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Heating, Air Conditioning, Fridge, HVAC/Placement of AC filter at return grille in wall.

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Filter
Filter  
 Return air grillE
Return air grillE  
QUESTION: Hi Marcus   i   Recently  purchased  A condo and wanted to replace the existing hog air filter with a pleated one from Home Depot or Lowe's. I am attaching  two photos of the exterior grille on the wall and inside the grille.  I called Trane for the correct size and they said it's 20 x 25 by one. The inside of the lip behind the grill is 24 inches.    Therefore, when I try setting inside the lip,  it will not go without forcing it.   I tried placing the filter there and I had to bend it slightly to get it to fit. However when the AC runs I can hear it moving around.     I thought maybe I should buy the 24 inch in length filter, but I don't know if it will completely cover the duct. I then placed the filter up against the duct (I'm assuming it's a duct, it's about 6 to 8 inches inside  the return grille when I open it).  When I place the filter at this location, when the AC runs there is no noise behind the AC return because the filter does not move. So my question is, where is the proper placement  of the AC filter at this location?   Should it be right inside the lip of the grill in which case I'd have to try the 24 inch in length filter or is it OK to place it up against the duct?  One last thing, the dimensions of the games that don' One last thing,  The length of the duct is 24 1/2 inches, but right inside the lip of the return grill is about 24 1/8 inches.  I think that's why am having such a difficult time  fitting it  inside the lip.   Thank you so much for your time. Ali

ANSWER: Ali,
    20 x 25 x 1 return filter is a pretty common size . The filter is designed to fit on the inside lip if the return grill behind hinged door when opened . Often it is not a perfect fit - the return grill may have been damaged on install or it is slightly out of square - you may hear the filter being slightly pulled in when the unit starts - this is ok as long as the opening of the return grill remains covered by the filter . I definitely would not place in the return duct work . If it really bothers you , a custom permanent aluminum framed filter can be ordered to your exact dimensions. Here is a place for example http://www.airfilterusa.com/residential/washable-furnace-filters . Hope this helps

         Marcus  Air Zero

---------- FOLLOW-UP ----------

QUESTION: Thanks so much for your prompt response.  Is it o.k. if you slightly bend the frame to get it to fit?  Also,  curious as to  why would you not place it against the duct?  It covers the duct completely.

Answer
Ali,
    Yes it is ok to slightly bend to get into frame . If the filter sits in the frame correctly and is covering the entire opening of the return duct it has the same effect as placing it against the duct . If you wanted you could place at opening of duct , just not in duct work.  

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Marcus HVAC / Air Conditioning Expert

Expertise

Any residential/commercial air conditioning questions . Commercial refrigeration and commercial ice machine questions . No appliance questions please .

Experience

20 plus years in the industry . State licensed HVAC contractor .

Organizations
Air Conditioning Contractors of America ,Refrigeration and Air Conditioning Contractors Association Inc.

Education/Credentials
2 year trade school . 100's of hours of manufacturers specific school . 20 plus years in real world experience .

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