Trane WSC120E Owner's manual

January 2010 RT-SVX23E-EN
Installation
Operation
Maintenance
Packaged Heat Pump
3 Through 10 Ton
Model Numbers
WSC036E - WSC120E

© 2010 Trane. All rights reserved RT-SVX23E-EN
Warnings, Cautions and Notices
Warnings, Cautions and Notices. Note that warnings, cautions and notices appear at
appropriate intervals throughout this manual. Warnings are provided to alert installing contractors
to potential hazards that could result in personal injury or death. Cautions are designed to alert
personnel to hazardous situations that could result in personal injury, while notices indicate a
situation that could result in equipment or property-damage-only accidents.
Your personal safety and the proper operation of this machine depend upon the strict observance
of these precautions.
Important
Environmental Concerns!
Scientific research has shown that certain man-made chemicals can affect the earth's naturally
occurring stratospheric ozone layer when released to the atmosphere. In particular, several of the
identified chemicals that may affect the ozone layer are refrigerants that contain Chlorine, Fluorine
and Carbon (CFCs) and those containing Hydrogen, Chlorine, Fluorine and Carbon (HCFCs). Not all
refrigerants containing these compounds have the same potential impact to the environment.
Trane advocates the responsible handling of all refrigerants-including industry replacements for
CFCs such as HCFCs and HFCs.
Responsible Refrigerant Practices!
Trane believes that responsible refrigerant practices are important to the environment, our
customers, and the air conditioning industry. All technicians who handle refrigerants must be
certified. The Federal Clean Air Act (Section 608) sets forth the requirements for handling,
reclaiming, recovering and recycling of certain refrigerants and the equipment that is used in these
service procedures. In addition, some states or municipalities may have additional requirements
that must also be adhered to for responsible management of refrigerants. Know the applicable
laws and follow them.
Overview of Manual
Note: One copy of this document ships inside the control panel of each unit and is customer
property. It must be retained by the unit’s maintenance personnel.
This booklet describes proper installation, operation, and maintenance procedures for air cooled
systems. By carefully reviewing the information within this manual and following the instructions,
the risk of improper operation and/or component damage will be minimized.
It is important that periodic maintenance be performed to help assure trouble free operation. A
maintenance schedule is provided at the end of this manual. Should equipment failure occur,
contact a qualified service organization with qualified, experienced HVAC technicians to properly
diagnose and repair this equipment.
ATTENTION: Warnings, Cautions and Notices appear at appropriate sections throughout
this literature. Read these carefully.
WARNING: Indicates a potentially hazardous situation which, if not avoided, could
result in death or serious injury.
CAUTION: Indicates a potentially hazardous situation which, if not avoided, could
result in minor or moderate injury. It could also be used to alert against unsafe practices.
NOTICE:Indicates a situation that could result in equipment or property-damage-only
accidents.

RT-SVX23E-EN 3
Warnings, Cautions and Notices
WARNING
Personal Protective Equipment (PPE) Required!
Installing/servicing this unit could result in exposure to electrical, mechanical and chemical
hazards.
• Before installing/servicing this unit, technicians MUST put on all Personal Protective
Equipment (PPE) recommended for the work being undertaken. ALWAYS refer to appropriate
MSDS sheets and OSHA guidelines for proper PPE.
• When working with or around hazardous chemicals, ALWAYS refer to the appropriate MSDS
sheets and OSHA guidelines for information on allowable personal exposure levels, proper
respiratory protection and handling recommendations.
• If there is a risk of arc or flash, technicians MUST put on all necessary Personal Protective
Equipment (PPE) in accordance with NFPA70E for arc/flash protection PRIOR to servicing the
unit.
Failure to follow recommendations could result in death or serious injury.
WARNING
Contains Refrigerant under Pressure!
System contains oil and refrigerant under high pressure. Recover refrigerant to relieve pressure
before opening the system. See unit nameplate for refrigerant type. Do not use non-approved
refrigerants, refrigerant substitutes, or refrigerant additives. Failure to follow proper procedures
or the use of non-approved refrigerants, refrigerant substitutes, or refrigerant additives could
result in death or serious injury or equipment damage.
WARNING
R-410A Refrigerant under Higher Pressure than R-22!
The units described in this manual use R-410A refrigerant which operate at higher pressures
than R-22 refrigerant. Use ONLY R-410A rated service equipment or components with this unit.
For specific handling concerns with R-410A, please contact your local Trane representative.
Failure to use R-410A rated service equipment or components could result in equipment
exploding under R-410A high pressures which could result in death, serious injury, or equipment
damage.
WARNING
Harmful Ultraviolet (UV) Lights!
Do not field install ultraviolet lights in the manufacturer air handling equipment for the intended
purpose of improving indoor air quality. High intensity C-band ultraviolet light is known to
severely damage polymer (plastic) materials and poses a personal safety risk to anyone exposed
to the light without proper personal protective equipment (can cause damage to eyes and skin).
Polymer materials commonly found in HVAC equipment that may be susceptible include
insulation on electrical wiring, fan belts, thermal insulation, various fasteners and bushings.
Degradation of these materials could result in serious damage to the equipment. Failure to
follow this recommendation could result in death or serious injury and equipment damage. The
manufacturer accepts no responsibility for the performance or operation of our air handling
equipment in which ultraviolet devices were installed outside of the manufacturer’s factory.
NOTICE
Roof Damage!
System contains oil and refrigerant under high pressure. Roofs should be protected from
exposure to oils and refrigerant in the system. If rooftop is not protected damage to the roof may
occur.

