McQuay ACZ 010A User manual

Installation, Operation and Maintenance Manual IOMM ACZ1
Group: Chiller
Part Number: 330262002
Effective: December 2001
Supersedes: New
Air-Cooled Scroll Condensing Units
ACZ 010A – ACZ 039A
10 to 43 Tons, 35 to 150 kW
R-22, 60 Hertz

2ACZ 010A through 039A IOMM ACZ1
Table of Contents
Introduction........................................3
General Description..........................................3
Inspection.........................................................3
Installation........................................................3
Handling...........................................................3
Location ...........................................................4
Service Access..................................................4
Vibration Isolators............................................6
Chilled Water System.......................................6
Refrigerant Piping............................................9
Unit Component Location..............................12
Control Layout and Operation.......13
Control Center................................................13
Start-up and Shutdown...................13
Pre Start-up ....................................................13
Start-up...........................................................13
Sequence of Operation...................................14
Physical Data....................................15
Electrical Data..................................17
Field Wiring ...................................................17
Dimensional Data.............................22
System Maintenance........................23
General...........................................................23
Lubrication.....................................................23
Electrical Terminals........................................23
Condensers.....................................................23
Refrigerant Sightglass ....................................23
Standard MicroTech II Controller.24
Table of Contents ...........................................24
Overview........................................................25
General Description .......................................25
Using the Controller.......................................31
Service...............................................42
Thermostatic Expansion Valve.......................42
Filter-Driers....................................................42
Liquid Line Solenoid......................................42
Optional Controls...........................................43
Troubleshooting Chart....................................45
MODEL CODE
A C Z XXX A
"McQuay" is a registered trademark of McQuay International
2001 McQuay International
"Illustrations and data cover 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"
Air-Cooled
Condensing
Scroll Compressor
Vinta
g
e
N
ominal Tons

IOMM ACZ1 ACZ 010A through 039A 3
Introduction
General Description
McQuay air-cooled condensing units are complete, self-contained automatic refrigerating units.
Every unit is completely assembled, factory wired, and tested. Each unit consists of air-cooled
condensers, Copeland Compliant Scrollhermetic compressor, and internal refrigerant piping, ready
to be piped to a field supplied low side.
The electrical control center includes all equipment protection and operating controls necessary for
automatic operation except for the staging control for the steps of capacity in the unit. Condenser fan
motors are three-phase (except single-phase on No. 1 fan with SpeedTrol option) and started by their
own contactors with inherent overload protection. The compressor has solid-state motor protection
for inherent thermal overload protection except Models ACZ 010 and 013 that have internal line
breakage.
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 nameplate before unloading to be
sure it agrees with the power supply available. Units are shipped FOB factory and McQuay is not
responsible for physical damage after the unit leaves the factory.
Note: Unit shipping and operating weights are listed on pages 15 and 16.
Installation
Note: Installation is to be performed by qualified personnel who are familiar with local codes
and regulations, especially concerning refrigerant release to the atmosphere.
WARNING
Sharp edges and coil surfaces can cause personal injury. Wear protective gear and 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, lifting slots 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).

4ACZ 010A through 039A IOMM ACZ1
Figure 1, Suggested Pushing Arrangement
Figure 2, Suggested Lifting Arrangement
Location
Unit Placement
ACZ units are for outdoor applications and can be mounted on a roof or at 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 on pages 15 and
16.
Since its operation is affected by wind, the unit should be located so that its length is parallel with the
prevailing wind. If this is not practical, field fabricated wind deflectors may be required.
Service Access
Each end of the unit must be accessible after installation for periodic service. Compressors, filter-
driers, and liquid line solenoid valve are accessible from the end of the unit. Motor protector controls
are on the compressor. Most operational, equipment protection, and starting controls are located in
the unit control box.
The fan deck with the condenser fans and motors can be removed from the top of the unit.
Blocking required
across full width

IOMM ACZ1 ACZ 010A through 039A 5
Clearances
The flow of air to and from the condenser
coil must not be limited. Restricting
airflow 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
compressors, electrical control panel and
piping components as shown in Figure 3.
Do not block access to the unit with piping
or conduit.
Do not allow debris to accumulate near the
unit. Air movement can 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 low sound levels of the ACZ units are
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
electrical conduit and the unit itself. Use
wall sleeves and rubber isolated refrigerant
piping hangers to reduce transmission of
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 the compressors and for
unit isolation in sound-sensitive areas.
Figure 3, Clearance requirements
4 Ft.
(1220mm)
Clearance for
Service Access
4 Ft. (1220mm)
Clearance for Air Inlet
4 Ft.
(1220mm)
Clearance for
Service Access
4 Ft. (1220mm)
Clearance for Air Inlet
The recommended minimum side clearance between two units
is 8 feet (2440mm).
The unit must not be installed in a pit or enclosure that is
deeper or taller than the height of the unit unless extra space
is provided. The minimum clearance on each side of the
unit is 6 feet (1828mm) when installed in a pit. The pit cannot
be deeper than the unit.
The minimum clearance to a side wall or building taller than
the unit height is 6 feet (1828mm) provided no solid wall
above 6 feet (1828mm) tall is closer than 12 feet (3658mm)
to the opposite side of the unit.

