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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 bot-
tom filler panel. (See Fig. 9)
Bottom
Closure Panel
Bottom Filler Panel
Fig. 9 - - Removing Bottom Closure Panel
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. (8 x 38
mm) (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.
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.
5/ 16
(8mm)
(44mm)
DOWNFLOW INSTALLATION
A10273
NOTE: For downflow applications, this furnace is approved for
use on combustible flooring when any one of the following 3
accessories are used:
Downflow combustible floor subbase
S
S
Manufacturer's approved Cased Coil or Coil Casing
1. Determine application being installed from Table 4.
2. Construct hole in floor per Table 4 and Fig. 11.
3. Construct plenum to dimensions specified in Table 4 and
Fig. 11.
4. If downflow subbase is used, install as shown in Fig. 12. If
Coil or Coil Casing, install as shown in Fig. 13.
NOTE: It is required that the perforated supply- -air duct flanges
be completely folded over or removed from furnace when
installing the furnace on a factory- -supplied cased coil or coil box.
To remove the supply- -air duct flange, use wide duct pliers or
hand seamers to bend flange back and forth until it breaks off. Be
careful of sharp edges. (See Fig. 14)
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 bot-
tom filler panel. (See Fig. 9)
2. Rotate bottom filler panel downward to release holding
tabs.
3. Remove bottom closure panel.
9
(8mm)
5/ 16
1
3
/
4
1
3
/
4
(44mm)
(8mm)
5
/
16
(8mm)
5/ 16
(44mm)
1
3/ 4
1
3/ 4
(44mm)
Fig. 10 - - Leveling Legs
A89014
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