12
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT
®
SERIES B-VENT GAS FIREPLACES • 36" LMBV MODELS • CARE AND OPERATION INSTRUCTIONS
Figure 14 - Burner Flame Appearance
When satisfied that the appliance operates
properly, leave the control knob/lever in “ON”
position and turn the remote switch “OFF.”
Replace the refractory access panel.
Figure 15
burner Flame Adjustments
To adjust the flame, position the air shutter to the
nominal setting
(
Figure 15
)
. Allow the burner
to operate for at least 30 minutes. Observe the
flame continuously. If it appears weak or sooty
as previously described, adjust the air shutter
open or closed until desired effect is achieved.
NOTE:
If the flame still appears anemic
with the air shutter closed all the way
(usually a result of lengthy vertical vent-
ing runs), turn off the appliance, turn off
the gas supply, wait for the parts to cool
and access the air shutter. The shutter is
prevented from actually closing by a tab
that is bent over into the opening. Remove
this obstruction by bending back. Reas-
semble and restart the appliance and after
30 minutes reobserve the flame. Adjust
the air shutter as described.
Orifice
Air Shutter
Burner Tube
Adjusting
Set Screw
Nominal Air Shutter Settings
Natural Gas - 1/16" (1.59 mm) Open
Propane Gas - 1/4" (6.35 mm) Open
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
bURNER ADJUSTMENTS
(QUALIFIED TECHNICIANS ONLY)
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, first 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.
WARNING
•
Air shutter adjustment should
only be performed by a quali-
fied professional service tech-
nician.
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.
Nominal Air Shutter Settings
Natural Gas - 1/16" (1.59 mm) Open
Propane Gas - 1/4" (6.35 mm) Open