6ACZ 010A through 039A IOMM ACZ1
Vibration Isolators
Vibration isolators are recommended for all roof-mounted installations or wherever vibration
transmission is a consideration. The isolators can be purchased from McQuay by the part numbers
shown in the table.
The unit should be initially on shims or blocks at the listed free height. When all piping, wiring,
flushing, charging, etc. is completed, the springs are adjusted upward to loosen the blocks or shims
that are then removed.
A rubber anti-skid pad is part of the isolator. Installation of spring isolators requires flexible piping
connections and at least three feet of flexible conduit to avoid straining the piping and transmitting
vibration and noise.
Table 1, Recommended Vibration Isolators
ACZ UNIT ISOLATOR
TYPE ISOLATOR PART NO. NUMBER REQUIRED KIT of FOUR PART NO. LOCATION ISOLATOR
DESCRIPTION
021639703 2 LF, RF RP-3 Green
010A – 039A Rubber-in-Shear 021639701 2 350014857 LB, RB RP-3 Red
010A – 020A Spring Isolators 047792726 4 350014835 All CP-1-26
047792726 2 LF, RF CP-1-27
025A – 039A Spring Isolators 047792727 2 350014839 LB, RB CP-1-26
Note: See dimension drawing for location of isolators
Corner Operating Weights
ACZ
Unit
Model RF LF RB LB Total
010 309 311 190 190 1000
013 309 311 190 190 1000
016 402 404 207 207 1220
020 511 513 158 158 1340
025 492 494 242 242 1470
028 498 501 245 246 1490
033 614 567 302 277 1760
039 683 630 336 311 1960
Chilled Water System
Water Piping (Applicable when the Unit is Field Connected to a Water
Type Evaporator)
Local authorities can supply the installer with the proper building and safety codes required for 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.
RBI
LBI
RFI
LFI
Control
Panel

IOMM ACZ1 ACZ 010A through 039A 7
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. Pressure gauge
taps must be installed in the chilled water inlet and outlet piping or as shown in Figure 4.
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 help prolong pump life and keep
system performance up.
7. A 40-mesh strainer is required 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.
8. 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
on the evaporator is recommended immediately at equipment start-up.
9. 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 38°F (3.3°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.
10. Perform a preliminary leak check before insulating the piping and filling the system.
11. Piping insulation should include a vapor barrier to prevent condensation and possible damage to
the building structure.
Figure 4, Typical Field Evaporator Water Piping
Air
Vent
Flow
Switch
Vibration
Eliminators
Drain
Outlet
Inlet
PIsolation
Valves
Strainer
System 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 occurrences.

8ACZ 010A through 039A IOMM ACZ1
For normal comfort cooling applications, where the cooling load changes relatively slowly, we
recommend a minimum system volume of five minutes times the flow rate (gpm). For example, if the
design chiller flow rate is 50 gpm, we recommend a minimum system volume of 250 gallons (50 gpm
x 5 minutes).
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 Chilled Water flow
Variable chilled water flow systems are not recommended for this class of equipment due to limited
unloading capability.
Flow Switch
Mount a water flow switch in the leaving
water line to shut down the unit when water
flow is interrupted.
A flow switch is available from McQuay
(part number 017503300). It is a “paddle”
type switch and adaptable to pipe sizes
down to 1 1/4” (32mm) nominal. Certain
minimum flow rates are required to close
the switch and are listed in Table 2. Install
the switch as shown in Figure 5. Connect
the normally open contacts of the flow
switch in the unit control center at terminals
4 and 5. 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. Follow installation instructions provided with the flow switch. Calibrate the flow
switch to open at one-half of nominal flow rate.
Caution: Differential pressure switches are not recommended for outdoor installation. They
are subject to freezing-up at low ambient temperatures.
Table 2, Flow Switch Settings
inch 1 1/4 1 1/2 2 2 1/2 3 4
Pipe Size mm 32 38 51 63 76 102
gpm 4.8 6.3 9.9 15.3 24.4 33.3
Flow Lpm 18.2 22.7 37.5 57.9 92.4 126.0
gpm 3.0 3.6 5.9 9.5 15.4 21.1
Minimum
Adjustment No
Flow Lpm 11.3 13.6 22.3 36.0 58.3 79.9
gpm 7.7 10.0 15.8 23.7 35.5 61.4
Flow Lpm 29.1 37.9 59.8 89.7 134.4 232.4
gpm 5.9 7.0 11.0 17.0 29.2 37.7
Maximum
Adjustment No
Flow Lpm 22.3 26.5 41.6 64.3 110.5 142.7
Figure 5, Flow Switch Installation

