T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
217 60-2485—8
Fig. 237. Schematic and hookup of T874C with Q674B. Used in standard applications. Fig. 238. Schematic and hookup of T874C with Q674F. Used in heat pump applications.
H1
H2
FALL G
B
R
FAN RELAY
OFF
COOL
SYSTEM
SWITCH
H2 ANTICIPATOR
H1 ANTICIPATOR
C1 ANTICIPATOR
AUTO
ON
FAN SWITCH
1POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. M7716
THERMOSTAT SUBBASE SYSTEM COMPONENT
S
3
4
6
8
10
FALL
RISE
C1
L1
(HOT)
L2
1
2
1
Y
COMPRESSOR
CONTACTOR
W1
W2
HEAT 1
HEAT 2
HEAT
5LOW LED
(YELLOW)
HI LED
(GREEN)
H1
FALL
L1
(HOT
)
L2 1
1
2
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
FACTORY INSTALLED JUMPER BETWEEN TERMINALS W1 AND Y1.
H1
ANTICIPATOR FAN SWITCH
AUTO
ON
SYSTEM
SWITCH
OFF
COOL
2
4
6
X
O
C
W1
W2
B
R
G
Y1
COOL
CHANGEOVER
VALVE
FAN RELAY
AUX. HT.
RELAY
HEAT PUMP
RELAY
M7719
C1
ANTICIPATOR
B RELAY
THERMOSTAT SUBBASE SYSTEM COMPONENTS
COMPRESSOR
CONTACTOR
AUX. HT.
LED (RED)
H2
RISE
C1
FALL
H2
ANTICIPATOR
1
8
10
2 STAGE HT.
HT. PUMP
AUX. HT.
CHECK
LED (RED)