"McQuay" is a registered trademarks of McQuay International
"Information covers the McQuay International products at the time of publication and we reserve the right to make changes in
design and construction at anytime without notice"
2IOMM ALS-3
Initial Issue January 1998
2001 McQuay International
Introduction
Design Vintage
General Description
McQuay air-cooled water chillers are complete, self-contained automatic refrigerating units that
include the latest in engineering 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, except for remote evaporator models. Each unit consists of multiple air-cooled
condensers with integral subcooler sections, multiple accessible semi-hermetic single-screw
compressors, solid-state starters, multiple circuit shell-and-tube evaporator, and complete refrigerant
piping. Liquid line components included are manual liquid line shutoff valves, charging valves, filterdriers, liquid line solenoid valves, sightglass/moisture indicators, and electronic expansion valves.
Compressor suction and discharge shutoff valves are included. Other features include compressor
heaters, an evaporator heater for low ambient water freeze protection, automatic one time pumpdown
of refrigerant circuit upon circuit shutdown, and an advanced fully integrated microprocessor control
system.
Nomenclature
A L S - XXX C
Air-Cooled
Liquid Oil Injected
Rotary Screw Compressor
Inspection
When the equipment is received, all items should be carefully checked against the bill of lading to
insure 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 available in the Physical Data Tables.
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. 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.
Nominal Tons
CAUTION
IOMM ALS-33
Handling
Care should be taken to avoid rough handling or shock due to impact or dropping the unit. Do not
push or pull the unit from anything other than the base, and block the pushing vehicle away from the
unit to prevent damage to the sheet metal cabinet and end frame (see Figure 1).
Never allow any part of the unit to fall during unloading or moving as this may result in serious
damage.
To lift the unit, 2½ “ (64 mm) diameter lifting holes are provided in the base of the unit. Spreader bars
and cables should be arranged to prevent damage to the condenser coils or unit cabinet (see Figure 2).
Figure 1, Suggested Pushing Method
Figure 2, Required Lifting Method
NOTES:
1. All rigging points on a unit, either 4, 6, or 8 locations, must be used. See Figure 7 through Figure 10 for number,
location, and weight at lifting points for a specific size unit. This diagram illustrates a unit with 4 mounting holes
(ALS 141 - ALS 218).
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 condenser sections, and fans can vary from this diagram.
4IOMM ALS-3
Location
Care should be taken in the location of the unit to provide proper airflow to the condenser. (See
Figure 3 through Figure 5 for required clearances).
Due to the vertical condenser coil design of the ALS 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. It is recommended that wind baffles be installed if the unit is
installed with no protection against prevailing winds.
Using less clearances than shown in Figure 3, Figure 4, and Figure 5 will cause discharge air
recirculation to the condenser and could have a significant and detrimental effect on unit performance.
See the current version of McQuay Product Manual PM ALS for more detailed information on the
subject of air recirculation.
Service Access
Each end of the unit must be accessible after installation for periodic service work. Compressors,
filter-driers, and manual liquid line shutoff valves are accessible on each side of the unit adjacent to
the control box. High pressure and low pressure transducers are mounted on the compressor. The
cooler barrel heater thermostat is located on the cooler. Compressor microprocessor and most other
operational and equipment protection controls are located in the unit control box. The solid-state
starters with their internal electrical protection features are mounted on the base side rails adjacent to
the compressor they serve.
On all ALS 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 and fan motor rain shield
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.
Failure to do so may 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 panel with a field mounted disconnect
switch.
IOMM ALS-35
Clearance Requirements
Figure 3, Clearance Requirements, ALS 141-218
Notes:
1. Minimum side clearance between two units is 12 feet.
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 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 8 feet provided no
solid wall above 6 feet is closer than 12 feet to the opposite side of the unit.
5. The evaporator can be removed from the side of the unit.
6. Do not mount electrical conduits, etc, above the side rail on either side if the unit.
7. There must be no obstruction of the fan discharge.
8. It is recommended that field supplied disconnect switches not be mounted on the unit.
6IOMM ALS-3
Figure 4, Clearance Requirements, ALS 245-295
Notes:
1. Minimum side clearance between two units is 12 feet.
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 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 8 feet provided no
solid wall above 6 feet is closer than 12 feet to the opposite side of the unit.