IOMM ACZ1 ACZ 010A through 039A 9
Refrigerant Piping
Introduction
Proper refrigerant piping can represent the difference between a reliable, trouble free system and
months or years of inefficient, problematic performance.
System concerns related to piping are:
1. Refrigerant pressure drop
2. Solid liquid feed to the expansion valve(s)
3. Continuous oil return
The most important and least understood is number 3. “Continuous oil return”. The failure of oil to
return at or close to the rate of displacement from the compressor can result in oil trapping and
ultimate compressor failure.
On the other hand, the instantaneous return of a large volume of compressor oil (slug) can be equally
damaging to a compressor.
All compressors displace some oil during operation. Oil is carried into the compressor with suction
gas; and that same gas entrains oil present on the compressor walls as it is being compressed. The
sum of the two is then pumped into the discharge piping.
More oil is displaced at compressor start-up than during the normal running periods. If a compressor
experiences excessive starts because of recycling pumpdown control, the oil can be pumped out and
trapped in the condenser with the refrigerant charge. This oil can not return regardless of the
adequacy of the piping system.
A similar problem to a lesser extent occurs when the equipment is oversized for the available cooling
load.
In short, extreme care should be exercised to assure that both piping and controls are suitable for the
application such that displaced oil is returned to the compressor moderately. Note that oil loss to the
system can be due to a hang up in the evaporator, as well as in the piping.
Suction Lines
McQuay recommends the use of ASHRAE for guidelines in sizing and routing piping with one
exception. See the 1998 ASHRAE Handbook Refrigeration Edition, Chapter 2 for tables and
guidelines. The single exception is to the piping of direct expansion cooling coils located above the
compressors. In all cases, regardless of whether the equipment has pumpdown control or not, a trap
in the suction line equal to the height of the coil section is recommended. In its absence, upon a
power failure, all of the liquid in the coil will fall by gravity to the compressor below.
Suction line gas velocities can range between 900 and 4000 feet per minute. Consideration should be
given to the possibility of objectionable noise in or adjacent to occupied space. Where this is a
concern, gas velocities on the low side are recommended.
Routing must also take into account the requirement established in the latest ANSI/ASHRAE 15.
To size the suction line, determine:
a. The maximum tons for the circuit
b. The actual length in feet
c. The equivalent length contributed by elbows, fittings, valves or other refrigerant specialties.
ASHRAE Tables 2-10, 11 & 12
d. If a vertical riser exists including the trap at the coil, determine the minimum tons for the
circuit.

10 ACZ 010A through 039A IOMM ACZ1
Add b and c above to obtain the total equivalent feet. Use the ASHRAE table for R22. Suction line
selections are based upon the pressure equivalent of a 2ºF loss per 100 equivalent feet.
Select a line size that displays an equal or slightly larger tons then that determined in a) above.
To determine the actual line loss:
1. Modify the table tons by the value for the design condensing temperature.
2. Use the formula in the notes to calculate the line loss in terms of the saturation temperature.
3. Convert the saturation temperature loss calculated to a pressure drop equivalent using the (Delta)
listed in the table for the comparable delta temperature.
Caution: Excessive pressure drop is undesirable because:
•It reduces available compressor capacity.
•It increases power consumed for the net tons realized.
•It can affect the performance of both the evaporator and the expansion valve previously selected
for the application.
The line loss calculated, expressed in temperature, or PSID pressure drop will be used to establish the
temperature required at the evaporator to produce the required cooling, as well as, the suction
pressure that the compressor must operate at to deliver the required capacity.
Having selected the suction line size, based upon total equivalent length and maximum tons, verify
the line size selected will maintain entrainment of the lubricating oil up any vertical risers at the
minimum tons for the circuit. See d) above, and ASHRAE Tables.
If the line size selected will not maintain satisfactory oil return in a suction riser, the following options
are available:
The vertical length can be sized smaller to accommodate the lower circuit tons at reduced load.
Hot gas bypass can be introduced at the distributor to the evaporator, increasing the volume of gas
available in the suction line to entrain the oil.
An oil separator can be installed in the discharge line.
Note: In horizontal refrigerant gas lines, oil return to compressors is provided by sizing lines at a
velocity above the minimum recommended and pitching the lines in the direction of refrigerant flow.
Underground Refrigerant Lines
McQuay does not recommend the installation of suction lines underground. If job conditions require
that they be located below ground, a suitable sized suction accumulator must be installed ahead of the
compressor to interrupt liquid refrigerant slugs at start-up.
Long Vertical Riser Installation
Where job conditions require refrigerant gas lifts of more than 25 feet, McQuay recommends the
installation of a short trap half-way up the riser or at not more than 20 feet intervals. These traps are
required to capture and hold small quantities of oil during off cycles.

