American Standard YSC036A Installation and operating instructions

Installation
Operation and
Maintenance
June 2008 RT-SVX21F-EN
Model Numbers:
YSC036A - YSC120A YHC036E - YHC060E
YHC033A - YHC120A YSC072 - YSC120E
YSC036E - YSC060E
Packaged Gas/Electric
3 - 10 Ton

Preface and Warnings and Cautions
© 2007 American Standard Inc. All rights reserved RT-SVX21F-EN
Hazard Identification
Warnings and Cautions appear at
appropriate sections throughout this
manual. 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, may
result in minor or moderate injury. It
may also be used to alert against
unsafe practices.
CAUTION
Indicates a situation that may result
in equipment or property-damage-
only accidents.
Unit Inspection
As soon as the unit arrives at the job
site
• Verify that the nameplate data
matches the data on the sales
order and bill of lading (including
electrical data).
• Verify that the power supply
complies with the unit
nameplate specifications.
• Visually inspect the exterior of
the unit, including the roof, for
signs of shipping damage.
If the job site inspection of the unit
reveals damage or material
shortages, file a claim with the carrier
immediately. Specify the type and
extent of the damage on the “bill of
lading” before signing.
• Visually inspect the internal
components for shipping
damage as soon as possible after
delivery and before it is stored.
Do not walk on the sheet metal
base pans.
• If concealed damage is
discovered, notify the carrier’s
terminal of damage immediately
by phone and by mail. Concealed
damage must be reported within
15 days.
• Request an immediate joint
inspection of the damage by the
carrier and the consignee. Do not
remove damaged material from
the receiving location. Take
photos of the damage, if
possible. The owner must
provide reasonable evidence that
the damage did not occur after
delivery.
• Notify the appropriate sales
representative before installing
or repairing a damaged unit.
Storage
Take precautions to prevent
condensate from forming inside the
unit’s electrical compartments and
motors if:
1. the unit is stored before it is
installed; or,
2. the unit is set on the roof curb,
and temporary heat is provided
in the building. Isolate all side
panel service entrances and base
pan openings (e.g., conduit
holes, S/A and R/A openings, and
flue openings) from the ambient
air until the unit is ready for start-
up.
Note: Do not use the unit’s heater
for temporary heat without
first completing the start-up
procedure detailed under
“Starting the Unit”.
The manufacturer will not assume
any responsibility for equipment
damage resulting from condensate
accumulation on the unit’s electrical
and/or mechanical components.
Model Number Description
All products are identified by a
multiple-character model number
that precisely identifies a particular
type of unit. Its use will enable the
owner/operator, installing
contractors, and service engineers to
define the operation, specific
components, and other options for
any specific unit.
When ordering replacement parts or
requesting service, be sure to refer to
the specific model number and serial
number printed on the unit
nameplate.
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.
WARNING
Contains Refrigerant!
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
Hazardous Voltage w/
Capacitors!
Disconnect all electric power,
including remote disconnects and
discharge all motor start/run
capacitors before servicing. Follow
proper lockout/tagout procedures to
ensure the power cannot be
inadvertently energized. Verify with
an appropriate voltmeter that all
capacitors have discharged. Failure
to disconnect power and discharge

RT-SVX21F-EN 3
Preface and Warnings and Cautions
capacitors before servicing could
result in death or serious injury.
WARNING
R410a Refrigerant!
R-410A refrigerant systems operate
at higher pressures than standard R-
22 systems. Do not use R-22 service
equipment or components on R-
410A refrigerant equipment. If
service equipment is not rated for R-
410A refrigerant, equipment damage
or personal injury may result.
CAUTION
Equipment Damage From
Ultraviolet (UV) Lights!
The manufacturer does not
recommend field installation of
ultraviolet lights in its 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. 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 can
result in serious damage to the
equipment.
The manufacturer accepts no
responsibility for the performance or
operation of our equipment in which
ultraviolet devices were installed
outside of the manufacturer’s factory
or its approved suppliers.
CAUTION
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-SVX21F-EN
Hazard Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Unit Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Overview of Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Model Number Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Unit Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Unit Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Pre-Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Foundation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Roof Curb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
General Unit Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Horizontal Discharge Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
TCO-1 Instructions: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Horizontal Discharge Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Return Air Smoke Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Through the Base Gas Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Requirements for Gas Heat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Filter Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Field Installed Power Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Main Unit Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Main Unit Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Controls using DC Analog Input/Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Smoke Detector
Customer Low Voltage Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Space Temperature Averaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Voltage Imbalance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Electrical Phasing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Pre-Start. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Test Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Verifying Proper Air Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
ReliaTel Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Electro Mechanical Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Verifying Proper Air Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Verifying Proper Air Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Return Air Smoke Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Economizer Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Compressor Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Final System Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Fan Belt Adjustment - Belt Drive Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Monthly Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Contents

