Ingersol Rand Precedent TSC120F 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 and Gas/Electric
10Ton Standard Efficiency Rooftop Units
Service Facts
Model Numbers TSC120F YSC120F
RT-SVF28F-EN
July 2014

© 2014Trane All rights reserved RT-SVF28F-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-SVF28F-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-SVF28F-EN (11 July 2014)
• Added Low Leak Economizer Factory and Field
Installed Option

4 RT-SVF28F-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 ....................... 9
Electrical Data .......................... 10
Sequence of Operation .................. 12
ReliaTel Controls ..................... 12
ReliaTel Control Cooling without an Econo-
mizer ............................. 12
Three-Stages of Cooling ............. 12
ReliaTel Control Evaporator Fan Operation
(for Gas Units) ..................... 12
ReliaTel Control Evaporator Fan Operation
(for Cooling Only Units) .............. 13
Low Ambient Operation .............. 13
ReliaTel Control Dehumidification ..... 13
Dehumidification Coil Purge Cycle ..... 13
ReliaTel Control Cooling with
an Economizer ..................... 14
Economizer Set-Up .................. 14
ReliaTel Control Heating Operation (for Cool-
ing Only Units) ..................... 14
ReliaTel Control Heating Operation (for Gas
Units) ............................. 14
Ignition Module .................... 14
Drain Pan Condensate Overflow Switch (Op-
tional) ............................ 15
VAV Units Only-Sequence of Operation .15
Supply Air Pressure Control .......... 15
Supply Air Static Pressure Limit ....... 15
Supply Air Temperature Controls ...... 15
Supply Air Setpoint Reset ............ 16
Zone Temperature Control ........... 16
Electromechanical Controls ............ 16
Electromechanical Control Cooling without
an Economizer ..................... 16
Electromechanical Control Evaporator Fan
Operation (for Gas Units) .............17
Electromechanical Evaporator Fan Operation
(for Cooling Only Units) ...............17
Economizer Set-Up ..................17
Electromechanical Control Cooling with an
Economizer .........................17
Electromechanical Control Heating Operation
(for Cooling Only Units) ...............17
Electromechanical Control Heating Operation
(for Gas Units) ......................17
Ignition Module Low, Medium and
High Heat ..........................17
Drain Pan Condensate Overflow Switch (Op-
tional) .............................18
Pressure Curves .........................19
Subcooling Charging Chart ...............20
Refrigerant Circuit .......................21

RT-SVF28F-EN 5
General Data
Table 1. General data -10 tons - standard efficiency
10 Tons
T/YSC120F3,4,W
Cooling Performance(a)
Gross Cooling Capacity
EER(b)
Nominal cfm/AHRI Rated cfm
AHRI Net Cooling Capacity
IEER(c)
System Power (kW)
119,000
11.3
4,000/3,500
113,000
13.0
10.0
Compressor
Number/Type 2/Scroll
Sound
Outdoor Sound Rating (dB)(d) 88
Outdoor Coil - Type Microchannel
Configuration
Tube Size (in.) OD
Face Area (sq. ft.)
Rows/FPI
Full Face
1
20.77
1/20
Indoor Coil - Type Lanced
Configuration
Tube Size (in.)
Face Area (sq. ft.)
Rows/FPI
Refrigerant Control
Drain Connection Number/Size (in.)
Intertwined
0.3125
12.36
4/16
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
6,800
0.75
1,100
Indoor Fan - Type BC Plenum
Number Used/Diameter (in.)/Width (in.)
Drive Type/Number Speeds
Motor hp (Standard/Oversized)
1/19.7x15
Direct/Variable(e)
3.75/—
Filters(f)
Type Furnished
Number Size Recommended Throwaway (4) 20x25x2
Refrigerant Charge (g)
Pounds of R-410A 5.5/4.2
Heating Performance(h)
(Gas/Electric Only)
Heating Input
Low Heat Input (Btu)
Mid Heat Input (Btu)
High Heat Input (Btu)
150,000/105,000
200,000/140,000
250,000/175,000
Heating Output
Low Heat Input (Btu)
Mid Heat Input (Btu)
High Heat Input (Btu)
120,000/84,000
160,000/112,000
200,000/140,000
AFUE%(i)
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)
3
4
5
No. Stages
Low Heat Input (Btu)
Mid Heat Input (Btu)
High Heat Input (Btu)
2
2
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
3/4
3/4
3/4
(a)Coolingperformance israted at95°F ambient,80°F entering drybulb,
67°F entering wet bulb. Gross capacity does not include the effect of
fan motor heat. AHRI 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 AHRI Standard
340/360.
(b)EER is rated at AHRI conditions and in accordance with DOE test pro-
cedures.
(c) Integrated Efficiency Ratio (IEER) is rated in accordance with AHRI
Standard 340/360. The IEER rating requires that the unit efficiency
be determined at 100%, 75%, 50% and 25% load (net capacity) at
the specified in AHRI Standard.
(d)Outdoor Sound Rating shown is tested in accordance with AHRI Stan-
dard 270. For additional information refer to Table 10, p. 9.
(e) For multispeed direct drive rpm TSC/YSC values, reference Table 8,
p. 9.
(f) Optional 2” MERV 8 and MERV 13 filters also available.
(g)Refrigerant charge is an approximate value. For a more precise value,
see unit nameplate and service instructions.
(h)Heating performance limit settings and rating data were established
and approved under laboratory test conditions using American Na-
tionalStandardsInstitutestandards.Ratings shownare forelevations
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. Appli-
cable to Gas/Electric units only.
(i) AFUE is rated in accordance with DOE test procedures.
Table 1. General data -10 tons - standard efficiency
10 Tons
T/YSC120F3,4,W

