Ingersol Rand TSC072F Series Service manual

SAFETY WARNING
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.
Packaged Rooftop Air Conditioners
Precedent™ – Cooling, Gas/Electric
6Ton Standard Efficiency Rooftop Units
Service Facts
Model Numbers TSC072F* YSC072F*
RT-SVF25C-EN
July 2014

© 2014Trane All rights reserved RT-SVF25C-EN
Introduction
Read this manual 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.
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.
The three types of advisories are defined as follows:
WARNING Indicates a potentially hazardous
situation which, if not avoided, could
result in death or serious injury.
CAUTIONsIndicates a potentially hazardous
situation which, if not avoided, could
result in minor or moderate injury. It
could also be used to alert against
unsafe practices.
NOTICE Indicates a situation that could result in
equipment or property-damage only
accidents.
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
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.

Introduction
RT-SVF25C-EN 3
Copyright
This document and the information in it are the property of
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-SVF25C-EN (11 July 2014)
• Added Low Leak Economizer Factory and Field
Installed Option

4 RT-SVF25C-EN
Table of Contents
Introduction ............................. 2
Warnings, Cautions, and Notices ........ 2
Important Environmental Concerns ..... 2
Important Responsible Refrigerant Practices
2
Copyright ............................. 3
General Data ............................ 5
Evaporator Fan Performance ............. 6
Performance Data ...................... 12
Electrical Data .......................... 13
Sequence of Operation .................. 15
ReliaTel Controls ..................... 15
ReliaTel Control Cooling without an Econo-
mizer ............................. 15
Three-Stages of Cooling ............. 15
ReliaTel Control Evaporator Fan Operation
(for Gas Units) ..................... 15
ReliaTel Control Evaporator Fan Operation
(for Cooling Only Units) .............. 16
Low Ambient Operation .............. 16
ReliaTel Control Dehumidification ..... 16
Dehumidification Coil Purge Cycle ..... 16
ReliaTel Control Cooling with
an Economizer ..................... 17
Economizer Set-Up .................. 17
ReliaTel Control Heating Operation (for Cool-
ing Only Units) ..................... 17
ReliaTel Control Heating Operation (for Gas
Units) ............................. 17
Ignition Module .................... 17
Drain Pan Condensate Overflow Switch (Op-
tional) ............................ 18
Electromechanical Controls ............ 18
Electromechanical Control Cooling without
an Economizer ..................... 18
Electromechanical Control Evaporator Fan
Operation (for Gas Units) ............. 18
Electromechanical Evaporator Fan Operation
(for Cooling Only Units) .............. 19
Economizer Set-Up .................. 19
Electromechanical Control Cooling with an
Economizer ........................ 19
Electromechanical Control Heating Operation
(for Cooling Only Units) ...............19
Electromechanical Control Heating Operation
(for Gas Units) ......................19
Ignition Module Low, Medium and
High Heat ..........................19
Drain Pan Condensate Overflow Switch (Op-
tional) .............................20
Pressure Curve ..........................21
To Check Operating Pressures .........21
Subcooling Charging Chart ...............22
Refrigerant Circuit .......................23

RT-SVF25C-EN 5
General Data
Table 1. General data-6tons- standard efficiency
6 Tons
T/YSC072F3,4,W
Cooling Performance(a)
Gross Cooling Capacity
EER(b)
Nominal cfm/ARI Rated cfm
ARI Net Cooling Capacity
IEER(c)
System Power (kW)
75,000
11.2
2,400/2,100
71,000
13.0
6.36
Compressor
Number/Type 1/Scroll
Sound
Outdoor Sound Rating (dB)(d) 89
Outdoor Coil - Type Microchannel
Configuration
MC Thickness (in.)
Face Area (sq. ft.)
Rows/FPI
Full Face
0.71
16.91
1/23
Indoor Coil - Type Lanced
Configuration
Tube Size (in.)
Face Area (sq. ft.)
Rows/FPI
Refrigerant Control
Drain Connection Number/Size (in.)
Full Face
0.3125
9.89
3/16
Thermal Expansion Valve
1¾ NPT
Outdoor Fan - Type Propeller
Number Used/Diameter (in.)
Drive Type/No. Speeds
cfm
Motor hp
Motor rpm
1/26
Direct/1
6,037
0.7
1,100
Indoor Fan - Type FC Centrifugal
Number Used/Diameter (in.)/Width
(in.)
Drive Type/No. Speeds/rpm
Motor hp (Standard/Oversized)
Motor Frame Size (Standard/
Oversized)
1/12x12
Belt/Variable/1,750
1.0/2.0
56/56
Filters(e)
Type Furnished
Number Size Recommended Throwaway (4) 16x25x2
Refrigerant Charge (f)
Pounds of R-410A 5.5
Heating Performance(g)
(Gas/Electric Only)
Heating Input
Low Heat Input (Btu)
Mid Heat Input (Btu)
High Heat Input (Btu)
80,000
120,000
150,000/105,000
Heating Output
Low Heat Input (Btu)
Mid Heat Input (Btu)
High Heat Input (Btu)
64,000
96,000
120,000/84,000
AFUE%(h)
Low Heat Input (Btu)
Mid Heat Input (Btu)
High Heat Input (Btu)
80
80
80
Steady State Efficiency%
Low Heat Input (Btu)
Mid Heat Input (Btu)
High Heat Input (Btu)
80
80
80
No. Burners
Low Heat Input (Btu)
Mid Heat Input (Btu)
High Heat Input (Btu)
2
3
3
No. Stages
Low Heat Input (Btu)
Mid Heat Input (Btu)
High Heat Input (Btu)
1
1
2
Gas Supply Line Pressure
Natural (minimum/maximum)
LP (minimum/maximum) 4.5/14.0 11.0/14.0
Gas Connection Pipe Size (in)
Low Heat
Mid Heat
High Heat
1/2
1/2
3/4
(a)Cooling performance is rated at 95°F ambient, 80°F entering dry bulb,
67°F entering wet bulb. Gross capacity does not include the effect of
fan motor heat. ARI capacity is net and includes the effect of fan motor
heat. Units are suitable for operation to ±20% of nominal cfm. Units
are certified in accordance with the Unitary Air-Conditioner Equipment
certification program, which is based on ARI Standard 340/360.
(b)EER is rated at ARI conditions and in accordance with DOE test proce-
dures.
(c) Integrated Efficiency Ratio (IEER) is rated in accordance with ARI Stan-
dard 340/360. The IEER rating requires that the unit efficiency be de-
termined at 100%, 75%, 50% and 25% load (net capacity) at the
specified in ARI Standard.
(d)Outdoor Sound Rating shown is tested in accordance with ARI Standard
270. For additional information refer to Table 11, p. 12.
(e) Optional 2” MERV 8 and MERV 13 filters also available.
(f) Refrigerant charge is an approximate value. For a more precise value,
see unit nameplate and service instructions.
(g)Heatingperformance limitsettingsandratingdatawereestablishedand
approved under laboratory test conditions using American National
Standards Institute standards. Ratings shown are for elevations up to
2000 feet. For elevations above 2000 feet, ratings should be reduced
at the rate of 4% for each 1000 feet above sea level. Applicable to Gas/
Electric units only.
(h)AFUE is rated in accordance with DOE test procedures.
Table 1. General data-6tons- standard efficiency
6 Tons
T/YSC072F3,4,W