RT-SVX21F-EN 5
Contents
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Annual Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Final Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
ReliaTel Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
System Status Checkout Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Trouble Shooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Resetting Cooling and Ignition Lockouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Zone Temperature Sensor (ZTS) Service Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Clogged Filter Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Fan Failure Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Zone Temperature Sensor (ZTS) Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Unit Economizer Control (ECA) Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Resetting Cooling and Ignition Lockouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Unit Economizer Control (ECA) Test Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Combination Gas Electric Air Conditioner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Limited Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Combination Gas Electric Air Conditioner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

6RT-SVX21F-EN
DIGIT 1 — UNIT TYPE
T DX Cooling
Y DX Cooling, Gas Heat
W Packaged Heat Pump2
DIGIT 2 — EFFICIENCY
S Standard Efficiency
H High Efficiency
DIGIT 3 — AIRFLOW
C Convertible
DIGIT 4,5,6 — NOMINAL GROSS
COOLING CAPACITY (MBh)
033 3 Ton
036 3 Tons
043 4 Ton
048 4 Tons
060 5 Tons
063 5 Ton
072 6 1/4 Ton
090 7 1/2 Ton (Single Compressor)
092 7 1/2 Ton (Dual Compressor)
102 8 1/2 Ton
120 10 Ton
DIGIT 7 — MAJOR DESIGN
SEQUENCE
A R-22 Refrigerant
E R-410A Refrigerant
DIGIT 8 — VOLTAGE SELECTION
1 208-230/60/1
3 208-230/60/3
4 460/60/3
D 380-415/50/3
K 380/60/3
T200/50/3
W = 575/60/3DIGIT 9 — UNIT
CONTROLS
E Electromechanical1
R ReliaTel™ Microprocessor
DIGIT 10 — HEATING CAPACITY
Note: Applicable to Digit 1, Y
models only.
YHC033A3RBA**C000A10001A1
1 2 34567 8 9 101112,13141516171819202122232425
0=No Electric Heat E=12 kW (3 phase)
A=5 kW (1 phase)2F=14 kW (1 phase)2
B=6 kW (3 phase) G=18 kW (1&3 phase)
D=10 kW (1 phase)2J=23 kW (3 phase)
LLow
MMedium
HHigh
X Low, Stainless Steel Heat
Exchanger
Y Medium, Stainless Steel Heat
Exchanger
Z High, Stainless Steel Heat
Exchanger
DIGIT 11 — MINOR DESIGN
SEQUENCE
A First Sequence
DIGIT 12,13 — SERVICE SEQUENCE
** Factory Assigned
DIGIT 14 — FRESH AIR SELECTION
0NoFreshAir
A Manual Outside Air Damper
0-50%5
B Motorized Outside Air Damper
0-50%
C Economizer, Dry Bulb 0-100%
without Barometric Relief8
D Economizer, Dry Bulb 0-100%
with Barometric Relief8
E Economizer, Reference Enthalpy
0-100% without Barometric
Relief4,8
F Economizer, Reference Enthalpy
0-100% with Barometric Relief4,8
G Economizer, Comparative
Enthalpy 0-100% without
Barometric Relief4,8
H Economizer, Comparative
Enthalpy 0-100% with Barometric
Relief4,8
DIGIT 15 - SUPPLY FAN/DRIVE
TYPE/MOTOR
0StandardDrive
7
2) Optional Belt Drive Motor20
DIGIT 16 - HINGED SERVICE
ACCESS/FILTERS
0 Standard Panels/Standard Filters
A Hinged Access Panels/Standard
Filters
B Standard Panels/2” Pleated
Filters
C Hinged Access Panels/2” Pleated
Filters
DIGIT 17 - CONDENSER COIL
PROTECTION
0StandardCoil
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
Note: (Applicable to Digit 1, T or Y
models)
0 No Through the Base Provisions
A Through the Base Electric9
Note: (Applicable to Digit 1, Y
models only)
B Through the Base Gas Piping
C Through the Base Electric and
Gas Piping17
DIGIT 19 - DISCONNECT/CIRCUIT
BREAKER/PHASE MONITOR
(THREE- PHASE ONLY)
0 No Disconnect / No Circuit
Breaker / No Phase Monitor 21
1 No Change
2NoChange
3PhaseMonitor
22
4 Phase Monitor & Non-Fused
Disconnect Switch22)
5 Phase Monitor & Circuit Breaker
22
DIGIT 20 - CONVENIENCE OUTLET
0 No Convenience Outlet
A Unpowered Convenience Outlet
B Powered Convenience Outlet
(three-phase only)10
DIGIT 21 - COMMUNICATIONS
OPTIONS4
0 No Communications Interface
1 Trane Communications Interface
2 LonTalk® Communications
Interface
3 Novar 2024 Controls1
4 Novar 3051 Controls1without
Zone Sensor23
Model Number Description