6 RT-SVF28F-EN
Evaporator Fan Performance
Table 2. Direct drive evaporator fan performance - 10 tons standard efficiency - TSC120F3,4,W downflow airflow
External Static Pressure (Inches of Water)
.10 .20 .30 .40 .50 .60 .70 .80 .90 1.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
3200 1028 0.67 1054 0.74 1079 0.81 1105 0.88 1131 0.96 1157 1.04 1184 1.12 1209 1.21 1234 1.30 1258 1.38
3600 1150 0.93 1173 1.01 1196 1.09 1219 1.17 1242 1.25 1265 1.34 1288 1.43 1312 1.52 1335 1.61 1357 1.71
4000 1272 1.25 1294 1.34 1315 1.43 1335 1.52 1356 1.61 1376 1.70 1397 1.80 1418 1.90 1440 2.00 1460 2.09
4400 1395 1.65 1415 1.75 1435 1.84 1453 1.94 1472 2.04 1490 2.14 1509 2.24 1528 2.34 1547 2.45 1566 2.56
4800 1518 2.12 1537 2.23 1555 2.33 1572 2.44 1590 2.54 1606 2.65 1623 2.76 1641 2.87 1657 2.98 1675 3.10
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
3200 1280 1.46 1302 1.54 1324 1.63 1347 1.71 1370 1.80 1392 1.89 1414 1.99 1436 2.09 1458 2.19 1479 2.28
3600 1379 1.80 1401 1.90 1422 2.00 1441 2.09 1461 2.18 1480 2.27 1501 2.36 1521 2.46 1542 2.57 1561 2.67
4000 1481 2.20 1501 2.30 1522 2.41 1542 2.52 1561 2.63 1579 2.73 1597 2.84 1614 2.94 1631 3.04 1649 3.14
4400 1585 2.67 1604 2.78 1623 2.89 1642 3.01 1660 3.12 1679 3.25 1696 3.36 — — — — — —
4800 1693 3.22 — — — — — — — — ——————— — — —
Notes:
1. For Direct Drive Evaporator Fan Speed (rpm), reference Table 8, p. 9.
2. Data includes pressure drop due to standard filters and wet coils.
3. Refer to Table 11, p. 9 to determine additional static pressure drop due to other options/accessories.
4. Direct Drive Fan Motor Heat (MBH) = 2.8623xFan BHP -0.1504
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.
Table 3. Direct drive evaporator fan performance - 10 tons standard efficiency - TSC120F3,4,W horizontal airflow
External Static Pressure (Inches of Water)
.10 .20 .30 .40 .50 .60 .70 .80 .90 1.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
3200 1016 0.65 1044 0.72 1070 0.79 1097 0.87 1123 0.95 1148 1.03 1173 1.10 1197 1.18 1221 1.26 1245 1.34
3600 1137 0.91 1162 0.99 1185 1.07 1209 1.15 1232 1.24 1256 1.32 1279 1.41 1301 1.49 1323 1.58 1344 1.66
4000 1258 1.22 1280 1.31 1302 1.40 1323 1.49 1344 1.58 1366 1.68 1387 1.78 1408 1.87 1428 1.97 1448 2.06
4400 1379 1.60 1400 1.70 1420 1.80 1439 1.90 1459 2.00 1478 2.10 1497 2.21 1517 2.32 1535 2.42 1554 2.52
4800 1501 2.06 1520 2.17 1538 2.28 1557 2.38 1575 2.49 1592 2.60 1609 2.71 1627 2.83 1646 2.94 1663 3.06
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
3200 1269 1.43 1293 1.52 1317 1.61 1339 1.70 1361 1.78 1383 1.87 1404 1.96 1425 2.05 1447 2.14 1468 2.24
3600 1366 1.75 1386 1.84 1408 1.94 1429 2.04 1451 2.15 1472 2.25 1492 2.35 1513 2.45 1532 2.54 1551 003
4000 1467 2.15 1487 2.25 1506 2.34 1525 2.44 1544 2.55 1563 2.65 1582 2.76 1602 2.89 1620 3.00 1639 3.12
4400 1573 2.63 1591 2.73 1609 2.84 1626 2.94 1643 3.04 1661 3.15 1679 3.26 1696 3.37 — — — —
4800 1681 3.18 1698 3.29 — — — — — — ——————— — — —
Notes:
1. For Direct Drive Evaporator Fan Speed (rpm), reference Table 8, p. 9.
2. Data includes pressure drop due to standard filters and wet coils.
3. Refer to Table 11, p. 9 to determine additional static pressure drop due to other options/accessories.
4. Direct Drive Fan Motor Heat (MBH) = 2.8623xFan BHP -0.1504
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.

