Honeywell T874G Installation Instructions Manual page 7

Fig. 10—Internal schematic and typical wiring diagram for Y594G1567 (T874G1865/Q674J1209) and
Y594G1575 (T874G1873/Q674J1225); auto changeover in cooling. Exact replacement for York model
nos. 2TH11702424 and 6TH11702424.
THERMOSTAT
FALL
H1
H1 ANTICIPATOR
H2 ANTICIPATOR
FALL
H2
RISE
CO
C1 ANTICIPATOR
RISE
C1
Fig. 11—Internal schematic and typical wiring diagram for Y594G1633 (T874G1972/Q674F1584); auto
changeover in heating and cooling.
THERMOSTAT
FALL
H1 ANTICIPATOR
H1
H2
ANTICIPATOR
H2 FALL
RISE
C1
C1 ANTICIPATOR
RISE
CO
2
3
4
5
6
8
9
10
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
1
FAN SWITCH
AUTO
2
ON
4
6
SYSTEM
SWITCH
EM. HT.
HEAT
AUTO
COOL
8
9
10
11
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
1
OVERLOAD PROTECTION AS REQUIRED.
12
SUBBASE
FAN
SWITCH
AUTO
ON
SYSTEM
SWITCH
EM. HT.
AUTO
OFF
SUBBASE
OFF
7
SYSTEM COMPONENTS
O
COOL CHANGEOVER VALVE
G
FAN RELAY
R
W
AUX. HEAT RELAY
X
EM. HEAT RELAY
EM. HEAT
LED (RED)
B
COMPRESSOR
CONTACTOR
Y
SYSTEM COMPONENTS
O
COOL CHANGEOVER
VALVE
G
B RELAY
FAN RELAY
B
R
E
EM. HT. RELAY
L
EM. HT.
LED (RED)
X
AUX. HEAT
LED (GREEN)
AUX. HEAT RELAY
W2
Y
COMPRESSOR
CONTACTOR
L1
(HOT)
L2
1
M5723
L1
(HOT)
L2
1
M5986
69-0435—10