Trane YSC060E, YHC037E, YHC036E, YSC037E, YHC072E Installation & Operation Manual

Installation, Operation,
and Maintenance

Packaged Rooftop Air Conditioners
Precedent™ — Gas/Electric

3to10Tons–60Hz

Model Numbers

Only qualified personnel should install and service the equipment. The installation, starting up, and servicing
of heating, ventilating, and air-conditioning equipment can be hazardous and requires specific knowledge and
training. Improperly installed, adjusted or altered equipment by an unqualified person could result in death or
serious injury.When working on the equipment, observe all precautions in the literature and on the tags,
stickers, and labels that are attached to the equipment.

July 2014

YSC037E - YSC067E YHC037E - YHC067E
YSC036E - YSC060E YHC036E - YHC072E
YSC072F - YSC120F YHC120E
YHC048F - YHC060F YHC072F - YHC102F

SAFETY WARNING

RT-SVX21P-EN

Introduction

Read thismanual thoroughly before operating or servicing
this unit.

Warnings, Cautions, and Notices

Safety advisories appear throughout this manual as
required.Your personal safety and the proper operation of
this machine depend upon the strict observance of these
precautions.

The three types of advisories are defined as follows:

WARNING

Proper Field Wiring and Grounding
Required!

Failure to follow code could result in death or serious
injury. All field wiring MUST be performed by qualified
personnel. Improperly installed and grounded field
wiring poses FIRE and ELECTROCUTION hazards. To
avoid these hazards, you MUST follow requirements for
field wiring installation and grounding as described in
NEC and your local/state electrical codes.

WARNING

CAUTIONs

NOTICE

Indicates a potentially hazardous
situation which, if not avoided, could
result in death or serious injury.

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.

Indicates a situationthat could result in
equipment or property-damage only
accidents.

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.

Important 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.

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 PPE required for the work being
undertaken (Examples; cut resistant gloves/sleeves,
butyl gloves, safety glasses, hard hat/bump cap, fall
protection, electrical PPE and arc flash clothing).

ALWAYS refer to appropriate Material Safety Data

Sheets (MSDS)/Safety Data Sheets (SDS) and OSHA
guidelines for proper PPE.

• When working with or around hazardous chemicals,

ALWAYS refer to the appropriate MSDS/SDS and

OSHA/GHS (Global Harmonized System of
Classification and Labelling of Chemicals) guidelines
for information on allowable personal exposure
levels, proper respiratory protection and handling
instructions.

• If there is a risk of energized electrical contact, arc, or
flash, technicians MUST put on all PPE in accordance
with OSHA, NFPA 70E, or other country-specific
requirements for arc flash protection, PRIOR to
servicing the unit. NEVER PERFORM ANY
SWITCHING, DISCONNECTING, OR VOLTAGE

TESTING WITHOUT PROPER ELECTRICAL PPE AND
ARC FLASH CLOTHING. ENSURE ELECTRICAL

METERS AND EQUIPMENT ARE PROPERLY RATED
FOR INTENDED VOLTAGE.

Failure to follow instructions could result in death or
serious injury.

© 2014 Trane All rights reserved RT-SVX21P-EN

Copyright

This document and theinformation in it are the propertyof
Trane, and may not be used or reproduced in whole or in

part without written permission.Trane reserves the right
to revise this publication at any time, and to make changes
to its content without obligation to notify any person of
such revision or change.

Trademarks

All trademarks referenced in this document are the
trademarks of their respective owners.

Revision History

RT-SVX21P-EN (11 July 2014)

• Added Low Leak Economizer Factory and Field
Installed Option

RT-SVX21N-EN (04 Sep 2013)

• Added 575 volt to High Efficiency Units, updated

Wiring Matrix

• 5GIII update - Cooling and Gas/Electric -T/YHC120

• Human Interface - 5 inch ColorTouchscreen

Introduction

RT-SVX21P-EN 3

Table of Contents

Introduction ............................. 2

Warnings, Cautions, and Notices ........ 2

Important Environmental Concerns ..... 2

Important Responsible Refrigerant Practices
2

Copyright ............................. 3

Model Number Description ............... 6

Model Number Notes ................. 7

Model Number Description - 17 Plus ...... 8

Model Number Notes ................. 9

General Information .................... 10

Unit Inspection ..................... 10

Storage ........................... 10

Unit Nameplate .................... 10

Compressor Nameplate .............. 10

Microchannel Condenser Barcode ID . . . 10

Unit Description .................... 10

Economizer Control Actuator (Optional) 10

System Input Devices & Functions ..... 11

Low Pressure Control ................ 12

High Pressure Control ............... 12

Power Exhaust Control (Optional) ..... 12

Lead/Lag Control (Dual Circuit Only) . . . 12

Evaporator Frost Control ............. 13

Discharge Line Temp Switch (DLTS) . . . 14

Smoke Detector Sensor (Optional) ..... 14

Phase Monitor ..................... 14

Single Zone Variable Air Volume / Displace-

ment Ventilation (Optional) ........... 14

Human Interface - 5 Inch Color Touchscreen

(Optional) ......................... 14

Unit Dimensions ........................ 15

Installation ............................. 22

Pre-Installation ....................... 22

Procedure ........................... 22

Foundation .......................... 24

Horizontal Units .................... 24

Ductwork .............................25

Roof Curb ............................26

Downflow ..........................26

Rigging ............................27

General Unit Requirements .............27

Factory Installed Economizer ..........28

Temperature Limit Switch Usage for Gas

Heat Units ..........................28

Horizontal Discharge Conversion (3 to 5 Ton
Units)

................................29

TCO-1 Instructions .....................29

Horizontal Discharge Conversion (6 to 10 Ton
Units)

................................30

TCO1 Instructions .....................31

Return Air Smoke Detector .............31

Main Electrical Power Requirements .....32

Through-the-Base Gas Installation .......33

Requirements for Gas Heat .............33

Condensate Drain Configuration .........33

Filter Installation ......................34

Field Installed Power Wiring ............34

Main Unit Power ......................35

Standard Wiring .....................35

Optional TBUE Wiring (Through-the-Base

Electrical Option) ....................35

Field-Installed Control Wiring ..........36

Control Power Transformer ...........36

Controls Using 24 VAC ...............36

Controls using DC Analog Input/Outputs
(Standard Low Voltage Multi

conductor Wire) .....................36

DC Conductors ......................37

Space Temperature Averaging (ReliaTel™ On­ly)

...................................41

Pre-Start ................................44

Voltage Imbalance .....................44

Electrical Phasing (Three Phase Motors) ..44

Compressor Crankcase Heaters (Optional) 45

ReliaTel™ Controls ..................45

4 RT-SVX21P-EN

Table of Contents

Test Modes .......................... 46

ReliaTel™ Controls .................. 46

Electromechanical Controls Test

Procedure ......................... 47

Unit Start-Up ........................... 48

Verifying Proper Air Flow .............. 48

Units with 5-Tap Direct Drive Indoor Fan 48

Units with Belt Drive Indoor Fan ....... 48

Units with Direct Drive Indoor Fan - Electro-

mechanical Control ................. 49

ReliaTel™ Units with Direct Drive Indoor Fan
(7½ - 8½ Ton High Efficiency, 10 Ton Stan-

dard Efficiency) ..................... 49

Units with Constant CFM Direct Drive Indoor

Fan ............................... 50

17 Plus units with the constant CFM direct

drive indoor fan .................... 50

Variable Air Volume Applications (Traditional

VAV) .............................. 51

Supply Duct Static Pressure Control .... 52

Traditional VAV Standalone Operation . 52

Supply Air Temperature Reset ........ 52

Return Air Smoke Detector ........... 53

Economizer Start-Up ................ 53

Compressor Start-Up ................ 54

Dehumidification Option ............. 54

Gas Heat Units ..................... 54

Final System Setup ................. 55

Maintenance ........................... 56

Fan Belt Adjustment - Belt Drive Units ... 56

Monthly Maintenance ................. 57

Filters ............................. 57

Return Air Smoke Detector Maintenance 57

Condensate Overflow Switch ......... 57

Cooling Season .................... 57

Heating Season .................... 57

Coil Cleaning ....................... 58

Annual Maintenance .................. 59

Troubleshooting ........................ 60

ReliaTel™ Control .................... 60

System Status Checkout Procedure ..... 60

Method 1 ...........................60

Resetting Cooling and Ignition Lockouts .62

Zone Temperature Sensor (ZTS) Service Indi­cator

.................................62

Clogged Filter Switch .................62

Fan Failure Switch ...................62

Condensate Overflow Switch ..........62

Zone Temperature Sensor (ZTS) Tests ...62

Test 1 - Zone Temperature Thermistor

(ZTEMP) ...........................62

Test 2 - Cooling Set Point (CSP) and Heating

Set Point (HSP) ......................62

Test 3 - System Mode and Fan Selection .62

Test 4 - LED Indicator Test, (SYS ON, HEAT,

COOL & SERVICE) ...................63

Relative Humidity Sensor Test .........63

Programmable & Digital Zone Sensor

Test ...............................63

ReliaTel™ Refrigeration Module (RTRM) De-

fault Chart ..........................63

Unit Operation without a Zone Sensor . .63

Unit Economizer Control (ECA) Troubleshoot­ing

...................................64

ReliaTel™ Control ...................64

Electromechanical Control ............64

Unit Economizer Control (ECA) Test Proce­dures

................................66

Electromechanical Control ............66

Troubleshooting procedures for Direct Drive
Plenum Fan

...........................66

Unit Wiring Diagrams Numbers ...........67

Limited Warranty ........................69

Combination Gas Electric Air Conditioner .69

YCC, YCD, YCH, YCP, YSC and YHC (Parts On-

ly) .................................69

Models Less Than 20 Tons for Residential

Use* ..............................69

Combination Gas Electric Air Conditioner .69

YCZ, YCY, YCX, YCC, YCD, YCH, YCP, YHC

and YSC (Parts Only) .................69

Models Less Than 20 Tons for Commercial

Use* ..............................69

RT-SVX21P-EN 5

Model Number Description

YSC 036 E 3 R Z A **
123 456 7 8 9 10 11 1213

Digit 1 - Unit Type

Y DX Cooling, Gas Heat

Digit2-Efficiency

S Standard Efficiency
H High Efficiency

Digit 3 - Airflow

C Convertible

Digit 4,5,6 - Nominal Gross
Cooling Capacity (MBh)

036 3Ton
048 4Ton
060 5Ton
072 6Ton
090 7½Ton, Single Compressor
092 7½Ton, Dual Compressor
102 8½ Ton
120 10 Ton

Digit 7 - Major Design Sequence

E R-410A Refrigerant
F MicrochannelType Condenser

Coils

24

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

E Electromechanical
R ReliaTel™ Microprocessor

Digit 10 - Heating Capacity

L Low Heat
M Medium Heat
H High Heat
X Low Heat, Stainless Steel Heat

Exchanger

Y Medium Heat, Stainless Steel Heat

Exchanger

Z High Heat, Stainless Steel Heat

Exchanger

Digit 11 - Minor Design
Sequence

A First Sequence

B Second Sequence

21

20

Digit 12,13 - Service Sequence

** Factory Assigned

Digit 14 - Fresh Air Selection

0 No Fresh Air

A Manual Outside Air Damper 0-50%

B Motorized Outside Air Damper

C Economizer, Dry Bulb 0-100%

D Economizer, Dry Bulb 0-100%

E Economizer, Reference Enthalpy

F Economizer, Reference Enthalpy

G Economizer, Comparative

28

0-50%

without Barometric Relief

with Barometric Relief

7

7

0-100% without Barometric Relief

0-100% with Barometric Relief

3,7

Enthalpy 0-100% without

3,7

Barometric Relief

H Economizer, Comparative

Enthalpy 0-100% with Barometric

3,7

Relief

K Low Leak Economizer with

Barometric Relief

M Low Leak Economizer with Reference

Enthalpy with Barometric Relief

P Low Leak Economizer with

Comparative Enthalpy with
Barometric Relief

Digit 15 - Supply Fan/DriveType/
Motor

0 Standard Drive
1 Oversized Motor
2 Optional Belt Drive Motor
6 Single Zone VAV
7 Multi-Speed Indoor Fan
E VAV Supply Air Temperature Control

Standard Motor

Digit 16 - Hinged Service

Access/Filters

0 Standard Panels/Standard Filters

A Hinged Access Panels/Standard

Filters
B Standard Panels/2” MERV 8 Filters
C Hinged Access Panels/2” MERV 8

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

25

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 NoThrough-the-Base Provisions

A Through-the-Base Electric

B Through-the-Base Gas Piping
C Through-the-Base Electric and Gas

Piping

16

Digit 19 - Disconnect/Circuit
Breaker (three-phase only)

4

0 No Disconnect/No Circuit Breaker
1 Unit Mounted Non-Fused

Disconnect
2 Unit Mounted Circuit Breaker

Digit 20 - Convenience Outlet

0 No Convenience Outlet

A Unpowered Convenience Outlet

B Powered Convenience Outlet

(three-phase only)

3,7

Digit 21 - Communications
Options

3

0 No Communications Interface
1 Trane Communications Interface
2 LonTalk® Communications Interface
3 Novar 2024 Controls
4 Novar 3051 Controls without Zone

5 Novar 3051Controls Interface with

Sensor

30

DCV

30

30

6 BACnet® Communications Interface

Digit 22 - Refrigeration System

6

18

26

27

33

Option

0 Standard Refrigeration System
B Dehumidification Option

10

22,23

Digit 23 - Refrigeration Controls

Note: Applicable to Digit7=E,F

0 No Refrigeration Control
1 Frostat™
2 Crankcase Heater
3 Frostat™

11 ,29

11 ,29

and Crankcase Heater

Digit 24 - Smoke Detector

0 No Smoke Detector
A Return Air Smoke Detector
B Supply Air Smoke Detector
C Supply and Return Air Smoke

Detectors

D Plenum Smoke Detector

12,13

5

2

17

12,13

Digit 25 - System 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

Failure Switch

25

5 Clogged Filter Switch and Discharge

Air SensingTube

6 Fan Failure Switch and Discharge Air

SensingTube

14

14

7 Clogged Filter Switch, Fan Failure

Switch and Discharge Air
SensingTube

8 Novar Return Air Sensor

8

16

(NOVAR 2024)

9 Novar ZoneTemp Sensor

(NOVAR 3051)

14

15,30

19,30

A Condensate Drain Pan Overflow

Switch

B Clogged Filter Switch14and

Condensate Drain Pan Overflow
Switch

C Fan Failure Switch14and Condensate

8

8

Drain Pan Overflow Switch

D Discharge Air Sensing14and

Condensate Drain Pan Overflow
Switch

E Clogged Filter Switch14, Fan Failure

Switch14and Condensate Drain Pan
Overflow Switch

9

F Clogged Filter Switch14, Discharge

Air SensingTube14and Condensate
Drain Pan Overflow Switch

G Fan Failure Switch, Discharge Air

14

14

14

14

14

2

6 RT-SVX21P-EN

Model Number Description

14

SensingTube
Drain Pan Overflow Switch

H Clogged Filter Switch14, Fan Failure

Switch14, Discharge Air Sensing
and Condensate Drain Pan Overflow
Switch

and Condensate

14

Digit 26 - System Monitoring
Controls

0 No Monitoring Controls

A Demand Control Ventilation

B Low Leak Economizer with FDD

C FDD (Fault Detection & Diagnostics)

31,32

(CO2)

(Fault Detection & Diagnostics)

with DCV (Demand Control

Ventilation)

Digit 27 - Unit Hardware
Enhancements

0 No Enhancements
1 Stainless Steel Drain Pan

Digit 31 - Advanced Unit
Controls

0 Standard Unit Controls
1 Human Interface

Model Number Notes

1. Available on 3-5 ton models.

2. Crankcase heaters are optional
on (Y)SC (036, 048, 060, 072, 090,
102,120); standard on (Y)HC (036,
048, 060, 072, 092, 102, 120).

3. Not available with
electromechanical controls.

4. Manual outside air damper will
ship factory supplied within the
unit, but must be field installed.

5. High pressurecontrol isstandard
on all units.

6. On 3-5 ton, multispeed direct
drive is standard on single phase
and 15 SEER. On 6-10 ton,
multispeed direct drive is
standard on all 10 ton and 7.5-8.5
ton high efficiency. Belt drive is
standard on all other units.

Digit 15 = 0

Standard Efficiency
1 Phase = High Efficiency Multispeed Direct
Drive Motor
3 Phase (3-8½ Ton) = Belt Drive
3 Phase (10 Ton) = Ultra High Efficiency
Direct Drive Plenum Fan
High Efficiency
1 Phase = High Efficiency Multispeed Direct
Drive Motor
3 Phase (3-5 ton) = High Efficiency
Multispeed Direct Drive Motor
3 Phase (3-5 ton w/Dehumidification) = Belt
Drive Motor
3 Phase (7½-10 ton) = Ultra High Efficiency
Direct Drive Plenum Fan

7. Economizer with Barometric
Relief is for downflow configured
units only. Order Economizer
without Barometric Relief for
horizontal configuration.
Barometric Relief for horizontal
configured units mustbe ordered
as field-installed accessory.

8. Through-the-base electric
required when ordering
disconnect/circuit breaker
options.

9. Requires use of Disconnect or
Circuit Breaker.

Not Available

Standard Efficiency
10 Ton w/575V
High Efficiency 575V (any unit)
3-5 Ton w/ Standard Indoor Motor (except
dehumidification) and w/460V

10. Standard metering devices are

TXVs.

11. Frostat cannot be field installed in
electro-mechanical units.

12. The return air smoke detector
may not fitup or workproperly 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.

13. Return Air Smoke Detector
cannot be ordered with Novar
Controls.

14. These options are standard when
ordering Novar Controls.

15. This option is used when
ordering Novar Controls.

16. Includes gas piping and shutoff
(field assembly required).

17. Not available with high
temperature duct sensor
accessory.

18. Digit 15 = 2

Standard Efficiency
1 Phase = Not Available
3 Phase = Not Available
High Efficiency
1 Phase = Not Available
3 Phase (3-5 ton) = May be Ordered
3 Phase (3-5 ton w/Dehumidification) = Not
Available
3 Phase (6-10 ton) = Not Available

19. Novar Sensor utilized with
Digit 21 = (4)Novar 3051 Controls
without Zone Sensor.

20. Available for 10 ton standard
efficiency models only.

21. Available for 3, 4, 5, 6, 7½, 8½ ton
standard/high efficiency models
only.

22. Requires selection of 2” Pleated
Filters (option B or C) for Digit 16.

23. Not available on all single phase
or standard efficiency.

24. Standard onYSC 6, 7½ (single
and dual systems), 8½, 10 ton
standard efficiency models and

YHC 4, 5, 6, 7½, 8½ ton high

efficiency models (except for
4,5,6 ton dehumidification
models).

25. Epoxy coil and epoxy with
hailguard options are not
available for units with
microchannel condenser coil.

26. Single ZoneVAV is only available
on 7.5-10 ton high efficiency and
10 ton standard efficiency
products with ReliaTel™ controls.

27. Multi-speed indoor fan available
only on 7.5 & 8.5 ton high
efficiency, and 10 ton products
with ReliaTel™ controls.

28. Motorized Outside Air Damper is
not available on Multi-Speed or
SZVAV (Single Zone Variable Air

Volume) products.

29. Frostat standard on Multi-Speed
and SZVAV (Single ZoneVariable

Air Volume) products.

30. Novar is not available with SZVAV
products.

31. Demand Control Ventilation not
available with electromechanical
controls.

32. Demand Control Ventilation
Option includes wiring only.The
C0

sensor is afield-installed only

2

option.

33. Discharge Air Sensing is also
standard equipment on units
with Single Zone and Supply Air

Temperature Control VAV.