Evaporator Fan Performance
RT-SVF28F-EN 7
Table 4. Direct drive evaporator fan performance - 10 tons standard efficiency with gas heat -YSC120F3,4,W*L,M low
& medium heat downflow airflow
External Static Pressure (Inches of Water)
.10 .20 .30 .40 .50 .60 .70 .80 .90 1.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
3200 1055 0.73 1081 0.81 1105 0.88 1128 0.94 1152 1.01 1177 1.09 1202 1.17 1225 1.25 1249 1.33 1273 1.42
3600 1181 1.02 1204 1.10 1226 1.19 1248 1.27 1268 1.34 1289 1.42 1311 1.50 1333 1.59 1355 1.68 1376 1.77
4000 1307 1.38 1328 1.47 1348 1.56 1368 1.65 1388 1.74 1406 1.82 1425 1.91 1444 2.00 1464 2.10 1483 2.20
4400 1433 1.82 1453 1.92 1472 2.02 1490 2.12 1508 2.22 1525 2.32 1542 2.40 1559 2.49 1577 2.59 1594 2.69
4800 1560 2.34 1578 2.45 1595 2.56 1613 2.67 1629 2.77 1646 2.89 1662 2.99 1677 3.09 1692 3.18 — —
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
3200 1296 1.51 1319 1.61 1343 1.70 1366 1.81 1390 1.91 1415 2.02 1438 2.11 1461 2.21 1484 2.31 1506 2.41
3600 1397 1.86 1418 1.95 1439 2.05 1460 2.16 1480 2.27 1501 2.38 1522 2.49 1543 2.61 1564 2.72 1585 2.83
4000 1503 2.30 1522 2.39 1542 2.49 1561 2.60 1579 2.70 1598 2.81 1616 2.93 1635 3.05 1654 3.17 1673 3.29
4400 1612 2.80 1630 2.91 1647 3.02 1665 3.13 1683 3.24 1700 3.34 — — — — — — — —
4800 - - — — — — — — — — — — — — — — — — — —
Notes:
1. For Direct Drive Evaporator Fan Speed (rpm), reference Table 8, p. 9.
2. Data includes pressure drop due to standard filters and wet coils.
3. Refer to Table 11, p. 9 to determine additional static pressure drop due to other options/accessories.
4. Direct Drive Fan Motor Heat (MBH) = 2.8623xFan BHP -0.1504
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.
Table 5. Direct drive evaporator fan performance - 10 tons standard efficiency with gas heat -YSC120F3,4,W*L,M low
& medium heat horizontal airflow
External Static Pressure (Inches of Water)
.10 .20 .30 .40 .50 .60 .70 .80 .90 1.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
3200 1043 0.70 1072 0.78 1099 0.85 1128 0.94 1154 1.02 1179 1.10 1203 1.17 1227 1.26 1250 1.35 1274 1.44
3600 1166 0.98 1192 1.06 1217 1.14 1241 1.23 1267 1.33 1291 1.42 1314 1.51 1335 1.59 1356 1.68 1378 1.78
4000 1290 1.32 1314 1.41 1337 1.50 1359 1.60 1381 1.69 1404 1.80 1426 1.91 1447 2.01 1467 2.10 1486 2.20
4400 1415 1.73 1436 1.83 1458 1.94 1478 2.04 1498 2.14 1518 2.25 1539 2.37 1560 2.49 1579 2.60 1597 2.70
4800 1540 2.23 1560 2.34 1579 2.45 1598 2.56 1617 2.67 1635 2.79 1653 2.90 1672 3.03 1692 3.16 — —
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
3200 1298 1.53 1323 1.63 1347 1.72 1370 1.82 1394 1.92 1416 2.02 1437 2.12 1459 2.22 1482 2.33 1503 2.43
3600 1398 1.88 1419 1.98 1440 2.08 1462 2.19 1484 2.30 1505 2.40 1527 2.52 1547 2.62 1568 2.74 1587 2.84
4000 1505 2.30 1524 2.41 1542 2.51 1562 2.63 1581 2.74 1600 2.85 1619 2.97 1639 3.09 1658 3.20 1677 3.32
4400 1615 2.81 1633 2.91 1650 3.02 1667 3.14 1685 3.26 1700 3.38 — — — — — — — —
4800 — — — — — — — — — — — — — — — — — — — —
Notes:
1. For Direct Drive Evaporator Fan Speed (rpm), reference Table 8, p. 9.
2. Data includes pressure drop due to standard filters and wet coils.
3. Refer to Table 11, p. 9 to determine additional static pressure drop due to other options/accessories.
4. Direct Drive Fan Motor Heat (MBH) = 2.8623xFan BHP -0.1504
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.

