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NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT
®
PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
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 sooting,
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.
1. Refer to Figures 61, 62 and 63 for proper
flame appearance. To adjust the flame, rotate
the adjustment rod toward the back or toward
the front of the fireplace (rod located in the
lower control area). Position the air shutter
to the factory setting as shown in the table
in Figure 64.
2. Light appliance (follow lighting procedure
on lighting label in control compartment or
in the Care and Operation Instructions).
3. Allow the burner to operate for at least 15
minutes while observing the flame continu-
ously to ensure that the proper flame ap-
pearance has been achieved. If the following
conditions are present, adjust accordingly.
• If flame appears weak or sooty, adjust
the air shutter, incrementally, to a more
open position until the proper flame
appearance is achieved.
• If flame remains blue, adjust the air
shutter, incrementally, to a more closed
position until the proper flame appear-
ance is achieved.
4. Leave the control knob (OFF/PILOT/ON)
in the ON position and the burner ON/OFF
switch (and remote switches, if applicable)
in the OFF postion.
5. When satisfied that the burner flame appear-
ance is normal, reinstall the lower control
compartment door, then proceed to finish
the installation.
Figure 61 MPD-3328 MODEL
Figure 62 MPD-3530 MODEL
Figure 63 MPD-4035 AND MPD-4540 MODEL