McQuay AGS 250B Installation Manual
Installation and Maintenance Manual
IMM A GS - 1
Group: Chiller
Part Number: 330262005
Date: November 2002
Supersedes: IMM AGS
GeneSys
AGS 230B through AGS 475B
60 Hertz, R-134a
Air-Cooled Screw Compressor Chiller
Table Of Contents
Introduction.......................................3
General Description...................................3
Nomenclature.............................................3
Inspection...................................................3
Installation and Start-up.................... 4
Handling ....................................................4
Location.....................................................5
Service Access...........................................5
Clearance Requirements............................6
Restricted Airflow......................................7
Vibration Isolators ...................................12
Lifting and Mounting Weights.................14
Chilled Water Pump .................................17
Water Piping ............................................17
System Water Volume..............................18
Variable Speed Pumping..........................18
Evaporator Freeze Protection...................18
Operating Limits:.....................................20
Flow Switch.............................................20
Water Connections...................................21
Refrigerant Charge...................................21
Glycol Solutions ......................................21
Water Flow and Pressure Drop........ 22
Physical Data...................................24
Dimensional Data............................27
Wind Baffles and Hail Guards.........29
Electrical Data................................. 31
Field Wiring.............................................31
Field Wiring Diagram......................37
Solid State Starters.......................... 38
Component Location....................... 45
Major Component Location.....................45
Power Panel.............................................47
Control Panel...........................................48
System Maintenance........................49
General ....................................................49
Compressor Maintenance........................ 49
Lubrication ..............................................49
Electrical Terminals.................................50
Condensers ..............................................50
Liquid Line Sight Glass........................... 50
Evaporator Sight Glass............................50
Lead-Lag..................................................51
Preventative Maintenance Schedule........51
Warranty Statement.........................52
Service.............................................52
Liquid Line Filter-Driers .........................52
Compressor Slide Valves.........................53
Electronic Expansion Valve.....................53
Evaporator...............................................53
Charging Refrigerant ...............................54
Charging Oil............................................55
Standard Controls....................................56
Optional Controls ....................................58
Controls, Settings and Functions .............59
Troubleshooting Chart.............................60
Periodic Maintenance Log.......................61
Our facility is ISO Certified
"McQuay" is a registered trademark of McQuay International
"Information covers the McQuay International products at the time of publication and we reserve the right to make changes in design
2 IMM AGS-1
2002 McQuay International
and construction at anytime without notice"
Introduction
N
General Description
McQuay GeneSys
refrigerating units that include the latest in engineered components arranged to provide a compact and
efficient unit. Each unit is completely assembled, factory wired, evacuated, charged, tested and
comes complete and ready for installation. Each unit consists of multiple air-cooled condenser
sections with integral subcooler sections, multiple semi-hermetic single-screw compressors, solidstate starters, a multiple circuit shell-and-tube flooded evaporator, and complete refrigerant piping.
Each compressor has an independent refrigeration circuit. Liquid line components included are
manual liquid line shutoff valves, charging ports, filter-driers, sight-glass/moisture indicators, and
electronic expansion valves. A discharge check valve is included and a compressor suction shutoff
valve is optional. Other features include compressor heaters, evaporator head heaters, automatic onetime pumpdown of refrigerant circuit upon circuit shutdown, and an advanced fully integrated
microprocessor control system.
Information on the operation of the unit and on the MicroTech II controller are in the OM AGS
manual.
air-cooled water chillers are complete, self-contained automatic
Nomenclature
A G S - XXX B
Air-Cooled
Design Vintage
Global
Rotary Screw Compressor
ominal Tons
Inspection
When the equipment is received, all items should be carefully checked against the bill of lading to
check for a complete shipment. All units should be carefully inspected for damage upon arrival. All
shipping damage must be reported to the carrier and a claim must be filed with the carrier. The unit’s
serial plate should be checked before unloading the unit to be sure that it agrees with the power
supply available. Physical damage to unit after acceptance is not the responsibility of McQuay
International.
Note: Unit shipping and operating weights are shown in the Physical Data Tables on page 24.
IMM AGS-1 3
Installation and Start-up
Note: Installation and maintenance are to be performed only by qualified personnel who are familiar
with local codes and regulations, and experienced with this type of equipment.
Sharp edges and coil surfaces are a potential injury hazard. Avoid contact with them.
Start-up by McQuayService is included on all units sold for installation within the USA and Canada
and must be performed by them to initiate the standard limited product warranty. Two-week prior
notification of start-up is required. The contractor should obtain a copy of the Start-up Scheduled
Request Form from the sales representative or from the nearest office of McQuayService.
