69-0268—11 8

T874G,R MULTISTAGE HEAT PUMP THERMOSTATS AND Q674F,J,L SUBBASES
M5072A
(HOT) L1 L2
1
LACO CHP
Y
B
E
O
G
L
X
W2
W3
RODT 1
RTD 1 EHR 1 RTD 2
ODT 2
EHR 2 RTD 3
RD
SYSTEM
MONITOR
FAN RELAY
COMPRESSOR
CONTACTOR
COOL CHANGEOVER
VALVE
EM. HT.
RELAY
RTD 1
AUX. HT.
LED
(GREEN)
EM. HT.
LED (RED)
FAN SWITCH
ON
AUTO
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
H2
FALL
H1
FALL
C1
2
3
4
5
6
H1/C1
ANTICIPATOR
H2
ANTICIPATOR
1POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
AUXILIARY HEAT LED AVAILABLE ON SOME MODELS.
THERMOSTAT SUBBASE SYSTEM COMPONENTS
2
2

Fig. 9. Internal schematic and typical hookup for T874R/Q674L in heat pump system. Includes EM. HT. and AUX.

HT. LEDs and W3 terminal for additional heat stage.