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NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Volcanic Stone
Air Shutter
Adjustment Lever
Figure 51: Burner Flame Appearance — Control Side
Figure 52: Burner Flame Appearance — Opposite Control Side
Volcanic Stone
1. Light the appliance (follow lighting proce-
dure in Care and Operation Instructions or
on lighting label in control compartment).
2. Allow the burner to operate for at least 30
minutes while continuously observing the
flame to ensure that the proper flame ap-
pearance has been achieved (see Figures
51 and 52).
3. Adjust the air shutter using the lever on the
lower right side of the rebox (Figure 51).
• For more OPEN air shutter, slide lever
to the RIGHT.
• For more CLOSED air shutter, slide
lever to the LEFT.
A minimum shutter setting is designed into
the venturi by four 1/16"-inch tabs.
• If the ame appears weak or sooty (as
described on the previous page), adjust
the air shutter until proper flame appear-
ance is achieved.
• If ame stays lowered blue, incremen-
tally adjust the air shutter to a more
CLOSED position until proper flame
appearance is achieved.
Note: See Figures 51 and 52 for proper burner
flame appearance.
WARNING
HOT GLASS WILL CAUSE BURNS.
DO NOT TOUCH GLASS UNTIL COOLED.
•Fireplace surfaces get EXTREMELY HOT!
•The glass on the front of the fireplace
reaches EXTREMELY HIGH temperatures
and can cause severe burns if touched.
Even after the gas is turned off, fireplace
surfaces remain extremely hot.
CAUTION
RISK OF PERSONAL INJURY
OR PROPERTY DAMAGE.
• Air shutter adjustment should only be
performed by a qualified professional
service technician.
• 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.
LENNOX HEARTH PRODUCTS • MONTEBELLO
®
SEE-THROUGH DIRECT-VENT GAS FIREPLACES (LSM40ST-N / LSM40ST-P) • INSTALLATION INSTRUCTIONS
Burner Air Shutter Adjustment
Procedure
Step 11. BURNER ADJUSTMENTS
Flame Appearance and Sooting
Proper ame appearance is a ame that is blue
at the base and becomes yellowish-orange in
the body of the ame. When the appliance is
rst lit, the entire ame may be blue and will
gradually turn yellowish-orange during the first
30 minutes of operation. After 30 minutes of
operation, if the ame is blue, or if the ame 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 ames. 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 ames and lack of combustion air enter-
ing the air shutter opening. To achieve a warm
yellowish-orange ame 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 ames which
candle or appear stringy. If this is present
and persists, adjust the air shutter to a more
OPEN 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.
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