. 40 MESH

SOLENOIDVALVE

DRAIN VALVEOR PLUG

STOPVALUE

PUMP

R

S

Figure 4, Oil Cooler Piping With City Water

COOLING TOWER

OPENDRAIN

DRAIN VALVEOR PLUG

SOLENOIDVALVE

OIL COOLER

WATERSUPPLY

STOPVALVE

STRAINERMAX. 40MESH

COOLING TOWER MAKEUPDISCHARGE ABOVEHIGHEST POSSIBLEWATER LEVEL

R

S

Figure 5, Oil Cooler Connections, WPV Units

Oil Reservoir

Solenoid Valve

Temperature Control Valve

Oil Pump Contactor

Inlet Connection

Outlet Connection

Compressor Microprocessor Controller

Oil Pump Capacitor

Relief Valve


Refrigerant Vent Piping As a precaution, each system is equipped with pressure relief valves located on the condenser, evaporator, and oil sump vessel for the purpose of relieving excessive refrigerant pressure to the atmosphere. Most codes require that relief valves be vented to the outside, and this is a desirable practice for all installations.

Note: Remove plastic shipping plugs (if installed) from the inside of the valves prior to making pipe connections. Whenever vent piping is installed, the lines should be run in accordance with local code requirements; where local codes do not apply, ANSI/ASHRAE Standard 15-1994 code recommendations should be followed.

The condenser design incorporates two relief valves (one set) with a three-way shutoff valve separating the two valves (see Figure 6, Condenser Relief Valve Set). One valve remains in the system at all times and the second valve acts as a standby. If one relief valve of the two-valve set fails, the shutoff valve can be used to isolate the faulty relief valve, while the other valve provides pressure protection.

Figure 6, Condenser Relief Valve Set

When piping the vent line to a dual valve set, it can be sized for one relief valve and piped to both valves. Connections are 1 inch FPT.

Vent piping is sized for only one valve of the set since only one can be in operation at a time. In no case would a combination of evaporator and condenser sizes require more refrigerant than the pumpdown capacity of the condenser. Condenser pumpdown capacities are based upon ANSI/ASHRAE Standard 15-1992 recommendations of 90% full at 90°F (32°C). To convert values to the older ARI standard, multiply pumpdown capacity by 0.888.

Relief Valve Pipe Sizing Relief valve pipe sizing is based on the discharge capacity for the given evaporator or condenser and the length of piping to be run. Discharge capacity for HFC-134a vessels is calculated as follows:

C xDxL= 0133.

Where: C=Minimum discharge capacity, lbs of air/min

D=Vessel diameter, in.

L=Vessel length, ft.


Example: WPV 240 evaporator, HFC-134a Refrigerant, 75 equivalent feet of piping

min/3.26922133.0 airofLbsxxC ==

From the table below, 75 feet of piping for 26.3 lb. of air/min. at 200 psig valve setting requires a 1.25" diameter pipe.

Table 3, Discharge Capacity, lbs of Air/Min EQUIVALENT DIAMETER STANDARD WALL IRON PIPE LENGTH OF 1” (25mm) 1.25” (32mm) 1.5” (38mm) 2” (50mm) 2.5” (64mm) 3” (76mm) DISCHARGE RELIEF VALVE PRESSURE SETTNG (psi)

PIPING, FT. (m) 200 200 200 200 200 200 50 (15.2) 24.1 48.2 66.6 131.6 204.9 354.5 75 (22.9) 19.7 39.4 57.9 107.3 169.3 289.6

100 (30.5) 17.1 29.0 49.9 92.9 145.8 250.3 150 (45.7) 14.0 27.8 40.5 75.7 118.5 204.9 200 (61.0) 12.1 24.1 35.3 65.7 102.5 177.4 300 (91.4) 10.0 19.7 28.7 53.6 85.0 144.6

Note: Standard relief valve settings: 1. Evaporator=200 psig, condenser=200 psig

NOTE: Per ASHRAE Standard 15, the pipe size can not be less than the relief device, meaning a minimum 1" diameter pipe is required. The discharge from more than one relief valve can be run into a common header, the area of which shall not be less than the sum of the areas of the connected pipes. For further details, refer to ASHRAE Standard 15. The common header can be calculated by the formula:

DCommon D D Dn= +��

��1

222 2 0 5

.....

NOTE: The above information is a guide only. Consult local codes and/or latest version of ASHRAE Standard 15 for sizing data.

Electrical Wiring, fuse and wire size must be in accordance with information located in the electrical data.

Important: The voltage to these units should be within the limitation of +10% of nameplate. The voltage unbalance between phases must not exceed 2% per NEMA MG-1, 1998 Standard. It is most important that the unbalance between phases be kept at a minimum.

Power Wiring

WARNING Qualified and licensed electricians must perform wiring. Shock hazard exists.

The McQuay start-up technician will determine proper phase sequence.

NOTE: Connections to terminals must be made with copper lugs and copper wire.

Under no circumstances should a compressor be brought up to speed unless proper sequence and rotation have been established. Serious damage can result if compressor starts in wrong direction.

Unit Mounted Starter Power Wiring All units are supplied with a factory-wired and mounted starter equipped with ambient compensated quick trip overloads. Wiring, fuse and wire size must be in accordance with information located in the electrical data supplied with the unit or the electrical data pertaining to your unit.


Important: See reference above to maximum voltage unbalance limitation of 3%.

The transition timer on wye-delta starters is factory set to disconnect the star winding connection and connect the delta winding, when the motor comes up to speed and before any speed reduction occurs.

Control Wiring The control circuit on the McQuay WPV packaged chiller is designed for 115 volts. Power can be supplied from a separate circuit and fused at 20 amps inductive load. However, since these units are supplied with a factory-mounted starter the control circuit power supply is provided through a transformer located in the starter.

The disconnect switch should be tagged to prevent current interruption. Switch is to remain on at all times in order to keep oil heaters operative and prevent refrigerant from diluting in oil.