RT-SVX21P-EN 7

Model Number Description - 17 Plus

YHC 037 E 3 R Z B **
123 456 7 8 9 10 11 1213

Digit 1 - Unit Type

T DX Cooling
Y DX Cooling, Gas Heat

Digit2-Efficiency

S Standard Efficiency
H High Efficiency

Digit 3 - Airflow

C Convertible

Digit 4,5,6 - Nominal Gross
Cooling Capacity (MBh)

037 3Ton
047 4Ton
067 5Ton

Digit 7 - Major Design Sequence

E R-410A Refrigerant

Digit 8 - Voltage Selection

3 208-230/60/3
4 460/60/3

Digit 9 - Unit Controls

R ReliaTel™ Microprocessor

Digit 10 - Heating Capacity

0=No Electric Heat G=18 kW (1&3 phase)
B=6 kW (3 phase) J=23 kW (3 phase)
E=12 kW (3 phase)

L Low Heat
M Medium Heat
H High Heat
X Low Heat, Stainless Steel Heat

Exchanger

Y Medium Heat, Stainless Steel Heat

Exchanger

Z High Heat, Stainless Steel Heat

Exchanger

Digit 11 - Minor Design
Sequence

A First Sequence

16

Digit 12,13 - Service Sequence

** Factory Assigned

Digit 14 - Fresh Air Selection

0 No Fresh Air

A Manual Outside Air Damper 0-50%

B Motorized Outside Air Damper

0-50%

C Economizer, Dry Bulb 0-100%

without Barometric Relief

D Economizer, Dry Bulb 0-100%

with Barometric Relief

E Economizer, Reference Enthalpy

0-100% without Barometric Relief

F Economizer, Reference Enthalpy

0-100% with Barometric Relief

G Economizer, Comparative

Enthalpy 0-100% without
Barometric Relief

5

H Economizer, Comparative

Enthalpy 0-100% with Barometric

5

Relief

K Low Leak Economizer with

Barometric Relief

5

5

5

5

M Low Leak Economizer with Reference

Enthalpy with Barometric Relief

P Low Leak Economizer with

Comparative Enthalpy with
Barometric Relief

Digit 15 - Supply Fan/DriveType/
Motor

0 Standard Drive
6 Single Zone VAV
E VAV Supply Air Temperature Control

Standard Motor

4

21

21

Digit 16 - Hinged Service

Access/Filters

0 Standard Panels/Standard Filters

A Hinged Access Panels/Standard

Filters
B Standard Panels/2” MERV 8 Filters
C Hinged Access Panels/2” MERV 8

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 NoThrough-the-Base Provisions

A Through-the-Base Electric

B Through-the-Base Gas Piping
C Through-the-Base Electric and Gas

Piping

13

Digit 19 - Disconnect/Circuit
Breaker (three-phase only)

0 No Disconnect/No Circuit Breaker
1 Unit Mounted Non-Fused

2

Disconnect

6

2 Unit Mounted Circuit Breaker

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
1 Trane Communications Interface
2 LonTalk® Communications

Interface
3 Novar 2024 Controls
4 Novar 3051 Controls without Zone

Sensor
5 Novar 3051Controls Interface with

DCV
6 BACnet® Communications Interface

Digit 22 - Refrigeration System
Option

0 Standard Refrigeration System
B Dehumidification Option

8

17

Digit 23 - Refrigeration Controls

Note: Applicable to Digit7=E

0 No Refrigeration Control
1 Frostat
2 Crankcase Heater
3 Frostat and Crankcase Heater

Digit 24 - Smoke Detector

0 No Smoke Detector
A Return Air Smoke Detector
B Supply Air Smoke Detector
C Supply and Return Air Smoke

Detectors
D Plenum Smoke Detector

9,10

3

1

1

14

9,10

Digit 25 - System Monitoring
Controls

0 No Monitoring Control
1 Clogged Filter Switch
2 Fan Failure Switch
3 Discharge Air Sensing Tube

6

13

4 Clogged Filter Switch and Fan

Failure Switch

11

5 Clogged Filter Switch and Discharge

Air SensingTube

6 Fan Failure Switch and Discharge Air

SensingTube

11

7 Clogged Filter Switch, Fan Failure

Switch and Discharge Air

SensingTube
8 Novar Return Air Sensor

6

(NOVAR 2024)
9 Novar ZoneTemp Sensor

(NOVAR 3051)

11

12,20

15,20

A Condensate Drain Pan Overflow

Switch
B Clogged Filter Switch11and

Condensate Drain Pan Overflow

Switch
C Fan Failure Switch11and Condensate

Drain Pan Overflow Switch
D Discharge Air Sensing11and

Condensate Drain Pan Overflow

Switch
E Clogged Filter Switch11, Fan Failure

Switch11and Condensate Drain Pan

Overflow Switch
F Clogged Filter Switch11, Discharge

Air SensingTube11and Condensate

11

11

11

11

11

8 RT-SVX21P-EN

Model Number Description - 17 Plus

Drain Pan Overflow Switch

G Fan Failure Switch

SensingTube11and Condensate
Drain Pan Overflow Switch

H Clogged Filter Switch11, Fan Failure

Switch11, Discharge Air Sensing
and Condensate Drain Pan Overflow
Switch

11

, Discharge Air

11

Digit 26 - System Monitoring
Controls

0 No Monitoring Controls

A Demand Control Ventilation

B Low Leak Economizer with FDD

C FDD (Fault Detection & Diagnostics)

18,19

(CO2)

(Fault Detection & Diagnostics)

with DCV (Demand Control

Ventilation)

Digit 27 - Unit Hardware
Enhancements

0 No Enhancements
1 Stainless Steel Drain Pan

Digit 31 - Advanced Unit
Controls

0 Standard Unit Controls
1 Human Interface

Model Number Notes

1. Standard on all variable stage
units.

2. Manual outside air damper will
ship factory supplied within the
unit, but must be field installed.

3. High pressurecontrol isstandard
on all units.

4. Constant CFM direct drive is
standard for 3-5Ton variable
stage units.

Digit 15 = 0, 6

3 Phase (3-5 ton) - High Efficiency Constant
cfm

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 mustbe 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.

Not Available

High Efficiency
3-5 ton w/Standard Indoor Motor w/460V

8. Standard metering devices are
TXVs.

9. The return air smoke detector

may not fitup or workproperly 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.

10. Return Air Smoke Detector

cannot be ordered with Novar
Controls.

11. These options are standard when

ordering Novar Controls.

12. This option is used when

ordering Novar Controls.

13. Includes gas piping and shutoff

(field assembly required).

14. Not available with high

temperature duct sensor
accessory.

15. Novar Sensor utilized with

Digit 21 = (4)Novar 3051 Controls
without Zone Sensor.

16. Available forT/Y 3,4,5 ton high

efficiency models.

17. Requires selection of 2” Pleated

Filters (option B or C) for Digit 16.

18. Demand Control Ventilation not

available with electromechanical
controls.

19. Demand Control Ventilation

Option includes wiring only.The
CO

sensor is a field-installed

2

only option.

20. Novar is not available with SZVAV

products.

21. Discharge Air Sensing is also

standard equipment on units
with Single Zone and Supply Air

Temperature Control VAV.

RT-SVX21P-EN 9

General Information

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 typeand extent ofthe 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,
Supply Air and Return Air 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 “Unit Start-Up,” p. 48”.

The manufacturer will not assume any responsibility for

equipment damage resulting from condensate
accumulation on the unit’s electrical and/or mechanical
components.

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 forthe compressors are locatedon the side

of the compressor.

Microchannel Condenser Barcode ID

Barcode decal used for condenser coil part identification
can be located on the vertical header and top of coil's inlet/
outlet side.

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 coilsare either aluminum fin, mechanically

bonded to copper tubing or all aluminum microchannel.

Direct-drive, vertical discharge condenser fans are
provided with built-in thermal overload protection.

There are two control systems offered for these units.The

electromechanical 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 inresponse 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)

Electromechanical Control

The ECA monitors the mixedair 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, CO
ambient dry bulb/enthalpy sensor or comparative
humidity (return air humidity against ambient humidity)

setpoint, CO2, and

2

10 RT-SVX21P-EN

General Information

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. Itallows the control and monitoringof 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.

RBCI - ReliaTel™ BACnet Communications
Interface (Optional)

This module is used when the application calls foran open

BACnet protocol. It allows the control and monitoring of
the system through an ICS panel.The module can be
ordered from the factory or as a kit to be field installed.
Follow the installation instructions that ships with each kit
when field installation is necessary.

RTOM - ReliaTel™ Options Module (Standard
on 17 Plus, 7.5 Ton & 8.5 Ton High Efficiency
with ReliaTel, 10Ton with ReliaTel)

The RTOMmonitors the supply fan proving, cloggedfilter,

supply air temperature, exhaust fan setpoint, supply air
tempering, Frostat™, smoke detector, and Variable Speed
Fan Control (17 Plus units only). 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 dependsupon the type of zone sensor or
thermostat selected to interface with the RTRM.

The descriptions of the following basic InputDevices 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
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 closedfor 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.

Condensate Drain Pan Overflow Switch
(Optional)

ReliaTel™ Option

This input incorporates the Condensate Overflow Switch

(COF) mounted on the drain pan and the ReliaTel Options
Module (RTOM).When the condensate level reaches the
trip point for 6 continuous seconds, the RTOM will shut
down all unit functions until the overflow condition has
cleared.The unit will return to normal operation after 6
continuous seconds with the COF in a non-tripped
condition. If the condensate level causes unit shutdown
more than 2 times in a 3 days period, the unit will be
locked-out of operation requiring manual reset of
diagnostic system through Zone Sensor or Building
Automation System (BAS). Cycling unit power will also
clear the fault.

Electromechanical Option

This input incorporates the condensate overflow switch

(COF), COF Relay, COFTime Delay.When the condensate
level reaches the trip point, the COF relay energizes and
opens the 24VAC control circuit which disables the unit.
Once the 24VAC control circuitis opened, adelay timer will
prevent unit start-up for three minutes.

RT-SVX21P-EN 11

General Information

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

ReliaTel™ Control

The high pressure controls are wiredin 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. Lead/
Lag is not available on Multi-Speed Indoor Fan, or Single
Zone Variable Air Volume (SZVAV) products.

Zone Sensor Module (ZSM) (BAYSENS106*)

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) (BAYSENS108*)

This electronic sensorfeatures 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*.

Zone Sensor (BAYSENS110*)

This electronic sensorfeatures 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
BAYSENS077*.

Wall Mounted Relative Humidity Sensor

(BAYSENS036*)

Field installed, wall mounted humidity sensor is used to
control activation of Enhanced Dehumidification and the
Hot Gas Reheat Dehumidification options. Humidity set
points can beselected for relativehumidity levels between

12 RT-SVX21P-EN

General Information

40% and 60% by adjusting the DEHUMID setting on the
ReliaTel Options Module. See Figure 42, p. 37.

Duct Mounted Relative Humidity Sensor
(BAYSENS037*)

Field installed, duct mounted humidity sensor is used to
control activation of Enhanced Dehumidification and the
hot gas reheat dehumidification options. Humidity set
points can beselected for relativehumidity levels between
40% and 60% by adjusting the DEHUMID setting on the
ReliaTel Options Module. See Figure 42, p. 37.

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

º F. The heating set point ranges between 43 and 96ºF.

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 ratedfor 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”,
SERVICE).

Four (4) wires from the RTRM should be connected to the
appropriate terminals (7, 8,9&10)ontheZSM.

Remote Zone Sensor (BAYSENS073*)

This electronic sensor features remote zone sensing and

timed override with override cancellation. It is used with a

Trane Integrated Comfort™ building management

system.

Remote Zone Sensor (BAYSENS074*)

This electronic sensor features single setpoint capability

and timed override with override cancellation. It is used
with aTrane Integrated Comfort™ building management
system.

Remote Zone Sensor (BAYSENS016*)

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 proceduresvary
according to the particular application and equipment
involved. Refer to the unit’s wiring diagrams for proper
connections.

Remote Zone Sensor (BAYSENS077*)

This electronic sensor can be used with BAYSENS106*,

108*, 110*, 119* Remote Panels.When this sensor is wired
to a BAYSENS119* Remote Panel, wiring must be 18 AWG
ShieldedTwisted Pair (Belden 8760 or equivalent). Refer to
the specific Remote Panel for wiring details.

Wireless Zone Sensor (BAYSENS050*)

This electronic sensor features five system settings (Auto,

Off, Cool, Heat, and Emergency Heat) and with On and

Auto fan settings. It is amanual or auto changeover control

with dual setpoint capability. Other features include a
timed override function, lockable system settings, and
Fahrenheit or Celsius temperature display. Included with
the wireless zone sensor will be a receiver that is to be
mounted inside the unit, a mounting bracket, and a wire
harness.

Electromechanical Control

The unit must have a thermostat to operate.

•BAYSTAT151

• Single Stage - 1 Heat/1 Cool

•BAYSTAT155

• Multi Stage - 3 Heat/2 Cool - Can be Used for

Economizer Operation

• BAYSENS150

• Multi stage - 3 Heat/2 Cool Programmable

Thermostat

High Temperature Sensor (BAYFRST001*)

This sensor connects to the RTRM Emergency Stop Input

on the LTB andprovides high limit “shutdown” of the unit.

The sensor is used to detect high temperatures due to a

high thermal event 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 135ºF. The
supply air duct sensor (X1310004002) is set to open at
240ºF. The control can be reset after the temperature has
been lowered approximately 25ºF below the cutout
setpoint.

Evaporator Frost Control

ReliaTel™ Option

This input incorporates the Frostat™ control (FOS)

mounted in the indoor coil circuit and can be activated by

RT-SVX21P-EN 13

General Information

closing a field supplied contact installed in parallel with
the FOS.

If this circuit is closed before thecompressor is started, the
compressor will not be allowed to operate. Anytime this
circuit is closed 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 open.

Frostat is standard on multi-speed indoor motors and
single zone VAV products (SZVAV).

Electromechanical Option

This input incorporates the Frostat™ control (FOS)

mounted in the indoor coil circuit and can be activated by
opening a field supplied contact installedin 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.

Discharge Line Temp Switch (DLTS)

The DLTS is looped in series with HPC and LPC. It prevents

compressor from overheating (over 300 Fº dome temp) in
case of indoor fan failure (cooling) or outdoor fan failure
(heating).

Smoke Detector Sensor (Optional)

This sensor provideshigh limit“shutdown” of theunit and

requires a manual reset.The sensor is used to detect
smoke in the air conditioning or ventilation ducts.

Notes:

• The supply air smoke detector samples supply air.The

return and plenum air smoke detectors sample return
air.The smoke detectors are designed to shut off the
unit if smoke is sensed.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 its
design function.

• 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.

• 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.

Phase Monitor

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.

Single Zone Variable Air Volume /
Displacement Ventilation (Optional)

This sensor offers full supply fan modulation across the

available airflow range. In addition to full supply fan
modulation, the unit controls the discharge air
temperature to a varying discharge air temperature
setpoint in order to maintain SpaceTemperature.

Human Interface - 5 Inch Color

Touchscreen (Optional)

The 5 inchColorTouchscreenHuman Interface provides an

intuitive user interface to the rooftop unit that speeds up
unit commissioning, shortens unit troubleshooting times,
and enhances preventative maintenance measures.The
human interface includes several features including:

• Data trending capabilities by means of time series
graphs

• Historical alarm messages

• Real-time sensor measurements

• On board system setpoints

• USB port that enables the downloading of component
runtime information as well as trended historical
sensor data

• Customized reports

14 RT-SVX21P-EN

Unit Dimensions

Figure 1, p. 15 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

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.

YSC036-060E & YHC036E, YHC037E Units

RT-SVX21P-EN 15

YSC072-120F, YHC048-102F, YHC047-120E Units

Unit Dimensions

44 MMMM

44 MMMM

1038 MMMM

1053 MMMM

Figure 2. 3-5 ton standard efficiency, 3 ton high efficiency

Notes:

1. All dimensions are in inches/millimeters.

2. ½ NPT Gas Connection

Figure 3. 3-5 ton standard efficiency, 3 ton high efficiency - roof curb

Note: All dimensions are in inches/millimeters.

44

44

7

1038

1053

16 RT-SVX21P-EN

Figure 4. 3-5 ton standard efficiency, 3 ton high efficiency - unit clearance and roof opening

Note: All dimensions are in inches/millimeters.

CLEARANCE 36” (914 MM)

Figure 5. 6, 7½ (single) ton standard efficiency, 4-5 ton high efficiency

Note: All dimensions are in inches/millimeters.

Unit Dimensions

RT-SVX21P-EN 17

Unit Dimensions

Figure 6. 6, 7½ (single) ton standard efficiency, 4-5 ton high efficiency - roof curb

Note: All dimensions are in inches/millimeters.

(356 MM)

(2130 MM)

Figure 7. 6, 7½ (single) ton standard efficiency, 4-5 ton high efficiency - unit clearance and roof opening

Note: All dimensions are in inches/millimeters.

18 RT-SVX21P-EN

Unit Dimensions

Figure 8. 7½ ton (dual) - 10 ton standard efficiency,6-8½(MCHE) ton high efficiency, 6 ton dehumidification

Note: All dimensions are in inches/millimeters.

(TC MODELS)

2” ELECTRICAL CONNECTION

(SINGLE POINT POWER
WHEN HEAT INSTALLED)

1/2 NPT GAS CONNECTION

(80 mbh, 120 mbh)

3/4 NPT GAS CONNECTION

(150 mbh, 200 mbh, 250 mbh)

(YC MODELS)

Figure 9. 7½ ton (dual) - 10 ton standard efficiency,6-8½(MCHE) ton high efficiency, 6 ton dehumidification

roof curb

Note: All dimensions are in inches/millimeters.

(356 MM)

(2130 MM)

RT-SVX21P-EN 19

Unit Dimensions

(

)

(

)

(

)

Figure 10. 7½ ton (dual) - 10 tons standard efficiency,6-7½(MCHE) ton high efficiency, 6 ton dehumidification

unit clearance and roof opening

Note: All dimensions are in inches/millimeters.

Figure 11. 10 ton high efficiency

Notes:

1. All dimensions are in inches/millimeters.

2. ½ or ¾ NPT Gas Connection

UNIT CONTROL WIRE
7/8”

22MM

DIA HOLE

CONTROL BOX SECTION

ACCESS PANEL

EVAPORATOR SECTION

ACCESS PANEL

ALTERNATE CONDENSATE DRAIN
CONNECTION 3/4-14 NPT DIA.HO LE

27 5/8”

701 MM

47 7/8”

1216 MM

99 11/16”
2532 MM

1/2 NPT GAS CONNECTION

˄80 mbh, 120mbh˅;

3/4 NPT GAS CONNECTION

150mbh, 200mbh, 250mbh

or
2” ELECTRICAL CONNECTION
(SINGLE POINT POWER WHEN
HEAT INSTALLED)

UNIT POWER WIRE

35MM

1 3/8”

DIA. HOLE

INDOOR TOP PANEL

SERVICE GAUGE PORT
ACCESS 1 3/8” (35MM) DIA.
HOLE

OUTDOOR TOP PANEL

63 3/16”

1605 MM

COMPRESSOR ACCESS PANEL

50 7/8”
1292 MM

CONDENSER COIL

20 RT-SVX21P-EN

Figure 12. 10 ton high efficiency - roof curb

(

)

(

)

(

)

(

)

(

)

(

)

(

)

(

)

(

)

Notes:

1. All dimensions are in inches/millimeters.

34 3/8”

(873 MM)

84 1/2”

(2146 MM)

14”

356 MM

13/4”

44 MM

56 3/8”

(1432 MM)

25 MM

1”

51 MM

2”

18 1/2”

(470 MM)

2”

51 MM

CLEARANCE36”(914MM) FOR DOWNFLOW

CLEARANCE 18” (457 MM) FOR HORIZONTAL

65/8”

168 MM

1”

25 MM

34 3/8”

(873 MM)

18 1/2”

(470 MM)

1”

25 MM

(2130 MM)

83 7/8”

80 1/2”

(2045 MM)

60 3/8”

(1534 MM)

59 7/8”

1521 MM

Unit Dimensions

Figure 13. 10 ton high efficiency- unit clearance and roof opening

Notes:

1. All dimensions are in inches/millimeters.

99 11/16”

(2532 MM)

63 3/16”

(1605 MM)

RT-SVX21P-EN 21

Installation

Pre-Installation

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. You MUST wear all necessary Personal
Protective Equipment (PPE) including gloves, eye
protection, mask, long sleeves and pants when working
with products containing fiberglass wool. Exposure to
glass wool fibers without all necessary PPE equipment
could result in cancer, respiratory, skin or eye irritation,
which could result in death or serious injury.

Precautionary Measures

• Avoid breathing fiberglass dust.

• Use a NIOSH approved dust/mist respirator.

• Avoid contact with the skinor 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.

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 unit dropping and
possibly crushing operator/technician which could
result in death or serious injury and possible equipment
or property-only damage.

.

Figure 14. Corner weights

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.

Procedure

WARNING

Heavy Objects!

Ensure that all the lifting equipment used is properly
rated for the weight of the unit being lifted. Each of the
cables (chains or slings), hooks, and shackles 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 could cause
equipment or property damage. Failure to follow
instructions above or properly lift unit could result in
unit dropping and possibly crushing operator/
technician which could result in death or serious injury.

22 RT-SVX21P-EN

Installation

Table 1. Maximum unit & corner weights (lbs) and center of gravity dimensions (in.) - gas/electric models

Tons Shipping Net A B C D Length Width

3 YSC036E/YHC036E 607 532 165 137 95 134 31 19
4 YSC048E 638 563 175 145 101 142 31 19
5 YSC060E 688 613 190 158 110 155 31 19

6 YSC072F 805 710 222 217 121 150 41 22
7½ YSC090F 862 767 243 221 155 149 45 21
7½ YSC092F 990 847 265 249 173 160 46 21
8½ YSC102F 1047 904 279 252 187 186 44 22

10 YSC120F 1156 1058 345 242 258 213 41 23

3 YHC037E 676 606 178 162 126 139 33 19

4 YHC048E/YHC047E 858 763 238 200 148 176 40 23

4 YHC048F 806 711 226 199 144 143 44 22

5 YHC060E/YHC067E 917 822 261 218 156 187 40 22

5 YHC060F 850 755 239 214 152 151 44 21

6 YHC072E 1025 927 296 198 205 228 41 24

6 YHC072F 965 822 250 245 174 153 47 21
7½ YHC092F 1124 1026 340 233 249 204 41 23
7½ YHC092F 1144 1046 342 241 257 206 49 23
8½ YHC102F 1133 1035 341 236 253 205 49 23
8½ YHC102F 1153 1055 343 244 261 207 49 23

10 YHC120E 1589 1372 384 378 302 308 49 28

(a)Weights are approximate.
(b)Corner weights are given for information only.

Model No.

Unit

Maximum Model Weights

(a)

Corner Weights

(b)

Center of Gravity (in.)