6 RT-SVF25C-EN
Evaporator Fan Performance
Table 2. Belt drive evaporator fan performance-6tonsstandard efficiency - TSC072F3,4,W downflow airflow
External Static Pressure (Inches of Water)
0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
1-hp Standard Motor & Field Supplied Low Static Drive(a) 1-hp Standard Motor & Drive
1920 — — — — 588 0.35 643 0.43 693 0.50 738 0.57 782 0.65 823 0.73 862 0.81 900 0.89
2160 — — 564 0.37 618 0.44 672 0.52 721 0.60 765 0.68 806 0.76 847 0.85 885 0.93 922 1.02
2400 — — 602 0.47 652 0.54 701 0.63 750 0.72 794 0.81 834 0.90 873 0.98 909 1.08 945 1.17
2640 589 0.50 642 0.59 690 0.67 734 0.76 779 0.85 822 0.95 864 1.05 901 1.15 936 1.24 971 1.34
2880 634 0.63 682 0.74 728 0.82 770 0.91 810 1.01 851 1.11 892 1.22 930 1.33 965 1.44 999 1.54
Continued
External Static Pressure (Inches of Water)
1.10 1.20 1.30 1.40 1.50 1.60 1.70 1.80 1.90 2.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
1-hp Standard Motor & Drive 1-hp Standard Motor & High Static Drive Kit (or 2-hp Oversized Motor & Drive)
1920 937 0.98 971 1.06 1004 1.14 1037 1.22 1068 1.30 1097 1.38 1127 1.47 1154 1.55 1182 1.64 1210 1.74
2160 957 1.12 991 1.21 1024 1.30 1057 1.40 1087 1.49 1117 1.58 1146 1.67 1174 1.76 1201 1.85 1227 1.95
2400 980 1.27 1013 1.37 1046 1.47 1076 1.57 1106 1.68 1137 1.78 1166 1.89 1194 1.99 1220 2.08 1248 2.19
2640 1004 1.44(b) 1036 1.55 1067 1.65 1098 1.77 1129 1.88 1158 1.99 1185 2.10 1214 2.22 — — — —
2880 1030 1.64 1061 1.75 1092 1.86 1123 1.98 1151 2.09 1181 2.22 — — — — — — — —
2-hp Oversized Motor & Drive
Notes:
1. For Standard Evaporator Fan Speed (rpm), reference Table 8, p. 12.
2. Data includes pressure drop due to standard filters and wet coils. No accessories or options are included in pressure drop data.
3. Refer to Table 12, p. 12 to determine additional static pressure drop due to other options/accessories.
4. 1-hp Fan Motor Heat (MBh) = 2.829 x Fan bhp + 0.4024. 2-hp Fan Motor Heat (MBh) = 3.000 x Fan bhp + 0.5000.
5. Factory supplied motors, in commercial equipment, are definite purpose motors, specifically designed and tested to operate reliably and continuously
at all cataloged conditions. Using the full horse power range of our fan motors as shown in our tabular data will not result in nuisance tripping or
premature motor failure. Our product's warranty will not be affected.
(a)Field Supplied Fan Sheave AK84 and Belt AX36 required.
(b)1-hp Standard Motor & High Static Drive Kit (or 2-hp Oversized Motor & Drive)

Evaporator Fan Performance
RT-SVF25C-EN 7
Table 3. Belt drive evaporator fan performance-6tonsstandard efficiency - TSC072F3,4,W horizontal airflow
External Static Pressure (Inches of Water)
0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
1-hp Standard Motor & Field Supplied Low Static Drive(a) 1-hp Standard Motor & Drive
1920 — — 580 0.33 641 0.41 692 0.47 738 0.54 783 0.63 827 0.71 870 0.79 912 0.88 951 0.96
2160 578 0.37 623 0.43 679 0.51 731 0.59 775 0.67 817 0.74 857 0.83 896 0.93 935 1.02 974 1.12
2400 633 0.49 673 0.56 718 0.63 769 0.72 814 0.82 855 0.90 893 0.98 929 1.08 965 1.18 999 1.29
2640 688 0.64 725 0.71 762 0.79 808 0.87 853 0.98 894 1.09 931 1.17 966 1.26 1000 1.36 1032 1.47(b)
2880 743 0.81 778 0.90 811 0.98 848 1.06 891 1.16 932 1.28 970 1.40 1004 1.49 1037 1.59 1068 1.69
1-hp Standard Motor & High Static Drive Kit (or 2-hp Oversized Motor)
Continued
External Static Pressure (Inches of Water)
1.10 1.20 1.30 1.40 1.50 1.60 1.70 1.80 1.90 2.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
1-hp Standard Motor & Drive 1-hp Standard Motor & High Static Drive Kit (or 2-hp Oversized Motor & Drive)
1920 990 1.05 1026 1.14 1062 1.24 1096 1.33 1130 1.43 1160 1.52 1190 1.61 1218 1.71 1247 1.80 1273 1.90
2160 1010 1.21 1047 1.31 1082 1.40 1116 1.50 1150 1.61 1182 1.71 1211 1.81 1242 1.92 1271 2.03 1298 2.14
2400 1035 1.39 1070 1.50 1104 1.60 1137 1.70 1168 1.81 1201 1.92 1232 2.03 1261 2.14 1291 2.26 — —
2640 1065 1.59 1097 1.71 1129 1.82 1161 1.93 1192 2.05 1223 2.16 1252 2.27 — — — — — —
2880 1099 1.80 1130 1.93 1159 2.05 1188 2.18 1217 2.30 — — — — — — — — — —
2-hp Oversized Motor & Drive 2-hp Oversized Motor & Field Supplied Drive(c)
Notes:
1. For Standard Evaporator Fan Speed (rpm), reference Table 8, p. 12.
2. Data includes pressure drop due to standard filters and wet coils. No accessories or options are included in pressure drop data.
3. Refer to Table 12, p. 12 to determine additional static pressure drop due to other options accessories.
4. 1-hp Fan Motor Heat (MBh) = 2.829 x Fan bhp + .4024. 2-hp Fan Motor Heat (MBh) = 3.000 x Fan bhp + .5000.
5. Factory supplied motors, in commercial equipment, are definite purpose motors, specifically designed and tested to operate reliably and continuously
at all cataloged conditions. Using the full horsepower range of our fan motors as shown in our tabular data will not result in nuisance tripping or
premature motor failure. Our product's warranty will not be affected.
(a)Field Supplied Fan Sheave AK84 and Belt AX36 required.
(b)2-hp Oversized Motor & Field Supplied Drive
(c) Field Supplied Fan Sheave AK56 and Belt AX30.

