McQuay AWS 175A Installation Manual
Operating & Maintenance Manual
Pathfinder™ Air-Cooled Chillers
AWS 175A through AWS 515A
Software Version A
50/60 Hertz,
R-134a
OMM 998
Group: Chiller
Part Number: 10000199900
Date: June 2009
Supercedes: New
© 2009 McQuay International
Table of Contents
INTRODUCTION........................................................3
OPERATING LIMITS:...............................................4
CONTROLLER FEATURES .....................................4
GENERAL DESCRIPTION........................................5
CONTROL PANEL LAYOUT ..........................................6
POWER PANEL LAYOUT ..............................................7
ECONOMIZER COMPONENTS .......................................8
CONTROLLER DESCRIPTION.............................10
HARDWARE STRUCTURE...........................................10
SYSTEM ARCHITECTURE...........................................11
SEQUENCE OF OPERATION ................................12
CONTROLLER OPERATION.................................16
MICROTECH III INPUTS/OUTPUTS.............................16
EXTENSION I/O COMPRESSOR #1 TO #3....................17
I/O EXV CIRCUIT #1 TO #3.......................................17
EXTENSION I/O FAN MODULE CIRCUIT #1 & 2.........18
EXTENSION I/O FAN MODULE CIRCUIT #3................18
EXTENSION I/O UNIT ALARM & LIMITING (POL......18
SETPOINTS ................................................................19
UNIT FUNCTIONS....................................................24
CALCULATIONS.........................................................24
UNIT ENABLE ...........................................................24
UNIT MODE SELECTION............................................24
UNIT CONTROL STATES............................................25
UNIT STATUS ............................................................26
ICE MODE START DELAY..........................................26
EVAPORATOR PUMP CONTROL .................................27
NOISE REDUCTION....................................................27
LEAVING WATER TEMPERATURE (LWT) RESET.......28
UNIT CAPACITY CONTROL........................................30
UNIT CAPACITY OVERRIDES ....................................32
CIRCUIT FUNCTIONS...........................................34
CALCULATIONS........................................................ 34
CIRCUIT CONTROL LOGIC........................................ 35
CIRCUIT STATUS ......................................................36
COMPRESSOR CONTROL........................................... 36
CONDENSER FAN CONTROL..................................... 38
EXV CONTROL ........................................................ 40
ECONOMIZER CONTROL........................................... 41
LIQUID INJECTION.................................................... 41
ALARMS AND EVENTS......................................... 42
SIGNALING ALARMS ................................................ 42
CLEARING ALARMS ................................................. 42
DESCRIPTION OF ALARMS........................................ 43
UNIT EVENTS........................................................... 45
CIRCUIT STOP ALARMS............................................ 46
CIRCUIT EVENTS...................................................... 50
ALARM LOGGING..................................................... 52
USING THE CONTROLLER.................................. 53
NAVIGATING............................................................ 54
OPTIONAL REMOTE USER INTERFACE......... 61
START-UP AND SHUTDOWN............................... 63
TEMPORARY SHUTDOWN ......................................... 63
EXTENDED (SEASONAL) SHUTDOWN ....................... 64
FIELD WIRING DIAGRAM................................... 66
SYSTEM MAINTENANCE..................................... 68
PREVENTATIVE MAINTENANCE SCHEDULE.............. 72
APPENDIX ................................................................ 73
DEFINITIONS ............................................................ 73
Manufactured in an ISO Certified facility
2009 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. The following are trademarks or registered trademarks of
their respective companies: BACnet from ASHRAE; L
Guardister, and Open Choice from McQuay International.
2 OMM 998
ONMARK and LONWORKS from Echelon Corporation; McQuay, MicroTech III,
Unit controllers are LONMARK
certified with an optional
communications module
LONWORKS
Introduction
This manual provides setup, operating, troubleshooting and maintenance information for the
Daiken McQuay Pathfinder chillers.
Dangers indicate a hazardous situation which will result in death or seriou s injury if not avoided.
Warnings indicate potentially hazardous situations, which can result in property damage, severe
Cautions indicate potentially hazardous situations, which can result in persona l injury or
Software Version: This manual covers units with Software Version XXXXXXX The unit’s
software version number can be viewed by pressing the MENU and ENTER keys (the two
right keys) simultaneously. Then, pressing the MENU key will return to the Menu screen.
BOOT Version: XXX
HAZARD IDENTIFICATION INFORMATION
!
DANGER
!
WARNING
personal injury, or death if not avoided.