The control panel off-on switch should be turned to the "off" position at any time compressor operation is not desired.

In the event control voltage is supplied by a separate transformer, the transformer should be rated at 2 KVA, with an inrush rating of 12 KVA minimum at 80% power factor and 95% secondary voltage. For control wire sizing, refer to N.E.C. Articles 215 and 310. In the absence of complete information to permit calculations, the voltage drop should be physically measured. Again, the disconnect switch should be marked to prevent control circuit from being de-energized. Water flow interlock terminals are provided on the control center terminal strip. See field connection diagram, Figure 7 on page 13, or in the cover of control center for proper connections.

The purpose of the water flow interlocks is to prevent compressor operation until such time as both the evaporator water and condenser water pumps are running.

Operation of the chilled water pump can be to cycle the pump with the compressor, operate continuously, or start automatically by a remote source. The cooling tower pump must cycle with the machine. The holding coil of the cooling tower pump motor starter must be rated at 115 volts, 60 Hz with a maximum volt-amperage rating of 100. If the voltage-amperage rating is exceeded, a control relay is required.

All interlock contacts must be rated for no less than 10 inductive amps. The alarm circuit provided in the control center utilizes 115 volts AC. The alarm used should not draw more than 10 volt amperes.

See OM CentrifMicro II for MicroTech II control details.

Testing Control Circuit McQuay will test the circuits upon completion of power and control wiring during unit's initial start-up.

Surge Capacitors All units (except those supplied with solid state starters) are supplied with surge capacitors to protect compressor motors from electrical damage resulting from high voltage spikes.

Wiring for Optional BAS Interface The optional Building Automation System (BAS) interface utilizing the MicroTech II unit controller’s Protocol Selectability™ feature is field wired and will be set-up by the McQuay startup service technician. The following manuals explain the wiring and mounting procedures:

LONWORKS > IM 735

BACnet > IM 736

MODBUS > IM 743


Figure 7, Field Wiring Diagram

80

* CHILLED WATER PUMP STARTERS

EWI-2

CP2

CP1

NOTE 8

NOTE 8

NOTE 8

*NOTE 5

NOTE 5

NOTE 6

H

O

A

C4

* COOLING TOWER

FIRST STAGE

STARTER

* COOLING TOWER

SECOND STAGE

STARTER

* COOLING TOWER

THIRD STAGE

STARTER

* COOLING TOWER

FOURTH STAGE

STARTER

* NOTE 7H

A

O

C3

* NOTE 7H

A

O

NOTE 7

NOTE 7

79

78

77

74

73

* REMOTE ON/OFF (NOTE 3)

54

CF

86

EF

86

EVAP.FLOW ORDELTA PSWITCH(NOTE 4)

COND.FLOW ORDELTA PSWITCH(NOTE 4)

C

CWI-2

CWI-1

(115V) (24V)

MICROTECH CONTROLBOX TERMINALS

5570

H

A

O

H

A

O

H

O

A C

H

O

A C

H

O

A C

NOTE 8

NOTE 6

EWI-1

C2

C1

*

*

*

*

*

*

UTB1

MODE SWITCH

CTB2

T3-S

76

75

PE

85

86

POWER

NEUTRALNOTE 7*

81

84

COMMON

POWER

A82(NO)

83(NC)

ALARMRELAY

(NOTE 2)NOTE 2*

* CONDENSER WATER PUMP STARTERS

EP2

EP1

GND

Notes: 1. Compressor motor starters are factory-mounted and wired. All line side power conductors must be copper. 2. A customer-furnished 24-volt alarm relay coil can be connected between terminals 81 and 82 of the control panel for normally-

open contacts and terminals 81 and 83 for normally-closed contacts. The alarm is operator programmable. Maximum rating of the alarm relay coil is 25-VA.

3. Remote On/Off control unit can be accomplished by installing a set of dry contacts between terminals 70 and 54. 4. Evaporator and condenser paddle-type flow switches or pressure differential switches are required and must be wired as

shown. Field-supplied pressure differential switches must be installed across the vessel and not the pump. 5. Optional customer-supplied 115-VAC 25-VA maximum coil rated chilled water pump relay (CHWR 1 and 2) can be wired as

shown. This option will cycle the chilled water pump in response to building load. 6. The condenser water pump must cycle with the unit. A customer supplied 115-VAC 25-VA maximum coil rated condenser

water pump relay (CWR 1 and 2) is to be wired as shown. 7. Optional customer supplied 115-VAC 25-VA maximum coil rated cooling tower fan relays can be wired as shown. This

option will cycle the cooling tower fans in order to maintain unit head pressure. 8. Auxiliary 24-VAC rated contacts in both the chilled water and condenser water pump starters must be wired as shown. 9. DC wiring must be run separately from 115 vac wiring. 10. All wiring to be NEC Class 1.


Prestart System Checklist Yes No N/A Chilled Water

Piping complete ................................................................................................................. � � �

Water system filled, vented................................................................................................ � � �

Pumps installed, (rotation checked), strainers cleaned ...................................................... � � �

Controls (3-way, face and bypass dampers, bypass valves, etc.) operable......................... � � �

Water system operated and flow balanced to meet unit design requirements .................... � � � Condenser Water

Cooling tower flushed, filled and vented .......................................................................... � � �

Pumps installed, (rotation checked), strainers cleaned ..................................................... � � �

Controls (3-way, bypass valves, etc.) operable ................................................................. � � �

Water system operated and flow balanced to meet unit requirements ............................... � � � Electrical

Optional 115 volt service completed, but not connected to control panel ........................ � � �

Power leads connected to starter ....................................................................................... � � � (Do not connect starter or compressor terminals) All interlock wiring complete between control panel and complies with specifications ... � � �

Pump starter and interlock wired ..................................................................................... � � �

Cooling tower fans and controls wired ............................................................................ � � �

Wiring complies with National Electrical Code and local codes ...................................... � � �

Condenser pump starting relay (CWR) installed and wired ............................................. � � � Miscellaneous

Oil cooler water piping complete .................................................................................... � � �

Relief valve piping complete ............................................................................................ � � �

Thermometer wells, thermometers, gauges, control wells, controls, etc., installed .......... � � �

Minimum system load of 80% of machine capacity available for testing and adjusting controls........................................................................................................ � � �

Note: This checklist must be completed and sent to the local McQuayService location two weeks prior to start-up.