Evaporator Fan Performance
8 RT-SVF25C-EN
Table 4. Belt drive evaporator fan performance-6tonsstandard efficiency with gas heat -YSC072F3,4,W*L,M low &
medium heat downflow airflow
External Static Pressure (Inches of Water)
0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
1-hp Standard Motor & Field Supplied Low Static Drive(a) 1-hp Standard Motor & Drive
1920 — — — — 597 0.37 652 0.44 700 0.51 745 0.58 788 0.66 829 0.74 869 0.82 906 0.91
2160 — — 575 0.38 629 0.46 683 0.54 730 0.62 774 0.70 815 0.78 854 0.86 893 0.95 929 1.04
2400 561 0.41 615 0.49 664 0.57 714 0.65 762 0.74 805 0.83 844 0.92 882 1.01 918 1.10 954 1.20
2640 606 0.53 657 0.62 703 0.70 747 0.79 792 0.88 835 0.98 875 1.08 912 1.18 947 1.27 980 1.37
2880 651 0.67 699 0.77 743 0.85 785 0.94 825 1.05 867 1.15 906 1.26 943 1.37 978 1.47 1010 1.58
2-hp Oversized Motor & Drive
Continued
External Static Pressure (Inches of Water)
1.10 1.20 1.30 1.40 1.50 1.60 1.70 1.80 1.90 2.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
1-hp Standard Motor & Drive 1-hp Standard Motor & High Static Drive Kit (or 2-hp Oversized Motor & Drive)
1920 941 0.99 977 1.07 1009 1.15 1041 1.23 1073 1.32 1103 1.40 1132 1.49 1159 1.57 1187 1.66 1213 1.75
2160 964 1.13 997 1.23 1031 1.32 1061 1.41 1093 1.50 1123 1.60 1151 1.69 1179 1.78 1207 1.87 1234 1.97
2400 988 1.29 1020 1.39 1054 1.50 1085 1.60 1114 1.70 1143 1.80 1171 1.90 1200 2.01 1227 2.11 1254 2.21
2640 1014 1.47(b) 1046 1.58 1077 1.69 1107 1.80 1138 1.91 1166 2.02 1193 2.13 1222 2.25 — — — —
2880 1042 1.68 1073 1.79 1103 1.90 1132 2.02 1162 2.14 1190 2.26 — — — — — — — —
2-hp Oversized Motor & Drive
Notes:
1. For Standard Evaporator Fan Speed (rpm), reference Table 8, p. 12.
2. Data includes pressure drop due to standard filters and wet coils. No accessories or options are included in pressure drop data.
3. Refer to Table 12, p. 12 to determine additional static pressure drop due to other options/accessories.
4. 1-hp Fan Motor Heat (MBh) = 2.829 x Fan bhp + .4024. 2-hp Fan Motor Heat (MBh) = 3.000 x Fan bhp + .5000
5. Factory supplied motors, in commercial equipment, are definite purpose motors, specifically designed and tested to operate reliably and continuously
at all cataloged conditions. Using the full horsepower range of our fan motors as shown in our tabular data will not result in nuisance tripping or
premature motor failure. Our product's warranty will not be affected.
(a)Field Supplied Fan Sheave AK84 and Belt AX36 required.
(b)1-hp Standard Motor & High Static Drive Kit (or 2-hp Oversized Motor & Drive)

Evaporator Fan Performance
RT-SVF25C-EN 9
Table 5. Belt drive evaporator fan performance-6tonsstandard efficiency with gas heat -YSC072F3,4,W*L,M low &
medium heat horizontal airflow
External Static Pressure (Inches of Water)
0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
1-hp Standard Motor & Field Supplied Low Static Drive(a) 1-hp Standard Motor & Drive
1920 — — 591 0.34 649 0.42 699 0.48 745 0.56 789 0.64 834 0.72 877 0.81 918 0.89 957 0.97
2160 587 0.38 633 0.44 690 0.52 740 0.61 784 0.68 825 0.76 865 0.85 904 0.95 943 1.04 981 1.13
2400 643 0.51 682 0.58 732 0.65 781 0.75 825 0.84 864 0.92 902 1.01 938 1.11 974 1.21 1010 1.32(b)
2640 700 0.66 736 0.74 775 0.81 822 0.90 866 1.01 906 1.11 942 1.20 976 1.29 1009 1.40 1042 1.51
2880 756 0.84 790 0.93 823 1.01 864 1.09 907 1.20 947 1.32 983 1.43 1017 1.53 1048 1.62 1080 1.73
2-hp Oversized Motor & Drive
Continued
External Static Pressure (Inches of Water)
1.10 1.20 1.30 1.40 1.50 1.60 1.70 1.80 1.90 2.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
1-hp Standard Motor & Drive 1-hp Standard Motor & High Static Drive Kit (or 2-hp Oversized Motor & Drive)
1920 996 1.06 1033 1.16 1067 1.25 1102 1.35 1134 1.44 1165 1.53 1195 1.63 1223 1.72 1251 1.82 1277 1.91
2160 1018 1.23 1054 1.32 1090 1.42 1123 1.52 1156 1.63 1188 1.73 1218 1.84 1247 1.94 1276 2.05 1304 2.16
2400 1044 1.42 1079 1.52 1112 1.62 1145 1.73 1177 1.83 1208 1.94 1240 2.06 1268 2.17 1298 2.29 — —
2640 1075 1.62 1107 1.74 1139 1.85 1170 1.96 1201 2.08 1232 2.19 — — — — — — — —
2880 1111 1.85 1140 1.97 1169 2.09 1200 2.22 — — — — — — — — — — — —
2-hp Oversized Motor & Drive 2-hp Oversized Motor & Field Supplied High Static Drive(c)
Notes:
1. For Standard Evaporator Fan Speed (rpm), reference Table 8, p. 12.
2. Data includes pressure drop due to standard filters and wet coils. No accessories or options are included in pressure drop data.
3. Refer to Table 12, p. 12 to determine additional static pressure drop due to other options/accessories.
4. 1-hp Fan Motor Heat (MBh) = 2.829 x Fan bhp + .4024. 2-hp Fan Motor Heat (MBh) = 3.000 x Fan bhp + .5000.
5. Factory supplied motors, in commercial equipment, are definite purpose motors, specifically designed and tested to operate reliably and continuously
at all cataloged conditions. Using the full horsepower range of our fan motors as shown in our tabular data will not result in nuisance tripping or
premature motor failure. Our product's warranty will not be affected.
(a)Field Supplied Fan Sheave AK84 and Belt AX36 required.
(b)1-hp Standard Motor & High Static Drive (or 2-hp Oversized Motor)
(c) Field Supplied Fan Sheave AK56 and Belt AX30 required.

