International comfort products C9MVX Installation Instructions Manual page 40

Connections
NOTE: Return air can enter through either side, both sides, the
bottom or a side and the bottom. Return air can not enter through
rear of the furnace. When the furnace is located in an area near or
adjacent to the living area, the system should be carefully designed
with returns to minimize noise transmission through the return
grille. Any blower moving a high volume of air will produce audible
noise which could be objectionable to when the unit is located very
close to living areas. It is advisable to route the return air ducts
under the floor or through the attic.
1. For side connections using a 16" x 25" (406.4 x 635mm)
filter, cut out the embossed area shown in Figure 36. This
1
will provide a 14 /
approximate opening.
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,
recommended for return and supply connections to
furnace.
Figure 36
Side Return Air Cutout
1 " (368.3mm) Height of Cutout for 16" x 25" (406.4 x 635mm) Filter
A = 14 /
2
" (571.5mm) Width of Cutout for 16" x 25" (406.4 x 635mm) Filter
1
B = 22 /
2
Embossed Area
on Side of Furnace
NOTE: Furnaces with 5 TONS cooling rating may require two(2)
side returns or one side return with bottom return.
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 supplied with these furnaces, and additional filters may
be purchased from your 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.
•
See Technical Manual, Circulation Air Blower Data for
additional data.
40
1
" x 22 / " (368.3 x 571.5mm)
2 2
flexible duct connectors
B
A
Furnace
Bottom
Specifications are subject to change without notice.
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.
Figure 37
are
Filter Installation using 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 or
Figure 39.
Figure 38
Center Clip
side-to-side
9" (152.4mm)
Slide filter clips towards back before removing
Figure 39
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.
NOTE: If filters are only suitable for heating application,
advise homeowner that filter size may need to be increased if
air conditioning is added.
Side Mounted Filter Rack
25-20-90
Bottom Mounted Filter Rack
Filter Clip Construction
3" (76.2)
1
25-24-18-1
1 (31.8)
/ "
4
11
/ "
(27)
16
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