5. The evaporator can be removed from the side of the unit.
6. Do not mount electrical conduits, etc, above the side rail on either side if the unit.
7. There must be no obstruction of the fan discharge.
8. It is recommended that field supplied disconnect switches not be mounted on the unit.
IOMM ALS-37
Figure 5, Clearance Requirements, ALS 325-420
Notes:
1. Minimum side clearance between two units is 12 feet.
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 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 8 feet provided no
solid wall above 6 feet is closer than 12 feet to the opposite side of the unit.
5. The removable post for compressor service access must not be blocked at either side of the unit.
6. Do not mount electrical conduits, etc, above the side rail on either side if the unit.
7. There must be no obstruction of the fan discharge.
8. It is recommended that field supplied disconnect switches not be mounted on the unit.
8IOMM ALS-3
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 are also dimensioned and
the bearing weight at each hole given.
Figure 6, Spring Flex Isolators
Table 1, Spring Vibration Isolators, Part Numbers
Mounting Location (See Footprint Drawings Figure 7 through Figure 10)
ModelR1R2R3R4R5R6R7R8R9R10
ALS 141-ALS 186 Isolator kit part number 350014880
Max Load220022002600260018001800
Spring P/N 02261190102261190102261200002261200022611800022611800
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.
Basically, 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. 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 (e.g., expansion tank or regulating
valve).
5. Water temperature and pressure indicators located at the unit to aid in unit servicing.
6. A strainer or some means of removing foreign matter from the water before it enters the pump.
The strainer should be placed far enough upstream to prevent cavitation at the pump inlet
(consult pump manufacturer for recommendations). The use of a strainer will prolong pump life
and help maintain high system performance levels.
WARNING
7. 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 to the evaporator
connections to prevent any weld slag from entering the vessel.
8. The shell-and-tube evaporator has a thermostat and heating cable to prevent freeze-up down to 20°F (-28.8°C). It is suggested that the heating cable be wired to a separate 110V supply circuit.
As shipped from the factory, it is factory wired to the control circuit. Any 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, the system
should be thoroughly flushed prior to unit installation and then regular chilled water analysis and
chemical water treatment is recommended immediately at equipment start-up.
10. The total water quantity in the system should be sufficient to prevent frequent "on-off" cycling.
For air-conditioning systems, system gallons equal to 7 time the flow rate is recommended.
11. In the event glycol is added to the water system, as an afterthought for freeze protection,
recognize that the refrigerant suction pressure will be lower, cooling performance less, and water
side pressure drop 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.
12. For operations requiring the ice mode feature, logic in MicroTech will adjust the freezestat to a
pressure equivalent to 13.5°F (7.5°C) below the leaving evaporator water temperature. However, if
a different freezestat pressure value is desired, the freezestat can be manually changed through
MicroTech. Refer to the current OM ALSMICRO for additional information.
CAUTION
If a separate disconnect is used for the 110V supply to the cooler heating cable, it should be clearly
marked so that it is not accidentally shut off during cold seasons.
Prior to insulating the piping and filling the system, a preliminary leak check should be made.
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.
12IOMM ALS-3
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 & unloading of
compressors, erratic refrigerant flow in the chiller, improper motor cooling, shortened equipment life
and other undesirable occurrences.
For normal comfort cooling applications where the cooling load changes relatively slowly, we
recommend a minimum system volume of seven minutes times the flow rate (gpm). For example, if the
design chiller flow rate is 400 gpm, we recommend a minimum system volume of 2800 gallons (400 gpm
X 7 minutes).
For process applications where the cooling load can change rapidly, additional system water volume is
needed. A process example would be the cooling of hot metal objects. The load would be very stable
until the hot metal is dipped into the water tank. Then, the load would increase drastically. For this
type of application, we recommend that the normal comfort cooling recommendation addressed above
plus three minutes of ballast for every 10% quick change in load. For example, if the hot metal example
load changes from a stable 50% load to an immediate 100% load for metal cooling, the recommended
system volume would increase to 8800 gallons.
System volume = {400 gpm X 7 minutes} + {(5 increments of 10% increase) X (3 minutes) X 400 gpm}
= 8800 gallons
Since there are many other factors that can influence performance, systems may successfully operate
below these suggestions. However, as the water volume decreases below these suggestions, the
possibility of problems increases.
