Honeywell T874 - Page 197

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
197 60-2485—8
Fig. 207. Schematic and hookup of T874J with Q674L. Used in heat pump applications.
Fig. 208. Schematic and hookup of T874D with Q674D. Used in standard applications.
H1
FALL
Y
G
R
E
L
W2
FAN RELAY
COMPRESSOR
CONTACTOR
OFF
COOL
SYSTEM
SWITCH
H1 ANTICIPATOR
C1 ANTICIPATOR
AUTO
ON
FAN SWITCH
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
M2985
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
COOL CHANGEOVER
VALVE
O.D.T.
4
6
8
9
10
H2
FALL
RISE
CO
L1
(HOT
)
L2
1
H2
ANTICIPATOR
SUPL. HT.
LED (RED)
O
H.C.R.1
H.C.R.1
H.C.R.2
H.C.R.2
H.C.R.3
C
2
3
5
11
12
C1
CO
SUPL. HT.
RISE
HEAT
H1
FALL
W1
W2
HEAT RELAY 1
H1 ANTICIPATOR
C1 ANTICIPATOR
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED
.
RC-RH REMOVABLE JUMPER WHEN SPECIFIED.
M298
6
THERMOSTAT
SUBBASE SYSTEM COMPONENTS
COMPRESSOR
CONTACTOR 2
COMPRESSOR
CONTACTOR 1
1
5
6
8
9
10
11
H2
FALL
C2 ANTICIPATOR
RISE
RISE
C1
C2
Y1
Y2
HEAT RELAY 2
L1
(HO
T)
L2
1
H2
ANTICIPATOR
L1
(HO
T)
L2
1
RC
RH
2
4
NO
FAN
SWITCH
NO
SYSTEM
SWITCH
2