Recent content by flipper

I ended up cutting out both sides and putting two 14x20 filters in.

Here is my issue. I have an older but never used furnace I'm putting in my garage. The instructions say I need to put in at least a 16x25 external filter. I can only cut an opening of 15x19. So do I cut out both sides of the furnace and put (2) 14x20s filters in?