RT-SVX21F-EN 7
Model Number Description
DIGIT 22 - REFRIGERATION SYSTEM
OPTION
0 Standard Refrigeration System11
A Expansion Valve (standard for 3-
10 Ton R410a Units)
B Standard Refrigeration System
(not yet available for 3-10 Ton
R410a Units)
DIGIT 23 - REFRIGERATION
CONTROLS
Note: Applicable to Digit 7 = A
0 No Refrigeration Control6
2Frostat
12
3 Crankcase Heater3
6Frostat
12 and Crankcase Heater3
Note: Applicable to Digit 7 = E
0 No Refrigeration Control6
1Frostat
12
2 Crankcase Heater3
3Frostat
12 and Crankcase Heater3
DIGIT 24 - SMOKE DETECTOR4,18
0 No Smoke Detector
A Return Air Smoke Detector13,14
B Supply Air Smoke Detector
C Supply and Return Air Smoke
Detectors13,14
DIGIT 25 - MONITORING
CONTROLS4
0 No Monitoring Control15
1 Clogged Filter Switch15
2 Fan Failure Switch15
3 Discharge Air Sensing Tube15
4 Clogged Filter Switch and Fan
Fail Switch15
5 Clogged Filter Switch and
Discharge Air Sensing Tube15
6 Fan Fail Switch and Discharge Air
Sensing Tube15
7 Clogged Filter and Fan Fail
Switches and Discharge Air
Sensing Tube15
8 Novar Return Air Sensor16
9 Novar Zone Sensor23
Model Number Notes
1. Not available with Heat Pumps.
2. Available for R-410A units only.
3. Standard on all 15 SEER and 4-5
Tons Heat Pump R-22 units.
4. Not available with
electromechanical controls.
5. Manual outside air damper will
ship factory supplied within the
unit, but must be field installed.
6. High pressure control is standard
on all units.
7. Multispeed direct drive standard
on single-phase and 15 SEER
products. Belt drive standard on
three-phase 13 SEER and 6-10
ton R410a products.
8. 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.
9. Through the base electric
required when ordering
disconnect/circuit breaker
options.
10. Requires use of Disconnect or
Circuit Breaker.
11. Standard metering devices are
TXVs.
12. Frostat cannot be field installed
in electro-mechanical units.
13. The return air smoke detector
may not fit up or work properly
on the Precedent 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.
14. Return Air Smoke Detector
cannot be ordered with Novar
Controls.
15. These options are standard
when ordering Novar Controls.
16. This option is used when
ordering Novar Controls.
17. Includes gas piping and shutoff
(field assembly required).
18. Not available with high
temperature stat accessory.
19. Requires hinged access panels.
20. Belt Drive Optional on three-
phase 15 SEER, R-410A units.
21. Phase Reversal protection is
standard on 3 - 5 ton units with
Direct Drive and 3-phase power
22. Available on Belt Drive (3-10
tons)
23. Novar Sensor utilized with digit
21 = (4) Novar 3051 Cotrols
without Zone Sensor

8RT-SVX21F-EN
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.
There are two control systems
offered for these units. The electro
mechanical control option uses a
thermostat to perform unit functions.
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 are
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 interprets
information from other unit
modules, sensors, remote panels,
and customer binary contacts to
satisfy the applicable request for
cooling.
Economizer Control Actuator
(Optional)
Electro Mechanical Control
The ECA monitors the mixed air
temperature, ambient dry bulb
temperature and local minimum
position setpoint 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.
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.
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 unit. The flexibility of
having several mode capabilities
depends upon the type of zone
sensor or 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 RTOM (factory set
point 0.07 “ w.c.) within 40 seconds
General Information

RT-SVX21F-EN 9
General Information
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.
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
ReliaTel 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
restart the compressor. On dual
compressor units only the affected
compressor circuit is locked out.
Electromechanical Control
When the LPC is opened, the
compressor for that circuit is turned
off immediately. The compressor will
restart when the LPC closes.
High Pressure Control
(Optional — except on
R-410A units)
ReliaTel 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.
Electromechanical Control
When the HPC is opened, the
compressor for that circuit is turned
off immediately. The compressor will
restart when the HPC closes.
Power Exhaust Control
(Optional)
ReliaTel Control
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.
With the optional ventilation override
accessory, the power exhaust fan is
independent of the indoor fan.
The setpoint panel is located in the
return air section and is factory set at
25%.
Electromechanical Control
The power exhaust fan is started
whenever the indoor fan is on and
the adjustable damper limit switch
DLS is closed.
Lead/Lag Control
(Dual Circuit Only)
ReliaTel Control 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)
(BAYSENS006B)
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)