4RT-SVX23E-EN
Table of Contents
Overview of Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Model Number Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Unit Nameplate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Compressor Nameplate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Unit Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Economizer Control Actuator (Optional) ReliaTel™ Control . . . . . . . . . . . 8
RTCI -- ReliaTel™ Trane Communication Interface (Optional) . . . . . . . . . 8
RLCI - ReliaTel™ LonTalk Communication Interface (Optional) . . . . . . . . 8
RTOM – ReliaTel™ Options Module (Optional) . . . . . . . . . . . . . . . . . . . . . 9
System Input Devices & Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Pre-Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Unit Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Unit Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Unit Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Foundation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Ductwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Roof Curb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Rigging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Factory Installed Economizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Temperature Limit Switch Usage for Electric Heat Units . . . . . . . . . . . . 30
Horizontal Discharge Conversion WSC036E, WSC048E . . . . . . . . . . . . . 30
Horizontal Discharge Conversion WSC060-120E . . . . . . . . . . . . . . . . . . . 31
TCO-A Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Return Air Smoke Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Main Electrical Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Electric Heat Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Low Voltage Wiring (AC & DC) Requirements . . . . . . . . . . . . . . . . . . . . . 36
Condensate Drain Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Filter Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Field Installed Power Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Main Unit Power Standard Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Main Unit Power Optional TBUE Wiring (Through the Base Electrical Op-
tion) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Field Installed Control Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Smoke Detector - (ReliaTel™ only) Customer Low Voltage Wiring- . . . . 44
Pre-Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Space Temperature Averaging (ReliaTel™ only) . . . . . . . . . . . . . . . . . . . 45
Voltage Imbalance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Electrical Phasing (Three Phase Motors) . . . . . . . . . . . . . . . . . . . . . . . . . . 48

RT-SVX23E-EN 5
Table of Contents
Compressor Crankcase Heaters (Optional on WSC036E*, WSC048E1, and
& WSC060E1 - Standard on remaining units) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Test Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
ReliaTel Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Verifying Proper Air Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Units with 5-Tap Direct Drive Indoor Fan . . . . . . . . . . . . . . . . . . . . . . . . . 51
Units with Belt Drive Indoor Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Units with Direct Drive Indoor Fan with MMC . . . . . . . . . . . . . . . . . . . . . 53
Return Air Smoke Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Economizer Start-Up ReliaTel Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Compressor Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Heating Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Final System Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Fan Belt Adjustment - Belt Drive Units . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Monthly Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Return Air Smoke Detector Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . 58
Cooling Season . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Heating Season . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Coil Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Final Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Trouble Shooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Method 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Method 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Resetting Cooling and Heating Lockouts . . . . . . . . . . . . . . . . . . . . . . . . . 64
Zone Temperature Sensor (ZTS) Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Programmable & Digital Zone Sensor Test . . . . . . . . . . . . . . . . . . . . . . . 66
Unit Economizer Control (ECA) Troubleshooting ReliaTel Control . . . . . 67
Troubleshooting procedures for Direct Drive Plenum Fan . . . . . . . . . . . 68
Wiring Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Limited Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Heat Pump WCC, WCD, WCH, WCM and WSC (Parts Only) . . . . . . . . . . 70
Heat Pump WCZ, WCY, WCX, WCC, WCD, WCH, WCM, WCP and WSC
(Parts Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

