McQuay PM AGZ-2 User manual

Product Manual PM AGZ-2
Group: Chiller
Effective: May 1999
Supersedes: PM AGZ-1
© 1997 McQuay International
Air-Cooled Scroll Compressor Chiller
AGZ 030AS - 065AS, Packaged Chiller
AGZ 030AM – 050AM, Chiller with Remote Evaporator
60 Hertz, R-22

2AGZ 030A through 065A Product Manual AGZ-2
Table of Contents
Introduction...................................................................................................3
Features and Benefits....................................................................................3
DesignAdvantages........................................................................................4
Selection Procedure.....................................................................................10
Packaged Chiller, Model AS..................................................................................................................10
Remote Evaporator, Model AM ............................................................................................................12
Application Adjustment Factors..................................................................14
Performance Data........................................................................................17
Part Load Data.............................................................................................19
Sound Data..................................................................................................20
Pressure Drop Curves..................................................................................23
Electrical Data.............................................................................................24
Physical Data...............................................................................................30
AGZ-AS..................................................................................................................................................30
AGZ-AM.................................................................................................................................................32
Dimensional Data........................................................................................33
Application Data..........................................................................................36
Optional Features........................................................................................39
MicroTech...............................................................................................................................................40
Product Specification ..................................................................................41
Our facility is ISO9002 Certified
"McQuay" is a registered trademark of McQuay International
1997 McQuay International
"Illustrations cover the general appearance of McQuay International products at the time of publication and we
reserve the right to make changes in design and construction at anytime without notice"
NOTE: The Model AGZ 030AM through
AGZ 050AM chillers with remote
evaporators are not included in the ARI
Certification Program.

Product Manual AGZ-2 AGZ 030A through 065A 3
Introduction
McQuay offers air-cooled chillers from 10 through 425 tons (35 – 1500 kW). This
manual covers two varieties of the scroll compressor, air-cooled Global Chiller Line:
AGZ 030AS through AGZ 065AS, Packaged Air-Cooled Chillers
AGZ 030AM through AGZ 050AM, Air-Cooled with Remote Evaporator.
Nomenclature
AGZ- XXX AS
AGZ AS Models ARI 550/590-98 Certified
Features and Benefits
Efficiency •Cross-circuit compressor staging
•Copeland tandem scroll compressors
•Exceeds ASHRAE Std 90.1 for efficiency
Reliability •Rugged compressor design
•Factory installed operating and safety
controls
•Code and agency approval
Flexibility •Complete factory assembly
•Sizes available in 5 ton increments
•All sizes available from stock
•SpeedTrol (optional)
•Small footprint
Serviceability •Dual refrigerant circuits
•Easy servicing -- Electrical and refrigerant
components are readily accessible
•Two control options
Air-Cooled
Global
Scroll Compressor Design Vintage
Model Size
Application
S= Standard Cooling
M= Remote Evaporator

4AGZ 030A through 065A Product Manual AGZ-2
Design Advantages
The McQuay AGZ Air-Cooled Global Chiller is a product of the McQuay commitment to
offer quiet, reliable, energy efficient equipment. An approach incorporating high quality
compressors, state-of-the-art coil design, and innovative packaging.
Construction
Factory assembled and mounted on heavy-gauge painted phosphatized galvanized steel channel base.
This base distributes the unit weight for roof loading. Varied and convenient installation is possible by
virtue of the units small footprint.
Compressors
Copeland’s Compliant Scrolltandem compressors are used. These rugged hermetic compressors are
constructed with an integral cast iron frame, cast iron scrolls, three Teflon impregnated bearings, and
three oil filtration devices for each compressor.
Using Copeland's Compliant Scroll tandems provides four steps of modulation. One through four
compressors can run, depending on the load of the system, resulting in excellent part-load efficiency.
Each refrigerant circuit has two specially designed oil and gas equalization lines to control oil
migration.
The design also offers radial and axial compliance (no tip seals), a large internal volume for liquid
handling, a removable suction screen, and a rotary dirt trap and oil screen. In addition, the compressor
is self-compensating for wear, handles liquid and debris, and inherently yields the highest efficiency for
its class.
A fail-safe compressor by design-includes a solid state motor protection module, 4 individual motor-
winding sensors, a patented internal discharge temperature probe, and a patented shutdown feature that
prevents reverse rotation. An internal discharge check valve helps prevent shutdown noise and comes
standard with high and low pressure taps with Schrader valves, a sight glass, an oil level adjustment
valve, and an off cycle crankcase heater.
Units are available in 60 Hertz electrical voltage configurations from 208 to 575 volt operating at
3500 RPM.
Condenser Coils
Condenser coils have internally enhanced seamless copper tubes arranged in a staggered row pattern.
The coils are mechanically expanded into McQuay lanced and rippled aluminum fins with full fin
collars. An integral subcooler circuit provides subcooling to effectively eliminate the possibility of
liquid flashing. The external condenser coils are fitted with a protective wire mesh guard.
Condenser Fans and Motors
Multiple direct drive dynamically balanced propeller fans operate in formed venturi openings at low tip
speeds for maximum efficiency and minimum noise and vibration. A heavy-gauge vinyl-coated fan
guard protects each fan.
Each condenser fan motor is heavy-duty, 3-phase with permanently lubricated ball bearings and
inherent overload protection. SpeedTrol option includes a single-phase motor with fan speed control
on the lead fan for each circuit. Totally enclosed fan motors are available as an option on all sizes.

