10 18-CD30D1-12
Installer’s Guide
With a parallel flow arrangement, the dampers or other
means used to control flow of air shall 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
full heat or cool position.
On any job, flexible connections of nonflammable material
may be used for return air and discharge connections to
prevent transmission of vibration. Though these units
have been specifically designed for quiet, vibration free
operation, air ducts can act as sounding boards and could,
if poorly installed, amplify the slightest vibration to the
annoyance level.
When the furnace is located in a utility room adjacent to
the living area, the system should be carefully designed
with returns to minimize noise transmission through the
return air grille. Although these furnaces are designed
with large blowers operating at moderate speeds, any
blower moving a high volume of air will produce audible
noise which could be objectionable when the unit is
located very close to a living area. It is often advisable
to route the return air ducts under the floor or through
the attic. Such design permits the installation of air return
remote from the living area (i.e. central hall).
When the furnace is installed so that the supply ducts
carry air circulated by the furnace to areas outside
the space containing the furnace, the return air shall
also be handled by a duct(s) sealed to the furnace and
terminating outside the space containing the furnace.
RETURN AIR DUCT SYSTEMS
Safety Hazard
Sharp Edge Hazard
Be careful of sharp edges on equipment or any cuts
made on sheet metal while installing or servicing.
Personal injury may result.
Where there is no complete return duct system,
the return connection must be run full size from
the furnace to a location outside the utility room,
basement, attic, or crawl space.
Do NOT install return air through the back of the furnace
cabinet.
Do NOT install return air through the side of the furnace
cabinet on horizontal applications.
NOTE:
Minimum return air temperature is 55°F.
PREPARATION FOR UPFLOW BOTTOM AND SIDE
RETURN AIR FILTER INSTALLATION
All return air duct systems should provide for installation
of return air filters.
1. Determine the appropriate position to set the furnace
in order to connect to existing supply and return
ductwork.
2. The return air filter is shipped in either the bottom or
side location. Remove the filter by first turning the
two latches on the blower door and tilting the door
forward to remove. Remove the filter by sliding it out.
3. For upflow side return installations, remove the
insulation around the opening in the blower
compartment.
4. The side panels of the upflow furnace include
locating notches that are used as guides for cutting
an opening for return air, refer to Figure 10 and
the outline drawing on page 4 for duct connection
dimensions for various furnaces.
5. If a 3/4" flange is to be used for attaching the air inlet
duct, add to cut where indicated by dotted lines in
Figure 10. Cut corners diagonally and bend outward
to form flange.
6. If flanges are not required, and a filter frame is
installed, cut between locating notches (See Figure
10).
7. The bottom panel of the upflow furnace must be
removed for bottom return air. After removing the
filter, lay the furnace on its back. Remove the two
5/16" hex screws securing the front of the bottom
channel to the cabinet.
UPFLOW FURNACE ONLY
*SEE OUTLINE DRAWING
FRONT
of Furnace
LOCATING NOTCH-
ES PROVIDED FOR
SIDE RETURN
CUTOUT
0
CUT OUT FOR
SIDE FILTER
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