!
CAUTION
equipment damage if not avoided.
BIOS Version: XXX
!
WARNING
Electric shock hazard: can cause personal injury or equipment damage. This equipment must be
properly grounded. Connections to, and service of, the MicroTech III control panel must be
performed only by personnel who are knowledgeable in the operation of this equipm ent .
!
CAUTION
Static sensitive components. A static discharge while handling electronic circuit boards can cause
damage to the components. Discharge any static electrical charge by touching the bare metal
inside the control panel before performing any service work. Never unplug any cables, circuit
board terminal blocks, or power plugs while power is applied to the panel.
NOTICE
This equipment generates, uses, and can radiate radio frequency energ y and, if not installed and
used in accordance with this instruction manual, can cause interference to radio
communications. Operation of this equipment in a residential area can cause harmful
interference, in which case the user will be required to correct the interference at the user’s own
expense. McQuay International Corporation disclaims any liability resulting from any
interference or for the correction thereof.
OMM 998 3
Operating Limits:
Maximum standby ambient temperature, 130F (55C)
Maximum operating ambient temperature is 115F (46C), or 125F (52C) with the
addition of the optional high ambient package
Minimum operating ambient temperature (standard), 35F (2C)
Minimum operating ambient temperature (with optional low-ambient control), 0F (-18C)
Leaving chilled water temperature, 40F to 60F (4.4C to 15.6C)
Leaving chilled fluid temperatures (with anti-freeze), 30F to 60F (-2C to 16C).
Unloading is not permitted with fluid leaving temperatures below 30F (-1C).
Operating Delta-T range, 6F to 16F (3.3C to 8.9C)
Maximum operating inlet fluid temperature, 76F (24C)
Maximum non-operating inlet fluid temperature, 100F (38C)
Controller Features
Readout of the following temperature and pressure readings:
Entering and leaving chilled water temperature
Saturated evaporator refrigerant temperature and pressure
Saturated condenser temperature and pressure
Outside air temperature
Suction line, liquid line, and discharge line temperatures calculated superheat for
discharge and suction lines
Oil pressure
Automatic control of primary and standby chilled water pumps. The control will start one of
the pumps (based on lowest run-hours) when the unit is enabled to run (not necessarily
running on a call for cooling) and when the water temperature reaches a point of freeze
possibility.
Two levels of security protection against unauthorized changing of setpoints and other control
parameters.
Warning and fault diagnostics to inform operators of warning and fault conditions in plain
language. All events and alarms are time and date-stamped for identification of when the
fault condition occurred. In addition, the operating conditions that existed just prior to an
alarm shutdown can be recalled to aid in isolating the cause of the problem.
Twenty-five previous alarms and related operating conditions are available.
Remote input signals for chilled water reset, demand limiting, and unit enable.
Test mode allows the service technician to manually control the controllers’ outputs and can
be useful for system checkout.
Building Automation System (BAS) communication capability via LonTalk, Modbus, or
BACnet standard protocols for all BAS manufacturers-simplified with McQuay’s Open
Choices feature.
Pressure transducers for direct reading of system pressures. Preemptive control of low
evaporator pressure conditions and high discharge temperature and pressure to take corrective
action prior to a fault trip.
4 OMM 998
General Description
The control panel is located on the front of the unit at the compressor end. There are three
doors. The control panel is behind to left-hand door. The power panel is behind the middle
and right-hand doors.
General Description
The MicroTech III control system consists of a microprocessor-based controller and a
number of extension modules, which vary depending on the unit size and conformation.
The control system provides the monitoring and control functions required for the
controlled, efficient operation of the chiller.
The operator can monitor all critical operating conditions by using the screen located on
the main controller. In addition to providing all normal operating controls, the MicroTech
III control system will take corrective action if the chiller is operating outside of its normal
design conditions. If a fault condition develops, the controller will shut a compressor, or
the entire unit, down and activate an alarm output. .
The system is password protected and only allows access by authorized personnel. Except
that some basic information is viewable and alarms can be cleared without a password. No
settings can be changed.
OMM 998 5
Control Panel Layout
Figure 1, Control Panel Components
Controller
Fuse
Emergency
Switch
Relay
Control
Circuit
Breaker
Unit On/Off
Switch
Circuit #1
Pumpdown
Switch
Circuit #2
Pumpdown
Switch
Alarm & Limit
Extension
Module
MicroTech III
Main
Controller
Optional
115V
Outlet
Cir #1 & #2
Fan Control
Extension
Module
NOTES:
1. The Emergen cy Switch Relay de-energizes circuit #1 and #2 control power when activated,
causing an immediate compressor and fan shutdown. The red emergency button switch is
located on the bottom front of the control panel door.
