WARNING
Improper installation of the furnace can result in per- sonal injury or death. Combustion and flue products must never be allowed to enter the return air system or air in the living space. Use sheet metal screws and joint tape to seal return air system to furnace.
In platform installations with furnace return, the fur- nace should be sealed airtight to the return air ple- num. A door must never be used as a portion of the return air duct system. The base must provide a stable support and an airtight seal to the furnace. Al- low absolutely no sagging, cracks, gaps, etc.
For no reason should return and supply air duct sys- tems ever be connected to or from other heating de- vices such as a fireplace or stove, etc. Fire, explo- sion, carbon monoxide poisoning, personal injury and/or property damage could result.
The unit may be installed three ways in downflow applica- tions: on non−combustible flooring, on combustible flooring using an additive base, or on a reverse−flow cooling coil cabinet. Do not drag the unit across the floor in the downflow position. Floor and furnace flange damage will result.
Refer to figure 11 for clearances in downflow applica- tions.
Installation on Non−Combustible Flooring Figure 12
1 − Cut floor opening keeping in mind clearances listed on unit rating plate. Also keep in mind gas supply connec- tions, electrical supply, flue and air intake connections and sufficient installation and servicing clearances. See table 1 for correct floor opening size.
2 − Flange warm air plenum and lower the plenum into the opening.
3 − Set the unit over the plenum and seal the plenum to the unit.
4 − Ensure that the seal is adequate.
TABLE 1
NON−COMBUSTIBLE FLOOR OPENING SIZE
| Front to Rear | Side to Side | |||
Cabinet Width |
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in. | mm | in. | mm | ||
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B Cabinet (17.5") | 19 − 3/4 | 502 | 16 − 5/8 | 422 | |
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C Cabinet (21") | 19 − 3/4 | 502 | 20−1/8 | 511 | |
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NOTE − Floor opening dimensions listed are 1/4 inch (6 mm) larger than the unit opening. See dimension drawing on page 2.
Downflow Application Installation Clearances
| Top |
Left Side | Right Side |
FURNACE
PROPERLY SIZED FLOOR OPENING
SUPPLY AIR
PLENUM
| Bottom | |
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Top |
| 0 |
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*Front |
| 0 |
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Back |
| 0 |
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Sides |
| 0† |
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Vent |
| 0 |
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Floor |
| NC‡ |
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*Front clearance in alcove installation must be 24 in. (610 mm). Maintain a minimum of 24 in. (610 mm) for front service access. †Allow proper clearances to accommodate condensate trap and vent pipe installation.
‡The furnace may be installed on a combustible wood floor if an op- tional additive base is installed between the furnace and the com- bustible floor.
FIGURE 11
FIGURE 12
Installation on Combustible Flooring Figure 13
1 − When unit is installed on a combustible floor, a down- flow combustible flooring base must be installed be- tween the furnace and the floor. The base must be or- dered separately. See table 2 for opening size to cut in floor.
CAUTION
The furnace and combustible flooring base shall not be installed directly on carpeting, tile, or other com- bustible material other than wood flooring.
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