Filtering heat/air unit
We are currently hanging out at our old farm house which has an outside combo heat/air unit; the heat part is propane. The filter is currently inside the unit, which is outside; our return air is in the floor inside. My brother has the same situation at his house, but he filters his with a thich, washable filter at his return air inside. Could I do that too? It would be much easier, especially when it was cold and snowy outside.