10 RT-SVX21F-EN
General Information
Zone Sensor Module (ZSM)
(BAYSENS008B)
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 BAYSENS017B.
Zone Sensor (BAYSENS010B)
This electronic sensor features four
system switch settings (Heat, Cool,
Auto, and Off) and two fan settings
(On and Auto) with four system
status LED’s. It is a manual or auto
changeover control with dual
setpoint capability. It can be used
with a remote zone temperature
sensor BAYSENS017B.
Wall Mounted Relative
Humidity Sensor
(BAYSENS036A)
Field installed, wall mounted
humidity sensor is used to control
activation of the hot gas reheat
dehumidification option. Humidity
set points can be selected for relative
humidity levels between 40% and
60% by adjusting the DEHUMID
setting on the ReliaTel Options
Module. See Figure 29 on page 28.
Duct Mounted Relative
Humidity Sensor
(BAYSENS037A)
Field installed, duct mounted
humidity sensor is used to control
activation of the hot gas reheat
dehumidification option. Humidity
set points can be selected for relative
humidity levels between 40% and
60% by adjusting the DEHUMID
setting on the ReliaTel Options
Module. See Figure 29 on page 28.
Programmable Zone Sensor -
(BAYSENS019B)
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.
Status Inputs (4 Wires
Optional)
The ZSM can be wired to receive four
(4) operating status signals from the
RTRM (HEAT, COOL, SYSTEM “ON”,
SER-VICE).
Four (4) wires from the RTRM should
be connected to the appropriate
terminals (7, 8, 9 & 10) on the ZSM.
Remote Zone Sensor
(BAYSENS013B)
This electronic sensor features
remote zone sensing and timed
override with override cancellation. It
is used with a Trane Integrated
ComfortTM building management
system.
Remote Zone Sensor
(BAYSENS014B)
This electronic sensor features single
setpoint capability and timed
override with override cancellation. It
is used with a Trane Integrated
ComfortTM building management
system.
Remote Zone Sensor
(BAYSENS016A)
This bullet type temperature sensor
can be used for; outside air (ambient)
sensing, return air temperature
sensing, supply air temperature
sensing, remote temperature sensing
(uncovered. Wiring procedures vary
according to the particular
application and equipment involved.
Refer to the unit’s wiring diagrams
for proper connections.
Remote Zone Sensor
(BAYSENS017B)
This electronic sensor can be used
with BAYSENS006B, 008B, 010B,
019B Remote Panels. When this
sensor is wired to a BAYSENS019B
Remote Panel, wiring must be 18
AWG Shielded Twisted Pair (Belden
8760 or equivalent). Refer to The
specific Remote Panel for wiring
details.
Electro Mechanical Control
The unit must have a Thermostat to
operate.
• BAYSTAT036A
– Single Stage - 1 Heat/1 Cool
• BAYSTAT037A
– Multi Stage - 2 Heat/2 Cool -
Can be Used for Economizer
Operation
• BAYSENS025A
– Remote sensor for
BAYSTAT036A and
BAYSTAT037A
High Temperature Sensor
(BAYFRST001A)
This sensor connects to the RTRM
Emergency Stop Input on the LTB
and provides high limit “shutdown”
of the unit. The sensor is used to
detect high temperatures due to fire
in the air conditioning or ventilation
ducts. The sensor is designed to
mount directly to the sheet metal
duct. Each kit contains two sensors.
The return air duct sensor
(X1310004001) is set to open at 135 F.
The supply air duct sensor
(X1310004002) is set to open at 240 F.
The control can be reset after the
temperature has been lowered
approximately 25 F below the cutout
setpoint.

RT-SVX21F-EN 11
General Information
Evaporator Frost Control
(ReliaTel™ Option)
This input incorporates the Frostat™
control (FOS) mounted in the indoor
coil circuit and can be activated by
closing a field supplied contact
installed in parallel with the FOS.
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 FOS close.
(Electro Mechanical Option)
This input incorporates the Frostat™
control (FOS) mounted in the indoor
coil circuit and can be activated by
opening a field supplied contact
installed in series with the FOS.
If this circuit is open before the
compressor is started, the
compressor will not be allowed to
operate. Anytime this circuit is
opened during compressor
operation, the compressor for that
circuit is immediately turned “Off”.
The compressor will restart when the
FOS closes.
Smoke Detector Sensor
(Optional)
This sensor is only applicable on
units equipped with a RTOM. It
provides high limit “shutdown” of
the unit and requires a manual reset.
The sensor is used to detect smoke
due to fire in the air conditioning or
ventilation ducts.
Note: The supply and return air
smoke detectors are
designed to shut off the unit if
smoke is sensed in the supply
air stream or return air
stream. This function is
performed by sampling the
airflow entering the unit at
the return air opening. Follow
the instructions provided
below to assure that the
airflow through the unit is
sufficient for adequate
sampling. Failure to follow
these instructions will
prevent the smoke detectors
from performing it's design
function.
Note: Airflow through the unit is
affected by the amount of dirt
and debris accumulated on
the indoor coil and filters. To
insure that airflow through
the unit is adequate for
proper sampling by the
return air smoke detector,
complete adherence to the
maintenance procedures,
including recommended
intervals between filter
changes, and coil cleaning is
required.
Note: Periodic checks and
maintenance procedures
must be performed on the
smoke detector to insure that
it will function properly. For
detailed instructions
concerning these checks and
procedures, refer to the
appropriate section(s) of the
smoke detector Installation
and Maintenance Instructions
provided with the literature
package for this unit.
In order for the supply air smoke
detector or return air smoke detector
to properly sense smoke in the
supply air stream or return air
stream, the air velocity entering the
smoke detector unit must be
between 500 and 4000 feet per
minute. Equipment covered in this
manual will develop an airflow
velocity that falls within these limits
over the entire airflow range
specified in the evaporator fan
performance tables.
There are certain models, however, if
operated at low airflow, will not
develop an airflow velocity that falls
within the required 500 to 4000 feet
per minute range. For these models,
the design airflow shall be greater
than or equal to 1000 feet per minute
MINIMUM.
Phase Monitor (Optional)
ReliaTel Control Only
This sensor monitors voltage
between the 3 conductors of the 3
phase power supply. Two LED lights
are provided. The green light
indicates that a balanced 3 phase
supply circuit is properly connected.
The red light indicates that unit
operation has been prevented. There
are two conditions that will prevent
unit operation.The power supply
circuit is not balanced with the
proper phase sequence of L1, L2, L3
for the 3 conductors of a 3 phase
circuit. The line to line voltage is not
between 180 volts and 633 volts

