Thermostat User Manual

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8 218
Fig. 239. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
Fig. 240. Schematic and hookup of T874A with Q674W. Used in standard applications.
L1
(HOT
)
L2
1
1
2
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
FAN SWITCH
AUTO
ON
SYSTEM
SWITCH
HEAT
OFF
COOL
2
3
5
11
R
O
X2
T
G
B
W
Y
M7744
THERMOSTAT SUBBASE SYSTEM COMPONENTS
EM. HT.
H1
H2
FALL
FALL
C1
H1
ANTICIPATOR
RESET
U
F
FAN RELAY
AUX. HT.
RELAY
OUTDOOR
THERMOSTAT
COOL
CHANGEOVER
VALVE
COMPRESSOR
CONTACTOR
OUTDOOR
SENSOR
COMPRESSOR
MONITOR
1
4
6
AUX. HT.
LED (GREEN)
EM. HT.
LED (RED)
FIELD REMOVABLE JUMPER.
L1
(HOT)
L2
1
1
2
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
FAN CONTINUOUS IN ON POSITION.
SYSTEM
OFF
ON
FAN
MED
MED
HI
HI
8
10
R
G2
G1
W1
B
Y1
M7745
THERMOSTAT SUBBASE SYSTEM COMPONENTS
LO
LO
H1
FALL
C1
RISE
C1
ANTICIPATOR
H1
ANTICIPATOR
HEAT
RELAY
K1 RELAY
K2 RELAY
COMPRESSOR
CONTACTOR
1
4
9
B RELAY
L2
L1
K1 K
1
K2 K2 K
2
3 SPEED FAN SCHEMATIC