Figure 15. Rigging and center of gravity

RT-SVX21P-EN 23

Installation

Table 2. Factory installed options (fiops)/accessory net weights (lbs)

YSC036E-060E

YHC036E,YHC037E

Net Weight Net Weight Net Weight Net Weight Net Weight

Accessory 3-5 Ton 4-5 Ton 6-8½ Ton 7½, 8½, 10 Ton 10 Ton

Barometric Relief 7 10 10 10 10
Belt Drive Option (3 phase only) 31 31 — — —
Coil Guards 12 20 20 20 30
Economizer 26 36 36 36 36
Hinged Doors 10 12 12 12 12
Low Leak Economizer 68 93 93 93 93
Manual Outside Air Damper 16 26 26 26 26
Motorized Outside Air Damper 20 30 30 30 30
Novar Control 8 8888
Oversized Motor 5 8 8 — —
Powered Convenience Outlet 38 38 38 38 50
Powered Exhaust 40 40 80 80 80
Reheat Coil 12 14 15 — 30
Roof Curb 61 78 78 78 89
Smoke Detector, Supply 5 5555
Smoke Detector, Return 7 7777
Stainless Steel Heat Exchanger 4 6666
Through-the-Base Electrical(c) 8 13131313
Through-the-Base Gas 5 5555
Unit Mounted Circuit Breaker 5 5555
Unit Mounted Disconnect 5 5555
460V/575V IDM Transformer

(a)Weights for options not listed are <5 lbs.
(b)Net weight should be added to unit weight when ordering factory-installed accessories.
(c) Apply weight with all 460V and 575V 17 Plus Two-Stage Cooling units.

(c)

29 29 — — —

YHC047E-067E

YHC048F-060F

(a),(b)

YSC072F-102F

YHC072E/F

YHC092F-102F,

YSC120F YHC120E

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, p. 23 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.

24 RT-SVX21P-EN

WARNING

Risk of Roof Collapsing!

Confirm with a structural engineer that the roof
structure is strong enough to support the combined
weight of the roof curb and the unit. Refer to Table 1,

p. 23 for typical unit and curb weights. Failure to ensure

proper structural roof support could cause the roof to
collapse, which could result in death or serious injury
and property damage.

For rooftop applications, ensure the roof is strong enough
to support the combined unit and support structural
weight. Refer to Table 1, p. 23 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.

Installation

Ductwork

Figure 16, p. 25 to Figure 18, p. 25 illustrate the supply and

return air openings as viewed from the rear of the unit.

Figure 16. 3-5 ton standard efficiency units & 3 ton high

efficiency units - Horizontal supply & return
air openings

Figure 17. 4-6 ton high efficiency units, 7½-8½

(Microchannel) high efficiency unit and 6-10
ton standard efficiency units - horizontal
supply & return air openings

Figure 19,p. 25 to Figure 21, p. 26 illustrate the supply and

return air openings in a downflow configuration.

Elbows with turning vanes or splitters are recommended
to minimize air noise due to turbulence and toreduce static
pressure.

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.

Figure 19. 3-5 ton standard efficiency units&3tonhigh

efficiency units - Down flow supply & return air
openings w/ through-the-base utilities

3 5/8”

92 MM

102 MM

610 MM

4”

24”

4 3/16”

106 MM

RETURN

14”

356 MM

23 1/2”

597 MM

9 1/4”

235 MM

406 MM

TBU CONDENSATE

THE BASE GAS

15 1/2”

394 MM

SUPPLY

16”

4 9/16”

116 MM

THROUGH

27 9/16”
701 MM

THROUGH
THE BASE

ELECTRICAL

4 7/8”

124 MM

5 1/16”

128 MM

9 15/16”
253 MM

2 13/16”

71 MM

3 11/16”

94 MM

6 1/2”

165 MM

Return

Supply

Figure 18. 10 ton high efficiency unit - horizontal supply

& return air openings

3 7/8”
98 MM

9 3/8”

238 MM

32 1/4”

Return

832 MM

16 3/4”

425 MM

27 5/8”
701 MM

4 3/4”

120 MM

4 1/4”
108 MM

32 1/4”
832 MM

Supply
19 1/4”

489 MM

3/4-14 NPT DIA. HOLE
CONDENSATE DRAIN

Figure 20. 4-6 ton high efficiency units, 7½-8½

(Microchannel) high efficiency units and 6-10
ton standard efficiency units - down flow
supply & return air openings w/ through-the­base utilities

RT-SVX21P-EN 25

Installation

838

Figure 21. 10 ton high efficiency unit - downflow supply

& return air openings w/ through-the-base

32 1/8”

816 MM

17 1/2”

444 MM

utilities

Return

27 5/8”

701 MM

9 7/8”

251 MM

17 1/2”

444 MM

Supply

THROUGH THE

BASE ELECTRICAL

THROUGH THE

BASE CONDENSATE

119 MM

33”

4 5/8”

MM

2 3/4”
71 MM

6 3/8”

163 MM

5 7/8”

149 MM

51 13/16”
1316 MM

42 3/16”

1072 MM

4”

102 MM

4 1/8”

104 MM

3 5/8”
92 MM

Roof Curb

Downflow

The roof curbs for these unitsconsists of a“full perimeter”

enclosure to support the unit just inside of the unit base
rail.The 10 ton high efficiency units contain a support base
alignment rail and will extend pastthe end ofthe roofcurb
as shown in figures below.

Before installing any roof curb, verify;

• It is the correct curb for the unit,

• It includes the necessary gaskets and hardware,

• The 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.

Step-by-step curb assembly and installation instructions
ship with each accessory roof curb kit. Follow the
instructions carefully to assure proper fit-up whenthe unit
is set into place.

Note: To assure proper condensate flow during

operation, as well as proper operation of the
condensate overflow switch (if equipped), 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 installingthe Supply Air and Return

Air ductwork joining the roof curb are included in the curb

instruction booklet. Curb ductwork must befabricated 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.

Figure 22. View for base to roof curb alignment

YHC120E on 50" x 84" roof curb

Base Alignment Bracket

Figure 23. View for base to roof curb alignment

YHC120E on 60" x 84" roof curb

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
combustible materials catching on fire. 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.

26 RT-SVX21P-EN

If a Curb Accessory Kit is not used:

• The ductwork can be attached directly to the factory­provided flanges around the unit’s supply and return
air openings. Be sure to use flexible duct connections
at the unit.

Installation

• 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

WARNING

Heavy Objects!

Ensure that all the lifting equipment used is properly
rated for the weight of the unit being lifted. Each of the
cables (chains or slings), hooks, and shackles 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 could cause
equipment or property damage. Failure to follow
instructions above or properly lift unit could result in
unit dropping and possibly crushing operator/
technician which could result in death or serious injury.

A Rigging illustration and Center-of-Gravity dimensional

data table is shown in Figure 15, p. 23. Refer to the typical
unit operating weights table before proceeding.

1. Remove all drill screws fastening wood protection to
metal base rail. Remove all screws securing wooden
protection to wooden top crate.

2. Remove WoodenTop Crate.

Figure 24. Fork pockets - all units except 10 ton high

efficiency units

Figure 25. Fork pockets - 10 ton high efficiency unit

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 unit dropping and
possibly crushing operator/technician which could
result in death or serious injury and possible equipment
or property-only damage.

3. Rig the unit as shown in Figure 15, p. 23. 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 15, p. 23,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.

NOTICE

6. Lift the unit enough to allow the removal of base fork
pocket protection components as shown in the
following figures.

7. When 10 ton high efficiency units are installed on
smaller existing roof curb (50"x 84") for replacement
applications, do not remove alignment bracket.This
bracket helps assure proper alignment of duct
openings.

8. 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 isrequired in the installationprocess. 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.

RT-SVX21P-EN 27

Installation

• Verify correct model, options and voltage from unit
nameplate.

• Verify that the installation location of the unit will
provide the required clearance for proper operation.

• Assembleand 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 istight and without buckles or
cracks.

• Install and connect a condensate drain line to the
evaporator drain connection.

Note: Condensate Overflow Switch (if equipped) will not

work if unit is not leveled properly.

Factory Installed Economizer

• Ensure the economizer has been pulled out into the
operating position. Refer to the economizer
installation guide for proper position and setup.

• Install all access panels.

Temperature Limit Switch Usage for Gas

Heat Units

Units are factory shipped in the down flow discharge
configuration but can be field converted to a horizontal
discharge configuration. Some, but not all units require a
differentTCO1 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:YSC036E**(M,Y),
YSC036E**(H,Z),YSC048E**(H,Z),
YSC048E**(M,Y) belt drive ID motor,
YSC060E**(H,Z) direct drive ID motor,
YHC047E**(L,X),YHC048E/F**(L,X) direct drive ID

motor,YHC060E/F**(L,X) belt drive ID,
YHC036E**(M,Y),YHC037E**(M,Y),YHC048E/

F**(M,Y),YHC060E/F**(M,Y) direct drive ID motor,
YHC036E**(H,Z),YHC048E/F**(H,Z) belt drive ID

motor,YHC060E/F**(H,Z), YSC072F**(H,Z),
YSC090F**(L,X),YSC092F**(H,Z),
YSC102F**(H,Z),YSC120F**(L,X),
YSC120F**(H,Z),YHC092F**(M,Y),
YHC102F**(M,Y),YHC120E**(H,Z).

If any of the aforementioned unitsare installed in thedown
flow discharge configuration, remove the additionalTCO1
limit switch from the combustion blower motor and
discard.

BD= Belt drive ID motor

DD= Direct drive ID motor

Table 3. TC01 tripping values

Unit Model (Std.

Eff.)

YSC036E**(L,X)-DD 180F YHC036E**(L,X)-DD 180F YHC037**(L,X) 190F
YSC036E**(L,X)-BD 170F YHC036E**(L,X)-BD 170F YHC037**(M,Y) 170F / 220F

YSC036E**(M,Y)-DD 170F / 190F YHC036E**(M,Y)-DD 170F / 190F YHC037**(H,Z) 220F

YSC036E**(M,Y)-BD 180F / 190F YHC036E**(M,Y)-BD 180F / 190F YHC047**(L,X) 145F / 155F

YSC036E**(H,Z)-DD 170F / 190F YHC036E**(H,Z)-DD 170F / 190F YHC047**(M,Y) 170F

YSC036E**(H,Z)-BD 155F / 190F YHC036E**(H,Z)-BD 155F / 190F YHC047**(H,Z) 220F
YSC048E**(L,X)-DD 180F YHC048E/F**(L,X)-DD 145F / 155F YHC067**(L,X) 140F

YSC048E**(L,X)-BD 170F YHC048E/F**(L,X)-BD 155F YHC067**(M,Y) 170F

YSC048E**(H,Z)-DD 155F / 210F YHC048E/F**(M,Y)-DD 150F / 170F YHC067**(H,Z) 170F

YSC048E**(M,Y)-BD 170F / 190F YHC048E/F**(M,Y)-BD 170F / 180F

YSC048E**(M,Y)-DD 180F YHC048E/F**(H,Z)-DD 220F

YSC048E**(H,Z)-BD 155F / 200F YHC048E/F**(H,Z)-BD 220F / 260F

YSC060E**(L, X) 170 YHC060E/F**(L,X)-DD 140F
YSC060E**(M,Y) 170F YHC060E/F**(L,X)-BD 155F / 145F

YSC060E**(H,Z)-DD 170F / 200F YHC060E/F**(M,Y)-DD 145F / 170F

YSC060E**(H,Z)-BD 170F YHC060E/F**(M,Y)-BD 170F

YSC072F**(M,Y) 155F YHC060E/F**(H,Z)-DD 190F / 220F

continued on next page

TCO1 Tripping

Values - Downflow/

Horizontal

Unit Model - (High

Eff. - 15 SEER)

TCO1 Tripping

Values -Downflow/

Horizontal

Unit Model

(High Eff. - 17 Plus)

TCO1 Tripping

Values -Downflow/

Horizontal

28 RT-SVX21P-EN

Table 3. TC01 tripping values (continued)

Installation

Unit Model (Std.

Eff.)

YSC072F**(L,X) 170F YHC060E/F**(H,Z)-BD 220F / 230F
YSC072F**(H,Z) 145F / 155F YHC072E/F**(L,X) 200F
YSC090F**(L,X) 180F / 200F YHC072E/F**(M,Y) 190F

YSC090F**(M,Y) 155F YHC072E/F**(H,Z) 210F

YSC090F**(H,Z) 155F YHC092F**(L,X) 190F
YSC092F**(L,X) 225F YHC092F**(M,Y) 180F / 200F

YSC092F**(M,Y) 230F YHC092F**(H,Z) 200F

YSC092F**(H,Z) 220F /260F YHC102F**(L,X) 190F
YSC102F**(L,X) 225F YHC102F**(M,Y) 180/200F

YSC102F**(M,Y) 230F YHC102F**(H,Z) 200F

YSC102F**(H,Z) 200F / 260F YHC120E**(L,X) 135F
YSC120F**(L,X) 180F / 200F YHC120E**(M,Y) 170F

YSC120F**(M,Y) 200F YHC120E**(H,Z) 145F / 190F

YSC120F**(H,Z) 190F / 260F

TCO1 Tripping

Values - Downflow/

Horizontal

Unit Model - (High

Eff. - 15 SEER)

TCO1 Tripping

Values -Downflow/

Horizontal

Horizontal Discharge Conversion
(3 to 5Ton Units)

Note: 3 to 5 ton units supply cover to supply opening and

return cover to return opening.

Supplies needed by installer for conversion: 3 oz. tube of
high temperature RTV sealant. (500°F / 260°C: similar to
Dow Corning 736)

Important: Failure to use recommended sealant could

result in unit performance loss.

If a unit is to be converted to a horizontal discharge, the
following conversion must be performed:

1. Remove RETURN and SUPPLY duct covers.

2. Locate supply cover. Apply ¼ in. (6mm.) continuous
bead of 500°F RTV sealant to the flange as shown.

Figure 26. Duct cover

RTV Sealant

6. After completing installation of the duct covers for

TCO-1 Instructions

If the unit being installed is listed in the following list, the
limit controlTCO1 must be replaced with the extra limit
control shipped in the heater compartment. ReplaceTCO1
following the instructions in steps 1 through3 below. If the
unit being installed does not correspond to any in the
following list, skip steps 1 through 3 and go on to next step
in the installation process.

Unit Model Number

YSC036E**(M,Y),YSC036E**(H,Z),YSC048E**(H,Z),
YSC048E**(M,Y) belt drive ID motor,YSC060E**(H,Z)

direct drive ID motor,YHC047E**(L,X), YHC048E/F**(L,X)
direct drive ID motor,YHC060E/F**(L,X) belt drive ID
motor,YHC036E**(M,Y), YHC037E**(M,Y), YHC048E/

F**(M,Y),YHC060E/F**(M,Y) direct drive ID motor,
YHC036E**(H,Z),YHC048E/F**(H,Z) belt drive ID motor,
YHC060E/F**(H,Z).

Unit Model

(High Eff. - 17 Plus)

TCO1 Tripping

Values -Downflow/

Horizontal

engages with the 2 retaining clips on the duct flange.
Secure outward edge of the duct cover with two
screws.

horizontal discharge, proceed toTCO-1 instructions.

3. Position duct cover as shown, rotate 90 degrees to
allow entrance into supply opening.

4. Slide duct covers into duct openings until inward edge
of duct cover engages with the 2 retaining clips on the
duct flanges. Secure the outward edge of each duct
cover with 2 screws.

5. Slide RETURN DUCT COVER (insulation side up) into
supply opening until inward edge of duct cover

RT-SVX21P-EN 29

Installation

FLAME
ROLLOUT
LIMIT

LOCATION OF TCO1 LIMIT
FOR THE Y(S/H)C036E, YHC037E,
YSC048E, AND YSC060E UNITS

Figure 27. TCO1 location (YSC036E-YSC060E, YHC036E,

YHC037E)

LOCATION OF TCO1 LIMIT
FOR THE Y(S/H)C036E, YHC037E,
YSC048E, AND YSC060E UNITS

FLAME
ROLLOUT
LIMIT

WARNING

Hazardous Voltage!

Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized. Failure to disconnect power
before servicing could result in death or serious injury.

1. Remove the heat section access panel.

2. RemoveTCO1 from shipping location, attached to the
combustion blower.

3. Replace and discard the existingTCO1 originally
installed at the factory for down flow operation with
theTCO1 shipped attached to the combustion blower
for horizontal operation.

4. Replace heat section access panel.

Horizontal Discharge Conversion
(6 to 10 Ton Units)

Note: 6 to 10 ton units the supply cover to return opening

& return cover to supply opening.

Supplies Needed by Installer for Conversion: 3 oz. tube of
highTemperature RTV sealant (500°F / 260°C: Similar to
Dow Corning 736).

Important: Failure to use recommended sealant could

result in unit performance loss.

If a unit is to be converted to a Horizontal discharge, the
following conversion must be performed:

1. Remove RETURN and SUPPLY duct covers.

2. Place SUPPLY DUCT COVER over down-flow return
opening. (insulation side down)

3. Using self-drilling screws, (or screws removed from
duct cover), screw through dimples to attach DUCT
COVER to base.

Figure 28. Duct cover

Supply Duct Cover

Screw into 4
dimples on top
edge

4. On original RETURN DUCT COVER, apply ¼”(6mm.)
continuous bead of 500°F RTV sealant around flange
(opposite insulation side), as shown.

Figure 29. Duct cover

RTV Sealant

5. Slide RETURN DUCT COVER (insulation side up) into
supply opening until inward edge of duct cover
engages with the 2 retaining clips on the duct flange.
Secure outward edge of the duct cover with two
screws.

Note: If unit is equipped with Return Air Smoke Detector,

refer to field conversion instructions for horizontal
discharge before installing return air duct.

Note: If unit is equipped with Discharge Air Sensing

option refer to the following figure for proper tube
positioning based on unit tonnage.

Figure 30. For YSC120F*R and YHC092F, 102F models

Downow application

Horizontal application

30 RT-SVX21P-EN

6. After completing installation of the duct covers for
horizontal discharge, proceed toTCO-1 instructions.

Installation

T

Figure 31. Supply and return covers

Supply duct cover

Insulation side
down

Insulation side up

Return duct
cover

TCO1 Instructions

If the unit being installed is listed in the following list, the
limit controlTCO1 must be replaced with the extra limit
control shipped in the heater compartment. ReplaceTCO1
following the instructions in steps 1 through3 below. If the
unit being installed does not correspond to any in the
following list, skip steps1 through 3 and go on to next step
in the installation process.

Unit Model Number

YSC072F**(H,Z),YSC092F**(M,Y),YSC092F**(H,Z),
YSC102F**(M,Y),YSC102F**(H,Z),YSC120F**(L,X),
YSC120F**(H,Z),YSC090F**(L,X),YHC092F(M,Y),
YHC102F**(M,Y),YHC120E**(L,X), YHC120E**(H,Z).

Figure 32. TCO1 location (YHC120E)

CO1 limit is located above

the burner on the YHC120E models

Replace original factory installed TCO1
with optional TCO1 attached to blower
housing for field convertion to horizontal discharge

Return Air Smoke Detector

The factory installed Return Air Smoke Detector is

installed in the downflow discharge position. No
additional field setup is required.

If a unit is to be converted to horizontal discharge, the
following conversion must be performed:

1. If the unit has an economizer, it must be pulled out in
the operating position.

2. Remove the 3 screws from the mounting brackets.
Refer to downflow view for screws locations.

Figure 33. Downflow view

WARNING

Hazardous Voltage!

Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized. Failure to disconnect power
before servicing could result in death or serious injury.

1. Remove the heat section access panel.

2. RemoveTCO1 from shipping location, attached to the
combustion blower.

3. Replace and discard the existingTCO1 originally
installed at the factory for down flow operation with
theTCO1 shipped attached to the combustion blower
for horizontal operation.

4. Replace heat section access panel.

3. Lift the tube and bracket from the downflow duct
opening. Rotate the tube and bracket assembly 180
degrees ensuring that the holes on the copper sensing
tube face away from the unit and face the return air
ductwork. Refer Figure 34, p. 32 and Figure 35, p. 32
for screws location.

RT-SVX21P-EN 31

Installation

2

Figure 34. Horizontal view 1

Figure 35. Horizontal view 2

120F,YHC120E andYHC072F-102F units secure the tab
on left side to the indoor coil block off with one of the
screws removed in step 2 and secure the right side of
the bracket with one of the screws removed from the
access panel. Refer to Figure 35, p. 32.

5. Using the remaining 2 screws removed in step 2,
secure the bottom bracket. Refer to Figure 34, p. 32.

Note: Larger diameter holes on bottom bracket line up

with the dimples on the rear panel.The smaller
diameter holes line up with the screw holes in the
rear panel.

Main Electrical Power
Requirements

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 capacitors before
servicing could result in death or serious injury.

4

Note: Check to insure that the flexible tubing lies flat on

the base pan surface.

4. Slide the top bracket down the copper sensing tube.
ForYSC036E-060E, andYHC036-037E units insert the
tab on the left side into the slot on the indoor coil block
off and secure the right side of the bracket with one of
the 3 screws removed in step 2. Refer to Figure 34,

p. 32. ForYHC047E-067E,YHC048E/F-060E/F,YSC072F-

For additional information regarding the safe discharge
of capacitors, see PROD-SVB06A-EN

WARNING

Proper Field Wiring and Grounding
Required!

All field wiring MUST be performed by qualified

personnel. Improperly installed and grounded field
wiring poses FIRE and ELECTROCUTION hazards. To
avoid these hazards, you MUST follow requirements for
field wiring installation and grounding as described in
NEC and your local/state electrical codes. Failure to
follow code could result in death or serious injury.

