The DVAG25-DF Direct Vent Wall Heater from Ashley Hearth Products makes the perfect solution for zoned heating. The space-saving direct vent furnace design mounts to an exterior wall, and the adjustable vent assembly fits walls from 4-1/2 inches to 10 inches thick. For clean, comfortable heat when and where you want it, the gas flame is completely sealed inside, away from all contact with room air. Air necessary for combustion is drawn into the chamber from outside through the vent, and combustion products are vented directly to the outside. Only clean, gentle heat in continuous circulation is delivered into the room. Windows and doors stay closed because no room air is used for combustion. The DVAG25-DF direct vent dual fuel wall furnace is designed to heat up to 825 Sq. Ft., with a 25,000 BTU input.