The previous owners of my house had some kind of gas fireplace or propane heater or something. They vented through the living room wall to the deck. When they removed it, they covered the interior wall hole with paneling and left the exterior hole in place, with the vent cover, stuffed full with bathroom towels. What's the appropriate fix for this? My first thought is to fill the hole with insulation and replace the vinyl siding to cover it. Should I do more?