Handling
Care should be take n to avoid rough hand ling or shock due to impact or dropping the unit. Do not
push or pull the unit.
Never allow any part of the unit to fall during unloading or moving as this can result in serious
damage.
To lift the unit, lifting tabs with 2½" (64 mm) diameter holes are provided on the base of the unit. All
lifting holes must be used when lifting the unit. Spreader bars and cables should be arranged to
prevent damage to the condenser coils or unit cabinet (see Figure 1).
Improper lifting or moving unit can result in property damage, severe
personal injury or death. Follow rigging and moving instructions carefully.
WARNING
DANGER
Figure 1, Required Lifting Method
NOTES:
1. All rigging points on a unit must be used. See page 14 through page 15 for location, and weight at
lifting points for a specific size unit.
2. Crosswise and lengthwise spreader bars must be used to avoid damage to unit. Lifting cables from the
unit mounting holes up must be vertical.
3. The number of lifting points, condenser sections, and fans can vary from this diagram.
4 IMM AGS-1
Location
Care should be taken in the location of the unit to provide proper airflow to the condenser. (See
Figure 2 on page 6 for required clearances).
Due to the shape of the condenser coils on the AGS chillers, it is recommended that the unit be
oriented so that prevailing winds blow parallel to the unit length, thus minimizing the wind effect on
condensing pressure and performance. If low ambient temperature operation is expected, it is
recommended that optional wind baffles be installed if the unit has no protection against prevailing
winds.
Using less clearance than shown in Figure 2 can cause discharge air recirculation to the condenser and
could have a significant detrimental effect on unit performance.
See Restricted Airflow beginning on page 7 for further informati on.
Service Access
Compressors, filter-driers, and manual liquid line shutoff valves are accessible on each side of the unit
adjacent to the control box. The evaporator heaters are located in each head.
Each compressor (two or three depending on unit size) has its own duplex control panel located on
the sides of the chiller between condenser coil sections. The outer control box contains the circuit
microprocessor. The box for circuit #1 also contains the unit microprocessor controller. The solid
state compressor starter, fan control and other power equipment are located in the inner panel.
The side clearance required for airflow provides sufficient service clearance.
On all AGS units the condenser fans and motors can be removed from the top of the unit. The
complete fan/motor assembly can be removed for service. The fan blade must be removed for access
to wiring terminals at the top of the motor.
WARNING
Disconnect all power to the unit while servicing condenser fan motors or compressors.
Failure to do so can cause bodily injury or death.
Do not block access to the sides or ends of the unit with piping or conduit. These areas must be open
for service access. Do not block any access to the control panels with a field-mounted disconnect
switches. In particular, be sure that the power conduit to each panel does not interfere with access to
the filter-driers located on the unit base under the panels.
IMM AGS-1 5
Clearance Requirements
Figure 2, Clearance Requirements, AGS 230B – 475B
5’-0” if open fence or 50% open wall
6’-0” if solid wall (see note 3 for pit)
5’-0” if open fence or 50% open wall
6’-0” if solid wall (see note 3 for pit)
No obstructions.
Recommended area
required for unit
operation, air flow
and maintenance
access.
10’-0” min. for
Evaporator Removal
See Note 8
See notes 2 & 4
concerning wall
height at unit sides.
Air Flow
No obstructions allowed
above unit at any height
See Note 5
Wall or
Fence
Notes:
1. Minimum side clearance between two units is 12 feet (3.7 meters).
2. Unit must not be installed in a pit or enclosure that is deeper or taller than the height of the unit
unless extra clearance is provided per note 4.
3. Minimum clearance on each side is 8 feet (2.4 meters) when installed in a pit no deeper than the
unit height.
4. Minimum side clearance to a side wall or building taller than the unit height is 6 feet (1.8 meters)
provided no solid wall above 6 feet (1.8 meters) is closer than 12 feet (3.7 meters) to the opposite
side of the unit.
5. Do not mount electrical conduits where they can block service access to compressor controls,
refrigerant driers or valves.
6. There must be no obstruction of the fan discharge.
7. Field installed switches must not interfere with service access or airflow.
8. The 10-ft. clearance required for removal of the evaporator is on the end that the evaporator
connections face. See dimension drawings on page 27 for details.
9. If the airflow clearances cannot be met, see the following page.
6 IMM AGS-1
Restricted Airflow
General
The clearances required for design operation of AGS air-cooled condensers are described in the
previous section. Occasionally, these clearances cannot be maintained due to site restrictions such as
units being too close together or a fence or wall restricting airflow, or both.
The McQuay AGS chillers have several features that can mitigate the problems attributable to
restricted airflow.