Operation

Operator Responsibilities It is important that the operator become familiar with the equipment and the system before attempting to operate the chiller. In addition to reading this manual, the operator should study operation manual OM CentrifMicro II (latest edition) and the control diagram furnished with the unit so that he understands the starting, operating and shutdown sequences as well as the equipment protection shutdown modes.

During the initial startup of the chiller the McQuay technician will be available to answer any questions and instruct in the proper operating procedures.

It is recommended that the operator maintain an operating log for each individual chiller unit. In addition, a separate maintenance log should be kept of the periodic maintenance and servicing activities.

This McQuay centrifugal chiller represents a substantial investment and deserves the attention and care normally given to keep this equipment in good working order. If the operator should encounter abnormal or unusual operating conditions, it is recommended that a McQuay service technician be consulted.

McQuay International conducts training for centrifugal operators at its factory Training Center several times a year. These sessions are structured to provide basic classroom instruction and include hands-on operating and troubleshooting exercises. For further information, contact your McQuay representative.

Standby Power It is essential that any centrifugal chiller connected to standby power come to a complete stop and then be restarted with the standby power. Attempting to switch from regular line power to auxiliary power while the compressor is running can result in extreme transient torque that will severely damage the compressor.

Nomenclature Each centrifugal chiller is assigned a set of identifying numbers that are used to describe the unit features and to identify each individual unit. These number groups are stamped on each unit nameplate.

All inquiries pertaining to operating and servicing of this unit should include the unit serial number that is on the nameplate located on the unit control panel.

Each of the major individual components also has a nameplate to provide certain necessary information to the installer and the operator.

Compressors are designated as model CE XXX. The compressor nameplate identifies the compressor model, style and serial number and includes the electrical characteristics of the compressor motor.

The condenser and evaporator vessels have nameplates stamped with the maximum working pressure of the vessel, the National Board Number, and the vessel style number. It should be noted that the vessel relief valve maximum settings coincides with the maximum refrigerant side vessel working pressure.

Operating Limits The maximum temperature of water entering the chiller on standby must not exceed 110°F (43.3°C). Maximum temperature entering on start-up must not exceed 90°F (32.2°C). Minimum chilled water leaving temperature without antifreeze is approximately 38°F (3.3°C), but can vary up or down two degrees depending on actual component selection.


MicroTech II Control The MicroTech II control system is distributed between a unit microprocessor based control, a compressor microprocessor based control and a 10 inch color VGR touch-screen interface panel. The system is designed to initiate the step-by-step starting functions of the centrifugal compressor, monitor and regulate the compressors capacity, protect it, and sequence the compressor shutdown on lack of load or in response to an external disable signal.

The full information on the features, operation and problem analysis of the McQuay microprocessor control for WPV units, see Operators Manual OM CentrifMicro II (latest version). The MicroTech II panel provides a wide range of control options and data reporting and recording capability. Familiarity with the control system is essential for optimum unit operation.

Capacity Control System The movement of the inlet vanes, opening or closing to permit the correct quantity of refrigerant to enter the impeller, controls the compressor capacity. The vane movement occurs in response to oil flow from 4-way solenoid valve which in turn, responds to a control signal from the compressor controller. This oil flow activates a piston to rotate the vanes.

Vane Operation The hydraulic system for the inlet guide vane capacity control operation consists of a 4-way normally open solenoid valve located on the compressor close to the suction connection. Oil under pressure from the oil filter enters the solenoid valve and is then directed by the 4-way valve to either or both sides of the piston depending on whether the control signal is to load, unload, or hold.

To open the vanes (or load the compressor) solenoid SA is de-energized and solenoid SB is energized, allowing oil flow from port SA to one side of the piston then drain through port SB.

To close the vanes (unload compressor) valve SB is de-energized and valve SA is energized to move the piston and vanes toward the unload position.

When both solenoid valves SA and SB are de-energized, full oil pressure is directed to both sides of the piston through ports SA and SB, thus the vanes are held in that position. Refer to Figure 9 and Figure 10 for solenoid action. Note that both solenoids cannot be energized simultaneously.

Metering Valves The speed at which the capacity control vanes are opened or closed can be adjusted to suit system operating requirements. Adjustable needle valves in the oil drain lines are used to control the rate of bleed-off and consequently the “vane speed”. These needle valves are part of the 4-way solenoid valve assembly located on the compressor at the suction end.

The valves are normally factory set so the vanes will move from fully closed to fully opened in approximately 3 to 5 minutes and from fully open to fully closed in 1 to 2 minutes. The speed should be slow enough to prevent over-controlling and hunting.

Vane Speed Adjustment The vane speed at which the capacity control vanes open or close is controlled by the rate of oil bleed-off from the vane actuating position. This bleed-off rate is adjustable by positioning the needle valves on SA and SB solenoid valves located on the compressor.

The upper needle valve (SB) is for adjusting the vane OPENING speed for loading the compressor. Turn this screw clockwise to decrease the vane opening and counterclockwise to increase the opening speed.

The lower needle valve (SA) is for adjusting the CLOSING speed for unloading the compressor. The same adjustment applies . . . clockwise to decrease closing, counterclockwise to increase vane closing.