Evaporator Fan Performance
10 RT-SVF25C-EN
Table 6. Belt drive evaporator fan performance - 6 tons standard efficiency with gas heat - YSC072F3,4,W*H high heat
downflow airflow
External Static Pressure (Inches of Water)
0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
1-hp Standard Motor & Field Supplied Low Static Drive(a) 1-hp Standard Motor & Drive
1920 — — 574 0.34 631 0.41 681 0.48 727 0.55 771 0.63 814 0.71 853 0.79 892 0.87 928 0.95
2160 562 0.36 616 0.44 671 0.52 719 0.60 763 0.68 805 0.76 845 0.84 884 0.93 921 1.02 957 1.11
2400 612 0.48 662 0.56 711 0.65 759 0.74 802 0.83 842 0.91 879 1.00 916 1.09 951 1.19 986 1.29
2640 663 0.63 709 0.71 754 0.80 798 0.90 842 1.00 881 1.10 917 1.19 951 1.29 986 1.39 1018 1.49(b)
2880 715 0.80 758 0.88 799 0.98 840 1.08 880 1.19 920 1.30 955 1.41 990 1.51 1022 1.62 1053 1.72
2-hp Oversized Motor & Drive
Continued
External Static Pressure (Inches of Water)
1.10 1.20 1.30 1.40 1.50 1.60 1.70 1.80 1.90 2.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
1-hp Standard Motor & Drive 1-hp Standard Motor & High Static Drive Kit (or 2-hp Oversized Motor & Drive)
1920 963 1.04 997 1.12 1028 1.20 1061 1.28 1090 1.36 1119 1.45 1149 1.54 1177 1.63 1203 1.71 1229 1.80
2160 990 1.21 1023 1.30 1055 1.39 1086 1.48 1115 1.57 1144 1.66 1173 1.76 1200 1.85 1227 1.95 1253 2.04
2400 1019 1.39 1051 1.49 1083 1.60 1113 1.70 1141 1.80 1171 1.90 1199 2.01 1225 2.10 1252 2.20 — —
2640 1050 1.59 1081 1.70 1111 1.81 1141 1.93 1170 2.04 1198 2.15 1226 2.27 — — — — — —
2880 1084 1.83 1114 1.94 1143 2.06 1172 2.18 1199 2.30 ——————— — — —
2-hp Oversized Motor & Drive
Notes:
1. For Standard Evaporator Fan Speed (rpm), reference Table 8, p. 12.
2. Data includes pressure drop due to standard filters and wet coils. No accessories or options are included in pressure drop data.
3. Refer to Table 12, p. 12 to determine additional static pressure drop due to other options/accessories.
4. 1-hp Fan Motor Heat (MBh) = 2.829 x Fan bhp + .4024. 2-hp Fan Motor Heat (MBh) = 3.000 x Fan bhp + .5000
5. Factory supplied motors, in commercial equipment, are definite purpose motors, specifically designed and tested to operate reliably and continuously
at all cataloged conditions. Using the full horsepower range of our fan motors as shown in our tabular data will not result in nuisance tripping or
premature motor failure. Our product's warranty will not be affected.
(a)Field Supplied Fan Sheave AK84 and Belt AX36 required.
(b)1-hp Standard Motor & High Static Drive Kit (or 2-hp Oversized Motor)

Evaporator Fan Performance
RT-SVF25C-EN 11
Table 7. Belt drive evaporator fan performance - 6 tons standard efficiency with gas heat - YSC072F3,4,W*H high heat
horizontal airflow
External Static Pressure (Inches of Water)
0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
1-hp Standard Motor & Field Supplied Low Static Drive(a) 1-hp Standard Motor & Drive
1920 565 0.31 627 0.39 680 0.46 727 0.52 772 0.61 816 0.69 859 0.77 902 0.86 942 0.94 981 1.03
2160 621 0.43 677 0.50 729 0.59 774 0.66 816 0.74 856 0.83 895 0.93 934 1.02 973 1.11 1009 1.21(b)
2400 680 0.57 729 0.65 778 0.74 823 0.84 862 0.92 900 1.00 936 1.10 972 1.20 1006 1.31 1041 1.41
2640 741 0.75 782 0.82 828 0.92 872 1.03 911 1.13 947 1.21 981 1.31 1014 1.41 1048 1.53 1079 1.64
2880 802 0.95 837 1.04 880 1.13 921 1.24 960 1.36 995 1.47 1028 1.56 1060 1.66 1091 1.77 1122 1.89
2-hp Oversized Motor & Drive
Continued
External Static Pressure (Inches of Water)
1.10 1.20 1.30 1.40 1.50 1.60 1.70 1.80 1.90 2.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
1-hp Standard Motor & High Static Drive Kit (or 2-hp Oversized Motor & Drive)
1920 1018 1.12 1054 1.21 1089 1.31 1122 1.40 1154 1.50 1184 1.59 1212 1.69 1241 1.78 1268 1.88 1293 1.97
2160 1045 1.30 1081 1.40 1114 1.50 1149 1.61 1181 1.71 1211 1.81 1241 1.92 1270 2.03 1298 2.13 1324 2.24
2400 1076 1.51 1110 1.62 1143 1.72 1176 1.83 1206 1.94 1238 2.05 1267 2.16 1297 2.28 — — — —
2640 1111 1.75 1144 1.87 1174 1.98 1205 2.09 1236 2.21 — — — — — — — — — —
2880 1151 2.02 1180 2.14 1209 2.27 — — — — — — — — — — — — — —
2-hp Oversized Motor & Drive 2-hp Oversized Motor & Field Supplied High Static Drive(c)
Notes:
1. For Standard Evaporator Fan Speed (rpm), reference Table 8, p. 12.
2. Data includes pressure drop due to standard filters and wet coils. No accessories or options are included in pressure drop data.
3. Refer to Table 12, p. 12 to determine additional static pressure drop due to other options/accessories.
4. 1-hp Fan Motor Heat (MBh) = 2.829 x Fan bhp + .4024. 2-hp Fan Motor Heat (MBh) = 3.000 x Fan bhp + .5000.
5. Factory supplied motors, in commercial equipment, are definite purpose motors, specifically designed and tested to operate reliably and continuously
at all cataloged conditions. Using the full horsepower range of our fan motors as shown in our tabular data will not result in nuisance tripping or
premature motor failure. Our product's warranty will not be affected.
(a)Field Supplied Fan Sheave AK84 and Belt AX36 required.
(b)1-hp Standard Motor & High Static Drive Kit (or 2-hp Oversized Motor).
(c) Field Supplied Fan Sheave AK56 and Belt AX30 required.

12 RT-SVF25C-EN
Performance Data
Table 8. Standard motor & sheave/fan speed (rpm)
Unit Model Fan 6 Turns 5 Turns 4 Turns 3 Turns 2 Turns 1 Turn
Tons Number Sheave Open Open Open Open Open Open Closed
6 T/YSC072F AK64x1” N/A 723 779 835 890 946 1002
Note: Factory set at 3 turns open.
Table 9. Oversized motor & drive sheave/fan speed (rpm)
Unit Model 6 Turns 5 Turns 4 Turns 3 Turns 2 Turns 1 Turn
Tons Number Open Open Open Open Open Open Closed
6 T/YSC072F AK56x1” N/A 958 1022 1086 1150 1214
Notes: Factory set at 3 turns open.
* Indicates both standard and high efficiency units and both ReliaTel™ and Electromechanical controls.
Table 10. Oversized motor & high static drive sheave/fan speed (rpm)
Unit Model 6 Turns 5 Turns 4 Turns 3 Turns 2 Turns 1 Turn
Tons Number Open Open Open Open Open Open Closed
6 T/YSC072F AK54x1” N/A 995 1061 1128 1194 1261
Notes: Factory set at 3 turns open.
* Indicates both standard and high efficiency units and both ReliaTel™ and Electromechanical controls.
Table 11. Outdoor sound power level - dB (ref. 10 - 12 W)
Unit Model Octave Center Frequency Overall
Tons Number 63 125 250 500 1000 2000 4000 8000 dBA
6 T/YSC072F 91 95 90 87 84 79 75 68 89
Note: Tests follow ARI270-95.
Table 12. Static pressure drop through accessories (inches water column) - 3-10 tons
Economizer with OA/RA Dampers(a) Electric Heater
Accessory (kW)(b),(c)
Unit Model Standard 2" MERV 82" MERV 13 100% OA 100% RA 100% OA 100% RA 100% OA 100% RA 5-6 9-18 23-36 54
Tons Number cfm Filters(d) Filter Filter Downflow Low Leak(e) Horizontal
6 T/YSC072F 1920 0.04 0.07 0.10 0.10 0.01 0.20 0.09 0.06 0.02 — 0.01 0.02 —
6 T/YSC072F 2400 0.06 0.09 0.13 0.11 0.02 0.31 0.11 0.08 0.02 — 0.02 0.03 —
6 T/YSC072F 2880 0.09 0.12 0.15 0.13 0.04 0.46 0.19 0.10 0.04 — 0.03 0.05 —
(a)OA = Outside Air and RA = Return Air.
(b)Nominal kW ratings at 240, 480, 600 volts. Heaters only available on T units.
(c) Electric heaters restricted on applications below 320 cfm/Ton.
(d)Tested with standard filters. Difference in pressure drop should be considered when utilizing optional 2” MERV 8 and MERV 13 filters.
(e) Low Leak - Downflow only.

