Installation Maintenance Manual
IMM WMC-1
Dual Compressor Centrifugal Chillers
with Magnetic Bearings
Model WMC-035T, Cooling Only
50/60 Hertz
R-134a
Group: Chiller
Part Number: 331374601
Effective: June 2005
Supersedes: IMM WMC
Table of Contents
p
Introduction...........................................3
General Description........................................3
Nomenclature .................................................3
Installation.............................................4
Receiving and Handling.................................4
Location and Mounting...................................5
Water Piping...................................................5
Field Insulation...............................................7
Physical Data and Weights..............................8
Dimensions.....................................................9
Pressure Drop Curves...................................12
Relief Valves.................................................13
Electrical.......................................................14
Power Wiring................................................14
Electrical Data..............................................15
Use with On-Site Generators........................16
System Pumps...............................................17
Field Wiring Diagram...................................19
Multiple Chiller Setup..................................22
Prestart System Checklist .............................24
Operation.............................................25
Operator Responsibilities.............................25
Compressor Operation .................................25
Operating Limits:.........................................25
MicroTech II™ Control................................27
Building Automation Systems............27
Capacity Control System..............................29
Surge and Stall.............................................30
Condenser Water Temperature.....................30
Normal Unit Startup/Shutdown....................32
Annual Unit Startup/Shutdown.....................33
Maintenance........................................34
Pressure/Temperature Chart.........................34
Routine Maintenance....................................35
Repair of System..........................................36
Maintenance Schedule........................38
Service Programs................................39
Operator Schools................................39
Warranty Statement ...........................39
Unit controllers are LONMARK certified with an
o
tional LONWORKS communications module.
Manufactured in an ISO Certified Facility
Information and illustrations cover the McQuay International products at the time of publication and we reserve the right to make
®™ The following are trademarks or registered trademarks of their respective companies: BACnet from ASHRAE; Modbus from Gould, Inc;
L
ONMARK and LONWORKS from Echelon Corporation; and MicroTech II from McQuay International; Victaulic from Victaulic Company;
changes in design and construction at anytime without notice.
¤2005 McQuay International
2 Centrifugal Chillers IMM WMC-1
Introduction
General Description
The McQuay Model WMC Centrifugal Water Chiller is a complete, self-contained, automatically
controlled, fluid-chilling unit featuring dual, oil-free, magnetic bearing compressors. Each unit is
completely assembled and factory tested before shipment.
The WMC chillers are equipped with two compressors operating in parallel with a single evaporator
and single condenser.
The chillers use refrigerant R-134a that operates at a positive pressure over the entire operation
range, so no purge system is required.
The controls are pre-wired, adjusted and tested. Only normal field connections such as water piping,
relief valve piping, electric power and control interlocks are required, thereby simplifying
installation and increasing reliability. Necessary equipment protection and operating controls are
included.
All McQuay centrifugal chillers are factory-tested prior to shipment and must be commissioned by a
factory-trained McQuay service technician. Failure to follow this startup procedure can affect the
equipment warranty.
The standard limited warranty on this equipment covers parts that prove defective in material or
workmanship. Specific details of this warranty can be found in the warranty statement furnished
with the equipment.
Cooling towers used with McQuay centrifugal chillers are normally selected for condenser water
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 on optimum entering water temperature and cooling tower fan control, consult the
“Condenser Water” section on page 30.
Nomenclature
W = Water-cooled
M = Magnetic B earings
Centrifugal Compressor
W
M C 035 T
Twin Compressors
Impeller Diameter
3.5 inches
IMM WMC-1 Centrifugal Chillers 3
Installation
k
t
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.
On units with factory-installed insulation, the insulation is removed from the vessel lifting hole
(also used for transportation tie-downs) locations and are shipped loose. They should be glued in
place after the unit is finally placed. Neoprene vibration pads are also shipped loose. Check that
these items have been delivered with the unit. They are usually placed in a control panel.
If so equipped, leave the shipping skid in place until the unit is in its final position. This will aid
in handling the equipment.
Extreme care must be used when rigging the unit to prevent damage to the control panels and
refrigerant piping. See the certified dimension drawings included in the job submittal for the
center of gravity of the unit. If the drawings are not available, consult the local McQuay sales
office for assistance.
The unit can be lifted by fastening the rigging hooks to the four corners of the unit where the
rigging eyes are located (see Figure 1). Spreader bars must be used between the rigging lines to
prevent damage to the control panels, piping and electrical panels.