• The “W” shape of the condenser section allows inlet air for these coils to come in from both sides
and the bottom. All the coils in one "W" section serve one compressor. Every compressor
always has its own independent refrigerant circuit.
• The MicroTech II control is proactive in response to off-design conditions. In the case of
single or compounded influences restricting airflow to the unit, the microprocessor will act to
keep the compre ssor(s) running ( at reduced capacity) as l ong as possib le, rat her than all owing a
shut-off on high discharge p ressure.
Figure 3, Coil and Fan Arrangement
The following sections discuss the most common situations of condenser air restriction and give
capacity and power adjustment factors for each. Note that in unusually severe conditions, the
MicroTech II controller would adjust the unit operation to remain online until a less severe condition
is reached.
IMM AGS-1 7
Case 1, Building or Wall on One Side of One Unit
The existence of a screening wall, or the wall of a building, in close proximity to an air-cooled chiller
is common in both rooftop and ground level applications. Hot air recirculation on the coils adjoining
the wall will increase compressor discharge pressure, decreasing capacity and increasing power
consumption.
When close to a wall, it is desirable to place chillers on the north or east side of them. It is also
desirable to have prevailing winds blowing parallel to the unit’s long axis. The worst case is to have
wind blowing hot discharge air into the wall.
Figure 4, Unit Adjacent to Wall
D
H
Figure 5, Adjustment Factors
5 ft.
(1.5m)
6 ft.
(1.8m)
5 ft.
(1.5m)
6 ft.
(1.8m)
8 IMM AGS-1
Case 2, Two Units Side By Side
Two or more units sited side by side are common. If spaced closer than 12 feet (3.7 meters) it is
necessary to adjust the performance of each unit; circuits adjoining each other are affected. If one of
the two units also has a wall adjoining it, see Case 1. Add the two adjustment factors together and
apply to the unit located between the wall and the other unit.
Mounting units end to end will not necessitate adjusting performance. Depending on the actual
arrangement, sufficient space must be left between the units for access to the control panel door
opening and/or evaporator tube removal. See “Clearance” section of this guide for requirements for
specific units.
Pit or solid wall surrounds should not be used where the ambient air temperature exceeds 105°F
(40°C).
Figure 6, Two Units Side by Side
Figure 7, Adjustment Factor
IMM AGS-1 9
Case 3, Open Screening Walls
Decorative screening walls are often used to help conceal a unit either on grade or on a rooftop.
These walls should be designed such that the combination of their open area and distance from the
unit do not require performance adjustment. It is assumed that the wall height is equal to, or less than
the unit height when mounted on its base support. This is usually satisfactory for concealment. If the
wall height is greater than the unit height, see Case 4, Pit Installation.
The distance from the sides of the unit to the side walls should be sufficient for service and opening
control panel doors.
If each side wall is a different distance from the unit, the distances can be averaged, providing either
wall is not less than 8 feet (2.4 meters) from the unit. For example, do not average 4 feet and 20 feet
to equal 12 feet.
Figure 8, Open Screening Walls
Figure 9, Wall Free Area vs. Distance
6
(1.8)
to Unit - Ft. (M)
D - Distance from Wall
5
(1.5)
01020304050
% Open Wall Area
10 IMM AGS-1
Case 4, Pit/Solid Wall Installation
Pit installations can cause operating problems and great care should be exercised if they are to be used
on an installation. Recirculation and restriction can both occur. A solid wall surrounding a unit is
substantially the same as a pit and the data presented in this case should be used.
Steel grating is sometimes used to cover a pit to prevent accidental falls or trips into the pit. The
grating material and installation design must be strong enough to pr event such accidents, yet p rovide
abundant open area or serious recirculation problems will occur. Have any pit installation reviewed by
McQuay application engineers prior to installation to discuss whether it has sufficient airflow
characteristics. The installation design engineer must approve the work and is responsible for design
criteria.
Figure 10, Pit Installation
Figure 11, Adjustment Factor
IMM AGS-1 11
Vibration Isolators
Vibration isolators are recommended for all roof-mounted installations or wherever vibration
transmission is a consideration. The following section "Lifting and Mounting Weights" contains the
location of unit lifting holes and the load at each location. Mounting holes dimensions and the
bearing weight at each hole given.
The unit should be initially installed on shims or blocks at the illustrated "free height" of the isolator
that is six inches for the McQuay isolators shown. When all piping, wiring, flushing, charging, etc. is
complete, the springs should be adjusted upward to load them and to provide clearance to free the
blocks, which are then removed.
Installation of spring isolators requires flexible pipe connections and at least three feet of conduit flex
tie-ins. Piping and conduit should be supported independently from the unit so as not to stress
connections.