Figure 8, Lube Box, WPV Units

Figure 9, Vane Control Solenoid Operation

CompressorUnloaderCylinder

Floating Piston Linked to Inlet VanesOpens VanesCloses Vanes

Four-Way SolenoidValve Located on

Compressor or in Lube Box

Piston Drain

#3 Outlet

SB

SA

#1 Inlet

LEGEND

Oil Under Pressure

To OilPump Sump

Section “SB”De-energized

Section “SA”De-energized

From OilPump Discharge

Adjustable Needle ValvesIntegral With Four-Way

Solenoid Valve

HOLDING

Contactor

Pump Motor Overload

Run Capacitor

NOTE 4-Way Solenoid and

Vane Close Switch Are Located on the

Compressor


Figure 10, Vane Control Solenoid Operation, Continued

Drain From Piston #3 Outlet

SB

SA

#1 Intlet

LEGEND

Oil Under Pressure

To OilPump Sump

Section “SB”Energized

Section “SA”De-energized


OPENINGOil Sump Pressure

Drain From Piston

#3 Outlet

SB

SA

#1 Intlet

To OilPump Sump

Section “SB”De-energized

Section “SA”Energized


CLOSING

Piston Drain

Lubrication System The lubrication system for the WPV centrifugal units provides lubrication and heat removal for compressor bearings and internal parts. In addition, the system provides oil under pressure to hydraulically operate the unloading piston for positioning the inlet guide vanes for capacity control.

Proper operation of the hydraulic system and bearing lubrication system requires that the recommended oil be used as shown in Table 4, Approved Polyolester Oils For R-134a Units.

Each unit is factory charged with the correct amount of the recommended oil. Under normal operation, no additional should be needed. Oil should be visible in the oil sump sight glass at all times.

The units have a separate oil pump contained in the oil reservoir. The reservoir includes pump, motor, heater and oil/vapor separator system. Oil is pumped through the water-cooled external oil cooler and then to the oil filter located inside the compressor housing.

The oil coolers maintain the proper oil temperature under normal operating conditions. The factory-mounted coolant flow control valve should maintain 90°F-100°F (32°C-38°C). A spring-loaded piston in the compressor provides lubrication protection for coast-down in the event of a power failure. When the oil pump is started, the piston is forced back by the oil pressure, compressing the spring and filling the piston cavity with oil. When the pump stops, the spring pressure on the piston forces the oil out to the bearings.

A typical flow diagram is shown in Figure 11


Table 4, Approved Polyolester Oils For R-134a Units

Compressor Models All

Lubricant Designation Mobil Artic EAL 46;

ICI Emkarate RL32H(2)

Container Size

55 Gal. Drum

5 Gal. Drum

1 Gal. Can

McQuay Part Number

735030432, Rev 47

735030433, Rev 47

735030435, Rev 47

Compressor Oil Label 070200106, Rev OB NOTE: Approved oil from two suppliers can be mixed.

Figure 11, Typical Oil Flow Diagram

NOTES: 1. Connections not necessarily in correct relative location. 2. R=Relief Valve, S=Solenoid Valve, P=Pressure Sensor, T=Temperature Sensor


Pressure Drops

Figure 12, Evaporator Pressure Drops

98

7

6

5

4

3

2724

21

18

15

12

9

100 200 300 400 500 600 700 800 9001000 2000

Flow Rate (GPM)

Pres

sure

Dro

p (ft

of w

ater

)Flow Rate (L/s)

6 13 19 25 32 38 44 50 57 63 126

60

90

120

150

180

210

240

270

300

PressureD

rop(kPa)

10

20

30

40

50

60

70

80

90

100

WPV 240, 250

WPV 430

WPV 280, 290, 320,350, 390, 410

Minimum and Maximum Flow Rates Minimum Flow Maximum Flow WPV Model

GPM (LPS) FT (kPa) GPM (LPS) FT (kPa) 240 330 (20.8) 7.6 (22.8) 960 (60.6) 51 (153) 250 375 (23.7) 10.0 (30.0) 1000 (63.1) 55 (165) 280 390 (24.6) 5.0 (15.0) 1112 (70.2) 41 (123) 290 435 (27.4) 6.0 (18.0) 1160 (73.2) 42 (126) 320 450 (28.4) 6.5 (19.5) 1280 (80.8) 47 (141) 350 495 (31.2) 8.1 24.3) 1400 (88.3) 55 (165) 390 540 (34.1) 10.0 (30.0) 1560 (98.4) 68 (204) 410 600 (37.9) 12.0 (36.0) 1640 (103.5) 70 (210) 430 630 (39.8) 10.1 (30.3) 1700 (107.3) 61 (183)


Figure 13, Condenser Pressure Drops

98

7

6

5

4

3

2724

21

18

15

12

9

100 200 300 400 500 600 700 800 9001000 2000

Flow Rate (GPM)

Pres

sure

Dro

p (ft

of w

ater

)

Flow Rate (L/s)

6 13 19 25 32 38 44 50 57 63 126

60

90

120

150

180

210

240

270

300

PressureD

rop(kPa)

10

20

30

40

50

60

70

80

90

100

WPV 240, 250 WPV 430

WPV 280, 290, 320,350, 390, 410

Minimum Flow Maximum Flow WPV Model GPM (LPS) FT (kPa) GPM (LPS) FT (kPa)

240 440 (27.8) 4.1 (12.3) 960 (60.6) 20.0 (60.0) 250 500 (31.6) 5.6 (16.8) 1000 (63.1) 21.0 (63.0) 280 500 (31.6) 5.2 (15.6) 1112 (70.2) 23.0 (69.0) 290 580 (36.6) 7.0 (21.0) 1160 (73.2) 24.5 (73.5) 320 600 (37.9) 7.5 (22.5) 1200 (75.7) 25.0 (75.0) 350 660 (41.6) 9.2 (27.6) 1400 (88.3) 34.0 (102.0) 390 720 (45.4) 11.0 (33.0) 1560 (98.4) 41.0 (123.0) 410 800 (50.5) 13.0 (39.0) 1640 (103.5) 45.0 (135.0) 430 840 (53.0) 12.0 (36.0) 1700 (107.3) 38.5 (115.5)


Dimensions

WPV Chillers Figure 14 WPV 240A, 250A

EVAPORATOR

CONDENSER

37.85(961) 110.55

(2808)

3.57(91)

5.63(143)

134.3(3411)

11.63(295)

50.42(1281)

27.2(691)

