Test Procedures............................................79
2AGZ 030A through 065AIOM 686
Introduction
General Description
McQuay Air-Cooled Global water chillers are complete, self-contained automatic refrigerating units.
Every unit is completely assembled, factory wired, charged, and tested. Each unit consists of twin AirCooled condensers with integral subcooler sections, multiple tandem scroll compressors, replaceable
tube dual circuit shell-and-tube evaporator, and complete refrigerant piping. Liquid line components
include manual liquid line shutoff valves, sight-glass/moisture indicators, solenoid valves, and double
diaphragm hydraulic element thermal expansion valves. Other features include compressor crankcase
heaters, an evaporator heater for chilled water freeze protection, limited pumpdown during “on” or
“off” periods, compressor lead-lag switch to alternate the compressor starting sequence, and sequenced
starting of compressors.
automatic operation. Condenser fan motors are fused in all three phases and started by their own
three-pole contactors. Compressors are not fused but may be protected by optional circuit breakers.
Inspection
Check all items carefully against the bill of lading. Inspect all units for damage upon arrival. Report
shipping damage and file a claim with the carrier. Check the unit name plate before unloading, making
certain it agrees with the power supply available. McQuay is not responsible for physical damage after
unit leaves the factory.
The electrical control center includes all safety and operating controls necessary for dependable
Note: Unit shipping and operating weights are available in the Physical Data tables
beginning on page 13.
IOM 686AGZ 030A through 065A3
Installation
Note: Installation is to be performed by qualified personnel who are familiar with local
codes and regulations.
WARNING
Sharp edges and coil surfaces are a potential hazard. Avoid contact with them.
Handling
Be careful to avoid rough handling of the unit. Do not push or pull the unit from anything other than
the base. Block the pushing vehicle away from the unit to prevent damage to the sheet metal cabinet
and end frame (see Figure 1).
To lift the unit, 2 1/2" (64mm) diameter lifting holes are provided in the base of the unit. Arrange
spreader bars and cables to prevent damage to the condenser coils or cabinet (see Figure 2).
Figure 1, Suggested pushing arrangement
Blocking is required
across full width
Figure 2, Suggested lifting arrangement
Number of fans may vary
Spreader Bars
recommended
(use caution)
4AGZ 030A through 065AIOM 686
from this diagram. The
lifting method will remain
the same
These rigging holes
must be used.
Location
Unit Placement
AGZ units are for outdoor applications and can be mounted on a roof or ground level. Set units on a
solid and level foundation. For roof mounted applications, install the unit on a steel channel or I-beam
frame to support the unit above the roof. For ground level applications, install the unit on a
substantial base that will not settle. A one piece concrete slab with footings extended below the frost
line is recommended. Be sure the foundation is level (within 1/2” [13 mm] over its length and width).
The foundation must support the operating weights listed in the Physical Data tables beginning on page
13.
On ground level applications protect fins against vandalism using the optional coil guards or by
erecting a screen fence. The fence must allow free flow of air to the condenser coil for proper unit
operation.
Clearances
The flow of air to and from the condenser coil must not be limited. Restricting air flow or allowing
air recirculation will result in a decrease in unit performance and efficiency. There must be no
obstruction above the unit that would deflect discharge air downward where it could be recirculated
back to the inlet of the condenser coil. The condenser fans are propeller type and will not operate with
ductwork on the fan outlet.
Install the unit with enough side clearance for air entrance to the coil and for servicing. Provide
service access to the evaporator, compressors, electrical control panel and piping components as
shown in Figure 3.
Do not allow debris to accumulate near the unit. Air movement may draw debris into the
condenser coil causing air starvation. Give special consideration to low ambient operation where
snow can accumulate. Keep condenser coils and fan discharge free of snow or other obstructions to
permit adequate airflow.
Sound Isolation
The ultra-low sound levels of the AGZ chiller is suitable for most applications. When additional
sound reduction is necessary, locate the unit away from sound sensitive areas. Avoid locations beneath
windows or between structures where normal operating sounds may be objectionable. Reduce
structurally transmitted sound by isolating water lines, electrical conduit and the unit itself. Use wall
sleeves and rubber isolated piping hangers to reduce transmission of water or pump noise into
occupied spaces. Use flexible electrical conduit to isolate sound through electrical conduit. Spring
isolators are effective in reducing the low amplitude sound generated by reciprocating compressors
and for unit isolation in sound sensitive areas.
Service Access
Each end of the unit must be accessible after installation for periodic service. Compressors, filterdriers, and manual liquid line shutoff valves are accessible. High pressure control is located in the
control panel when using the Global UNT controller, and on the compressor when using the
MicroTech controller. Low pressure, and motor protector controls are on the compressor. Most other
operational, safety and starting controls are located in the unit control box.
The condenser fan and motors can be removed from the top of the unit.