Verify that the power supply complies with the unit

nameplate specifications.

• Inspect all control panel components; tighten any
loose connections.

• Connect properly sized and protected power supply
wiring to a field-supplied/installed disconnect switch
and to the main power terminal block(HTB1) in the unit
control panel.

• Install proper grounding wires to an earth ground.

32 RT-SVX21P-EN

Installation

Through-the-Base Gas

Installation

The gas supply line must extend 4⅝” above the base pan.

The “Through-the-Base Gas” kit is located in the Heat

Vestibule compartment.To gain access to the kit, remove

the Heat Compartment access panel.

1. Remove the pipe assembly strapped to the manifold.
Unscrew 90° elbow from 6½” nipple and slide rubber
grommet off of nipple.

2. Remove the plastic plug from the hole in the center
post and insert the grommet removed from
6½” pipe nipple.

3. Using pipe sealant, attach the 90° elbow to the gas
supply line.

4. Disconnect the 5" pipe nipple and union from the

“Through-the-Base Gas” kit assembly.

5. Using pipe sealant, attach the 6½” nipple and gas
shutoff assembly to the 90° elbow on the gas supply
line.

6. Using pipe sealant, attach the 5" pipe nipple and union
to the street el attached to the gas valve.

7. Connect 5" pipe nipple and union to 6½” nipple and
gas shutoff assembly.

Figure 36. Typical through-the-base gas installation

• All gas piping joints properly sealed.

• Gas piping leak checked with a soap solution. If piping
connections to the unitare complete, do not pressurize
piping in excess of 0.50 psig or 14" W.C. to prevent
component failure.

• Drip leg Installed in the gas piping near the unit.

• Minimum gas supply pressure should be 4.5" W.C.

• Maximum gas supply pressure must not exceed 14.0"

W.C.

• Manifold pressure for single stage heaters should be
set to 3.3" W.C.

• Manifold pressure for two stage heaters should be set
to 3.5" W.C. on HIGH FIRE and 1.8" W.C. on LOW FIRE.

• Flue Exhaust clear of any obstruction.

Condensate Drain Configuration

WARNING

Hazardous Voltage!

Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized. Failure to disconnect power
before servicing could result in death or serious injury.

An evaporator condensate drain connection is provided

on each unit. Refer to Figure 16, p. 25 and Figure 17, p. 25
for the appropriate drain location.

The condensate drain pan is factory installed to drain

condensate to thebackside of the unit.See Figure 16, p. 25
and Figure 17, p. 25. It can be converted to drain
condensate out the front side of the unit or through-the­base.

Requirements for Gas Heat

Note: The unit gas train and OptionalThrough-the-Base

Gas Shut-OffValve are rated at 1/2 PSIG maximum.

A pressure reducing regulator is recommended to

prevent this maximum from being exceeded.

These components must be isolated during field

gas piping test that exceed 1/2 PSIG. It is
recommended that the field piping be capped prior
to the unit gas train or OptionalThrough-the-Base
Gas Shut-Off Valve if present.

• Gas supply line properly sized and connected to the
unit gas train.

RT-SVX21P-EN 33

To convert drain condensate out the front of

unit:

1. Remove evaporator accesspanel and supplyair access
panels.

2. Remove the support panel that the condensate drain
pan exits through.

3. Slide the condensate drain pan out of the unit and
rotate 180°.

4. Slide the condensatedrain pan back into the unit, align
the drain with the grommeted opening in the rear
support panel and push until the coupling is seated in
the grommet.

5. Replace the front support panel by aligning the panel
with tabs in the raceway. Align the condensate drain
pan support in the grommeted hole as the panel is put
in place.

6. Replace evaporator access panel and supply air access
panels.

Installation

To convert drain condensate through-the base

of unit:

1. Remove evaporator accesspanel and supplyair access
panels.

2. Remove the support panel that the condensate drain
pan exits through.

3. Slide the condensate drain pan out of the unit.

4. Place on a level surface in the position it was removed
from the unit.

5. Remove the plug knockout in the bottom of the drain
pan to convert it to through-the-base drainage.

6. Plug the original condensate drain opening with a field
supplied 3/4” NPT plug.

7. Slide the condensate drain pan back into the unit, align
the drain support with the grommeted opening in the
rear support panel and push until the support is seated
in the grommet.

8. Replace the front support panel by aligning the panel
with tabs inthe raceway.Align the pluggedcondensate
drain pan coupling in the grommeted hole as the panel
is put in place.

9. Replace evaporator access panel and supply air access
panels.

A condensate trap must be installed at the unit due to the

drain connection being on the“negative pressure” side of
the fan. Install the P-Trap using the guidelines in Figure 37,

p. 34.

A condensate drain line must be connected to the P-Trap.

Pitch the drain lines at least 1/2 inch for every 10 feet of
horizontal run to assure proper condensate flow. Do not
allow the horizontal run to sag causing a possible double­trap condition which could result in condensate backup
due to “air lock”.

Figure 37. Condensate trap installation

38.1

Drain Pan Removal (Units with Condensate
Overflow Switch Option)

Before drain pan removal, the switch wire must be
disconnected from wire tie on panel and/or any tape
before drain pan can be removed.

Care must be taken so the wire does not catch on the
bottom of indoor coil or any protrusion.

Note: When reversing the drain pan, on some units, the

condensate overflow switch will need to be moved
to the second hole in its bracket to avoid contact
with headers or indoor coil.

Filter Installation

The quantity of filters is determined by unit size.Access to

the filters is obtained by removing the filter access panel.
Refer to the unit Service Facts (shipped with each unit) for
filter requirements.

Note: Do not operate the unit without filters.

Field Installed Power Wiring

WARNING

Proper Field Wiring and Grounding
Required!

All field wiring MUST be performed by qualified

personnel. Improperly installed and grounded field
wiring poses FIRE and ELECTROCUTION hazards. To
avoid these hazards, you MUST follow requirements for
field wiring installation and grounding as described in
NEC and your local/state electrical codes. Failure to
follow code could result in death or serious injury.

An overall dimensional layout forthe field installed wiring

entrance into the unit is illustrated in “Unit Dimensions,”

p. 15.To insure that the unit’s supply power wiring is

properly sized and installed, follow the following
guidelines.

Verify that the power supply available is compatible with

the unit’s nameplate ratings.The available supply power
must be within 10% of the rated voltage stamped on the
nameplate. Use only copper conductors to connect the
power supply to the unit.

34 RT-SVX21P-EN

NOTICE:

Use Copper Conductors Only!

Unit terminals are not designed to accept other types
of conductors. Failure to use copper conductors could
result in equipment damage.

Important: If the unit is not equipped with an optional

factory installed non-fused disconnect
switch or circuit breaker, a field supplied
disconnect switch must be installed at or

Installation

near the unit in accordance with the
National Electrical Code (NEC latest
edition).

Main Unit Power

WARNING

Proper Field Wiring and Grounding
Required!

All field wiring MUST be performed by qualified

personnel. Improperly installed and grounded field
wiring poses FIRE and ELECTROCUTION hazards. To
avoid these hazards, you MUST follow requirements for
field wiring installation and grounding as described in
NEC and your local/state electrical codes. Failure to
follow code could result in death or serious injury.

WARNING

Hazardous Voltage!

Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized. Failure to disconnect power
before servicing could result in death or serious injury.

4 sides after installation to prevent air leakage from
the building entering the electrical enclosures.

Note: Seal between wiring and conduit with Black Gasket

or weather proof sealer to prevent air leakage from
the building entering the electrical enclosures. Also
seal around conduit and wiring at all roof and curb
penetrations.

Figure 38. All units except 10 ton high efficiency units

Standard Wiring

1. Location ofthe applicableelectrical serviceentrance is
illustrated in “Unit Dimensions,” p. 15. Complete the
unit’s power wiring connections at Compressor
Contactor # 1 (CC1) inside the unit control panel. Refer
to the customer connection diagram that is shipped
with the unit for specific termination points

2. Provide proper grounding for the unit in accordance
with local and national codes.

Optional TBUE Wiring (Through-the-Base
Electrical Option)

1. Location of the applicable electrical service is
illustrated below. Refer to the customer connection
diagram that is shipped with the unit for specific
termination points.The termination points, depending
on the customer option selected would be a factory
mounted non-fused disconnect switch (UDC) or circuit
breaker (UCB). If neither a factory mounted non-fused
disconnect switch (UDC) or circuit breaker (UCB) was
factory mounted, field wiring connections should be
terminated in the controlbox at Compressor Contactor
# 1 (CC1).

2. Provide proper grounding for the unit in accordance
with local and national codes.

Note: Black Gasket is shipped from the factory and is

located in the literature ship-with bag in the control
box.Apply BlackGasket around conduit plate on all

Figure 39. 10 ton high efficiency units

SEAL BETWEEN
WIRING AND
CONDUIT WITH
WEATHER PROOF
SEALER TO PREVENT
AIR LEAKAGE

CONTROL WIRING
CONDUIT

BLACK GASKET

FIELD POWERED
CONVENIENCE OUTLET
CONDUIT

CONTROL WIRING
CONDUIT

RT-SVX21P-EN 35

Installation

Field-Installed Control Wiring

WARNING

Hazardous Voltage!

Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized. Failure to disconnect power
before servicing could result in death or serious injury.

WARNING

Proper Field Wiring and Grounding
Required!

All field wiring MUST be performed by qualified

personnel. Improperly installed and grounded field
wiring poses FIRE and ELECTROCUTION hazards. To
avoid these hazards, you MUST follow requirements for
field wiring installation and grounding as described in
NEC and your local/state electrical codes. Failure to
follow code could result in death or serious injury.

An overall layout of the various control options available

with the required number of conductors for each control
device is illustrated in Figure 36, p. 33.

Note: All field wiring must conform to NEC guidelines as

well as state and local codes.

Control PowerTransformer

The 24 volt controlpower transformers are to be used only

with the accessories called out in this manual.

Transformers rated greater than 50VA are equipped with

internal circuit breakers. If a circuit breaker trips, turn “Off”
all power to the unit before attempting to reset it.

WARNING

Hazardous Voltage!

Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized. Failure to disconnect power
before servicing could result in death or serious injury.

The transformer is located in the control panel.The circuit

breaker is located on the left side of the transformer and
can be reset by pressing in on the black reset button.

Controls Using 24 VAC

Before installing any connecting wiring, refer to “Unit

Dimensions,” p. 15 for the electrical access locations

provided on the unit and Table 4, p. 36 or Table 5, p. 36 for

AC conductor sizing guidelines, and;

1. Use copper conductors unless otherwise specified.

2. Ensure that the AC controlwiring between thecontrols
and the unit’s termination point does not exceed three
(3) ohms/conductor for the length of the run.

NOTICE:

Controls Using 24 VAC!

Resistance in excess of 3 ohms per conductor could
cause component failure due to insufficient AC voltage
supply.

Note: Be sure to check all loads and conductors for

grounds, shorts, and mis-wiring.

3. Do not run the AC low voltage wiring in the same
conduit with the high voltage power wiring.

4. Route low voltage wiring per illustrations on page 38.

Table 4. Electromechanical thermostat 24V AC

conductors with ReliaTel™

Distance from Unit to Control Recommended Wire Size

000 - 460 feet 18 gauge
000 - 140 m .75 mm2
461 - 732 feet 16 gauge
141 - 223 m 1.3 mm2
733 - 1000 feet 14 gauge
224 - 305 m 2.0 mm2

Table 5. Electromechanical thermostat 24V AC

conductors with electromechanical unit

Distance from Unit to Control Recommended Wire Size

0 - 30 feet 22 gauge
0 - 9.1 m .33 m2
31 - 50 feet 20 gauge

9.5 - 15.2 m .50m2
51 - 75 feet 18 gauge

15.5 - 22.9 m .75 m2
76 - 125 feet 16 gauge

23.1 - 38.1 m 1.3 m2
126 - 200 feet 14 gauge

38.4 - 60.9 m 2.0 m2

Controls using DC Analog Input/Outputs
(Standard Low Voltage Multi
conductor Wire)

Before installing any connecting wiring between the unit
and components utilizing a DC analog input\output signal,
refer to “Unit Dimensions,” p. 15 for the electrical access
locations provided on the unit.

• Table 6, p. 37 lists the conductor sizing guidelines that
must be followed when interconnecting the DC binary
output devices and the system components utilizing a
DC analog input/output signal to the unit.

36 RT-SVX21P-EN

Installation

Note: Resistance in excess of 2.5 ohms per conductor can

cause deviations in the accuracy of the controls.

Note: Ensure that the wiring between controls and the

unit’s termination point does not exceed two and a
half (2.5) ohms/conductor for the length of the run.

• Do not run the electrical wires transporting DC signals
in or around conduit housing high voltage wires.

• Route low voltage wiring per illustrations on page 38.

DC Conductors

Table 6. Zone sensor module wiring

Distance from Unit to Control Recommended Wire Size

0 - 150 feet 22 gauge
0 - 45.7 m .33 mm2
151 - 240 feet 20 gauge
46 - 73.1 m .50 mm2
241 -385 feet 18 gauge

73.5 - 117.3 m .75 mm2
386 - 610 feet 16 gauge

117.7 - 185.9 m 1.3 mm2
611 - 970 feet 14 gauge

186.2 - 295.7 m 2.0 mm2

Figure 41. ReliaTel™ conventional thermostat field

wiring diagrams

RTRM

Figure 42. ReliaTel™ options module

Figure 40. Typical field wiring diagrams for

electromechanical

Figure 43. ReliaTel™ relative humidity sensor

(dehumidification option)

RT-SVX21P-EN 37

Installation

Figure 44. ReliaTel™ humidistat (dehumidification

option)

Figure 45. Electromechanical control customer low voltage routing (all units except 10 ton high efficiency)

Figure 46. ReliaTel™ control customer low voltage routing (all units except 10 ton high efficiency)

38 RT-SVX21P-EN

Figure 47. ReliaTel™ (without TBUE) control customer wire routing (10 ton high efficiency)

Installation

Figure 48. ReliaTel™ (with TBUE) control customer wire routing (10 ton high efficiency)

RT-SVX21P-EN 39

Installation

Figure 49. Electromechanical (without TBUE) control customer wire routing (10 ton high efficiency)

Figure 50. Electromechanical (with TBUE) control customer wire routing (10 ton high efficiency)

40 RT-SVX21P-EN

Installation

Space Temperature Averaging
(ReliaTel™ Only)

Space temperature averaging is accomplished by wiring a
number of remote sensors in a series/parallel circuit.

Using the BAYSENS016* or BAYSENS077*, at least four
sensors are required to accomplish space temperature
averaging. See diagram below.

Figure 51. Examples

• Example #1 illustrates two series circuits with two
sensors in each circuit wired in parallel.The square of
any number of remote sensors is required.

• Example #2 illustrates three sensors squared in a
series/parallel circuit. Using BAYSENS077*, two
sensors are required to accomplish spacetemperature
averaging.

• Example #3 illustrates the circuit required for this
sensor. Table 7, p. 43 lists the temperature versus
resistance coefficient for all sensors.

Note: Wiring pin numbers are for reference only.There

are multiple smoke detector systems that could
have differently numbered pins. For correct wiring

RT-SVX21P-EN 41

details, please refer to the specific smoke detector
literature that accompanied this unit.

Installation

Figure 52. Typical field wiring diagrams for optional controls (ReliaTel™ only)

BAYSENS075*

BAYSENS106*

BAYSENS073* BAYSENS074*

BAYSENS108*

BAYSENS075*

BAYSENS110*

BAYSENS119*

BAYSENS075*
ASYSTAT669A
OPTIONAL REMOTE SENSOR

42 RT-SVX21P-EN

Installation

Table 7. Temperature vs. resistance

Temperature

Degrees F° Degrees C° Nominal Resistance

-20° -28.9° 170.1 K - Ohms

-15° -26.1° 143.5 K - Ohms

-10° -23.3° 121.4 K - Ohms

-5° -20.6° 103.0 K - Ohms
0° -17.8° 87.56 K - Ohms
5° -15.0° 74.65 K - Ohms

10° -12.2° 63.80 K - Ohms
15° -9.4° 54.66 K - Ohms
20° -6.7° 46.94 K - Ohms
25° -3.8° 40.40 K - Ohms
30° -1.1° 34.85 K - Ohms
35° 1.7° 30.18 K - Ohms
40° 4.4° 26.22 K - Ohms
45° 7.2° 22.85 K - Ohms
50° 10.0° 19.96 K - Ohms
55° 12.8° 17.47 K - Ohms
60° 15.6° 15.33 K - Ohms
65° 18.3° 13.49 K - Ohms
70° 21.1° 11.89 K - Ohms
75° 23.9° 10.50 K - Ohms
80° 26.7° 9.297 K - Ohms
85° 29.4° 8.247 K - Ohms
90° 32.2° 7.330 K - Ohms
95° 35.0° 6.528 K - Ohms

Table 9. Iron pipe size (SI) millimeters

Iron Pipe Size (SI) Millimeters

Length of Pipe

(Meters)

4.6 2.15 4.98 9.76 21.23 34.54

9.1 1.47 3.39 6.82 15.14 24.06

13.7 1.21 2.80 5.63 12.31 19.82

18.3 1.07 2.43 4.89 10.76 17.27

22.9 — 2.18 4.38 9.76 15.40

Note: Capacity of Pipe of Different Diameters and Lengths in Cu. Meter Per

Hr. with Pressure Drop of 74.6 Pa and Specific Gravity of 0.60.

15 mm

Pipe

20 mm

Pipe

25 mm

Pipe

32 mm

Pipe

40 mm

Pipe

Figure 53. Schematic diagram for field gas piping to

unit

Table 8. Sizing natural gas pipe mains and branches

Iron Pipe Size (IPS) Inches

½"

¾"

1"

Length of Pipe (Ft.)

15 76 176 345 750 1220
30 52 120 241 535 850
45 43 99 199 435 700
60 38 86 173 380 610
75 77 155 345 545

Note: Capacity of Pipe of Different Diameters and Lengths in Cu. Ft. Per Hr .

with Pressure Drop of 0.3" and Specific Gravity of 0.60

Pipe

Pipe

Pipe

Pipe

1¼"

1½"
Pipe

RT-SVX21P-EN 43

Pre-Start

Use the checklist provided below in conjunction with the

“General Unit Requirements” checklist to ensure that the

unit is properly installed and ready for operation.

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 capacitors before
servicing could result in death or serious injury.

For additional information regarding the safe discharge
of capacitors, see PROD-SVB06A-EN

Verify that the condenser airflow will be unobstructed.

WARNING

Rotating Components!

During installation, testing, servicing and
troubleshooting of this product it may be necessary to
work with live and exposed rotating components. Have
a qualified or licensed service individual who has been
properly trained in handling exposed rotating
components, perform these tasks. Failure to follow all
safety precautions could result in rotating components
cutting and slashing technician which could result in
death or serious injury.

• Verify that the condenser fan and indoor blower turn
freely without rubbing and are properly tightened on
the shafts.

• Check the supply fan belts for proper tension and the
fan bearings for sufficient lubrication. If the belts
require adjustment, or if the bearingsneed lubricating,
refer to the maintenance section of this manual for
instructions.

• Verify that acondensate trap is installed and the piping
is properly sized and pitched.

• Verify that the correct size and number of filters are in
place.

• Inspect the interior of the unit for tools and debris and
install all panels in preparation for starting the unit.

Voltage Imbalance

Three phase electrical power to the unit must meet

stringent requirements for the unit to operate properly.

Measure each leg (phase-to-phase) of the power supply.
Eachreading must fallwithin the utilizationrange stamped
on the unit nameplate. If any of the readings do not fall

within the proper tolerances, notify the power company to
correct this situation before operating the unit.

Excessive three phase voltage imbalance between phases
will cause motors to overheat and eventually fail.The
maximum allowable voltage imbalance is 2%. Measure
and record the voltage between phases 1, 2, and 3 and
calculate the amount of imbalance as follows:

% Voltage Imbalance=

AV (Average Voltage)=

V1, V2, V3 = Line Voltage Readings

VD = Line Voltage reading that deviates the farthest from

the average voltage.

100 x AV - VD

AV

Volt 1 + Volt 2 + Volt 3

where;

3

Example: If the voltage readings of the supply power

measured 221, 230, and 227, the average volts would be:

221 + 230 + 227

3

VD (reading farthest from average) = 221

The percentage of imbalance equals:

100 x 226 - 221

226

The 2.2% imbalance in this example exceeds the

maximum allowable imbalance of 2.0%.This much
imbalance between phases can equal as much as a 20%
current imbalance with a resulting increase in motor
winding temperatures that will decrease motor life. If the
voltage imbalance is over 2%, notify the proper agencies
to correct the voltage problem before operating this
equipment.

= 226 Avg.

= 2.2%

Electrical Phasing (Three Phase
Motors)

The compressor motor(s) and the supply fan motor are

internally connected for the proper rotation when the
incoming power supply is phased as A, B, C.

Proper electrical supply phasing can be quickly
determined and corrected beforestarting the unit by using
an instrument such as an Associated Research Model 45
Phase Sequence Indicator and following the steps below:

• Turn the field supplied disconnect switch that provides
power to the main power terminal block or to the

“Line” side of the optionalfactory mounted disconnect

switch to the “Off” position.

• Connect the phase sequence indicator leads to the
terminal block or to the “Line” side of the optional
factory mounted disconnect switch as follows;

Black (phase A) to L1

Red (phase B) to L2

Yellow (phase C) to L3

44 RT-SVX21P-EN

Pre-Start

• Close the field supplied main power disconnect switch
or circuit protector switch that provides the supply
power to the unit.

