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  1. #1

    Return air grill with filters

    I have a split system (2 units) with return air grills in the ceilings about 18 X 31" and can't find replacement grills with filters. Please steer me in the right direction. I'm trying to keep my return air ducts clean, and the down draft furnace filters need help. Thank you guys....John in Phoenix, Az

  2. #2
    Join Date
    Aug 2002
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Filter grilles are usually even number sizes,are these grilles intended to have a filter??

    Adding filters at the grilles to one at the equipment can easily restrict air flow,even to the point of damaging the equipment,so be careful.A Pro can test the Static (resistance to air flow),and advise you on adding filters ,or better filters.

  3. #3
    Join Date
    Oct 2007
    It sounds like you want filters in the grilles and at the units. Like Dash said, it is a very bad idea. If you are worried about the ducts then buy some filter grilles and remove the ones at the units. Buy pleated filters not the fiberglass ones. They have much better preformance.

  4. #4

    Thank you

    For the speedy response. I was attempting to filter my entire system at the start of the duct work, thus keeping ALL the ducts as clean as possible. Discovering that a second filter would have that much determint to overall performance is surprising to me.
    I guess I'll leave well enough alone.

    Thank again!

  5. #5
    Join Date
    Dec 2006
    You can still filter at the grilles, it is just not recommended to do both unless you have someone take pressure readings and verify that it is ok. Or you could get rid of the filter at the unit and use filter grilles. Make sure you have enough return air grille capacity since that is a common item done wrong.

  6. #6

    source for grills

    Do I need to have these input ceiling grills made special, or are there off the shelf standard sizes. Mine are kind of non-standard (I think) 17.5" X 31.5".
    Any suggestions for a place that carries a good selection of these ceiling grills with filters?
    Once again thank you guys. Very helpful..........

  7. #7
    Join Date
    May 2007
    DC Metro Area (MD)
    You can have custom filter sizes made. But, how you're going to mount the filters in a grill that is not meant to have filters mounted in it is another question. As others have said, it's not a good idea to have your air "double-filtered" so to speak.

  8. #8

    Not double filtering

    I'll remove the filters in each unit inside the furnance and then use the flip down filter housing, where I can keep a closer eye on the filters and change easily.

  9. #9
    Join Date
    Dec 2002
    Quote Originally Posted by sailorman524 View Post
    I'll remove the filters in each unit inside the furnance and then use the flip down filter housing, where I can keep a closer eye on the filters and change easily.
    my guess would be your measuring the grill outside dimension and that you have a 16" x 30" return air can ( a common size). Give your service contractor a call and he can fix you up.

  10. #10
    Virtually any filter can be manufactured to within 1/8" (plus or minus) , this represents approximately the thickness of the cardboard.

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