Installation; Upflow Installation; Bottom Return Air Inlet; Side Return Air Inlet - Carrier 58CTA Installation And Service Instructions Manual

If:
I = combined input of all other than fan-assisted appli-
other
ances in Btu/hr
I = combined input of all fan-assisted appliances in Btu/hr
fan
ACH = air changes per hour (ACH shall not exceed 0.60.)
→
The following requirements apply to the Standard Method and to
the Known Air Infiltration Rate Method.
1. Adjoining rooms can be considered part of a space if:
a. There are no closable doors between rooms.
b. Combining spaces on same floor level. Each opening shall
have free area of at least 1 in.
of the total input rating of all gas appliances in the space,
but not less than 100 in.
commence within 12" (300 mm) of the ceiling and the
second opening shall commence within 12" (300 mm) of
the floor. The minimum dimension of air openings shall be
at least 3 in. (80 mm). (See Fig. 8.)
c. Combining space on different floor levels. The volumes of
spaces on different floor levels shall be considered as
communicating spaces if connected by one or more perma-
nent openings in doors or floors having free area of at least
2
2 in. /1,000 Btuh (4,400 mm
all gas appliances.
2. An attic or crawlspace may be considered a space that freely
communicates with the outdoors provided there are adequate
permanent ventilation openings directly to outdoors having
free area of at least 1-in.
all gas appliances in the space.
3. In spaces that use the Indoor Combustion Air Method,
infiltration should be adequate to provide air for combustion,
permanent ventilation and dilution of flue gases. However, in
buildings with unusually tight construction, additional air
MUST be provided using the methods described in the
Outdoor Combustion Air Method section.
Unusually tight construction is defined as
Construction with:
a. Walls and ceilings exposed to the outdoors have a continu-
ous, sealed vapor barrier. Openings are gasketed or sealed
and
b. Doors and openable windows are weatherstripped and
c. Other openings are caulked or sealed. These include joints
around window and door frames, between sole plates and
floors, between wall-ceiling joints, between wall panels, at
penetrations for plumbing, electrical and gas lines, etc.
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Combination of Indoor and Outdoor Air
1. Indoor openings shall compy with the Indoor Combustion
Air Method below and,
2. Outdoor openings shall be located as required in the Outdoor
Combustion Air Method mentioned previously and,
3. Outdoor openings shall be sized as follows:
a. Calculate the Ratio of all Indoor Space volume divided by
required volume for Indoor Combustion Air Method
below.
b. Outdoor opening size reduction Factor is 1 minus the
Ratio in a. above.
c. Minimum size of Outdoor openings shall be the size
required in Outdoor Combustion Air Method above
multiplied by reduction Factor in b. above. The minimum
dimension of air openings shall be not less than 3 in. (80
mm).
2
/1,000 Btuh (2,000 mm
2 2
(0.06 m ). One opening shall
2
/kW) of total input rating of
2
/4,000 Btuh of total input rating for
2
/kW)
Fig. 9—Removing Bottom Closure Panel

UPFLOW INSTALLATION

Bottom Return Air Inlet

These furnaces are shipped with bottom closure panel installed in
bottom return-air opening. Remove and discard this panel when
bottom return air is used. To remove bottom closure panel,
perform the following:
1. Tilt or raise furnace and remove 2 screws holding bottom filler
panel. (See Fig. 9.)
2. Rotate bottom filler panel downward to release holding tabs.
3. Remove bottom closure panel.
4. Reinstall bottom filler panel and screws.

Side Return Air Inlet

These furnaces are shipped with bottom closure panel installed in
bottom return-air opening. This panel MUST be in place when
only side return air is used.
NOTE: Side return-air openings can be used in UPFLOW and
most HORIZONTAL configurations. Do not use side return-air
openings in DOWNFLOW configuration.

Leveling Legs (If Desired)

In upflow position with side return inlet(s), leveling legs may be
used. (See Fig. 10.) Install field-supplied, 5/16 X 1-1/2 in. (max)
corrosion-resistant machine bolts, washers and nuts.
NOTE: Bottom closure must be used when leveling legs are used.
It may be necessary to remove and reinstall bottom closure panel
to install leveling legs. To remove bottom closure panel, see item
1 in Bottom Return Air Inlet section in Step 1 above.
To install leveling legs:
1. Position furnace on its back. Locate and drill a hole in each
bottom corner of furnace. (See Fig. 10.)
2. For each leg, install nut on bolt and then install bolt and nut in
hole. (Install flat washer if desired.)
3. Install another nut on other side of furnace base. (Install flat
washer if desired.)
4. Adjust outside nut to provide desired height, and tighten inside
nut to secure arrangement.
5. Reinstall bottom closure panel if removed.
10

INSTALLATION

A02098