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Honeywell T874 Product Data

Multistage thermostats and subbases
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Table of Contents

APPLICATION

These thermostats and subbases provide low voltage control
of multistage heating and cooling systems, including heat
pump systems.
® U.S. Registered Trademark
Copyright © 2001 Honeywell • All Rights Reserved
T874 Multistage Thermostats
and Q674 Subbases

FEATURES

• T874 Thermostat has silent, dust-free mercury
switches operated by coiled bimetal elements.
• Heat anticipator(s) are adjustable or fixed cooling
anticipator(s) are fixed.
• Individual heat and cool levers and scales (most
models) for temperature setting located on top of
thermostat case.
• Cover thermometer on most T874 Multistage
Thermostat models.
• Locking cover and locking lever screws available for
T874 Multistage Thermostats.
• Versaguard™ Thermostat Guard or custom key lock
thermostat guards available for T874 Multistage
Thermostats.
• T874 Thermostat requires a Q674 Subbase.
• Q674 Subbase provides system and fan switching,
wiring terminals and mounting base for T874
Multistage Thermostat.
• Adapter plate available for mounting Q674 on wall or
horizontal outlet box.
• Light-emitting diodes (LEDs) located on subbase for
easy reference.
• Up to three stages each of heating and cooling control
possible.
• Models with setpoint restrictions and locking cover
with no thermometer available for Department of
Defense (DoD) and other special applications.
• Outdoor reset used on some models to improve
thermal performance.
Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Checkout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Understanding Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Cross Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Wiring Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
PRODUCT DATA
Contents
60- 2485- 8

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  Summary of Contents for Honeywell T874

  • Page 1 These thermostats and subbases provide low voltage control of multistage heating and cooling systems, including heat pump systems. ® U.S. Registered Trademark Copyright © 2001 Honeywell • All Rights Reserved T874 Multistage Thermostats and Q674 Subbases FEATURES • T874 Thermostat has silent, dust-free mercury switches operated by coiled bimetal elements.
  • Page 2: Application

    Honeywell, 1885 Douglas Drive North Minneapolis, Minnesota 55422-4386 (800) 328-5111 In Canada—Honeywell Limited/Honeywell Limitée, 35 Dynamic Drive, Scarborough, Ontario M1V 4Z9. International Sales and Service Offices in all principal cities of the world. Manufacturing in Australia, Canada, Finland, France, Germany, Japan, Mexico, Netherlands, Spain, Taiwan, United Kingdom, U.S.A.
  • Page 3: Specifications

    50 60 70 80 AUTO OFF EM. HT. HEAT AUTO COOL Fig. 1. T874 Thermostat and Q674 Subbase dimensions in in. (mm). Optional Specifications (T874 Only): Temperature scale ranges are 40° to 75°F (4° to 24°C) heat- ing and 75° to 90°F (24° to 32°C) cooling with stop; 44° to 68°F (7°...
  • Page 4 Changeover stage operates with heating. Fixed voltage type anticipation. Changeover stage operates with heating; a secondary changeover is provided in cooling switch. Provides night setback used with standard T874 and timer-operated remote switching. Manual changeover stage—use Q674B,L subbase. Changeover stage operates with cooling.
  • Page 5 Changeover stage operates with heating. Fixed voltage type anticipation. Changeover stage operates with heating; a secondary changeover is provided in cooling switch. Provides night setback used with standard T874 and timer-operated remote switching. Manual changeover stage—use Q674B,L subbase. Changeover stage operates with cooling.
  • Page 6 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Q674E—Standard and TRADELINE. Q674F—Two LED models. — EM.HT. light. — Provision for AUTO fan operation in EM.HT. Q674G—O and B terminals. Q674J—Provision for AUTO fan operation in EM.HT. — Provision for outdoor thermistor. Q674K—Standard.
  • Page 7 It is not a calibration problem. Location Install the thermostat about 5 ft (1.5m) above the floor in an area with good air circulation at average temperature. Do not mount the thermostat where it can be affected by: —...
  • Page 8: Wire Subbase

    T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES WIRES THROUGH WALL OPENING WALL ANCHORS M926 SUBBASE Fig. 5. Installing Q674 Subbase on wall. WIRING TERMINAL SPIRIT LEVEL POST FOR MOUNTING MOUNTING HOLES (4) THERMOSTAT (2) Fig. 6. Subbase components and leveling procedure.
  • Page 9: Terminal Designations

    W3 controls the auxiliary heat like W2, and allows adding additional stages of auxiliary heat with outdoor thermostats while maintaining the proper second stage anticipation. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES JUMPER WIRE (SUPPLIED WITH SOME MODELS) 1 TWO ADJACENT TERMINALS SHOWN JUMPERED ARE FOR EXAMPLE ONLY.
  • Page 10 1. Remove the thermostat cover by pulling the bottom edge of the cover upward until it snaps free of the mounting slots. 2. Turn to the back of the T874 Thermostat. Locate the hole for the brass insert in the plastic base below the LED window.
  • Page 11: Mount Thermostat

    Set the Heat Anticipator Move the indicator to match the primary control current draw. When using a T874 Thermostat with two stages of heating, set each heat anticipator to match its respective primary control current draw. If you cannot find the current rating on...
  • Page 12: Settings

    T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Most heat pump systems should cycle 2-1/2 to 3 times per hour. 4. Hang the upper edge of the thermostat cover on top of the thermostat base and swing the cover downward until it engages with the cover clip.
  • Page 13: Checkout

    Heating Move the system switch on the Q674 Subbase to HEAT or AUTO. Move the heat lever on the T874 about 10°F (6°C) above room temperature. See Fig. 12. Heating system should start and the fan should run after a short delay. Move the heat lever about 10°F (6°C) below room temperature.
  • Page 14: Calibration

    T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Move the system switch on the Q674 Subbase to COOL or AUTO. Move the cool setting lever on the T874 Multistage Thermostat about 10°F (6°C) below room temperature. See Fig. 12. The cooling equipment and fan should start. If the system has two stages of cooling, both stages should start.
  • Page 15 Each anticipator is identified and each switch affected is named (EX: H1 anticipator, C1 anticipator). All T874 Multistage Thermostats use mercury switches. Each schematic indicates switch operation by being drawn in the open position with an arrow indicating operation with a temperature RISE or FALL.
  • Page 16 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. AUXILIARY HEAT LED AVAILABLE ON SOME MODELS. Fig. 17. Internal schematic and typical hookup of a T874R Thermostat and Q674L Subbase in a heat pump application. The thermostat provides two-stage heating and one-stage cooling manual changeover operates on cooling.
  • Page 17 EM. HT. HEAT POWER SUPPLY. PROVIDE COOL DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 19. Tracing the heat 1 and anticipation circuit. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH AUX. HT. (GREEN) EM. HT. LED (RED) HEAT SUBBASE AUX.
  • Page 18 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1/ C1 ANTICIPATOR FALL ANTICIPATOR FALL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. THERMOSTAT H1/C1 ANTICIPATOR FALL ANTICIPATOR FALL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 21. Tracing the heat 2, anticipation and AUX. HT. LED circuit.
  • Page 19 ANTICIPATOR FALL SYSTEM SWITCH EM. HT. HEAT POWER SUPPLY. PROVIDE DISCONNECT MEANS AND COOL OVERLOAD PROTECTION AS REQUIRED. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE AUX. HT. (GREEN) EM. HT. LED (RED) SUBBASE AUX. HT. (GREEN) EM. HT. LED (RED) Fig.
  • Page 20 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1/C1 ANTICIPATOR FALL ANTICIPATOR FALL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. THERMOSTAT H1/C1 ANTICIPATOR FALL ANTICIPATOR FALL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. 60-2485—8 SUBBASE...
  • Page 21 Mechanical differential is the difference between the make and break points of each switch. The mechanical differential for the T874 is 1°F (0.6°C) between the stages of heating or M5823 between the stages of cooling for most models.
  • Page 22: Operation

