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THERMOSTAT
H1
C1
H1/C1 ANTICIPATOR
FALL
FALL
H2
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
Fig. 7. Internal schematic and typical hookup of T874R Thermostat with
Q674B Subbase in heat pump system with changeover in heating.
THERMOSTAT
H1
FALL
H1 ANTICIPATOR
H2
H2
FALL
ANTICIPATOR
C1
RISE
C1 ANTICIPATOR
C2 ANTICIPATOR
C2
RISE
Fig. 8. Internal schematic and typical hookup of T874D Thermostat with
T874A,D,R THERMOSTATS AND Q674B,D,F,Q SUBBASES
SUBBASE
1
FAN SWITCH
2
AUTO
ON
3
4
5
SYSTEM
SWITCH
HEAT
6
OFF
COOL
SUBBASE
1
4
5
6
8
9
10
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
2
RC-RH REMOVABLE JUMPER WHEN SPECIFIED.
11
Q674D Subbase with automatic changeover.
X
G
R
B
W2
Y
NO
FAN
SWITCH
NO
SYSTEM
SWITCH
5
SYSTEM COMPONENTS
FAN RELAY
L1
(HOT)
1
L2
HEAT CHANGEOVER
VALVE
AUX. HT. RELAY
COMPRESSOR
CONTACTOR
SYSTEM COMPONENTS
HEAT RELAY 1
W1
HEAT RELAY 2
W2
RH
2
RC
Y2
COMPRESSOR
CONTACTOR 2
Y1
COMPRESSOR
CONTACTOR 1
M5998
L1
(HOT)
L2
1
1
L1
(HOT)
L2
M2986
69-0107—2
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