Figure 12, Spring Flex Isolators
Table 1, Spring Vibration Isolators, AGS 230 – 320, Part Numbers and Spring Colors
Model
AGS230
AGS250
AGS270
AGS300
AGS320
Notes:
1. The same isolators are used when the chiller is supplied with the optional copper finned condenser coils.
2. The -2- or -4- indicates that two or four springs are used in the isolator.
M1 M2 M3 M4 M5 M6 M7 M8 Kit Num ber
CP-2-28 CP-2-31 CP-2-28 CP-2-31 CP-2-31 CP-2-28 CP-2-31 CP-2-28
Green Gray Green Gray Gray Green Gray Green
CP-2-28 CP-2-31 CP-2-28 CP-2-31 CP-2-32 CP-2-31 CP-4-26 CP-2-28
Green Gray Green Gray White Gray Purple Green
CP-2-28 CP-4-26 CP-2-31 CP-2-32 CP-2-32 CP-2-31 CP-4-26 CP-2-28
Green Purple Gray White White Gray Purple Green
CP-2-28 CP-4-26 CP-2-31 CP-2-32 CP-2-32 CP-2-31 CP-4-26 CP-2-28
Green Purple Gray White White Gray Purple Green
CP-2-28 CP-4-26 CP-2-31 CP-2-32 CP-2-32 CP-2-31 CP-4-26 CP-2-28
Green Purple Gray White White Gray Purple Green
12 IMM AGS-1
Mounting Location (See Footprint Drawings Figure 13 or Figure 14)
350348101
350348102
350348103
Table 2, Spring Vibration Isolators, AGS 340 – 475, Part Numbers and Spring Colors
Model
AGS340
AGS370
AGS400
AGS420
AGS440
AGS450
AGS475
Mounting Location (See Footprint Drawings Figure 15 or Figure 16)
M1 M2 M3 M4 M5 M6
CP-2-28 CP-4-26 CP-2-28 CP-4-26 CP-4-26 CP-2-28
Green Purple Green Purple Purple Green
CP-2-28 CP-4-26 CP-2-31 CP-4-26 CP-4-26 CP-2-31
Green Purple Gray Purple Purple Gray
CP-2-28 CP-4-26 CP-2-31 CP-4-26 CP-4-27 CP-2-31
Green Purple Gray Purple Orange Gray
CP-2-31 CP-4-26 CP-2-31 CP-4-27 CP-4-27 CP-2-31
Gray Purple Gray Orange Orange Gray
CP-2-31 CP-4-26 CP-4-26 CP-4-27 CP-4-27 CP-4-26
Gray Purple Purple Orange Orange Purple
CP-2-31 CP-4-26 CP-4-26 CP-4-27 CP-4-27 CP-4-26
Gray Purple Purple Orange Orange Purple
CP-2-31 CP-4-26 CP-4-26 CP-4-27 CP-4-27 CP-4-26
Gray Purple Purple Orange Orange Purple
Continued
Model
AGS340
AGS370
AGS400
AGS420
AGS440
AGS450
AGS475
Notes:
M7 M8 M9 M10 M11 M12 Kit Number
CP-4-26 CP-2-28 CP-2-31 CP-2-27 CP-2-27 CP-2-27
Purple Green Gray Orange Orange Orange
CP-4-26 CP-2-28 CP-2-31 CP-2-28 CP-2-31 CP-2-28
Purple Green Gray Green Gray Green
CP-4-26 CP-2-31 CP-2-31 CP-2-28 CP-2-31 CP-2-28
Purple Gray Gray Green Gray Green
CP-4-26 CP-2-31 CP-2-31 CP-2-28 CP-2-31 CP-2-28
Purple Gray Gray Green Gray Green
CP-4-26 CP-2-31 CP-2-31 CP-2-28 CP-2-31 CP-2-28
Purple Gray Gray Green Gray Green
CP-4-26 CP-2-31 CP-2-31 CP-2-28 CP-2-31 CP-2-28
Purple Gray Gray Green Gray Green
CP-4-26 CP-2-31 CP-2-31 CP-2-28 CP-2-31 CP-2-28
Purple Gray Gray Green Gray Green
1. The same isolators are used when the chiller is supplied with the optional copper finned condenser coils.
2. The -2- or -4- indicates that two or four springs are used in the isolator.
Mounting Location (Table Continued)
350348104
350348105
350348106
350348107
350348108
Table 3, Neoprene-in-Shear Isolators, AGS 230 – 320, Part Numbers
Model
AGS230 4-RED 4-RED 4-RED 4-RED 4-RED 4-RED 4-RED 4-RED 350348201
AGS250 4-RED 4-RED 4-RED 4-RED 4-GREEN 4-RED 4-RED 4-RED 350348202
AGS270 4-RED 4-RED 4-RED 4-GREEN 4-GREEN 4-RED 4-RED 4-RED
AGS300 4-RED 4-RED 4-RED 4-GREEN 4-GREEN 4-RED 4-RED 4-RED
AGS320 4-RED 4-RED 4-RED 4-GREEN 4-GREEN 4-RED 4-RED 4-RED
Note:
M1 M2 M3 M4 M5 M6 M7 M8 Kit Number
1. The same isolators are used when the chiller is supplied with the optional copper finned condenser coils.
Mounting Location (See Footprint Drawings Figure 13 or Figure 14)
350348203
Table 4, Neoprene-in-Shear Isolators, AGS 340 – 475, Part Numbers
Model
AGS340 4-RED 4-RED 4-RED 4-RED 4-RED 4-RED
AGS370 4-RED 4-GREEN 4-RED 4-GREEN 4-GREEN 4-RED
AGS400 4-RED 4-GREEN 4-RED 4-GREEN 4-GREEN 4-RED
AGS420 4-RED 4-GREEN 4-RED 4-GREEN 4-GREEN 4-RED
AGS440 4-RED 4-GREEN 4-RED 4-GREEN 4-GREEN 4-RED
AGS450 4-RED 4-GREEN 4-RED 4-GREEN 4-GREEN 4-RED
AGS475 4-RED 4-GREEN 4-RED 4-GREEN 4-GREEN 4-RED
Mounting Location (See Footprint Drawings Figure 15 or Figure 16)
M1 M2 M3 M4 M5 M6
Table continued on following page for M7 thr ough M12 plus kit numbers .
IMM AGS-1 13
Model
M7 M8 M9 M10 M11 M12 Kit Number
Mounting Location (Table Continued)
AGS340 4-RED 4-RED 4-RED 4-RED 4-RED 4-RED 350348204
AGS370 4-GREEN 4-RED 4-RED 4-RED 4-RED 4-RED
AGS400 4-GREEN 4-RED 4-RED 4-RED 4-RED 4-RED
AGS420 4-GREEN 4-RED 4-RED 4-RED 4-RED 4-RED
AGS440 4-GREEN 4-RED 4-RED 4-RED 4-RED 4-RED
AGS450 4-GREEN 4-RED 4-RED 4-RED 4-RED 4-RED
AGS475 4-GREEN 4-RED 4-RED 4-RED 4-RED 4-RED
Note:
1. The same isolators are used when the chiller is supplied with the optional copper finned condenser coils.
Lifting and Mounting Weights
Figure 13, AGS 230B – AGS 250B Lifting and Mounting Locations
350348205
88.0
(2235.2)
NOTE: Evaporator connections point left.
Figure 14, AGS 270B - AGS 320B Lifting and Mounting Locations
2 (51)
Typical Spacing
for Isolator
Mounting (8)
2 (51)
Typical Spacing
for Isolator
Mounting (8)
88.0
(2235.2)
14 IMM AGS-1
Table 5, AGS 230B - AGS 320B Lifting and Mounting Weights
AGS
Model
Lbs. 2183 3043 2563 2563 3043 2183 1683 2325 1681 2322 2322 1681 2325 1683
230B
250B
270B
300B
320B
(kg) 991 1382 1164 1164 1382 991 764 1055 763 1054 1054 763 1055 764
Lbs. 2183 3043 2700 2704 3374 2509 1683 2325 1681 2322 2693 2018 2421 1814
(kg) 991 1382 1226 1228 1532 1139 764 1055 763 1054 1223 916 1099 824
Lbs. 2509 3374 2841 2841 3374 2509 1814 2421 2018 2693 2693 2018 2421 1814
(kg) 1139 1532 1290 1290 1532 1139 824 1099 916 1223 1223 916 1099 824
Lbs. 2520 3383 2871 2871 3383 2520 1821 2425 2043 2721 2721 2043 2425 1821
(kg) 1144 1536 1304 1304 1536 1144 827 1101 928 1235 1235 928 1101 827
Lbs. 2550 3407 2956 2956 3407 2550 1838 2435 2111 2797 2797 2111 2435 1838
(kg) 1158 1547 1342 1342 1547 1158 834 1106 958 1270 1270 958 1106 834
NOTES:
1. Lifting tabs with 2 ½ in. (63.5 mm) holes at location "L" on side of base rail.
2. 1 in. (25.4 mm) mounting holes at location "M" on bottom of base rails.