Variable Water Flow
Variable water flow involves changing the water flow through the evaporator as the load changes.
McQuay chillers are designed for this duty provided 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 change in water flow is listed in the table below. As the number of stages of
control increase, the slower the permissible rate of change in flow rate becomes. The ALS control
logic has timers that limit the rate of unloading or loading allowed. Slow changes allow the chiller the
opportunity to sense a change, react to the change and stabilize preventing operational problems.
ALS Size
141 to 2182810.0
245 to 2953127.5
325 to 4204165.0
For example, assume that an ALS with two compressors has a design flow of 500 gpm and the
minimum vessel flow rate of 300 gpm. The allowable amount of flow change is 200 gpm. An ALS with
two compressors has an allowable change rate of 10% of change per minute. Therefore, the maximum
rate of change recommended would be 20 gpm/minute (200 X .10).
The water flow through the vessel must remain between the minimum and maximum values listed on
Figure 19. 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.
Number of
Compressors
Unloading
Steps
Maximum allowable % per
minute of flow change
IOMM ALS-313
Evaporator Freeze Protection
All evaporators come equipped with thermostatically controlled resistive element heater. When power
is applied to terminals 13 and 16, the heat tape will provide freeze protection down to -20°F (-28.8°C).
However, this should not be the only method of freeze protection. Unless the evaporator is flushed
and drained as is described below in note 4, two or more of the remaining three recommendations must
be followed as part of the system design:
1. Continuous circulation of water through the piping and the heat exchanger.
2. The inclusion of glycol solution in the chilled water circuit.
3. The addition of insulation and heat to the exposed piping.
4. Draining and flushing the chiller vessel with glycol during subfreezing weather.
It is the responsibility of the installing contractor and/or on-site maintenance personnel to insure that
this additional protection is provided. Routine checks should be made to insure adequate freeze
protection is maintained.
Failure to do so may result in damage to unit components. Freeze damage is not considered a
warranty failure.
Figure 11, Typical Field Water Piping
Vent
Outlet
Drain
Vibration
Eliminator
Valved
pressure
gauge
Water
strainer
Vibration
Eliminator
Gate valve
Flow
Balancing
Switch
Protect all field piping
against freezing
valve
Gate valve
Flow Switch
A water flow switch must be mounted in the leaving water line to insure that there will be adequate
water flow to the evaporator before the unit can start. This will safeguard against slugging the
compressors on start-up. It also serves to shut down the unit in the event that water flow is
interrupted to guard against evaporator freeze-up.
A flow switch is available from McQuay under 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 2. Installation
should be as shown in Figure 12.
Electrical connections in the unit control center should be made at terminals 62 and 63. 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 conductors (115 VAC and higher).
Note: Water pressure differential switches are not
recommended for outdoor applications.
MINIMUM REQUIRED FLOW TO
ACTIVATE SWITCH - GPM (LPS)
1 1/4" (32mm) pipe dia.
min. after switch
1 1/4" (32mm) pipe
dia. min. before switch
Water Connections
Water piping to the cooler can be brought up through the bottom of the unit or through the side
between the vertical supports. The dimensional drawings in Figure 20 through Figure 22 give the
necessary dimensions and locations for all piping connections. Evaporator piping connections face
toward the left side of the unit when looking at the control panel.
Refrigerant Charge
All units are designed for use with HCFC-22 (and are compatible with some HCFC alternatives) and are
shipped with a full operating charge. The operating charge for each unit is shown in the Physical Data
Tables. Units ordered with a remote evaporator are shipped with a unit operating charge of refrigerant
pumped down in the unit condensers. The McQuay authorized startup technician will top off the
system charge at startup.
Glycol Solutions
When using glycol anti-freeze solutions the chiller's capacity, glycol solution flow rate, and pressure
drop through the cooler may be calculated using the following formulas and tables.
Note: The procedure below does not specify the type of glycol. Use the derate factors found in Table
3 for corrections when using propylene glycol and those in Table 4 for ethylene glycol.
1. Capacity - Cooling capacity is reduced from that with plain water. To find the reduced value,
multiply the chiller’s water system tonnage by the capacity correction factor to find the chiller’s
capacity when using glycol.