23(584)

51.87(1317)

71.85(1825)

IN OUT

IN

OUT

4.52(115)

STARTER

17.8(452)

4(102)

8.56(217)

25.56(649)

42.12(1070)

34.12(867)

59.92(1522)

14.75(375)

5.63(143)

5.63(143)

1

22

5

08

065.59(142)

5.59(142)36.87

(936)

A ir C o n di ti on i ng

A LARMVIEW

SET

<<<

STARTER

1” FPT OIL COOLERCONNECTION

TOP CABLE ENTRY

CONTROLCONNECTIONS

31.19(792)

X

Y

Z

Water Volume gal (l) Center of Gravity In. (mm) Weight

Lbs (kg) Evaporator Condenser X Y Z Refrigerant

Lbs (kg) Operating 10900 (4945) 39 (146) 42 (160) 50 (1270) 37 (940) 13 (330) 482 (219) Shipping 10227 (4639) 39 (146) 42 (160) 49 (1245) 37 (940) 13 (330)

Notes: 1. 1 in. (25mm) FPT evaporator and condenser relief valves must be piped per ANSI/ASHRAE 15. 2. At a minimum, length of tube sheet to tube sheet dimensions is required at either end for tube removal, 26 in. (914mm) is required at

other end and each side and top for service. 3. Final connections must allow for 0.5 in. (12.7mm) manufacturing tolerance. 4. 2.5 in. (64mm) diameter lifting holes are provided. 5. All water connections are given in standard U.S. pipe size. Standard connections are suitable for welding or victualic couplings. 6. Vibration isolator pads are provided for field installation [0.25 in (6mm) thick when loaded]. 7. If main power wiring is brought up through the floor, this wiring must be outside the envelope of the unit. 8. The shipping skid adds 4 in (105mm) to the overall unit height. 9. Right hand connections are shown. Left hand connections are available as an option.


Figure 15, WPV 280A to 290A

EVAPORATOR

CONDENSER

23(584)

55.87(1419)

2

37.85(961)

145.44(3694)

6.125(156)

21.02(534)

170.07(4320)

17.63(448)

2

54.43(1383)

28.2(716)

71.85(1825)

38.87(987)

14.62(371)

4(102)

11.06(281)

29.27(743)

45.83(1164)

37.83(961)

60.45(1535)

14.75(375)

5

08

08

OUT

7.07(180)

IN

7.07(180)

OUT

IN

5.59(142)

5.59(142)

8.52(216)

1

STARTER

A ir Co n d it io n in g

ALARMVIEWSET

<<<STARTER


TOP CABLE ENTRY

CONTROLCONNECTIONS

31.19(792)

X

Z

11.63(295.4)

Y

Water Volume gal (l) Center of Gravity In. (mm) Weight Lbs (kg) Evaporator Condenser X Y Z

Refrigerant Lbs (kg)

Operating 14129 (6408) 73 (275) 77 (290) 67 (1702) 36 (914) 17 (432) 853 (388) Shipping 12882 (5843) 73 (275) 77 (290) 66 (1676) 36 (914) 17 (432)

Note: See notes on page 22.


Figure 16, WPV 320A to 410A

EVAPORATOR

CONDENSER

23(584)

53.56(1360)

2

37.85(961)

145.44(3694)

6.125(156)

21.02(534)

170.07(4320)

17.63(448)

2

52.11(1324)

28.2(716)

71.85(1825)

36.56(929)

14.62(371)

4(102)

11.06(281)

32.46(824)

49.02(1245)

41.02(1042)

63.64(1616)

14.75(375)

5

08

08

OUT

7.07(180)

IN

7.07(180)

OUT

IN

5.59(142)

5.59(142)

6.21(158)

1

STARTER

A i r C on d it i on i ng

ALARMVIEW

SET

<<<STARTER


TOP CABLE ENTRY

CONTROLCONNECTIONS

28.85(732.8)

X

Y

Z

11.63(295.4)

Water volume gal (l) Center of Gravity In. (mm) Weight

Lbs (kg) Evaporator Condenser X Y Z Refrigerant

Lbs (kg) Operating 14731 (6682) 73 (275) 77 (291) 67 (1702) 36 (915) 18 (457) 853 (388) Shipping 13484 (6116) 73 (275) 77 (291) 66 (1676) 36 (915) 18 (457)

Note: See notes on page 22.


Figure 17, WPV 430A

EVAPORATOR

CONDENSER

23(584)

63.63(1616)

2

37.85(961)

145.44(3694)

7.005(178)

21.02(534)

167.07(4244)

11.625(295)

2

60.94(1548)

32.64(829)

71.85(1825)

43.44(1103)

14.62(371)

4(102)

13.06(332)

37.2(945)

56.26(1429)

48.26(1226)

70.94(1802)

17.25(438)

5

10

08

OUT

8.13(207)

IN

8.13(207)

OUT

IN

7.07(180)

7.07(180)

16.21(412)

1

STARTER

A i r C o nd i ti o n in g

ALARMVIEW

SET

<<<STARTER


TOP CABLE ENTRY

CONTROLCONNECTIONS

38.92(988.6)

X

Y

Z

Water Volume gal (l) Center of Gravity In. (mm) Weight Lbs (kg) Evaporator Condenser X Y Z

Refrigerant Lbs (kg)

Operating 17056 (7737) 89 (337) 93 (353) 68 (1727) 41 (1041) 21 (534) 1114 (505) Shipping 15534 (7046) 89 (337) 93 (353) 67 (1702) 41 (1041) 22 (559) Note: See notes on page 22.