Note: Upon closing main power disconnect and the unit

mounted disconnect switch or circuit breaker, the
phase monitor will verify proper phasing. If LED on
face of the monitor is red, correct supply power
fault.

WARNING

Live Electrical Components!

During installation, testing, servicing and
troubleshooting of this product, it may be necessary to
work with live electrical components. Have a qualified
licensed electrician or other individual who has been
properly trained in handling live electrical components
perform these tasks. Failure to follow all electrical safety
precautions when exposed to live electrical
components could result in death or serious injury.

To prevent injury or death from electrocution, it is the

responsibility of the technician to recognize this hazard
and use extreme care when performing service
procedures with the electrical power energized.

• Observe the ABC and CBA phaseindicator lights on the
face of the sequencer.The ABC indicator lightwill glow
if the phase is ABC. If the CBA indicator light glows,
open the disconnect switch or circuit protection switch
and reverse any two power wires.

• Restore the main electrical power and recheck the
phasing. If the phasing is correct, open the disconnect
switch or circuit protection switch and remove the
phase sequence indicator.

Compressor Crankcase Heaters (Optional)

Eachcompressor can be equipped with a crankcase heater
(on some units the crankcase heater comes standard).The
proper operation of the crankcase heater is important to
maintain an elevated compressor oil temperature during
the “Off” cycle to reduce oil foaming during compressor
starts. Oil foaming occurs when refrigerant condenses in
the compressor and mixes with the oil. In lower ambient
conditions, refrigerant migration to the compressor could
increase.

When the compressor starts, the sudden reduction in

crankcase pressure causes the liquid refrigerant to boil
rapidly causing the oil to foam.This condition could
damage compressor bearings due to reduced lubrication
and could cause compressor mechanical failures.

Before starting the unit in the “Cooling” mode, set the
system switch to the “Off” position and turn the main
power disconnect to the “On” position and allow the
crankcase heater to operate a minimum of 8 hours.

Before closing the main power disconnect switch, insure
that the “System” selection switch is in the “Off” position
and the “Fan” selection switch is in the “Auto” position.

Close the main power disconnect switch and the unit
mounted disconnect switch, if applicable.

Note: Upon closing main power disconnect and the unit

mounted disconnect switch or circuit breaker, the
phase monitor will verify proper phasing. If LED on
face of the monitor is red, correct supply power
fault.

WARNING

Live Electrical Components!

During installation, testing, servicing and
troubleshooting of this product, it may be necessary to
work with live electrical components. Have a qualified
licensed electrician or other individual who has been
properly trained in handling live electrical components
perform these tasks. Failure to follow all electrical
safety precautions when exposed to live electrical
components could result in death or serious injury.

To prevent injury or death from electrocution, it is the

responsibility of the technician to recognize this hazard
and use extreme care when performing service
procedures with the electrical power energized.

ReliaTel™ Controls

Upon power initialization, the RTRM performs self­diagnostic checks to insure that all internal controls are
functional. It also checks the configuration parameters
against the components connected to the system.The
Liteport LED located on the RTRM module is turned “On”
within one second of power-up if internal operation is
okay.

Use one of the following“Test” procedure to bypass some
time delays and to start the unit at the control panel. Each
step of unit operation can be activated individually by
temporarily shorting across the “Test”terminals for two to
three seconds.The Liteport LED located on the RTRM
module will blink when the test mode has been initiated.

The unit can be left in any “Test” step for up to one hour

before it will automatically terminate, or it can be
terminated by opening the main power disconnect switch.
Once the test mode has been terminated, the Liteport LED
will glow continuously and the unit will revert to the

“System” control.

RT-SVX21P-EN 45

Pre-Start

Table 10. Service test guide for component operation

Test

Step Mode Fan Econ

Fan On

1

Minimum

Ventilation

Economizer

2

Test Open

3

(e)

4

(e)

5

(e)

6

(e)

7

(e)

8

(a)The exhaust fan will turn on anytime the economizer damper position is equal to or greater than the exhaust fan setpoint.
(b)The PWM Output is in reference to the user selected maximum unit fan speed.
(c) Regardless of the Economizer Mode configuration, the unit will run the Supply Fan at the minimum speed during the Economizer step of the Service

Test.
(d)The condenser fans will operate any time a compressor is ‘On’ providing the outdoor air temperatures are within the operating values.
(e) Steps for optional accessories and non-applicable modes in unit will be skipped.
(f) Units with Enhanced Dehumidification only will not perform this step during Service Test.

Cool

Stage 1

Cool

Stage 2

Cool

Stage 3

Reheat On Minimum On On Off Off 33KΩ 100%

Heat

Stage 1

Heat

Stage 2

On Selectable Off Off Off Off

On Open Off Off Off Off 3.3K

On

On

On

On Minimum Off Off On Off 10K

On Minimum Off Off On On 15K

(a)

Minimum

Position

Setpoint 0%

Minimum

Position

Minimum

Position

Minimum

Position

Comp 1 Comp 2 Heat 1 Heat 2 Resistance

Off Off Off Off

2.2KΩ 50% low

Ω 50%

(d)

On

On

On

(d)

(d)

Off Off Off 4.7KΩ 82% low

(d)

On

On

(d)

Off Off 6.8KΩ 100%

Off Off 8.2KΩ 100% High

Ω 100% High

Ω 100% High

PWM

Output

Multi-Speed Fan

(b)

(c)

(f)

Output

High (2-step cooling)
Low (3-step cooling)

low

High

Test Modes

There are three methods in which the “Test” mode can be

cycled at LTB-Test 1 and LTB-Test 2.

1. Step Test Mode -This method initiates the different
components of the unit, one at a time, by temporarily
shorting across the two test terminals for two to three
seconds. For the initial start-up of the unit, this method
allows the technician to cycle a component “On” and
have up to one hour to complete the check.

2. ResistanceTest Mode -This method can be used for
start-up providing a decade boxfor variableresistance
outputs is available.This method initiates the different
components of the unit, one at a time, when a specific
resistance value is placed across the two test
terminals.The unit will remain inthe specific test mode
for approximately one hour even though the
resistance is left on the test terminals.

3. AutoTest Mode -This method is not recommended for
start-up due to the short timing between individual
component steps.This method initiates the different
components of the unit, one at a time, when a jumper
is installed across the test terminals.The unit will start
the first test step and change to the next step every 30
seconds.

At the end of the test mode, control of the unit will

automatically revert to the applied “System” control
method.

For unit test steps, test modes, and step resistance values
to cycle the various components, refer to Table 10, p. 46.

ReliaTel™ Controls

Upon power initialization, the Gas Ignition Module (IGN)
performs self-diagnostic checks to insure that all internal
controls are functional. It also checks the configuration
parameters against the components connected to the
system.The System LED located on the IGN module is
turned “On” within one second of power-up if internal
operation is okay.

46 RT-SVX21P-EN

Electromechanical Controls Test
Procedure

See unit schematic for correct wire numbers.

FanTest and Minimum Ventilation

Connect red thermostat wire (R) to black thermostat wire
(G).

Economizer Cooling

Connect a jumper wireacross OTS on Economizer Control
(ECA).

Connect red thermostat (R) wire to yellowthermostat wire
(Y1).

Cool 1

Connect red thermostat wire (R) to yellowthermostat wire
(Y1).

Cool 2

Connect red thermostat wire (R) to yellowthermostat wire
(Y2).

Heat 1

Connect red thermostat wire(R) to brown thermostat wire
(W1).

Pre-Start

Heat 2

Connect red thermostat wire(R) to brown thermostat wire
(W2).

RT-SVX21P-EN 47

Unit Start-Up

Verifying Proper Air Flow

WARNING

Live Electrical Components!

During installation, testing, servicing and
troubleshooting of this product, it may be necessary to
work with live electrical components. Have a qualified
licensed electrician or other individual who has been
properly trained in handling live electrical components
perform these tasks. Failure to follow all electrical safety
precautions when exposed to live electrical
components could result in death or serious injury.

Units with 5-Tap Direct Drive Indoor Fan

Much of the systems performance and reliability is closely
associated with, and dependent upon having the proper
airflow supplied both to the space that is being
conditioned and across the evaporator coil.

The indoor fan motor is factory wired to operate on speed

tap 1 in the cooling and heating mode for electric/electric
units. For Gas/Electric units, the motor is factory wired to
operate on speed tap 1 during cooling. For 3 & 4 ton Gas/
Electric units operating in heat mode, the minimum setting
isTap 4.

For these units, a separate tap terminal is provided to
change speeds automatically between heating and
cooling.The motor can be rewired for different speed
settings should the application require it. Refer to the
wiring diagram that shipped in the unit and the unit fan
performance tables in the Service Facts.

The indoor fan motors are specificallydesigned to operate

within the BHP parameters listed in the fan performance
tables of the unit Service Facts.

When verifying direct drive fan performance, the tables

must be used somewhat differently than those of belt
driven fans. Fan performance diagnostics can be easily
recognized when these tables are used correctly.

Before starting the SERVICETEST, set the minimum
position setpoint for the economizer to 0 percent using the
setpoint potentiometer located on the Economizer Control
(ECA), if applicable.

ReliaTel™ Control: Using the ServiceTest Guide in

Table 10, p. 46, momentarily jump across theTest 1 &Test

2 terminals on LTB1 one time to start the Minimum

Ventilation Test.

Electromechanical Control: Using the Service Test

Guide perform the proper test mode connections.

With the fan operating properly, determine the total

system external static pressure (inches w.c.) by the
following method (ReliaTel™/Electromechanical):

1. Measure the supply andreturn duct staticpressure and
sum the resulting absolute values,

2. Use the accessory pressure drop table in the Service
Facts, to calculate the total static pressure drop for all
of the accessories installed on the unit; i.e., curb,
economizer, etc.

Note: Accessory static pressure drop is based on desired

CFM and may not be actual static pressure drop.

3. Add the total accessory static pressure drop (step 2) to
the duct external static pressure (step 1).The sum of
these two values represents the total system external
static pressure.

Using the Fan PerformanceTables in the Service Facts,
look up the selected speed tap setting and match the
measured ESP to determine the approximate CFM.

If the required CFM is too low, (external static pressure is
high) do one or both of the following and repeat
procedure:

a. Relieve supply and/or return duct static.

b. Change indoor fan speed tap to a higher value

If the required CFM is too high, (external static pressure is
low), do one or both of the following and repeat
procedure:

a. Increase supply and/or return duct static.

b. Change indoor fan speed tap to a lower value.

Note: Minimum setting for units with Gas or Electric Heat

is320CFMperTon.For3&4TonGasHeat units
operating in heating mode the heat speed set
cannot be lower than Speed Set 4.

4. To stop the SERVICE TEST, turn the main power
disconnect switch to the “Off” position or proceed to
the next component start-up procedure.

Units with Belt Drive Indoor Fan

Much of the systems performance and reliability is closely
associated with, and dependent upon having the proper
airflow supplied both to the space that is being
conditioned and across the evaporator coil.

The indoor fan speed is changed by opening or closingthe

adjustable motor sheave.

Before starting the SERVICETEST, set the minimum
position setpoint for the economizer to 0 percent using the
setpoint potentiometer located onthe Economizer Control
(ECA), if applicable.

ReliaTel™ Control: Using the ServiceTest Guide in

Table 10, p. 46, momentarily jump across theTest 1 &Test

2 terminals on LTB1 one time to start the Minimum

Ventilation Test.

Electromechanical Control: Using the Service Test

Guide perform theproper test mode connections.Once the
supply fan has started, check for proper rotation.The

48 RT-SVX21P-EN

Unit Start-Up

direction of rotation is indicated by an arrow on the fan
housing.

With the fan operating properly, determine the total

system airflow (CFM) by (ReliaTel™/Electromechanical):

1. Measuring the actual RPM,

2. Measure the amperage at the supply fan contactor and
compare it with the fullload amp (FLA) rating stamped
on the motor nameplate.

a. Calculate the theoretical BHP using (Actual Motor

Amps/ Motor Nameplate Amps) X Motor HP.

b. Using the fanperformance tables in theunit Service

Facts, plot the actual RPM (step 1) and the BHP (step
2a) to obtain the operating CFM.

3. If the required CFM is too low, (externalstatic pressure
is high causing motor HP output to be below table
value),

a. Relieve supply and/or return duct static.

b. Change indoor fan speed and repeat steps 1 and 2.

• ToIncrease Fan RPM;Loosen the pulleyadjustment set
screw and turn sheave clockwise.

• To Decrease Fan RPM; Loosen the pulley adjustment
set screw and turn sheave counterclockwise.

• If the required CFM is too high, (external static
pressure is low causing motor HP output to be above
table value), change indoor fan speed and repeat steps
1 and 2.

• To stop the SERVICETEST, turn the main power
disconnect switch to the “Off” position or proceed to
the next component start-up procedure.

Economizer by disconnecting the 4 pin power connector
located at the base of the Economizer Control (ECA).

Using the ServiceTest Guide in Table 10, p. 60,
momentarily jump across theTest 1 &Test 2 terminals on
LTB1. Repeat process until ServiceTest Mode is at Cool 2
(2-Steps of Cooling Applications Only) or Cool 3 (3-Steps
of Cooling applications).The indoor motor shall be
operating @ 100%, to verify turn DA COOL_FAN SPD
potentiometer full clockwise, voltage should read ~7.5 Vdc
across harness test terminals.The Unit schematic
illustrates location for measuring the indoor motor speed
voltage.

Table 11. RPM table

Potentiometer

Voltage

1.25 217 4.50 1061

1.50 312 4.75 1126

1.75 362 5.00 1191

2.00 427 5.25 1253

2.25 479 5.50 1315

2.50 543 5.75 1374

2.75 605 6.00 1432

3.00 668 6.25 1487

3.25 732 6.50 1539

3.50 797 6.75 1588

3.75 863 7.00 1633

4.00 929 7.25 1675

4.25 995 7.50 1700

Note: Factory setting is 7.5V

Motor RPM

Potentiometer

Voltage

Motor RPM

Units with Direct Drive Indoor Fan ­Electromechanical Control

Much of the systems performance and reliability is closely
associated with, and dependent upon having the proper
airflow supplied both to the space that is being
conditioned and across the evaporator coil.Theindoor fan
speed is changed by adjusting the output voltage from the
MMC/ECM board tothe direct drive fan. Beforestarting the
SERVICETEST, set the minimum position setpoint for the
economizer to 0 percent using the setpoint potentiometer
located on the Economizer Control (ECA), if applicable.

Once the supply fan has started, determine the total
system airflow (CFM)

1. Measure the DC voltage across harness test terminals.
Using the fan rpm table shown above, determine RPM
correlated to measured voltage.

2. If the required CFM is too low, (external static pressure
is high causing motor HP output to be below table value),

a. Relieve supply and/or return duct static.

b. Change indoor fan speed and repeat steps 1 and 2.

• To Increase/Decrease Fan RPM turn DA COOL_FAN
SPD on the RTOM clockwise/counter-clockwise.

ReliaTel™ Units with Direct Drive Indoor
Fan (7½ - 8½Ton High Efficiency, 10Ton
Standard Efficiency)

Much of the systems performance and reliability is closely
associated with, and dependent upon having the proper
airflow supplied both to the space that is being
conditioned and across the evaporator coil.Theindoor fan
speed is changed by adjusting the voltage from the RTOM
Indoor Fan Speed output to the direct drive plenum fan. If
installed, before starting the SERVICETEST disable the

3. If the required CFM is too high, (external static pressure

is low causing motor HP output to be above table value),
change indoor fan speed and repeat steps 1 and 2.

• Stop the SERVICETEST, turn the main power
disconnect switch to the “Off” position and reconnect
Economizer 4-pin power connector if disconnected for
this procedure.

Proceed to the next component start-up procedure.

Electromechanical Control: Using the Service Test

Guide perform the proper test mode connections.

RT-SVX21P-EN 49

Unit Start-Up

Once the supply fan has started, determine the total
system airflow (CFM) by (ReliaTel™/Electromechanical):

1. Measure the DC voltage across pins Vt and com on the
MMC board or note the DC voltage shown on the ECM
board display. Using the fan rpm table shown above,
determine RPM correlated to measured voltage.

2. Measure the amperage at the supply fan contactor and
compare it with the full load amp (FLA) rating for the
evaporator motor stamped on the unit nameplate.

a. Calculate the theoretical BHP using (Actual Motor

Amps/Motor Nameplate Amps) X Motor HP.

b. Using the fanperformance tables in theunit Service

Facts, plot the actual RPM (step 1) and the BHP (step
2a) to obtain the operating CFM.

3. If the required CFM is too low, (externalstatic pressure
is high causing motor HP output to be below table
value),

a. Relieve supply and/or return duct static.

b. Change indoor fan speed and repeat steps 1 and 2.

• For MMC board:To increase or decrease Fan RPM push
and turn knob counter-clockwise or clockwise
respectively. Measure the DC voltage across pins Vt
and com on the MMC. Using the fan rpm table above,
determine RPM correlated to measured voltage.

• For ECM board:To Increase/Decrease Fan RPM:

a. Push and hold the SET button for 3 sec. Board will

display Motor 1 parameter name: Hi 1.

b. Slow push SET again to display the parameter’s

current value =7.50 volts.

c. Push on + or – button to adjust parameter todesired

value = XXX volts.

d. Push and hold SET button for 3 sec to “save” the

value. After save is complete, Hi 1 will show again.

e. After the voltage Hi 1 is successfully changed, the

display sequence will be:

MTR 1---> XXX -----> MTR2 -----> 0.00----->FST1---->ON/
OFF----->FST2------>ON/OFF------->EhEn-- --->ON/OFF

The motor will ramp up or down to adjust to the input

signal. Using the fan rpm table above, determine RPM
correlated to displayed voltage.

• If the required CFM is too high, (external static
pressure is low causing motor HP output to be above
table value), change indoor fan speed and repeat steps
1 and 2.

• To stop the SERVICETEST, turn the main power
disconnect switch to the “Off” position or proceed to
the next component start-up procedure.

Units with Constant CFM Direct Drive
Indoor Fan

Much of the systems performance and reliability is closely
associated with, and dependent upon having the proper

airflow supplied both to the space that is being
conditioned and across the evaporator coil.Theindoor fan
provides a constant CFM base on voltage output for the
potentiometer on the RTOM board. Before starting the
SERVICETEST, set the minimum position setpoint for the
economizer to 0% using the setpoint potentiometer
located on the Economizer Control (ECA), if applicable.

ReliaTel™ Control. Using the ServiceTest Guide in

Table 10, p. 46, momentarily jump across theTest 1 &Test

2 terminals on LTB1 one time to start the Minimum

Ventilation Test.

Once the supply fan has started, determine the total
system airflow (CFM) by:

1. Measure the DC voltage across pinsTP1 and ground
(screw on cornerof RTOMboard). Lookup desiredCFM
using the voltage CFM table shownon the accesspanel
label or in the unit Service Facts; record corresponding
voltage. Adjust potentiometer until output voltage
acrossTP1 and ground achieves desired CFM setpoint.

2. To increase voltage/CFM, turn potentiometer
clockwise.

3. To decrease voltage/CFM, turn potentiometer counter­clockwise.

Note: With ID fan access panel removed, fan will operate

at lower RPM due to the decrease in pressure. Once
panel is installed, RPM will increase.

17 Plus units with the constant CFM direct
drive indoor fan

Proper airflow is critical to unit operation. All 17 Plus
Precedent units (037, 047, and 067 units) use an indoor fan
that provides a constant CFM.There are two different
types of 17 Plus Precedent units: Single Zone VAV units
and Multi Speed units. Both types of units use the same
type of indoor motor and the same airflow adjustment
procedure.

To adjust airflow on a 17 Plus unit the Service Test mode

must be used for accurate results. Additionally, airflow
adjustments should be made in either “Cool Stage 2" or
any stage of heat becausethe fan is driven to its maximum
setting during thesestages. Only themaximum fan setting
requires adjustment, all other fan speeds follow the
maximum adjustment and do not require any adjustment.

Using the ServiceTest Guide in Table 10, p. 46, enter the
unit into either “Cool Stage 2" orany stage of heatby using
either the “StepTest Mode” or “ResistanceTest Mode”.

Once the unit is in either “Cool Stage 2" or any stage of
heat, system airflow (CFM) is determined by:

1. In the indoor fan compartment, locate the R136
potentiometer on the RTOM circuit board (also
designated “DA COOL - FAN SPD”). Also, locate the

TP1 test pin loop next to the R136 potentiometer.

2. Measure the DC Voltage across the test pinTP1 and
unit chassis ground. Compare DC voltage to the CFM

50 RT-SVX21P-EN

Unit Start-Up

chart shown in Table 12, p. 51. Table 12, p. 51 shows
what DC voltage corresponds to CFM per ton of unit
cooling.

Note: If 1200 cfm is required from a 3 ton unit

(037) the R136 potentiometer should be
adjusted so that the DC voltage measured
atTP1 to ground reads 1.65 volts DC.

3. To increase the TP1 voltage, turn the R136
potentiometer clockwise.

4. To decrease the TP1 voltage, turn the R136
potentiometer counter-clockwise.

Note: With the indoor fan access panel removed, the fan

will operate at a lower RPM because static pressure
is reduced with the door open. Once the panel is
returned the RPM of the indoor fan will increase.

