Honeywell Q674L User Manual
Page 4
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)
L2
1
G
W
U
B
F
R
T
X2
O
Y
FAN RELAY
AUX. HEATER
RELAY
COMPRESSOR
MONITOR
OUTDOOR
THERMOSTAT
OUTDOOR
THERMISTOR
COOL
CHANGEOVER
VALVE
COMPRESSOR
RELAY
AUX. HT.
LED (GREEN)
EM. HT.
LED (RED)
1
2
3
4
5
6
11
FAN
SWITCH
AUTO
ON
EM. HT.
HEAT
OFF
COOL
SYSTEM
SWITCH
H2
FALL
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
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
FAN RELAY
COMPRESSOR
CONTACTOR
COOL CHANGEOVER
VALVE
EM. HT.
RELAY
RTD 1
AUX. HT.
LED
(GREEN)
EM. HT.
LED (RED)
FAN SWITCH
ON
AUTO
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
H2
FALL
H1
FALL
C1
2
3
4
5
6
H1/C1
ANTICIPATOR
H2
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).