Evaporator Fan Performance
8 RT-SVF28F-EN
Table 6. Direct drive evaporator fan performance - 10 tons with standard efficiency gas heat -YSC120F3,4,W*H high
heat downflow airflow
External Static Pressure (Inches of Water)
.10 .20 .30 .40 .50 .60 .70 .80 .90 1.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
3200 1055 0.70 1082 0.79 1109 0.87 1132 0.93 1156 1.01 1180 1.09 1205 1.17 1228 1.25 1252 1.33 1275 1.41
3600 1180 0.98 1205 1.07 1229 1.16 1252 1.25 1272 1.33 1293 1.40 1315 1.49 1337 1.59 1358 1.68 1379 1.77
4000 1305 1.32 1328 1.42 1350 1.52 1372 1.63 1392 1.73 1410 1.80 1429 1.89 1448 1.99 1468 2.09 1488 2.19
4400 1432 1.73 1452 1.84 1473 1.96 1493 2.07 1512 2.19 1530 2.29 1547 2.38 1564 2.47 1581 2.57 1599 2.68
4800 1558 2.22 1577 2.34 1596 2.47 1615 2.59 1633 2.72 1650 2.84 1667 2.96 1683 3.06 1698 3.15 — —
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
3200 1298 1.49 1322 1.59 1348 1.69 1374 1.81 1398 1.91 1421 2.00 1443 2.10 1465 2.20 1488 2.30 1511 2.41
3600 1400 1.86 1421 1.95 1441 2.04 1462 2.14 1483 2.24 1507 2.36 1530 2.48 1552 2.61 1574 2.72 1594 2.83
4000 1507 2.29 1526 2.39 1544 2.49 1563 2.59 1582 2.69 1601 2.79 1619 2.90 1639 3.01 1657 3.13 1678 3.26
4400 1617 2.79 1635 2.91 1652 3.02 1669 3.13 1687 3.23 — — — — — — — — — —
4800 — — — — — — — — — — — — — — — — — — — —
Notes:
1. For Direct Drive Evaporator Fan Speed (rpm), reference Table 8, p. 9.
2. Data includes pressure drop due to standard filters and wet coils.
3. Refer to Table 11, p. 9 to determine additional static pressure drop due to other options/accessories.
4. Direct Drive Fan Motor Heat (MBH) = 2.8623xFan BHP -0.1504
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.
Table 7. Direct drive evaporator fan performance - 10 tons standard efficiency with gas heat -YSC120F3,4,W*H high
heat horizontal airflow
External Static Pressure (Inches of Water)
.10 .20 .30 .40 .50 .60 .70 .80 .90 1.00
cfm rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp rpm bhp
3200 1054 0.72 1084 0.79 1112 0.86 1141 0.95 1168 1.04 1193 1.12 1218 1.20 1242 1.28 1266 1.38 1289 1.48
3600 1179 1.00 1205 1.08 1231 1.16 1256 1.24 1282 1.35 1306 1.45 1329 1.54 1352 1.63 1374 1.72 1395 1.82
4000 1304 1.35 1328 1.44 1352 1.53 1375 1.62 1397 1.71 1420 1.83 1442 1.94 1463 2.04 1484 2.14 1504 2.24
4400 1429 1.78 1452 1.88 1474 1.98 1495 2.07 1515 2.17 1536 2.27 1556 2.40 1577 2.53 1597 2.64 1616 2.75
4800 1555 2.29 1576 2.40 1596 2.51 1616 2.61 1635 2.72 1654 2.82 1673 2.93 1692 3.07 — — — —
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
3200 1314 1.57 1338 1.65 1362 1.74 1385 1.84 1407 1.93 1430 2.02 1453 2.12 1477 2.22 1498 2.32 1521 2.44
3600 1416 1.92 1436 2.03 1458 2.14 1480 2.24 1501 2.33 1522 2.43 1543 2.54 1563 2.64 1583 2.74 1604 2.85
4000 1524 2.35 1543 2.46 1562 2.56 1581 2.68 1600 2.80 1619 2.93 1638 3.04 1658 3.15 1677 3.26 1695 3.37
4400 1635 2.87 1653 2.97 1671 3.09 1689 3.21 — — ——————— — — —
4800 — — — — — — — — — — ——————— — — —
Notes:
1. For Direct Drive Evaporator Fan Speed (rpm), reference Table 8, p. 9.
2. Data includes pressure drop due to standard filters and wet coils.
3. Refer to Table 11, p. 9 to determine additional static pressure drop due to other options/accessories.
4. Direct Drive Fan Motor Heat (MBH) = 2.8623xFan BHP -0.1504
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.