RT-SVF25C-EN 13
Electrical Data
Table 13. Unit wiring - standard efficiency
Standard Indoor Fan Motor(a) Oversized Indoor Fan Motor
Tons Unit Model Number Voltage Range MCA
Max Fuse Size
or Max Circuit
Breaker MCA
Max Fuse Size
or Max Circuit
Breaker
6 T/YSC072F3 187-253 36.5 50 37.8 60
6 T/YSC072F4 414-506 18.2 25 19.4 25
6 T/YSC072FW 517-633 12.7 20 13.5 20
(a)Belt Drive Motor.
Table 14. Unit wiring with electric heat (single point connection) - standard efficiency
Standard Indoor Motor(a) Oversized Indoor Motor
Tons Unit Model Number Heater Model Number Heater kW Rating Control Stages MCA
Max Fuse Size or
Max Circuit
Breaker MCA
Max Fuse Size or
Max Circuit
Breaker
208/230 Volts Three Phase
6 TSC072F3 BAYHTRS309* 6.8/9.0 1 36.5/36.5 50/50 37.8/37.8 60/60
6 TSC072F3 BAYHTRS318* 13.5/18.0 1 53.1/60.4 60/70 54.8/62.0 60/70
6 TSC072F3 BAYHTRS327* 20.3/27.0 2 76.6/87.5 80/90 78.3/89.1 80/90
6 TSC072F3 BAYHTRS336* 27.0/36.0 2 100.1/114.5 110/125 101.8/116.1 110/125
460 Volts Three Phase
6 TSC072F4 BAYHTRS409* 9.0 1 18.2 25 19.3 25
6 TSC072F4 BAYHTRS418* 18.0 1 30.3 35 31.6 35
6 TSC072F4 BAYHTRS427* 27.0 2 43.8 45 45.1 50
6 TSC072F4 BAYHTRS436* 36.0 2 57.3 60 58.6 60
575 Volts Three Phase
6 TSC072FW BAYHTRSW09* 9.0 1 13.0 20 14.0 20
6 TSC072FW BAYHTRSW18* 18.0 1 23.8 25 24.8 25
6 TSC072FW BAYHTRSW27* 27.0 2 34.6 35 35.6 40
6 TSC072FW BAYHTRSW36* 36.0 2 45.4 50 46.4 50
(a)Belt Drive Motor.
Table 15. Electrical characteristics - compressor motor and condenser motor - 60 cycle - standard efficiency
Compressor Motors Condenser Fan Motors
Unit Model Amps(a) Amps(a)
Tons Number No. Volts Phase hp(b) rpm RLA LRA No. Volts Phase hp FLA LRA
6 T/YSC072F3 1 208-230 3 5.6 3500 22.4 149.0 1 208-230 1 .70 3.5 10.9
6 T/YSC072F4 1 460 3 5.6 3500 10.6 75.0 1 460 1 .70 2.4 6.6
6 T/YSC072FW 1 575 3 5.6 3500 7.7 54.0 1 575 1 .70 1.4 3.6
(a)Amp draw for each motor; multiply value by number of motors to determine total amps.
(b)hp for each compressor.

Electrical Data
14 RT-SVF25C-EN
Table 16. Electrical characteristics - standard evaporator fan motor - 60 cycle - belt drive standard efficiency
Unit Model Amps
Tons Number No. Volts Phase hp FLA LRA
6 T/YSC072F3 1 208-230 3 1.00 5.0 32.2
6 T/YSC072F4 1 460 3 1.00 2.5 16.1
6 T/YSC072FW 1 575 3 1.00 1.7 13.2
Table 17. Electrical characteristics - oversized evaporator fan motor - 60 cycle - belt drive - standard efficiency
Unit Model Amps
Tons Number No. Volts Phase hp FLA LRA
6 T/YSC072F3 1 208-230 3 2.00 6.30 48.0
6 T/YSC072F4 1 460 3 2.00 3.6 24.0
6 T/YSC072FW 1 575 3 2.00 2.50 18.2
Table 18. Electrical characteristics — power exhaust (cooling and gas/electric)
Tons Volts Phase hp rpm FLA LRA
6 208-230 1 0.87 1075(a) 5.7 13.6
6 460 1 0.87 1075(a) 3.3 6.8
6 575 1 0.87 1075(a) 2.3 5.4
(a)Two speed.
Table 19. Electrical characteristics - inducer motor
Unit Model Number Stages hp rpm Volts Phase LRA
YSC072F**(L,M,X,Y) 1 1/35 3000 208-230 1 0.6
YSC072F**(H,Z) 2 1/15 2800/3350 208-230 1 0.4

