T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-24858192
Fig. 197. Schematic and hookup of T874R with Q674L. Used in heat pump applications. Fig. 198. Schematic and hookup of T874L with Q674E. Used in standard applications.
H1
FALL
C1
L1
(HOT)
L2
1
G
W
U
B
F
R
T
X2
O
Y
FAN RELAY
AUX. HEATER
RELAY
COMPRESSOR
MONITOR
OUTDOOR
THERMOSTAT
OUTDOOR
THERMISTOR
COOL
CHANGEOVER
VALVE
COMPRESSOR
RELAY
AUX. HT.
LED (GREEN)
EM. HT.
LED (RED)
1
2
3
4
5
6
11
FAN
SWITCH
AUTO
ON
EM. HT.
HEAT
OFF
COOL
SYSTEM
SWITCH
H2
FALL
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
FIELD REMOVABLE JUMPER.
1
2
2
M2970
THERMOSTAT SUBBASE SYSTEM COMPONENTS
H1
FALL
W1
Y1
W2
COMPRESSOR
CONTACTOR
HEAT
AUTO
COOL
SYSTEM
SWITCH
H1 ANTICIPATOR AUTO
ON
FAN
SWITCH
1POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
M2976
R
STAGE 2
HEAT RELAY
1
4
6
7
9
10
H2
FALL
C2 ANTICIPATOR
RISE C1
STAGE 1 HEAT RELAY
L1
(HOT)
L2
1
H2
ANTICIPATOR
G
FAN RELAY
3
8
OFF
THERMOSTAT SUBBASE SYSTEM COMPONENTS