Honeywell T874 Product Data page 222

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
THERMOSTAT
FALL
H1 ANTICIPATOR
H1
H2
H2 ANTICIPATOR
FALL
H3 ANTICIPATOR
H3
FALL
RESET
RISE
C1
C1 ANTICIPATOR
C2 ANTICIPATOR
RISE
C2
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. 247. Schematic and hookup of T874W with Q674L. Used in heat pump applications.
60-2485—8
SUBBASE
1
2
3
FAN SWITCH
AUTO
4
ON
5
6
8 SYSTEM
SWITCH
EM.HT.
9
HEAT
OFF
10
COOL
11
12
222
SYSTEM COMPONENTS
T
C815A OUTDOOR
THERMISTOR
W3
AUX. HT. RELAY
AUX. HEAT
LED (GREEN)
G
R
EM. HEAT
LED (RED)
E
EM. HT. RELAY
X1
CHECK LED
(YELLOW)
C
CHANGEOVER
RELAY (HEAT)
B
O
X2
COMPRESSOR
CONTACTOR 1
Y1
Y2
FAN RELAY
L1
(HOT)
L2
1
2
CHANGEOVER
RELAY (COOL)
COMPRESSOR
CONTACTOR 2
M6999