Honeywell T874 Product Data page 178

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
THERMOSTAT
FALL
H1
H1 ANTICIPATOR
H2 ANTICIPATOR
FALL
H2
CO
RISE
C1 ANTICIPATOR
C1
RISE
CO
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
2 EXTERNAL JUMPER SUPPLIED BY HONEYWELL.
Fig. 171. Schematic and hookup of T874J with Q674J. Used in heat pump applications.
THERMOSTAT
FALL
H1
RISE
C1 ANTICIPATOR
CO
C1
RISE
Fig. 172. Schematic and hookup of T874H with Q674B. Used in heat pump applications.
60-2485—8
2
FAN
3
SWITCH
AUTO
4
ON
5
6
8
9
SYSTEM
SWITCH
EM. HT.
10
AUTO
OFF
11
12
FAN
2
SWITCH
H1 ANTICIPATOR
AUTO
3
4
8
SYSTEM
SWITCH
9
HEAT
10
OFF
COOL
11
12
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
SUBBASE
EM. HT. LED
(RED)
SUBBASE
ON
FAULT
LED
(RED)
CHECK
FILTER
LED (YELLOW)
178
SYSTEM COMPONENTS
L1
R
(HOT)
L2
Y
O.D.T.
COMPRESSOR
CONTACTOR
G
FAN RELAY
HCR1
W 1
HCR1
F
C
2
E
HCR2
X
"X" RELAY
"P" RELAY
P
O
COOL CHANGEOVER
VALVE
SYSTEM COMPONENTS
FAN RELAY
G
R
O
COOL
2
CHANGEOVER
VALVE
C
3
Y
COMPRESSOR
CONTACTOR
1
HCR2
HCR3
M5729
L1
(HOT)
L2
1
M1401