6RT-SVX23E-EN
Model Number Descriptions
Digit 1 - Unit Type
W Packaged Heat Pump3
Digit 2 - Efficiency
S Standard Efficiency
Digit 3 - Airflow
C Convertible
Digit 4,5,6 - Nominal Gross
Cooling Capacity (MBh)
036 3 Tons
048 4 Tons
060 5 Tons
072 6 Ton
090 7½ Ton, Single Compressor
120 10 Ton
Digit 7 - Major Design Sequence
E R-410A Refrigerant
Digit 8 - Voltage Selection
1 208/230/60/1
3 208-230/60/3
4 460/60/3
W 575/60/3
Digit 9 - Unit Controls
R ReliaTel™ Microprocessor
Digit 10 - Heating Capacity
Digit 11 - Minor Design Sequence
A First Sequence
Digit 12,13 - Service Sequence
** Factory Assigned
0=No Electric Heat F=14 kW (1 phase)1
A=5 kW (1 phase)1G=18 kW (1&3 phase)
B=6 kW (3 phase) J=23 kW (3 phase)
C=9 kW (3 phase) K= 27 kW (3 phase)
D=10 kW (1 phase)1N = 36 kW (3 phase)
E=12 kW (3 phase) P = 54 kW (3 phase)
Digit 14 - Fresh Air Selection
0NoFreshAir
A Manual Outside Air Damper 0-50%2
B Motorized Outside Air Damper
0-50%
C Economizer, Dry Bulb 0-100%
without Barometric Relief5
D Economizer, Dry Bulb 0-100%
with Barometric Relief5
E Economizer, Reference Enthalpy
0-100% without Barometric Relief5
F Economizer, Reference Enthalpy
0-100% with Barometric Relief5
G Economizer, Comparative
Enthalpy 0-100% without
Barometric Relief5
H Economizer, Comparative
Enthalpy 0-100% with Barometric
Relief5
Digit 15 - Supply Fan/Drive Type/
Motor
0 Standard Drive4
1 Oversized Motor
2 Optional Belt Drive Motor
Digit 16 - Hinged Service Access/
Filters
0 Standard Panels/Standard Filters
A Hinged Access Panels/Standard
Filters
B Standard Panels/2” MERV 7 Filters
C Hinged Access Panels/2” MERV 7
Filters
D Standard Panels/2” MERV 13 Filters
E Hinged Access Panels/2” MERV 13
Filters
Digit 17 - Condenser Coil
Protection
0 Standard Coil
1 Standard Coil with Hail Guard
2 Black Epoxy Pre-Coated Condenser
Coil
3 Black Epoxy Pre-Coated
Condenser Coil with Hail Guard
4 CompleteCoat™ Condenser Coil
5 CompleteCoat™ Condenser Coil
with Hail Guard
Digit 18 - Through the Base
Provisions
0 No Through the Base Provisions
A Through the Base Electric6
Digit 19 - Disconnect/Circuit
Breaker (three-phase only)
0 No Disconnect/No Circuit Breaker
1 Unit Mounted Non-Fused
Disconnect6
2 Unit Mounted Circuit Breaker6
Digit 20 - Convenience Outlet
0 No Convenience Outlet
A Unpowered Convenience Outlet
B Powered Convenience Outlet
(three-phase only)7
Digit 21 - Communications
Options
0 No Communications Interface
1TCI
2LCI
Digit 22 - Refrigeration System
Option
0 Standard Refrigeration System8
Digit 23 - Refrigeration Controls
0 No Refrigeration Control3
1Frostat
2CrankcaseHeater
11
3 Frostat and Crankcase Heater11
Digit 24 - Smoke Detector
0 No Smoke Detector
A Return Air Smoke Detector9
B Supply Air Smoke Detector
C Supply and Return Air Smoke
Detectors9
Digit 25 - Monitoring Controls
0 No Monitoring Control
1 Clogged Filter Switch
2 Fan Failure Switch
3 Discharge Air Sensing Tube
4 Clogged Filter Switch and Fan
Fail Switch
5 Clogged Filter Switch and Discharge
Air Sensing Tube
6 Fan Fail Switch and Discharge Air
Sensing Tube
7 Clogged Filter and Fan Fail Switches
and Discharge Air Sensing Tube

RT-SVX23E-EN 7
Model Number Descriptions
Model Number Notes
1. Available on 3-5 Ton Models.
2. Manual outside air damper will
ship factory supplied within the
unit, but must be field installed.
3. High pressure control is standard
on all units.
4. Multispeed direct drive standard
on single-phase products. Belt
drive standard on three-phase 3-
7½ ton. Variable speed direct drive
standard on 10 ton.
5. Economizer with Barometric
Relief is for downflow configured
units only. Order Economizer
without Barometric Relief for
horizontal configuration.
Barometric Relief for horizontal
configured units must be ordered
as field installed accessory.
6. Through the base electric required
when ordering disconnect/circuit
breaker options.
7. Requires use of Disconnect or
Circuit Breaker.
8. Standard metering devices are
TXVs.
9. The return air smoke detector may
not fit up or work properly on the
units when used in conjunction
with 3rd party accessories such as
bolt on heat wheels, economizers
and power exhaust. Do not order
the return air smoke detectors
when using this type of accessory.
10. Requires hinged access panels.
11. Crankcase heaters are only
available as option on WSC036E,
WSC048E1, & WSC060E1. CCH are
standard on all other units.

