T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
141 60-2485—8
Fig. 121. Schematic and hookup of T874C with Q674L. Used in heat pump applications.
L1
(HOT)
L2 1
R
L
X
W2
G
O
E
B
Y
ODT1
EHR1
ODT2
EHR2
RTD2
RTD3
RTD1
COMPRESSOR
FAILURE
HEAT CHANGEOVER
VALVE
COMPRESSOR
CONTACTOR
LACO CHP
EM. HT.
RELAY
COOL CHANGEOVER
VALVE
FAN RELAY
RD
RTD1
H1
FALL
H2
FALL
C1
RISE
2
3
4
5
6
8
10
AUX. HT.
LED (GRN)
EM. HT.
LED (RED)
AUTO
ON
FAN
SWITCH
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
H2 ANTICIPATOR
H1 ANTICIPATOR
1POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED. M7012
C1
ANTICIPATOR
THERMOSTAT SUBBASE SYSTEM COMPONENTS