Filter
Top Products
T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
157 60-2485—8
Fig. 143. Schematic and hookup of T874G with Q674B. Used in heat pump applications.
Fig. 144. Schematic and hookup of T874J with Q674J. Used in heat pump applications.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
M8378
H1
FALL
1
H1 ANTICIPATOR
2
FAN
SWITCH
AUTO
ON
4
R
COMPRESSOR
CONTACTOR
FAN RELAY
H2
FALL
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
CO
RISE
H2
ANTICIPATOR
8
L1
(HOT)
1
10
9
C1
RISE
G
AUX. HT. RELAY
L2
W1
C
AUX. HT. LED
(RED)
6
SYSTEM
SWITCH
OFF
AUTO
C1
ANTICIPATOR
O
Y1
COOL
CHANGEOVER VALVE
H1
FALL
C1
RISE
CO
H2
FALL
CO
RISE
L1
(HOT)
L2
1
THERMOSTAT SUBBASE
SYSTEM COMPONENTS
COMPRESSOR CONTACTOR
FAN RELAY
HEAT RELAY 1
OUTDOOR
THERMOSTAT
HEAT RELAY
CONTACT 1
HEAT RELAY 2
HEAT RELAY
CONTACT 2
HEAT RELAY 3
"X" RELAY
"P" RELAY
COOL CHANGEOVER
VALVE
SYSTEM
SWITCH
SUPL. HT.
ON
OFF
FAN
SWITCH
AUTO
ON
H1 ANTICIPATOR
H2 ANTICIPATOR
C1 ANTICIPATOR
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
1
3
4
5
6
8
9
10
11
O
P
X
E
C
L
G
Y
R
2
W2
SUPP. HT.
LED (RED)
M5956
12