8
Design the duct work according to methods
described by the National Warm Air Heating
and Air Conditioning Association (ACCA). The
ducts must be properly sized not to exceed .2”
w.c. pressure drop at 400 scfm per nominal ton
of cooling capacity.
Duct work should be attached directly to the unit
fl anges for horizontal applications.
Installation of Square-to-Round Adapters
—
The square-to-round adapter panel and 14”
round collars must be removed from the return
inlet opening.
1) Remove the close-off plates from the supply
and return openings.
2) Fit the 14” collar inside the adapter plate
and secure.
3) Place the square-to-round adapter plate,
one over each opening, and attach with
sheet metal screws.
4) Seal around the adapter box and collars.
Refer to Figure 7 for installation.
Unconditioned Spaces —
All duct work passing
through unconditioned space must be properly
insulated to minimize duct losses and prevent
condensation. Use insulation with an outer vapor
barrier. Refer to local codes for insulation material
requirements.
Acoustical Duct Work —
Certain installations
may require the use of acoustical lining inside
the supply duct work. Acoustical insulation must
be in accordance with the current revision of the
Sheet Metal and Air Conditioning Contractors
National Association (SMACNA) application
standard for duct liners. Duct lining must be UL
classifi ed batts or blankets with a fi re hazard
classifi cation of FHC-25/50 or less. Fiber duct
work may be used in place of internal duct liners
if the fi ber duct work is in accordance with the
current revision of the SMACNA construction
standard on fi brous glass ducts. Fibrous duct
work and internal acoustical lining must be NFPA
Class 1 air ducts when tested per UL Standard
181 for Class 1 ducts.
Horizontal to Down fl ow Conversion —
The unit
is shipped ready for horizontal duct connections.
If down fl ow ducts are required, the unit must be
converted following the steps below for both the
supply and return ducts.
1) Locate the duct cap inside the duct openings
and remove the screw holding it in place.
2) Lift the cap out of the unit. (The cap can
be pushed up from the bottom by reaching
through the fork slot).
3) Cover the horizontal duct opening with the
cap. The insulation will be on the indoor
side.
4) Fasten the cover with screws and seal to
prevent air leakage.
Clearance —
These units are approved for 0
inch clearance.
Locating and Installing the Return
Air Assembly
To avoid complications, locate and install the
return air assembly fi rst. The return air box with
grille and fi lter (Figure 8) 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,
2"
Figure 6. Ground Level Installation
Figure 7. Supply and Return Duct Fittings