    Turn thermostat upside-down, and the blank insert falls out. 60-2485—8 A strip of four inserts is included with TRADELINE T874. Drop a strip into the recessed area behind the scaleplate so selected LEDs show. Make sure insert is completely seated in recessed area.
  • Page 23 OFF EM. HT. HEAT COOL Fig. 32. System switching for manual changeover. Commercial Rooftop Application The T874 can be used as part of a commercial rooftop application to run mechanical cooling. An economizer is often used as part of a rooftop application to save on air conditioning.
  • Page 24 A heat pump, being a mechanical refrigeration system, should be cycled at a rate of 2-1/2 to 3 times an hour. With a T874, this is accomplished by setting the anticipator at the total current draw of the controlled device (the contactor and possibly the changeover relay or valve).
  • Page 25 It comes on with the compressor high speed if an outdoor thermostat—wired in series with it— is made. See Fig. 35. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT HEAT 2 HEAT 1...
  • Page 26: Auxiliary Heat

    T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Defrost Control In some regions, during half or more of the heating season, the outdoor coil operates below 32°F (0°C) Frost or ice builds up on the outdoor coil of a heat pump similarly to the frost buildup in a household refrigerator.
  • Page 27: Emergency Heat

    The same is true with 50,000 or 60,000 Btu (146.5 or 178.8 kW) of heat pump auxiliary electric heat. The T874 can provide the same high quality control. This scheme also eliminates the need for outdoor thermostats and thus offers the manufacturer an opportunity to reduce unit cost.
  • Page 28 Here is how it works: HEAT RELAY 2 • On a call for cooling, the thermostat makes R to Y, the contactor coil is powered, and the compressor motor turns on. • At the same time, the indicator light is energized.
  • Page 29: Cross Reference

    CROSS REFERENCE The following section lists the current T874 Trade replace- ments for T872 and T874 Multistage Thermostats. It also lists the Q674 Trade replacements for Q672 and Q674 Subbases. All thermostats listed carry the Honeywell logo unless otherwise noted.
  • Page 30: Cross Reference

