58SC0B/58SC1B: Installation, Start–Up, Operating and Service and Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
9
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.
2
/4,000 BTUh of total input rating for 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.
4. Unusually tight construction is defined as construction with:
a. Walls and ceilings exposed to the outdoors have a continuous,
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.
Combination of Indoor and Outdoor Air
1. Indoor openings shall comply 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).
INSTALLATION
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 two 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.
A10273
Fig. 9 – Removing Bottom Closure Panel
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. (8 x 38 mm) (max)
corrosion-resistant machine bolts, washers and nuts.
A89014
Fig. 10 – Leveling Legs
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.
To install leveling legs:
1. Position furnace on its back. Locate and drill a hole in each bottom
corner of furnace (see Fig. 10).
Table 3 – Minimum Space Volumes for 100% Combustion, Ventilation, and Dilution from Indoors
ACH
*
*. Air Changes/Hour
OTHER THAN FAN-ASSISTED TOTAL
(1,000’S BTUH GAS INPUT RATE
FAN-ASSISTED TOTAL
(1,000’S BTUH GAS INPUT RATE)
30 40 50 44 66 88 110 132
Space Volume (ft.
3
)
0.60 1,050 1,400 1,750 1,100 1,650 2,200 2,750 3,300
0.50 1,260 1,680 2,100 1,320 1,980 2,640 3,300 3,960
0.40 1,575 2,100 2,625 1,650 2,475 3,300 4,125 4,950
0.30 2,100 2,800 3,500 2,200 3,300 4,400 5,500 6,600
0.20 3,150 4,200 5,250 3,300 4,950 6,600 8,250 9,900
0.10 6,300 8,400 10,500 6,600 9,900 13,200 16,500 19,800
0.00 NP NP NP NP NP NP NP NP
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