Table 12. Cfm vs. vdc

PWM% value

70 <0.1 320
75 0.7 347
80 1.25 373
85 1.65 400
90 1.95 427
95 2.17 453

100 >2.4 480

Potentiometer

Voltage (vdc) CFM/Ton

Variable Air Volume Applications

(Traditional VAV)

Supply Air Temperature Control - Occupied
Cooling and Heating

The RTRM is designed to maintain a selectable supply air

temperature of 40°F to 90°F with a +/- 3.5°F deadband. In
cooling, if supply air temperature is more than 3.5 degrees
warmer than the selected temperature, a stage of cooling
will be turned “On” (if available).Then if the supply air
temperature is more than 3.5° cooler than the selected
temperature, a stage of cooling will be turned “Off”. At very
low airflows the unit may cycle stages “On” and “Off” to
maintain an average dischargeair temperature outsidethe
7° deadband. Duringlow load orlow airflow conditions the
actual temperature swing of the discharge air will likely be
greater.The RTRM utilizes a proportional and integral
control scheme with the integration occurring when the
supply air temperatureis outside the deadband.As long as
the supply air temperature is within the setpoint
deadband, the system is considered to be satisfied and no
staging up or down will occur.

Note: The RTRM is designed to maintain a selectable

supply air temperature of 40°F to 90°F with a +/-

3.5°F deadband. However, to reduce the risk of
evaporator coil freeze-up in Precedent andVoyager
Light Commercial applications, supply air
temperature should not be set below 50° F.

Supply Air Temperature Control with an
Economizer

The economizer is utilized to control the supply air cooling

at +1.5°F around the supplyair temperature setpoint range
of 40°F and 90°F providing the outside air conditions are
suitable.To reduce the risk of evaporator coil freeze-up
supply air temperature should not be set below 50° F.

While economizing, the mechanical cooling is disabled

until the economizer dampers have been fully open for
three minutes. If the economizer is disabled due to
unsuitable conditions, themechanical cooling willcycle as
though the unit had no economizer.

Note: The RTRM is designed to maintain a selectable

supply air temperature of 40°F to 90°F with a +/-

3.5°F deadband. However, to reduce the risk of
evaporator coil freeze-up in Precedent andVoyager
Light Commercial applications, supply air
temperature should not be set below 50°F.

VHR Relay Output

During unoccupied mode, daytime warm-up (DWU),
morning warm-up (MWU) and heating mode the Supply
Fan will operate at 100% of user set maximum airflow. All

VAV boxes must be opened through an ICS program or by

the VHR wired to the VAV boxes. The RTRM will delay
100% fan operation approximately 6.5 minutes when
switching from occupied cooling mode to a heating mode.

Zone Temperature Control without a Night

Setback Panel or ICS - Unoccupied Cooling

When a field supplied occupied/unoccupied switching

device is connectedbetween RTRM J6-11 andRTRM J6-12,
both the economizer and the mechanical cooling will be
disabled.

Zone Temperature Control without a Night

Setback Panel or ICS - Unoccupied Heating

When a field supplied occupied/unoccupied switching

device is connected between RTRM J6-11 and J6-12 and
DWU is enabled,the zone temperature will be controlledat
10°F below the Morning Warm-up setpoint, but not less
than 50°F, by cycling one or two stages of either gas or
electric heat, whichever is applicable.

MorningWarm-up (MWU) Control

MorningWarm-up is activated if the zone temperature isat
least 1.5°F below the MWU setpoint whenever the system
switches from Unoccupied to Occupied status.The MWU
setpoint may be set from the unit mounted potentiometer
or a remotely mounted potentiometer.The setpoint
ranges are from 50°F to 90°F. When the zone temperature
meets or exceeds the MWU setpoint, the unit willswitch to
the “Cooling” mode.The economizer will be held closed
during the morning warm-up cycle.

RT-SVX21P-EN 51

Unit Start-Up

DaytimeWarm-up (DWU) Control

Daytime Warm-up is applicable during occupied status
and when the zone temperature is below the initiation
temperature. It can be activated or deactivated through
ICS or anight setback zone sensor. If ICSor a night setback
zone sensor is not utilized, DWU can be activated by
setting the DWU enable DIP switch (RTAM) to ON and
supplying a valid morning warm-up setpoint.

The unit is shipped with a Morning Warm-up setpoint

configured and the DaytimeWarm-up function is activated
(switch on). Opening the DWU enable switch will disable
this function.

If the system control islocal, the DWUinitiation setpointis
3°F below the MorningWarm-up setpoint.The termination
setpoint is equal to the Morning Warm-up setpoint.

If the system control is remote (Tracer™), the DWU
setpoint is equal to theTracer Occupied heating setpoint.

The initiation and termination setpoints are selectable

setpoints designated byTracer.

When the zone temperature meets or exceeds the

termination setpoint while the unit is in an Occupied,

“Auto” Mode or switched to the “Cooling” Mode, the unit

will revert to the cooling operation.

If an Occupied “Heating” Mode is selected, the unit will
only function within the DWU perimeters until the system

is switched from the “Heat” Mode or enters an
Unoccupied status.

Note: When a LCI is installed on a VAV unit, the MWU

setpoint located on the RTAM board is ignored.The
MWU and DWU setpoints come from the higher
priority LCI-R DAC.

Supply Duct Static Pressure Control

The supply duct static pressure is measured by a

transducer with a 0.25 to 2.125 Vdc proportional output
which corresponds to an adjustable supply duct static
pressure of 0.3" w.c. to 2.5" w.c. respectively with a
deadband adjustment range from 0.2" w.c. to 1.0" w.c.The
setpoint is adjustable on the RTAM Static Pressure
Setpoint potentiometer or through ICS.

Traditional VAV Standalone Operation

If a traditional VAV unit is required to operate without ICS,
BAS or other “front end” controller, a jumper must be
placed between J6-2 and J6-4 of the RTRM to allow local
standalone control.

Example:

Supply Duct Static setpoint = 2.0" w.c. (RTAM)

Deadband = 0.2" w.c. (RTAM)

Duct Static Control Range = 1.9" w.c. to 2.1" w.c.

Figure 54. Transducer voltage output vs. pressure input

Supply AirTemperature Reset

The supply air temperature can be reset by using one of

four DIP switch configurations onthe RTAM orthrough ICS
when a valid supply air reset setpoint with a supply air
reset amount is given. A selectable reset amount of 0° F to
20°F via RTAMpotentiometer orICS is permissiblefor each
type of reset.

The amount of change applied to the supply air

temperature setpoint depends on how far the return air,
zone, or outdoor air temperature falls below the reset
temperature setpoint. If the return air, zone, or outdoor air
temperature is equal to or greater than the reset
temperature setpoint, the amount of change is zero.

If the return air, or zone temperature falls 3°F below the
reset temperature setpoint, the amount of reset applied to
the supply air temperature will equal the maximum
amount of reset selected.

If the outdoor air temperature falls 20°F below the reset
temperature setpoint, the amount of reset applied to the
supply air temperaturewill equal the maximum amount of
reset selected.The four DIP switch configurations are as
follows:

1. None - When RTAM DIP Switch #3 and #4 are in the
“Off” position, no reset will be allowed.

2. Reset based on Return AirTemperature - When RTAM

DIP Switch #3 is “Off” and Switch #4 is “On”,a
selectable supply air reset setpoint of 50°F to 90°F via
a unit mounted potentiometer orTracer™ is
permissible.

3. Reset based on ZoneTemperature - When RTAM DIP

Switch #3 is “On” and Switch #4 is “Off”, a selectable
supply air reset setpoint of 50°F to 90°F via RTAM
potentiometer orTracer is permissible.

52 RT-SVX21P-EN

Unit Start-Up

4. Reset based on Outdoor AirTemperature -When DIP
Switch #3 and #4 are“On”, a selectable supply air reset
setpoint of 0°F to 100°F via RTAM potentiometer or

Tracer is permissible.

Return Air Smoke Detector

The return air smoke detector is designed to shut off the

unit if smoke is sensed in the return air stream. Sampling
the airflow entering the unit at the return air opening
performs this function.

In order for the smoke detector to properly sense smoke in
the return airstream, the airvelocity entering theunit must
be between 500 and 4000 feet per minute. Equipment
covered in thismanual will developan 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 airflowvelocity that fallswithin
the required 500 to 4000 feet per minute range. For these
models, the design airflow shall be greater than or equal
to the minimum CFM specified in the table provided
below. Failure to follow these instructions will prevent the
smoke detector from performing its design function.

Economizer Start-Up

WARNING

Live Electrical Components!

During installation, testing, servicing and
troubleshooting of this product, it may be necessary to
work with live electrical components. Have a qualified
licensed electrician or other individual who has been
properly trained in handling live electrical components
perform these tasks. Failure to follow all electrical
safety precautions when exposed to live electrical
components could result in death or serious injury.

Minimum Position Setting for 17 Plus, 7.5-10

Ton with Multi-Speed, or Single Zone VAV

1. Apply power to the unit

2. Using the ServiceTest Guide on unit access panel,
momentarily jump across theTest 1 &Test 2 terminals
on LTB1 one time to start indoor fan.

3. Turn the MIN POS - DCV potentiometer on the RTEM
clockwise to open or counter-clockwise to close.The
damper will open to this setting for low speed fan
operation. When adjusting minimum position, the
damper may move to the new setting in several small
steps.Wait at least 15 seconds for the damper to settle
at the new position. Range of damper for this setting is
0-100%.

4. Momentarily jump across theTest 1 &Test 2 terminals
on LTB1, to cycle through test modes to Cool 1.

5. Turn the DCV SETPOINT - LL potentiometer on the
RTEM clockwise to open or counter-clockwise to close.

This will set the minimum damper position at an

intermediate point of fan operation range of damper
for this setting is 0-75%.

6. Momentarily jump across theTest 1 &Test 2 terminals
on LTB1, to cycle through test modes to Cool 2.

7. Turn the MIN POS - DESIGN potentiometer on the
RTEM clockwise to open or counter-clockwise to close.

This will set the minimum damper position at

maximum fan speed. Range of damper for this setting
is 0-50%.

8. The economizer minimum damper position for all fan
speeds is complete.The RTEM will control minimum
damper position along an imaginary line between the
3 damper minimum positions based on fan speed.
Note:The RTEM will limit intermediate minimum
damper position to ensure proper ventilation based
upon the low fan speed minimum damper position set
in Step 3.

9. Replace the filter access panel.The damper will close
when the blower circuit is de-energized.

WARNING

Live Electrical Components!

During installation, testing, servicing and
troubleshooting of this product, it may be necessary to
work with live electrical components. Have a qualified
licensed electrician or other individual who has been
properly trained in handling live electrical components
perform these tasks. Failure to follow all electrical
safety precautions when exposed to live electrical
components could result in death or serious injury.

ReliaTel™ Control: Using the ServiceTest Guide in

Table 10, p. 46, momentarily jump across theTest 1 &Test

2 terminals on LTB1 one time to start the Minimum

Ventilation Test.

Electromechanical Control: Using the Service Test

Guide perform the proper test mode connections.

1. Set the minimum position setpoint for the economizer
to the required percentage of minimum ventilation
using the setpoint potentiometer located on the
Economizer Control (ECA).

The economizer will drive to its minimum position

setpoint, exhaust fans (if applicable) may start at
random, and the supply fan will start when the
SERVICETEST is initiated.

RT-SVX21P-EN 53

Unit Start-Up

WARNING

Rotating Components!

During installation, testing, servicing and
troubleshooting of this product it may be necessary to
work with live and exposed rotating components. Have
a qualified or licensed service individual who has been
properly trained in handling exposed rotating
components, perform these tasks. Failure to follow all
safety precautions could result in rotating components
cutting and slashing technician which could result in
death or serious injury.

The Exhaust Fan will start anytime the economizer

damper position is equal to orgreater than the exhaust
fan setpoint.

2. Verify that the dampers stroked to the minimum
position.

ReliaTel™ Control:

Momentarily jump across theTest 1 &Test 2 terminals
on LTB1 one additional time if continuing from
previous component start-up or until the desired start­up component test is started.

Electromechanical Control:

Using the ServiceTest Guide perform the proper test
mode connections.

3. Verify that the dampers stroked to the full open
position.

4. To stop the SERVICE TEST, turn the main power
disconnect switch to the “Off” position or proceed to
the next component start-up procedure. Remove
electromechanical test mode connections (if
applicable).

leads (at the compressorTerminal block) to check
the internal phasing. If the compressor runs
backwardfor an extendedperiod (15 to 30minutes),
the motor winding can overheat and cause the
motor winding thermostat to open.

2. After the compressor and condenser fan have started
and operated for approximately 30 minutes, observe
the operating pressures. Compare the operating
pressures to the operating pressure curve in the
Service Facts.

3. Check system superheat. Follow the instruction listed
on the superheat charging curve in the Service Facts.

Superheat should be within ±5F ofthe superheatchart
value.

4. Repeat steps 1 through 4 for each refrigerant circuit.

5. To stop the SERVICE TEST, turn the main power
disconnect switch to the “Off” position or proceed to
the next component start-up procedure. Remove
electromechanical test mode connections (if
applicable).

Dehumidification Option

WARNING

Live Electrical Components!

During installation, testing, servicing and
troubleshooting of this product, it may be necessary to
work with live electrical components. Have a qualified
licensed electrician or other individual who has been
properly trained in handling live electrical components
perform these tasks. Failure to follow all electrical
safety precautions when exposed to live electrical
components could result in death or serious injury.

Compressor Start-Up

1. Attach a set of service gauges onto the suction and
discharge gauge ports for each circuit. Refer to the
refrigerant circuit illustration in the Service Facts.

ReliaTel™ Control:

Momentarily jump across theTest 1 &Test 2 terminals
on LTB1 one additional time if continuing from
previous component start-up or until the desired start­up componentTest is started.

Electromechanical Control:

Using the ServiceTest Guide perform the proper test
mode connections.

Scroll Compressors

a. Once each compressor has started, verify that the

rotation is correct. If a scroll compressor is rotating
backwards, it will not pump and a loud rattling
sound can be observed.

b. If the electrical phasing is correct, before

condemning a compressor, interchange any two

54 RT-SVX21P-EN

Momentarily jump across theTest 1 andTest 2 terminals of
the LTB1 until the unit enters test mode 7 (See Table 10,

p. 46). Once the unit is in the reheat test mode, verify that

the 3 way valve has shifted to the reheat position and that
the supply temperature rises 10°F more than when in
cooling mode stage 2.

Monitor the suction pressure for 15 minutes.The suction
pressure should remain within 5 psi of normal cooling
operation.

Gas Heat Units

Open the main disconnect switch to shut the unit off and
to reset the RTRM.

ReliaTel™ Control: Follow theTest Guide in Table 10,

p. 46 to start the unit in the heating mode. Momentarily

jump across theTest 1 & Test 2 terminals on LTB1 one
additional time if continuing from previous component
start-up or until the desired start-up componentTest is
started.

Electromechanical Control. Using the Service Test

Guide perform the proper test mode connections.

When starting the unit for the first time or servicing the

heaters, it is a good practice to start the heater with the
main gas supply turned “Off”.

Once the ignition system and components have been
checked, open the main power disconnect switch to reset
the unit.

Final System Setup

After completing all of the pre-start and start-up

procedures outlined in the previous sections (i.e.,
operating the unit in each of its Modes through all
available stages of cooling & heating), perform these final
checks before leaving the unit:

• Program the Night Setback (NSB) panel (if applicable)
for proper unoccupied operation. Refer to the
programming instructions for the specific panel.

• Verify that the Remote panel “System” selection
switch, “Fan” selection switch, and “Zone

Temperature” settings for automatic operation are

correct.

• Inspect the unit for misplaced tools, hardware, and
debris.

• Verify that all exterior panels including the control
panel doors and condenser grilles are secured in place.

• Close the main disconnect switch or circuit protector
switch that provides the supply power to the unit’s
terminal block or the unit mounted disconnect switch.

Unit Start-Up

RT-SVX21P-EN 55

Maintenance

WARNING

Hazardous Service Procedures!

The maintenance procedures recommended in this

section of the manual could result in exposure to
electrical, mechanical or other potential safety hazards.

Always refer to the safety warnings provided

throughout this manual concerning these procedures.
Unless specified otherwise, disconnect all electrical
power including remote disconnect and discharge all
energy storing devices such as capacitors before
servicing. Follow proper lockout/tagout procedures to
ensure the power can not be inadvertently energized.

When necessary to work with live electrical

components, have a qualified licensed electrician or
other individual who has been trained in handling live
electrical components perform these tasks. Failure to
follow all of the recommended safety warnings
provided, could result in death or serious injury.

Fan Belt Adjustment - Belt Drive
Units

WARNING

Live Electrical Components!

During installation, testing, servicing and
troubleshooting of this product, it may be necessary to
work with live electrical components. Have a qualified
licensed electrician or other individual who has been
properly trained in handling live electrical components
perform these tasks. Failure to follow all electrical
safety precautions when exposed to live electrical
components could result in death or serious injury.

WARNING

Rotating Components!

During installation, testing, servicing and
troubleshooting of this product it may be necessary to
work with live and exposed rotating components. Have
a qualified or licensed service individual who has been
properly trained in handling exposed rotating
components, perform these tasks. Failure to follow all
safety precautions could result in rotating components
cutting and slashing technician which could result in
death or serious injury.

The fan belts must be inspected periodically to assure

proper unit operation.

Replacement is necessary if the belts appear frayed or
worn. Units with dual belts require a matched set of belts
to ensure equal belt length.

When removing or installing the new belts, do not stretch

them over the sheaves. Loosen the belts using the belt
tension adjustment bolts on the motor mounting base.

Once the new belts are installed, using a Browning or
Gates tension gauge (or equivalent) illustrated in

Figure 55, p. 56, adjust the belt tension as follows;

1. To determine the appropriate belt deflection;

a. Measure the center-to-center shaft distance (in

inches) between the fan and motor sheaves.

b. Divide the distance measured in Step 1a by 64; the

resulting value represents the amount of belt
deflection that corresponds to the proper belt
tension.

2. Set the large O-ring on the belt tension gauge at the
deflection value determined in Step 1b.

3. Set the small O-ring at zero on the force scale of the
gauge plunger.

4. Place the large end of the gauge at the center ofthe belt
span, then depress the gauge plunger until thelarge O­ring is even with the top of the next belt or even with
a straightedge placed across the fan and motor
sheaves. Refer to Figure 55, p. 56.

5. Remove the belt tension gauge.The small O-ring now
indicates a number other than zero on the plunger’s
force scale.This number represents the force (in
pounds) required to give the needed deflection.

6. Compare the “force” scale reading (Step 5) with the
appropriate“force” value listed in Table 13, p. 57. If the

“force” reading is outside the range, readjust the belt

tension.

Note: Actual belt deflection “force” must not exceed the

maximum “force” value shown in Figure 55, p. 56.

7. Recheck the belt tension at least twice during the first
2 to 3 days of operation. Belt tension may decrease
until the new belts are “run in”.

Figure 55. Belt tension gauge

56 RT-SVX21P-EN

Maintenance

Table 13. Belt tension measurement and deflection

Deflection Force (Lbs.)

Belts
Cross
Section

A

B

Small
P.D
Range

3.0 - 3.6 3 4 1/2 3 7/8 5 1/2 3 1/4 4

3.8 - 4.8 3 1/2 5 4 1/2 6 1/4 3 3/4 4 3/4

5.0 - 7.0 4 5 1/2 5 6 7/8 4 1/4 5 1/4

3.4 - 4.2 4 5 1/2 5 3/4 8 4 1/2 5 1/2

4.4 - 5.6 5 1/8 7 1/8 6 1/2 9 1/8 5 3/4 7 1/4

5.8 - 8.8 6 3/8 8 3/4 7 3/8 10 1/8 7 8 3/4

Super
Gripbelts Gripnotch

Min. Max. Min. Max. Min. Max

Steel Cable
Gripbelts

Monthly Maintenance

WARNING

Hazardous Voltage!

Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized. Failure to disconnect power
before servicing could result in death or serious injury.

Before completing the following checks, turn the unit OFF
and lock the main power disconnect switch open.

Filters

Inspect the return air filters. Clean or replace them if
necessary. If included, leave filter removal tool in unit.
Refer to the unit Service Facts for filter information.

Return Air Smoke Detector Maintenance

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.

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.

Condensate Overflow Switch

During maintenance, the switch float (black ring) must be
checked to ensure free movement up and down.

Cooling Season

• Check the unit’s drain pans and condensate piping to
ensure that there are no blockages.

• Inspect the evaporator and condenser coils for dirt,
bent fins, etc. If the coils appear dirty, clean them
according to the instructions described in “Coil
Cleaning” later in this section.

• Manually rotate the condenser fan(s) to ensure free
movement and check motor bearings for wear. Verify
that all of the fan mounting hardware is tight.

• Inspect the F/A-R/A damper hinges and pins to ensure
that all moving parts are securely mounted. Keep the
blades clean as necessary.

• Verify that all damper linkages move freely; lubricate
with white grease, if necessary.

• Check supply fan motor bearings; repair or replace the
motor as necessary.

• Check the fan shaft bearings for wear. Replace the
bearings as necessary.

• Check the supply fan belt. If the belt is frayed or worn,
replace it. Refer to the “Fan Belt Adjustment” section
for belt replacement and adjustments.

• Verify that all wire terminal connections are tight.

• Remove any corrosion present onthe exterior surfaces
of the unit and repaint these areas.

• Generally inspect the unit for unusual conditions (e.g.,
loose access panels, leaking piping connections, etc.)

• Make sure that all retaining screws are reinstalled in
the unit access panels once these checks are complete.