12 RT-SVX21F-EN
Unit Clearances
Figure 1 illustrates the minimum
operating and service clearances for
either a single or multiple unit
installation. These clearances are the
minimum distances necessary to
assure adequate serviceability,
cataloged unit capacity, and peak
operating efficiency.
Figure 1. Typical Installation Clearances for Single & Multiple Unit Applications
033A THROUGH 063A UNITS033A THROUGH 063A UNITS
036A THROUGH 060A UNITS036A THROUGH 060A UNITS
YHC036E UNITSYHC036E UNITS
072A THROUGH 120A UNITS072A THROUGH 120A UNITS
YHC048E AND YHC060E UNITSYHC048E AND YHC060E UNITS
YSC072E, YSC092E, YSC102E,YSC072E, YSC092E, YSC102E,
YSC120E UNITSYSC120E UNITS
Providing less than the
recommended clearances may result
in condenser coil starvation, “short-
circuiting” of exhaust and
economizer airflows, or recirculation
of hot condenser air.
Unit Dimensions

RT-SVX21F-EN 13
Unit Dimensions
Figure 2. Unit Dimensional Data YHC033A, Y(H/S)C036A, YHC043A, Y(H/S)C048A — Low and Medium Heat
YSC060A — Low and Medium Heat
Figure 3. YHC033A, Y(H/S)C036A, YHC043A,Y(H/S)C048A — High Heat YSC060A — High Heat YHC060A, YHC063A
— Low, Medium, and High Heat YSC036E, YSC048E, YSC060E, YHC036E
17751775
17751775

14 RT-SVX21F-EN
Unit Dimensions
Figure 4. Unit Dimensional Data Y(H/S)C072A, YSC090A, YSC092A, YHC048E, YHC060E, YSC072E
Figure 5. Dimensional Data YHC092A, Y(H/S)102A, Y(H/S)C120A, YSC092E, YSC102E, YSC120E

RT-SVX21F-EN 15
WARNING
Fiberglass Wool !
Product contains fiberglass wool.
Disturbing the insulation in this
product during installation,
maintenance or repair will expose
you to airborne particles of glass
wool fibers and ceramic fibers
known to the state of California to
cause cancer through inhalation.
Glass wool fibers may also cause
respiratory, skin or eye irritation.
Precautionary Measures
• Avoid breathing fiberglass dust.
• Use a NIOSH approved dust/
mist respirator.
• Avoid contact with the skin or
eyes. Wear long-sleeved, loose-
fitting clothing, gloves, and eye
protection.
• Wash clothes separately from
other clothing: rinse washer
thoroughly.
• Operations such as sawing,
blowing, tear-out, and spraying
may generate fiber
concentrations requiring
additional respiratory
protection. Use the appropriate
NIOSH approved respiration in
these situations.
First Aid Measures
Eye Contact - Flush eyes with water
to remove dust. If symptoms persist,
seek medical attention.
Skin Contact - Wash affected areas
gently with soap and warm water
after handling.
Pre-Installation