Maintenance

R-134a Pressure/Temperature Chart HFC-134a Temperature Pressure Chart

°F PSIG °F PSIG °F PSIG °F PSIG

6 9.7 46 41.1 86 97.0 126 187.3

8 10.8 48 43.2 88 100.6 128 192.9

10 12.0 50 45.4 90 104.3 130 198.7

12 13.2 52 47.7 92 108.1 132 204.5

14 14.4 54 50.0 94 112.0 134 210.5

16 15.7 56 52.4 96 115.9 136 216.6

18 17.1 58 54.9 98 120.0 138 222.8

20 18.4 60 57.4 100 124.1 140 229.2

22 19.9 62 60.0 102 128.4 142 235.6

24 21.3 64 62.7 104 132.7 144 242.2

26 22.9 66 65.4 106 137.2 146 249.0

28 24.5 68 68.2 108 141.7 148 255.8

30 26.1 70 71.1 110 146.3 150 262.8

32 27.8 72 74.0 112 151.1 152 270.0

34 29.5 74 77.1 114 155.9 154 277.3

36 31.3 76 80.2 116 160.9 156 284.7

38 33.1 78 83.4 118 166.0 158 292.2

40 35.0 80 86.7 120 171.1 160 299.9

42 37.0 82 90.0 122 176.4 162 307.8

44 39.0 84 93.5 124 181.8 164 315.8

Routine Maintenance Lubrication (See Caution) After the system is once placed into operation, no other additional oil is required except in the event that repair work becomes necessary to the oil pump or unless a large amount of oil is lost from the system due to a leak.

If oil must be added with the system under pressure, use a hand pump with its discharge line connected to the service valve at the bottom of the oil sump. Oil can also be drained from this connection. The POE oils used with R-134a are hygoscopic and care should be exercised to avoid exposure to moisture (air).

Changing Oil Filters (See Caution) McQuay chillers are at positive pressure at all times and do not leak contaminated moist air into the refrigerant circuit eliminating the need for annual oil changes. An annual laboratory oil check is recommended to check overall compressor condition.


The oil filter in the compressors can be changed by simply isolating the filter cavity. Close the oil discharge line service valve at the oil pump. Remove the filter cover; some foaming can occur but the check valve should limit leakage from other compressor cavities. Remove the filter, replace with new element and replace filter cover using new gasket. Reopen the valve in pump discharge line and purge air from the oil filter cavity.

When machine is operated again, the oil level should be checked to determine if oil needs to be added to maintain the proper operating level.

CAUTION Improper servicing of the lubrication system,

including the addition of excessive or incorrect oil, substitute quality oil filter, or mishandling of the equipment under pressure is hazardous.

Only authorized and trained service personnel should attempt this service. For qualified assistance, contact your local McQuay service location.

Refrigerant Cycle Maintenance of the refrigerant cycle consists of maintaining a log of the operating conditions, and assuring the unit has the proper oil and refrigerant charge. (See the maintenance schedule at the end of this manual).

At every inspection, the oil, suction and discharge pressures should be noted and recorded, as well as condenser and chiller water temperatures.

The suction line temperature at the compressor should be taken at least once a month. Subtracting from this, the saturated temperature equivalent of the suction pressure will give the superheat. Extreme changes in subcooling and/or superheat over a period of time will indicate losses of refrigerant or possible deterioration of the expansion valves. Proper superheat setting is 0 to 1 degree F (0.5 degree C) at full load. Such a small temperature difference can be hard to measure accurately. Another method is to measure the compressor discharge superheat, the difference between the actual discharge temperature and the saturated discharge temperature. The discharge superheat should be between 14 and 16 degrees F (8 to 9 degrees C) at full load with R-134a refrigerant. The liquid injection should be deactivated when taking the discharge temperature. This is accomplished by removing the screw securing the connector to the solenoid valve (in the liquid injection feed line) and pulling the connector from the valve. The superheat will increase linearly to 55 degrees F (30 degrees C) at 10% load. The MicroTech II control can display all superheat and subcooling temperatures.


Figure 18, Typical Refrigerant Flow Diagram

1. Evaporator connections not necessarily in correct relative location. 2. R=Relief Valve, T=Temperature Sensor, P=Pressure Sensor

Electrical System Maintenance of the electrical system involves the general requirement of keeping contacts clean and connections tight and checking on specific items as follows:

1. The compressor current draw should be checked and compared to nameplate RLA value. Normally the actual current will be lower since the nameplate rating represents full load operation. Also check all pump and fan motor amperages and compare with nameplate ratings.

2. Inspection should verify that the oil heaters are operative. The heaters are insert cartridge type and can be checked by ammeter reading. They should be energized whenever power is available to the control circuit and when the compressor is inoperative. When the compressor starts the heaters are de-energized.

3. At least once a quarter, all controls except compressor overloads should be made to operate and their operating points checked. Any control can shift its operating point as it ages, and this must be detected so the controls can be adjusted or replaced. Pump interlocks and flow switches should be checked to be sure they interrupt the control circuit when tripped.

4. The contactors in the motor starter should be inspected and cleaned quarterly. Tighten all terminal connections.

5. The compressor motor resistance to ground should be checked and logged semi-annually. This log will track insulation deterioration. A reading of 50 megohms or less indicates a possible insulation defect or moisture and should be further checked.

CAUTION Never Megger a motor while in a vacuum. Severe damage can result.


6. The centrifugal compressor must rotate in the direction indicated by the arrow on the casting near the rotation sightglass. If the operator has any reason to suspect that the power system connections may have been altered, (phases reversed) the compressor should be jogged to check rotation. For assistance, call the McQuay service location.

Cleaning and Preserving A common cause of service calls and equipment malfunction is dirt. This can be prevented with normal maintenance. Remove and clean strainers in chilled water system, oil cooler line and condenser water system at every inspection.

Seasonal Servicing Prior to shutdown periods and before starting up again, the following service procedures should be completed.

Annual Shutdown Where the chiller may be subject to freezing temperatures, the condenser and chiller water piping should be disconnected and drained of all water. Dry air blown through the evaporator and condenser will aid in forcing all water out. Removal of condenser heads is also recommended. The condenser and evaporator are not self-draining. Water permitted to remain in the piping and vessels will rupture these parts if subjected to freezing temperature.

Forced circulation of antifreeze through the water circuits is a sure method of avoiding freeze up.