RT-SVF28F-EN 9
Performance Data
Table 8. RPM table
T/YSC120F
Potentiometer
Voltage Motor RPM Potentiometer Voltage Motor RPM
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 5V
Table 9. 10 tons air temperature rise across electric
heaters (°F)
kW Stages
10 Tons
4000 cfm(a)
TSC120F3,4,W
(a)Minimum allowable airflow with a 54 kW heater is
3400 CFM
18.0 1 14.2
27.0 2 21.3
36.0 2 28.5
54.0 2 42.7
Notes:
1. For minimum design airflow, see airflow
performance table for each unit.
2. To calculate temp rise at different airflow, use the
following formula:
Temp. rise across Electric Heater = kWx3414/
1.08xCFM.
Table 10. 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
10 T/YSC120F 91 86 90 86 82 78 73 67 88
Note: Tests follow AHRI270-95.
Table 11. Static pressure drop through accessories (inches water column) - 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
10 T/YSC120F 3200 0.07 0.10 0.14 0.17 0.05 0.42 0.18 0.14 0.05 — 0.02 0.03 0.05
10 T/YSC120F 4000 0.11 0.15 0.16 0.26 0.07 0.63 0.21 0.30 0.08 — 0.02 0.03 0.05
10 T/YSC120F 4800 0.16 0.20 0.18 0.34 0.09 0.91 0.34 0.35 0.10 — 0.03 0.04 0.06
(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.

