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Custom Air Filters For Your Home

Custom Air Filters For Your Home
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Sharon Asked:

For reasons unknown to me, the builder of my 1,700 sq foot house custom filter sizes for houseinstalled a 32″ x 25″ x 1″ return vent where my air filter goes.  No one (that I can find) makes a 32 x 25 filter.

I had been using two 16 x 25s taped together down the middle, but Arm & Hammer stopped making them.  Those fit perfectly.  Now all I can find are 16 x25s that are really 15-1/2 x 24-1/2 and when taped together they still leave about an inch gap total on either side.

My ACTUAL filter size needs to be 32 x 25 to fit properly.  Is there anything I can do to make the intake cover a bit smaller?  Right now, all I can do is tape the filters together with a nearly 1-inch gap in between and tape really, really well.

I am currently using DuPont Platinum Merv 12 filters (they used to be 15-3/4 but are now 15-1/2 in actual size).  Custom filters don’t seem to be an option, because the sites I have found that make them also simply tape two 16s together.  This is getting really frustrating, so HELP!!  Thanks in advance.

The Problem With Common and Odd Filter Sizes

This is a very common problem. Even standard sized filters often don’t fit properly. There is just too much size discrepancy between the manufacturers of air conditioning and heating equipment.

Filter manufacturers are trying to provide a product that will fit most common applications and to do this they have to undersize the filters a bit in an attempt to compensate for these discrepancies.

The Solution to This Problem

Unfortunately this causes many problems also. The only  place to get exact custom sized filters that I am aware of is at this site. Below is a excerpt from their page.

EXACT MEASUREMENT: Furnace and Air Conditioner Filters have an actual size that is a  fraction of an inch smaller in length and width than the listed air filter size (for example, a 20x30x1 air filter is actually 19 ½ x 29 ½ x ¾ ). Please use the actual size of your current air filter when ordering custom sizes. Use a tape measure or yardstick if necessary to measure the outer dimensions for your custom air filter order.

There is a form where you input the size that you need which accepts measurements down to 1/16 of an inch. They are looking for the actual size that you need. Add the required information in all of the fields and you are given a price before you buy.



P.S. There is another option that works well sometimes. You can have a piece of sheet metal cut and bent in a pleated shape. This will fill the space left between filters or at the edge. Have it cut to the length you require and folded in a pleated shape along the length to the width required. Use lite gauge sheet metal or aluminum so the width can be adjusted. The disadvantage of this is that it can negatively impact air flow in some cases. The best solution is to use filters that fit properly.

About the author: Don has been working in the HVAC industry for more than 25 years and shares his experience and knowledge on this site. If you find the information presented here helpful please share with your friends.

{ 2 comments… add one }

  • There’s no reason why you can’t just replace the current access door/filter holder with one of the standard sizes (e.g., 24×30 or 25×30) — or install a piece of sheet metal as Don describes above. This will allow you to use a standard filter which is nominally ’24×30′ or ’25×30′ (although slightly smaller in reality).

    The difference in air flow will be minimal, and using standard sized filters will be less expensive.

  • DonaldT

    If your return grill is already undersized, replacing it with a smaller one may not be a good idea. You should have a contractor check it to ensure installing a standard size (smaller) return grill will not cause air flow problems.

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