IOMM ACZ1 ACZ 010A through 039A 11
Figure 6, DX Coil Piping
Condensing Unit Above Coil Condensing Unit Below Coil
EXPANSION VALV
E
CONTROL BULB
STRAP TO LINE
AND INSULATE
SUCTION TRAP
SHORT AS
FITTINGS PERMIT
LIQUID TO
COIL
SUCTION
PITCHTO
COMPRESSOR
Liquid Lines
Liquid lines are generally sized for 1 to 2 degree F line losses or their equivalent in pressure drop.
Actual selection can vary based upon the pressure drop expected from refrigerant specialties such as
solenoids, refrigerant driers, valves, etc. piping lifts or risers and the amount of condenser sub-cooling
expected.
The principal concern in sizing and routing liquid lines is assurance that liquid is present in the line at
start-up of the compressor, and that liquid and not vapor is available at the inlet to the expansion
valve during system operation.
Liquid can not be available in a liquid line at start-up if:
1. The solenoid valve is located adjacent to the condenser or condensing unit, remote from the
expansion valve.
2. An excessive length of liquid line is located in a heated ambient and the application permits
migration of the refrigerant to a cold air-cooled condenser.
3. Liquid refrigerant is permitted to gravitate from the liquid line to the condenser because of the
relative location of components.
In the event 2) or 3) above are possible, the application should include a check valve at the condenser
end of the liquid line. The check valve should be a low-pressure drop valve. The line between the
check valve and the solenoid valve can be comparable to a pressure vessel and as the line becomes
heated refrigerant trapped in the confined space will increase in pressure. The check valve should
include a pressure relief devise, relieving from the line side to the condenser side of the circuit. The
relief can be sized for a pressure differential from 80 to 180 psi, but not more than 180 psi, and
should be auto-resetting as the pressure is relieved.
Liquid line solenoid valves should be located adjacent to the expansion valve with possibly only a
sight glass interposing the two.
If liquid lines are short, they may be of smaller diameter than the size indicated in the current
ASHRAE Refrigerant Handbook. As indicated above, the designer must size the liquid line to assure
that pure liquid will reach the inlet of the expansion valve. If the condenser is sized to produce 10ºF
of subcooling, and each degree represents 3.05 psi with R-22, the liquid line and its refrigerant
specialties can have pressure losses totaling 10 x 3.05 psi (or 10 x 2.2) and still satisfy the objective
of delivering pure liquid to the expansion valve.

12 ACZ 010A through 039A IOMM ACZ1
In calculating the pressure losses, or gains, note that each foot of rise in a liquid line results in an
approximate 0.5 psi loss. Thus a 10 foot rise represent 5 pounds per square inch loss in refrigerant
pressure, or the equivalent of 1.6ºF subcooling with R-22. Total line losses will include values for
line friction, equivalents for valves and elbows and pressure losses from manufacturers’ catalogs for
driers, solenoids, sight glasses, etc.
When calculating condenser subcooling, note that saturated condensing pressure should be read at the
same point in the system where the liquid refrigerant temperature is obtained.
Unit Component Location
Control Panel
Tandem Scroll
Compressors
Solenoid Valve, Expansion Valve
Optional Hot Gas Bypass ValveFilter Drier
Evaporator Charging Valve