Figure 1, WMC Major Component Locations
Control Panel
Operator Interface
Touch Screen, OITS
Evaporator Relief Valve
Combined
Discharge Chec
Compressor #1
Suction Shutoff Valve
Compressor #2
Rigging Holes
Each Corner
Outle
Evaporator
Outlet
Inlet
Condenser
Condenser
Relief Valves
Optional Single-Point
Power Block or
Disconnect Switch
Electronic Expansion Valve
4 Centrifugal Chillers IMM WMC-1
Circuit #2
Power Panel
Circuit #1
Power Panel
Location and Mounting
Clearance
The unit must be mounted on a level concrete or steel base and must be located to provide service
clearance at one end of the unit for possible removal of evaporator and/or condenser tubes. Evaporator
and condenser tubes are rolled into the tube sheets to permit replacement if necessary. The length of the
vessel should be allowed at one end. Doors or removable wall sections can be utilized for tube clearance.
Clearance at all other points, including the top, is 3 feet (1 meter). The U.S. National Electric Code
(NEC) can require more clearance in and around electrical components (4-feet in front of electrical
panels) and must be checked.
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.
Mounting
Make sure that the floor or structural support is adequate to support the full operating weight of the
complete unit.
It is not 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 valves closed to isolate the refrigerant in the unit
condenser. Valves must remain closed until start-up by the McQuay technician.
Nameplates
There are several identification nameplates on the chiller:
• The unit nameplate is located on the Unit Control Panel. It has a Model No. XXXX and Serial No.
XXXX. Both are unique to the unit and will identify it. These numbers should be used to identify
the unit for service, parts, or warranty questions. This plate also has the unit refrigerant charge.
• Vessel nameplates are located on the evaporator and condenser. Along with other information, they
have a National Board Number (NB) and a serial number, either of which identify the vessel (but
not the entire unit).
Water Piping
Evaporator and Condenser Water Piping
All 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 size and type required.
CAUTION
Freeze Notice: Neither the evaporator nor the condenser is self-draining;
both must be blown out to help avoid damage from freezing.
The piping should 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, vibration 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 they can be required where noise and vibration are
critical.
IMM WMC-1 Centrifugal Chillers 5
Important Notes on Welding
If welding is to be performed on the mechanical or flange connections:
1. Remove the solid-state temperature sensor, thermostat bulbs and optional nozzle mounted
flow switches (if so equipped) from the wells to prevent damage to those components.
2. Properly ground the unit or severe damage to the MicroTech II unit controller can occur.
Welding should never be performed on a vessel shell or tube sheet, as this will revoke the ASME
certification.
Water pressure gauge connection taps and gauges must be provided in the field piping at the inlet
and outlet connections of both vessels for measuring the water pressure drop. The pressure drops
and flow rates for the various evaporators and condensers are job specific and the original job
documentation can be consulted for this information. Refer to the nameplate on the vessel shell
for identification.
Connections
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 connection
to maximize subcooling. The evaporator outlet is on the side of the unit with the two power
panels, regardless of which end the connections are on. See Figure 1.
CAUTION
When common piping is used for both building heating and cooling modes, care must
be taken to provide that water flowing through the evaporator cannot exceed 110°F
which can cause the relief valve to discharge refrigerant or damage controls.
Piping must be supported to eliminate weight and strain on the fittings and connections. Chilled
water piping must be adequately insulated. A cleanable 20-mesh water strainer must be installed
in both water inlet lines. Sufficient shutoff valves must be installed to permit draining the water
from the evaporator or condenser without draining the
complete system.
Figure 2, Unit-Mounted Flow Switch
Flow Switch
Chiller units must be provided with flow switches for
the evaporator and condenser. McQuay furnishes
factory-installed and wired, thermal-type flow
switches as standard equipment on WMC chillers.
They prevent the unit from starting without sufficient
water flow through the vessels. They also serve to
shut down the unit in the event that water flow is
interrupted to guard against evaporator freeze-up or
excessive discharge pressure.
Additionally, for a higher margin of protection,
normally open auxiliary contacts in the pump starters
can be wired in series with the flow switches as shown in the Field Wiring Diagram.
Cooling Towers
The condenser water flow rate must be checked to be sure that it conforms to the system design.
A tower bypass valve is required to control the minimum condenser entering temperature. Unless
the system and chiller unit are specifically designed for them, condenser bypass or variable
condenser flow is not recommended, since low condenser flow rates can cause unstable operation
and excessive tube fouling.
6 Centrifugal Chillers IMM WMC-1
Figure 3, Bypass, Mild Weather Operation
Bypass, Cold Weather Operation
Low Condenser Water Temperature Operation
When ambient wet bulb temperature are lower than design, the entering condenser water
temperature can be allowed to fall to improve chiller performance. This is especially true of an
advanced design such as the McQuay WMC that features variable compressor speed.
It is an engineering fact that as the compressor discharge pressure is reduced the amount of power
to pump a given amount of gas also is reduced. The reduction can result in significant energy
savings.
However, as with most centrifugal chiller applications, a tower bypass valve must be installed.
