Millivolt Appliance Checkout; Electronic Appliance Checkout - Lennox MERIT PLUS SERIES Homeowner's Care And Operation Instructions Manual

The following chart is provided to aid you in
achieving the correct air shutter adjustment
for your installation.
Air Shutter Adjustment Guidelines
Amount of Flame
Primary Air Color
If air shutter is Flame will
closed too far be orange
If air shutter is Flame will
open too far be blue
WARNING
Air shutter adjustment should
only be performed by a qualifi ed
professional service technician.
WARNING
Ensure front glass panels are in
place and sealed during adjust-
ment.
CAUTION
The air shutter door and nearby
appliance surfaces are hot. Exer-
cise caution to avoid injury while
adjusting fl ame appearance.
CAUTION
Carbon will be produced if the air
shutter is closed too much. Any
damage due to carboning result-
ing from improperly setting the
air shutter is not covered under
the warranty.
Burner Air Shutter Adjustment Procedure
1. Locate adjustment rod and adjust air shutter
to the standard setting as shown in Figure
14 (adjustment rod is located in the lower
control compartment). 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
homeowners manual).
3. Allow the burner to operate for at least 15 min-
utes while observing the fl ame continuously
:
to ensure that the proper fl ame appearance
has been achieved (see Figure 13). If the
Air Shutter
following conditions are present, adjust
Adjustment
accordingly.
• If flame appears weak or sooty, adjust
Air shutter
the air shutter, incrementally, to a more
gap should be
increased
open position until the proper fl ame
appearance is achieved.
Air shutter
• If fl ame stays lowered blue, adjust the
gap should be
air shutter, incrementally, to a more
decreased
closed position until the proper fl ame
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 satisfi ed that the burner fl ame appear-
ance is normal, close the lower control
compartment door.
Decrease Shutter Opening
In This Direction
Air Shutter
Adjusting
Rod
Main Burner Factory Air Shutter
Opening Setting - All Models
Model
MPD35ST
Figure 14

Millivolt Appliance Checkout

The pilot fl ame should be steady, not lifting
or fl oating. 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" minimum (tip)
of the quick drop out thermocouple should be
engulfed in the pilot fl ame. The fl ame should
project 1" (25 mm) beyond the hood at all three
ports. See Figure 15.
To light the burner, refer to the lighting instruc-
tions on Page 17.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Note - Burners are
omitted in this
view for clarity.
Orifi ce
Increase Shutter Opening
In This Direction
Ref. Air shutter Patent:
U.S. Pat. 5,553,603
Natural Propane
Gas Gas
1/8" 1/4"
3.2mm 6.4mm
Adjustment Rod Positions
(when viewed from above)
MILLIVOLT PILOT ASSEMBLY
Proper Pilot Flame Appearance
Hood
Thermocouple
Pilot
Nozzels
Thermopile
Figure 15

Electronic Appliance Checkout

To light the burner, refer to the lighting instruc-
tions on Page 19. Ensure the igniter lights the
pilot. The pilot fl ame should engulf the fl ame
sensor as shown in Figure 16.
ELECTRONIC PILOT ASSEMBLY
Proper Pilot Flame Appearance
Proper Flame
Adjustment
Pilot
Nozzels
Figure 16
With proper care and maintenance, your appli-
ance will provide many years of enjoyment. If
you should experience any problem, fi rst refer
to the troubleshooting guide in this manual.
If problem persists, contact your Lennox
distributor.
Igniter Rod
3/8" Min.
(9 mm)
3/8" to 1/2"
(9 -13 mm)
Ground
Electrode
Flame Rod
Hot Surface
Igniter
11