• With the unit running, check and record the: ambient
temperature; compressor suction and discharge
pressures (each circuit); superheat (each circuit);

• Record this data on an “operator’s maintenance log”
like the one shown in Table 14, p. 59. If the operating
pressures indicate a refrigerant shortage, measure the
system superheat. For guidelines, refer to the

“Compressor Start-Up” section.

Important: Do not release refrigerant to the

atmosphere! If adding or removing
refrigerant is required, the service
technician must comply with all federal,
state and local laws.

Heating Season

• Inspect the unit’s air filters. If necessary, clean or
replace them.

• Check supply fan motor bearings; repair or replace the
motor as necessary.

• Inspect both the main unit control panel and heat
section control box for loose electrical components
and terminal connections, as well as damaged wire
insulation. Make any necessary repairs.

RT-SVX21P-EN 57

Maintenance

• Clean burner area, verify gas heat system operates
properly.

Coil Cleaning

Regular coil maintenance, including annual cleaning,
enhances the unit’s operating efficiency by minimizing:
compressor head pressure and amperage draw,
evaporator water carryover, fan brake horsepower due to
increase static pressure losses, airflow reduction.

At least once each year, or more often if the unit is located

in a “dirty” environment, clean the evaporator and
condenser coils using the instructions outlined below. Be
sure to follow these instructions as closely as possible to
avoid damaging the coils.

Note: For units equipped with hail guards follow removal

procedure listed below.

Hail Guard Removal

• Unlatch hail guard.

• Pull the top ofthe hail guard outward until the fastener
studs are free of the retaining nuts.

• Lift the hail guard from the lower retaining bracket and
set aside.

Microchannel (MCHE) Coils

NOTICE:

Coil Damage!

DO NOT use any detergents with microchannel
condenser coils. Use pressurized water or air ONLY,
with pressure no greater than 600psi. Failure to do so
could result in coil damage.

For additional information regarding the proper
microchannel coil cleaning procedure, refer to RT­SVB83*-EN.

Due to the soft material and thin walls of the MCHE coils,
the traditional field maintenance method recommended
for RoundTube Plate Fin (RTPF) coils does not apply to
microchannel coils.

Moreover,chemical cleaners are a risk factorto MCHE due
to the material of the coil.The manufacturer does not
recommend the use of chemical cleaners to clean
microchannel coils. Using chemical cleaners could lead to
warranty claims being further evaluated for validity and
failure analysis.

The recommended cleaning method for microchannel

condenser coils is pressurized water or air with a non­pinpoint nozzle andan ECU of at least180 with pressureno
greater than 600 psi.To minimize the risk of coil damage,
approach the cleaning of thecoil withthe pressure washer
aimed perpendicular to the face ofthe coil during cleaning.

Note: For more details on Microchannel coil cleaning,

please refer to bulletin RT-SVB83*-EN.

Round Tube Plate Fin (RTPF) Coils

To clean refrigerant coils, use a soft brush and a sprayer

(either a garden pump-up typeor a high-pressure sprayer).

A high-quality detergent is also required; suggested

brands include “SPREX A.C.”, “OAKITE 161”, “OAKITE 166”
and “COILOX”. If the detergent selected is stronglyalkaline
(ph value exceeds 8.5), add an inhibitor.

WARNING

Hazardous Chemicals!

Coil cleaning agents can be either acidic or highly
alkaline and can burn severely if contact with skin
occurs. Handle chemical carefully and avoid contact
with skin. ALWAYS wear Personal Protective Equipment
(PPE) including goggles or face shield, chemical
resistant gloves, boots, apron or suit as required. For
personal safety refer to the cleaning agent
manufacturer’s Materials Safety Data Sheet and follow
all recommended safe handling practices. Failure to
follow all safety instructions could result in death or
serious injury.

1. Remove enough panels from the unit to gain access to
the coil.

2. Protect all electrical devices such as motors and
controllers from any over spray.

3. Straighten any bent coil fins with a fin comb.

WARNING

Hazardous Pressures!

Coils contain refrigerant under pressure.When cleaning
coils, maintain coil cleaning solution temperature
under 150°F to avoid excessive pressure in the coil.
Failure to follow these safety precautions could result
in coil bursting, which could result in death or serious
injury.

4. Mix the detergent with water according to the
manufacturer’s instructions. If desired, heat the
solution BUT DO NOT EXCEED 150ºF maximum to
improve its cleansing capability.

5. Pour the cleaning solution into the sprayer. If a high­pressure sprayer is used:

a. do not allow sprayer pressure to exceed 600 psi.

b. the minimum nozzle spray angle is 15 degrees.

c. maintain a minimum clearance of 6" between the

sprayer nozzle and the coil.

d. spray the solution perpendicular (at 90 degrees) to

the coil face.

6. Spray the leaving-airflow side of the coil first; then
spray the opposite side of the coil. Allow the cleaning
solution to stand on the coil for five minutes.

7. Rinse both sides of the coil with cool, clean water.

58 RT-SVX21P-EN

Maintenance

8. Inspect both sides of the coil; if it still appears to be
dirty, repeat Step 6 and Step 7.

9. Reinstall all of the components and panels removed in

Step 1 and any protective covers installed in Step 2.

Note: For units equipped with hail guards follow

reinstallation procedure listed below.

Hail Guard Reinstallation

10.To reinstall the hail guard, locate the bottom of the hail
guard in the lower bracket and secure it to the upper
unit bracket with the attached fasteners.

Note: Secure hail guard latches.

Figure 56. Hail guard

11. Restore the unit to its operational status and check
system operation.

Annual Maintenance

• Clean and repaint any corroded surface.

Final Process

For future reference, you may find it helpful to record the
unit data requested in the blanks provided.

Complete Model Number:

Unit Serial Number:

Wiring Diagram Numbers

(from unit control panel):

Connections:

Schematics:

Table 14. Sample maintenance log

Refrigerant Circuit #1 Refrigerant Circuit #2

Date

Current

Ambient

Temp. F/C

Compr.

Oil Level

- ok

- low

- ok

- low

- ok

- low

- ok\

- low

- ok

- low

Suct.

Press.

Psig/

kPa

Disch.
Press.

Psig/

kPa

Liquid
Press.

Psig/

kPa

Note: Check and record the data requested above each

month during the cooling season with the unit
running.

Super

-heat
F/C

Sub­cool.

F/C

Compr.

Oil

Level

- ok

- low

- ok

- low

- ok

- low

-- ok

- low

- ok

- low

Suct.

Press.

Psig/kPa

Disch.
Press.

Psig/

kPa

Liquid
Press.

Psig/

kPa

Super-

heat

F/C

Sub­cool.

F/C

RT-SVX21P-EN 59

Troubleshooting

WARNING

Hazardous Service Procedures!

The troubleshooting procedures recommended in this

section of the manual could result in exposure to
electrical, mechanical or other potential safety hazards.

Always refer to the safety warnings provided

throughout this manual concerning these procedures.
Unless specified otherwise, disconnect all electrical
power including remote disconnect and discharge all
energy storing devices such as capacitors before
servicing. Follow proper lockout/tagout procedures to
ensure the power can not be inadvertently energized.

When necessary to work with live electrical

components, have a qualified licensed electrician or
other individual who has been trained in handling live
electrical components perform these tasks. Failure to
follow all of the recommended safety warnings
provided, could result in death or serious injury.

ReliaTel™ Control

The RTRM has the ability to provide the service personnel

with some unitdiagnostics and system status information.

Before turning the main power disconnect switch “Off”,
follow the steps below to check the ReliaTel Refrigeration
Module (RTRM). All diagnostics & system status
information stored in theRTRM will be lost when the main
power is turned “Off”.

WARNING

Live Electrical Components!

During installation, testing, servicing and
troubleshooting of this product, it may be necessary to
work with live electrical components. Have a qualified
licensed electrician or other individual who has been
properly trained in handling live electrical components
perform these tasks. Failure to follow all electrical
safety precautions when exposed to live electrical
components could result in death or serious injury.

To prevent injury or death from electrocution, it is the

responsibility of the technician to recognize this hazard
and use extreme care when performing service
procedures with the electrical power energized.

1. Verify LED onface ofthe phase monitor is green.If LED
is red, correct supply power fault.

2. Verify that the Liteport LED on the RTRM is burning
continuously. If the LED is lit, go to Step 3.

3. If the LED is not lit, verify that 24 VAC is presence
between J1-1 and J1-2. If 24 VAC is present, proceed to

Step 4. If 24 VAC is not present, check the unit main

power supply, check transformer (TNS1). Proceed to
Step 4 if necessary.

4. Utilizing “Method 1” or “Method 2” in the “System
Status Diagnostic” section, check the following:

• System status

• Heating status

• Cooling status

If a system failure is indicated, proceed to Step 5.Ifno
failures are indicated, proceed to Step 6.

5. If a System failure is indicated, recheck Step 2and Step

3. If the LED is not lit in Step 2, and 24 VAC is present

in Step 3, the RTRM has failed. Replace the RTRM.

6. If no failures are indicated, use one of theTEST mode
procedures described in the “Unit Start-Up” section to
start the unit.This procedure will allow you to check all
of the RTRM outputs, and all of the external controls
(relays, contactors, etc.) that the RTRM outputs
energize, for each respective mode. Proceed to Step 7.

7. Step the system through all of the available modes,
and verify operation of all outputs, controls, and
modes. If a problem inoperation is noted in any mode,
you may leave the system in that mode for up to one
hour while troubleshooting. Refer to the sequence of
operations for each mode, to assist in verifying proper
operation. Make the necessary repairs and proceed to

Step 8 and Step 9.

8. If no abnormal operating conditions appear in the test
mode, exit the test mode by turning the power “Off” at
the main power disconnect switch.

9. Refer to the individual component test procedures if
other microelectronic components are suspect.

System Status Checkout
Procedure

“System Status” is checked by using one of the following

two methods:

Method 1

If the Zone Sensor Module (ZSM) is equipped with a
remote panel with LED status indication, you can check the
unit within the space. If the ZSM does not have LED’s, use
Method 2. BAYSENS110*, BAYSENS109*, BAYSENS119*,
BAYSENS023A all have the remote panel indication
feature.The LED descriptions are listed below.

Zone Sensor LED 1 (System)

“On” during normal operation.

“Off” if a system failure occurs or the LED fails.

“Flashing” indicates test mode.

Zone Sensor LED 2 (Heat)

“On” when the heat cycle is operating.

“Off” when the heat cycle terminates or the LED fails.

“Flashing” indicates a heating failure.

60 RT-SVX21P-EN

Troubleshooting

Zone Sensor LED 3 (Cool)

“On” when the cooling cycle is operating.

“Off” when the cooling cycle terminates or the LED fails.

“Flashing” indicates a cooling failure.

Zone Sensor LED 4 (Service)

“On” indicates a clogged filter.

“Off” during normal operation.

“Flashing” indicates an evaporator fan or condensate

overflow switch failure.

Below is the complete listing of failure indication causes.

System failure

Check the voltage between terminals 6 and 9 on J6, it
should read approximately 32 VDC. If no voltage is
present, a system failure has occurred. Refer to Step 4 in
the previous section for the recommended
troubleshooting procedure.

Heating Failure

Verify Heat Failure by Ignition Module (IGN) LED indicator:

OFF: No Power or Failure

ON: Normal

Slow Flash: Normal, Heat Call

Fast Flash: Error Code:

1 Flash: Communication Failure

2 Flashes: System Lockout

3 Flashes: Pressure Switch Fail

4 Flashes: TC01 orTC02 Open

5 Flashes: Flame w/o Gas Valve

6 Flashes: Flame Rollout Open

Cooling Failure

• Cooling and heating set point (slide pot) on the zone
sensor has failed. Refer to the “Zone SensorTest
Procedure” section.

• Zone temperature thermistor ZTEMP on ZTS failed.
Refer to the “Zone SensorTest Procedure” section.

• CC1 or CC2 24 VAC control circuit has opened, check
CC1 & CC2 coils, and any of the controls below that
apply to the unit (HPC1, HPC2).

• LPC1 has opened during the 3 minute minimum “on
time” during 4 consecutive compressor starts, check
LPC1 or LPC2 by testingvoltage between theJ1-1 & J3­2 terminals on the RTRM and ground. If 24 VAC is
present, the LPC’s has not tripped. If no voltage is
present, LPC’s has tripped.

Service Failure

• If the supply fanproving switchhas closed, the unit will
not operate (when connected to RTOM), check the fan
motor, belts, and proving switch.

• Clogged filter switch has closed, check the filters.

• If the condensate overflow switch is closed, the unit
will not operate. Make sure the float switch is not in a
tripped condition, and check for an “open” between
wires connecting to RTOM J6-1, J6-2 (ReliaTel™
controls).

Simultaneous Heat and Cool Failure

• Emergency Stop is activated

Method 2

The second method for determining system status is done

by checking voltage readings at the RTRM (J6).The system
indication descriptions and the approximate voltages are
listed below.

System Failure

• Measure the voltage between terminals J6-9 & J6-6.

• Normal Operation = approximately 32 VDC

• System Failure = less than 1 VDC, approximately 0.75

VDC

• Test Mode = voltage alternates between 32 VDC & 0.75

VDC

Heat Failure

• Measure the voltage between terminals J6-7 & J6-6.

• Heat Operating = approximately 32 VDC

• Heat Off = less than 1 VDC, approximately 0.75 VDC

• Heating Failure = voltage alternates between 32 VDC &

0.75 VDC

Cool Failure

• Measure the voltage between terminals J6-8 & J6-6.

• Cool Operating = approximately 32 VDC

• Cool Off = less than 1 VDC, approximately 0.75 VDC

• Cooling Failure = voltage alternates between 32 VDC &

0.75 VDC

Service Failure

• Measure the voltage between terminals J6-10 & J6-6.

• Clogged Filter = Approximately 32VDC.

• Normal = Less than 1 VDC, approximately 0.75 VDC
Fan Failure =voltage alternates between 32VDC & 0.75

VDC.

To use LED’s for quick status information at the unit,

purchase a BAYSENS110* ZSM and connect wires with
alligator clamps to terminals 6 through10.Connected each

RT-SVX21P-EN 61

Troubleshooting

respective terminal wire (6 through 10) from the Zone
Sensor to the unit J6 terminals 6 through 10.

Note: If the system is equipped with a programmable

zone sensor, BAYSENS119* the LED indicators will
not function while the BAYSENS110* is connected.

Resetting Cooling and Ignition Lockouts

Cooling Failures and Ignition Lockouts are reset in an
identical manner. Method 1 explains resetting the system
from the space; Method 2 explains resetting the system at
the unit.

Note: Before resetting Cooling Failures and Ignition

Lockouts check the Failure Status Diagnostics by
the methods previously explained. Diagnostics will
be lost when the power to the unit is disconnected.

Method 1

To reset the system from the space, turn the “Mode”

selection switch at the zone sensor to the “Off” position.

After approximately 30 seconds, turn the “Mode”

selection switch to the desired mode, i.e. Heat, Cool or

Auto.

Method 2

To reset the system at the unit, cycle the unit power by

turning the disconnect switch “Off” and then “On”.

Lockouts can be cleared through the building
management system. Refer to the building management
system instructions for more information.

Fan Failure Switch

When the “Fan Failure” switch is wired to the RTOM, the

LED will remain flashing the entire time the fan proving
switch is closed, indicating a fan failure,and itwill shut the
unit operations down.

Condensate Overflow Switch

When the “Condensate Overflow Switch” is closed, a

drain pan overflow condition is indicated and it will shut
unit operations down.

Zone Temperature Sensor (ZTS)

Tests

Note: These procedures are not for programmable or

digital models and are conducted with the Zone
Sensor Module electrically removed from the
system.

Test 1 - ZoneTemperatureThermistor

(ZTEMP)

This component is tested by measuring the resistance

between terminals 1 and 2 on the ZoneTemperature
Sensor. Below are some typical indoor temperatures, and
corresponding resistive values.

Test 2 - Cooling Set Point (CSP) and

Heating Set Point (HSP)

Zone Temperature Sensor (ZTS)
Service Indicator

The ZSM SERVICE LED is a generic indicator, that will

signal the closing of a Normally Open switch at any time,
providing the Indoor Motor (IDM) is operating.This
indicator is usually used to indicate a clogged filter, or an
air side fan failure.

The RTRM will ignore the closing of this Normally Open

switch for 2 (±1) minutes.This helps prevent nuisance
SERVICE LED indications.The exception is the LED will
flash 40 seconds after the fan is turned “On” if the Fan
Proving Switch is not made.

Clogged Filter Switch

This LED will remain lit the entire time that the Normally

Open switch is closed.The LED will be turned off
immediately after resetting the switch (to the Normally
Open position), or any time that the IDM is turned “Off”.

If the switch remains closed, and the IDM is turned “On”,
the SERVICE LED will be turned “On” again after the 2 (±1)
minute ignore delay.

This LED being turned “On”, will have no other affect on

unit operation. It is an indicator only.

Table 15. Cooling setpoint and heating setpoint

Zone

Temperature

50 F° 10.0 C° 19.9 K-Ohms
55 F° 12.8 C° 17.47 K-Ohms
60 F° 15.6 C° 15.3 K-Ohms
65 F° 18.3 C° 13.49 K-Ohms
70 F° 21.1 C° 11.9 K-Ohms
75 F° 23.9 C° 10.50 K-Ohms
80 F° 26.7 C° 9.3 K-Ohms
85 F° 29.4 C° 8.25 K-Ohms
90 F° 32.2 C° 7.3 K-Ohms

The resistance of these potentiometers are measured

between the following ZSM terminals. Refer to the chart
above for approximate resistances at the given setpoints.

Cool SP =Terminals 2 and 3

Range = 100 to 900 Ohms approximate

Heat SP =Terminals 2 and 5

Range = 100 to 900 Ohms approximate

Nominal ZTEMP

Resistance

Test3-SystemMode and Fan Selection

The combined resistanceof the Mode selection switch and

the Fan selection switch can be measured between

62 RT-SVX21P-EN

Troubleshooting

terminals 2 and 4 on the Zone Sensor.The possible switch
combinations are listed below with their corresponding
resistance values.

Test 4 - LED IndicatorTest, (SYS ON, HEAT,

COOL & SERVICE)

Method 1

Testing the LED usinga meter with diode test function.Test

both forward and reverse bias. Forward bias should
measure a voltage drop of 1.5 to 2.5 volts, depending on
your meter. Reverse bias will show an Over Load, or open
circuit indication if LED is functional.

Method 2

Testing the LED with an analog Ohmmeter. Connect

Ohmmeter across LED in one direction, then reverse the
leads for the opposite direction.The LED should have at
least 100 times more resistance in reverse direction, as
compared with the forward direction. If high resistance in
both directions, LED is open. If low in both directions, LED
is shorted.

Method 3

To test LED’s with ZSM connected to unit, test voltages at

LED terminals on ZSM. A measurement of 32 VDC, across
an unlit LED, means the LED has failed.

Relative Humidity SensorTest

This component is measured by measuringthe mA output

signal on the Relative Humidity Sensor. Verify accuracy of
the sensor annually. If the output reading is 0 mA, first
verify that power is applied to the sensor. A reading of 4
mA corresponds to 0% RH and20 mA corresponds to 100%
RH.

% RH mA

30 8.8
40 10.4
50 12.0
60 13.6
70 15.2
80 16.8

Note: Measurements should be made from LED common

(ZSM terminal 6 to respective LED terminal).

Programmable & Digital Zone Sensor

Test

Testing serial communication voltage

1. Verify 24VAC is present between terminals J6-14 & J6-

11.

2. Disconnect wires from J6-11 and J6-12. Measure the
voltage between J6-11 and J6-12, should be about 32

VDC.

3. Reconnect wires toterminals J6-11 and J6-12. Measure
voltage again betweenJ6-11 and J6-12, voltage should
flash high and low every 0.5 seconds.The voltage on
the low end will measure about 19VDC, while the
voltage on the high end will measure from
approximately 24 to 38 VDC.

4. Verify all modes of operation, by running the unit
through all of the steps in the “Test Modes” section
discussed in “Unit Start-Up”.

5. After verifying proper unit operation, exit the test
mode.Turn the fan on continuously at the ZSM, by
pressing the button with the fan symbol. If the fan
comes on and runs continuously, the ZSM is good. If
you are not able to turn the fan on, the ZSM is
defective.

ReliaTel™ Refrigeration Module (RTRM)
Default Chart

If the RTCI loses input from the building management
system, the RTRM will control in the default mode after
approximately 15 minutes. If the RTRM loses the Heating
and Cooling setpoint input, the RTRM will control in the
default mode instantaneously.The temperature sensing
thermistor in the Zone Sensor Module is the only
component required for the “Default Mode” to operate.

Unit Operation without a Zone Sensor

This procedure is for temporary operation only.The

economizer and condenser fan cycling functions are
disabled.

WARNING

Hazardous Voltage!

Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized. Failure to disconnect power
before servicing could result in death or serious injury.

1. Open and Lock the unit disconnect switch.

2. Remove the Outside Air Sensor (OAS) from the
condenser section of unit.

3. Use two (2) wire nuts, to individually cap the wires.

4. Locate the RTRM (J6). Connect two (2) wires to
terminals J6-1 and 2.

5. Connect the sensor (OAS) using two wire nuts to the
two (2) field supplied wires that were connected to
terminals 1 and 2 on J6.