    Fast cycle performance on both heat stages; anticipator range 0.12-0.6A C1095 Payne logo; no. 0.1-0.175 When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase. 60-2485—8 Table 6. T872-T874 Thermostat Cross Reference. Description T874A1010...
  • Page 31 C1491 Lennox logo; no. 64A0501; locking cover; no thermometer; meets DoD specs When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 6. T872-T874 Thermostat Cross Reference.
  • Page 32 ITT logo D1128 Carrier logo D1136 No anticipator on stage 1 cool; used with Q672C1029 When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase. 60-2485—8 Table 6. T872-T874 Thermostat Cross Reference. Description Y594R1425 Y594R1425...
  • Page 33 E1002 Standard OEM E1010 TRADELINE E1028 Westinghouse logo When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 6. T872-T874 Thermostat Cross Reference. Description T874D1165 T874D1165 T874D1165/...
  • Page 34 Adjustable anticipator stage 2 heat; fixed anticipator stage 1 heat and cool; changeover with cooling; used with Q672E1027. When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase. 60-2485—8 Table 6. T872-T874 Thermostat Cross Reference.
  • Page 35 Tappan; no. B13708-57; used with Q672L1078 for 8 and 10 ton heat pumps with 2 compressors. When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 6. T872-T874 Thermostat Cross Reference.
  • Page 36 T872N Heat pump model; 2-stage heat, 1-stage cool plus changeover, changeover in heat mode. N1002 When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase. 60-2485—8 Table 6. T872-T874 Thermostat Cross Reference. Description Y594G1393...
  • Page 37 L1136. R1115 Friedrich logo; fixed anticipator; used with Q672B1244, L1086. When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 6. T872-T874 Thermostat Cross Reference. Description T874N1016/...
  • Page 38 Westinghouse logo; used with Q672L1268 and C815A1021. W1035 TRADELINE; used with C815A1043 and Q672B1251. When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase. 60-2485—8 Table 6. T872-T874 Thermostat Cross Reference. Description Y594R1664 None...
  • Page 39 Friedrich; heat mode changeover; used with T872R1115. B1251 Used with T872W1035 and C815A1043. When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and subbase. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 7. Q672-Q674 Subbase Cross Reference. Q674 Trade...
  • Page 40 Heat pump circuit; W1-Y2 jumper; cool mode changeover. E1043 Heat pump circuit; heat mode changeover. When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and subbase. 60-2485—8 Table 7. Q672-Q674 Subbase Cross Reference. Q674 Trade Description...
  • Page 41 LED; cool mode changeover; compressor lockout and auto fan in EM. HT.; used with T872G1109, G1216, G1372. When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and subbase. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 7. Q672-Q674 Subbase Cross Reference.
  • Page 42 Singer no. 02005649; French wording; O-B jumper. G1066 SLI-Mammoth; heat pump; heat mode changeover. When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and subbase. 60-2485—8 Table 7. Q672-Q674 Subbase Cross Reference. Q674 Trade Description Replacement...
  • Page 43 EM. HT.; auto fan in EM. HT; used with T872R1065, R1081, R1107. When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and subbase. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 7. Q672-Q674 Subbase Cross Reference.
  • Page 44 York special; used with T872R1222. L1300 Amana special; no. C62345-1; used with T872R1230. L1326 Singer; used with T872R1255. When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and subbase. 60-2485—8 Table 7. Q672-Q674 Subbase Cross Reference. Q674 Trade Description Replacement...
  • Page 45 System: EM. HT.-HEAT-COOL. P1009 Carrier special; no. HH93AZ069; used with T872G1075 (HH07AT071). When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and subbase. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 7. Q672-Q674 Subbase Cross Reference. Q674 Trade...
  • Page 46 Number T874A 1-stage heat, 1-stage cool. A1002 44, 65 Honeywell logo; Standard OEM; used with Q674B1331. A1010 Honeywell logo; includes Allen wrench and screws to lock cover; non-adjustable range stops set at 72°F (max. heat) and 78°F (min. cool) (22-26°C); field adjustable locking levers.
  • Page 47 A1465 Honeywell Trol-A-Temp™ logo; Premier White® color; heat anticipator factory set at 0.10A; used with Q674E1379. Both the thermostat and subbase must be replaced. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 8. T874 Cross Reference. Description Trade Model Replacement Remarks...
  • Page 48 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number A1481 Obsolete. Honeywell logo; Carrier part no. HH621602; includes locking cover and non-adjustable range stops set at 72°F (max. heat) and 78°F (min. cool). A1507 Obsolete. Climate-Tel logo; includes Allen wrench and screws to lock cover and non-adjustable range stops set at 72°F (max.
  • Page 49 Obsolete. Carrier Synergy 2000 logo; part no. HH07AT199; °C scaleplate; used with Q674E1395 (HH93AZ209). T874C 2-stage heat, 1-stage cool. C1000 44, 76 Honeywell logo; used with Q674B1075, C1181; used in Y594C1058. C1018 60, 61, Honeywell logo; TRADELINE model; includes Allen 81, 92 wrench and screws to lock cover;...
  • Page 50 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number C1216 Obsolete. Fasco part no. 1230-8197. C1224 Obsolete. Square D logo. C1240 Honeywell logo; Honeywell Canada TRADELINE model; °C scaleplate; includes Allen wrench and screws to lock cover. C1257 Obsolete. Singer part no. 0200-5931; 8°F (4.4°C) differential between H1 and H2 heat.
  • Page 51 Obsolete. Honeywell logo; meets DoD specifications; used with Q674L1157. C1513 Obsolete. Borg-Warner multi-logo; part no. 6TH11703124A. C1562 Obsolete. Honeywell logo; Heil Quaker part no. HQ712001HW. C1570 Obsolete. Williamson logo; used with Q674B1000; used in Y594C1280. C1638 Obsolete. Honeywell logo; meets DoD specifications;...
  • Page 52 Q674B1554; used in Y594C1421. T874D 2-stage heat, 2-stage cool. D1009 166, 82 Obsolete. Honeywell logo; used with Q674F1337, E1007; used in Y594D1222, D1339. D1017 44, 88 Obsolete. Honeywell logo; TRADELINE model; includes Allen wrench and screws to lock cover; used with Q674A-G and Q674E1155.
  • Page 53 51, 53 Obsolete. Carrier logo. D1462 Obsolete. Fedders multi-logo; part no. THTX-220-A0HB, 88-58-00550-001; used with Q674E1205. Both the thermostat and subbase must be replaced. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 8. T874 Cross Reference. Description Trade Model Replacement Remarks T874D1165 Replacement has °F...
  • Page 54 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number D1470 Obsolete. York logo; part no. 2TH04701624A; includes Allen wrench and screws to lock cover; °C scaleplate. D1488 Obsolete. Risco special. D1496 Obsolete. Borg Warner multi-logo; part no. 6TH04701524A; includes Allen wrench and screws to lock cover.
  • Page 55 Model Fig. Number D1801 45, 208 Trol-A-Temp by Honeywell logo; H1 and H2 anticipators set at 0.10A; used with Q674B1463, D1115. D1819 Marv Air Com Stat logo; part no. 50059; adjustable interstage between H1 and H2 and between C1 and C2;...
  • Page 56 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number D2056 Obsolete. ComStat logo; part no. 50056; °F/°C scaleplate; adjustable interstage on both heating and cooling; includes locking cover and field-adjustable locking levers. D2064 Obsolete. Carrier Weathermaker; part no. HH07AT209; stage 1 and 2 heat anticipator factory set 0.1A; taupe color;...
  • Page 57 Obsolete. Honeywell logo; °C scaleplate; used with 40003440-001 wallplate; used in Y594F1022. F1049 Obsolete. Lennox logo; °C scaleplate. F1056 Obsolete. Honeywell logo; stages 1 and 2 heat electrically isolated; used with Q674D1008. F1072 Obsolete. Wesco logo; heat anticipator factory set at 0.8A.
  • Page 58 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number G1014 86, 150 Obsolete. Lennox logo; part no. 24F5801; °F/°C scaleplate; H2 anticipator factory set at 0.25A for fast cycle performance; changeover in cooling mode; independent heating and cooling circuits; used with Q674E1148, F1113.
  • Page 59 Model Fig. Number G1204 Honeywell logo; designed for use on Trane heat pumps; no H2 anticipation; changeover in cooling mode; used with Q674J1043 and C815A1005; used in Y594G1161. G1212 Obsolete. Honeywell logo; H2 anticipator factory set at 0.2A; changeover in cooling mode; includes shunt to bypass H2 anticipator with W3 heat relays;...
  • Page 60 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number G1444 Obsolete. ROCA logo; °C scaleplate; used with Q674J1027. G1451 Obsolete. BDP multi-logo; part no. HH641502; used with Q674F1212; used in Y594G1245. G1469 Obsolete. No logo; Addison special; used with Q674F1345; used in Y594G1344.
  • Page 61 68°F (max. heat) and 78°F (min. cool); Premier White® color; used with Q674F1477; used in Y594G1476. G1758 Trol-A-Temp by Honeywell logo; Premier White® color; changeover is provided by Trol-A-Temp zone panel; used with Q674F1485; used in Y594G1492. G1774 Obsolete.
  • Page 62 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number G1873 Obsolete. Honeywell logo; TRADELINE model; Premier White® color; designed to replace Y594G1013 (York part no. 2TH11702424), Y594G1229 (York part no. 6TH11702424), and York part no. 2TH117704124); used with Q674J1225; used in Y594G1575.
  • Page 63 Q674C1124; used in Y594H1004. H1054 Obsolete. No logo; Friedrich part no. AT5854; used with Q674C1041. H1062 Honeywell logo; used with Q674C1249; used in Y594H1012. H1070 172, Obsolete. Carrier Heat Pump System Control logo; part no. HH07AT166; °C scaleplate; used with Q674B1406 (HH93AZ200) or Q674C1322 (HH93AZ199).
  • Page 64 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number J1069 124, Obsolete. Honeywell logo; TRADELINE model; used 144, with Q674J1282; used in Y594J1019. 206, J1077 124, Obsolete. Nordyne logo; part no. 9148300; °F/°C scaleplate. T874K Heat pump model; 2-stage heat, 1-stage cool, automatic changeover in heat.
