035-17443-000 Rev. A (800)
8
Unitary Products Group
DUCTWORK
The duct system design and installation must:
1.
Handle an air volume appropriate for the served space
and within the operating parameters of the furnace spec-
ifications.
2.
Be installed in accordance with standards of NFPA
(National Fire Protection Association) as outlined in
NFPA pamphlets 90A and 90B (- latest editions).
3.
Create a closed duct system. The supply system must
be connected to the furnace outlet and the return duct
system must be connected to the furnace inlet. Both sup-
ply and return duct systems must terminate outside the
space containing the furnace.
4.
Generally complete a path for heated or cooled air to cir-
culate through the air conditioning and heating equip-
ment and to and from the conditioned space.
When the furnace is used in conjunction with a cooling coil,
the coil must be installed parallel with, or in the supply air
side of the furnace to avoid condensation in the primary heat
exchanger.
When a parallel flow arrangement is used, the dampers or
other means used to control air flow must be adequate to pre-
vent chilled air from entering the furnace, and if manually
operated, must be equipped with means to prevent operating
of either unit unless the damper is in the full heat or cool posi-
tion.
UPFLOW APPLICATIONS
SUPPLY PLENUM CONNECTION
Attach the supply plenum to the furnace
outlet duct connection flanges. This is
typically through the use of S cleat mate-
rial when a metal plenum is used. The
use of an approved flexible duct connec-
tor is recommended on all installations.
This connection should be sealed to pre-
vent air leakage.
If a matching cooling coil is used, it may
be placed directly on the furnace outlet
and sealed to prevent leakage. Follow the
coil instructions for installing the supply
plenum.
On all installations without a coil, a removable access panel
is recommended in the outlet duct such that smoke or
reflected light would be observable inside the casing to indi-
cate the presence of leaks in the heat exchanger. This
access cover shall be attached in such a manner as to pre-
vent leaks.
Return Duct Connection
Return air must enter the cabinet through the bottom only, or
a bottom and one side. Single or Dual side return only is not
allowed. Return air may not be connected into the rear
panel of the unit. See the specific type application installa-
tion for details. Be sure to see the “Filters” section of this
instruction and side-return detail (See Figure 2 ).
FILTER INSTALLATION
All applications require the use of a filter. All filters must be
field supplied and located outside the furnace cabinet in
either a filter rack, duct system or filter grille.
NOTE: All air velocities over 300 feet per minute, require the
use of high velocity filters.
The return air return requirements for this furnace consist of:
1.
Bottom Only Return = 536 Ft./Min.
2.
Bottom & Single Side = 390 Ft./Min.
3.
Bottom & Two-Sides = 300 Ft./Min.
The return duct may be attached to the furnace by “S-cleat,”
bend tabs or other approved methods. Be sure to seal the
duct to the furnace to prevent air leakage.
Where the return duct system is not complete, the return con-
nection must run full size to a location outside the utility room,
basement or space where furnace is installed. For further
details, consult Section 5.3 (Air for Combustion and Ventila-
tion) of the National Fuel Gas Code, ANSI Z223.1, or CAN /
CGA B149.1 or.2, Installation Code - latest editions.
NOTE: An external mounted (1SR0302) upflow side-return
accessory kit , which includes an aluminized mesh filter, is
available and is sized to fit the side knockouts on the cabinet.
The cooling coil must be installed in the supply air
duct downstream of the furnace.
All installations must have a filter installed.
