Originally Posted by garywinder
I just moved into a 1970 house where the previous owner installed a new furnace which has a filter size of 20x12x1...the problem is the existing return vent is 16x12x1 so where the two meet there is a 4" hole with no filter. Is there something I can put in between that reduces the new return to the old one? And maybe even install a 5" filter instead of the 1"?
have the system checked and sized for proper filter size before you do anything....need right air flow amount....