Honeywell Q674L User Manual
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69-0392—9
4
T874R THERMOSTATS AND Q674L SUBBASES
Fig. 5. Internal schematic and typical wiring diagram for Y594R1763 (T874R1954/Q674L1827). Replaces
GE AY28X078, AY28X139; Trane Baystat 139, Baystat 239 and Baystat 240;
and Honeywell Y594R1136 Thermostats.
H1
FALL
C1
L1
(HOT)
(HOT)
L2
1
G
W
U
B
F
R
T
X2
O
Y
FAN RELAY
AUX. HEATER
RELAY
RELAY
COMPRESSOR
MONITOR
MONITOR
OUTDOOR
THERMOSTAT
THERMOSTAT
OUTDOOR
THERMISTOR
THERMISTOR
COOL
CHANGEOVER
VALVE
CHANGEOVER
VALVE
COMPRESSOR
RELAY
RELAY
AUX. HT.
LED (GREEN)
LED (GREEN)
EM. HT.
LED (RED)
LED (RED)
1
2
3
4
5
6
11
FAN
SWITCH
SWITCH
AUTO
ON
EM. HT.
HEAT
OFF
COOL
SYSTEM
SWITCH
SWITCH
H2
FALL
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
OVERLOAD PROTECTION AS REQUIRED.
FIELD REMOVABLE JUMPER.
1
2
2
M2970
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
M5072A
(HOT) L1
L2
1
LACO
CHP
Y
B
E
O
G
L
X
W2
W3
R
ODT 1
RTD 1
EHR 1
RTD 2
ODT 2
EHR 2
RTD 3
RD
SYSTEM
MONITOR
MONITOR
FAN RELAY
COMPRESSOR
CONTACTOR
CONTACTOR
COOL CHANGEOVER
VALVE
VALVE
EM. HT.
RELAY
RELAY
RTD 1
AUX. HT.
LED
(GREEN)
LED
(GREEN)
EM. HT.
LED (RED)
LED (RED)
FAN SWITCH
ON
AUTO
SYSTEM
SWITCH
SWITCH
EM. HT.
HEAT
OFF
COOL
H2
FALL
H1
FALL
C1
2
3
4
5
6
H1/C1
ANTICIPATOR
ANTICIPATOR
H2
ANTICIPATOR
ANTICIPATOR
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
AUXILIARY HEAT LED AVAILABLE ON SOME MODELS.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
2
2
Fig. 6. Internal schematic and typical wiring diagram for Y594R1243 (T874R1152/Q674L1207).