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NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
WARNINGS
• Air shutter adjustment should
only be performed by a quali-
fied professional service tech-
nician.
• Ensure front glass panel are
in place and sealed during
adjustment.
CAUTIONS
• 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.
Burner Air Shutter Adjustment Procedure
Adjustment Rod Positions
(when viewed from above)
Figure 35
Main Burner Factory Air Shutter
Opening Setting - All Models
Model Natural
Gas
Propane
Gas
MPB35ST
1/8”
3.2mm
1/4”
6.4mm
Air Shutter
Adjusting Rod
Increase Shutter Opening
In This Direction
Decrease Shutter Opening
In This Direction
Note - Burners are omitted in this view for clarity.
Orifice
Burner Air Shutter Adjustment Procedure
1. Locate adjustment rod and adjust air shutter
to the standard setting as shown in Figure
35 (adjustment rod is located in the lower
control area).
Note: Rotating the adjustment rod coun-
terclockwise 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 34).
Figure 34 - Burner Flame Appearance
Vermiculite
If the following conditions are present, adjust
accordingly.
• If ame appears weak or sooty, adjust the
air shutter, incrementally, to a more open
position until the proper flame appearance
is achieved.
• If ame 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 (& remote switches, if applicable).
5. When satisfied that the burner flame appear-
ance is normal, close the lower control
compartment door then proceed to finish
the installation.
Air Shutter Adjustment Guidelines:
Amount of
Primary Air
Flame
Color
Air Shutter
Adjustment
If air shutter is
closed too far
Flame will
be orange
Air shutter
gap should be
increased
If air shutter is
open too far
Flame will
be blue
Air shutter
gap should be
decreased
Step 10. BURNER ADJUSTMENTS
Flame Appearance and Sooting
Proper flame appearance is a flame which is
blue at the base and becomes yellowish-orange
in the body of the flame.
When the appliance is first lit, the entire flame
may be blue and will gradually turn yellowish-
orange during the first 15 minutes of operation.
After 15 minutes of operation, if the flame is
blue, or if the flame is orange with evidence of
sooting (black tip), the air shutter opening may
need to be adjusted.
If the air shutter opening is closed too far,
sooting may develop. Sooting is indicated by
black puffs developing at the tips of very long
orange flames. Sooting results in black deposits
forming on the logs, appliance inside surfaces
and on exterior surfaces adjacent to the vent
termination.
Sooting is caused by incomplete combustion
in the flames and lack of combustion air enter-
ing the air shutter opening. To achieve a warm
yellowish-orange flame with an orange body
that does not soot, the shutter opening must be
adjusted between these two extremes.
Air Shutter Adjustment Guidelines
• If there is smoke or soot present, rst check
the log set positioning to ensure that the
flames are not impinging on any of the logs.
If the log set is properly positioned and a
sooting condition still exists, then the air
shutter opening should be increased.
• The more offsets in the vent system, the larger
the air shutter opening will need to be.
• An appliance operated with the air shutter
opened too far, may have flames that appear
blue and transparent. These weak, blue and
transparent flames are termed anemic.
• Propane models may exhibit flames which
candle or appear stringy. If this is present
and persists, adjust the air shutter to a more
closed position, then operate the appliance
for a few more minutes to ensure that the
flame normalizes and the flames do not
appear sooty.
The following chart is provided to aid you in
achieving the correct air shutter adjustment
for your installation.