Figure 16 illustrates two temperature actuated tower bypass arrangements. The “Cold Weather”
scheme provides better startup under cold ambient air temperature conditions. The check valve
may be required to prevent entraining air at the pump inlet.
Minimum Condenser Water Temperatur e
The McQuay WMC centrifugal chiller will start and run with 55°F (12.8°C) entering condenser
water temperature.
It is highly recommended that the condenser water pumps cycle on and off with the unit to reduce
the possibility of refrigerant migration to the condenser. See on page 19 for wiring details.
CAUTION
Tower water treatment is essential for continued efficient and reliable unit operation.
If not available in-house, competent water treatment specialists should be contracted.
Field Insulation
If the optional factory-installation of thermal insulation is not ordered, insulation should be field
installed to reduce heat loss and prevent condensation from forming. Insulation should cover the
evaporator barrel, tube sheet, and water heads, plus the suction line to the compressor flange and
the compressor end bell opposite the suction connection.
The optional factory-installed insulation of cold surfaces includes the evaporator and nonconnection water head, suction piping, compressor inlet, and motor housing.
Insulation is UL recognized (File # E55475). It is 3/4" thick ABS/PVC flexible foam with a skin.
The K factor is 0.28 at 75°F. 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, or has been tested in accordance, with the following:
ASTM-C-177 ASTM-C-534 Type 2 UL 94-5V
ASTM-D-1056-91-2C1 ASTM E 84 MEA 186-86-M Vol. N
CAN/ULC S102-M88
IMM WMC-1 Centrifugal Chillers 7
Physical Data and Weights
Evaporator
Refrigerant-side design pressure is 200 psi (1380 kPa). Water-side is 150 psi (1034 kPa).
In the event insulation is to be field-installed, none of the cold surfaces identified above will be
factory insulated. Approximate total square footage of insulation surface required for individual
packaged chillers is tabulated by evaporator code and can be found below.
Table 1, Evaporator Physical Data
Evaporator
Code
E2209 590 (268) 38 (145) 66 (6.1) 2387 (1083) 1
E2212 790 (358) 45 (170) 90 (8.3) 2877 (1305) 1
Notes:
1. Refrigerant charge is for the entire unit and is approximate since the actual charge will depend on other variables.
Actual charge will be shown on the unit nameplate.
2. Water capacity is based on s tandard t ube configuration and standard dished heads.
Maximum
Refrigerant Charge
lb. (kg)
Evaporator
Water
Capacity, gal (L)
Insulation
Area
sq. ft. (m
Vessel
2
)
Weight
lb. (kg)
Condenser
With positive pressure systems, the pressure variance with temperature is always predictable, and
the vessel design and pressure relief protection are based upon pure refrigerant characteristics.
R-134a requires ASME vessel design, inspection and testing and uses spring-loaded pressure
relief valves. When an over pressure condition occurs, spring-loaded relief valves purge only that
refrigerant required to reduce system pressure to their set pressure, and then close.
Refrigerant-side design pressure is 200 psi (1380 kPa). Water-side design is 150 psi (1034 kPa).
Number
of Relief
Valves
Table 2, Condenser Physical Data
Condenser
Code
C2009 728 (330) 47 (147) 2130 (965) 2
C2012 971 (440) 62 (236) 2528 (1147) 2
Notes:
1. Condenser pumpdown capacity based on 90% full at 90°F.
2. Water capacity based on standard conf i guration and standard heads and can be less with lower tube counts.
3. See Relief Valves section for additional information.
Maximum
Pumpdown
Capacity lb. (kg)
Water Capacity
gal. (L)
Vessel Weight
lb. (kg)
Number of
Relief Valves
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. Model WMC
chillers are equipped with suction and discharge shutoff valves and the refrigerant charge can also
be pumped down into the evaporator.
8 Centrifugal Chillers IMM WMC-1
Dimensions
Figure 4, Dimension Drawing WMC 2 Pass Evaporator, 2 Pass Condenser
6.9
78.0
(1981.2)
4.0
(101.6)
26.5
(673.1)
35.0
(889.0)
Out
In
8.0”
QTY. 2
6.0”
QTY. 2
18.2
(462.3)
(1084.6)
12.6
(320.0)
42.7
(175.3)
01.13
QTY. 8
20.4
(518.2)
3.7 (93.9)
9.1 (231.1)
1.4 (35.5)
5.2 (132.1)
19.2 (487.7)
13.2 (335.3)
Inlet
Outlet
1.0” FPT
Relief Valves
Condenser
8.0 (203.2)
“A”
Evaporator
31.2
(792.5)
39.3
(998.2)
“B”
“C” 5.2 (132.1)
330654401 R01 Production Unit
26.5
(673.1)
8.0 (203.2)
NOTES:
1. The dimension drawing above is for standard production units. Certain early production units will have a different control panel
arrangement and a greater height dimension.
