18
America” Manual D.
A duct system must be installed in accordance with Stan-
dards of the National Board of Fire Underwriters for the In
-
stallation of Air Conditioning, Warm Air Heating and Ventilat-
ing Systems. Pamphlets No. 90A and 90B.
A closed return duct system must be used, with the return
duct connected to the furnace.
NOTE:
Ductwork must nev-
er be attached to the back of the furnace. For installations
requiring more than 1800 CFM, use a bottom return or two
sided return. Supply and return con nections to the furnace
may be made with flexible joints to reduce noise transmis
-
sion. To prevent the blower from inter fering with combustion
air or draft when a central return is used, a connecting duct
must be installed between the unit and the utility room wall.
Furnace is shipped with the top flanges in the flat position.
Before installing a coil or ducts, the flanges must be bent
90°. A room, closet, or alcove must not be used as a return
air chamber.
When the furnace is used in connection with a cooling unit,
the furnace should be installed in parallel with or on the
upstream side of the cooling unit to avoid condensa tion in
the heating element. With a parallel flow arrange ment, the
dampers or other means used to control the flow of air must
be adequate to prevent chilled air from entering the furnace
and, if manually operated, must be equipped with means to
prevent operation of either unit unless the damper is in the
full heat or cool position.
When the furnace is installed without a cooling coil, it is rec-
ommended that a removable access panel be provided in
the outlet air duct. This opening shall be accessible when the
furnace is installed and shall be of such a size that the heat
exchanger can be viewed for visual light inspection or such
that a sampling probe can be inserted into the airstream. The
access panel must be made to prevent air leaks when the
furnace is in operation.
NOTE: In a horizontal installation the air condition
-
ing coil must be adequately supported by proper
brackets and supports. Inadequate coil support can
result in furnace cabinet distortion and air leakage.
When the furnace is heating, the temperature of the return
air entering the furnace must be between 55°F and 100°F.
When a furnace is installed so that supply ducts carry air
circulated by the furnace to areas outside the space con-
taining the furnace, the return air shall also be handled by a
duct sealed to the furnace casing and terminating outside the
space containing the furnace.
Filters - Read This Section Before
Installing The Return Air Ductwork
Filters must be used with this furnace. Filters do not ship
with this furnace, but must be provided by the installer. Filters
must comply with UL900 or CAN/ULCS111 standards. Dam
-
age or repairs due to failure to install filters in the furnace are
not covered under the warranty.
Depending on the installation and/or customer preference,
differing filter arrangements can be applied. Filters can be
installed in the central return register or a side panel external
filter rack kit (upflows), or the ductwork above a downflow
furnace. As an alternative, a media air filter or electronic air
cleaner can be used as the primary filter.
One of the most common causes of a problem in a forced air
heating system is a blocked or dirty filter. Air filters must be
inspected monthly for dirt accumulation and replaced if nec-
essary. Failure to maintain clean filters can cause premature
heat exchanger failure.
A new home may require more frequent replacement until
all construction dust and dirt is removed. Air filters 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 = 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
SEQUENCE OF OPERATION
(INTEGRATED IGNITION CONTROL)
Refer to Timing Charts for sequencing.
Power Up
• 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.
Heating Mode
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