2. The control power transformer is located in th e power panel adjacent to the control panel.
3. Additional extension (aka extension) modules are located elsewhere on the chiller.
6 OMM 998
p
Phase/Voltage
r
r
Fan Contactors
er Fan, Circuit #2
1
120/24V
Transforme
Line/120V
Transformer
Power Panel Layout
The power panel is at the front of the unit, behind the two doors to the right.
Figure 2, Power Panel, Left Side
Fan Contactors, 1 per Fan
Circuit #1
Monitor
Cir# 1, Fan Circuit Breaker
Compressor #1
Circuit Breaker
Figure 3, Power Panel, Right Side
Compressor #2
Circuit Breake
OMM 998 7
Economizer Components
The chiller may or may not have economizers depending on design capacity
requirements. An economizer is a well-proven device to increase a refrigerant
circuit’s capacity and to a lesser extent, its efficiency.
Figure 4, Economizer Components
Brazed-plate Heat
Exchanger
Gas to Comp.
Interstage
Liquid from
Condenser
TXV LLSV
Warm liquid from the condenser is feed into the economizer where it is cooled by flashing
off liquid also from the condenser. The flash gas is piped to a compressor interstage point.
Lowering the liquid refrigerant temperature to the evaporator decreases its enthalpy (heat
content) and results in a greater amount of heat absorption from the chilled water.
8 OMM 998
Liquid Feed
to
Economizer
Liquid Feed
to
Evaporator
Figure 5, Piping Schematic with Economizer Circuit, One Circuit
Figure 6, Piping Schematic without Economizer Circuit, One Circuit
OMM 998 9
Controller Description
Hardware Structure
The MicroTech III control sy stem for Pathfinder chillers consists of a main unit controller with
a number of extension I/O modules attached depending on the chiller size and configuration.
One of the optional BAS communication modules may be included.
An optional Remote Operator Interface panel may be included, connected with up to nine
PATHFINDER units.
The Advanced MicroTech III controllers used on PATHFINDER chillers are not interchangeable
with previous MicroTech II controllers.
MicroTech III Unit Controller
Remote Operator Interface
BACnet/
MSTP
Communication
MODbus LON
BACnet/IP
AWC
Extension I/O Modules
10 OMM 998
System Architecture
The overall controls architecture uses the following:
One Microtech III main controller
I/O extension modules (sometimes referred to as “controllers”) as needed
depending on the configuration of the unit
Optional BAS interface as selected
Figure 7, System Architecture
BAS Interface
(Bacnet, Lon,
Modbus)
Microtech III Main Controller
Peripheral Bus
I/O Extension
Alarm/Limiting
I/O Extension
Compressor 1
I/O Extension
Compressor 2
I/O Extension
Compressor 3
I/O Extension
Fans Circuit 1
and 2
I/O Extension
EXV 1
I/O Extension
EXV 2
I/O Extension
EXV 3
I/O Extension
Fans Circuit 3
I/O Extension
Fans Circuit 3
and 4
I/O Extension
Fans Circuit 4
I/O Extension
Compressor 4
I/O Extension
EXV 4
OMM 998 11
Sequence of Operation
Figure 8, Unit Sequence of Operation (see Figure 9 for circuit sequence of operation)
Unit power up
Unit in Off state
Is unit enabled?
Yes
Is low ambient lockout
active?
No
Evaporator pump output on
AWS Chiller Sequence of Operation in Cool Mode
The chiller may be disabled via the unit switch, the remote switch, the keypad
No
enable setting, or the BAS network. In addition, the chiller will be disabled if all
circuits are disabled, or if there is a unit alarm. If the chiller is disabled, the unit
status display will reflect this and also show why it is disabled.
If the unit switch is off, the unit status will be Off:Unit Switch. If the chiller is
disabled due to network command, the unit status will be Off:BAS Disable. When
Yes
the remote switch is open, the unit status will be Off:Remote Switch. When a unit
alarm is active, the unit status will be Off:Unit Alarm. In cases where no circuits
are enabled, the unit status will be Off:All Cir Disabled. If the unit is disabled via
the Chiller Enable set point, the unit status will be Off:Keypad Disable.