RT-SVF25C-EN 15
Sequence of Operation
These units are offered with two control options,
electromechanical and ReliaTel™.
Note: Refer to the unit nameplate: If the 9th digit of the
model number = R, proceed with the following
Sequence of Operation. If the 9th digit of the model
number = E, proceed with “Electromechanical
Controls,” p. 18.
Note: The Condensate Overflow Switch (COF) (optional)
will shut the unit down if the float is raised and the
switch is closed.
ReliaTel Controls
ReliaTel Control is a microelectronic control feature, which
provides operating functions that are significantly
different than conventional electromechanical units.The
master module is the ReliaTel Refrigeration Module
(RTRM).
The RTRM provides compressor anti-short cycle timing
functions through minimum “Off” and “On” timing to
increase reliability, performance and to maximize unit
efficiency.
Upon power initialization, the RTRM performs self-
diagnostic checks to insure that all internal controls are
functioning. It checks the configuration parameters
against the components connected to the system.
The LED located on the RTRM module is turned “On”
within one second after power-up if all internal operations
are okay.
ReliaTel Control Cooling without an
Economizer
When the system switch is set to the “Cool” position and
the zone temperature rises above the cooling setpoint
control band, the RTRM energizes the (K9) relay coil
located on the RTRM. When the K9 relay contacts close,
the compressor contactor (CC1) coil is energized provided
the low pressure control (LPC1), high pressure control
(HPC1) and discharge line thermostat (TDL 1) are closed.
When the CC1 contacts close, compressor (CPR1) and the
outdoor fan motor (ODM) start to maintain the zone
temperature to within ± 2ºF of the sensor setpoint at the
sensed location.
If the first stage of cooling can not satisfy the cooling
requirement, the RTRM energizes the (K10) relay coil
located on the RTRM.When the (K10) relay contacts close,
the compressor contactor (CC2) coil is energized provided
the low pressure control (LPC2), high pressure control
(HPC2) and discharge line thermostat (TDL 2) are closed.
When the CC2 contacts close, compressor (CPR2) starts to
maintain the zone temperature to within ± 2ºF of the sensor
setpoint at the sensed location.
Three-Stages of Cooling1
When the unit is configured for three-stage cooling, and
the system switch is set to the cool position and the zone
temperature rises above the cooling setpoint control band,
the RTRM energizes the (K10) relay coil located on the
RTRM. When the (K10) relay contacts close, compressor
contactor (CC2) is energized.This is the smaller of the two
compressors (CPR2).This staging order is opposite
standard staging order.
If the first stage of cooling can not satisfy the cooling
requirement, the RTRM energizes the (K9) relay coil and
de-energizes the (K10) relay coil on the RTRM. Compressor
contactor (CC1) is energized, bringing on the larger of the
two compressors (CPR1). Compressor contactor (CC2) is
de-energized, turning off the smaller compressor.
If the second stage of cooling can not satisfy the cooling
requirement, the RTRM keeps the (K9) relay coil energized
and energizes the (K10) relay coil. Compressor contactors
(CC1) and (CC2) are energized, and both compressors
(CPR1 and CPR2).
Lead/Lag is disabled with three-stage cooling. A unit
configured for three-stage cooling and controlled with a
thermostat will operate as a two-stage unit.
ReliaTel Control Evaporator Fan Operation
(for Gas Units)
When the fan selection switch is set to the “Auto” position,
the RTRM energizes the (K6) relay coil approximately 1
second after energizing the compressor contactor coil
(CC1) in the cooling mode. In the heating mode, the RTRM
energizes the (K6) relay coil approximately 45 second after
gas ignition. Closing the (K6) contacts on the RTRM
energizes the indoor fan relay (F) coil to start the indoor fan
motor (IDM).
The RTRM de-energizes the fan relay (F) approximately 60
seconds after the cooling requirement has be satisfied to
enhance unit efficiency. When the heating cycle is
terminated, the indoor fan relay (F) coil is de-energized
approximately 90 seconds after the heating requirement.
When the fan selection switch is set to the “On” position,
the RTRM keeps the indoor fan relay coil (F) energized for
continuous fan motor operation.
When the unit is equipped with the optional clogged filter
switch, wired between terminals J7-3 and J7-4 on the
ReliaTel Options Module (RTOM), the RTRM produces an
analog output if the clogged filter switch (CFS) closes for
two minutes after a request for fan operation. When the
1High efficiency units only.

16 RT-SVF25C-EN
Sequence of Operation
system is connected to a remote panel, the “SERVICE”
LED will be turned on when this failure occurs.
ReliaTel Control Evaporator Fan Operation
(for Cooling Only Units)
When the fan selection switch is set to the “Auto” position,
the RTRM energizes the (K6) relay coil approximately 1
second after energizing the compressor contactor coil
(CC1) in the cooling mode. In the heating mode, the RTRM
energizes the (K6) relay coil approximately 1 second
before energizing the electric heat contactors. Closing the
(K6) contacts on the RTRM energizes the indoor fan relay
(F) coil to start the indoor fan motor (IDM).The RTRM de-
energizes the fan relay (F) approximately 60 seconds after
the cooling requirement has be satisfied to enhance unit
efficiency.
When the heating cycle is terminated, the indoor fan relay
(F) coil is de-energized at the same time as the heater
contactors.
When the fan selection switch is set to the “On” position,
the RTRM keeps the indoor fan relay coil (F) energized for
continuous fan motor operation.
When the unit is equipped with the optional clogged filter
switch, wired between terminals J7-3and J7-4 on the
ReliaTel Options Module (RTOM), the RTRM produces an
analog output if the clogged filter switch (CFS) closes for
two minutes after a request for fan operation.
When the system is connected to a remote panel, the
“SERVICE” LED will be turned on when this failure occurs.
Low Ambient Operation
During low ambient operation, outside air temperature
below 55°F, the RTRM will cycle the compressor and
outdoor fan motor “Off” for approximately 3 minutes after
every 10 minutes of accumulated compressor run time.
The indoor fan motor (IDM) will continue to operate during
this evaporator defrost cycle (EDC) and the compressor
and outdoor fan will return to normal operation once the
defrost cycle has terminated and the compressor “Off”
time delay has been satisfied.
Note: (For units with the dehumidification option) When
in dehumidification mode, the unit will not cycle as
described above.The unit will run continuously in
dehumidification mode at all ambient conditions
above 40ºF. Dehumidification is disabled at
ambient conditions below 40ºF.
ReliaTel Control Dehumidification
Single Compressor Units
On a call for dehumidification, the reheat valve is
energized and the compressor is turned on. When the
humidity control setpoint is satisfied, the valve is de-
energized and the compressor is turned off. If there is a call
for cooling or heating from the space temperature
controller, i.e. zone sensor or thermostat, while in reheat,
the reheat valve is de-energized and the compressor
continues to run, or the heat is turned on.The 3 minute
compressor on and off times are still active during
compressor operation.
Dual Compressor Units
The dehumidification cycle is only permitted above 40ºF as
indicated above and is not permitted during a heating
cycle or during a demand for 2nd stage cooling. Otherwise,
when an installed zone humidity sensor indicates a
relative humidity equal to or greater than the RH set point
as adjusted on the ReliaTel Options Module (RTOM), a
dehumidification cycle is initiated.The Sequence of
Operation for the dehumidification cycle is identical to that
of the second stage ReliaTel cooling cycle, except that the
hot gas reheat valve (RHV) is energized, allowing air from
the evaporator to be reheated. Also, any installed fresh air
damper is driven to minimum position.The
dehumidification cycle is terminated by initiation of a
heating cycle or a 2nd stage cooling cycle or when zone
humidity is reduced to 5% below the R.H. set point. In the
absence of a zone humidity sensor input, an on/off input
from a zone humidistat is used to initiate/terminate the
dehumidification cycle.
Dehumidification takes priority over a call for one-stage
cooling.
Heating or two-stage cooling takes priority over
dehumidification, and a relative humidity sensor takes
priority over a humidistat.
Dehumidification Coil Purge Cycle
On multiple circuit units with dehumidification/reheat
configured, a purge cycle will be active for compressor
reliability.The purpose of this function is to properly
distribute refrigerant and lubricant throughout the system
by temporarily switching to the unused section of the coil
for 3 minutes (purge cycle).The function operates as
follows:
1. A purge cycle will be initiated after 90 minutes of
accumulated compressor run time in only one mode:
cooling or dehumidification, without transitioning to
the other mode.
2. A purge cycle will consist of transitioning to the mode
that hasn’t run in 90 minutes of total compressor
operation.The cycle will last for a period of 3 minutes.
3. The 90-minute cycle count will be reset anytime there
is a normal transition between cooling and
dehumidification.Transitioning from one of these
modes to any other mode (off or heat) will not reset the
counter.
4. If the purge cycle is a cooling cycle, only the first circuit
will be activated. If it is a dehumidification cycle then
the normal 2-compressor dehumidification mode
cycle will be used.
5. The purge cycle will ignore the low ambient
dehumidification lockout feature.