IOM 686AGZ 030A through 065A5
Vibration Isolators
Vibration isolators are recommended for all roof mounted installations or wherever vibration
transmission is a consideration.
lists isolator loads and type. Table 2 lists spring isolator part numbers for all unit sizes. See
Dimensional Data for dimensions required to secure each isolator to the mounting surface.
Figure 3, Clearance requirements
6AGZ 030A through 065AIOM 686
The spring flex isolators are white type CP2-32, McQuay part number 047792932. A total of four per
unit is required.
Figure 4, Isolator Locations
Table 1 , Isolator Loads at each Mounting Location with Aluminum Fins
Local authorities can supply the installer with the proper building and safety codes required for safe
and proper installation.
Install piping with minimum bends and changes in elevation to minimize pressure drop. Consider
the following when installing water piping:
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.
IOM 686AGZ 030A through 065A7
3. Manual or automatic air vent valves at the high points of the system. Install drains at the lowest
points in the system.
4. A means of maintaining adequate system water pressure (expansion tank or regulating valve).
5. Temperature and pressure indicators located at the unit to aid in unit servicing.
6. A strainer or other means of removing foreign matter from the water before it enters the pump.
Place the strainer far enough upstream to prevent cavitation at the pump inlet (consult pump
manufacturer for recommendations). The use of a strainer will prolong pump life and keep
system performance up.
7. Place a strainer in the water line just before the inlet of the evaporator. This will help prevent
foreign material from entering and decreasing the performance of the evaporator.
CAUTION
If separate disconnect is used for the 115V supply to the evaporator heating cable, mark
the disconnect clearly to ensure disconnect is not accidentally shut off during cold seasons.
8. The shell-and-tube evaporator has a thermostat and heating cable to prevent freeze-up down to 20°F (-29°C). It is suggested that the heating cable be wired to a separate 110V supply circuit.
As shipped from the factory, the heating cable is wired to the control circuit. All water piping to
the unit must also be protected to prevent freezing.
9. If the unit is used as a replacement chiller on a previously existing piping system, flush the system
thoroughly before unit installation. Regular water analysis and chemical water treatment for the
evaporator loop is recommended immediately at equipment start-up.
10. The total water volume in the system should be sufficient to prevent frequent “on-off” cycling.
Turnover rate should not be less than 15 minutes for normal variable cooling loads. Turnover rate
for process cooling or a constant load, should not be less than 6 minutes.
11. When glycol is added to the water system for freeze protection, the refrigerant suction pressure
will be lower, cooling performance less, and water side pressure drop greater. If the percentage of
glycol is high, or if propylene is used instead of ethylene glycol, the added pressure drop and loss
of performance could be substantial. Reset the freezestat and low leaving water alarm
temperatures. The freezestat is factory set to default at 36°F (2.2°C). Reset the freezestat setting
to approximately 4 to 5 degrees F (2.3 to 2.8 degrees C) below the leaving chilled water setpoint
temperature. See the section titled “Glycol Solutions” for additional information concerning
glycol.
12. Perform a preliminary leak check before insulating the piping and filling the system.
13. Piping insulation should include a vapor barrier to prevent condensation and possible damage to
the building structure.
Figure 5, Typical field evaporator water piping
8AGZ 030A through 065AIOM 686
Flow Switch
Mount a water flow switch in either the entering or leaving water line to shut down the unit when
water flow is interrupted.
A flow switch is available from McQuay (part number 0017503300). It is a “paddle” type switch
and adaptable to any pipe size from 3” (76mm) to 8” (203mm) nominal. Certain minimum flow rates
are required to close the switch and are listed in Table 3. Installation should be as shown in Figure 6.
Connect the normally open contacts of the flow switch in the unit control center at terminals 5 and 6.
There is also a set of normally closed contacts on the switch that can be used for an indicator light or
an alarm to indicate when a “no flow” condition exists. Freeze protect any flow switch that is installed
outdoors.
NOTE: Differential pressure switches are not recommended for outdoor installation.
Bring water piping to the evaporator through the side between the vertical supports.
Refrigerant Charge
All units are designed for use with R-22 and other refrigerants. See nameplate for specific refrigerant
used. Units are shipped with an operating charge. The operating charge
(using R-22) for each unit is shown in the Physical Data tables beginning on page 13.
Superheat and Subcooling
For optimum operation, set the evaporator superheat for 8 - 12°F (4.4 - 6.6°C) and condenser
subcooling (at the liquid shutoff valves) to 15°F (8.3°C).
IOM 686AGZ 030A through 065A9
Note: The procedure
does not specify the
type of glycol. Use
the derate factors
found in Table 4 for
corrections when
using ethylene glycol
and those in Table 5
for propylene glycol.
Glycol Solutions
The system glycol capacity, glycol solution flow rate in GPM, and pressure drop through the cooler
may be calculated using the following formulas and table.
1. Capacity -- Find the reduced capacity by multiplying the chiller’s capacity with water by the
capacity correction factor C.