  • Page 65 68, 97 Obsolete. Carrier Heat Pump System Control logo; part no. HH07AT205; °F/°C scaleplate; heat interstage differential 8°F (4.4°C). T874Q 1-stage heat; used with another T874 for night setback. Q1005 Honeywell logo. Q1013 Obsolete. Lennox logo; part no. 13F1201; °F/°C scaleplate.
  • Page 66 Y594R1110. R1145 Obsolete. York logo; °C scaleplate; H2 anticipator is fixed; used with Q674L1272; used in Y594R1102. R1152 Honeywell logo; used with Q674L1207, L1033; used in Y594R1243. R1160 Obsolete. Honeywell Advanced Heat Pump System logo; used with Q674L1298 and W89.
  • Page 67 Q674L1504. R1467 Honeywell logo; used with Q674L1512; used in Y594R1292. R1475 Honeywell logo; scale range 42°F to 88°F; used with Q674L1520; used in Y594R1300. R1483 Obsolete. Comfortmaker logo; °F/°C scaleplate; used with Q674L1538 and C815A1005; used in Y594R1318.
  • Page 68 R1749 Tempstar logo; part no. 1060322, TAXB004TW01; used with Q674L1132; used in Y594R1532. R1814 Obsolete. Honeywell logo; Keeprite part no. THPC; °C scaleplate; used with Q674L1132; used in Y594R1607. R1822 Honeywell logo; TRADELINE model; used with Q674L1710; used in Y594R1615.
  • Page 69 Model Fig. Number R1889 Honeywell logo; designed to replace Y594R1151 (York part no. 2TH11702324), Y594R1193 (York part no. 6TH11702224), and York part no. 2TH11704024; used with Q674L1736 and C815A1054; used in Y594R1672. R1897 Honeywell logo; Premier White® color; used with Q674L1751;...
  • Page 70 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number T874W 3-stage heat, 2-stage cool, manual changeover. W1007 Obsolete. Honeywell logo; Westinghouse special; used with Q674L1256. W1015 Honeywell logo; used with Q674B1216 and C815A1005; used in Y594W1014. W1023 Obsolete. Lennox Advanced Heat Pump System logo;...
  • Page 71 Used with T874W1015 and C815A1005; used in Y594W1014. B1224 Obsolete. Lennox part no. 25F7301; four LEDs; used with T874C1430. Both the thermostat and subbase must be replaced. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 9. Q674 Subbase Cross Reference. Description Electric Furnace: Q674 Trade Replacement...
  • Page 72 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number B1240 Obsolete. Northrup heat pump; AUX HEAT LED; used with T874G1139. B1257 Obsolete. LSI-Mammoth; RESET LED; automatic fan operation in heat and cool modes; used with T874C1471; used in Y594C1314. B1273 Obsolete.
  • Page 73 Obsolete. American Air Filter part no. 4ELN-8788; two LEDs; spring return momentary system switch position; used with T874G1485, G1535. Both the thermostat and subbase must be replaced. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 9. Q674 Subbase Cross Reference. Description Q674 Trade...
  • Page 74 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number C1207 Obsolete. Friedrich; System: OVERRIDE-AUTO-OFF; used with T874P1014. C1215 Obsolete. Friedrich part no. AQ5315; System: OVERRIDE-AUTO-OFF; OVERRIDE and SERVICE LEDs; used with T874P1022, P1030. C1223 Obsolete. Friedrich part no. AQ5323; used on systems requiring night setback contacts;...
  • Page 75 Obsolete. Borg-Warner; used with T874G. D1040 TRADELINE D1057 55, 66 Obsolete. York part no. 2TB04700424A. Both the thermostat and subbase must be replaced. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 9. Q674 Subbase Cross Reference. Description Q674 Trade Replacement Remarks...
  • Page 76 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number D1065 Obsolete. Includes two LEDs; used with T874F1122. D1099 55, 66 Obsolete. Trane part no. BAS-0430; used with T874A-F. D1107 55, 66 Obsolete. Snyder General part nos. 654958801/ 1520503/ 4ELN30070. D1115 Trol-A-Temp;...
  • Page 77 Obsolete. Carrier part no. HH93AZ181; SUPL HEAT LED; used with T874D1074 (HH07AT172). F1071 Obsolete. Square D part no. 63600-002-11; CHECK LED. Both the thermostat and subbase must be replaced. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 9. Q674 Subbase Cross Reference. Description Q674 Trade Replacement Remarks Q674E1049 E-W2 jumper required.
  • Page 78 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number F1089 Obsolete. Includes EM HEAT LED; X2-E and RC-RH jumpers. F1097 Obsolete. Southwest special; W2-X2 jumper. F1105 Obsolete. Lennox heat pump; EM HEAT LED; used with T874G1154. F1113 Obsolete. Lennox heat pump; part no. 24F6201; V-VR jumper;...
  • Page 79 F1477 TRADELINE; gray color; used with T874G1741, G1824; used in Y594G1476, G1534. F1485 Trol-A-Temp by Honeywell; changeover is provided by Trol-A-Temp zone panel; used with T874G1758; used in Y594G1492. F1501 Obsolete. Carrier two-speed compressor heat pump; used with T874S1001.
  • Page 80 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number F1675 Obsolete. WaterFurnace logo; part no. TA21H03; includes four LEDs. Q674G System: OFF-AUTO; Fan: None G1005 Obsolete. Used in Y594F1063. G1013 Obsolete. Climate Control; used with T874D1298. G1021 Obsolete. Includes O and B terminals; used with T874A-F,Q or T874D1082;...
  • Page 81 Obsolete. Carrier part no. HH93AZ172; RC-RH jumper. K1018 Obsolete. Oneida Heater part no. 3040284-02; System: OFF-WOOD-WOOD/OIL-OIL; used with T874F1106. Both the thermostat and subbase must be replaced. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 9. Q674 Subbase Cross Reference. Description Q674 Trade Replacement Remarks...
  • Page 82 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number K1026 System: OFF-WOOD-WOOD/ OIL-OIL; used with T874F1155. K1034 Obsolete. Snyder General part no. 4ELN-7920. K1042 Obsolete. Carrier part no. HH93AZ172-W; gray color; includes removable jumper between RC and RH terminals. Q674L System: EM.HT.-HEAT-OFF-COOL;...
  • Page 83 Obsolete. Lennox part no. 41F6501; V-VR jumper; used with T874D1207. L1397 Obsolete. Carrier part no. HH93AZ185A; SUPL HEAT LED. Both the thermostat and subbase must be replaced. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 9. Q674 Subbase Cross Reference. Description Q674 Trade Replacement Remarks...
  • Page 84 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number L1405 Obsolete. BDP heat pump; part no. HH641501; used with T874R1335; used in Y594R1201. L1413 Obsolete. Fedders heat pump; used with T874R1343; used in Y594R1219. L1421 Obsolete. Coleman heat pump; used with T874R1368;...
  • Page 85 Model Fig. Number L1678 Trol-A-Temp by Honeywell; gray color; used with T874R1707; used in Y594R1490. L1686 Trol-A-Temp by Honeywell; used with T874R1715; used in Y594R1508. L1702 Obsolete. Snyder General heat pump; part no. 654958B07; used with T874R1723 and C815A1005; used in Y594R1516.
  • Page 86 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number L1868 TRADELINE; includes two LEDs; used with T874R1988; used in Y594R1797; direct replacement for Evcon/Coleman Y594R1235 (T874R1368/ Q674L1421) Coleman part no. 3600-368. L1876 Obsolete. Amana part no. 10573902; includes two LEDs; used with T874R2002; used in Y594R1805.
  • Page 87 Obsolete. LSI; contains T874C1471, Q674B1257. C1322 Obsolete. Contains T874C1638, Q674L1561. C1330 Obsolete. Amana part no. D68535-21; contains T874C1059, Q674F1022. Both the thermostat and subbase must be replaced. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 10. Y594 Cross Reference. Trade Model Description Replacement T874A1036/ T874A1036/...
  • Page 88 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number C1348 Obsolete. Fiberglas; contains T874C1653, Q674S1000. C1355 Obsolete. Nordyne “Miller” part no. 9122250; contains T874C1695, Q674B1000. C1363 Obsolete. Nordyne “Intertherm” part no. 911100001; contains T874C1703, Q674B1000. C1371 Obsolete. California Economizer; contains T874C1802 and Q674G1005.
  • Page 89 T874G1428, Q674J1027. G1245 Obsolete. BDP part no. HH641502; contains T874G1451, Q674F1212. G1252 TRADELINE; contains T874G1246, Q674F1212. Both the thermostat and subbase must be replaced. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 10. Y594 Cross Reference. Trade Model Description Replacement T874D1165/ T874D1165/...
  • Page 90 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number G1294 Obsolete. LSI; contains T874G1378, Q674C1124. G1328 Obsolete. Addison part no. 8403-197; contains T874G1543, Q674F1345. G1344 Obsolete. Heat Controller part no. 7601-110B; contains T874G1469, Q674F1345. G1351 Obsolete. Luxaire part no. 026-00068-000; contains T874G1568, Q674J1126.
  • Page 91 T874J1002 or T874A1028 used with Q674L1074 or Q674L1637 (HH07AT175 or HH07AT165 used with HH93AZ186 or HH93AZ195). Both the thermostat and subbase must be replaced. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 10. Y594 Cross Reference. Trade Model Description Replacement...
  • Page 92 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number J1019 Obsolete. TRADELINE; automatic changeover; contains T874J1069 and Q674J1282; direct replacement for T874J1002 or T874J1028 used with Q674J1068 or Q674J1159 (HH07AT175 or HH07AT165 used with HH93AZ183 or HH93AZ196). Y594N N1007 Obsolete. Williamson part no. 75-189; contains T874N1008 and Q674F1196.
  • Page 93 Heil Quaker part no. 1060322; model no. TAXB004TW01; contains T874R1749 and Q674L1132. R1607 Obsolete. Keeprite THPC; contains T874R1814 and Q674L1132. Both the thermostat and subbase must be replaced. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 10. Y594 Cross Reference. Trade Model Description Replacement Remarks Y594R1292...
  • Page 94 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Model Fig. Number R1615 TRADELINE; contains T874R1822 and Q674L1710; replaces Y594R1326 (T874R1491/ Q674L1553). R1623 Obsolete. Rheem Universal Parts part no. 41- 20796-46; contains T874R1558 and Q674L1504. R1631 Rheem part no. 41-20796-29; contains T874R1442 and Q674L1504.
  • Page 95 Obsolete. Mammoth part no. 71117301; contains T874Y1005 and Q674E1353. Y1012 Obsolete. WaterFurnace logo; part no. TA21H03; contains T874Y1013 and Q674F1675. Both the thermostat and subbase must be replaced. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES Table 10. Y594 Cross Reference. Trade Model Description Replacement Y594R1797 See OEM for replacement.
  • Page 96: Wiring Diagrams

