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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
215 60-2485—8
Fig. 233. Schematic and hookup of T874W with Q674L. Used in heat pump applications.
Fig. 234. Schematic and hookup of T874G with Q674B. Used in heat pump applications.
FAN
SYSTEM
SWITCH
COOL
HEAT
H1
ANTICIPATOR
H1
FALL
M3952
AUTO
ON
FAN
SWITCH
R
G
L
Y
X
H3
E
W2
B
EM. HT.
LED (YELLOW)
1
2
3
5
4
6
SERVICE
LED (RED)
COMPRESSOR
LOW SPEED
FALL
AUX. HT.
O
Y1
COMPRESSOR
HIGH SPEED
EM. HT.
OFF
EM. HT.
W89
HEAT
PUMP
CONTROL
PANEL
COOL
CHANGEOVER
H2
ANTICIPATOR
H3
ANTICIPATOR
SERVICE LIGHT
EM. HT. LIGHT
T
OUTDOOR
RESET
8
9
11
10
12
FALL
C2
ANTICIPATOR
C1
ANTICIPATOR
RISE
H2
C1
C2
RESET
THERMOSTAT SUBBASE SYSTEM COMPONENTS
RISE
L2
1
OFF
H1
ANTICIPATOR
H1
FALL
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
M3961
CO
Y1
H2
RISE
W1
C1
ANTICIPATOR
C1
RISE
HEAT
1
4
6
8
9
10
FALL
AUX. HT. RELAY
COMPRESSOR
CONTACTOR
L1
(HOT)
R
FAN RELAY
O
AUTO
ON
FAN
SWITCH
AUX. HEAT
LED (RED)
C
G
H2
ANTICIPATOR
2
COOL
CHANGEOVER
VALVE
COOL
THERMOSTAT SUBBASE SYSTEM COMPONENTS
SYSTEM
SWITCH