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GPac Users Information 7/07-2
c. The supply air and return air duct connections to verify that they are physically sound, are sealed to the
furnace casing. (See
Porting and Ductwork
section of the Installation Instructions.)
d. To make certain that there are no signs of deterioration of the unit and that the unit is physically sound
without cracks, gaps or sagging.
e. The condensate line to make sure that condensate can flow free from the unit and the line is not
obstructed.
f. The air filters to make certain that they are not dirty. Clean and/or replace as required. The fiberglass
disposable type should be REPLACED before they become clogged. Dirty filters are can severely
restrict air flow and are a common cause of complaints of inadequate heating and cooling.
Filters are located behind the front panel. To change the filter, remove the front panel and slide the
filters out. Replacement filters should be ONLY of the type and size as the original Marvair supplied
filters.
g. To verify that the burner flame is in good adjustment.
Allow the unit to operate for a few minutes to establish normal burning conditions. Look at the flames
on the burners. They should be predominately blue in color and robust in appearance. The flame
should be in the middle of the heat exchanger tubes. Check to see that all the burners are lit and that
the flame does not impinge on the sides of the heat exchanger. Observe the flame. There should be
little or no change to in the shape or size of the flame. Changes in the shape and size of the flame may
indicate a leak in the heat exchanger. See figure 1.
Distorted flame or yellow tips of the natural gas flame or long yellow tips on LP gas flames may be
caused by one or more of the following:
1. lint or dirt inside the burner or burner ports,
2. lint or dirt at the air inlet between the burner and the manifold pipe, or
3. an obstruction over the burner plate.
If any of these are visible, turn the unit off and use a vacuum or a soft brush to clean the affected areas.
It is recommended that the unit be inspected by a qualified service technician to thoroughly check and inspect
the unit prior to each heating season.
Figure 1. Burner Flame
Start-up
Before lighting the unit, smell around the unit for gas. Be sure to smell next to the floor because LP gas is heavier
than air and will settle on the floor.
The gas valve on your unit is equipped with an ON/OFF knob. Use only your hand to turn the knob Never use
tools. If the knob will not push in or turn by hand, do not try to repair it. Call a qualified service technician. Force
or attempted repair may result in a fire or explosion.
