Honeywell T874G Installation Instructions Manual page 5

Fig. 7—Internal schematic and typical wiring diagram for Y594G1419 (T874G1642/Q674F1444),
Y594G1476 (T874G1741/Q674F1477) and Y594G1534 (T874G1824/Q674F1477 sold only in Australia); auto
changeover in heating and cooling; fixed anticipation. CHECK LED has isolated terminals. Factory-
installed W1-Y1 jumper is equivalent to Y terminal.
THERMOSTAT
CHANGEOVER
(HEAT)
FALL
H1
ANTICIPATOR
FALL
H2
H2 ANTICIPATOR
H1
FALL
CHANGEOVER
(COOL)
RISE
C1
ANTICIPATOR
C1
RISE
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
2
W1 - Y1 JUMPER IS Y TERMINAL; REMOVE JUMPER WHEN W1 RELAY IS USED.
FAN
1
SWITCH
AUTO
2
ON
3
4
5
SYSTEM
6
SWITCH
8
OFF
EM. HT.
9
HEAT
AUTO
10
COOL
11
SUBBASE
AUX.
HT. LED
(GREEN)
EM. HT.
LED (RED)
5
SYSTEM COMPONENTS
W3 RELAY
W3
FAN RELAY
G
R
AUX. HEAT
RELAY
W2
EM. HT.
RELAY
E
COMPRESSOR
FAULT
X1
CHECK
LED (RED)
X2
X
COOL CHANGEOVER
RELAY
O
B
HEAT CHANGEOVER
W1 RELAY
RELAY
W1
2 COMPRESSOR
CONTACTOR
Y1
1
L2
L1
(HOT)
M1230A
69-0435—10