PRODUCT DESIGN
33
Upflow furnaces with air delivery of less than 1800 CFM:
Use one side return or one bottom return ductwork con-
nection.
Upflow furnaces with air delivery of 1800 CFM or higher:
Use two side returns or bottom return connection.
Guide dimples locate the side and bottom return cutout lo-
cations. Use a straight edge to scribe lines connecting the
dimples. Cut out the opening on these lines. An undersized
opening will cause reduced airflow. For bottom return con
-
nection, remove the bottom of the cabinet before setting the
furnace on the raised platform or return air duct.
A closed return duct system must be used, with the return
duct connected to the furnace.
NOTE:
Ductwork must never
be attached to the back of the furnace.
Supply and return
connections to the furnace may be made with flexible joints
to reduce noise transmission, if desired. If a central return is
used, a connecting duct must be installed between the unit
and the utility room wall so the blower will not interfere with
combustion air or draft. The 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 condensation in
the heating element. With a parallel flow arrangement, 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 heating, the temperature of the return
air entering the furnace must be between
55°F
and
100°F
.
UPRIGHT FILTER INSTALLATIONS
Depending on the installation and/or customer preference,
differing filter arrangements can be applied. Filters can be
installed in the central return register and a side panel exter-
nal filter rack kit (upflow filter kit # EFR01). As an alternative
a media air filter or electronic air cleaner can be used as the
requested filter. Refer to the following minimum filter require
-
ment charts for determination of the minimum filter area to
ensure proper unit performance.
COUNTERFLOW FILTER INSTALLATION
This furnace has provisions for the installation of return air
filters at the counterflow top return. Refer to Minimum Filter
Area tables to determine filter area requirement.
NOTE:
Filters can also be installed elsewhere in the duct
system such as a central return.
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 (EFR01)
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.
NORMAL SEQUENCE OF OPERATION
P
owEr
u
P
1. 115 VAC power applied to furnace.
2. Integrated ignition control module performs internal
checks.
3. Integrated ignition control module LED will light.
4. Integrated ignition control monitors safety circuits contin-
uously.
5. Furnace awaits call from thermostat.
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*
1 - 16 X 25 Side or Bottom Return¹
*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
^ Other size filters of equal or greater dimensions 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