2. Flow - To determine flow (or delta-T) knowing delta-T (or flow) and capacity:
GPM−=
24
factorflowtons
TDelta
3. Pressure drop - To determine pressure drop through the cooler, when using glycol, enter the
water pressure drop curve at the water flow rate. Multiply the water pressure drop found there by
the PD factor to obtain corrected glycol pressure drop.
4. To determine glycol system kW, multiply the water system kW by factor called Power.
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 the supplier normally recommends that a minimum of 25% solution by weight
be used for protection against corrosion.
IOMM ALS-315
CAUTION
Do not use automotive grade antifreeze. Industrial grade glycols must be used. Automotive antifreeze
contains inhibitors that will cause plating on the copper tubes within the chiller evaporator. The type and
handling of glycol used must be consistent with local codes.
The multiple compressor ALS air-cooled chillers are available with the evaporator shipped loose for
remote mounting. This allows the main unit to be installed outdoors to save interior room and
eliminates the need for anti-freeze solutions and heat tracing of chilled water lines since the chilled
water system is indoors. There are some general guidelines to review before proceeding:
1. R-22 only.
2. Maximum line length of 50 ft (15 m) and Total Equivalent Length (TEL) of 120 ft (37 m).
3. Evaporator not more than 6 ft (1.8 m) above the compressor or 16 ft (5 m) below compressor.
6. Units with remote evaporator are not included in the ARI Certification Program.
The remote evaporator is shipped separately, ready for quick and easy installation at the job site. All
refrigerant accessories such as liquid-vapor line shut-off valves, replaceable core filter-driers, liquid
line solenoid valves, electronic expansion valves, and sightglasses are already included on the ALS
condensing unit. The evaporator is equipped with entering and leaving chilled water temperature
sensor wells. The sensors are pre-wired to the ALS unit with 75 feet long sensor leads and must be
field connected to the evaporator thermowells. Suction pressure transducers and temperature sensors
must also be relocated to the evaporator. ALS units are factory charged with a full unit charge
pumped down into the condensers. Field piping must be leak tested, evacuated and charged during
installation. Do not exceed 150 psig test pressure unless the unit is blanked off from the piping.
Performance Derate Factors
All performance tables and adjustment factors found in the current version of the Air-Cooled Screw
Chiller catalog (PM ALS-x) are applicable for remote evaporator installations. However, a performance
derate must be applied to the R-22 performance data due to additional pressure drops in the suction
and liquid lines which cause a loss of compressor performance. These derates are based on a suction
line pressure drop equivalent of approximately 2°F (1°C) change in saturation temperature.
For R-22 applications:
Capacity = Tons (kW) x 0.97Power = Compressor kW x 0.99
16IOMM ALS-3
Refrigerant Piping
General
Careful design of the refrigerant piping is necessary for efficient system operation. The refrigerant
piping should be designed for a low refrigerant pressure drop to obtain maximum capacity and
efficiency while maintaining adequate velocity. Lines should slope in the direction of flow to assure
good oil return to the compressors. Cost considerations favor keeping line sizes as small as possible
while not exceeding acceptable pressure drops in order to maintain unit performance.
NOTE
All refrigerant piping must be reviewed and approved by McQuay Application
Engineers prior to order entry and will be verified by McQuay startup technicians.
Equivalent Line Lengths
Recommended refrigerant line sizes are based on equivalent line lengths of straight pipe, that is, a
combination of straight pipe, fittings and valves. The pressure drop through valves and fittings is
determined by establishing the equivalent straight length of pipe of the same size with the same
friction loss. The "Total Equivalent Length" is the sum of the "Lineal Line Length" and the
appropriate "Valve and Fitting Losses in Equivalent Feet of Pipe for Field Supplied Piping" given in
Table 5
Table 5, Fitting Equivalent Feet of Pipe
Line Size (in.)Angle ValveGlobe Valve90° Std. Radius Elbow90° Long Radius Elbow
Refrigerant lines should be as short and direct as possible to minimize tubing and fittings. Long
radius elbows must be used (except for traps) to minimize the pressure drops. Traps should be as
short as possible to minimize oil accumulation. Refrigerant piping should be arranged so that normal
inspection of the equipment is not hindered. Adequate clearance should be provided between
refrigerant piping and adjacent walls for insulation. Piping should be run so that it does not interfere
with compressor service access, passages or obstruct headroom, windows and doors. Suction line
hangers must be sized and located to support the weight of the piping in accordance with good piping
practice.