Product Manual AGZ-2 AGZ 030A through 065A 5
Evaporator
The evaporator is direct expansion, shell-and-tube type with water flowing in the baffled shell side and
refrigerant flowing through the tubes. Two independent refrigerant circuits within the evaporator
serve the units dual refrigerant circuits.
The evaporator has a carbon steel shell and seamless high efficiency copper tubes roller expanded into
a carbon steel tube sheet. Water baffles are polypropylene to resist corrosion.
Refrigerant heads are carbon steel with multi-pass baffles to ensure oil return and are removable to
permit access to the tubes from either end. For water removal, 3/8" (10mm) vent and drain plugs are
provided on the top and bottom of the shell.
The evaporator is wrapped with an electric resistance heater cable and insulated with 3/4" (19mm)
thick vinyl nitrate polymer sheet insulation, protecting against water freeze-up at ambient air
temperatures to -20°F (-29°C). An ambient air thermostat controls the heater cable.
The fitted and glued in place insulation has a K factor of 0.28 at 75°F (23°C).
The refrigerant (tube) side maximum working pressure is 225 psig (1552 kPa). The water side
working pressure is 175 psig (1207 kPa). Each evaporator is designed, constructed, inspected, and
stamped according to the requirements of the ASME Boiler and Pressure Vessel Code. Double
thickness insulation is available as an option.
On Model AGZ ---AM units the evaporator is shipped separate for field mounting and piping to the
outdoor unit. The refrigeration piping specialties shown in Figure 1are furnished and installed by the
installing contractor.
NOTE: A water flow switch or both water flow switch and water pump starter interlock, must be
field installed and wired to protect against evaporator freeze-up under low water flow conditions.
Figure 1, AGZ ---AM Remote Evaporator Piping Schematic (one of two circuits
shown)

6AGZ 030A through 065A Product Manual AGZ-2
Electrical Control Center
Operating and safety controls and motor starting components are separately housed in a centrally
located, weatherproof control panel with hinged and key locked doors. In addition to one of the three
types of control described in the next sections, the following components are housed in the panel:
•Power terminal block, single point standard
•Control, input, and output terminal block
•Control transformer
•Optional disconnect switch with through-the-door handle
•Compressor contactors (circuit breakers are available as an option) Compressor motor inherent
thermal and overload protection is standard
•Phase voltage monitor with under/over/phase reversal protection
•Fan contactors with separate fuse blocks
•Optional ground fault protection
•The standard FanTrol system controls fan staging for control of refrigerant discharge pressure.
The FanTrol system cycles condenser fans based on discharge pressure and outdoor temperature
and is suited for operation to 40°F (4.4°C).
•The optional SpeedTrol control uses both fan cycling and fan speed control on the lead fan per
circuit and allows operation to 0°F (-18°C) outdoor temperature.
•Mechanical high pressure cutout
Global UNT Control (Standard)
Microprocessor based control that accomplishes unit capacity control by 4-stage cross-circuit
compressor cycling based on leaving chilled water temperature. Set point and control band are easily
field adjusted. Anti-cycling and stage delay relays are included. Safety controls include low and high
refrigerant pressure, low evaporator flow, sensor failures, and evaporator freeze protection. Motor
protection includes phase voltage, volts ratio, and solid state compressor motor protection. Outside
air reset using a 4-20ma signal is standard. Return water reset, demand limit reset and remote reset
using a 4 to 20 ma signal are available options.
On remote evaporator models AGZ ---AM the leaving chilled water sensor is wired to the unit control
panel and comes with 30 feet (10 m) of cable to enable placing the bulb in the thermowell of the
evaporator. If the distance is greater than 30 feet (10 m), a field splice is required.
Figure 2, Standard Global UNT Controller

Product Manual AGZ-2 AGZ 030A through 065A 7
Global UNT with Optional Zone Terminal
Provides for onboard (or remotely wired) monitoring or adjusting of certain functions.
•Monitoring
•Monitor up to three setting or sensed values
•Monitor 18 different on/off inputs
•Monitor alarm status via a flashing alarm light and flashing symbol
•Adjusting, allows adjustment of any flashing set points, three at a time, typically set up so that the
relationship between values can be viewed simultaneously. For example
•Display 1 = Lvg Water temp
•Display 2 = Lvg Water SP
•Display 3 = % Unit Load