Low ambient lockout will prevent the chiller from starting even if it is otherwise
enabled. When this lockout is active, the unit status will be Off:Low OAT Lock.
If the chiller is enabled, then the unit will be in the Auto state and the evaporator
water pump output will be activated.
No
Is flow present?
Yes
Wait for chilled water loop to
recirculate.
Keep pump output on while
chiller is enabled and either
running or ready to run.
Is there enough load to
start chiller?
Yes
The chiller will then wait for the flow switch to close, during which time the unit
status will be Auto:Wait for flow.
After establishing flow, the chiller will wait some time to allow the chilled water loop
to recirculate for an accurate reading of the leaving water temperature. The unit
status during this time is Auto:Evap Recirc.
No
The chiller is now ready to start if enough load is present. If the LWT is not higher
than the Active Setpoint plus the Start Up Delta T, the unit status will be Auto:Wait
for load.
If the LWT is higher than the Active Setpoint plus the Start Up Delta T, the unit
status will be Auto. A circuit can start at this time.
12 OMM 998
OMM 998 13
Load/unload as needed to
satisfy load.
Is load satisfied?
The remaining running circuit(s) will be loaded/unloaded as needed to satisfy the
load.
No
When only one circuit is running, the load may drop off to the point where even
minimum unit capacity is too much. The load has been satisfied when the LWT
drops below the Active Setpoint minus the Shutdown Delta T. At this time the only
running circuit can shut down.
Yes
Shut down last circuit.
The last circuit running now shuts down.
The unit should be ready to start again when the LWT gets high enough. Until that
time, unit status will be Auto:Wait for load.
14 OMM 998
Figure 9, Circuit Sequence of Operation
Unit power up
Circuit is in Off state
Is circuit is enabled to
start?
Yes
Are compressor cycle
timers active?
No
Is compressor oil sump
ready?
No
AWS Sequence of Operation - Circuits
When the circuit is in the Off state the EXV is closed, compressor is off, and all fans
are off.
The circuit must be enabled before it can run. It may be disabled for several
reasons. When the circuit switch is off, the status will be Off:Circuit Switch.
If the BAS has disabled the circuit, the status will be Off:BAS Disable. If the circuit
Yes
has an active stop alarm then the status will be Off:Cir Alarm. If the circuit has
been disabled via the circuit mode set point, the status will be Off:Cir Mode
Disable.
No
A minimum time must pass between the previous start and stop of a compressor
and the next start. If this time has not passed, a cycle timer will be active and the
circuit status will be Off:Cycle Timer.
If the compressor is not ready due to refrigerant in the oil, the circuit cannot start.
The circuit status will be Off:Refr In Oil.
Yes
Circuit is ready to start
Is circuit commanded to
start?
Yes
Run circuit
Is circuit commanded to
shut down?
Yes
Pumpdown circuit
If the compressor is ready to start when needed, the circuit status will be
Off:Ready.
No
When the circuit begins to run, the compressor will be started and the EXV, fans,
and other devices will be controlled as needed. The normal circuit status at this
time will be Run.
No
When the circuit is commanded to shut down, a normal shut down of the circuit will
be performed. The circuit status during this time will be Run:Pumpdown. After
the shut down is completed, the circuit status will normally be Off:Cycle Timer
initially.
OMM 998 15
Controller Operation
MicroTech III Inputs/Outputs
I/O for the unit control and for circuits one and two are found on CP1.
The chiller may be equipped with two or three compressors.