RT-SVF25C-EN 17
Sequence of Operation
6. A purge cycle takes priority over normal cooling or
dehumidification requests, but will discontinue for all
high priority lockouts and alarms.
ReliaTel Control Cooling with
an Economizer
The economizer is utilized to control the zone temperature
providing the outside air conditions are suitable. Outside
air is drawn into the unit through modulating dampers.
When cooling is required and economizing is possible, the
RTRM sends the cooling request to the unit economizer
actuator (ECA) to open the economizer damper.The RTRM
tries to cool the zone utilizing the economizer to slightly
below the zone temperature setpoint. If the mixed air
sensor (MAS) senses that the mixed air temperature is
below 53°F, the damper modulates toward the closed
position. If the zone temperature continues to rise above
the zone temperature setpoint control band and the
economizer damper is full open for 5 minutes, the RTRM
energizes the compressor contactor (CC1). If the zone
temperature continues to rise above the zone temperature
setpoint control band and the economizer damper is fully
open, the RTRM energizes the compressor contactor
(CC2).
The ECA continues to modulate the economizer damper
open/closed to keep the mixed air temperature that is
calculated by the RTRM.
If economizing is not possible, the ECA drives the damper
to the minimum position setpoint when the indoor fan
relay (F) is energized and allows mechanical cooling
operation.
When the unit is equipped with the optional fan failure
switch, wired between terminals J7-5 and J7-6 on the
RTOM, the RTRM will stop all cooling functions and
produce an analog output if the fan failure switch (FFS)
does not open within 40 seconds after a request for fan
operation. When the system is connected to a remote
panel, the “SERVICE” LED will flash when this failure
occurs.
Note: For units equipped with the dehumidification
option, if the unit is economizing, the damper
resets to minimum position while in
dehumidification mode.
Economizer Set-Up
Adjusting the minimum position potentiometer located on
the unit economizer actuator (ECA) sets the required
amount of ventilation air.
Two of the three methods for determining the suitability of
the outside air can be selected utilizing the enthalpy
potentiometer on the ECA, as described below:
1. AmbientTemperature - controlling the economizing
cycle by sensing the outside air dry bulb temperature.
Table 20, p. 17 lists the selectable dry bulb values by
potentiometer setting.
2. Reference Enthalpy - controlling the economizer cycle
by sensing the outdoor air humidity. Table 20, p. 17
lists the selectable enthalpy values by potentiometer
setting. If the outside air enthalpy value is less than the
selected value, the economizer is allowed to operate.
3. Comparative Enthalpy - utilizing a humidity sensor and
a temperature sensor in both the return air stream and
the outdoor air stream, the unit control processor
(RTRM) will be able to establish which conditions are
best suited for maintaining the zone temperature, i.e.
indoor conditions or outdoor conditions.The
potentiometer located on the ECA is non-functional
when both the temperature and humidity sensors are
installed.
ReliaTel Control Heating Operation (for
Cooling Only Units)
When the system switch is set to the “Heat” position and
the zone temperature falls below the heating setpoint
control band, the RTRM energizes (K1) relay coil.When the
(K1) relay contacts close, located on the RTRM, the first
stage electric heat contactor (AH or AH & CH) is energized.
If the first stage of electric heat can not satisfy the heating
requirement, the RTRM energizes (K2) relay coil.When the
(K2) relay contacts close, located on the RTRM, the second
stage electric heat contactor (BH) is energized, if
applicable.The RTRM cycles both the first and second
stages of heat “On” and “Off” as required to maintain the
zone temperature setpoint.
ReliaTel Control Heating Operation (for
Gas Units)
When the system switch is set to the “Heat” position and
the zone temperature falls below the heating setpoint
control band, a heat cycle is initiated when the RTRM
communicates ignition information to the Ignition module
(IGN).
Ignition Module
Two-stage (IGN) runs self-check (including verification that
the gas valve is de-energized). (IGN) checks the high-limit
switches (TC01 &TC02) for normally closed contacts, the
pressure switch (PS) for normally open contacts, and the
flame rollout (FR) switch for continuity. (IGN) energizes
inducer blower on high speed to check pressure switch
closure. If the pressure switch is closed, the inducer blower
Table 20. Potentiometer settings
Potentiometer
Setting Dry Bulb Reference Enthalpy
A 73°F (22.8ºC) 27 Btu/lb (63 kJ/kg)
B 70°F (21.1ºC) 25 Btu/lb (58 kJ/kg)
C 67°F(a) (19.4ºC)
(a)Factory settings
23 Btu/lb (53 kJ/kg)
D 63°F (17.2ºC) 22 Btu/lb (51 kJ/kg)
E 55ºF (12.8ºC) 19 Btu/lb (44 kJ/kg)

18 RT-SVF25C-EN
Sequence of Operation
starts a 20-second pre-purge (15 seconds on high speed
followed by 5 seconds on low speed). If the pressure
switch (PS) is still open, the inducer blower will continue to
be energized on high speed until pressure switch closure.
After pre-purge completes, the (IGN) energizes the first
stage of the gas valve, initiates spark for 2 seconds
minimum, 7 seconds maximum (ignition trial) and detects
flame and de-energizes spark. From this point, a fixed 45
second indoor blower delay on timing starts. After the
indoor blower delay on is completed, the (IGN) energizes
the indoor blower.The (IGN) enters a normal operating
loop where all inputs are continuously monitored. If the
first stage of gas heat can not satisfy the heating
requirement, the thermostat closes W2.The (IGN)
energizes the second stage of the gas valve and the second
stage of inducer blower. When the zone thermostat is
satisfied, the (IGN) de-energizes the gas valve.The (IGN)
senses loss of flame.The (IGN) initiates a 5 second inducer
blower post purge.The (RTRM) initiates a second indoor
blower delay off.
If the burner fails to ignite, the ignition module will attempt
two retries before locking out.The green LED will indicate
a lock out by two fast flashes. An ignition lockout can be
reset by;
1. Opening for 3 seconds and closing the main power
disconnect switch.
2. Switching the “Mode” switch on the zone sensor to
“OFF” and then to the desired position.
3. Allowing the ignition control module to reset
automatically after one hour. Refer to the “Ignition
Control Module Diagnostics” section for the LED
diagnostic definitions.
When the fan selection switch is set to the “Auto” position,
the RTRM energizes the indoor fan relay (F) coil
approximately 30 second after initiating the heating cycle
to start the indoor fan motor (IDM).
Drain Pan Condensate Overflow Switch
(Optional)
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 function 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 the unit to
shutdown more than 2 times in a 3 day period, the unit will
be locked-out of operation. A manual reset of the
diagnostic system through the zone sensor or Building
Automation System (BAS) will be required. Cycling unit
power will also clear the fault.
Electromechanical Controls
These units are offered with two control options,
electromechanical and ReliaTel controls.The ReliaTel
controls is a microelectronic control feature, which
provides operating functions that are significantly
different than conventional electromechanical units.
Electromechanical Control Cooling
without an Economizer
When the thermostat switch is set to the “Cool” position
and the zone temperature rises above the cooling setpoint,
the thermostatY contacts close.The compressor
contactor (CC1) coil is energized provided the low pressure
control (LPC1), high pressure control (HPC1) and
discharge line thermostat (TDL 1) are closed. When the
(CC1) contacts close, compressor (CPR1) and the outdoor
fan motor (ODM) start. If the first stage of cooling can not
satisfy the cooling requirement, the thermostat closesY2.
The compressor contactor (CC2) coil is energized provided
the low pressure control (LPC2), high pressure control
(HPC2) and discharge line thermostat (TDL 2) are closed.
When the (CC2) contacts close, compressor (CPR2) starts.
Electromechanical Control Evaporator Fan
Operation (for Gas Units)
When the thermostat fan selection switch is set to the
“Auto” position, the Ignition Module (IGN) energizes the
indoor fan relay (F) approximately 1 second after
energizing the compressor contactor coil (CC1) in the
cooling mode. In the heating mode, the Ignition Module
(IGN) energizes the indoor fan relay (F) coil approximately
45 second after gas ignition. Closing indoor fan relay (F)
coil starts the indoor fan motor (IDM).The (IGN) de-
energizes the fan relay (F) approximately 80 seconds after
the cooling requirement has been satisfied to enhance unit
efficiency.
When the heating cycle is terminated, the indoor fan relay
(F) coil is de-energized approximately 90 seconds after the
heating requirement.
Table 21. Ignition module diagnostics
Steady light Module is powered up, but no active call for
heat.
Blinking at
continuous
steady rate Active call for heat.
One blink Loss of communication.
Two blinks System lockout (failure to ignite, no spark, low/
no gas pressure, etc.)
Three blinks Pressure switch (no vent air flow, bad CBM,
closed at initial call for heat). Auto reset.
Four blinks High limit (excessive heat in combustion
chamber, low airflow). Auto reset.
Five blinks Flame sensed and gas valve not energized or
flame sensed and no call for heat.
Six blinks
Flame rollout (CBM failure, incorrect gas
pressure, incorrect primary air). Requires
manual reset of the switch.
Seven blinks ReliaTel module will communicate a heat fail
diagnostic back to the RTRM.

