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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
109 60-2485—8
Fig. 69. Schematic and hookup of T874V with Q674R. Used in fan coil applications.
Fig. 70. Schematic and hookup of T874C with Q674S. Used in heat pump applications.
C1
RISE
L1
(HOT)
L2
1
M107A
FAN SWITCH
LO
AUTO
HI
CONT.
SYSTEM SWITCH
OFF
COOL
C1 ANTICIPATOR
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
COOL RELAY
FAN RELAY
Z RELAY
8
9
10
Y
R
G
Z
1
THERMOSTAT
SUBBASE SYSTEM COMPONENTS
H1
FALL
L1
(HOT)
L2
1
H2
FALL
H1
FALL
1
4
6
8
9
S
W2
R
Y
NO FAN
SWITCH
SYSTEM
SWITCH
HEAT
COOL
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
SERVICE
LED (RED)
AUX. HT. RELAY
COMPRESSOR
CONTACTOR
M1402A
POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD PROTECTION AS REQUIRED.
1
COMPRESSOR
FAULT