My mother’s AC system has Rheem RBHA-14A00NFAA air handlers. The filter is a 12.75x21x1 washable type. Those don’t appear to be very effective and I can’t even seem to find replacement ones to buy.
I did find these:
Accumulair Gold 12.75x21x1 (Actual Size) MERV 8 Air Filter/Furnace Filters. Will these work OK?
The unit is in a 4′ crawl space that is not easy to get to (AC retrofit into old house a long time ago), so it involves a lot of squatting, ducking, crawling, etc to get to the filter. My thought is that it will be much easier to just go down with a new filter, swap, discard the old.. rather than go down, take out the filter, crawl out, wash it, crawl back in to install it.