IOMM ACZ1 ACZ 010A through 039A 13
Control Layout and Operation
Control Center
All electrical controls are enclosed in a weather resistant control center with tool-locked, hinged
access doors. The left-hand section contains the microprocessor controller and control input and
output terminals. All high-voltage components are located on the right side of the panel.
Start-up and Shutdown
Pre Start-up
1. The chilled-water system should be flushed and cleaned or air filters checked for cleanliness on
DX systems.
2. Open all electric disconnects and check all electric connections for tightness.
3. Inspect all water piping for flow direction and correct connections at the evaporator or ductwork
for tightness and completeness.
4. Verify that thermostat connections for two stages of control have been connected to unit terminals
23 / J5-ID7 and 28 / J5- ID-8.
5. Check compressor oil level. The oil level should be visible in the oil sightglass.
6. Check voltage of the unit power supply and make certain voltage is within ±10% of nameplate
rating. Check unit power supply wiring for proper ampacity and a minimum insulation
temperature of 75°C. Check for proper phasing using a phase sequence meter.
7. Verify all mechanical and electrical inspections have been completed according to local codes.
8. Open control stop switch S1(off). Turn on the main power and control disconnect switches. This
will energize crankcase heaters. Wait at least 24 hours before starting up unit.
Start-up
1. Start auxiliary equipment by turning on the following: time clock (if present), ambient thermostat
and/or remote on/off switch, chilled water pump or air handler.
2. If the field supplied staging control calls for cooling, the unit will begin the start-up sequence.
3. After running the unit for a short time, check the oil level in the compressor (1/4 to 1/3 of the
glass), rotation of fans, and flashing in refrigerant sightglass.
4. Verify superheat temperature is at the factory setting of 8 to 12 degrees F (4.4 to 6.7 degrees C).
5. After system performance has stabilized, complete the current ACZ Start-Up Form (obtainable
from the local McQuay sales office) to establish inception of warranty benefits. Return the form
to McQuay International through your sales representative.
MicroTech II
SpeedTrol Location
Field Connection
Terminals
Control
Transformer 24-Volt Trans.
Non-Fused Disc.
or
Power Block
Fan
Contactors
Fan
Protection
Compressor Contactors
ON/OFF Switch

14 ACZ 010A through 039A IOMM ACZ1
Sequence of Operation
The following sequence of operation is typical for Models ACZ 010A through ACZ 039A. It can
vary depending upon options.
Start-Up
With the control circuit power on, 115V power is applied through the control circuit fuse F1 to the
compressor crankcase heaters, the compressor motor protections and the primary of the 24V control
circuit transformer. The 24V transformer provides power to the microprocessor controller.
If an optional remote time clock or remote manual switch is field wired to the unit (terminals 25 and
35), it must be closed in order to start the unit. The operation of the unit is then under the control of
the field supplied staging thermostat. The two compressors will start when the normally open staging
contacts close.
Equipment Protection Alarms
The following conditions will shut down the unit and activate the alarm circuit:
•No water or air flow •Low evaporator pressure
•High condenser pressure •Motor protection system
•Phase voltage protection (Optional) •Outside ambient temperature
•Sensor failures
The following alarms will limit unit operation:
•Condenser pressure stage down, unloads unit at high discharge pressures
•Low ambient lockout, shuts off unit at low ambient temperatures
•Low evaporator pressure hold, holds stage #1 until pressure rises
•Low evaporator pressure unload, shuts off stage #2
Unit Enable Selection
Enables unit operation from local keypad, digital input, or Building Automation System.
Unit Mode Selection
Selects standard cooling or test operation mode. (Test is for service personnel only.)
Condenser Fan Control
Control of condenser fans is provided by the MicroTech II controller. The control steps condenser
fans based on discharge pressure.
Shutdown
As the Stage #2 external staging thermostat is satisfied, it will stage off the lag compressor unloading
the unit. The Stage #1 will de-energize the liquid line solenoid valve SV1 and the lead compressor
will pump down the unit and shut off on Low Suction Pressure at 40 psig. If the low pressure cutoff
point cannot be reached in 120 seconds, the compressor will time off. The compressor crankcase
heaters will energize when the compressors shut off, keeping the small amount of refrigerant in the
plate heat exchanger from migrating to the compressor. See page 29 for detailed explanation of
compressor staging.

