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650.64-N4
When the furnace is used in conjunction with a cooling coil, the
furnace must be installed parallel with, or on the upstream side of the
cooling unit 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 prevent
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
Supply Plenum Connection
Attach the supply plenum to the furnace outlet duct connection
flanges. This is typically through the use of "S" cleat material
when a metal plenum is used. The use of an approved flexible
duct connector is recommended on all installations. This con-
nection should be sealed to prevent 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 a removable access panel should be pro-
vided in the outlet duct such that smoke or reflected light would
be observable inside the casing to indicate the presence of
leaks in the heat exchanger. This access cover shall be at-
tached in such a manner as to prevent leaks.
Return Duct Connection
Return air must enter the furnace through both side(s) or
bottom depending on the type of application. See the specific
type application installation for details. Be sure to see the
"Filters" section of this instruction.
FILTERS
RECOMMENDED SIZE FOR FIELD SUPPLIED
HIGH VELOCITY FILTERS
Furnace CFM
2000
3000
All applications require the use of a filter(s). This may be through
the use of any of the standard filters supplied with the furnace or
field supplied methods:
To remove a filter from the side location, push the closed end
of the filter down until it clears the flange on the side panel,
which acts as a catch for the retainer. When the retainer is clear
of the flange, it will pivot in the loops. Swing the retainer toward
the center of the furnace. This will expose the fiter to allow
removal.to re-install the filter, simply reverse this procedure.
For bottom filter removal, use the following procedure:
Remove the toe piece at the bottom of the furnace by removing
the four sheet metal screws holding it in place and slide the
filter out of the furnace. To install the filter, reverse this proce-
dure.
Side Return
Locate and knock out the square corner locaters. These indi-
cate the size of the cutoff to be made in the furnace side panel
(see Figure 2).
Install the side filter rack following the instructions provided with
that accessory. If a filter(s) is provided at another location in the
return air system, the ductwork may be directly attached to the
furnace side panel.
6
heat or cool
position.
FILTER
Size
Sq. inches
(2) 16 x 20
640
(2) 20 x 25
1000
FIGURE 2 - SIDE RETURN CUTOUT MARKINGS
NOTE: Some accessories such as electronic air
cleaners and pleated media may require a larger side
opening.
CAUTION: All installations must have a filter installed.
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.
All applications require either return from two sides, and/or
bottom.
Where the return duct system is not complete, the return
connection must run full size to a location outside the utility
room or basement.
For further details, consult Section 5.3 (Air for Combustion and
Ventilation) of the National Fuel Gas Code, ANSI Z223.1, or
CAN/CGA B149.1 or .2, Installation Code - latest editions.
Bottom Return
Converting the furnace to open bottom return requires cutting
open the bottom panel as shown in Figure 3.
Bottom return applications normally pull return air through a
base platform or return air plenum. Return to Figure 3 for
opening dimensions.
Be sure the return air platform structure is suitable to support
the weiight of the furnace. Seal the furnace to the plenum to
prevent air leakage.
FIGURE 3- BOTTOM RETURN
(COMBUSTIBLE FLOOR)
Unitary Products Group
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