Analog Inputs
# Description Signal Source Expected Range
AI1 Evaporator Entering Water Temp NTC Thermister (10K@25°C) -50°C – 120°C
AI2 Evaporator Leaving Water Temp NTC Thermister (10K@25°C) -50°C – 120°C
AI3 Evaporator #1 Leaving Water Temp (*) NTC Thermister (10K@25°C) -50°C – 120°C
X1 Evaporator #2 Leaving Water Temp (*) NTC Thermister (10K@25°C) -50°C – 120°C
X2 Outside Ambient Temperature NTC Thermister (10K@25°C) -50°C – 1 20°C
X4 LWT Reset 4-20 mA Current 1 to 23 mA
Analog Outputs
# Description Output Signal Range
X5 Fan VFD #1 0-10VDC 0 to 100% (1000 steps resolution)
X6 Fan VFD #2 0-10VDC 0 to 100% (1000 steps resolution)
X7 Fan VFD #3 0-10VDC 0 to 100% (1000 steps resolution)
X8 Fan VFD #4 0-10VDC 0 to 100% (1000 steps resolution)
Digital Inputs
# Description Signal Off Signal On
DI1 Unit PVM Fault No Fault
DI2 Evaporator Flow Switch No Flow Flow
DI3 Double Set Point/ Mode Switch Cool mode Ice mode
DI4 Remote Switch Remote off Remote on
DI5 Unit Switch Unit off Unit on
DI6 Emergency Stop Unit off/rapid stop Unit on
Digital Outputs
# Description Output OFF Output ON
DO1 Evaporator Water Pump Pump Off Pump On
Alarm Active
DO2 Unit Alarm Alarm not Active
DO3 Circuit #1 Fan Step #1 Fan Off Fan On
DO4 Circuit #1 Fan Step #2 Fan Off Fan On
DO5 Circuit #1 Fan Step #3 Fan Off Fan On
DO6 Circuit #1 Fan Step #4 Fan Off Fan On
DO7 Circuit #2 Fan Step #1 Fan Off Fan On
DO8 Circuit #2 Fan Step #2 Fan Off Fan On
DO9 Circuit #2 Fan Step #3 Fan Off Fan On
DO10 Circuit #2 Fan Step #4 Fan Off Fan On
(Flashing= circuit
alarm)
16 OMM 998
Extension I/O Compressor #1 to #3
Analog Inputs
# Description Signal Source Expected Range
X1 Discharge Temperature NTC Thermister (10K@25°C) -50°C – 120°C
X2 Evaporator Pressure Ratiometric (0,5-4,5 Vdc) 0 to 5 Vdc
X3 Oil Pressure Ratiometric (0,5-4,5 Vdc) 0 to 5 Vdc
X4 Condenser Pressure Ratiometric (0,5-4,5 Vdc) 0 to 5 Vdc
X7 Motor Protection NTC Thermister (10K@25°C) n/a
Analog Outputs
# Description Output Signal Range
Not Needed
Digital Inputs
# Description Signal Off Signal On
X6 Starter Fault Fault No fault
DI1 High Pressure Switch Fault No fault
Digital Outputs
U.S. Configuration
# Description Output Off Output On
DO1 Start Compressor Compressor Off Compressor On
DO2 Economizer Solenoid Closed Solenoid Open
DO3 Non-modulating Slide Load Solenoid Closed Solenoid Open
DO4 Non-modulating Slide Unload Solenoid Closed Solenoid Open
DO5 Modulating Slide Load Solenoid Closed Solenoid Open
DO6 Modulating Slide Unload Solenoid Closed Solenoid Open
X5 Modulating Slide ‘Turbo’ Solenoid Closed Solenoid Open
X8 Liquid Injection Solenoid Closed Solenoid Open
I/O EXV Circuit #1 to #3
Analog Inputs
# Description Signal Source Expected Range
X2 Suction Temperature NTC Thermister 10K@25°C) -50°C – 120°C
Analog Outputs
# Description Output Signal Range
Not Needed
Digital Inputs
# Description Signal Off Signal On
DI1 Low Pressure switch Fault No fault
Digital Outputs
# Description Output Off Output On
DO1 Liquid Line Solenoid Closed Solenoid Open
OMM 998 17
Stepper Motor Output
# Description
M1+
M1M2+
M2-
EXV Stepper Coil 1
EXV Stepper Coil 2
Extension I/O Fan Module Circuit #1 & 2
Digital Inputs
# Description Output Off Output On
DI1 PVM/GFP Circuit #1 Fault No fault
DI2 PVM/GFP Circuit #2 Fault No fault
Digital Outputs
# Description Output Off Output On
DO1 Circuit #1 Fan Step #5 Fan Off Fan On
DO2 Circuit #1 Fan Step #6 Fan Off Fan On
DO3 Circuit #2 Fan Step #5 Fan Off Fan On
DO4 Circuit #2 Fan Step #6 Fan Off Fan On
Extension I/O Fan Module Circuit #3
Digital Outputs
# Description Output Off Output On
DO1 Circuit #3 Fan Step #5 Fan Off Fan On
DO2 Circuit #3 Fan Step #6 Fan Off Fan On
Extension I/O Unit Alarm & Limiting (POL
Analog Inputs
# Description Signal Source Range
X3 Demand Limit 4-20 mA 1 to 23 mA
X4 Unit Current 4-20 mA 1 to 23 mA
Analog Outputs
# Description Output Signal Range
Not Needed
Digital Inputs
# Description Signal Off Signal On
X1 External Alarm/Event External Device Failure External Device OK
X2 Current Limit Enable No Limiting Limiting
X5 Circuit Switch #1 Circuit Off Circuit On
X6 Circuit Switch #2 Circuit Off Circuit On
X7 Circuit Switch #3 Circuit Off Circuit On
Digital Outputs
# Description Output Off Output On
DO1 Evaporator Water Pump #2 Pump Off Pump On
DO2 Open
DO3 Circuit #1 Alarm No Alarm Alarm
DO4 Circuit #2 Alarm No Alarm Alarm
DO5 Circuit #3 Alarm No Alarm Alarm
18 OMM 998
Setpoints
The following parameters are remembered during power off, are factory set to the Default
value, and can be adjusted to any value in the Range column.
