T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
131 60-24858
Fig. 110. Schematic and hookup of T87C,R with Q674L. Used in heat pump applications.
L1
(HOT)
L2
1
F
EM. HT.
LED (YELLOW)
R
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
H1
ANTICIPATOR
1POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
M2854
VR
H1
FALL
E
AUTO
ON
FAN SWITCH
A
L
M
OUTDOOR
THERMOSTAT SUPL. ELEC.
HT. RELAY
X
COMPRESSOR
CONTACTOR
OVERLOAD
SWITCH
INTERNAL
THERMOSTAT
HI PRESSURE
SWITCH
FAN
RELAY
EM. HT. RELAY
CONTACT TIME DELAY
FAN RELAY
ELEC. HT. RELAY
H2
FALL
H2
ANTICIPATOR
C1
RISE
C1
ANTICIPATOR
REMOVE FACTORY INSTALLED V-VR JUMPER WHEN
CONNECTING A TWO TRANSFORMER SYSTEM.
2
2
SERVICE
S
Y
C815A OUTDOOR
THERMISTOR
COOL CHANGEOVER
VALVE
V
SERVICE
LED (RED)
3
RESET
REMOVE FACTORY-INSTALLED S-Y JUMPER TO DISABLE SERVICE LIGHT.
3
10
8
7
6
5
4
3
2
1
THERMOSTAT SUBBASE SYSTEM COMPONENTS