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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8108
Fig. 67. Schematic and hookup of T874R with Q674B. Used in heat pump applications.
Fig. 68. Schematic and hookup of T874P with Q674B. Used in heat pump applications.
M5998
H2
FALL
H1
FALL
C1
L1
(HOT)
L2
1
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
H1/C1 ANTICIPATOR
FAN SWITCH
AUTO
ON
SYSTEM
SWITCH
HEAT
OFF
COOL
COMPRESSOR
CONTACTOR
AUX. HT. RELAY
HEAT CHANGEOVER
VALVE
FAN RELAY
6
5
4
3
2
1
X
G
R
B
W2
Y
H2
FALL
H1
RISE
CO
L1
(HOT)
L2
1
C1
RISE
COMPRESSOR CONTACTOR
FAN RELAY
CLOSED-DAY
OPEN-NITE
B RELAY
SERVICE
LED (RED)
OVERRIDE
LED (RED)
FAN
SWITCH
AUTO
ON
H1
ANTICIPATOR
SYSTEM SWITCH
JUMPER
COOL CHANGEOVER VALVE
OVERRIDE
HEAT
OFF
C1 ANTICIPATOR
1
2
3
4
5
6
8
9
10
W
P
S
X
L
B
R
C
G
Y
POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
JUMPER HONEYWELL SUPPLIED, FIELD INSTALLED.
H2 MAKE OFFEST 8˚ F BELOW H1 MAKE.
3
2
1
2
3
M101A
THERMOSTAT
SUBBASE SYSTEM COMPONENTS
T
COOL
COMPRESSOR
FAULT