10 RT-SVF28F-EN
Electrical Data
Table 12. Unit wiring - standard efficiency
Standard Indoor Fan Motor(a)
Tons Unit Model Number Voltage Range MCA
Max Fuse Size
or Max Circuit
Breaker
10 T/YSC120F3 187-253 49.6 60
10 T/YSC120F4 414-506 22.7 30
10 T/YSC120FW 517-633 18.9 25
(a) The standard motor for the 3-phase models is a Belt Drive Motor.
Table 13. Unit wiring with electric heat (single point connection) - standard efficiency
Standard Indoor Motor
Tons Unit Model Number Heater Model Number Heater kW Rating(a) Control
Stages MCA
Max Fuse Size or
Max Circuit
Breaker
208/230 Volts Three Phase
10 TSC120F3 BAYHTRA318* 13.5/18.0 1 57.5/64.8 60/70
10 TSC120F3 BAYHTRA327* 20.3/27.0 2 81.0/91.9 90/100
10 TSC120F3 BAYHTRA336* 27.0/36.0 2 104.5/118.9 110/125
10 TSC120F3 BAYHTRA354* 40.6/54.0 2 151.4/140.5 175/150
480 Volts Three Phase
10 TSC120F4 BAYHTRA418* 18.0 1 32.5 35
10 TSC120F4 BAYHTRA427* 27.0 2 46.0 50
10 TSC120F4 BAYHTRA436* 36.0 2 59.5 60
10 TSC120F4 BAYHTRA454* 54.0 2 70.4 80
575 Volts Three Phase
10 TSC120FW BAYHTRAW18* 18.0 1 27.0 30
10 TSC120FW BAYHTRAW36* 36.0 2 48.6 50
10 TSC120FW BAYHTRAW54* 54.0 2 57.4 60
(a) Heater kwratings are at 208/240V for 208/230V units, 480V for 460V units and 600V for 575V units.
Table 14. 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
10 T/YSC120F3 2 208-230 3 4.9/3.8 3500/3500 19.6/13.1 136.0/83.0 1 208-230 1 0.75 3.5 9.3
10 T/YSC120F4 2 460 3 4.9/3.8 3500/3500 8.2/6.1 66.0/41.0 1 460 1 0.75 2.0 6.2
10 T/YSC120FW 2 575 3 4.9/3.8 3500/3500 6.7/4.4 54.0/33.0 1 575 1 0.75 1.8 5.4
(a)Amp draw for each motor; multiply value by number of motors to determine total amps.
(b)hp for each compressor.

Electrical Data
RT-SVF28F-EN 11
Table 15. Electrical characteristics - standard evaporator fan motor - 60 cycle - direct or belt drive standard efficiency
Unit Model Direct or Belt Amps
Tons Number Drive No. Volts Phase hp FLA LRA
10 T/YSC120F3 Direct Drive 1 208-230 3 3.80 8.50-8.50 —
10 T/YSC120F4 Direct Drive 1 460 3 3.60 4.30 —
10 T/YSC120FW(a) Direct Drive 1 460 3 3.60 4.30 —
(a)T/YSC120FW utilize 460V Evaporator Motors.
Table 16. Electrical characteristics — power exhaust (cooling and gas/electric)
Tons Volts Phase hp rpm FLA LRA
10 208-230 1 0.87 1075(a) 5.7 16.3
10 460 1 0.87 1075(a) 3.3 6.8
10 575 1 0.87 1075(a) 2.3 5.4
(a)Two speed.
Table 17. Electrical characteristics - inducer motor
Unit Model Number Stages hp rpm Volts Phase LRA
YSC120F 2 1/15 3350 208-230 1 0.4

12 RT-SVF28F-EN
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. 16.
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
system is connected to a remote panel, the “SERVICE”
LED will be turned on when this failure occurs.
1High efficiency units only.

