T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
159 60-24858
Fig. 147. Schematic and hookup of T874G with Q674F. Used in heat pump applications. Fig. 148. Schematic and hookup of T874G with Q674F. Used in heat pump applications.
H1
FALL
1
G
A
X
W2
R
AUTO
COOL
SYSTEM
SWITCH
H1
ANTICIPATOR
AUTO
ON
FAN
SWITCH
1POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
CONNECT TO Y OR W TERMINAL WITH FACTORY INSTALLED JUMPER. M7024
THERMOSTAT SUBBASE SYSTEM COMPONENTS
4
8
9
10
H2
ANTICIPATOR
O
L
2
3
6
EM. HT.
HEAT
OFF
Y
H2
FALL
CO
RISE
C1
ANTICIPATOR
RISE C1
L1
(HOT)
L2
1
2
S
W3
E
T
MODE SIGNAL
COOL
CHANGEOVER
VALVE
COMPRESSOR
CONTACTOR
EM. HT. RELAY
HEAT RELAY 1 HEAT RELAY 2
FAN RELAY
MODE SIGNAL
5
AUX. HT.
LED (GRN)
EM. HT.
LED (YEL)
SERVICE
LED (RED)
2
2
3JUMPER FACTORY INSTALLED.
3
OFF
COOL
DEFROST
RELAY
FAN
SWITCH
ON
SYSTEM
SWITCH
1POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. M8382
AUX. HT. RELAY
EM. HT. RELAY
4
EM. HT.
LED
(RED)
EM. HT.
HEAT
AUTO
COOL CHANGEOVER
VALVE
BLOWER SPEED
RELAY
DEFROST
RELAY
BLOWER RELAY
COOL
CONTRACTOR
LOCKOUT
THERMOSTAT
AUTO
E
H1 ANTICIPATOR
H2 ANTICIPATOR
C1
ANTICIPATOR
C1 RISE
RISE
6
O
8
10
R
CO
FALL
H1
FALL
H2 W2
L1
(HOT)
L2 1
G
1
Y
C
THERMOSTAT SUBBASE SYSTEM COMPONENTS
9
2