Thermostat User Manual

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8 148
Fig. 130. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
H2
FALL
H1
FALL
C1
L1
(HOT)
L2
1
2
2
1
POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
FACTORY-INSTALLED JUMPER.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
H1/C1
ANTICIPATOR
H2 ANTICIPATOR
SYSTEM
SWITCH
FAN
SWITCH
AUTO
ON
OFF
HEAT
EM. HT.
COOL
FAN RELAY
EM. HT. RELAY
COOL
CHANGEOVER VALVE
COMPRESSOR
CONTACTOR
M1628
A
COMPRESSOR
FAILURE
C815A OUTDOOR
THERMISTOR
SYSTEM
LED (GREEN)
CHECK
LED
(RED)
AUX. HT.
LED
(YELLOW)
2
3
4
5
6
11
12
RESET
Y
T
C
X
E
W1
R
G
O