Sequence of Operation
RT-SVF28F-EN 13
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.

Sequence of Operation
14 RT-SVF28F-EN
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 18, p. 14 lists the selectable dry bulb values by
potentiometer setting.
2. Reference Enthalpy - controlling the economizer cycle
by sensing the outdoor air humidity. Table 18, p. 14
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 18. 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)

Sequence of Operation
RT-SVF28F-EN 15
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.
VAV Units Only-Sequence of
Operation
Supply Air Pressure Control
ReliaTel Option Module Control (RTOM)
Supply fan is driven by a pulse-width modulation (PWM)
signal from the RTOM. A pressure transducer measures
duct static pressure, and the supply fan is modulated to
maintain the supply air static pressure within an
adjustable user-defined range.The range is determined by
the supply air pressure setpoint and supply air pressure
deadband, which are set through a unit mounted
potentiometer.The RTOM provides supply fan motor
speed modulation.
The supply fan will accelerate or decelerate as required to
maintain the supply static pressure setpoint.
Supply Air Static Pressure Limit
The control of the supply fan and VAV boxes are
coordinated, with respect to time, during unit start up and
transition to/from Occupied/Unoccupied modes to
prevent overpressurization of the supply air ductwork.
However, if for any reason the supply air pressure exceeds
the fixed supply air static pressure limit of 3.5" W.C., the
supply fan is shut down and theVAV boxes are closed.The
unit is then allowed to restart three times. If the
overpressurization condition occurs on the fourth time,
the unit is shut down and a manual reset diagnostic is set
and displayed at any of the remote panels with LED status
lights or communicated to the Integrated Comfort system.
Supply Air Temperature Controls
Cooling/Economizer
During occupied cooling mode of operation, the
economizer (if available) and primary cooling are used to
control the supply air temperature.The supply air
temperature setpoint is user-defined at the unit mounted
VAV Setpoint Potentiometer or at the remote panel. If the
enthalpy of the outside air is appropriate to use "free
Table 19. 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.

