Lennox MPGA 050 B3, Application Manual

Page: 33 / 37

The vent from your furnace may rise vertically and
terminate above the roof. When horizontal venting an
80% furnace, an approved sidewall venter must be used.
Refer to the installation instructions for further information
on horizontal venting of an 80% furnace.
Make sure all flue product carrying areas and materials
external to the furnace (i.e vent terminals, etc..) are clear
and free of any obstruction, slope upward, and have no
holes or leaks.
Check to see that the furnace cabinet is sound and firmly
supported, without sagging. There should be no cracks
or gaps between the furnace and the base or floor, which
would permit entry of unfiltered air.
It is important that the outside area where the vent
terminates is kept clear of any obstructions which might
block or impede the venting of the furnace. Should
venting become blocked at anytime, your furnace is
equipped with a special safety control to prevent
operation of the furnace until the condition has been
corrected. Contact your dealer if you desire more
information about this safety feature.
Should any unusual conditions be observed during your
inspections, call an authorized service dealer immediately.
For proper venting terminations, see the Installation
Instructions furnished with the furnace.
Return Air
Ascertain that all return air duct connections are tight and
sealed to the furnace cabinet and that all return air grilles
or registers are located outside the space containing the
furnace.
Cleaning/Replacing the Filter
It is very important to clean or replace the air filter
regularly. Dirty filters are the most common cause of
inadequate heating or cooling performance and can
sharply increase the operational costs of your unit. In
some cases, they can double the cost.
The air filter
should be inspected at least every 6 weeks and
cleaned or replaced as required.
Your furnace may use either a disposable filter or a
permanent filter. The type of filter may be indicated on a
label attached to the filter. If a disposable filter is used,
replace with the same type and size. If a permanent filter
is used, clean filter and place back in furnace. To clean
a permanent filter, shake filter to remove excess dirt
and/or use a vacuum cleaner. Wash filter in soap or
detergent water and replace after filter is dry. Permanent
filters do not need to be oiled after washing.
Permanent filters may be replaced with disposable filters.
Refer to Table 1 when selecting the proper size and
quantity of disposable filter.
If your air distribution system has a central return air filter-
grille, you do not need a filter in your furnace. Clean the
filter-grille the same way permanent filters are cleaned.
Table 1 EXTERNAL FILTER RACK SIZE
SIDE
RETURN
BOTTOM/END
RETURN
15 ½ X 25 12 X 25
15 ½ X 25 15 ½ X 25
15 ½ X 25 19 X 25
Safety Interlock Switch
The blower compartment door on your high efficiency gas
furnace is equipped with a safety interlock switch that will
automatically shut off your complete system (including
blower) once the door is removed. This is for your
personal safety. Be sure to check your furnace for proper
operation once the door or panel has been replaced.
If the system does not operate once the panel has been
replaced, try removing and replacing it once again. If the
furnace still does not operate, call your dealer for service.
Rollout Switch
This unit is equipped with a manual reset high
temperature sensor or rollout switch. In the unlikely event
of a sustained main burner flame rollout, the rollout switch
will shut off the flow of gas by closing the main gas valve.
The switch is located inside the gas burner area. Flame
rollout can be caused by blockage of the power vent
system, a blocked heat exchanger, or improper gas
pressure or adjustment. If this event occurs, the unit will
not operate properly. The gas supply to the unit should
be shut off and
no attempt should be made to place it
in operation . The system should be inspected by a
qualified service technician.
Lubrication
Lubrication of the bearings in the circulating air blower
motor and the combustion blower motor is not
recommended.
Burner Flame
While the furnace is in operation, observe the main
burner flames. Compare these observations to Figure 3
to determine if proper flame adjustment is present. If
your observations indicate improper flame adjustment, call
your authorized service dealer for service.
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