Maytag Goodman GM9C96 Service And Troubleshooting page 17

SYSTEM OPERATION
Upflow Models
*0403A* 1 - 16 X 25 Side or 1 - 14 X 24 Bottom Return
*0603A* 1 - 16 X 25 Side or 14 X 24 Bottom Return
*0603B*
*0803B*
*0804B*
*0804C*
*0805C*
*0805D* 2 - 16 X 25 Side or 1 - 20 X 25 Bottom Return¹
*1004C* 2 - 16 X 25 Side or 1 - 20 X 25 Bottom Return
*1005C* 2 - 16 X 25 Side or 1 - 20 X 25 Bottom Return
*1205D* 2 - 16 X 25 Side or 1 - 24 X 24 Bottom Return
Downflow Models
*0403A*
*0603A*
*0804B*
*1005C*
Larger filters may be used, filters may also be centrally located
¹ = Use 2 - 16 X 25 filters and two side returns or 20 X 25 filter on bottom
return if furnace is connected to a cooling unit over 4 tons nominal capacity
A combination of one side & bottom may be used instead of both sides
Horizontal Installations
Filter(s) must be installed external to the furnace casing for
horizontal installations. For most installations it is preferable
to use a central return with filters installed in the duct behind
the return air grill. In this way filter replacement is relatively
simple by merely removing the grille, rather than going into
the attic or crawl space.
ADDITIONAL FILTERING ACCESSORIES
External Filter Rack Kit (EFR02)
The external filter rack kit is intended to provide a location
external to the furnace casing, for installation of a permanent
filter on upflow model furnaces. The rack is designed to mount
over the indoor blower compartment area of either side panel,
and provide filter retention as well as a location for attaching
return air ductwork.
Combustion Quality
Combustion quality can be affected by several factors. Major
factors are venting and draining.
Venting
The venting system should be planned and installed with the
following in mind;
• Should not be longer than necessary
• Use 45°elbows rather than 90° elbows when possible
• Must not sag or otherwise trap condensate
• Use longest radius fittings possible
• If using 3" venting, make the transition from 2" to 3" as
close as practically possible
• Make sure there is no flue gas recirculation into the
combustion air pipe
Condensate Drainage
Furnace combustion can be affected if a furnace is holding
condensate. Check for proper connections of drain hoses,
Minimum Recommended Filter Size
1 - 16 X 25 Side or Bottom Return
1 - 16 X 25 Side or Bottom Return
1 - 16 X 25 Side or Bottom Return
1 - 16 X 25 Side or Bottom Return
1 - 16 X 25 Side or Bottom Return¹
2 - 10 X 20 or 1 - 14 X 25 Top Return
2 - 10 X 20 or 1 - 14 X 25 Top Return
2 - 14 X 20 or 1 - 16 X 25 Top Return
2 - 14 X 20 or 1 - 20 X 25 Top Return
make sure furnace condensate trap is clean. Make sure
furnace is not improperly sloped. Make sure air conditioning
coil drain is not interfering with furnace drain.
Other Causes
1. Manifold Gas Pressure must be set for the gas being used,
Natural or L.P., high and low firing rates. If converted to
L.P. gas, check size of all orifices
2. Remove Draft Inducer, Check the integrity of the gasket
between the inducer and the collector box cover, any
air leak here will have a negative effect on combustion.
Check the orifice hole in the collector box, it must be free
of burrs on both sides
3. Make sure burners are clean, not out of position and line
up correctly with exchanger tubes, including the heat
exchanger orifice plate between the burners and the
heat exchanger tubes, make sure it is not loose, missing
a screw or hanging down between the burners and heat
exchangers causing flame impingement.
4. Make sure the field installed gas line is not binding and
causing distortion of burner assembly
5. If the furnace is installed as a one pipe system; make
sure the surrounding area and structure are adequate to
provide combustion air
6. Make sure there are no cabinet air leaks allowing supply
air to affect combustion
7. If heat exchanger integrity is uncertain, follow procedures
in Service Bulletin SF-041
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