Furnace filters

[Eigenvector]

So I was gonna replace my gas furnace filter today before the cold weather starts, or at least the cold night weather. But for the life of me I can't find any information on or about my gas furnace - except for the brand and the date of installation. Heck, even the filter is one of those freeform washable filters that doesn't have a cardboard border with the dimensions on it (basically just a rectangular mat of green fibers that is totally impregnated with dust and looks about a useful as a third tit). So I took it out and measured it - it comes out to be 14x27

So I go out looking for a filter for it and no one I know of sells anything even remotely like that size, 14x30 14x24 14x25 but not 14x27.

So anyway I have a Payne furnace installed in 1983, there is a wiring diagram on the inside of the filter cover and that give a model number of

397H or 375A but that's it. There's nothing on the outside of the furnace and nothing that I could see on the inside where the motor and burners sit.

So what's the story, the Payne homepage is about a useful as a 4th tit and I couldn't pull anything up about a 375 or 397.

[redwoodcoast]

[PaPaPeng]

Perhaps get the next size down standard filter and make a cardboard frame to fit from box cardboard.

[wayne]

[George E. Cawthon]

The filter doesn't have to fit flat, in fact, many filters have a / installation with an angle of

20- 70 degrees others have a /\\ installation. Actually, the steeper the angle the more air flow and filtering surface. So, if you can put it in at an angle, a 14 x 30 should work. If it has to be flat just cut 3 inches off and tape the end with whatever type of tape you want to use.

[Jim]

[Eigenvector]

Yeah but the thing that bothers me is that NONE of the filter sites let you search by FURNACE - which would be more helpful.

[Robert Gammon]

Measure the rack that holds the filter, not the filter itself. It should be a shade more than one of the numbers you found at Filters Now

[Eigenvector]

Thank you that's the best information I've managed to glean from here and alt.hvac.

[Eigenvector]

Well so I measured the rack size, 13x23" Not exactly what I had hoped for, but that's what the dimensions work out to.

So I decided to cram a 14x24 in there until I can figure something out. I tried a 12x24 and that was way too skinny, so skinny it wasn't wide enough to be held by the filter supports. I ought to take a pic of it, because I swear it should be 14x27 but there is a retaining loop that cuts into the filter rack.

I would have totally thought that residential furnace filters would be standard sizes.