Honeywell T874 - Schematic and Hookup of T874 D with Q674 L. Used in Heat Pump Applications

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
129 60-2485—8
Fig. 107. Schematic and hookup of T874D with Q674L. Used in heat pump applications.
Fig. 108. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
C2
RISE
C1
RISE
H2
FALL
H1
FALL
L1
(HOT)
L2
1
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
H1
ANTICIPATOR
C2 ANTICIPATOR
H2
ANTICIPATOR
C1 ANTICIPATOR
SYSTEM
SWITCH
FAN
SWITCH
AUTO
ON
OFF
HEAT
EM. HT.
COOL
M4727
Y
R
C
L
E
Y1
G
O
11
10
8
5
4
3
2
EM. HT.
LED (RED)
COMPRESSOR
CONTACTOR 1
COMP.
FAILURE
EM. HT.
RELAY CONTACT
EM. HT. RELAY
COMPRESSOR
CONTACTOR 2
OUTDOOR
THERMSTAT
SUPPL. HT.
RELAY
FAN RELAY
COOL CHANGEOVER
VALVE
H2
FALL
H1
FALL
C1
L1
(HOT
)
L2
1
1
POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
H1/C1
ANTICIPATOR
H2
ANTICIPATOR
FAN
SWITCH
AUTO
ON
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
AUX. HT. RELAY
FAN RELAY
COOL CHANGEOVER
VALVE
COMPRESSOR
CONTACTOR
M472
5
2
3
4
5
6
R
G
W
B
X
O
Y
AUX. HT.
LED (YELLOW)
EM. HT.
LED (RED)