IOMM ACZ1 ACZ 010A through 039A 15
Physical Data
Table 3, Physical Data, ACZ 010A through 020A
ACZ MODEL NUMBER
PHYSICAL DATA 010A 013A 016A 020A
BASIC DATA
Number Of Refrigerant Circuits 1 1 1 1
Unit Operating Charge, R-22, Lb. (kg), Note 1 22.0 (10.0) 22.0 (10.0) 24.0 (10.9) 31.0 (14.1)
Cabinet Dimensions, LxWxH, In. 73.6 x 46.3 x 50.8 73.6 x 46.3 x 50.8 73.6 x 46.3 x 50.8 73.6 x 46.3 x 50.8
Cabinet Dimensions, LxWxH, (mm) (1869) x (1176) x
(1289) (1869) x (1176) x (1289) (1869) x (1176) x (1289) (1869) x (1176) x (1289)
Unit Operating Weight, Lbs. (kg) 1000 (454) 1000 (454) 1220 (554) 1340 (608)
Unit Shipping Weight, Lbs. (kg) 1080 (490) 1080 (490) 1300 (590) 1420 (645)
Add'l Weight If Copper Finned Coils, Lb. (kg) 220 (99.7) 220 (99.7) 220 (99.7) 220 (99.7)
COMPRESSORS
Type Scroll Scroll Scroll Scroll
Nominal Horsepower 4.0 / 4.0 6.0 / 6.0 7.5 / 7.5 9.0 / 9.0
Oil Charge Per Compressor, Oz. (g) 57 (1616) 60 (1701) 140 (3969) 140 (3969)
CAPACITY REDUCTION STEPS - PERCENT OF COMPRESSOR DISPLACEMENT
Standard Staging 0 – 50 – 100 0 – 50 – 100 0 – 50 – 100 0 – 50 – 100
CONDENSERS - HIGH EFFICIENCY FIN AND TUBE TYPE WITH INTEGRAL SUBCOOLING
Coil Face Area,Sq. Ft. (M2) 30.3 (2.8) 30.3 (2.8) 30.3 (2.8) 30.3 (2.8)
Finned Height x Finned Length, In. 84 x 52 84 x 52 84 x 52 84 x 52
Finned Height x Finned Length, (mm) (2134) x (1321) (2134) x (1321) (2134) x (1321) (2134) x (1321)
Fins Per Inch x Rows Deep 16 x 2 16 x 2 16 x 2 16 x 3
Pumpdown Capacity lb. (kg) 35.3 (16.0) 35.3 (16.0) 35.3 (16.0) 50.3 (22.8)
CONDENSER FANS - DIRECT DRIVE PROPELLER TYPE
Number Of Fans - Fan Diameter, In. (mm) 2 – 26 (660) 2 – 26 (660) 2 – 26 (660) 2 – 26 (660)
Number Of Motors - HP (kW) 2 – 1.0 (0.75) 2 – 1.0 (0.75) 2 – 1.0 (0.75) 2 – 1.0 (0.75)
Fan And Motor RPM, 60 Hz 1140 1140 1140 1140
Total Unit Airflow, CFM (l/s), 60 Hz 13950 (6584) 13950 (6584) 13950 (6584) 12000 (5664)
Note 1: Operating charge is for the condensing unit only. Refrigerant lines and evaporator charge must be added.

16 ACZ 010A through 039A IOMM ACZ1
Table 4, Physical Data, ACZ 025A through 039A
ACZ MODEL NUMBER
PHYSICAL DATA 025A 028A 033A 039A
BASIC DATA
Number Of Refrigerant Circuits 1 1 1 1
Unit Operating Charge, R-22, Lb. (kg), Note 1 34.0 (15.4) 36.0 (16.3) 47.0 (21.3) 50.0 (22.7)
Cabinet Dimensions, LxWxH, In. 106.2x 46.3 x 50.8 106.2x 46.3 x 50.8 106.2x 46.3 x 58.8 106.2x 46.3 x 58.8
Cabinet Dimensions, LxWxH, (mm) (2697) x (1176) x
(1289) (2697) x (1176) x (1289) (2697) x (1176) x (1493) (2697) x (1176) x (1493)
Unit Operating Weight, Lbs. (kg) 1470 (667) 1490 (676) 1760 (799) 1960 (890)
Unit Shipping Weight, Lbs. (kg) 1580 (717) 1600 (726) 1890 (858) 2090 (949)
Add'l Weight If Copper Finned Coils, Lb. (kg) 350 (159) 350 (159) 435 (197) 435 (197)
COMPRESSORS
Type Scroll Scroll Scroll Scroll
Nominal Horsepower 10.0 / 13.0 13.0 / 13.0 15.0 / 15.0 20.0 / 20.0
Oil Charge Per Compressor, Oz. (g) 140 (3969) 140 (3969) 140 (3969) 296 (8392)
CAPACITY REDUCTION STEPS - PERCENT OF COMPRESSOR DISPLACEMENT
Standard Staging 0 – 45 - 100 0 – 50 – 100 0 – 50 – 100 0 – 50 – 100
CONDENSERS - HIGH EFFICIENCY FIN AND TUBE TYPE WITH INTEGRAL SUBCOOLING
Coil Face Area,Sq. Ft. (M2) 49.0 (4.6) 49.0 (4.6) 58.3 (5.4) 58.3 (5.4)
Finned Height x Finned Length, In. 84 x 84 84 x 84 100 x 84 100 x 84
Finned Height x Finned Length, (mm) (2134) x (2134) (2134) x (2134) (2545 ) x (2134) (2545 ) x (2134)
Fins Per Inch x Rows Deep 16 x 2 16 x 2 16 x 3 16 x 3
Pumpdown Capacity lb. (kg) 53.1 (24.0) 53.1 (24.0) 90.7 (41.1) 92.8 (42.0)
CONDENSER FANS - DIRECT DRIVE PROPELLER TYPE
Number Of Fans - Fan Diameter, In. (mm) 3 – 26 (660) 3 – 26 (660) 3 – 26 (660) 3 – 26 (660)
Number Of Motors - HP (kW) 3 – 1.0 (0.75) 3 – 1.0 (0.75) 3 – 1.0 (0.75) 3 – 1.0 (0.75)
Fan And Motor RPM, 60 Hz 1140 1140 1140 1140
Total Unit Airflow, CFM (l/s), 60 Hz 20925 (9877) 20925 (9877) 19800 (9346) 19800 (9346)
Note 1: Operating charge is for the condensing unit only. Refrigerant lines and evaporator charge must be added.

IOMM ACZ1 ACZ 010A through 039A 17
Electrical Data
Field Wiring
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.
ACZ 010A through ACZ 039A units have single-point power connection. A single field supplied fused
disconnect is required or it can be supplied as a factory-mounted option. The control transformer is factory
mounted.
Table 5, ACZ 010A – 039A, Electrical Data Single Point
Power Supply
Field Wire Hub (Conduit Connection)
Field Fuse Size
or HACR (Heating/Air-
Conditioning/Refrigeration)
Breaker Size
ACZ
Unit
Size Volts Hz.
Minimum
Circuit
Ampacity
(MCA) Quantity Wire
Gauge Quantity Nominal
Size
In. (mm) Recommended Maximum
208 42 3 8 1 1.00 (25) 50 50
230 42 3 8 1 1.00 (25) 50 50
460 22 3 10 1 1.00 (25) 25 25
010A
575
60
18 3 10 1 1.00 (25) 20 20
208 54 3 6 1 1.00 (25) 60 70
230 54 3 6 1 1.00 (25) 60 70
460 26 3 10 1 1.00 (25) 30 30
013A
575
60
23 3 10 1 1.00 (25) 30 30
208 65 3 6 1 1.00 (25) 80 80
230 65 3 6 1 1.00 (25) 80 80
460 34 3 10 1 1.00 (25) 40 45
016A
575
60
27 3 10 1 1.00 (25) 30 35
208 79 3 4 1 1.00 (25) 90 100
230 79 3 4 1 1.00 (25) 90 100
460 41 3 8 1 1.00 (25) 45 50
020A
575
60
33 3 10 1 1.00 (25) 40 40
208 103 3 2 1 1.25 (32) 125 125
230 103 3 2 1 1.25 (32) 125 125
460 53 3 6 1 1.00 (25) 60 70
025A
575
60
45 3 8 1 1.00 (25) 50 60
208 110 3 2 1 1.25 (32) 125 150
230 110 3 2 1 1.25 (32) 125 150
460 58 3 6 1 1.00 (25) 70 70
028A
575
60
48 3 8 1 1.00 (25) 60 60
208 136 3 1/0 1 1.50 (38) 150 175
230 136 3 1/0 1 1.50 (38) 150 175
460 62 3 6 1 1.00 (25) 70 80
033A
575
60
58 3 6 1 1.00 (25) 70 70
208 175 3 2/0 1 1.50 (38) 200 225
230 175 3 2/0 1 1.50 (38) 200 225
460 88 3 3 1 1.25 (32) 100 110
039A
575
60
72 3 4 1 1.00 (25) 90 100
See page 20 for all Electrical Data notes.

18 ACZ 010A through 039A IOMM ACZ1
Table 6, ACZ 010A – 039A Compressor and Condenser Fan Motor Amp Draw
Rated Load Amps Locked Rotor Amps
Compressors Compressors
Across-The-Line
ACZ
Unit
Size Volts Hz. No. 1 No. 2
Fan
Motor
(Each)
No. of
Fan
Mtrs Fan
Motor
(Each) No. 1 No. 2
208 13.5 13.5 5.8 2 23.7 115 115
230 13.5 13.5 5.8 2 21.4 115 115
460 7.0 7.0 2.8 2 10.7 47.5 47.5
010A
575
60
5.0 5.0 3.0 2 11.5 37.5 37.5
208 18.6 18.6 5.8 2 23.7 156 156
230 18.6 18.6 5.8 2 21.4 156 156
460 9.0 9.0 2.8 2 10.7 75 75
013A
575
60
7.4 7.4 3.0 2 11.5 54 54
208 23.7 23.7 5.8 2 23.7 189 189
230 23.7 23.7 5.8 2 21.4 189 189
460 12.5 12.5 2.8 2 10.7 99 99
016A
575
60
9.1 9.1 3.0 2 11.5 74 74
208 29.9 29.9 5.8 2 23.7 232 232
230 29.9 29.9 5.8 2 21.4 232 232
460 15.3 15.3 2.8 2 10.7 125 125
020A
575
60
11.6 11.6 3.0 2 11.5 100 100
208 33.6 41.0 5.8 3 23.7 278 350
230 33.6 41.0 5.8 3 21.4 278 350
460 16.5 21.8 2.8 3 10.7 127 158
025A
575
60
13.7 17.3 3.0 3 11.5 100 125
208 41.0 41.0 5.8 3 23.7 350 350
230 41.0 41.0 5.8 3 21.4 350 350
460 21.8 21.8 2.8 3 10.7 158 158
028A
575
60
17.3 17.3 3.0 3 11.5 125 125
208 52.6 52.6 5.8 3 23.7 425 425
230 52.6 52.6 5.8 3 21.4 425 425
460 23.7 23.7 2.8 3 10.7 187 187
033A
575
60
21.7 21.7 3.0 3 11.5 148 148
208 70 70 5.8 3 23.7 448 448
230 70 70 5.8 3 21.4 448 448
460 35 35 2.8 3 10.7 225 225
039A
575
60
28 28 3.0 3 11.5 180 180
See page 20 for all Electrical Data notes.

