Running HVAC without filters?
I recently bought a 4 unit multifamily. When going through with the home inspector I saw the furnaces did not have any filters in them. It was warmer at the time and since they were not being run I did not think too much about it. Went to the building shortly after closing and saw they were running without filters. I have always learned that the furnaces need to be run with filters and I did go out and buy some for the furnaces. All the furnaces are new due to the old ones being damaged beyond repair due to a flood. While I plan to use filters I was just curious does anyone run their furnaces without filters? What kind of harm could happen as a result?
Thanks