Read and write access to these set points is determined by the Global HMI (Human Machine
Interface) Standard Specification.
Table 1, Setpoint Value and Range
Description Default Range
Unit Ft/Lb SI Manufacturing Location Not Selected Not Selected, Europe, USA
Unit Enable OFF OFF, ON
Unit Status after Power
Failure
Control source Local Local, Network
Available Modes Cool COOL
Cool LWT 1
Cool LWT 2
Ice LWT
Startup Delta T
Shut Down Delta T
Stage Up Delta T (between
compressors)
Stage Down Delta T
(between compressors)
Max Pulldown
Evap Recirc Timer 30 0 to 300 seconds
Evap Control #1 Only #1 Only, #2 Only, Auto,
LWT Reset Type NONE NONE, RETURN, 4-20mA, OAT
Max Reset
Start Reset Delta T
Start Reset OAT 75°F 23.8°C 50°F - 85°F / 10.0 – 29.4°C
Max Reset OAT 60°F 15.5°C 50°F - 85°F / 10.0 – 29.4°C
Soft Load Off Off, On
Begin Capacity Limit 40% 20-100%
Soft Load Ramp 20 min 1-60 minutes
Demand Limit Off Off, On
Current Limit Off Off, On
Current @ 20mA 800 Amp 0 to 2000 Amp = 4 to 20 mA
Current limit Set Point 800 Amp 0 to 2000 Amp
# of Circuits 2 2-3-4
Ice Time Delay 12 1-23 hours
Continued next page.
44 F
44 F
25 F
1.5 F
3 F/min
10 F
10 F
OFF OFF, ON
COOL/w GLYCOL
COOL/ICE w GLYCOL
7 °C
7 °C See section 0
5 F
2 F
1 F
-4 °C
2,7 °C
0,7 °C
1 °C
0,5 °C
1,7
°C/min
5 °C
5 °C
20 to 38F / -8 to 4 °C
0 to 10 F / 0 to 5 °C
0 to 3 F / 0 to 1,7 °C
0 to 3 F / 0 to 1,7 °C
0 to 3 F / 0 to 1,7 °C
0.5-5.0 F /min / 0,3 to 2,7 °C/min
#1 Primary, #2 Primary
0 to 20 F / 0 to 10 °C
0 to 20 F / 0 to 10 °C
ICE
TEST
See section 0
OMM 998 19
Description Default Range
Unit Ft/Lb SI Clear Ice Timer No No,Yes SSS Communication No No, Yes PVM Multi Point Single Point, Multi Point , None(SSS) Noise Reduction Disabled Disabled, Enabled Noise Reduction Start Time 21:00 18:00 – 23:59 Noise Reduction End Time 6:00 5:00 – 9:59 Noise Reduction Condenser
10.0 F
5 °C
0.0 to 25.0 F
Offset
BAS Protocol None None, BACnet, LonWorks, Modbus
Ident number 1 0-????
