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TH
TR
MV
MV
GND
FP
HLO
HLI
PS
C
R
G
W
Y
EAC N
HUM N
XFMR N
LINE N
CIR N
IGN
IND
IGN N
IND N
HUM
EAC
XFMR
LINE
PARK
PARK
HEAT
COOL
IGNITOR
Y
W
G
R
THERMOSTAT
GAS
VALVE
HIGH LIMIT
(N. C.)
ROLLOUT
(N. C.)
AUX. HIGH
LIMIT (N. C.)
PRESSURE SWITCH (N. O.)
FLAME
SENSOR
PROBE
COMPRESSOR
CONTACTOR
ELECTRONIC
AIR CLEANER
HUMIDIFIER
INDUCER
CIRCULATOR
BLOWER
50A55
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
RO1
RO2
TYPICAL SYSTEM WIRING DIAGRAM
TWIN* TWIN*
50A55-843
in other
furnace(s)
—
TWINNING
APPLICATIONS
ONLY
50A55-843
WIRING AND
CONFIGURATION
Flame Current Requirements:
Minimum current to insure flame detection.............1 µa DC➀
Maximum current for non-detection.....................0.1 µa DC➀
Maximum allowable leakage resistance............. 100 M ohms
Flame establishing time......................0.8 seconds maximum
Flame failure response time................2.0 seconds maximum
➀ Measured with a DC microammeter in the flame probe lead
50A55-843
183
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