1. Take measures to prevent the shutoff valve in the water supply line from being accidentally turned on.

2. If a cooling tower is used and if the water pump will be exposed to freezing temperatures, be sure to remove the pump drain plug and leave it out so any water that may accumulate will drain away.

3. Open the compressor disconnect switch, and remove the Fusetrons. If the transformer is used for control voltage, the disconnect must remain on to provide power to the oil heater. Set the manual stop/auto switch (SWI) to the stop position. To insure against the possibility of an accidental start, remove the fault relay from the left side of the MicroTech panel.

4. Check for corrosion and clean and paint rusted surfaces.

5. Clean and flush water tower for all units operating on a water tower. Make sure tower “blowdown” or bleed-off is operating. Set up and use a good maintenance program to prevent “liming up” of both tower and condenser. It should be recognized that atmospheric air contains many contaminants that increase the need for proper water treatment. The use of untreated water can result in corrosion, erosion, sliming, scaling or algae formation. It is recommended that the service of a reliable water treatment company be used. McQuay International assumes no responsibility for the results of untreated or improperly treated water.

6. Remove condenser heads at least once a year to inspect the condenser tubes and clean if required.

Annual Startup A dangerous condition can exist if power is applied to a faulty compressor motor starter that has been burned out. This condition can exist without the knowledge of the person starting the equipment.

This is a good time to check all the motor winding resistance to ground. Semi-annual checking and recording of this resistance will provide a record of any deterioration of the winding insulation. All new units have well over 100 megohms resistance between any motor terminal and ground.

Whenever great discrepancies in readings occur or uniform readings of less than 50 megohms are obtained, the motor cover should be removed for inspection of the winding prior to starting the unit. Uniform readings of less than 5 megohms indicate motor failure is imminent and motor should be replaced or repaired. Repair before failure occurs can save a great deal of time and labor expended in the cleanup of a system after motor burnout.


1. The control circuit should be energized at all times. If the control circuit has been off and oil is cool, energize oil heaters and allow 24 hours for heater to remove refrigerant from the oil before starting.

2. Check and tighten all electrical connections.

3. Replace the drain plug in cooling tower pump if it was removed at shutdown time the previous season.

4. Install Fusetrons in main disconnect switch (if removed).

5. Reconnect water lines and turn on supply water. Flush out condenser and check for leaks.

6. Refer to Manual OM CentrifMicro II before energizing the compressor circuit.

Repair of System Pressure Relief Valve Replacement Current condenser designs use two relief valves (1 set) separated by a three way shutoff valve. This valve allows either relief valve to be shut off, but at no time can both be shut off. In the event one of the relief valves are leaking in the two valve set, these procedures should be followed:

• If the valve closest to the valve stem is leaking, back seat the three-way valve all the way, closing the port to the leaking pressure relief valve. Remove and replace the faulty relief valve. The three-way shutoff valve should remain either fully back seated or fully forward to normal operation. If the relief valve farthest from the valve stem is leaking, front seat the three-way valve and replace the relief valve as stated above.

• The refrigerant in the evaporator must be pumped down to the condenser to replace its single relief valve.

Pumping Down If it becomes necessary to pump the system down, extreme care should be used to avoid damage to the evaporator from freezing. Always make sure that full water flow is maintained through the chiller and condenser while pumping down. To pump the system down, close all liquid line valves. With all liquid line valves closed and water flowing, start the compressor. Set the MicroTech II panel to the manual load. The vanes must be open while pumping down to avoid a surge or other damaging condition. Pump the unit down until the MicroTech II cuts out at approximately 20 psig. It is possible that the unit might experience a mild surge condition prior to cutout. If this should occur immediately shut off the compressor. Use a portable condensing unit to complete the pump down, condense the refrigerant, and pump it into the condenser or pumpout vessel using approved procedures.

A pressure-regulating valve should always be used on the drum being used to build the system pressure. Also, do not exceed the test pressure given above. When the test pressure is reached disconnect the gas cylinder.

Pressure Testing No pressure testing is necessary unless some damage was incurred during shipment. Damage may be determined upon a visual inspection of the exterior piping assuring no breakage occurred or fittings loosened. Service gauges should show a positive pressure. If no pressure is evident on the gauges, a leak may have occurred discharging the entire refrigerant charge. In this case, the unit should be leak tested to determine the location of the leak.

Leak Testing In the case of loss of the entire refrigerant charge, the unit should be checked for leaks prior to charging the complete system. This can be done by charging enough refrigerant into the system to build the pressure up to approximately 10 psig (69 kPa) and adding sufficient dry nitrogen to bring the pressure up to a maximum of 125 psig (860 kPa) and then leak test with an electronic leak detector. Halide leak detectors do not function with R-134a. Water flow through the vessels should be maintained anytime refrigerant is added or removed from the system.


CAUTION Do not use oxygen or a mixture of R-22 and air to build up pressure as a serious explosion can result. If any leaks are found in welded or brazed joints or it is necessary to replace a gasket, relieve the test pressure in the system before proceeding. For copper joints, brazing is required.

After making any necessary repair, the system should be evacuated as described in the section following.

Evacuation After it has been determined that there are no refrigerant leaks the system should be evacuated using a vacuum pump with a capacity that will reduce the vacuum to at least 1000 microns of mercury. A mercury manometer, electronic or other type of micron gauge should be connected at the farthest point from the vacuum pump. For readings below 1000 microns, an electronic or other micron gauge should be used. The triple evacuation method is recommended and is particularly helpful if the vacuum pump is unable to obtain the desired 1 millimeter of vacuum. The system is first evacuated to approximately 29 inches of mercury. Dry nitrogen is then added to the system to bring the pressure up to zero pounds. Then the system is once again evacuated to approximately 29 inches of mercury. This is repeated three times. The first pulldown will remove about 90% of the noncondensables, the second about 90% of that remaining from the first pulldown and, after the third, only 1/10-1% noncondensables will remain.