8AGZ 030A through 065A Product Manual AGZ-2
Figure 3, Optional Zone Terminal Configuration
MONITOR
ADJUST
TIME SCHEDULE
PASSWORD
ENTER
Compressor 1
Compressor 2
Stage 3
Stage 4
Solenoid #1
Frzstat#1Alm
Frzstat#2Alm
MinLowPres#1
MinLowPres#2
Occupied
Flow Failure
OA Lockout
Cir#2Lead=On
Pmp/Stp #1=0
Lvg Water Temp
Evap Pres #1
Evap Pres #2
OA/AI3 Input
LvgWtr RBnd SP
Contrl Band SP
Actual Lvg SP
Unoccpd Lvg SP
OA Lockout SP
Lvg Low Lim SP
SoftSta Capcty
Cir #1 Starts
Cir #2 Starts
McQuay AGZ/AGR Global Chiller
INSERT 10 ON OFF
Display
Button1
Mode
Selector
Panel
Mode
Selector
Button
2
AGZ-AGR
DisplayIndicatorDotOn/Off Status
3
Operating Mode Indicator
Up/Down Arrow Keys
Door
DisplayItemListWarningSignal
ALARM
OA/AI3 HiLimSP
OA/AI3 ResetSP
Display Area 11
Display Area 21
Display Area 31
Alarm Light
Lvg Water SP
%Unit Load
SoftStart Time
Pmp/Stp #2=0
Solenoid #2
Stage 5Opt.
Stage 6Opt.

Product Manual AGZ-2 AGZ 030A through 065A 9
MicroTech Control (optional)
Exclusive microprocessor control common throughout McQuay equipment. The interface is a 12 key
keypad and 2-line, 16 character backlit liquid crystal display in plain English. The MicroTech
continuously performs self-diagnostic checks on all system temperatures, pressures, and safeties, and
will automatically shut down a circuit or the entire unit at fault conditions, and close a set of alarm
contacts. The cause, time, and date of the occurrence, as well as important operating conditions, are
recorded and can be displayed by pressing the “Alarm” button.
Enhanced head pressure control logic results in increased SEER during transitional seasons.
Critical shutdown alarms such as high condenser pressure (with mechanical back up), freeze
protection, and low evaporator pressure are manual reset and must be cleared at the keypad to resume
operation.
Tampering is eliminated by use of password protection against unauthorized changing of setpoints and
other control parameters.
An optional modem kit and software package allows remote monitoring and control of the chiller
from an off-site PC via a direct dial telephone line.
Choose the MicroTech control and Open Protocol options to interface with virtually any building
management system and perform remote monitoring and control by hard wiring or modem.
On remote evaporator models AGZ---AM the leaving chilled water sensor is wired to the unit control
panel and comes with 30 feet (10 m) of cable to enable placing the bulb in the thermowell of the
evaporator. If the distance is greater than 30 feet (10 m), a field splice is required.
Figure 4, Optional MicroTech Control Panel

10 AGZ 030A through 065A Product Manual AGZ-2
Selection Procedure
Packaged Chiller, Model AS
Selection with Inch-Pound (I-P) units
Table 9 covers the range of leaving evaporator water temperatures and outside ambient temperatures
included under ARI 550/590-98. The tables are based on a 10 degree F (5.5 degree c) temperature
drop through the evaporator. Adjustment factors for applications having other than a 10 degree F (5.5
degree C) drop can be found in Table 3. The minimum leaving chilled water temperature setpoint
without glycol is 40°F (4°C) . For brine selections, see Table 1 for ethylene or Table 2 for propylene
glycol adjustment factors. Ratings are based on a 0.0001 fouling factor in the evaporator at sea level
operation. For other fouling factors, different delta-Ts, or altitude correction factors see Table 3. For
applications outside the catalog ratings contact your local McQuay sales representative.
Selection example
Given:
50 tons minimum
95°F ambient temperature
120 gpm, 54°F to 44°F chilled water
0.0001 evaporator fouling factor
1. From Performance Table 9, an AGZ 055AS at the given conditions will produce 54.0 tons with a
compressor kW input of 59.0 and a unit EER of 9.9.
2. Use the following formula to calculate any unknown elements.
gpm=
24
F
tons
°×
3. Determine the evaporator pressure drop. Using Figure 8, enter at 120 gpm and follow up to the
AGZ 055AS line intersect. Read horizontally to obtain an evaporator pressure drop of 14.0 feet
of water.
Selection example using ethylene glycol
Given:
45 tons minimum
95°F ambient air temperature
54°F - 44°F chilled water temperature
0.0001 evaporator fouling factor
Protect from freezing down to 0°F
1. From Table 1, select an ethylene glycol concentration of 40% to protect against freezing at 0°F.
2. At 40% ethylene glycol, the adjustment factors are: Capacity =0.961, kW = 0.976,
GPM = 1.121, pressure drop = 1.263
3. Select the AGZ 050AS and correct with 40% ethylene glycol factors.
4. Correct capacity = 0.961 X 49.0 tons = 47.1 tons
5. Correct compressor kW = 0.976 X 52.6 kW = 51.3 kW
6. Calculate chilled water flow:
gpm113.0=
10 241.47
=capacity)corrected(atflowWater F
tons
°×
Glycol flow (at 40% solution) = 1.121 X 113.0 gpm = 126.2 gpm