Sequence of Operation
16 RT-SVF28F-EN
cooling," the economizer will be used first to attempt to
satisfy the supply setpoint. On units with economizer, a
call for cooling will modulate the fresh air dampers open.
The rate of economizer modulation is based on deviation
of the discharge temperature from setpoint, i.e., the further
away from setpoint, the faster the fresh air damper will
open. Note that the economizer is only allowed to function
freely if ambient conditions are below the enthalpy control
setting or below the return air enthalpy if unit has
comparative enthalpy installed. If outside air is not
suitable for "economizing," the fresh air dampers drive to
the minimum open position. A field adjustable
potentiometer on the Economizer Actuator, or a remote
potentiometer can provide the input to establish the
minimum damper position. At outdoor air conditions
above the enthalpy control setting, primary cooling only is
used and the fresh air dampers remain at minimum
position. If the unit does not include an economizer,
primary cooling only is used to satisfy cooling
requirements.
Supply Air Setpoint Reset
Supply air reset can be used to adjust the supply air
temperature setpoint on the basis of a zone temperature,
return air temperature, or on outdoor air temperature.
Supply air reset adjustment is available on the unit
mounted VAV Setpoint Potentiometer for supply air
cooling control.
Reset Based on Outdoor AirTemperature. Outdoor
air cooling reset is sometimes used in applications where
the outdoor temperature has a large effect on building
load. When the outside air temperature is low and the
building cooling load is low, the supply air setpoint can be
raised, thereby preventing subcooling of critical zones.
This reset can lower usage of primary cooling and result in
a reduction in primary cooling energy usageThere are two
user-defined parameters that are adjustable through the
VAV Setpoint Potentiometer: reset temperature setpoint
and reset amount.The amount of reset applied is
dependent upon how far the outdoor air temperature is
below the supply air reset setpoint.The amount is zero
where they are equal and increases linearly toward the
value set at the reset amount input.The maximum value
is 20°F. If the outdoor air temperature is more than 20°F
below the reset temperature setpoint the amount of reset
is equal to the reset amount setpoint.
Reset Based on Zone or Return Temperature. Zone
or return reset is applied to the zone(s) in a building that
tend to overcool or overheat.The supply air temperature
setpoint is adjusted based on the temperature of the
critical zone(s) or the return air temperature.This can have
the effect of improving comfort and/or lowering energy
usage.The user-defined parameters are the same as for
outdoor air reset. Logic for zone or return reset control is
the same except that the origins of the temperature inputs
are the zone sensor or return sensor respectively.The
amount of reset applied is dependent upon how far the
zone or return air temperature is below the supply air reset
setpoint.The amount is zero where they are equal and
increases linearly toward the value set at the reset amount
potentiometer on the VAV Setpoint Potentiometer.The
maximum value is 3°F. If the return or zone temperature is
more than 3°F below the reset temperature setpoint the
amount of reset is equal to the reset amount setpoint.
Zone Temperature Control
Unoccupied Zone Cooling
During Unoccupied mode, the unit is operated as a CV
unit. VAV boxes are driven full open and the supply fan is
commanded to full speed.The unit controls zone
temperature to the Unoccupied zone cooling setpoints.
Daytime Warm-up
During occupied mode, if the zone temperature falls to a
temperature three degrees below the Morning Warm-up
setpoint, Daytime Warm-up is initiated.The system
changes to CV heating (full unit airflow), theVAV boxes are
fully opened and the CV heating algorithm is in control
until the MorningWarm-up setpoint is reached.The unit is
then returned to VAV cooling mode.The Morning Warm-
up setpoint is set at the unit mounted VAV Setpoint
potentiometer or at a remote panel.
Morning Warm-up (MWU)
Morning warm-up control (MWU) is activated whenever
the unit switches from unoccupied to occupied and the
zone temperature is at least 1.5°F below the MWU setpoint.
When MWU is activated the VAV box output will be
energized for at least 6 minutes to drive all boxes open, the
supply fan is commanded to full speed, and full heat (gas
or electric) is energized. When MWU is activated the
economizer damper is driven fully closed. When the zone
temperature meets or exceeds the MWU setpoint minus
1.5°F, the heat will be turned or staged down. When the
zone temperature meets or exceeds the MWU setpoint
then MWU will be terminated and the unit will switch over
to VAV cooling.
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

Sequence of Operation
RT-SVF28F-EN 17
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.
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 18,
p. 14 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)

Sequence of Operation
18 RT-SVF28F-EN
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.
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 20. 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).

RT-SVF28F-EN 19
Pressure Curves
Figure 1. T/YSC120F pressure curve system 1
150
200
250
300
350
400
450
500
550
600
650
700
750
100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200
DischargePressure,PSIG
SuctionPressure,PSIG
55F OD Ambient
65F OD Ambient
75F OD Ambient
85F OD Ambient
95F OD Ambient
105F OD Ambient
115F OD Ambient
68/57F ID DB/WB
74/62F ID DB/WB
80/67F ID DB/WB
86/72F ID DB/WB
Figure 2. T/YSC120F pressure curve system 2
150
200
250
300
350
400
450
500
550
600
650
700
750
100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200
DischargePressure,PSIG
SuctionPressure,PSIG
68/57F ID DB/WB
74/62F ID DB/WB
55F OD Ambient
65F OD Ambient
80/67F ID DB/WB
86/72F ID DB/WB
75F OD Ambient
85F OD Ambient
95F OD Ambient
105F OD Ambient
115F OD Ambient

20 RT-SVF28F-EN
Subcooling Charging Chart
Figure 3. T/YSC120F subcooling charging chart - PSIG
SYS 1
SYS 2