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8
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Electronic Appliance Checkout
To light the burner, refer to the lighting instruc-
tions on Pages20 and 21. Ensure the igniter
lights the pilot. The pilot fl ame should engulf
the fl ame sensor as shown in Figure 9.
With proper care and maintenance, your appli-
ance will provide many years of enjoyment. If
you should experience any problem, fi rst refer
to the trouble shooting guide in this manual.
If problem persists, contact your Lennox
distributor.
SIT Millivolt Appliance Checkout
The pilot fl ame should be steady, not lifting
or fl oating. Flame should be blue in color with
traces of orange at the outer edge.
The top 3/8" (10 mm) at the pilot generator
(thermopile) and the top 1/8" min (tip) of the
quick drop out thermocouple should be engulfed
in the pilot fl ame. The fl ame should project 1"
(25 mm) beyond the hood at all three ports
(Figure 8).
To light the burner, refer to the lighting instruc-
tions on Pages 18 and 19.
Figure 9
Burner Adjustments
Note - The air shutter for the burner primary
air opening is factory-set. Do not adjust the
factory-set position. The factory-set position
is shown in Figure 7.
Figure 7
Burner Air Shutter Adjustment
3/8" to 1/2"
(9 -13 mm)
Ground
Electrode
Flame Rod
Hot Surface
Igniter
Proper Flame
Adjustment
Pilot
Nozzels
ELECTRONIC PILOT ASSEMBLY
Proper Pilot Flame Appearance
Figure 8
Thermocouple
Thermopile
Pilot
Nozzels
SIT MILLIVOLT PILOT ASSEMBLY
3/8" Min.
(9 mm)
Igniter Rod
Hood
Proper Pilot Flame Appearance
Main Burner Factory Air Shutter
Opening Setting - Inches (millimeter)
Model Natural
Gas
Propane
Gas
MPB-3328 Fully Closed
3/16"
(4.76 mm)
MPB-3530 Fully Closed
3/16"
(4.76 mm)
MPB-4035 Fully Closed
3/16"
(4.76 mm)
MPB-4540 Fully Closed
3/16"
(4.76 mm)
Air Shutter
Venturi
Setscrew - Factory Located in the
Natural Gas Position; Relocate Set
Screw for LP/Propane Gas in the
Alternate Position. See Table for
Air Shutter Openings for these
Setscrew Locations.