Horizontal portions of the suction lines must be downward sloping toward the compressors. Slope all
piping in the direction of flow. Vertical portions of the suction lines must be sized for oil return at
minimum compressor load.
Note: Double section risers must not be utilized on any circuit. Traps must be provided as shown on
Figure 13 and Figure 14.
Suction Line Sizing
Pressure drop in the suction line reduces system capacity and efficiency because it forces the
compressor to operate at lower suction pressure. The suction line should be sized for a pressure drop
approximately equivalent of 2°F (1°C) change in saturation temperature. For suction line sizing see
Table 7 and table 8. For applications with the evaporator below the ALS unit, the vertical section of
the suction lines must be sized to return oil to the compressors at the minimum compressor capacity
step.
IOMM ALS-317
Example of Suction Line Size Calculation
ALS150C condensing unit with refrigerant R-22
Evaporator located 5 feet below the ALS compressor
Lineal length of horizontal suction line is 25 feet
Suction line requires 7 long radius (90°) elbows; 3 in the horizontal, 4 in the riser
From Table 6, the nominal circuit capacities for circuit 1 and 2 are 65 and 80 tons respectively
Total lineal suction line length = 30 feet each circuit (25 feet horizontal plus 5 feet vertical riser).
For the first try, assume that the total equivalent suction line length is twice the lineal suction
line length.
Therefore the estimated total equivalent suction line length = 60 feet
From Table 7 and Table 8, For nominal circuit capacities of 65 & 80 tons and total equivalent line
length of 60 ft, the suction line size = 2 5/8" for horizontal lines and 2 1/8" for vertical lines.
From Table 5, Fitting loss for 2 5/8" long radius (90°) elbow = 4.1 ft, and 3.3 ft for the 2 1/8 elbows.
Therefore fitting loss in equivalent feet of pipe for (3) 2 5/8" long radius (90°) elbow = 12.3 ft, and
13.2 ft for (4) 2 1/8" elbows.
Therefore the actual equivalent suction line length = 30 + 12.3 + 13.2 = 55.5 feet
From and Table 8, For nominal circuit capacities of 65 & 80 tons and equivalent line length of 55.5 ft
the suction line size is correct.
Table 8, Horizontal and Vertical Downflow Suction Line Sizes
Capacity
Tons (kW)
65 (229)75 (23)2 5/8
80 (262)75 (23)2 5/8
95 (334)75 (23)3 1/8
Vertical Downflow and Horizontal Suction LinesNominal Circuit
Equivalent Line Length Ft (m)Suction Line Size, in.
40 (12)2 5/8
115 (35)2 5/8
40 (12)2 5/8
115 (35)3 1/8
40 (12)2 5/8
115 (35)3 1/8
Liquid-Vapor Lines
The liquid-vapor line from the ALS condensing unit to the evaporator liquid connection is not a
conventional liquid line since it carries both liquid and vapor. The compressors on the ALS units
utilize a liquid cooled motor and an economizer. Therefore the expansion valve which feeds the full
flow of liquid refrigerant into the compressor for motor cooling is mounted in the liquid line between
the condenser sub-cooling coil and the compressor inlet, not at the evaporator inlet. The liquid-vapor
line to the evaporator is a low pressure line downstream of the expansion valve and the size is slightly
larger than a normal liquid line. For liquid line sizing see Table 9 and Table 10.
Table 10, Horizontal and Vertical Downflow Liquid-Vapor Line Sizes
Capacity
Tons (kW)
65 (229)75 (23)1 3/8
80 (262)75 (23)1 5/8
95 (334)75 (23)1 5/8
Vertical Downflow and Horizontal Liquid-Vapor LinesNominal Circuit
Equivalent Line Length
Ft (m)
40 (12)1 3/8
115 (35)1 3/8
40 (12)1 3/8
115 (35)1 5/8
40 (12)1 5/8
115 (35)1 5/8
Liquid-Vapor Line Size
o.d (in.)
Figure 13, Evaporator Above ALS Unit
Evaporator
Trap
ALS Unit
Suction Line
IOMM ALS-319
Figure 14, Evaporator Below ALS Unit
ALS Unit
Suction Line
Evaporator
Trap
NOTE: Keep the trap width at a minimum to avoid trapping excessive oil.
