Honeywell T874 - Page 133

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
133 60-2485—8
Fig. 112. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
OFF
COOL
COMPRESSOR
FAILURE
FAN
SWITCH
ON
SYSTEM
SWITCH
1
POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
M8383
AUX. HT. RELAY
4
EM. HT. LED
(RED)
AUX. HT. LED
(GREEN)
EM. HT.
HEAT
COOL CHANGEOVER
VALVE
FAN RELAY
EM. HT. RELAY
AUTO
Y
C1
H1
FALL
H1/C1
ANTICIPATOR
H2
ANTICIPATOR
H2
FALL
COMPRESSOR
CONTACTOR
6
O
5
R
W2
L1
(HOT)
L2
1
G
2
3
E
X
L1
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS