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6. Flame Sensor
A flame sensor is located on the left side of the burner sup-
port. See figure 10. The sensor is mounted on the flame
rollout plate and the tip protrudes into the flame envelope
of the left−most burner. The sensor can be removed for ser-
vice without removing any part of the burners. During op-
eration, flame is sensed by current passed through the
flame and sensing electrode. The SureLight control allows
the gas valve to remain open as long as flame signal is
sensed. See table 16 for flame signal.
7. Ignitor
The SureLight ignitor is made of durable silicon nitride. Ig-
nitor longevity is enhanced by controlling voltage to the ig-
nitor. The board finds the lowest ignitor temperature which
will successfully light the burner, thus increasing the life of
the ignitor. Due to this feature of the board, voltage cannot
be measured so ignitor must be ohmed. Ohm value should
be 10.9 to 19.7. See figure 12 for ignitor location.
NOTE − The G50UH(X) furnace contains electronic
components that are polarity sensitive. Make sure that
the furnace is wired correctly and is properly
grounded.
FIGURE 10
5/16"
8. Blower Motors and Capacitors
All G50UH(X) units use direct drive blower motors. All mo-
tors are 120V permanent split capacitor motors to ensure
maximum efficiency. Ratings for capacitors will be on motor
nameplate.
NOTE − The shaft on 1 HP motors have 2 flat sides and
are matched with blower wheels with 2 set screws.
FIGURE 11
SUPPLY AIR BLOWER
AND SECONDARY LIMIT (S)
SECONDARY
LIMIT (S)
CAPACITOR
MOTOR/BLOWER
ASSEMBLY
To Remove Blower From Unit: Disconnect Power, Remove Control
Box, Remove Bolts and Unplug Motor Wires From Control Board.
Then Slide Out Front of Unit.
FIGURE 12
5/16"
13/32’
5/8"
SureLight Ignitor Location
BURNERS TOP VIEW
BURNERS FRONT VIEW
MEASUREMENT IS TO I.D.
OF RETENTION RING
IGNITOR
BRACKET