16 RT-SVX21F-EN
WARNING
Heavy Objects!
Do not use cables (chains or slings)
except as shown. Each of the cables
(chains or slings) used to lift the unit
must be capable of supporting the
entire weight of the unit. Lifting
cables (chains or slings) may not be
of the same length. Adjust as
necessary for even unit lift. Other
lifting arrangements may cause
equipment or property-only damage.
Failure to properly lift unit could
result in death or serious injury .
WARNING
Improper Unit Lift!
Test lift unit approximately 24 inches
to verify proper center of gravity lift
point. To avoid dropping of unit,
reposition lifting point if unit is not
level. Failure to properly lift unit
could result in death or serious
injury or possible equipment or
property-only damage.
Figure 6. Corner weights
Table 1. Typical unit weights and point
loading data
Net
Weight
(lbs)
Corner Wt. (lbs) Center of Gravity (In.)
Unit Model A B C D Length Width
YSC036A1*(L,M,X,Y) 453 143 116 90 104 32 19
YSC036A1*(H,Z) 480 151 124 96 109 32 19
YSC036A(3,4,W)*(L,M,X,Y) 453 143 116 90 104 32 19
YSC036A(3,4,W)*(H,Z) 480 151 124 96 109 32 19
YSC036E(1,3,4,W) 532 165 137 95 134 31 19
YSC048A1*(L,M,X,Y) 478 151 122 102 103 33 19
YSC048A1*(H,Z) 505 159 130 108 109 33 19
YSC048A(3,4,W)*(L,M,X,Y) 465 146 121 101 97 33 19
YSC048A(3,4,W)*(H,Z) 492 154 129 107 103 33 19
YSC048E(1,3,4,W) 563 175 145 101 142 31 19
YSC060A1*(L,M,X,Y) 494 160 127 99 108 32 18
YSC060A1*(H,Z) 522 169 134 105 114 32 18
YSC060A(3,4,K,W)*(L,M,X,Y) 494 160 127 99 108 32 18
YSC060A(3,4,K,W)*(H,Z) 522 169 134 105 114 32 18
YSC060E(1,3,4,W) 613 190 158 110 155 31 19
YSC072A(3,4,K,W)*(L,X) 720 245 188 129 158 39 21
YSC072A(3,4,W)*(M,Y) 731 248 192 131 160 39 21
YSC072A(3,4,K,W)*(H,Z) 735 249 193 132 161 39 21
YSC072E 793 304 146 219 124 41 23
YSC090A(3,4,K,W)*(L,X) 725 230 203 142 150 42 21
YSC090A(3,4,W)*(M,Y) 729 231 204 143 151 42 21
YSC090A(3,4,K,W)*(H,Z) 741 234 208 146 153 42 21
YSC092A(3,4,W)*(L,X) 806 273 217 143 172 40 21
YSC092A(3,4,W)*(M,Y) 810 274 219 144 173 40 21
YSC092A(3,4,W)*(H,Z) 822 277 222 147 175 40 21
YSC092E 916 370 160 265 121 41 22
YSC102A(3,4,K,W)*(L,X) 883 293 238 161 191 40 21
YSC102A(3,4,W)*(M,Y) 887 294 239 162 192 40 21
YSC102A(3,4,K,W)*(H,Z) 899 297 243 165 194 40 21
YSC102E 953 371 173 277 132 42 23
YSC120A(3,4,K,W)*(L,X) 933 310 253 171 198 40 21
YSC120A(3,4,W)*(M,Y) 945 313 257 174 200 40 21
YSC120A(3,4,K,W)*(H,Z) 958 317 261 177 202 40 21
YSC120E 1058 403 201 297 157 42 23
YHC036A1*(L,M,X,Y) 470 150 120 95 105 32 19
YHC036A1*(H,Z) 497 158 128 101 110 32 19
YHC033A(3,4,W)*(L,M,X,Y) 537 159 139 126 111 32 19
YHC036A(3,4,W)*(L,M,X,Y) 470 150 120 95 105 32 19
YHC033A(3,4,W)*(H,Z) 537 159 139 126 111 32 19
YHC036A(3,4,W)*(H,Z) 497 158 128 101 110 32 19
Installation