Lifting Weight for Each Point lb (kg) Mounting Loads for Each Point lb. (kg)
L1 L2 L3 L4 L5 L6 M1 M2 M3 M4 M5 M6 M7 M8
Figure 15, AGS 340B – AGS 400B Lifting and Mounting Locations
NOTE: Evaporator connections point left.
Figure 16, AGS 420B - AGS 475B Lifting and Mounting Locations
2 (51)
Typical Spacing
for Isolator
Mounting (8)
88.0
(2235.2)
88.0
(2235.2)
2 (51)
Typical Spacing
for Isolator
Mounting (8)
IMM AGS-1 15
Table 6, AGS 340B - AGS 475B Lifting Weights
Lifting Weight for Each Point lb (kg)
340B
370B
400B
420B
440B
450B
475B
AGS
Model
lbs 2312 3173 2681 2681 3352 2473 3192 2880
(kg) 1050 1441 1217 1217 1522 1123 1449 1307
lbs 2449 3296 2951 2951 3617 2742 3519 3216
(kg) 1112 1496 1340 1340 1642 1245 1597 1460
lbs 2449 3296 3119 3117 3917 3044 3519 3216
(kg) 1112 1496 1416 1415 1778 1382 1597 1460
lbs 2751 3596 3285 3285 3917 3044 3519 3216
(kg) 1249 1633 1491 1491 1778 1382 1597 1460
lbs 2783 3624 3361 3361 3945 3076 3519 3216
(kg) 1263 1645 1526 1526 1791 1396 1597 1460
lbs 2783 3624 3361 3361 3945 3076 3519 3216
(kg) 1263 1645 1526 1526 1791 1396 1597 1460
lbs 2783 3624 3361 3361 3945 3076 3519 3216
(kg) 1263 1645 1526 1526 1791 1396 1597 1460
L1 L2 L3 L4 L5 L6 L7 L8
Table 7, AGS 340B - AGS 475B Mounting Weights
Mounting Loads for Each Point lb. (kg)
340B
370B
400B
420B
440B
450B
475B
AGS
Model
lbs 1798 2442 1787 2426 2426 1787 2442 1798 1726 1557 1645 1484
lbs 1885 2511 1981 2638 2638 1981 2511 1885 1973 1803 1867 1706
lbs 1885 2511 1981 2638 3055 2357 2562 1977 1973 1803 1867 1706
lbs 1977 2562 2357 3055 3055 2357 2562 1977 1973 1803 1867 1706
lbs 1999 2579 2425 3128 3128 2425 2579 1999 1973 1803 1867 1706
lbs 1999 2579 2425 3128 3128 2425 2579 1999 1973 1803 1867 1706
lbs 1999 2579 2425 3128 3128 2425 2579 1999 1973 1803 1867 1706
M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11 M12
kg 816 1109 811 1101 1101 811 1109 816 784 707 747 674
kg 856 1140 899 1198 1198 899 1140 856 896 819 847 775
kg 856 1140 899 1198 1387 1070 1163 897 896 819 847 775
kg 897 1163 1070 1387 1387 1070 1163 897 896 819 847 775
kg 908 1171 1101 1420 1420 1101 1171 908 896 819 847 775
kg 908 1171 1101 1420 1420 1101 1171 908 896 819 847 775
kg 908 1171 1101 1420 1420 1101 1171 908 896 819 847 775
16 IMM AGS-1
Chilled Water Pump
It is required that the chilled water pumps' starter be wired to and controlled by the chiller's
microprocessor. The controller will energize the pump whenever at least one circuit on the chiller is
enabled to run, whether there is a call for cooling or not. The pump will also be energized when the
controller senses a near-freezing temperature at the chiller outlet sensor to assist in cold weather
freeze protection. Connection points are shown in Figure 24 on page 37.
Water Piping
Due to the variety of piping practices, it is advisable to follow the recommendations of local
authorities. They can supply the installer with the proper building and safety codes required for a
safe and proper installation.
NOTE: Chilled water piping must enter and exit the unit platform between the base rail and the
bottom of the condenser coil in the approximately 30-inch width shown on Figure 20 and Figure 21.
The piping should be designed with a minimum number of bends and changes in elevation to keep
system cost down and performance up. It should contain:
1. Vibration eliminators to reduce vibration and noise transmission to the building.
2. Shutoff valves to isolate the unit from the piping system during unit servicing.
3. Manual or automatic air vent valves at the high points of the system and drains at the low parts in
the system. The evaporator should not be the highest point in the piping system.
4. Some means of maintaining adequate system water pressure (i.e., expansion tank or regulating
valve).
