Lennox G61MPV Service Manual page 45

C−Heating Components
6. Ignitor
The SureLight ignitor is made of durable silicon nitride. Ig-
nitor longevity is enhanced by controlling voltage to the ig-
nitor. Board 49M59 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. Board
100870 provides a regulated 95 volts to the ignitor for con-
sistent ignition and long ignitor life. Ohm value for ignitors
with SureLight board 49M59 should be 10.9 to 19.7. Ohm
value for ignitors with board 100870 should be 25 to 47. Ig-
nitors not interchangeable between boards. See figure 14
and 15 (make note of control board used) for ignitor loca-
tion.
MEASUREMENT IS TO
5/8
I.D. OF RETENTION
RING
"
13/32'
IGNITOR
BURNERS FRONT VIEW
MEASUREMENT IS TO
5/8
I.D. OF RETENTION
RING
"
7/32'
IGNITOR
BURNERS FRONT VIEW
SureLight Board 49M59 Ignitor Location
BRACKET
FIGURE 14
SureLight Board 100870 Ignitor Location
BRACKET
FIGURE 15
Page 45
NOTE − The G61MPV(X) furnace contains electronic
components that are polarity sensitive. Make sure that
the furnace is wired correctly and is properly grounded.
7. Flame Sensor
A flame sensor is located on the left side of the burner sup-
port. See figure 16 and 17 (make note of control board
used). 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 service without re-
moving any part of the burners. During operation, flame is
sensed by current passed through the flame and sensing
electrode. The SureLight control allows the gas valve to re-
main open as long as flame signal is sensed.
5/16"
BURNERS TOP VIEW
21/64"
BURNERS TOP VIEW