International comfort products N9MP1 Installation Instructions Manual page 40

Side Return Air Cutout
Figure 36
1
A = 14 / " Height of Cutout for 16" x 25" Filter
2
1
B = 22 / " Width of Cutout for 16" x 25" Filter
2
Embossed Area
on Side of Furnace
NOTE: Furnaces with 5 ton cooling rating may require both
(left and right) side return or one side and bottom return (see
notes in Circulation Air Blower Data). Side return air duct(s) is
not permitted with horizontal or downflow furnace
installation.
2. Bottom returns can be made by removing the knockout
panel in the furnace base. Do NOT remove knock-out
except for a bottom return.
3. Installation of locking-type dampers are recommended in all
branches, or in individual ducts to balance system's air flow.
4. Non-combustible, flexible
recommended for return and supply connections to
furnace.
5. If air return grille is located close to the fan inlet, install at
least one, 90° air turn between fan and inlet grille to reduce
noise.
NOTE: To further reduce noise, install acoustical air turning vanes
and/or line the inside of duct with acoustical material.
Sizing
Existing or new ductwork MUST be sized to handle the correct
amount of airflow for either heating only or heating and air
conditioning.
Insulation
1. Insulate ductwork installed in attics or other areas exposed
to outside temperatures with a minimum of 2" (50.8mm)
insulation and vapor barrier.
2. Insulate ductwork in indoor unconditioned areas with a
minimum of 1" (25.4mm) insulation with indoor type vapor
barrier.
Filters
A Filter must be used:
Filters are not supplied with these furnaces, but can be purchased
from the distributor.
Use either filter type:
•
Washable, high velocity filters are based on a maximum
air flow rating of 600 FPM.
•
Disposable, low velocity filters are based on a maximum
air flow of 300 FPM when used with filter grille.
•
SeeCirculating Air Blower Data for additional data.
NOTE: Disposable, low velocity filters may be replaced with
washable, high velocity filter providing they meet the minimum
size areas. Washable, high velocity filters can be replaced ONLY
with same type and size.
40
B
A
Furnace
Bottom
duct connectors
Specifications are subject to change without notice
Side Mounted Filter Rack
Figure 37
Filter Installation using Optional Filter Rack
When installing or removing a bottom mounted filter, slide the two
side filter clips to the back of the furnace BEFORE installing or
removing. This will allow the filter to clear the front raised edge of
the furnace. Insert filter into side clips first and push filter back until
it is fully engaged into back clip. When filter is in place, slide clips
back into place midway on filter as shown in Figure 38 and
Figure 39.
Bottom Mounted Filter Rack
Figure 38
Center Clip
side-to-side
are
Slide filter clips towards back before removing
Figure 39 Filter Clip Construction
1
1 /
"
2
(38.1)
26 Ga. Galvanized Steel
FAST part number 1008482
Refer to Figure 40 and for guidelines to install filters. Furnaces
which require larger filter media and have limited clearances on
one side of furnace, require a standoff filter rack, see Figure 40,
available from your distributor.
25-20-90
in(mm)
9"
25-24-18-1
(228.6)
in(mm)
(76.2)
3"
1
1 / "
(31.8)
4
11
/ "
(27)
16
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