Insulation
All piping joints and fittings must be thoroughly leak tested before insulation is applied. Suction lines
must be insulated and should not be installed underground. Suction line insulation must be selected
to prevent condensation under local ambient conditions with the lines at 40°F to 50°F (4.4°C to 10°C)
operating temperatures. The liquid-vapor lines will operate at 40°F to 60°F (4.4°C to 15.6°C) and must
also be insulated to prevent sweating and heat gain.
20IOMM ALS-3
Startup Procedures
NOTE: McQuayService or a factory authorized McQuay service agent must do initial start-up and
commissioning.
Filter Driers
Following an initial 24 hour operation the pressure drop across the replaceable core filter-drier should
be checked. If this pressure drop exceeds the values given in Table 11 at the various load conditions
the filter drier cores must be replaced. Also if the moisture indicating sight glass shows a wet system
condition after 24 hours of operation the filter cores must be changed. This should remove any
contaminants introduced during field piping. The filter drier cores must also be changed anytime the
system is opened for servicing.
Table 11, Filter Drier Pressure Drop
Percent Circuit
Loading (%)
1007 (48.3)
755 (34.5)
503 (20.7)
253 (20.7)
Refrigerant and Oil Charge
The relative position of the ALS unit and the evaporator and the distance between them plays a
critical role in determining suction and liquid line sizes and the field refrigerant and oil charges. ALS
units with the remote evaporator option are shipped with a unit operating charge of refrigerant and oil.
It will be necessary to evacuate the evaporator and field installed line and top off the charge See
Table 12 for refrigerant charge for suction and liquid-vapor lines. McQuay Service will supply and
add additional oil as required. The correct oil is Planetelf ACD68AW, McQuay Part No. 735030439 (5
gal.), 735030438 (1 gal.).
Maximum Recommended Pressure Drop Across Filter Drier
psig (kPa)
Charging Procedure
The calculated refrigerant charge must be added through the factory supplied charging valve located
on the liquid-vapor line coming out of the compressor. Sufficient charge must be added to clear the
liquid line sight glass located at the outlet of the condenser. Add an extra 10 lb. of refrigerant after the
sight glass is clear.
Table 12, Refrigerant Charge for Suction and Liquid-Vapor Lines
Lineal Tubing
Length
ft (m)
10 (3)2 5/80.51 (0.23)1 5/85.0 (2.3)
20 (6)2 5/81.02 (0.46)1 5/810.0 (4.5)
30 (9)2 5/81.53 (0.69)1 5/815.0 (6.8)
40 (12)2 5/82.04 (0.92)1 5/820.0 (9.0)
Suction Line Refrigerant Charge
lb (kg)
Line (in.)R-22Line (in.)R-22
2 1/80.33 (0.15)1 3/83.6 (1.6)
3 1/80.71 (0.32)
2 1/80.66 (0.30)1 3/87.2 (3.3)
3 1/81.42 (0.64)
2 1/80.99 (0.45)1 3/810.8 (4.9)
3 1/82.13 (0.96)
2 1/81.32 (0.60)1 3/814.4 (6.5)
3 1/82.84 (1.29)
Notes:
1. The only approved oil is that identified on the label attached to the compressors. All POE oils are
hygroscopic and care should be exercised in handling the oil to avoid absorption and retention of
moisture.
2. Do not leave the oil container open for more than a minute while charging oil. Do not use oil that
has not been properly sealed and stored.
3. Charge must never be added through the compressor suction line
Liquid-Vapor Line Refrigerant Charge
lb (kg)
IOMM ALS-321
Dimensions
Use the ALS dimension drawings Figure 20 through Figure 22 for the ALS with remote evaporator.
The refrigerant connections are located approximately where the refrigerant connections to the unit
mounted evaporator are on a packaged chiller. The remote evaporator dimensions are Figure 15
through Figure 18.
The chilled water flow through the evaporator should be adjusted to meet specified conditions. The
flow rates must fall between the minimum and maximum values shown in. Flow rates below the
minimum values shown will result in laminar flow that will reduce efficiency, cause erratic operation of
the electronic expansion valve and could cause low temperature cutouts. On the other hand flow rates
exceeding the maximum values shown can cause erosion on the evaporator water connections and
tubes.
Measure the chilled water pressure drop through the evaporator at field installed pressure taps. It is
important not to include valve or strainer pressure drop in these readings.