5. Water temperature and pressure indicators located at the unit to aid in unit servicing.
6. A strainer to remove foreign matter from the water before it enters the pump. The strainer should
be placed far enough upstream to prevent cavitation at the p ump inlet (co nsult p ump
manufacturer for recommendations). The use of a strainer will prolong pump life and help
maintain high system performance levels.
NOTE: A strainer must also be placed in the supply water line just prior to the inlet of the
evaporator. This will aid in preventing foreign material from entering the evaporator and causing
damage or decreasing its performance. Care must also be exercised if welding pipe or flanges to
the evaporator connections to prevent any weld slag from entering the vessel.
7. Any water piping to the unit must be protected to prevent freeze-up if below freezing
temperatures are expected. See page 18 for further information on freeze protection.
CAUTION
If a separate disconnect is used for the 115V supply to the unit, it should power t he entire
control circuit, not just the evaporator heaters. It should be clearly marked so that it is not
accidentally shut off during cold seasons. Freeze damage to the evaporator could result. If
the evaporator is drained for winter freeze protection, the heaters must be de-energized to
prevent burnout.
8. If the unit is used as a replacement chiller on a previously existing piping system, the system
should be thoroughly flushed prior to unit installation and then regular chilled water ana l ysis and
chemical water treatment is recommended immediately at equipment start-up.
9. The total water quantity in the system should be sufficient to prevent frequent "on-off" cycling.
For air conditioning systems, system gallons equal to 4 times the flow rate is recommended.
IMM AGS-1 17
10. In the event glycol is added to the water system as a late addition for freeze protection, recognize
that the refrigerant suction pressure will be lower, cooling performance less, and water side
pressure drop greater. If the percentage of glycol is large, or if propylene is employed in lieu of
ethylene glycol, the added pressure drop and loss of performance could be substantial.
11. For ice making or glycol operation, a different freezestat pressure value can be desired. The
freezestat setting can be manually changed through the MicroTech II controller.
A preliminary leak check should be made prior to insulating the water piping and filling the system.
Piping insulation should include a vapor barrier to prevent moisture condensation and possible
damage to the building structure. It is important to have the vapor barrier on the outside of the
insulation to prevent condensation within the insulation on the cold surface of the pipe.
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, improper motor cooling, shortened equipment life
and other undesirable consequences.
For normal comfort cooling applications where the cooling load changes relatively slowly, we
recommend a minimum system volume of four minutes times the flow rate (gpm). For example, if the
design chiller flow rate is 800 gpm, we recommend a minimum system volume of 3200 gallons (800
gpm x 4 minutes).
For process applications where the cooling load can change rapidly, additional system water volume
is needed. A process example would be a quenching tank. The load would be very stable until the
hot material is immersed in the water tank. Then, the load would increase drastically. For this type of
application, system volume can need to be increased.
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.
Variable Speed Pumping
Variable water flow involves changing the water flow through the evaporator as the load changes.
McQuay chillers are designed for this duty, pro vided that the rate of change in water flow is slow and
the minimum and maximum flow rates for the vessel are not exceeded.
The recommended maximum change in water flow is 10 percent of the change per minute.
The water flow through the vessel must remain be tween the minimum and maximum values listed on
page 23. If flow drops below the minimum allowable, large reductions in heat transfer can occur. If
the flow exceeds the maximum rate, excessive pressure drop and tube erosion can occur.
Evaporator Freeze Protection
Flooded evaporators are popular with chiller manufacturers because of their inherent high efficiency.
Care must be exercised in the equipment design and in the operation of these evaporators to prevent
freezing between 32°F and -20°F.
For protection down to 0°F (-18°C), the AGS chillers are equipped with thermostatically controlled
evaporator heaters that help protect against freeze-up provided the chiller goes through its normal
pumpdown cycle. Several occurrences can prevent this normal pumpdown from happening:
1. A power failure will prevent pumpdown and there is a potential for freezing outdoor equipment in
systems using 100 percent water as the chilled fluid.
18 IMM AGS-1
2. Unit shutdown due to a fault will cause immediate compressor shutdown without the pumpdown
cycle. This situation can be remedied by correcting the fault, restarting the unit, and allowing it
to go through its normal shutdown pumpdown.
NOTE: The heaters come from the factory connected to the control power circuit. The control power
can be rewired to a separate 115V supply (do not wire directly to the heater). If this is done, the
disconnect switch should be clearly marked to avoid accidental deactivation of the heater during
freezing temperatures. Exposed chilled water piping also requires protection.