Baud Rate 19200 1200,2400,4800,9600,19200
Evap LWT sensor offset 0°F 0°C -5.0 to 5.0°C / -9.0 to 9.0°F
Evap EWT sensor offset 0°F 0°C -5.0 to 5.0°C / -9.0 to 9.0°F
OAT sensor offset 0°F 0°C -5.0 to 5.0°C / -9.0 to 9.0°F
Compressors-Global Ft/Lb SI Start-start timer 20 min 15-60 minutes Stop-start timer 5 min 3-20 minutes Pumpdown Pressure 14,3 PSI 100 KPA 10 to 40 PSI / 70 to 280 KPA Pumpdown Time Limit 120 sec 0 to 180 sec Light Load Stg Dn Point 50% 20 to 50% Load Stg Up Point 50% 50 to 100% Stage Up Delay 5 min 0 to 60 min Stage Down Delay 3 min 3 to 30 min Stage Delay Clear No No, Yes Max # Comps Running 4 1-4 Sequence # Cir 1 1 1-4 Sequence # Cir 2 1 1-4 Sequence # Cir 3 1 1-4 Number of Pulses 10% to
10 10 to 20
50%
Slide Load Delay Mininum 30 seconds 10 to 60 seconds
Slide Load Delay
150 seconds 60 to 300 seconds
Maximum
Slide Unload Delay
10 seconds 5 to 20 seconds
Minimum
Slide Unload Delay
50 seconds 30 to 75 seconds
Maximum
Liquid Injection Activation 185°F 85°C 75 to 90°C
Liquid Line Solenoid
No No, Yes
Valves
Alarm Limits
Low Evap Pressure-Unload 27.5 PSI 190 KPA See section 0
Low Evap Pressure-Hold 29 PSI 200 KPA See section 0
Oil Press Delay 30 sec 10-180 sec
Continued next page.
20 OMM 998
Description Default Range
N
Unit Ft/Lb SI Oil Press Differential 35 PSI 250 KPA 0-60 PSI / 0 to 415 KPA Low Oil Level Delay 120 sec 10 to 180 sec High Discharge Temperat.
230 F
110 °C 150 to 230 °F / 65 to 110 °C
High Lift Pressure Delay 5 sec 0 to 30 sec
Low Pressure Ratio Delay 90 sec 30-300 sec
Start Time Limit 60 sec 20 to 180 sec
Evaporator Water Freeze
36 F
2,2 °C See section 0
Evaporator Flow Proof 15 sec 5 to 15 sec
Recirculate Timeout 3 min 1 to 10 min
Low Ambient Lockout
Disable Disable, Enable
Enable
Low Ambient Lockout
55 F
12°C See section 0
The following set points exist individually for each circuit:
Description Default
Ft/Lb SI
Range
PW
Circuit mode Enable Disable, enable, test S
Compressor Size To be Verified M
Capacity Control Auto Auto, Manual S
Manual Capacity
See note 1 below table
0 to 100% S
Clear Cycle Timers No No, yes M
EXV control Auto Auto, manual S
EXV position
See note 2 below table 0% to 100%
S
Oil Sump Check Enable Enable, Disable S
Service Pumpdown No No,Yes S
Evap pressure offset 0PSI 0KPA -14.5 to 14.5 PSI /-100 to 100 KPA S
Cond pressure offset 0PSI 0KPA -14.5 to 14.5 PSI /-100 to 100 KPA S
Oil pressure offset 0PSI 0KPA -14.5 to 14.5 PSI /-100 to 100 KPA S
Suction temp offset 0°F 0°C -5.0 to 5.0 deg S
Discharge temp offset 0°F 0°C -5.0 to 5.0 deg S
Fans
Fan VFD enable On Off, On M
umber of fans 5 5 to 12 M
Saturated Condenser Temp
Target Min
Saturated Condenser Temp
Target Max
90 °F 32°C
110 °F 43°C
80.0-110.0
90.0-120.0
o
F / 26.0 to 43.0 °C
o
F / 32.0 to 50 °C
M
M
Fan Stage Up Deadband 0 5 °F 2.5 °C 1-20 oF / 1-10 °C M
Fan Stage Up Deadband 1 5 °F 2.5 °C 1-20 oF / 1-10 °C M
Fan Stage Up Deadband 2 8 °F 4 °C 1-20 oF / 1-10 °C M
Fan Stage Up Deadband 3 10 °F 5 °C 1-20 oF / 1-10 °C M
Fan Stage Up Deadband 4 8 °F 4 °C 1-20 oF / 1-10 °C M
Fan Stage Up Deadband 5 8 °F 4 °C 1-20 oF / 1-10 °C M
Fan Stage Down Deadband 2 8 °F 4 °C 1-25 oF / 1-13 °C M
Fan Stage Down Deadband 3 7 °F 3.5 °C 1-25 oF / 1-13 °C M
Fan Stage Down Deadband 4 6 °F 3 °C 1-25 oF / 1-13 °C M
Continued next page.
OMM 998 21
Fan Stage Down Deadband 5 5 °F 2.5 °C 1-25 oF / 1-13 °C M
Fan Stage Down Deadband 6 5 °F 2.5 °C 1-25 oF / 1-13 °C M
VFD Max Speed 100% 90 to 110% M
VFD Min Speed 25% 20 to 60% M
Note 1 – This value will follow the actual capacity while Capacity Control = Auto.
