Honeywell T874 - Page 185

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
185 60-2485—8
Fig. 183. Schematic and hookup of T874G with Q674J. Used in heat pump applications.
Fig. 184. Schematic and hookup of T874A,F with Q674G. Used in standard applications.
L1
(HOT)
L
2
1
FAN RELAY
SYSTEM
SWITCH
OFF
EM. HT.
H1
ANTICIPATOR
H1
FALL
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
M3950
AUTO
ON
FAN
SWITCH
R
G
CO
W
Y
X
H2
RISE
E
O
C1
ANTICIPATOR
C1
RISE
L1
EM. HT.
LED (RED)
ON
1
2
4
6
8
9
10
AUX. HT.
LED (GREEN)
COMPRESSOR
CONTACTOR
COMPRESSOR
FAILURE
FALL
COOL CHANGEOVER
VALVE
2BH
O. D. S.
1BH SH
1BH
H2
ANTICIPATOR
THERMOSTAT SUBBASE SYSTEM COMPONENTS
L1
(HOT
)
L2
1
SYSTEM
SWITCH
OFF
H1
ANTICIPATOR
H1
FALL
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
M3953
RH
C1
Y1
H2
RISE
W1
C1
ANTICIPATOR
C2
RISE
AUTO
1
4
6
8
9
10
COMPRESSOR
CONTACTOR 2
FALL
HEAT RELAY 1
RC
Y2
11
C2
ANTICIPATOR
W2
HEAT RELAY 2
COMPRESSOR
CONTACTOR 1
L1
(HOT
)
L2
1
H2
ANTICIPATOR
THERMOSTAT SUBBASE SYSTEM COMPONENTS
NO
FAN
SWITCH