RT-SVF25C-EN 19
Sequence of Operation
When the thermostat fan selection switch is set to the“On”
position, the (IGN) keeps the indoor fan relay coil (F)
energized for continuous fan motor operation.
Electromechanical Evaporator Fan
Operation (for Cooling Only Units)
When the thermostat fan selection switch is set to the
“Auto” position, the thermostat energizes the indoor fan
relay coil (F) to start the indoor fan motor (IDM).The fan
relay (F) de-energizes after the cooling requirement has
been satisfied. When the heating cycle is terminated, the
indoor fan relay (F) coil is de-energized with heater
contactors.
When the thermostat fan selection switch is set to the“On”
position, the thermostat keeps the indoor fan relay coil (F)
energized for continuous fan motor operation.
Economizer Set-Up
Adjusting the minimum position potentiometer located on
the unit economizer actuator (ECA) sets the required
amount of ventilation air.
Ambient temperature is controlling the economizing cycle
by sensing the outside air dry bulb temperature. Table 20,
p. 17 lists the selectable dry bulb values by potentiometer
setting.
Electromechanical Control Cooling with
an Economizer
The economizer is utilized to control the zone temperature
providing the outside air conditions are suitable. Outside
air is drawn into the unit through modulating dampers.
When cooling is required and economizing is possible, the
unit economizer actuator (ECA) opens the economizer
damper.The ECA continues to modulate the economizer
damper open/closed to keep the mixed air temperature in
the 50ºF to 55ºF range.
The thermostat will close theY2 contacts to turn on
contactor (CC1) if mechanical cooling is required.
If economizing is not possible, the ECA drives the damper
to the minimum position setpoint when the indoor fan
relay (F) is energized and allows mechanical cooling
operation.
Electromechanical Control Heating
Operation (for Cooling Only Units)
When the system switch is set to the “Heat” position and
the zone temperature falls below the heating setpoint, the
thermostat closes W1 contacts the first stage electric heat
contactor (AH or AH & CH) is energized. If the first stage of
electric heat can not satisfy the heating requirement, the
thermostat closes W2.
When theW2 contacts close, the second stage electric heat
contactor (BH) is energized, if applicable.The thermostat
cycles both the first and second stages of heat “On” and
“Off” as required to maintain the zone temperature
setpoint.
Electromechanical Control Heating
Operation (for Gas Units)
When the system switch is set to the “Heat” position and
the zone temperature falls below the heating setpoint, the
Ignition module (IGN) initiates a heat cycle.
Ignition Module Low, Medium and
High Heat
Two-stage (IGN) runs self-check (including verification that
the gas valve is de-energized). (IGN) checks the high-limit
switches (TC01 &TC02) for normally closed contacts, the
pressure switch (PS) for normally open contacts, and the
flame rollout (FR) switch for continuity. (IGN) energizes
inducer blower on high speed to check pressure switch
closure.
If the pressure switch is closed, the inducer blower starts
a 20 second pre-purge (15 seconds on high speed followed
by 5 seconds on low speed).
If the pressure switch (PS) is still open, the inducer blower
will continue to be energized on high speed until pressure
switch closure.
After pre-purge completes, the (IGN) energizes the first
stage of the gas valve, initiates spark for 2 seconds
minimum, 7 seconds maximum (ignition trial) and detects
flame and de-energizes spark. From this point, a fixed 45
second indoor blower delay on timing starts.
After the indoor blower delay on is completed, the (IGN)
energizes the indoor blower. The (IGN) enters a normal
operating loop where all inputs are continuously
monitored. If the first stage of gas heat can not satisfy the
heating requirement, the thermostat closes W2.The (IGN)
energizes the second stage of the gas valve and the second
stage of inducer blower.
When the zone thermostat is satisfied, the (IGN) de-
energizes the gas valve.The (IGN) senses loss of flame.
The (IGN) initiates a 5 second inducer blower post purge
and 90 second indoor blower delay off at current speed.
The (IGN) de-energizes the inducer blower at the end of the
post purge.The (IGN) de-energizes the indoor blower at
the end of the selected indoor blower delay off.

20 RT-SVF25C-EN
Sequence of Operation
Drain Pan Condensate Overflow Switch
(Optional)
The Condensate Overflow Switch (COF) is utilized to
prevent water overflow from the drain pan.The float
switch is installed on the corner lip of the drain pan. 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 circuit is opened,
a delay timer will prevent unit start-up for three minutes.
Table 22. Ignition module diagnostics
Steady light Module is powered up, but no active call for
heat.
Blinking at
continuous steady
rate Active call for heat.
One blink Loss of communication.
Two blinks System lockout (failure to ignite, no spark,
low/no gas pressure, etc.)
Three blinks Pressure switch (no vent air flow, bad CBM,
closed at initial call for heat). Auto reset.
Four blinks High limit (excessive heat in combustion
chamber, low airflow). Auto reset.
Five blinks Flame sensed and gas valve not energized
or flame sensed and no call for heat.
Six blinks
Flame rollout (CBM failure, incorrect gas
pressure, incorrect primary air). Requires
manual reset of the switch.
Seven blinks W1& W2 swapped (electromechanical 3-10
tons units).