Note 2 – This value will follow the actual EXV position while EXV Control = Auto.
Auto Adjusted Ranges
Some settings have different ranges of adjustment based on other settings.
Cool LWT 1 and Cool LWT 2
Available Mode Selection Range Imp. Range SI
Without Glycol 40 to 60oF 4 to 15 °C
With Glycol 25 to 60oF -4 to 15 °C
Evaporator Water Freeze
Available Mode Selection Range Imp. Range SI
Without Glycol 36 to 42oF 2 to 6 °C
With Glycol 0 to 42oF -18 to 6 °C
Low Evaporator Pressure - Hold
Available Mode Selection Range Imp. Range SI
Without Glycol 28 to 45
PSIG
With Glycol 0 to 45 PSIG 0 to 310 KPA
Low Evaporator Pressure - Unload
Available Mode Selection Range Imp. Range SI
Without Glycol 26 to 45 Psig 180 to 310 KPA
With Glycol 0 to 45 Psig 0 to 410 KPA
Low Ambient Lockout
Fan VFD Range Imp. Range SI
= no for all circuits 35 to 60oF 2 to 15 °C
= yes on any circuit -10 to 60oF -23 to 15 °C
195 to 310 KPA
22 OMM 998
Dynamic Default Values
The fan staging dead bands have different default values based on the VFD enable setpoint.
When the VFD enable setpoint is changed, a set of default values for the fan staging dead
bands is loaded as follows:
F)
VFD is Disabled
Setpoint
Default
loaded (oF)
8
VFD is Enabled
Setpoint
Stage 1 On Deadband
Stage 2 On Deadband 5 Stage 2 On Deadband 10
Stage 3 On Deadband 8 Stage 3 On Deadband 11
Stage 4 On Deadband 10 Stage 4 On Deadband 12
Stage 5 On Deadband 8 Stage 5 On Deadband 13
Stage 6 On Deadband 8 Stage 6 On Deadband 13
Stage 7 On Deadband 8 Stage 7 On Deadband 13
Stage 8 On Deadband 8 Stage 8 On Deadband 13
Stage 2 Off Deadband 8 Stage 2 Off Deadband 20
Stage 3 Off Deadband 7 Stage 3 Off Deadband 16
Stage 4 Off Deadband 6 Stage 4 Off Deadband 11
Stage 5 Off Deadband 5 Stage 5 Off Deadband 8
Stage 6 Off Deadband 5 Stage 6 Off Deadband 8
Stage 7 Off Deadband 5 Stage 7 Off Deadband 8
Stage 8 Off Deadband 5 Stage 8 Off Deadband 8
Default
loaded (
o
OMM 998 23
Unit Functions
Calculations
LWT Slope
LWT slope is calculated such that the slope represents the change in LWT over a time
frame of one minute with at least five samples per minute.
Pulldown Rate
The slope value calculated above will be a negative value as the water temperature is
dropping. For use in some control functions, the negative slope is converted to a positive
value by multiplying by –1.
Unit Enable
Enabling and disabling the chiller is accomplished using set points and inputs to the
chiller. The unit switch, remote switch input, and Unit Enable Set Point all are required
to be on for the unit to be enabled when the control source is set to local. The same is
true if the control source is set to network, with the additional requirement that the BAS
request must be on.
Unit is enabled according to the following table.
NOTE: An x indicates that the value is ignored.
Unit
Switch
Off x x x x Off
x x x Off x Off
x x Off x x Off
On Local On On x On
x Network x x Off Off
On Network On On On On
All of the methods for disabling the chiller, discussed in this section, will cause a normal
shutdown (pumpdown) of any running circuits.
When the controller is powered up, the Unit Enable Set Point will be initialized to ‘off’ if
the Unit Status After Power Failure Set Point is set to ‘off’.
Control
Source Set
Point
Remote
Switch Input
Unit Enable
Set Point
BAS
Request
Unit
Enable
Unit Mode Selection
The operating mode of the unit is determined by setpoints and inputs to the chiller. The
Available Modes Set Point determines what modes of operation can be used. This
setpoint also determines whether the unit is configured for glycol use. The Control
Source Set Point determines where a command to change modes will come from. A
digital input switches between cool mode and ice mode if they are available and the
control source is set to local. The BAS mode request switches between cool mode and ice
mode if they are both available and the control source is set to network.
24 OMM 998
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