RT-SVX21F-EN 17
Installation
YHC036E1, E3, E4 544 127 103 204 110 39 26
YHC048A1*(M,Y) 511 157 126 108 121 32 20
YHC048A1*(H,Z) 539 166 133 114 126 32 20
YHC043A(3,4,W)*(L,M,X,Y) 577 167 144 139 127 32 20
YHC048A(3,4,W)*(L,M,X,Y) 511 157 126 108 121 32 20
YHC043A(3,4,W)*(H,Z) 577 167 144 139 127 32 20
YHC048A(3,4,W)*(H,Z) 539 166 133 114 126 32 20
YHC048E1, E3, E4 790 173 145 266 141 40 25
YHC060A1*(L,M) 562 176 137 116 133 31 20
YHC060A1*(H,Z) 574 179 140 119 136 32 20
YHC060A(3,4,W)*(L,M,X,Y) 550 175 133 110 131 31 19
YHC063A(3,4,W)*(L,M,X,Y) 612 180 151 144 137 31 19
YHC060A(3,4,W)*(H,Z) 561 178 137 113 134 31 19
YHC063A(3,4,W)*(H,Z) 561 178 137 113 134 31 19
YHC060E1, E3, E4 748 222 92 345 89 41 24
YHC072A(3,4,W)*(L,X) 756 245 193 137 181 39 22
YHC072A(3,4,W)*(M,Y) 768 248 197 140 183 39 22
YHC072A(3,4,W)*(H,Z) 772 249 198 141 184 39 22
YHC092A(3,4,W)*(L,X) 907 302 238 161 207 39 22
YHC092A(3,4,W)*(M,Y) 911 303 239 162 208 39 22
YHC092A(3,4,W)*(H,Z) 923 306 243 165 210 39 22
YHC102A(3,4,W)*(L,X) 942 306 247 171 217 39 22
YHC102A(3,4,W)*(M,Y) 946 307 248 172 218 39 22
YHC102A(3,4,W)*(H,Z) 957 310 252 175 220 40 22
YHC120A(3,4,W)*(L,X) 1035 336 269 191 240 39 22
YHC120A(3,4,W)*(M,Y) 1047 339 272 194 242 39 22
YHC120A(3,4,W) *(H,Z) 1060 342 277 197 245 40 22
Figure 7. Rigging and center of gravity
Table 1. Typical unit weights and point
loading data (continued)
Net
Weight
(lbs)
Corner Wt. (lbs) Center of Gravity (In.)
Unit Model A B C D Length Width
Table 2. Typical accessory weights
Weight - Net lbs
Option/Accessory
Description
YHC033
, 043,
063
YH/
YSC036-
060
YH/
YSC072-
120
Economizer 26 26 36
Motorized Damper 20 20 30
Manual Damper 16 16 26
Barometric Relief 7 7 10
Power Exhaust N/A N/A 80
Oversize Motor 5 5 8
Belt Drive Motor
(3 phase only) Standard 31 Standard
Hinged Access 10 10 12
Hail Guard 12 12 20
Through the Base:
Electrical 8813
Through the Base :
Gas 55 5
Unit Disconnect
Switch 55 5
Unit Circuit Breaker 5 5 5
Conv. Outlet:
Unpowered 22 2
Conv. Outlet:
Powered 38 38 38
TCI, LCI 1 1 1
NOVAR 8 8 8
HPC 1 1 1
Frostat 1 1 1
Crankcase Heater 1 1 1
Smoke Detector,
Return 77 7
Smoke Detector,
Supply 55 5
Clogged Filter
Switch 11 1
Fan Fail Switch 1 1 1
Discharge Air Tube 3 3 3
Roofcurb 70 70 115
LP Conversion Kit 3 3 3
All Zone Sensors 3 3 1
Hard Start Kit 3 3 N/A
Reheat Coil 15 15 25
Stainless Steel Heat
Exchanger 5510

18 RT-SVX21F-EN
Installation
Foundation
Horizontal Units
If the unit is installed at ground level,
elevate it above the snow line.
Provide concrete footings at each
support location with a “full
perimeter” support structure or a
slab foundation for support. Refer to
Table 1, “Typical unit weights and
point loading data,” on page 16 for
the unit’s operating and point loading
weights when constructing a footing
foundation.
If anchoring is required, anchor the
unit to the slab using hold down
bolts or isolators. Isolators should be
installed to minimize the
transmission of vibrations into the
building.
For rooftop applications, ensure the
roof is strong enough to support the
combined unit and support structural
weight. Refer to Tab l e 1, p. 16 for the
unit operating weights. If anchoring
is required, anchor the unit to the
roof with hold-down bolts or
isolators.
Check with a roofing contractor for
proper waterproofing procedures.
Figure 8. 3-5 ton R22, 3-5 ton Standard Efficiency R410a, 3 ton
High Efficiency R410a Horizontal Unit Supply & Return
Air Opening
Figure 9. 3-5 ton R22, 3-5 ton Standard Efficiency R410a, 3 ton
High Efficiency R410a Downflow Unit Supply & Return
Air Opening

RT-SVX21F-EN 19
Installation
Ductwork
Figure 8, p. 18 illustrates the supply
and return air openings as viewed
from the rear of the unit.
Elbows with turning vanes or
splitters are recommended to
minimize air noise due to turbulence
and to reduce static pressure.
Figure 10. 4-5 ton High Efficiency R410a, 6-10 ton R22 and R410a
Horizontal Unit Supply & Return Air Opening
Figure 11. 4-5 ton High Efficiency R410a, 6-10 ton R22 and R410a
Downflow Unit Supply & Return Air Openings
Supply
Return
When attaching the ductwork to the
unit, provide a water tight flexible
connector at the unit to prevent
operating sounds from transmitting
through the ductwork.
All outdoor ductwork between the
unit and the structure should be
weather proofed after installation is
completed.
Roof Curb
Downflow
The roof curbs for these units
consists of a “full perimeter”
enclosure to support the unit.
Before installing any roof curb,
verify;
• it is the correct curb for the unit,
• it includes the necessary gaskets
and hardware,
• the purposed installation
location provides the required
clearance for proper operation,
• the curb is level and square. The
top surface of the curb must be
true to assure an adequate curb-
to-unit seal.
WARNING
Combustible Materials!
Maintain proper clearance between
the unit heat exchanger, vent
surfaces and combustible materials.
Refer to unit nameplate and
installation instructions for proper
clearances. Improper clearances
could result in a fire hazard. Failure to
maintain proper clearances could
result in death or serious injury or
property damage.
Verify that appropriate materials
were used in the construction of roof
and ductwork. Combustible materials
should not be used in the
construction of ductwork or roof curb
that is in close proximity to heater
elements or any hot surface. Any
combustible material on the inside of
the unit base should be removed and
replaced with appropriate material.
Step-by-step curb assembly and
installation instructions ship with
each accessory roof curb kit. Follow
the instructions carefully to assure
proper fit-up when the unit is set into
place.
Note: To assure proper condensate
flow during operation, the
unit (and curb) must be level.
If the unit is elevated, a field
constructed catwalk around the unit
is strongly recommended to provide
easy access for unit maintenance and
service.
Recommendations for installing the
Supply Air and Return Air ductwork