8RT-SVX23E-EN
General Information
Unit Nameplate
A Mylar unit nameplate is located on the unit’s corner support next to the filter access panel. It
includes the unit model number, serial number, electrical characteristics, refrigerant charge, as well
as other pertinent unit data.
Compressor Nameplate
The nameplate for the compressors are located on the side of the compressor.
Unit Description
Before shipment, each unit is leak tested, dehydrated, charged with refrigerant and compressor oil,
and run tested for proper control operation.
The condenser coils are aluminum fin, mechanically bonded to copper tubing.
Direct-drive, vertical discharge condenser fans are provided with built-in thermal overload
protection.
The ReliaTel™ Control Module is a microelectronic control system that is referred to as
“Refrigeration Module” (RTRM). The acronym RTRM is used extensively throughout this
document when referring to the control system network.
These modules through Proportional/Integral control algorithms perform specific unit functions
that governs unit operation in response to; zone temperature, supply air temperature, and/or
humidity conditions depending on the application. The stages of capacity control for these units
is achieved by starting and stopping the compressors.
The RTRM is mounted in the control panel and is factory wired to the respective internal
components. The RTRM receives and interpret information from other unit modules, sensors,
remote panels, and customer binary contacts to satisfy the applicable request for cooling.
Economizer Control Actuator (Optional) ReliaTel™ Control
The ECA monitors the mixed air temperature, return air temperature, minimum position setpoint
(local or remote), power exhaust setpoint, CO2 setpoint, CO2, and ambient dry bulb/enthalpy
sensor or comparative humidity (return air humidity against ambient humidity) sensors, if
selected, to control dampers to an accuracy of +/- 5% of stroke. The actuator is spring returned to
the closed position any time that power is lost to the unit. It is capable of delivering up to 25 inch
pounds of torque and is powered by 24 VAC.
RTCI -- ReliaTel™ Trane Communication Interface (Optional)
This module is used when the application calls for an ICSTM building management type control
system. It allows the control and monitoring of the system through an ICS panel. The module can
be ordered from the factory or ordered as a kit to be field installed. Follow the installation
instruction that ships with each kit when field installation is necessary.
RLCI - ReliaTel™ LonTalk Communication Interface (Optional)
This module is used when the application calls for an ICSTM building management type control
system that is LonTalk. It allows the control and monitoring of the system through an ICS panel.
The module can be ordered from the factory or ordered as a kit to be field installed. Follow the
installation instruction that ships with each kit when field installation is necessary.

