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  1. #1
    Join Date
    Jun 2013
    Northern Virginia

    Why manufacturers make air handlers this way?

    Hey folks I got a question for you: if we have let's say a 5 ton air handler, with rule of thumb requirement for return air filter area of 200sq in/ton, give or take, why manufacturers make a spot for a 22x22x1 filter in the air handler/ furnace? It is so undersized, especially if people use pleated filters. And no notes in installation manuals about increasing filter area/proper calculations. I work for a big company, they have couple of dozens stores and every single 4 or 5 ton system either has filter in the AH or has just single 20x20x1 filter rack. Filters get plugged real fast, and then of course "No AC" call.
    Also if anybody knows good online store to get all duct parts(take-offs, ceiling grills and especially ceiling return boxes - I can't find them!!!) i'd really appreciate info. If links are not permitted, please send me a PM.

  2. #2
    Join Date
    Mar 2007
    Myrtle Beach, SC
    Usually the filter in the unit is only for closet installs. Then there is no return duct, so all of the static is available for the supply duct system.

    Still I would not use a pleat in there.

    If there is a return duct, you should use a filter grille or put a larger filter rack in the return duct.
    Remember, Air Conditioning begins with AIR.

  3. #3
    Join Date
    Nov 2011
    The mfg's provide the blower performance data. Sizing the filters and ductwork isn't their problem.

  4. #4
    Join Date
    Oct 2002
    More and more manufactures are not including the filter slot.

  5. #5
    Join Date
    Nov 2007
    Can you raise air handlers and install 2" filter racks? 2" filters have more surface area than 1" filters. Correct me if I'm wrong on this.

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