20 RT-SVX21F-EN
Installation
joining the roof curb are included in
the curb instruction booklet. Curb
ductwork must be fabricated and
installed by the installing contractor
before the unit is set into place.
Note: For sound consideration, cut
only the holes in the roof
deck for the ductwork
penetrations. Do not cut out
the entire roof deck within the
curb perimeter.
If a Curb Accessory Kit is not
used:
• The ductwork can be attached
directly to the factory-provided
flanges around the unit’s supply
and return air openings. Be sure
to use flexible duct connections
at the unit.
• For “built-up” curbs supplied by
others, gaskets must be installed
around the curb perimeter flange
and the supply and return air
opening flanges.
Rigging
A Rigging illustration and Center-of-
Gravity dimensional data table is
shown in Figure 7, p. 17. Refer to the
typical unit operating weights table
before proceeding.
1. Remove all drill screws fastening
wood protection to metal
baserail. Remove all screws
securing wooden protection to
wooden top crate.
2. Remove Wooden Top Crate.
WARNING
Heavy Objects!
Do not use cables (chains or slings)
except as shown. Each of the cables
(chains or slings) used to lift the unit
must be capable of supporting the
entire weight of the unit. Lifting
cables (chains or slings) may not be
of the same length. Adjust as
necessary for even unit lift. Other
lifting arrangements may cause
equipment or property-only damage.
Failure to properly lift unit could
result in death or serious injury. See
details below.
3. Rig the unit as shown in Figure 7,
p. 17. Attach adequate strength
lifting slings to all four lifting
brackets in the unit base rail. Do
not use cables, chains, or slings
except as shown.
4. Install a lifting bar, as shown in
Figure 7, p . 17, to protect the unit
and to facilitate a uniform lift.
The minimum distance between
the lifting hook and the top of the
unit should be 7 feet.
5. Test-lift the unit to ensure it is
properly rigged and balanced,
make any necessary rigging
adjustments.
6. Lift the unit enough to allow the
removal of two Fork Lift brackets
and hardware. Remove the two
Fork Lift brackets, two metal
runners and three wooden
boards as shown in the following
Figure.
7. Downflow units; align the base
rail of the unit with the curb rail
while lowering the unit onto the
curb. Make sure that the gasket
on the curb is not damaged
while positioning the unit.
General Unit
Requirements
The checklist listed below is a
summary of the steps required to
successfully install a commercial
unit. This checklist is intended to
acquaint the installing personnel
with what is required in the
installation process. It does not
replace the detailed instructions
called out in the applicable sections
of this manual.
• Check the unit for shipping
damage and material shortage;
file a freight claim and notify
appropriate sales representative.
• Verify correct model, options and
voltage from unit nameplate.
Figure 12. Fork pocket
• Verify that the installation
location of the unit will provide
the required clearance for proper
operation.
• Assemble and install the roof
curb (if applicable). Refer to the
latest edition of the curb
installers guide that ships with
each curb kit.
• Fabricate and install ductwork;
secure ductwork to curb.
• Install pitch pocket for power
supply through building roof. (If
applicable)
• Rigging the unit.
• Set the unit onto the curb; check
for levelness.
• Ensure unit-to-curb seal is tight
and without buckles or cracks.
• Install and connect a condensate
drain line to the evaporator drain
connection.
Factory Installed Economizer
• Ensure the economizer has been
pulled out into the operating
position. Refer to the economizer
installers guide for proper
position and setup.
• Install all access panels.
Temperature Limit Switch
Usage for Gas Heat Units
Units are factory shipped in the
downflow discharge configuration
but can be field converted to a
horizontal discharge configuration.
Some, but not all units require a
different TCO1 limit switch, which is
attached to the combustion blower
motor if horizontal discharge
configuration is used.
Note: The following units require a
limit switch change out for
horizontal discharge. The
additional limit switch is
shipped attached to the
combustion blower housing.
Proceed to the Horizontal
Discharge Conversion, Step 5
on page 24 for the following
models "ONLY".
Y*C072A**(H,Z),
YSC090A**(H,Z),
YSC092A**(H,Z),
YHC092A**(M,Y),
YHC092A**(H,Z),
Y*C102A**(H,Z),