T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
137 60-24858
Fig. 116. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
H2
FALL
H1
FALL
C1
YR
COM
G
W
OEH
O
G
Y
A
H
W2
R
B
X
E
L1
(HOT)
L2
1
COMPRESSOR
CONTACTOR
AUX. HT. RELAY
EM. HT. RELAY
EM. HT.
LED (RED)
EM. HT.
HEAT
OFF
COOL
COMP. FAULT
LED (YELLOW)
SYSTEM
SWITCH
FAN
SWITCH
AUTO
ON
1 POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
OPTIONAL FIELD WIRE JUMPER TO CYCLE
AUXILIARY HEAT RELAY WITH H1 INSTEAD
OF H2 (FASTER RESPONSE).
2ELEC.
HT. RELAY
M2857
H1/C1
ANTICIPATOR
H2 ANTICIPATOR
2
R8233B
THERMOSTAT SYSTEM COMPONENTS
SUBBASE
2
5
6
4
3