Furnace filter question - the way this was done seems very wrong

(See pic). I’m not home to take a better pic, but the filter is laying flat where my artwork indicates, but is held in place by gravity alone, no clamp. The hole is about 18 by 20 and the outer frame (no clamps) has room for a 24 by 22

It’s been this way for years, the house is newish to me, but the overall system dates to 2001/2009. Is this a little crazy?


p.s. I’ve had lots of questions lately. I try to split into different posts when the topics are different. So, several posts. Thanks to all who have helped, specially @pjmax. (Who needs to sleep more!)

 

crazy having a filter on the bottom of an up flow furnace?

What may be crazy is if that is a dryer duct being used for the furnace flu pipe?

 

Good point, I didn’t even think of that. It’s been like that since I had the house. The home inspector didn’t say anything, and there were a couple tech visits along the way too. It’s the semi rigid vent type.

for the filter, it’s the total lack of any form of holding it In place that seems odd. If I had better filters I’m sure they’d bounce about

 

Have you looked at a manual?
In the one I saw there was a spring/cable (I think) that ran across the center of the filter to hold it down.
Look like it would be easy to adda couple angle irons on the sides to hold it down.

 

Thanks @manden.

I'll definitely be finding some way to clamp it down. I was more surprised to see that somebody somewhere in the past made it the way they did.

I found a handful of pictures and manuals, most of them had a (roughly) "U" shape, the furnace/evaporator on one of the verticals, the air return on the other, and the filter vertical, and held in place firmly in the little crossbar (the bottom of the U) between the two sides. Thanks all for the thoughts