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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
221 60-2485—8
Fig. 245. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
Fig. 246. Schematic and hookup of T874C with Q674G. Used in standard applications.
H1
FALL
L1
(HOT
)
L2
1
1
2
2
POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
TERMINAL LABELED C/X ON SOME MODELS.
H1/C1
ANTICIPATOR
FAN SWITCH
AUTO
ON
SYSTEM
SWITCH
HEAT
OFF
COOL
2
3
4
6
O
W2
X
E
L
B
R
G
Y
AUX. HT. RELAY
FAN RELAY
EM. HT. RELAY
B RELAY
M7718
THERMOSTAT SUBBASE SYSTEM COMPONENTS
COMPRESSOR
CONTACTOR
EM. HT.
EM. HT.
LED (RED)
AUX. HT.
LED (GREEN)
COOL CHANGEOVER
VALVE
H2
C1
FALL
H2
ANTICIPATOR
W2
W1
HEAT RELAY 1
OFF
AUTO
SYSTEM
SWITCH
1
M7717
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
L1
(HOT
)
L2
1
Y2
HEAT RELAY 2
RH
RC
Y1
COOL CHANGEOVER
VALVE
L1
(HOT
)
L2
1
H1 ANTICIPATOR
H2 ANTICIPATOR
C1
RISE
H1
FALL
FALL
H2
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
NO FAN
SWITCH
1
4
6
8
10
11
9