RT-SVX21P-EN 63

Troubleshooting

Unit Economizer Control (ECA)

Troubleshooting

ReliaTel™ Control

Verify Economizer Status by Economizer Actuator (ECA)

LED indicator:

• OFF: No power or failure

• ON: Normal, OK to economize

• Slow Flash: Normal, not OK to economize

• Fast Flash - 1/2 second on / 2 seconds off:

• Error Code: Communications failure

• Pulse Flash:2 seconds on / 1/2 second off:

• Error Code:

• 1 Flash: Actuator Fault

• 2 Flashes: CO

• 3 Flashes: RA Humidity Sensor

• 4 Flashes: RA Temp Sensor

• 5 Flashes: OA Quality Sensor

• 6 Flashes: OA Humidity Sensor

• 7 Flashes: OATemp Sensor

• 8 Flashes: MA Temp Sensor

• 9 Flashes: RAM Fault

• 10 Flashes: ROM Fault

• 11 Flashes: EEPROM Fault

Electromechanical Control

The IGN has the ability to provide the service personnel

with some unitdiagnostics and system status information.

Before turning the main power disconnect switch “Off”,
follow the steps below to check the Ignition Module (IGN).

Live Electrical Components!

During installation, testing, servicing and
troubleshooting of this product, it may be necessary to
work with live electrical components. Have a qualified
licensed electrician or other individual who has been
properly trained in handling live electrical components
perform these tasks. Failure to follow all electrical
safety precautions when exposed to live electrical
components could result in death or serious injury.

To prevent injury or death from electrocution, it is the

responsibility of the technician to recognize this hazard
and use extreme care when performing service
procedures with the electrical power energized.

1. Verify LED onface ofthe phase monitor is green.If LED
is red, correct supply power fault.

Sensor

2

WARNING

2. Verify that the LED on the IGN is burning continuously.
If the LED is lit, go to Step 4.

3. If the LED is not lit, verify that 24 VAC is present
between R and B. If the LED is not lit and 24 VAC is
present replace the IGN. If 24VAC is not present, check
transformer (TNS1). Proceed to Step 4 if necessary.

4. If no failures are indicated, use the TEST mode
procedures described in the “Unit Start-Up” section or
thermostat to start the unit.This procedure will allow
you to check all of the external controls (relays,
contactors, etc) and the IGN.

5. Test thesystem through all of the availablemodes, and
verify operation of all outputs, controls, and modes.
Refer to the sequence of operations for each mode, to
assist in verifying proper operation. Make the
necessary repairs and proceed to Step 6 and Step 7.

6. If no abnormal operating conditions appear in the test
mode, exit the test mode by turning the power “Off” at
the main power disconnect switch and removing the
test mode connections.

7. Refer to the individual component test procedures if
other components are suspect.

Heating Failure

Verify Heat Failure by Ignition Module (IGN) LED indicator:

• OFF: No Power or Failure

• ON: Normal

• Slow Flash: Normal, Heat Call

• Fast Flash: Error Code:

1 Flash: No Communication

2 Flashes: System Lockout

3 Flashes: Pressure Switch Fail

4 Flashes:TC01 orTC02 Open

5 Flashes: Flame w/o Gas Valve

6 Flashes: Flame Rollout Open

Cooling Failure

• Cooling and heating set point (slide pot) on the
thermostat has failed.

• CC1 or CC2 24 VAC control circuit has opened, check
CC1 & CC2 coils, and any of the controls below that
apply to the unit (HPC1, HPC2, LPC1, LPC2, Frostat™).

Resetting Cooling and Ignition Lockouts

Cooling Failures and Ignition Lockouts are reset in an
identical manner. Method 1 explains resetting the system
from the space; Method 2 explains resetting the system at
the unit.

Method 1

To reset the system from the space, turn the “Mode”

selection switch at the thermostat to the “Off” position.

64 RT-SVX21P-EN

Troubleshooting

After approximately 30 seconds, turn the “Mode”

selection switch to the desired mode, i.e. Heat, Cool or

Auto.

Table 16. Fault detection and diagnostic codes

Primary Fault Codes Information Code

Mixed Air

Failures

Damper stuck
at Minimum

Damper Stuck
Open

Mixed Sensor
Failure

Supply Air
Sensor Failure

Outdoor Air
Temperature
Fail

Power loss to
RTEM

Failed or Power
Loss to
Actuator

Mechanical
Failure of
Actuator

(a)If goes out of range.

Sensor

Temp

Fail

Outdoor

Temp

Sensor

Fail

Economizer

Actuator

Fault

Comm

RTEM

Fail

Pressure

Dead band

Fail

(If Used)

XX

XX

X X

X X

X

X X

(a)

(a)

Method 2

To reset the system at the unit, cycle the unit power by

turning the disconnect switch “Off” and then “On”.

Temp

Sensor

Fail

(If Used)

Airflow

Sensor Fail

(If Used)

(a)

X

(a)

X

XX

X

Space

Press Dead

band Fail
(If Used)

*X

X

(a)

(a)

Unit Fails

to

Economize

XX

Unit

Economizing

When It

Should Not

Damper

Position %

Indicated

XX

Table 17. Low leak economizer sensor values

Temp °F

40 26.097 54 17.847 68 12.435
41 25.383 55 17.382 69 12.126
42 24.690 56 16.930 70 11.827
43 24.018 57 16.491 71 11.535
44 23.367 58 16.066 72 11.252
45 22.736 59 15.654 73 10.977
46 22.132 60 15.253 74 10.709
47 21.530 61 14.864 75 10.448
48 20.953 62 14.486 76 10.194
49 20.396 63 14.119 77 9.949
50 19.854 64 13.762 78 9.710
51 19.330 65 13.416 79 9.477
52 18.821 66 13.078 80 9.250
53 18.327 67 12.752 81 9.030

Resistance

(K ohms) Temp °F

Sensor Values Data

Resistance

(K ohms) Temp °F

Resistance

(K ohms)

RT-SVX21P-EN 65

Troubleshooting

Unit Economizer Control (ECA)

Test Procedures

Electromechanical Control

This series of tests will allow you to diagnose, and

determine where, and if a problem exists in the system
economizer operation.Test 1 determines if the problem is
in the Unit, or if it is in the ECA.Test 2 tests sensor inputs.

Test 3 tests the resistors and sensors. Conduct the tests in

numerical order until problem is found.

Test 1

Verifying that the economizer actuator (ECA) is functional:

1. Using the “Test Mode” described in the “System Start­Up” section, put the unit into the economizer mode
and verify that the economizer actuator (ECA) drives
fully open (approximately 90 seconds).

2. If the ECA is not driving the dampers, verify that 24VAC
is between the ECA terminalsTR andTR1 is present. If
24 volts is not present, a wiring or terminal problem
exists from the control transformer. Make any
necessary repairs, see wiring diagrams to
troubleshoot.

3. If 24 VAC is present, adjust the minimum position
potentiometer fully clockwise. If the actuator does not
drive, the economizer actuator is bad. Replace the ECA.

The resistance should be approximately 130 Ohms.

Replace the ECA if it is out of range.

Troubleshooting procedures for

Direct Drive Plenum Fan

Prior to troubleshooting, verify all wiring and wiring
connections.The motor has internal protections that will
shut down the motor before damage occurs. A power
cycle is required to reset some of the internal protections.
Before proceeding, powerdown unit for 1minute and then
power on.

Please follow steps sequentially unlessdirected differently
in solution.

Refer to RT-SVB90*-EN for a Comprehensive

Troubleshooting Guide.

Test 2

Testing the ECA resistors and sensors

1. Testing the Mixed Air Sensor (MAS). Disconnect the
wires connected toT andT1 on the ECA, and;

a. Measure the resistance of the sensor between the

wires 180B and 181B.

b. Measure the temperature at the MAS location.

Using theTemperature versus Resistance chart,
verify the accuracy of the MAS.

Replace the sensor if it is out of range.

2. Testing the Outdoor Air Switch. If the temperature is
above 60 degrees, it will need to be chilled. Measure
the resistance of the sensor on the ECA SO and +.

The resistance should be approximately 390 Ohms.

Replace the Switch if it is open.

Replace the ECA if it is out of range.

3. Testing the R1 Resistance.

Measure the resistance of the sensor on the ECA SR
and +.

The resistance should be approximately 420 Ohms.

Replace the ECA if it is out of range.

4. Testing the R2 Resistance.

Measure the resistance of the sensor on the ECA P and
P1.

66 RT-SVX21P-EN

Unit Wiring Diagrams Numbers

Note: Wiring diagrams can be accessed using e-Library

by entering the diagram number in the literature
order number search field or by contacting
technical support.

Table 18. Unit wiring diagram numbers

Schematic Type Drawing Number Description

4366-7217 YHC(037-067)
4366-4571 Y(S,H)C(036,048)E/F, ReliaTel Controls, X13 IDM
4366-1015 Y(S,H)C(036-090)E/F, ReliaTel Controls, Belt-Drive IDM

ReliaTel™

Control

230,460,575V

Electromechanical

Schematic Type Drawing Number Description

230V

ReliaTel™

Power

460V and/or 575V

230V

Electromechanical

460V and/or 575V

Schematic Type Drawing Number Description

Connection ReliaTel™ 230V

4366-4703 Y(S,H)C060E/F, ReliaTel Controls, X13 IDM
4366-1042 YSC(092,102)F, ReliaTel Controls
4366-7436 (YHC092-102,YSC120)F, ReliaTel Controls
4366-7430 YHC120E, ReliaTel Controls

4366-8386

4366-8383
4366-8387 Y(S,H)C060E/F, Electromechanical Controls, X13 IDM

4366-8385 Y(S,H)C(072,090)F, Electromechanical Controls
4366-8384 YSC(092,102)F, Electromechanical Controls
4366-8388 (YHC092-102,YSC120)F, Electromechanical Controls
4366-8395 YHC120E, Electromechanical Controls

4366-7179 YHC(037-067) (230V)
4366-4576 Y(S,H)C(036-060)E/F (1-Phase)
4366-5163 YHC(036-060)E/F (230V 3-Phase), X13 IDM
4366-1016 Y(S,H)C(036-090)E/F (230V 3-Phase), Belt-Drive IDM
4366-1033 YSC(092,102)F (230V)
4366-7437 (YHC092-102, YSC120)F (230V), ReliaTel Controls
4366-7430 YHC120E, ReliaTel Controls
4366-7180 YHC(037-067) (460V)
4366-5164 YHC(036-060)E/F (460V), X13 IDM
4366-1005 Y(S,H)C(036-090)E/F (460V,575V), Belt-Drive IDM
4366-1034 YSC(092,102)F (460V,575V)
4366-7438 (YHC092-102, YSC120)F (460V), ReliaTel Controls
4366-7439 YSC120F (575V), ReliaTel Controls
4366-7430 YHC120E, ReliaTel Controls
4366-6406 YHC(092-120)E, Electromechanical Controls
4366-6449 YHC(092-102)F, YSC120F, Electromechanical Controls
4366-6406 YHC120E, Electromechanical Controls
4366-6436 YHC(092-102)F4, Electromechanical Controls
4366-6782 YSC(120)FW, Electromechanical Controls

4366-7340 YHC(037) (230V)
4366-8247 YHC037E (230V), 17 Plus with Multi-Zone VAV
4366-7342 YHC(047-067) (230V)
4366-8249 YHC(047, 067)E (230V), 17 Plus with Multi-Zone VAV
4366-4564 Y(S,H)C(036,048)E/F (1-Phase), ReliaTel Controls

4366-5185

4366-1522
4366-4705 Y(S,H)C060E/F (1-Phase), ReliaTel Controls

4366-5186 YHC060E/F (230V 3-Phase), R eliaT el Controls, X13 IDM
4366-1539 Y(S,H)C(072,090)F (230V), ReliaTel Controls
4366-7449 YHC120E (3-Phase), ReliaTel Controls

Y(S,H)C(036,048)E/F , Electromechanical Controls, X13

IDM

Y(S,H)C(036-060)E/F, Electromechanical Controls,

Belt-Drive IDM

YHC(036,048)E/F (230V 3-Phase), ReliaTel Controls,

X13 IDM

Y(S,H)C(036-060)E/F (230V 3-Phase), ReliaTel

Controls, Belt-Drive IDM

RT-SVX21P-EN 67

Unit Wiring Diagrams Numbers

Table 18. Unit wiring diagram numbers (continued)

230V

ReliaTel™

460V and/or 575V

Connection

230V

Electromechanical

460V and/or 575V

4366-8254 YHC(092-120)E ReliaTel Controls, with Multi-Zone VAV
4366-1530 YSC(092,102)F (230V), ReliaTel Controls
4366-7451 (YSC120,YHC092-102)F (230V), ReliaTel Controls

4366-8255
4366-8254 YHC(092-120)E ReliaTel Controls, with Multi-Zone VAV

4366-7341 YHC(037) (460V)
4366-8248 YHC037E (460V), 17 Plus with Multi-Zone VAV
4366-7343 YHC(047-067) (460V)
4366-8250 YHC(047,067)E (460V), 17 Plus with Multi-Zone VAV
4366-5202 YHC(036,048)E/F (460V), ReliaTel Controls, X13 IDM

4366-1516
4366-5203 YHC060E/F (460V), ReliaTel Controls, X13 IDM

4366-1540 Y(S,H)C(072,090)F (460V,575V), ReliaTel Controls
4366-1532 YSC(092,102)F (460V,575V), ReliaTel Controls
4366-7454 (YSC120,YHC092-102)F (460V), ReliaTel Controls

4366-8256
4366-7456 YSC120F (575V), ReliaTel Controls

4366-8257 YSC120F (575V), ReliaTel Controls with Multi-Z one V AV
4366-8390

4366-8392

4366-8404
4366-8391 Y(S,H)C060E/F (1-Phase), Electromechanical Controls
4366-8393
4366-8408 Y(S,H)C(072,090)F (230V), Electromechanical Controls

4366-8403 YHC120E (3-Phase), Electromechanical Controls
4366-8406 YSC(092,102)F (230V), Electromechanical Controls

4366-8400

4366-8394

4366-8405

4366-8399

4366-8389

4366-8407

4366-8401
4366-8402 YSC120F (575V), Electromechanical Controls

YHC(092-102)F , YSC120F (230V), ReliaT el Controls with

Multi-Zone VAV

Y(S,H)C(036-060)F (460V,575V), ReliaTel Controls,

Belt-Drive IDM

YHC(092-102)F , YSC120F (460V), ReliaT el Controls with

Multi-Zone VAV

Y(S,H)C(036,048)E (1-Phase), Electromechanical

Controls

YHC(036,048)E/F (230V 3-Phase), Electromechanical

Controls, X13 IDM

Y(S,H)C(036-060)E/F (230V 3-Phase),

Electromechanical Controls, Belt-Drive IDM

YHC060E/F (230V 3-Phase), Electromechanical

Controls, X13 IDM

(YSC120,YHC092-102)F (230V), Electromechanical

Controls

YHC(036,048)E/F (460V), Electromechanical Controls,

X13 IDM

Y(S,H)C(036-060)E/F (460V ,575V), Electromechanical

Controls, Belt-Drive IDM

YHC060E/F (460V), Electromechanical Controls, X13

IDM

Y(S,H)C(072,090)F (460V,575V), Electromechanical

Controls

YSC(092,102)F (460V,575V), Electromechanical

Controls

(YSC120,YHC092-102)F (460V), Electromechanical

Controls

68 RT-SVX21P-EN

Limited Warranty

Combination Gas Electric Air
Conditioner

YCC, YCD,YCH,YCP, YSC and YHC (Parts

Only)

Models Less Than 20 Tons for Residential
Use*

This limited warranty is extended byTrane to the original

purchaser and to any succeeding owner of the real
property to which the Combination Gas Electric Air
Conditioner is originally affixed, and applies to products
purchased and retained for use within the U.S.A. and
Canada.

If any part of your Combination Gas Electric Air
Conditioner fails becauseof a manufacturingdefect within
five years from the date of the original purchase,

Warrantor will furnish without charge the required

replacement part.Any local transportation, related service
labor, diagnosis calls, air filters, refrigerant and related
items are not included.

If the sealed motor-compressor fails because of a
manufacturing defect within five years from the date of
original purchase, Warrantor will furnish without charge
the required replacement compressor. Any local
transportation, related service labor, diagnosis calls,
refrigerant and related items are not included.

In addition, if theoptional, factory installed, stainless steel
heat exchanger fails because of a manufacturing defect
within ten years from the date of start-up, Warrantor will
furnish without charge a replacement heat exchanger. Any
local transportation, related service labor and diagnosis
calls are not included.

This limited warranty does not cover failure of your

combination gas electric air conditioner if it is damaged
while in your possession, failure attributable or caused by
unreasonable use of the combination gas electric air
conditioner and/or failure to properly maintain the
combination gas electric air conditioner as set forth in the
Use and Care manual.

This limited warranty applies to product installed on or

after 10/1/2001 where product is manufactured after 1/1/

2000.This limited warranty is not retroactive to any

installations prior to 10/1/2001 or on product produced
prior to 2000.

THE LIMITED WARRANTY AND LIABILITY SET FORTH

HEREIN ARE IN LIEU OF ALL OTHER WARRANTIES AND
LIABILITIES, WHETHER IN CONTRACT OR IN
NEGLIGENCE, EXPRESS ORIMPLIED, IN LAW OR INFACT,
INCLUDING IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR PARTICULAR
USE, AND IN NO EVENT SHALL WARRANTOR BE LIABLE
FOR ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES.

Some states do not allow limitations on how long an
implied limited warranty lasts or do not allow the
exclusion or limitation of incidental or consequential
damages, so the above limitation or exclusion may not
apply to you.This limited warranty gives you specific legal
rights, and youmay also have otherrights whichvary from
state to state.

Parts will be provided by our factory organization through
an authorized service organizationin your area listedin the
yellow pages. If you wish further help or information
concerning this limited warranty, contact:

Trane

2701 Wilma Rudolph Blvd.

Clarksville,TN 37040-1008

Attention: Manager, Product Service

GW-618-4001

*This limited warranty is for residential usage of this
equipment and not applicable when this equipment is
used for a commercial application. A commercial use is
any application where the end purchaser uses the product
for other than personal, family or household purposes.

Combination Gas Electric Air
Conditioner

YCZ, YCY, YCX,YCC, YCD,YCH,YCP, YHC

and YSC (Parts Only)

Models Less Than 20 Tons for Commercial
Use*

This warranty is extended byTrane to the original

purchaser and to any succeeding owner of the real
property to which the Combination Gas Electric Air
Conditioner is originally affixed, and applies to products
purchased and retained for use within the U.S.A. and
Canada.There is no warranty against corrosion, erosion or
deterioration.

If any part of your Combination Gas Electric Air
Conditioner fails becauseof a manufacturingdefect within
one year from the date of the original purchase, Warrantor
will furnish without charge the required replacement part.

In addition, if the sealed motor-compressor fails because
of a manufacturing defect within the second through fifth
year from the date of original purchase, Warrantor will
furnish without charge the required replacement
compressor.

In addition, if theoptional, factory installed, stainless steel
heat exchanger fails because of a manufacturing defect
within ten years from the date of start-up, Warrantor will
furnish without charge a replacement heat exchanger. Any
local transportation, related service labor and diagnosis
calls are not included.

RT-SVX21P-EN 69

Limited Warranty

Warrantor’s obligations and liabilities under this warranty

are limited to furnishing F.O.B. Warrantor factory or
warehouse at Warrantor designated shipping point,

freight allowed to Buyer’s city, replacement parts for
Warrantor’s products covered under this warranty.
Warrantor shall not be obligated to pay for the cost of lost

refrigerant. No liability shall attach to Warrantor until

products have been paid for and then liability shall be

limited solely to the purchase price of the equipment

under warranty shown to be defective.

THEWARRANTYAND LIABILITY SET FORTH HEREINARE

IN LIEU OF ALL OTHER WARRANTIES AND LIABILITIES,
WHETHER IN CONTRACT OR IN NEGLIGENCE, EXPRESS

OR IMPLIED, IN LAW OR IN FACT, INCLUDING IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

PARTICULAR USE, AND IN NO EVENT SHALL
WARRANTOR BE LIABLE FOR ANY INCIDENTAL OR

CONSEQUENTIAL DAMAGES.

Some states do not allow limitations on how long an

implied warranty lasts or do not allow the exclusion or

limitation of incidental or consequential damages, so the

above limitation or exclusion may not apply to you.This

warranty gives you specific legal rights, and you may also

have other rights which vary from state to state.

Trane

2701 Wilma Rudolph Blvd.

Clarksville,TN 37040-1008

Attention: Manager, Product Service

GW-606-4800

*This warranty is for commercial usage of said equipment

and not applicable when the equipment is used for a

residential application. Commercial use is any application

where the end purchaser uses the product for other than

personal, family or household purposes.

**A 5 year limited warranty is provided for the optional

"Low Leak" economizer when combined with the

additional FDD (Fault Detection & Diagnostics) option.

70 RT-SVX21P-EN

The manufacturer optimizes the performance of homes and buildings around the world. A business of Ingersoll Rand,
the leader in creating and sustaining safe, comfortable and energy efficient environments,the manufacturer offers a
broad portfolio of advanced controls and HVAC systems, comprehensive building services, and parts. For more
information, visit www.IRCO.com.

The manufacturer has a policy of continuous product and product data improvement and reserves the right to change design and specifications without notice.

© 2014Trane All rights reserved

RT-SVX21P-EN 11 July 2014

Supersedes RT-SVX21N-EN (04 Sep 2013)

We are committed to using environmentally

conscious print practices that reduce waste.