It is required that the chilled water pump’s starter be wired to, and controlled by, the chiller's
microprocessor. The controller will energize the pump whenever at least one circuit on the chiller is
enabled to run, whether there is a call for cooling or not. The pump will also be energized when the
controller senses a near-freezing temperature at the chiller outlet sensor to assist in cold weather
freeze protection. Connection points are shown in Figure 24 on page 37.
For additional protection to -20°F (-29°C) and to protect against the consequences described above, it
is recommended that at least one of the following procedures be used during periods of sub-freezing
temperatures:
1. Addition of a concentration of a glycol anti-freeze with a freeze point 15 degrees below the
lowest expected temperature. This will result in decreased capacity and increased pressure drop.
Note: Do not use automotive grade antifreezes as they contain inhibitors harmful to chilled water
systems. Only use glycols specifically designated for use in building cooling systems.
2. Draining the water from outdoor equipment and piping and blowing the chiller tubes dry from the
chiller. Do not energize the chiller heater when water is drained from the vessel.
CAUTION
If fluid is absent from the evaporator, the evaporator heater must be de-energized to avoid
burning out the heater and causing damage from the high temperatures.
3. Providing opera tion o f the chilled water pump, circ ulating water thro ugh the chille d water system
and through the evaporator. The chiller micropr oce ssor will automatically start up the pump if so
wired.
Table 8, Freeze Protection
Temperature
°F (°C)
20 (6.7)16181112
10 (-12.2) 25 29 17 20
0 (-17.8) 33 36 22 24
-10 (-23.3) 39 42 26 28
-20 (-28.9) 44 46 30 30
-30 (-34.4) 48 50 30 33
-40 (-40.0) 52 54 30 35
-50 (-45.6) 56 57 30 35
-60 (-51.1) 60 60 30 35
Notes:
1. These figures are examples only and cannot be appropriate to every situation. Generally, for an extended margin of
protection, select a temperature at leas t 10
should be adjusted for solutions less t han 30% glycol.
2. Glycol of less than 20% concentration is not recommended bec aus e of t he pot ent ial for bacterial growth and loss of
heat transfer efficiency.
Ethylene Glycol Propylene Glycol Ethylene Glycol Propylene Glycol
For Freeze Protection For Burst Protection
Percent Volume Glyc ol Concentration Required
°F lower than the expected lowest ambient temperature. Inhibitor levels
IMM AGS-1 19
Operating Limits:
Maximum standby ambient temperature, 130°F (55°C)
Maximum operating ambient temperature, 115°F (46°C), or 125°F (52°C) with optional high ambient
package
Minimum operating ambient temperature (standard), 35°F (2°C)
Minimum operating ambient temperature (optional low-ambient control), 0°F (-18°C)
Leaving chilled water range, 38°F to 50°F (3°C to 10°C)
Leaving chilled fluid range (with anti-freeze), 20°F to 50°F (7°C to 10°C)
Operating Delta-T range, 6 degrees F to 16 degrees F (10.8 C to 28.8 C)
Maximum operating inlet fluid temperature, 66°F (19°C)
Maximum startup inlet fluid temperature, 90°F (32°C)
Maximum non-operat i ng inlet fluid temperature, 100°F (38°C)
NOTE: Contact the local McQuay sales office for operation outside of these limits.
Flow Switch
A water flow switch must be mounted in the leaving chilled water line to prove that there is adequate
water flow to the evaporator before the unit can start. It also serves to shut down the unit in the event
that water flow is interrupted in order to guard against evaporator freeze-up.
A flow switch is available from McQuay under ordering number 017503300. It is a paddle-type
switch and adaptable to any pipe size from 1" (25mm) to 8" (203mm) nominal.
Certain minimum flow rates are required to close the switch and are listed in Table 9. Installation
should be as shown in Figure 17.
Electrical connections in the unit control center should be made at terminals 60 and 67. The normally
open contacts of the flow switch should be wired between these two terminals. Flow switch contact
quality must be suitable for 24 VAC, low current (16ma). Flow switch wire must be in separate
conduit from any high voltage conduc tors (115 VAC and higher) and have an insul ation r ating of 6 00
volts.
Figure 17, Flow Switch
1 1/4" (32mm) pipe
dia. min. after switch
Flow direction marked
on switch
1" (25mm) NPT flow
switch connection
Tee
1 1/4" (32mm) pipe
dia. min. before switch
Table 9, Switch Minimum Flow Rates
NOMINAL PIPE
SIZE
INCHES (MM)
5 (127) 58.7 (3.7)
6 (152) 79.2 (5.0)
8 (203) 140 (8.8)
Note: Water pressure differential switches are not recommended for
outdoor applications.
MINIMUM REQUIRED FLOW
TO ACTIVATE SWITCH
GPM (LPS)
20 IMM AGS-1
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