T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
79 60-2485—8
F1360 167 Obsolete. Rheem part no. 41-20797-17; AUX HEAT
and EM HEAT LEDs; used with T874G1493.
Y594G1526a
F1378 195 Obsolete. Includes EM HEAT and AUX HEAT LEDs;
used with T874G1501.
Y594G1252aWiring differences (old=new):
L1=L; changeover in cooling
only.
F1394 139 Obsolete. Nepco heat pump; HEAT PUMP and AUX
HEAT LEDs; System: AUX HEAT-HEAT PUMP-2
STAGE HEAT-OFF-COOL; used with T874D1595.
T874D1165/
Q674B1018a
Replacement has HEAT-OFF-
COOL system switching and
no LEDs.
F1402 169 Obsolete. Coleman heat pump; two LEDs; used with
T874G1576; used in Y594G1377.
Y594G1633a
F1410 170 Used with T874G1246, G1915; used in Y594G1393. Y594G1393a
F1428 199 Obsolete. Used with T874G1600; used in Y594G1401. Y594G1419aWiring differences (old=new):
jumper W1-Y1.
F1436 167 Includes AUX HEAT and EM HEAT LEDs; changeover
in heating mode; used with T874G1626; used in
Y594G1526.
None
F1444 227 Includes AUX HEAT, EM HEAT and CHECK LEDs;
used with T874G1642; used in Y594G1419.
Y594G1419a
F1451 204 Obsolete. York part no. 2TB047700524A; one LED and
field selectable inserts.
Q674F1012 Wiring differences (old=new):
X2=X; X1=B.
F1477 227 TRADELINE; gray color; used with T874G1741,
G1824; used in Y594G1476, G1534.
Y594G1476a
F1485 211 Trol-A-Temp by Honeywell; changeover is provided by
Trol-A-Temp zone panel; used with T874G1758; used
in Y594G1492.
None See Trol-A-Temp.
F1501 223 Obsolete. Carrier two-speed compressor heat pump;
used with T874S1001.
T8611M2025
(programmable)
Includes night setback.
F1519 231 Obsolete. Nordyne; used with T874G1832, G1840;
used in Y594G1542, G1559.
Y594G1252aReplacement has auto
changeover in cooling mode
only.
F1535 229 Obsolete. Lennox heat pump; gray color; used with
T874G1857; used in Y594G1583.
Y594G1161aWiring differences (old=new):
E=X2, C=B, L=F.
F1543 204 Obsolete. TRADELINE Q674F1022 Wiring differences (old=new):
X2=X, X1=B.
F1550 243 Obsolete. Amana part no. 10573901; includes two
LEDs; used with T874G1899; used in Y594G1591.
Y594G1633
F1568 155 Obsolete. Gray color; includes two LEDs; used with
only T874G1931.
Y594G1476 Y1-W1 jumper required.
F1584 169 TRADELINE; includes two LEDs; used with
T874G1972; used in Y594G1633. Direct replacement
for Coleman/Evcon Y594G1377 (T874G1576/
Q674D1402); Coleman part no. 3600-373.
Y594G1633a
F1592 238 Heat Controller; Fan: AUTO-ON; System: AUX HEAT-
HEAT PUMP- 2 STAGE HEAT-OFF-COOL; includes
two LEDs; used with T874C1844; used in Y594C1413.
Y594R1425 E-W2 jumper required; system
switch: EM.HT.-HEAT-OFF-
COOL.
F1600 169 Obsolete. Amana part no. 10573903; includes two
LEDs; used with T874G1980; used in Y594G1641.
Y594G1633 Wiring differences (old=new);
W3=W2.
F1634 139 Standard OEM; System: AUX HEAT-HEAT PUMP-
2 STG HEAT-OFF-COOL; includes two LEDs; used
with T874D2155.
Y594G1716
F1667 155 WaterFurnace logo; part no. TA21H03; System: OFF-
AUTO-HEAT-EM HT; includes two LEDs; used with
T874G2046.
Y594G1716
Table 9. Q674 Subbase Cross Reference.
Model
Number
Fig.
No. Description
Q674 Trade
Replacement Remarks
aBoth the thermostat and subbase must be replaced.