2. Left-hand connections shown. Right-hand connections are available for either vessel.
WMC Unit
A B C
9 Foot Shells 31.2 (792.4) 134.7 (3421.4) 100.1 (2542.5)
12 Foot Shells 43.7 (1109.9) 169.6 (4307.8) 134.9 (3426.5)
Dimensions Inches (mm)
IMM WMC-1 Centrifugal Chillers 9
Figure 5, Dimension Drawing WMC 3 Pass Evaporator, 2 Pass Condenser
6.9
(175.3)
12.6
(320.0)
13.2 (335.3)
13.2 (335.3)
78.0
(1981.2)
(101.6)
NOTES:
4.0
26.5
(673.1)
35.0
(889.0)
Out
In
5.0”
QTY. 2
6.0”
QTY. 2
01.13
QTY. 8
20.4
(518.2)
3.7 (93.9)
9.1 (231.1)
1.4 (35.5)
5.2 (132.1)
Inlet
1.0” FPT
Relief Valves
Condenser
8.0 (203.2)
“A”
Evaporator
31.2
(792.5)
39.3
(998.2)
“B”
“C” 5.2 (132.1)
330654401_3-Pass Evap Production Unit
26.5
(673.1)
(462.3)
Outlet
(1084.6)
8.0 (203.2)
18.2
42.7
1. The dimension drawing above is for standard production units. Certain early production units will have a different
control panel arrangement and a greater height dimension.
2. Left-hand connections shown. Right-hand connections are available for either vessel.
3. For right-hand evaporator, the inlet and outlet are reversed. That is, the inlet is on the right end and looking at the head,
the connection is on the left side.
WMC Unit
A B C
9 Foot Shells 31.2 (792.4) 134.2 (3408.7) 100.1 (2542.5)
12 Foot Shells 43.7 (1109.9) 169.1 (4295.1) 134.9 (3426.5)
Dimensions Inches (mm)
10 Centrifugal Chillers IMM WMC-1
Figure 6, Mounting/Lifti ng Weights
Corner 3 Corner 4
“A
“B”
Corner 1
Corner 2
Circuit #1
Circuit #2
Control Panel
Electric Panels
Mounting Weight, lbs (kg)
Unit Size Corner 1 Corner 2 Corner 3 Corner 4 Total
9 Ft Shells 1562 (709) 1516 (688) 1459 (662) 2350 (1067) 7887 (3581)
12 Ft Shells 2712 (1231) 2122 (963) 2161 (981) 1691 (768) 8686 (3943)
Shipping Weight, lbs (kg)
Unit Size Corner 1 Corner 2 Corner 3 Corner 4 Total “A” “B”
9 Ft Shells 1396 (634) 2249 (1021) 1305 (592) 2102 (954) 7052 (3202) 4.0 (102) 112. 0 (2845)
12 Ft Shells 2450 (1112) 1918 (871) 1965 (892) 1528 (694) 7851 (3564) 4.0 (102) 147. 0 (3734)
NOTE:
1. The block shown above is the mounting footprint, not the entire unit footprint.
Mounting Location
inch (mm)
See
Figure 4
See
Figure 4
Lifting Location
inch (mm)
See
Figure 4
See
Figure 4
2. Lifting holes in the top of the tube sheets are 2.5 inch diameter. Mounting holes in the feet are
1.125 inch diameter.
IMM WMC-1 Centrifugal Chillers 11
Pressure Drop Curves
Figure 7, Evaporator Pressure Drops
WMC Evap - Water Side Pressure Drop
90
80
70
60
50
EPD - ft
40
30
20
10
0
0 200 400 600 800 1000 1200 1400 1600 1800
EGPM - gpm
E2212-B 1 pass
E2212-B 2 pass
E2209-B 1 pass
E2209-B 2 pass
E2212-C 1 pass
E2212-C 2 pass
E2212-C 3 pass
E2209-C 1 pass
E2209-C 2 pass
E2209-C 3 pass
E2212-D 1 pass
E2212-D 2 pass
E2212-D 3 pass
E2209-D 1 pass
E2209-D 2 pass
E2209-D 3 pass
Figure 8, Condenser Pressure Drops
WMC Cond - Water Side Pressure Drop
60.0
50.0
40.0
30.0
CPD - ft
20.0
10.0
0.0
0 500 1000 1500 2000 2500
CGPM - gpm
C2012-B 1 pass
C2012-B 2 pass
C2009-B 1 pass
C2009-B 2 pass
C2012-C 1 pass
C2012-C 2 pass
C2012-C 3 pass
C2009-C 1 pass
C2009-C 2 pass
C2009-C 3 pass
12 Centrifugal Chillers IMM WMC-1
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