if constructed and installed in accordance with the latest edition of SMACNA construction standard on fibrous glass ducts. Both acoustical lining and fibrous ductwork shall comply with NFPA 90B as tested by UL Standard 181 for Class 1 Rigid air ducts.
III. SUPPLY AIR CONNECTIONS
A. Upflow Furnaces
Connect
B.Downflow Furnaces
Connect
C.Horizontal Furnaces
Connect
IV. RETURN AIR CONNECTIONS
The furnace and its return air system shall be designed and installed so that negative pressure created by the air circulating fan cannot affect another appliance’s combustion air supply or act to mix products of combustion with circulating air, and that the air circulating fan of the furnace, if installed in an enclosure commu- nicating with another
WARNING: Never connect
V.FILTER ARRANGEMENT
→CAUTION: Never operate a unit without a filter or with
filter access door removed. Failure to follow this caution will result in minor unit operation or performance satis- faction.
CAUTION: Use care when cutting support rods in filters to protect against flying pieces and sharp rod ends. Wear safety glasses, gloves, and appropriate protective cloth- ing. Failure to follow this caution could result in minor personal injury.
→CAUTION: For airflow requirements above 1800 CFM, see Air Delivery table in Product Data literature for specific use of single side inlets. The use of both side
inlets, a combination of 1 side and the bottom, or the bottom only will ensure adequate return air openings for airflow requirements above 1800 CFM. Failure to follow this caution will result in minor unit operation or perfor- mance satisfaction.
NOTE: Side
A.Upflow Furnaces
Fig. 23—Filter Installed for Side Inlet
A00217
The
B.Downflow and Horizontal Furnaces
The
NOTE: Remove and discard bottom closure panel when bottom inlet is used.
TABLE 2—FILTER INFORMATION
FURNACE | FILTER SIZE (IN.) |
| FILTER TYPE | ||
CASING |
|
|
| ||
Side Return | Bottom Return | FRAMED | |||
WIDTH (IN.) | |||||
| |||||
(1) 16 X 25 X 1† | (1) 16 X 25 | X 1 | Cleanable | ||
21 | (1) 16 X 25 X 1* | (1) 20 X 25 | X 1† | Cleanable | |
(1 or 2) 16 X 25 X 1* | (1) 24 X 25 | X 1† | Cleanable | ||
|
|
|
|
|
*Filters can be field modified by cutting frame as marked and folding to desired size. Alternate sizes can be ordered from your distributor or dealer.
†