IOMM ACZ1 ACZ 010A through 039A 19
Table 7, ACZ 010A – 039A Field Wiring Data, Single Point Power
Wiring to
Standard Power Block Terminal Wiring to Optional Disconnect Switch
ACZ
UNIT
SIZE Volts HZ. Maximum
Terminal Amps Connector Wire Range (Copper Wire Only) Disconnect Size
Connector Wire
Range
(Copper Wire Only)
208 175 14 GA – 2/0 100 8 GA – 2/0
230 175 14 GA – 2/0 100 8 GA – 2/0
460 175 14 GA – 2/0 45 14 GA – 4 GA
010A
575
60
175 14 GA – 2/0 63 14 GA – 1 GA
208 175 14 GA – 2/0 100 8 GA – 2/0
230 175 14 GA – 2/0 100 8 GA – 2/0
460 175 14 GA – 2/0 45 14 GA – 4 GA
013A
575
60
175 14 GA – 2/0 63 14 GA – 1 GA
208 175 14 GA – 2/0 100 8 GA – 2/0
230 175 14 GA – 2/0 100 8 GA – 2/0
460 175 14 GA – 2/0 45 14 GA – 4 GA
016A
575
60
175 14 GA – 2/0 63 14 GA – 1 GA
208 175 14 GA – 2/0 175 6GA – 300 kcmil
230 175 14 GA – 2/0 175 6GA – 300 kcmil
460 175 14 GA – 2/0 45 14 GA – 4 GA
020A
575
60
175 14 GA – 2/0 63 14 GA – 1 GA
208 175 14 GA – 2/0 200 6GA – 300 kcmil
230 175 14 GA – 2/0 200 6GA – 300 kcmil
460 175 14 GA – 2/0 100 8 GA – 2/0
025E
575
60
175 14 GA – 2/0 160 8 GA – 1/0
208 175 14 GA – 2/0 200 6GA – 300 kcmil
230 175 14 GA – 2/0 200 6GA – 300 kcmil
460 175 14 GA – 2/0 100 8 GA – 2/0
028A
575
60
175 14 GA – 2/0 160 8 GA – 1/0
208 175 14 GA – 2/0 200 6GA – 300 kcmil
230 175 14 GA – 2/0 200 6GA – 300 kcmil
460 175 14 GA – 2/0 100 8 GA – 2/0
033E
575
60
175 14 GA – 2/0 160 8 GA – 1/0
208 335 6 GA – 400 kcmil 200 6GA – 300 kcmil
230 335 6 GA – 400 kcmil 200 6GA – 300 kcmil
460 175 14 GA – 2/0 175 6GA – 300 kcmil
039A
575
60
175 14 GA – 2/0 175 6GA – 300 kcmil
See page 20 for all Electrical Data notes.

20 ACZ 010A through 039A IOMM ACZ1
Notes for “Electrical Data”
1. Field Fuse Size for recommended and maximum is based on use of a time-delay fuse.
2. 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.
3. Since the control transformer is furnished, no separate 115V power is required.
4. If a separate 115V power supply is used for the control circuit, the wire sizing amps is 10 Amps.
5. Recommended power lead wire sizes for three 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 should be kept short. All terminal block connections must be
made with copper (type THW) wire.
6. Single conductors should be used for power connections as listed under “Power Supply/Field
Wire Size.”
7. “Recommended Fuse Sizes” are selected at approximately 150% to 175% of the largest
compressor RLA, plus 100% of all other loads in the circuit.
8. “Maximum Fuse Sizes” are selected at approximately 225% of the largest compressor RLA, plus
100% of all other loads in the circuit.
9. 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% 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.
Notes for “Field Wiring Data” - Single Point Power:
1. Single point power supply 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 non-fused disconnect switch must be copper.
3. All field wire size values given in table apply to 75°C rated wire per NEC.