Honeywell T874 Product Data page 155

THERMOSTAT
1
FALL
H1 ANTICIPATOR
H1
2
H2
H2 ANTICIPATOR
FALL
3
H3 ANTICIPATOR
4
H3
FALL
5
6
RESET
RISE
8
C1
9
C1 ANTICIPATOR
10
C2 ANTICIPATOR
RISE
11
C2
12
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
2 CONNECT CHANGEOVER RELAY TO 'O' TERMINAL FOR CHANGEOVER IN COOLING OR TO 'B' TERMINAL FOR CHANGEOVER IN HEATING.
Fig. 140. Schematic and hookup of T874W with Q674L. Used in heat pump applications.
T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
SUBBASE
FAN SWITCH AUX. HT.
LED
(GREEN)
AUTO
ON
EM. HT.
LED (RED)
CHECK LED
(RED)
SYSTEM
SWITCH
EM.HT.
HEAT
OFF
COOL
155
SYSTEM COMPONENTS
T
C815A OD THERMISTOR
W3
AUX. HT. RELAY
U
G
R
E
EM. HT. RELAY
COMPRESSOR
MONITOR
L
X
B
HEAT CHANGEOVER
2
RELAY
COOL CHANGEOVER
RELAY
O
COMPRESSOR
CONTACTOR 1
Y1
COMPRESSOR
CONTACTOR 2
Y2
L1
(HOT)
L2
1
FAN RELAY
M156A
60-2485—8