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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
97 60-2485—8
Fig. 46. Schematic and hookup of T874A,B,D with Q674B. Used in standard applications.
.
Fig. 47. Schematic and hookup of T874R with Q674B. Used in heat pump applications.
H1
FALL
W1
W2
O
G
Y2
Y1
HEAT RELAY 2
HEAT RELAY 1
HEAT
OFF
COOL
SYSTEM
SWITCH
H1 ANTICIPATOR
C1 ANTICIPATOR
AUTO
ON
FAN
SWITCH
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
M2904
B
HEAT CHANGEOVER
VALVE
COOL
CHANGEOVER
VALVE
FAN RELAY
COMPRESSOR
CONTACTOR 2
COMPRESSOR
CONTACTOR 1
1
4
6
8
9
10
11
H2
FALL
C2 ANTICIPATOR
RISE
RISE
C1
C2
L1
(HOT)
L2
1
R
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
H2 ANTICIPATOR
L1
(HOT)
L2
1
COOL
HEAT
FALL
O
G
R
W1
Y
H1/C1
ANTICIPATOR
H2
SYSTEM
SWITCH
FAN RELAY
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
M2906
OFF
COOL CHANGEOVER
VALVE
H1
FALL
C1
FAN
SWITCH
AUTO
ON
THERMOSTAT
SUBBASE SYSTEM COMPONENTS
1
2
3
4
5
6
AUX. HT.
RELAY
COMPRESSOR
CONTACTOR