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10
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX MERIT
®
SERIES B-VENT GAS FIREPLACES • 42" LMBV MODELS • INSTALLATION INSTRUCTIONS
When satisfied that the appliance operates
properly, proceed to finish the installation.
Leave the control knob/lever in “ON” position
and turn the remote switch “OFF.” Replace the
refractory access panel.
Figure 21
Adjustment
To adjust the ame, position the air shutter to the
nominal setting (Figure 21 ). Allow the burner
to operate for at least 30 minutes. Observe the
ame 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 venting 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. Reassemble
and restart the appliance and after 30 minutes
reobserve the flame. Adjust the air shutter as
described.
Figure 20
Proper Flame
Adjustment
Hot Surface
Igniter
Flame Rod
Ground
Electrode
3/8 To 1/2 Inch
(9 mm to 13 mm)
Step 10. Adjustments – The following para-
graphs address adjustment concerns and
procedures.
Flame Appearance and Sooting
Proper ame appearance is a matter of taste.
Generally most people prefer the warm glow of
a yellow to orange ame. Appliances operated
with air shutter openings that are too large, or
with long vertical vent runs, will exhibit ames
that are blue and transparent. These weak, blue
and transparent ames are termed anemic.
If the air shutter opening is too small 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. Soot-
ing is caused by incomplete combustion in the
ames and a lack of combustion air entering
the air shutter opening.
To achieve a warm yellow to orange ame with
an orange body that does not soot, the shutter
opening must be adjusted between these two
extremes.
No smoke or soot should be present. Reposition
the log set if the ames impinge on any of them.
If sooting conditions exist, the air shutter
opening on the main burner can be adjusted.
Normally, the more offsets in the vent system,
the greater the need for the air shutter to be
opened further.
WARNING: AIR SHUTTER ADJUSTMENT
SHOULD ONLY BE PERFORMED BY A
QUALIFIED PROFESSIONAL SERVICE
TECHNICIAN.
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