GMES80 Installation Manual
18
Depending on the installation and/or customer preference,
diering lter arrangements can be applied. Filters can be
installed in the central return register or a side panel external
lter rack kit (upows), or the ductwork above a downow
furnace. As an alternative, a media air lter or electronic air
cleaner can be used as the primary lter.
One of the most common causes of a problem in a forced air
heating system is a blocked or dirty lter. Air lters must be
inspected monthly for dirt accumulation and replaced if nec-
essary. Failure to maintain clean lters can cause premature
heat exchanger failure.
A new home may require more frequent replacement until
all construction dust and dirt is removed. Air lters are to be
installed in the return air duct external to the furnace cabinet.
Upflow / Horizontal
Models
Minimum Recommended Filter Size^
*0403A* 1 - 16 X 25 Side or 1 - 14 X 24 Bottom Return
*0603A* 1 - 16 X 25 Side or 1 - 14 X 24 Bottom Return
*0604B* 1 - 16 X 25 Side or Bottom Return
*0803B* 1 - 16 X 25 Side or Bottom Return
*0804B* 1 - 16 X 25 Side or Bottom Return
*0805C* 2 - 16 X 25 Side or 1 - 20 X 25 Bottom Return
*0805D* 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 Minimum Recommended Filter Size^
*0403A* 2 - 10 X 20 or 1 - 14 X 25 Top Return
*0603A* 2 - 10 X 20 or 1 - 14 X 25 Top Return
*0804B* 2 - 14 X 20 or 1 - 16 X 25 Top Return
*1005C* 2 - 14 X 20 or 1 - 20 X 25 Top Return
^ Larger filters may be used, filters may also be centrally located
¹ = us e 2 - 16 X 25 filters and two si de returns or 20 X 25 fi l ter on bottom
return if furnace is connected to a cooling unit over 4 tons nominal capacity
Sequence of Operation (Intergrated Ignition Control)
Refer to Timing Charts for sequencing.
• 115 VAC power applied to furnace.
• Integrated ignition control performs internal checks.
• Integrated ignition LED will light.
• Integrated ignition control monitors safety circuits
continuously.
• Furnace awaits call from thermostat.
The normal operational sequence in heating mode is as
follows:
• R and W thermostat contacts close, initiating a call for
heat.
• Integrated control module performs safety circuit
checks.
• Induced draft blower is energized for 15 second pre-
purge period causing pressure switch contacts to close.
• Igniter warm up begins after 15 second prepurge
expires.
• Gas valves open at end of igniter warm up period,
delivering gas to burners and establishing ame.
• Integrated control module monitors ame presence.
Gas valve will remain open only if ame is detected.
• Circulator blower is energized on heating speed
following a fixed thirty second blower on delay.
Electronic air cleaner terminals are energized with
circulator blower.
• Furnace operates; integrated control module monitors
safety circuits continuously.
• R and W thermostat contacts open, completing the call
for heat.
• Gas valve closes, extinguishing ame.
• Induced draft blower is de-energized following a fteen
second post purge.
• The circulator blower remains on heating speed for the
selected heat o delay period.
• Furnace awaits the next call from thermostat.
The normal operational sequence in cooling mode is as
follows:
• R and Y thermostat contacts close, initiating a call for
cool.
• Integrated control module performs safety circuit
checks.
• Outdoor fan and compressor are energized.
• Circulator blower is energized on cool speed following
a xed ve second on delay. Electronic air cleaner
terminals are energized with circulator blower.
• Furnace circulator blower and outdoor cooling unit
run, integrated control module monitors safety circuits
continuously.
• R and Y thermostat contacts open, completing the call
for cool.
• Outdoor fan and compressor are de-energized.
• Circulator blower is de-energized following a xed forty
ve second cool o delay period. Electronic air cleaner
terminals are de-energized.
• Furnace awaits the next call from thermostat.
The normal operational sequence in fan only mode is as
follows:
• R and G thermostat contacts close, initiating a call for
fan.
• Integrated control module performs safety circuit
checks.