    T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES WIRING DIAGRAMS THERMOSTAT FALL H1 ANTICIPATOR H2 ANTICIPATOR FALL RISE C1 ANTICIPATOR C2 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. JUMPER RH, RC FOR SINGLE TRANSFORMER. Fig. 44. Schematic and hookup of T874A,B,C,D,E,F with Q674B. Used in standard applications.
  • Page 97 H1/C1 ANTICIPATOR FALL FALL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 47. Schematic and hookup of T874R with Q674B. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO SYSTEM SWITCH HEAT...
  • Page 98 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL H1 ANTICIPATOR ANTICIPATOR FALL RISE C1 ANTICIPATOR C2 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. CLOGGED FILTER, SERVICE SWITCH. Fig. 48. Schematic and hookup of T874D with Q674B. Used in standard applications.
  • Page 99 C1 ANTICIPATOR C1 RISE 1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 50. Schematic and hookup of T874G with Q674B. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH HEAT LED (RED)
  • Page 100 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL H1 ANTICIPATOR FALL H2 ANTICIPATOR RISE C1 ANTICIPATOR C2 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. FIELD WIRE JUMPER TO ALLOW SINGLE SYSTEM TRANSFORMER. B, O TERMINALS ON SOME MODELS.
  • Page 101 C1 ANTICIPATOR C2 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 54. Schematic and hookup of T874W with Q674B. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH AUTO SYSTEM SWITCH HEAT...
  • Page 102 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL H1 ANTICIPATOR H2 ANTICIPATOR FALL RISE C1 ANTICIPATOR C2 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. JUMPER RC, RH FOR SINGLE TRANSFORMER. B AND 5 TERMINALS AVAILABLE ON SOME MODELS.
  • Page 103 THERMOSTAT H1 ANTICIPATOR FALL FALL H2 ANTICIPATOR RISE C1 ANTICIPATOR RISE Fig. 58. Schematic and hookup of T874G with Q674D. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH COMPRESSOR CONTACTOR AUTO SYSTEM SWITCH OVERRIDE HEAT...
  • Page 104 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT ANTICIPATOR FALL RISE ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 59. Schematic and hookup of T874A with Q674Q. Used in fan coil applications. THERMOSTAT H1 ANTICIPATOR FALL FALL...
  • Page 105 HEAT COOL H1 ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 62. Schematic and hookup of T874F with Q674B. Used in wood/coal applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO HEAT SUBBASE SYSTEM COMPONENTS FAN RELAY AUX.
  • Page 106 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL H2 ANTICIPATOR FALL H1 ANTICIPATOR 1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 63. Schematic and hookup of T874F with Q674D. Used in wood/coal applications. THERMOSTAT ANTICIPATOR FALL...
  • Page 107 FALL FALL H2 ANTICIPATOR 1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 66. Schematic and hookup of T874A,D,F with Q674D. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE AUTO SYSTEM SWITCH HEAT COOL...
  • Page 108 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1/C1 ANTICIPATOR FALL FALL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 67. Schematic and hookup of T874R with Q674B. Used in heat pump applications. THERMOSTAT ANTICIPATOR FALL RISE RISE C1 ANTICIPATOR POWER SUPPLY.
  • Page 109 HEAT COOL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. FALL Fig. 70. Schematic and hookup of T874C with Q674S. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE CONT. COOL SUBBASE SERVICE LED (RED)
  • Page 110 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT ANTICIPATOR FALL FALL H2 ANTICIPATOR RISE C1 ANTICIPATOR C2 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. JUMPER RH, RC FOR SINGLE TRANSFORMER. Fig. 71. Schematic and hookup of T874A-D with Q674A. Used in standard applications.
  • Page 111 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. SERVICE LED ON SELECT MODELS. Fig. 74. Schematic and hookup of T874H with Q674C. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH AUTO SYSTEM...
  • Page 112 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT ANTICIPATOR H1 FALL RISE ANTICIPATOR THERMISTOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. MOMENTARY POSITION. SPRING RETURN TO "ON" UPON SWITCH RELEASE. FILTER LED ON SELECT MODELS. Fig. 75. Schematic and hookup of T874A with Q674C. Used in standard applications.
  • Page 113 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. JUMPER HONEYWELL SUPPLIED, FIELD INSTALLED. Fig. 78. Schematic and hookup of T874P with Q674C. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE RESET SWITCH LED (RED)
  • Page 114 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1 ANTICIPATOR FALL FALL RISE ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD RISE PROTECTION AS REQUIRED. SETBACK CONTACT ON Q674C1124. Fig. 79. Schematic and hookup of T874G,H with Q674C. Used in standard applications.
  • Page 115 AS REQUIRED. RISE JUMPER RC, RH FOR SINGLE TRANSFORMER. O AND B TERMINALS ON SELECTED MODELS. Fig. 82. Schematic and hookup of T874A,C,D with Q674E. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO SYSTEM SWITCH...
  • Page 116 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1 ANTICIPATOR FALL H2 ANTICIPATOR FALL RISE C1 ANTICIPATOR C2 ANTICIPATOR RISE Fig. 83. Schematic and hookup of T874G with Q674C. Used in standard applications. THERMOSTAT H1 ANTICIPATOR FALL H2 ANTICIPATOR FALL C1 ANTICIPATOR...
  • Page 117 C1 ANTICIPATOR RISE RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 86. Schematic and hookup of T874G with Q674E. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO SYSTEM SWITCH HEAT...
  • Page 118 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL H1 ANTICIPATOR H2 ANTICIPATOR FALL RISE C1 ANTICIPATOR RISE C2 ANTICIPATOR Fig. 87. Schematic and hookup of T874D with Q674E. Used in standard applications. THERMOSTAT ANTICIPATOR FALL FALL H2 ANTICIPATOR RISE C1 ANTICIPATOR...
  • Page 119 C1 ANTICIPATOR C2 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 90. Schematic and hookup of T874D with Q674G. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE AUTO SWITCH SYSTEM SWITCH FILTER...
  • Page 120 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT ANTICIPATOR FALL FALL H2 ANTICIPATOR RISE C1 ANTICIPATOR C2 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. JUMPER RH, RC FOR SINGLE TRANSFORMER. Fig. 91. Schematic and hookup of T874A-F,Q with Q674G. Used in standard applications.
  • Page 121 C1 ANTICIPATOR C2 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 94. Schematic and hookup of T874D with Q674G. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE NO FAN SWITCH SYSTEM SWITCH...
  • Page 122 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTATS FALL H1 ANTICIPATOR FALL H2 ANTICIPATOR POWER SUPPLY. PROVIDE DISCONECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 95. Schematic and hookup of T874F with Q674K. Used in wood/oil applications. THERMOSTAT FALL FALL H2 ANTICIPATOR...
  • Page 123 C2 ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. T874A IS SINGLE-STAGE (NO W2 OR Y2). Fig. 98. Schematic and hookup of T874D with Q674E. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO...
  • Page 124 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1 ANTICIPATOR FALL H2 ANTICIPATOR FALL RISE C1 ANTICIPATOR THERMISTER POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. MOMENTARY POSITION. SPRING RETURN TO "ON" UPON SWITCH RELEASE. H1 AND C1 ARE DPST SWITCHES.
  • Page 125 ANTICIPATOR FALL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 101. Schematic and hookup of T874R with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SYSTEM SWITCH AUTO SERVICE LED (RED) SWITCH AUTO H3 OFFSET 12 F FROM H2 FOR NIGHT SETBACK.
  • Page 126 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1/C1 ANTICIPATOR FALL FALL H2 ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. FIELD WIRE JUMPER TO ALLOW SINGLE SYSTEM TRANSFORMER. Fig. 102. Schematic and hookup of T874J,R with Q674L. Used in heat pump applications.
  • Page 127 OPTIONAL FIELD WIRE JUMPER TO CYCLE AUXILIARY HEAT RELAY H1 INSTEAD OF H2 (FASTER RESPONSE). Fig. 104. Schematic and hookup of T874R with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE COOL CHANGEOVER VALVE SWITCH...
