Honeywell T874 - Page 167

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
167 60-2485—8
Fig. 158. Schematic and hookup of T874G with Q674F. Used in heat pump applications.
4
OFF
EM. HT.
SYSTEM
SWITCH
HEAT
AUTO
COOL
AUX. HT. LED (GREEN)
1
X
M5721
8
C1 ANTICIPATOR
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
1
CO
RISE
FALL
H2
6
9
C1
RISE
H2 ANTICIPATOR
10
FALL
H1
H1 ANTICIPATOR
1
2
AUTO
ON
FAN
SWITCH
EM. HT. LED
(RED)
W
2
L1
(HOT) L2
1
AUX. HT. RELAY
Y
COMPRESSOR CONTACTOR
2
B TERMINAL ON SELECT MODELS.
R
B
HEAT CHANGEOVER VALVE
G
FAN RELAY
E
EM. HT. RELAY
O
COOL CHANGEOVER VALVE
COMPRESSOR
FAILURE
2
L
SYSTEM COMPONENTSSUBBASETHERMOSTAT