4
TH
TR
MV
MV
GND
FP
RO1
RO2
HLO
HLI
PS
C
R
G
W
Y
EAC N
E33
HUM N
XFMR N
LINE N
CIR N
IGN N
IND N
IGN
IND
HUM
EAC
XFMR
LINE
PARK
PARK
HEAT
COOL
IGNITOR
Y
W
G
R
THERMOSTAT
GAS
VALVE
HIGH LIMIT
(N. C.)
AUX. HIGH
LIMIT (N. C.)
PRESSURE SWITCH (N. O.)
FLAME
SENSOR
PROBE
COMPRESSOR
CONTACTOR
ELECTRONIC
AIR CLEANER
HUMIDIFIER
INDUCER
CIRCU-
LATOR
BLOWER
50A65-843
24 VAC
120 VAC
24 VAC CLASS II
TRANSFORMER
HOT
(LINE)
NEUTRAL
(LINE)
TH
TR
Low Voltage (24 VAC)
Line Voltage (120 VAC)
LEGEND
N. C. = Normally closed switch
N. O. = Normally open switch
TYPICAL SYSTEM WIRING DIAGRAM
