69-0435—10 4Fig. 5—Internal schematic and typical wiring diagram for Y594G1252 (T874G1246/Q674F1212); autochangeover in cooling.
H2
FALL
L1
(HOT)
L2 1
R
W3
W2
X
L
G
O
E
Y
RTD1 OTD1
EHR1
ODT2
EHR2
RTD2
RTD3
RTD1
SYSTEM
MONITOR
FAN
RELAY
RD
COOL
CHANGEOVER VALVE
EM. HEAT
RELAY
LACO
COMPRESSOR
CONTACTOR CHP
2
3
4
5
6
8
9
10
H1 FALL
H1 ANTICIPATOR
H2
ANTICIPATOR
CHANGEOVER
RISE
C1
RISE
C1
ANTICIPATOR
OFF
COOL
AUTO
HEAT
EM. HT.
SYSTEM
SWITCH
AUTO
ON
FAN
SWITCH
AUX. HEAT
LED (GRN)
EM. HEAT
LED (RED)
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
W3 TERMINAL ON SELECT MODELS.
1
2
2
M1589
THERMOSTAT SUBBASE SYSTEM COMPONENTS
Fig. 6—Internal schematic and typical wiring diagram for T874G1246/Q674F1410. Separate W1 and Y1terminals can be jumpered together to form Y terminal.
H1
FALL
RISE
CO
L1
(HOT)
L2
1
C1
RISE
1
2
3
3
2
POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD PROTECTION AS REQUIRED.
ON SOME MODELS, Y TERMINAL MAY BE LABELED Y1.
EMERGENCY HEAT RUNS CONTINUOUSLY WHEN SWITCH IN IN EM. HT. POSITION.
C1 ANTICIPATOR
H1 ANTICIPATOR FAN SWITCH
AUTO
ON
SYSTEM
SWITCH
AUTO
HEAT
OFF
COOL
2
4
8
9
10
W2
X
L
B
R
G
Y
AUX. HEAT RELAY
FAN RELAY
EM. HT.
RELAY
B RELAY
M5987A
THERMOSTAT SUBBASE SYSTEM COMPONENTS
COMPRESSOR
CONTACTOR
EM. HT.
EM. HT.
LED (RED)
AUX. HEAT
LED (GREEN)
H2
FALL
H2
ANTICIPATOR
3
5
W3
W1 W3 RELAY W1 RELAY
COOL
CHANGEOVER
VALVE
COMPRESSOR
FAULT
E
O
6