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Figure 5. Return Air Box
INSTALLING RETURN AND
SUPPLY AIR FITTINGS
The supply and return fi ttings are included with
the unit and located in the supply duct. They
attach to the unit openings (Figure 4) with a
fl ange and bead arrangement and may be,
secured with two sheet metal screws. Note: For
easier access, install fi ttings before positioning
unit in fi nal location.
Supply Duct
1. Position the supply duct collar so the edge of
the unit opening fi ts between the fl ange and
the bead.
2. Overlap the collar ends keeping the small
screw holes underneath.
3. Align the holes in the crimped area and install
one screw. Note: It may be necessary to loosen
the four screws that hold the transition duct
in order to install the supply fi tting. Re-tighten
when installation is complete.
4. Tap collar (if necessary) to ensure engagement
with unit opening and install second screw.
5. Tighten fi rst screw and rotate collar clockwise
so joint is near three o’clock position.
Return Duct
1. Align the slots with the holes in the collar and
install two screws.
2. Position the collar over the opening and align
the four notches in the collar with the four
dimples in the panel.
3. Using self-drilling screws (10-16x.5) attach
the collar to the rear panel.
LOCATING AND INSTALLING THE
RETURN AIR ASSEMBLY
To simplify installation, locate and install the
return air assembly fi rst. If desired, the return
opening can be located inside a closet with
louvered doors that has an open area equal to
or greater than the 12” x 20” grille furnished. The
return air grille can be placed in the wall of a closet
and the air ducted into the fi lter box through a
boxed-in area at the closet fl oor level. Make sure
the fi lter is readily accessible.
NOTE: The return air box with grille and fi lter
(Figure 5) should not be located in heavy traffi c
areas like hallways or center of rooms. A good
spot is in a corner or under a table, if a minimum
two inch clearance is available.
1. Start the installation from under the home by
cutting a small hole in the subfl oor. Determine
how the fl oor joist location will affect cutting
the opening needed for the return air box.
NOTE: Floor joists are generally located on
16” centers, leaving 14-3/8” between joists.
2. After measuring the return air box
(approximately 12-1/4” x 20-1/4”), cut the
hole through the fl oor so that the box will fi t
between the fl oor joists. Care should be taken
when cutting through carpeting to avoid snags.
NOTE: In most installations it will be necessary
to cut a similar hole in the fi berboard directly
under the hole in the fl oor. However, if the fl oor
is more than ten inches deep, it will only be
necessary to cut a hole for the collar on the
return air box or for the insulated duct.
3. Set the box into the opening and fasten with
screws or nails.
4. Put the fi lter and return air grille in place.
Figure 4. Return and Supply Air Fittings
Supply Air
14” Duct Dimples
Return Air
Transition Duct Screws