Millivolt Appliance Checkout; Electronic Appliance Checkout; Warranty - Lennox MPB35ST-NM-B Care And Operation Instructions Manual

Burner Air Shutter Adjustment Procedure
WARNING
• Air shutter adjustment should
only be performed by a quali-
fied professional service
technician.
• Ensure front glass panel are
in place and sealed during
adjustment.
CAUTION
• Soot will be produced if the
air shutter is closed too much.
Any damage due to carboning
resulting from improperly
setting the air shutter is not
covered under the warranty.
• The air shutter door and nearby
appliance surfaces are hot.
Exercise caution to avoid
injury while adjusting flame
appearance.
1. Locate adjustment rod and adjust air shutter
to the standard setting as shown in Figure
16 (adjustment rod is located in the lower
control area). NOTE: Rotating the adjustment
rod counterclockwise decreases air and
clockwise increases air.
2. Light appliance (follow lighting procedure on
lighting label in control compartment or see
care and operation instructions manual).
3. Allow the burner to operate for at least 15 min-
utes while observing the flame continuously
to ensure that the proper flame appearance
has been achieved (see Figure 15). If the
following conditions are present, adjust
accordingly.
• If flame appears weak or sooty, adjust
the air shutter, incrementally, to a more
open position until the proper flame
appearance is achieved.
• If flame stays lowered blue, adjust the
air shutter, incrementally, to a more
closed position until the proper flame
appearance is achieved.
4. Leave the control knob (off/pilot/on) in the
ON position and the burner OFF/ON switch
OFF (and remote switches, if applicable).
5. When satisfied that the burner flame appear-
ance is normal, close the lower control
compartment door.
16
Main Burner Factory Air Shutter
Opening Setting - All Models
Model Natural
Gas
1/8"
MPB35ST
3.2mm
Ref. Air shutter Patent:
U.S. Pat. 5,553,603
Adjustment Rod Positions
(when viewed from above)
Figure 16

Millivolt Appliance Checkout

The pilot flame should be steady, not lifting
or floating. 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 flame. The flame should project 1"
(25 mm) beyond the hood at all three ports.
See Figure 17.
To light the burner, refer to the lighting instruc-
tions on Page 22.
Proper Pilot Flame
Hood
Appearance
Thermocouple
Pilot
Nozzels
Thermopile
Figure 17
- Millivolt Pilot Assembly
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Decrease Shutter Opening
In This Direction
Propane
Gas
1/4"
6.4mm
Air Shutter
Adjusting
Rod

Electronic Appliance Checkout

To light the burner, refer to the lighting instruc-
tions on Page 24. Ensure the igniter lights the
pilot. The pilot flame should engulf the flame
sensor as shown in Figure 18.
Proper Pilot Flame Appearance
Proper Flame
Adjustment
Pilot
Nozzels
Igniter Rod
3/8" Min.
(9 mm)
Figure 18
Note - Burners are
omitted in this
view for clarity.
Orifice
Increase Shutter Opening
In This Direction
3/8" to 1/2"
(9 -13 mm)
Ground
Electrode
Flame Rod
Hot Surface
Igniter
- Electronic Pilot Assembly