What types of vent-free heating appliances are available?
Small portable units for use in a single room are manufactured for emergency heating–others are made to serve as a permanent heat source. Optional blower kits and ductwork allow them to heat two or more rooms. Available styles include cabinet mounted units, wall mounted units, fireplaces, and fireplace inserts with a variety of flame patterns including blue flame, infrared, yellow flame, and glowing logs. Sizes range from under 5,000 Btu/hour to over 38,000 Btu/hour. How efficient are direct vent heating appliances? While the flame burns with over 99 percent efficiency not all the heat is available. Approximately 9.6 percent of the heating energy available in gas comes from burning the hydrogen which produces water vapor. To recover this heat, the water must be condensed. With an unvented heater, the water vapor condenses on room surfaces, which increases the potential for wood rot, peeling paint, plaster failure, and mold growth. To prevent wet windows and walls, the vapor must be pr