  • Page 128 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1 ANTICIPATOR FALL FALL H2 ANTICIPATOR C1 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 105. Schematic and hookup of T874C with Q674L. Used in heat pump applications.
  • Page 129 FALL FALL ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 108. Schematic and hookup of T874R with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO SYSTEM SWITCH EM. HT.
  • Page 130 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1/ C1 ANTICIPATOR FALL RESET HEATER FALL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 109. Schematic and hookup of T874R with Q674L. Used in heat pump applications. 60-2485—8 SUBBASE...
  • Page 131 AND OVERLOAD PROTECTION AS REQUIRED. REMOVE FACTORY INSTALLED V-VR JUMPER WHEN CONNECTING A TWO TRANSFORMER SYSTEM. Fig. 110. Schematic and hookup of T87C,R with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE COMPRESSOR CONTACTOR FAN SWITCH...
  • Page 132 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT RESET HEATER H1/ C1 ANTICIPATOR FALL FALL ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 111. Schematic and hookup of T874R with Q674L. Used in heat pump applications. 60-2485—8...
  • Page 133 ANTICIPATOR ANTICIPATOR FALL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 112. Schematic and hookup of T874R with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO COMPRESSOR FAILURE SYSTEM SWITCH EM.
  • Page 134 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1/C1 ANTICIPATOR FALL FALL H2 ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 113. Schematic and hookup of T874R with Q674L. Used in heat pump applications. 60-2485—8 SUBBASE SWITCH...
  • Page 135 ANTICIPATOR ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 114. Schematic and hookup of T874D with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH AUTO SYSTEM SWITCH EM. HT.
  • Page 136 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1/C1 ANTICIPATOR FALL ANTICIPATOR FALL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. AUXILIARY HEAT LED AVAILABLE ON SOME MODELS. Fig. 115. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
  • Page 137 OPTIONAL FIELD WIRE JUMPER TO CYCLE AUXILIARY HEAT RELAY WITH H1 INSTEAD OF H2 (FASTER RESPONSE). Fig. 116. Schematic and hookup of T874R with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO EM. HT.
  • Page 138 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL H1 ANTICIPATOR H2 ANTICIPATOR FALL RISE C1 ANTICIPATOR C2 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. OPTIONAL ECONOMIZER HOOKUP (DOTTED LINES). Fig. 117. Schematic and hookup of T874D with Q674L. Used in heat pump applications.
  • Page 139 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. OPTIONAL ECONOMIZER HOOKUP (DOTTED LINES). Fig. 118. Schematic and hookup of T874W with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SYSTEM COMPONENTS DEFROST RELAY ECONOMIZER...
  • Page 140 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT RESET HEATER H2 ANTICIPATOR FALL ANTICIPATOR H1 ANTICIPATOR FALL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 119. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
  • Page 141 SWITCH ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 121. Schematic and hookup of T874C with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO EM. HT. LED (RED) AUX.
  • Page 142 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL H1/C1 ANTICIPATOR FALL ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 122. Schematic and hookup of T874R with Q674L. Used in heat pump applications. 60-2485—8 SUBBASE SWITCH AUTO...
  • Page 143 CONNECT CHANGEOVER RELAY TO B FOR HEAT CHANGEOVER, TO O FOR COOL CHANGEOVER. Fig. 123. Schematic and hookup of T874R with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE RTD 1 EM. HT. LED (RED) AUX.
  • Page 144 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL ANTICIPATOR ANTICIPATOR FALL RISE C1 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. ON MODELS INCLUDING EXTERNAL JUMPER, W2=W1 AND L=F. Fig. 124. Schematic and hookup of T874J with Q674L. Used in heat pump applications.
  • Page 145 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. TERMINAL LABELED C/X ON SOME MODELS. W3 TERMINAL AVAILABLE ON SOME MODELS ONLY. Fig. 125. Schematic and hookup of T874R with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SYSTEM COMPONENTS SUBBASE EM. HT.
  • Page 146 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1 ANTICIPATOR FALL FALL H2 ANTICIPATOR C1 ANTICIPATOR RISE RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. N.O. SWITCH INSTALLER ADDED, TO LIGHT EM. HT. LED WHEN COMPRESSOR OPERATION IS NOT NORMAL.
  • Page 147 FALL RISE ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 129. Schematic and hookup of T874G with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SERVICE LED (RED) SWITCH AUTO AUX.
  • Page 148 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL H1/C1 ANTICIPATOR FALL H2 ANTICIPATOR RESET POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. FACTORY-INSTALLED JUMPER. Fig. 130. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
  • Page 149 FALL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. FOR Q674L1454, IS "OFF". Fig. 131. Schematic and hookup of T874R with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE AUTO SWITCH SYSTEM SWITCH SUPL.
  • Page 150 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL H1/C1 ANTICIPATOR FALL ANTICIPATOR RESET POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. REMOVE JUMPER FOR INDEPENDENT CONTROL OF W1 AND E TERMINALS. Fig. 132. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
  • Page 151 EM. HT. HEAT COOL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 134. Schematic and hookup of T874R with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE AUX. HT. LED (GREEN) COMP. FAILURE EM.
  • Page 152 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1/C1 ANTICIPATOR RESET HEATER FALL H2 ANTICIPATOR FALL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 135. Schematic and hookup of T874R with Q674L. Used in heat pump applications. THERMOSTAT...
  • Page 153 EM. HT. HEAT COOL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 137. Schematic and hookup of T874R with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE AUX. HT. LED (GREEN) COMP. FAILURE EM.
  • Page 154 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL H1 ANTICIPATOR H2 ANTICIPATOR FALL RISE C1 ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. FIELD REMOVABLE JUMPER Fig. 138. Schematic and hookup of T874L with Q674B. Used in heat pump applications.
  • Page 155 CONNECT CHANGEOVER RELAY TO 'O' TERMINAL FOR CHANGEOVER IN COOLING OR TO 'B' TERMINAL FOR CHANGEOVER IN HEATING. Fig. 140. Schematic and hookup of T874W with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE AUX. HT.
  • Page 156 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL ANTICIPATOR FALL ANTICIPATOR RISE ANTICIPATOR ANTICIPATOR RISE Fig. 141. Schematic and hookup of T874C with Q674F. Used in standard applications. THERMOSTAT FALL H1 ANTICIPATOR H2 ANTICIPATOR FALL RISE ANTICIPATOR ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
  • Page 157 H2 FALL RISE SYSTEM SWITCH C1 ANTICIPATOR SUPL. HT. RISE Fig. 144. Schematic and hookup of T874J with Q674J. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO SYSTEM SWITCH AUTO AUX. HT. LED (RED) POWER SUPPLY.
  • Page 158 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT ANTICIPATOR FALL FALL ANTICIPATOR FALL C1 ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND RISE OVERLOAD PROTECTION AS REQUIRED. Fig. 145. Schematic and hookup of T874G with Q674F. Used in heat pump applications. THERMOSTAT...
  • Page 159 H2 ANTICIPATOR RISE ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 148. Schematic and hookup of T874G with Q674F. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO SERVICE LED (RED)
  • Page 160 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL H1 ANTICIPATOR FALL ANTICIPATOR RISE RISE ANTICIPATOR ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. OPTIONAL FIELD WIRE JUMPER TO ALLOW SINGLE SYSTEM TRANSFORMER. FOR Q674F1048, DELETE C2 STAGE.
