Installation on Combustible Flooring
(Using an Additive Base)
1 − When unit is installed on a combustible floor, an addi-
tive base must be installed between the furnace and
the floor. The base must be ordered separately. See table 2 for opening size to cut in floor.
CAUTION
The furnace and additive base shall not be installed directly on carpeting, tile, or other combustible ma- terial other than wood flooring.
TABLE 2
ADDITIVE BASE FLOOR OPENING SIZE
Cabinet | Catalog | Front to Rear | Side to Side | |||
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Width | Number | in. | mm | in. | mm | |
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B Cabinet | 11M60 | 22 | 559 | 18 − 3/4 | 476 | |
(17.5") | ||||||
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C Cabinet | 11M61 | 22 | 559 | 22 − 3/4 | 578 | |
(21") | ||||||
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D Cabinet | 11M62 | 22 | 559 | 25 − 3/4 | 654 | |
(24.5") | ||||||
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2 − After opening is cut, set additive base into opening.
3 − Check fiberglass strips on additive base to make sure they are properly glued and positioned.
4 − Lower supply air plenum into additive base until ple- num flanges seal against fiberglass strips.
NOTE − Be careful not to damage fiberglass strips. Check for a tight seal.
5 − Set the furnace over the plenum.
6 − Ensure that the seal between the furnace and plenum is adequate.
Installation on Cooling Coil Cabinet
1 − Refer to reverse−flow coil installation instructions for correctly sized opening in floor and installation of cabi- net.
2 − When cooling cabinet is in place, set and secure the furnace according to the instructions that are provided with the cooling coil. Secure the furnace to the cabinet.
3 − Seal the cabinet and check for air leaks.
Return Air Opening −− Downflow Units
Return air may be brought in only through the top opening of a furnace installed in the downflow position.The follow- ing steps should be taken when installing plenum:
1 − Bottom edge of plenum should be flanged with a hemmed edge (See figure 15 or 16).
2 − Sealing strips should be used to ensure an airtight seal between the cabinet and the plenum.
3 − In all cases, plenum should be secured to top of fur- nace using sheet metal screws.
4 − Make certain that an adequate seal is made.
PLENUM
(Field Provided) 
SECURE FROM OUTSIDE CABINET
SEALING STRIP | CABINET | |
SIDE PANEL | ||
(Field Provided) | ||
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Side View
FIGURE 15
G61MP UNIT
PROPERLY
SIZED FLOOR
OPENING
SUPPLY AIR PLENUM
ADDITIVE BASE
PLENUM
(Field Provided)
SECURE FROM |
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INSIDE CABINET | Side View |
SEALING STRIP (Field Provided)
CABINET
SIDE PANEL
FIGURE 16
FIGURE 14
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