Charging the System WPV water chillers are leak tested at the factory and shipped with the correct charge of refrigerant as indicated on the unit nameplate. In the event the refrigerant charge was lost due to shipping damage, the system should be charged as follows after first repairing the leaks and evacuating the system.

a. Connect the refrigerant drum to the gauge port on the liquid line shutoff valve and purge the charging line between the refrigerant cylinder and the valve. Then open the valve to the mid-position.

b. Turn on both the cooling tower water pump and chilled water pump and allow water to circulate through the condenser and the chiller. (It will be necessary to manually close the condenser pump starter.)

c. If the system is under a vacuum, stand the refrigerant drum with the connection up and open the drum and break the vacuum with refrigerant gas to a saturated pressure above freezing.

d. With a system gas pressure higher than the equivalent of a freezing temperature, invert the charging cylinder and elevate the drum above the condenser. With the drum in this position, valves open, water pumps operating, liquid refrigerant will flow into the condenser. Approximately 75% of the total requirement estimated for the unit can be charged in this manner.

e. After 75% of the required charge has entered the condenser, reconnect the refrigerant drum and charging line to the service valve on the bottom of the evaporator. Again purge the connecting line, stand the drum with the connection up, and place the service valve in the open position.

IMPORTANT: At this point the charging position should be interrupted and prestart checks made before attempting to complete refrigerant charge. The compressor must not be started at this time. (Preliminary check must first be completed.)

NOTE: It is of utmost importance that all local, national, and international regulations concerning the handling and emission of refrigerants are observed.


Maintenance Schedule

Maintenance Check List Item

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I. Unit

· Operational Log O

· Analyze Operational Log O · Refrigerant Leak Test Chiller O · Test Relief Valves or Replace X

II. Compressor · Vibration Test Compressor X A. Motor · Meg. Windings (Note 1) X · Ampere Balance (within 10% at RLA) O · Terminal Check (Infrared temperature measurement) X · Motor Cooling Filter Drier Pressure Drop X B. Lubrication System · Clean Oil Cooler Strainer (water) X · Oil Cooler Solenoid Operation O · Oil Appearance (clear color, quantity) O - Oil Filter Pressure Drop O · Oil Filter Change X X · Oil Analysis X · Oil change if indicated by oil analysis X C. Replace O Rings / Internal Inspection X

III. Controls A. Operating Controls · Calibrate Temperature Transducers X · Calibrate Pressure Transducers X · Check Vane Control Setting and Operation X · Verify Motor Load Limit Control X · Verify Load Balance Operation X · Check Oil Pump Contactor X B. Protective Controls · Test Operation of: Alarm Relay X Pump Interlocks X Guardistor and Surgeguard Operation X High and Low Pressure Cutouts X Oil Pump Pressure Differential Cutout X Oil Pump Time Delay X Continued on next page.


Maintenance Schedule, Cont.

Maintenance Check List Item

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IV. Condenser A. Evaluation of Temp Approach (NOTE 2) O B. Test Water Quality V C. Clean Condenser Tubes (NOTE 2) X X D. Eddy current Test - Tube Wall Thickness V E. Seasonal Protection X

V. Evaporator

A. Evaluation of Temp Approach (NOTE 2) O B. Test Water Quality V C. Clean Evaporator Tubes (NOTE 3) X D. Eddy current Test - Tube Wall thickness V X E. Seasonal Protection X

VI. Expansion Valves

A.Operational Evaluation (Superheat Control) X

VII. Starter(s)

A. Examine Contactors (hardware and operation) X B. Verify Overload Setting and Trip X C. Test Electrical Connections (Infrared temp measurement) X

VIII. Optional Controls

A. Hot Gas Bypass (verify operation) X

KEY: O = Performed by in-house personnel. X = Performed by McQuay authorized service personnel. (NOTE 4) V = Normally performed by third parties.

NOTES: 1. Some compressors use power factory correction capacitors and all have a surge capacitor (excepting units with

solid state starters). The surge capacitor can be installed out of sight in the compressor motor terminal box. In all cases, capacitors must be disconnected from the circuit to obtain a useful Megger reading. Failure to do so will produce a low reading. In handling electrical components, only fully qualified technicians must attempt service.

2. Approach temperature (the difference between the leaving water temperature and the saturated refrigerant temperature) of either the condenser or evaporator is a good indication of tube fouling, particularly in the condenser, where constant flow usually prevails. McQuay's high efficiency heat exchangers have very low design approach temperatures, in the order of one to one and one half degrees F. The chiller unit controller can display the water and the saturated refrigerant temperatures. Simple subtraction will give the approach. It is recommended that benchmark readings (including condenser pressure drop to confirm future flow rates) be taken during startup and then periodically afterward. An approach increase of two-degrees or more would indicate that excessive tube fouling could be present. Higher than normal discharge pressure and motor current are also good indicators

3. Evaporators in closed fluid circuits with treated water or anti-freeze are not normally subject to fouling, hover it is prudent to check the approach periodically.

4. Performed when contracted for, not part of standard initial warranty service.


Service Programs

It is important that an air conditioning system receive adequate maintenance if the full equipment life and full system benefits are to be realized.

Maintenance should be an ongoing program from the time the system is initially started. A full inspection should be made after 3 to 4 weeks of normal operation on a new installation and on a regular basis thereafter.

McQuay offers a variety of maintenance services through the local McQuay service office, its worldwide service organization, and can tailor these services to suit the needs of the building owner. Most popular among these services is the McQuay Comprehensive Maintenance Contract.

For further information concerning the many services available, contact your local McQuay service office.

Operator Schools

Training courses for Centrifugal Maintenance and Operation are held through the year at the McQuay Training Center in Verona, Virginia. The school duration is three and one-half days and includes instruction on basic refrigeration, MicroTech controls, enhancing chiller efficiency and reliability, MicroTech troubleshooting, system components, and other related subjects. Further information can be found on www.mcquay.com or call the McQuay Training Department at 540-248-0711.

Post Office Box 2510, Staunton, Virginia 24402-2510 • (800) 432-1342 • www.mcquay.com IOMM WPV (10/05)

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