  • Page 161 RISE RISE ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 150. Schematic and hookup of T874G with Q674F. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE COMPRESSOR CONTACTOR FAN SWITCH AUTO RELAY...
  • Page 162 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT ANTICIPATOR FALL ANTICIPATOR FALL RISE ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. RISE OPTIONAL FIELD WIRE JUMPER TO CYCLE W2 WITH H1 IN EM. HT. (FASTER RESPONSE). Fig. 151. Schematic and hookup of T874G with Q674F. Used in heat pump applications.
  • Page 163 RISE RISE C1 ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 153. Schematic and hookup of T874G with Q674F. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH AUTO SYSTEM SWITCH EM.
  • Page 164 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1 ANTICIPATOR FALL H2 ANTICIPATOR FALL H1 ANTICIPATOR RISE RISE Fig. 154. Schematic and hookup of T874G with Q674F. Used in heat pump applications. 60-2485—8 SUBBASE SWITCH AUTO SYSTEM SWITCH EM. HT. HEAT...
  • Page 165 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. W3 TERMINAL ON SELECT MODELS. Fig. 155. Schematic and hookup of T874G with Q674F. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO AUX. HT.
  • Page 166 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT ANTICIPATOR FALL FALL H2 ANTICIPATOR RISE C1 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 156. Schematic and hookup of T874G with Q674F. Used in heat pump applications.
  • Page 167 RISE C1 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 158. Schematic and hookup of T874G with Q674F. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO SYSTEM SWITCH EM. HT.
  • Page 168 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1 ANTICIPATOR H1 FALL FALL H2 ANTICIPATOR RISE C1 ANTICIPATOR RISE Fig. 159. Schematic and hookup of T874G with Q674J. Used in heat pump applications. THERMOSTAT FALL H1 ANTICIPATOR H2 ANTICIPATOR FALL RISE...
  • Page 169 C1 ANTICIPATOR RISE RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 161. Schematic and hookup of T874G with Q674J. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE COOL CHANGEOVER VALVE SWITCH AUTO SYSTEM SWITCH SUPL.
  • Page 170 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THEROMSTAT FALL H1 ANTICIPATOR FALL RESET HEATER RISE RISE ANTICIPATOR Fig. 162. Schematic and hookup of T874G with Q674J. Used in heat pump applications. 60-2485—8 SUBBASE FAN SWITCH AUTO AUX. HT. LED (GREEN) SYSTEM SWITCH EM.
  • Page 171 H2 HAS 10¡F FIXED SETBACK FROM H1 ON T874G1485, 0-12¡F ADJUSTABLE ON T874G1535. RESET IN MOMENTARY POSITION, SPRING RETURN TO OFF UPON SWITCH RELEASE. Fig. 163. Schematic and hookup of T874G with Q674C. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE (HOT) SWITCH AUTO...
  • Page 172 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT ANTICIPATOR FALL RISE ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. R-L JUMPER SUPPLIED BY HONEYWELL. Fig. 164. Schematic and hookup of T874H with Q674C. Used in standard applications.
  • Page 173 C2 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 166. Schematic and hookup of T874D with Q674F. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE AUX. HT. LED (GREEN) EM. HT. LED...
  • Page 174 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1 ANTICIPATOR FALL ANTICIPATOR FALL FALL CHANGEOVER ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. RISE Fig. 167. Schematic and hookup of T874G with Q674F. Used in heat pump applications.
  • Page 175 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. REMOVE JUMPER WHEN W1 RELAY IS USED. FACTORY-INSTALLED JUMPER. Fig. 168. Schematic and hookup of T874R with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO EM. HT.
  • Page 176 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL H1 ANTICIPATOR ANTICIPATOR FALL RISE C1 ANTICIPATOR RISE Fig. 169. Schematic and hookup of T874G with Q674F. Used in heat pump applications. 60-2485—8 SUBBASE FAN SWITCH AUTO SYSTEM SWITCH EM. HT. HEAT EM.
  • Page 177 ON SOME MODELS, Y TERMINAL MAY BE LABELED Y1. EMERGENCY HEAT RUNS CONTINUOUSLY WHEN SWITCH IN IN EM. HT. POSITION. Fig. 170. Schematic and hookup of T874G with Q674F. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH...
  • Page 178 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL H1 ANTICIPATOR H2 ANTICIPATOR FALL RISE C1 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. EXTERNAL JUMPER SUPPLIED BY HONEYWELL. Fig. 171. Schematic and hookup of T874J with Q674J. Used in heat pump applications.
  • Page 179 RISE RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. REMOVABLE JUMPER. Fig. 174. Schematic and hookup of T874G with Q674J. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO FAULT (RED) SYSTEM...
  • Page 180 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1 ANTICIPATOR FALL ANTICIPATOR FALL C1 ANTICIPATOR RISE RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 175. Schematic and hookup of T874G with Q674J. Used in heat pump applications.
  • Page 181 H2 ANTICIPATOR RISE C1 ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 178. Schematic and hookup of T874N with Q674F. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH RESET LED (RED)
  • Page 182 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT ANTICIPATOR FALL FAN SWITCH ANTICIPATOR FALL RISE ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 179. Schematic and hookup of T874N with Q674F. Used in heat pump applications. 60-2485—8...
  • Page 183 C2 ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. FILTER LED ON SOME MODELS. Fig. 180. Schematic and hookup of T874A,D with Q674J. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SYSTEM COMPONENTS R-11 R-11...
  • Page 184 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL FALL FALL ANTICIPATOR RISE ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 181. Schematic and hookup of T874K with Q674C. Used in heat pump applications. THERMOSTAT H1/C ANTICIPATOR...
  • Page 185 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 184. Schematic and hookup of T874A,F with Q674G. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SYSTEM COMPONENTS AUTO O. D. S. EM. HT.
  • Page 186 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT ANTICIPATOR FALL ANTICIPATOR FALL RISE ANTICIPATOR ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 185. Schematic and hookup of T874D with Q674E. Used in standard applications. THERMOSTAT FALL...
  • Page 187 ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 188. Schematic and hookup of T874D with Q674G. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SYSTEM COMPONENTS HEAT RELAY 2 HEAT RELAY 1 HI SPEED...
  • Page 188 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL FALL Fig. 189. Schematic and hookup of T874F with Q674D. Used in standard applications. THERMOSTAT RESET ANTICIPATOR FALL ANTICIPATOR FALL RISE ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
  • Page 189 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. MOMENTARY POSITION. SPRING RETURN TO "ON" UPON SWITCH RELEASE. Fig. 192. Schematic and hookup of T874D with Q674C. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SYSTEM COMPONENTS "Z" RELAY...
  • Page 190 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT ANTICIPATOR FALL FALL H2 ANTICIPATOR RISE C1 ANTICIPATOR C2 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. JUMPER RH, RC FOR SINGLE TRANSFORMER. Fig. 193. Schematic and hookup of T874D with Q674E. Used in standard applications.
  • Page 191 RISE C1 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 196. Schematic and hookup of T874G with Q674J. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH AUTO SYSTEM SWITCH EM.
  • Page 192 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL FALL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. FIELD REMOVABLE JUMPER. Fig. 197. Schematic and hookup of T874R with Q674L. Used in heat pump applications. THERMOSTAT FALL H1 ANTICIPATOR...
  • Page 193 FALL H1 ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 200. Schematic and hookup of T874R with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH AUTO AUX. HT. LED...
