The Ashley 17.25 in. Propane Gas Direct-Vent Heater makes the perfect solution for zoned heating. With a space-saving direct-vent furnace design, the wall heater mounts to an exterior wall. An adjustable vent assembly on the unit adjusts to fit walls from 4-1/2 in. to 10 in. thick. For clean, comfortable heat when and where you want it, the gas flame is completely sealed inside the vented propane heater, away from all contact with room air.