RT-SVX23E-EN 9
General Information
RTOM – ReliaTel™ Options Module (Optional)
The RTOM monitors the supply fan proving, clogged filter, supply air temperature, exhaust fan
setpoint, supply air tempering, Frostat™ and smoke detector. Refer to system input devices and
functions for operation.
System Input Devices & Functions
The RTRM must have a zone sensor or thermostat input in order to operate the rooftop unit. The
flexibility of having several mode capabilities depends upon the type of zone sensor thermostat
selected to interface with the RTRM.
The descriptions of the following basic Input Devices used within the RTRM network are to acquaint
the operator with their function as they interface with the various modules. Refer to the unit’s
electrical schematic for the specific module connections.
The following controls are available from the factory for field installation.
Supply Fan Failure Input (Optional)
The Fan Failure Switch can be connected to sense indoor fan operation:
FFS (Fan Failure Switch) If air flow through the unit is not proven by the differential pressure switch
connected to the RTRM (factory set point 0.07 “w.c.) within 40 seconds nominally, the RTRM will
shut off all mechanical operations, lock the system out, send a diagnostic to ICS, and the SERVICE
output will flash. The system will remain locked out until a reset is initiated either manually or
through ICS.
Clogged Filter Switch (Optional)
The unit mounted clogged filter switch monitors the pressure differential across the return air
filters. It is mounted in the filter section and is connected to the RTOM. A diagnostic SERVICE signal
is sent to the remote panel if the pressure differential across the filters is at least 0.5" w.c. The
contacts will automatically open when the pressure differential across the filters decreases to
approximately 0.4" w.c. The clogged filter output is energized when the supply fan is operating and
the clogged filter switch has been closed for at least 2 minutes. The system will continue to operate
regardless of the status of the filter switch.
Note: On units equipped with factory installed MERV 13 filters, a clogged filter switch with
different pressure settings will be installed. This switch will close when the differential
pressure is approximately 0.8' w.c. and open when the differential falls to 0.7" w.c.
Compressor Disable (CPR1/2)
This input incorporates the low pressure control (LPC) of each refrigeration circuit and can be
activated by opening a field supplied contact installed on the LTB.
If this circuit is open before the compressor is started, the compressor will not be allowed to
operate. Anytime this circuit is opened for 1 continuous second during compressor operation, the
compressor for that circuit is immediately turned “Off”. The compressor will not be allowed to
restart for a minimum of 3 minutes should the contacts close.
If four consecutive open conditions occur during the first three minutes of operation, the
compressor for that circuit will be locked out, a diagnostic communicated to the remote panel (if
installed), and a manual reset will be required to restart the compressor.
Low Pressure Control
When the LPC is opened for 1 continuous second, the compressor for that circuit is turned off
immediately. The compressor will not be allowed to restart for a minimum of 3 minutes.
If four consecutive open conditions occur during an active call for cooling, the compressor will be
locked out, a diagnostic communicated to ICS™, if applicable, and a manual reset required to

10 RT-SVX23E-EN
General Information
restart the compressor. On dual compressor units only the affected compressor circuit is locked
out.
High Pressure Control
The high pressure controls are wired in series between the compressor outputs on the RTRM and
the compressor contactor coils. If the high pressure control switch opens, the RTRM senses a lack
of current while calling for cooling and locks the compressor out.
If four consecutive open conditions occur during an active call for cooling, the compressor will be
locked out, a diagnostic communicated to ICS™, if applicable, and a manual reset required to
restart the compressor. On dual compressor units only the affected compressor circuit is locked
out.
Power Exhaust Control (Optional)
The power exhaust fan is started whenever the position of the economizer dampers meets or
exceed the power exhaust setpoint when the indoor fan is on.
The setpoint panel is located in the return air section and is factory set at 25%.
Lead/Lag Control (Dual Circuit Only)
Lead/Lag is a selectable input located on the RTRM. The RTRM is configured from the factory with
the Lead/Lag control disabled. To activate the Lead/Lag function, simply cut the wire connected to
J3-8 at the RTRM. When it is activated, each time the designated lead compressor is shut off due
to the load being satisfied, the lead compressor or refrigeration circuit switches. When the RTRM
is powered up, i.e. after a power failure, the control will default to the number one circuit
compressor.
Zone Sensor Module (ZSM) (BAYSENS107*)
This electronic sensor features three system switch settings (Heat, Cool, and Off) and two fan
settings (On and Auto). It is a manual changeover control with single setpoint. (Cooling Setpoint
Only)
Zone Sensor Module (ZSM) (BAYSENS109*)
This electronic sensor features four system switch settings (Heat, Cool, Auto, and Off) and two fan
settings (On and Auto). It is a manual or auto changeover control with dual setpoint capability. It
can be used with a remote zone temperature sensor BAYSENS077*.
Programmable Zone Sensor - BAYSENS119*
This 7 day programmable sensor features 2, 3 or 4 periods for Occupied or Unoccupied
programming per day. If the power is interrupted, the program is retained in permanent memory.
If power is off for an extended period of time, only the clock and day may have to be reset.
The Zone Sensor allows selection of 2, 3 or 4 system modes (Heat, Cool, Auto, and Off), two fan
modes (On and Auto). It has dual temperature selection with programmable start time capability.
The occupied cooling set point ranges between 45 and 98 degrees Fahrenheit. The heating set point
ranges between 43 and 96 degrees Fahrenheit.
A liquid crystal display (LCD) displays zone temperature, temperature set points, day of the week,
time, and operational mode symbols.
The Option Menu is used to enable or disable applicable functions, i.e.; Morning Warm-up,
Economizer minimum position override during unoccupied status, Fahrenheit or Centigrade,
Supply air tempering, Remote zone temperature sensor, 12/24 hour time display, Smart fan, and
Computed recovery.
During an occupied period, an auxiliary relay rated for 1.25 amps @ 30 volts AC with one set of
single pole double throw contacts is activated. Electronic Timeclock (BAYCLCK001A).