  • Page 194 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT RESET ANTICIPATOR RISE C1 ANTICIPATOR RISE H1 ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 201. Schematic and hookup of T874R with Q674L. Used in heat pump applications. THERMOSTAT...
  • Page 195 LED IS NOT LABELED. JUMPER W2 TO X FOR AUXILIARY HEAT INDICATION. JUMPER E TO X FOR EMERGENCY HEAT INDICATION. CONNECT SYSTEM MONITOR TO X TO IDENTIFY WHEN SYSTEM NEEDS TO BE CHECKED. Fig. 204. Schematic and hookup of T874D with Q674F. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH AUTO...
  • Page 196 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1 ANTICIPATOR FALL RISE C1 ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. RISE LEDS ON SOME MODELS. Fig. 205. Schematic and hookup of T874H with Q674C. Used in heat pump applications.
  • Page 197 H1 ANTICIPATOR ANTICIPATOR FALL RISE C1 ANTICIPATOR C2 ANTICIPATOR RISE Fig. 208. Schematic and hookup of T874D with Q674D. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH AUTO SUPL. HT. LED (RED) SYSTEM SWITCH SUPL. HT.
  • Page 198 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1/C1 ANTICIPATOR RISE H2 ANTICIPATOR FALL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 209. Schematic and hookup of T874R with Q674L. Used in heat pump applications. THERMOSTAT FALL H1 ANTICIPATOR...
  • Page 199 H1 ANTICIPATOR ANTICIPATOR FALL RISE C1 ANTICIPATOR C2 ANTICIPATOR RISE Fig. 212. Schematic and hookup of T874A with Q674E. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH AUTO SYSTEM SWITCH AUX. HT. (GREEN) EM. HT.
  • Page 200 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1 ANTICIPATOR FALL H2 ANTICIPATOR FALL RISE C1 ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 213. Schematic and hookup of T874L with Q674C. Used in heat pump applications.
  • Page 201 H1 ANTICIPATOR C1 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 214. Schematic and hookup of T874A with Q674B. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SYSTEM SWITCH HEAT COOL SWITCH...
  • Page 202 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1 ANTICIPATOR FALL H2 ANTICIPATOR FALL RISE C1 ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 215. Schematic and hookup of T874L with Q674B. Used in heat pump applications.
  • Page 203 AUTO RISE C1 ANTICIPATOR POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 217. Schematic and hookup of T874N with Q674C. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO AUX. HT. (YELLOW)
  • Page 204 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1/C1 ANTICIPATOR FALL ANTICIPATOR FALL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. TERMINAL LABELED C/X ON SOME MODELS. W3 TERMINAL AVAILABLE ON SOME MODELS ONLY. Fig. 218. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
  • Page 205 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. MOMENTARY POSITION. SPRING RETURN TO "ON" UPON SWITCH RELEASE. H2 OFFSET 12 F FROM H1. Fig. 219. Schematic and hookup of T874C with Q674C. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SYSTEM SWITCH AUTO...
  • Page 206 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL ANTICIPATOR FALL ANTICIPATOR FALL RISE RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. MOMENTARY POSITION. SPRING RETURN TO "ON" UPON SWITCH RELEASE. Fig. 220. Schematic and hookup of T874W with Q674C. Used in standard applications.
  • Page 207 ANTICIPATOR RISE ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 223. Schematic and hookup of T874S with Q674F. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH AUTO MALFUNCTION SYSTEM...
  • Page 208 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL ANTICIPATOR ANTICIPATOR FALL RISE RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 224. Schematic and hookup of T874A,D with Q674E. Used in standard applications. 60-2485—8 SUBBASE SWITCH AUTO...
  • Page 209 ANTICIPATOR FALL RISE RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 225. Schematic and hookup of T874D with Q674C. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SYSTEM SWITCH AUTO SERVICE LED (RED)
  • Page 210 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL ANTICIPATOR ANTICIPATOR FALL RISE RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 226. Schematic and hookup of T874G with Q674G. Used in standard applications. 60-2485—8 SUBBASE SERVICE LED (RED)
  • Page 211 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. W1 - Y1 JUMPER IS Y TERMINAL; REMOVE JUMPER WHEN W1 RELAY IS USED. Fig. 227. Schematic and hookup of T874G with Q674F. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO AUX.
  • Page 212 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT SWITCH FALL H1/C1 ANTICIPATOR H2 ANTICIPATOR FALL EM. HT. RESET POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. REMOVABLE JUMPER (INSTALLED). Fig. 228. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
  • Page 213 FALL ANTICIPATOR FALL POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 230. Schematic and hookup of T874R with Q674L. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SWITCH AUTO SERVICE LED (RED) AUX. HT.
  • Page 214 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT ANTICIPATOR FALL H2 ANTICIPATOR FALL ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. ONLY TERMINAL B OR O TO BE USED. 0.8A MAX. RISE Fig. 231. Schematic and hookup of T874G with Q674F. Used in heat pump applications.
  • Page 215 COOL ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 234. Schematic and hookup of T874G with Q674B. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE SYSTEM COMPONENTS AUTO SWITCH EM. HT.
  • Page 216 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT H1 ANTICIPATOR FALL ANTICIPATOR FALL RISE ANTICIPATOR CHANGEOVER RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 235. Schematic and hookup of T874G and Q674F. Used in heat pump applications.
  • Page 217 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. FACTORY INSTALLED JUMPER BETWEEN TERMINALS W1 AND Y1. Fig. 238. Schematic and hookup of T874C with Q674F. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH...
  • Page 218 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT ANTICIPATOR FALL FALL RESET POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 239. Schematic and hookup of T874R with Q674L. Used in heat pump applications. THERMOSTAT ANTICIPATOR FALL RISE ANTICIPATOR POWER SUPPLY.
  • Page 219 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. OVERRIDE IS MOMENTARY POSITION. SPRING RETURN TO (OFF) UPON SWITCH RELEASE. Fig. 242. Schematic and hookup of T874G with Q674C. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH AUTO SUPL. HEAT...
  • Page 220 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL H1 ANTICIPATOR ANTICIPATOR FALL RISE C1 ANTICIPATOR RISE Fig. 243. Schematic and hookup of T874G with Q674F. Used in heat pump applications. THERMOSTAT ANTICIPATOR FALL ANTICIPATOR FALL ANTICIPATOR RISE RISE 1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
  • Page 221 H2 ANTICIPATOR FALL RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 246. Schematic and hookup of T874C with Q674G. Used in standard applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH AUTO SYSTEM SWITCH EM. HT.
  • Page 222 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL H1 ANTICIPATOR H2 ANTICIPATOR FALL H3 ANTICIPATOR FALL RESET RISE C1 ANTICIPATOR C2 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. CONNECT CHANGEOVER RELAY TO 'O' TERMINAL FOR CHANGEOVER IN COOLING OR TO 'B' TERMINAL FOR CHANGEOVER IN HEATING.
  • Page 223 RISE ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. Fig. 248. Schematic and hookup of T874Y with Q674F. Used in heat pump applications. T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES SUBBASE FAN SWITCH AUTO AUX. HT. LED (RED)
  • Page 224 T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES THERMOSTAT FALL H1 ANTICIPATOR FALL H2 ANTICIPATOR RISE C1 ANTICIPATOR C2 ANTICIPATOR RISE POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. FIELD WIRE JUMPER TO ALLOW SINGLE SYSTEM TRANSFORMER. Fig. 249. Schematic and hookup of T874C with Q674B. Used in heat pump applications.

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Q674