I have 3 AC Filters, two 20x30x1 upstairs, and a smaller 10x20x1 downstairs,
the filter downstairs fits perfectly, one of the upstairs fits a little tight some bending required, and the other fits extremely tight.
I noticed a screw was installed at a extreme angle causing less clearance for the filter, I removed it but before I reinstall it I'm guessing I need to patch the hole with mastic? (Pictured)
I also noticed another screw hole above the duct that should probably be patched? (Pictured) I can't imagine air getting sucked from the attic full of fiberglass insulation past the filter can be a good thing. Although I can't see behind it, if there is some other material behind it or how deep it goes.
Is there any adjustment on these filter housings? I did noticed they installed the screws much higher on the filter housing downstairs and that filter fits perfect, I believe the screw heads are causing my issues, maybe switching to screws with flat heads will do the trick.
The House was constructed in 2005.
Photos of two filters, 3M Ultra Allergen Purple, the one thats bent more was installed with the screw, the second clean one was installed with the screw removed. (A little more space but still required some bending and damage to the cardboard).
Screw removed installed at extreme angle, above another random screw hole
Screw Installed Correct and Flush