2. Flow -- To determine evaporator gpm (or Delta-T) knowing Delta-T (or gpm) and capacity:
×
Glycol GPM (from table)=
24capacity glycol
DeltaT
For Metric Applications -- To determine evaporator L/s (or Delta-T) knowing Delta-T (or L/s)
and kW:
Glycol L / s(from table)=
4.18
kW
×−
DeltaT
3. Pressure drop -- To determine pressure drop through the evaporator, when using glycol, enter the
water pressure drop curve on page 12 at the actual glycol GPM. Multiply the water pressure drop
by PD correction factor from Table 4 or Table 5 to obtain corrected glycol pressure drop.
4. To determine the unit's power consumption when using glycol, multiply the water system kW by
factor kW.
Test coolant with a clean, accurate glycol solution hydrometer (similar to that found in service
stations) to determine the freezing point. Obtain percent glycol from the freezing point table below.
On glycol applications it is normally recommended by the supplier that a minimum of 25% solution by
weight be used for protection against corrosion.
()
−
×
Flow
×
G
CAUTION
Do not use an automotive grade antifreeze. Industrial grade glycols must be used.
Automotive antifreeze contains inhibitors which will cause plating on the copper tubes within
the chiller evaporator. The type and handling of glycol used must be consistent with local
codes.
Water Volume, Gallons, (L)9.1 (34.5)9.1 (34.5)12.8 (48.5)
Drain - NPT int, In. (mm).375 (9.5).375 (9.5).375 (9.5)
Vent - NPT int, In. (mm).375 (9.5).375 (9.5).375 (9.5)
(2032 x
2121)
(3103)
(2032 x
2121)
450 (3103)450
(2032 x
2121)
(3103)
(2032 x
2121)
450
(3103)
(2032 x
2121)
450
(3103)
IOM 686AGZ 030A through 065A15
Electrical Data
Field Wiring
Internal power wiring to the compressors for single and multiple point option are different.
Field wiring must be installed according to unit wiring diagram.
Wiring must comply with all applicable codes and ordinances. Warranty is void if wiring is not in
accordance with specifications. Copper wire is required for all power lead terminations at the unit.
Aluminum or copper can be used for all other wiring.
AGZ units have internal power wiring for single point power connection. A single large power
terminal block is provided and wiring within the unit is sized in accordance with the National
Electrical Code. A single field supplied fused disconnect is required. An optional factory mounted
transformer may be installed.
If the evaporator heater is on a separate disconnect switch from the main unit power supply, the
unit may be shut down without defeating the freeze protection provided by the cooler heater.
Table 10, AGZ030A - 065A, 60 Hz, Single Point Power Electrical Data
1. Unit wire size ampacity (MCA) is equal to 125% of the largest compressor-motor RLA plus
100% of RLA of all other loads in the circuit including the control transformer.
2. If the control transformer option is furnished, no separate 115v power is required.
3. If a separate 115V power supply is used for the control circuit, then the wire sizing amps is 10
amps for all unit sizes.
4. Recommended power lead wire sizes for 3 conductors per conduit are based on 100% conductor
ampacity in accordance with NEC. Voltage drop has not been included. Therefore, it is
recommended that power leads be kept short. All terminal block connections must be made with
copper (type THW) wire.
5. “Recommended Fuse Sizes” are selected at approximately 150% to 175% of the largest
compressor RLA, plus 100% of all other loads in the circuit.
6. “Maximum Fuse Sizes” are selected at approximately 225% of the largest compressor RLA, plus
100% of all other loads in the circuit.
7. The recommended power lead wire sizes are based on an ambient temperature of 86° F.
Ampacity correction factors must be applied for other ambient temperatures. Refer to the
National Electrical Code Handbook.
Voltage Limitations:
Within ± 10 percent of nameplate rating
Notes for “Compressor and Condenser Fan Amp Draw”:
1. Compressor RLA values are for wiring sizing purposes only but do not reflect normal operating
current draw at rated capacity. If unit is equipped with SpeedTrol condenser fan motors, the first
motor on each refrigerant circuit is a single phase, 1hp motor, with a FLA of 2.8 amps at 460
volts, 5.6 amps at 208, 230, 380, and 575 volts.
2. Compressor LRA for reduced inrush start are for the first winding only. If the unit is equipped
with SpeedTrol motors, the first motor is a single phase, 1 hp motor, with a LRA of 7.3 amps at
460 volts, 14.5 amps at 208, 230, 380, and 575 volts.
Notes for “Field Wiring Data”
1. Requires a single disconnect to supply electrical power to the unit. This power must be fused.
2. All field wiring to unit power block or optional non-fused disconnect switch must be copper.
3. All field wire size values given in table apply to 75° C rated wire per NEC.
18AGZ 030A through 065AIOM 686
Figure 8, Typical Field Wiring with Global UNT Controller