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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
113 60-2485—8
Fig. 77. Schematic and hookup of T874K with Q674C. Used in heat pump applications.
Fig. 78. Schematic and hookup of T874P with Q674C. Used in heat pump applications.
C1
RISE
H1
H2
CO
FALL
FALL
FALL
L1
(HOT)
L2
1
1
2
L1
(HOT)
L2
1
2
POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
JUMPER RH AND RC FOR SINGLE
TRANSFORMER SYSTEM.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
H1 ANTICIPATOR
C1
ANTICIPATOR
SYSTEM
SWITCH
FAN
SWITCH
AUTO
ON
OFF
AUTO
FAN RELAY
HEAT CHANGEOVER
VALVE
COMPRESSOR
CONTACTOR
M4729
1
3
4
6
8
9
10
Y1
O
RC
B
W3
W2
W1
RH
G
X1
RESET
LED (RED)
"O" RELAY
"B" RELAY
HEAT RELAY 1
HEAT RELAY 2
B
1
THERMOSTAT
SUBBASE SYSTEM COMPONENTS
C
G
R
H1
ANTICIPATOR
C1
RISE
H2
FALL
C1
ANTICIPATOR
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
JUMPER HONEYWELL SUPPLIED, FIELD INSTALLED.
W
1
4
9
10
3
8
AUTO
ON
FAN
SWITCH
SYSTEM
SWITCH
OFF
COMPRESSOR
CONTACTOR
AUTO
Y
L1
(HOT)
1
L2
2
FAN RELAY
SETBACK
CONTACT
M7026
HEAT
CHANGEOVER
VALVE
L
S
P
2
REVERSING
VALVE
JUMPER
2
H1
RISE
CO
5
6
OVERRIDE