Size weirdness in furnace filters, need help (relatively fast)

Factual Questions
1

Has anybody run across this?

I have two heat pumps. One takes a 20 x 20 x 1 size filter and the other a 20 x 25 x 1 size. Actually, the size of the slots are 19.5 x 19.5 and 19.5 x 24.5. I have had to use the cheap blue filters, as I never have been able to find the pleated type that is not too big.

I recently had to have the coils in one cleaned, as a lat of gunk had accumulated on them, causing drainage problems when using the A/C.

So, I tried again to check out the better ones at a local building supply store. Taking my rule with me, I picked the 20x20 size first. Right on the label is says “Actual size 19,5 x 19.5.”

However, when I started measuring them, I found they varied, but all where 3/16, 1/4 or 5/16 inches too large. I also found that some had the proper size in the midle of the filter, but were too large on all edges. Same with the larger ones.

What the heck is this? I had that trouble before when I ordered some from Amazon, and had to return them. The only thing I can think of is the things are probably made in China, where they have trouble getting quality control right.

Has anybody found a place where they make filters actually the stated size? I have tried two other places that carry several makes, and they are all the same.

Even the ones only 3/16 too large cannot be forced into the slot, so am back to the cheap filters.

Any a final gripe. Why in the world would the heat pump companies, one Trane and the other American Standard, not make the slots the standard sizes shown?

2

If the filters are too large cut them to size.
A lot of filters have cardboard around the edges. remove the tape or the staples in two corners. Cut the media down to size the cut the cardboard edges to size. REtape and install.

Or
If the filter rails are accessible check to see how they are mounted on the unit. Many are screwed in with self drilling screws. If this is what you have remove the rail and move it to a proper opening and screw back in.

Or it may be possable to bend the rails open just a little.

3

Interessting idea about cutting them down. I’ll try that.

My units have the filter slot at the bottom, and they are just big enough to slide in the filter, unfortunately, so no way can get in to adjust the rails. Other than TNT, that is.

4

You might also consider having custom electrostatic filters made. They are not exceptionally high in filtering ability, but they are good for many years with washing and can be made to exact fit.

They use a dense plastic fiber that gets static charged from the airflow, grabbing and holding dust. They worked very well in my last house. They shouldn’t be more expensive than about a year’s worth of good-quality paper filters.

5

Yeah, well my central air intake is about 16x36. I can buy custom jobs in that size, but they’re 10x the price of a regular one, and I think not even reusable. I get 2 16x20 and cut a total of 4 inches off either/both sides and and tape them together. I’ll have to do that in just a little bit here.

6

There are companies that make filters sized to order. I get emails from a company that makes custom filters sized to the 1/8 of an inch. I’m sure there are other companies out there as well.

8

For me, this is a timely resurrection of a zombie thread. :grin: I am another owner of a ground-linked heat pump with weird sized filters. (23.75 x 35.75 x 0.75, I think.) The local company that installed my heating/AC system has been my source for the nonstandard filters, but now they can’t seem to get it right and are providing me with ones that are too big. I plan to comparison shop both websites mentioned in this thread. (Air Filters Delivered and Filter King).