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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
71
60-2485—8
Table 9. Q674 Subbase Cross Reference.
Model
Number
Fig.
No.
Description
Q674 Trade
Replacement
Remarks
Q674A
System: HEAT-AUTO-COOL; Fan: AUTO-ON
A1001
71
Standard OEM.
Q674A1019
A1019
71
TRADELINE® model; used with T874A-D.
Q674A1019
A1035
71
Obsolete. Trane part no. BAS-0435; used with T874A-D.
Q674A1019
A1043
71
Honeywell logo; TRADELINE model;
Q674A1019
A1050
71
Obsolete. Standard OEM.
Q674A1043
Q674B
System: HEAT-OFF-COOL; Fan: AUTO-ON
B1000
45
Standard OEM; used with T874C1570, C1695, C1703,
D1843; used in Y594C1363.
Q674B1034
B1018
44
Standard OEM; used with T874B1035, D1082; used in
Y594B1026, D1016.
Q674B1018
B1026
45
Obsolete. System: HEAT-OFF-RESET-COOL.
Q674B1034
B1034
45
TRADELINE
Q674B1034
B1042
47
Obsolete. Used with T874R1004, R1509; used in
Y594R1029, R1334.
Y594R1243
a
Wiring differences (old=new):
W1=W2.
B1059
45
Obsolete. Factory installed RC-RH jumper; used with
T874C1059; used in Y594C1256.
Q674B1034
Field wire RC-RH.
B1075
46
Auto fan in heating and cooling mode; used with
T874B1035, C1000, D1082; used in Y594D1040.
Q674B1075
B1083
51
Obsolete. Carrier part no. HH93AZ178; factory
installed RC-RH jumper.
Q674B1075
a
One system transformer only.
B1091
45
Obsolete. Carrier part no. HH93AZ184; factory
installed RC-RH jumper.
Q674B1034
B1109
47
Obsolete. Addison heat pump; used with T874R1012.
Y594R1243
a
Wiring differences (old=new):
W1=W2.
B1117
44
Obsolete. Carrier part no. HH93AZ180; factory
installed RC-RH jumper.
Q674B1018
a
B1125
53
Obsolete. York part no. 2TB04700324A; used with
T874D1041.
Q674B1075
a
Jumper RC-RH; replacement
has no LOCKOUT LED.
B1133
48
Obsolete. Includes FILTER LED; used with
T874D1082; used in Y594D1156.
Q674B1018
B1141
51
Trane part no. BAY28X185; automatic fan operation in
heat and cool mode.
Q674B1075
Set T874 H1 anticipator for
combined load of heat relay
and fan relay.
B1158
50
Obsolete. Used with T874G1071.
T874C1018/
Q674B1018
a
W1-Y1 and RH-RC jumpers
required.
B1166
249
Carrier part no. HH93AZ179; factory installed RC-RH
jumper; LOCKOUT LED; used with T874C1075
(HH07AT170).
Y594C1421 or
Q674B1075
a
Replacement only requires
one transformer and has no
LOCKOUT LED.
B1190
52
Obsolete. Wards special; factory installed RH-RC and
F-W3 jumpers; used with T874C1372.
Gas Furnace:
Q674B1034
Electric Furnace:
Q674B1075
B1208
187
Obsolete. Used with T874C1422.
None
B1216
54
Used with T874W1015 and C815A1005; used in
Y594W1014.
Q674B1216
B1224
49
Obsolete. Lennox part no. 25F7301; four LEDs; used
with T874C1430.
Q674B1034
Replacement has no LEDs.
a
Both the thermostat and subbase must be replaced.