Rheem air handler in attic came with stock reusable air filter. Well it's been in place for 1+ year and not a spec of dirt on it. Surely its letting everything pass except the occassional rock (just joking). In any case the plastic filter screen frame measures 16" (high) x 21" (wide). I bought a
16x20x1 filter but it doesn't really fit. Too small, leans forward toward coils and not wide enough. I understand that I may need a filter housing. Where can I mail order or purchase such a housing. Rheem has got to have what I need but can't find it.Thanks,
Russ