move heat into the room. Inserts can fit into almost any existing fireplace and come in a wide array of styles and sizes. Vented models come in an airtight metal cabinet with sealed glass doors. They sometimes require a chimney liner to ensure proper venting. Some models have a two-pipe system -- one brings in air for the burner, the other sends out the combustion byproducts. Unvented models do not require sealed glass doors - - all of the heat produced goes into the room. All units can be controlled by a switch, remote control or ther- mostat.
Purchase price and installation for inserts vary, depending on the style and installation requirements. If neces- sary, you can add adjustable panels or "surrounds" to fill in any space between the insert and the original fire- place.
Gas Fireplaces
Gas fireplaces are complete, prefabricated units that come in a huge variety of sizes and styles, including see- through, three-sided and traditional fireplace configurations. The size of the firebox -- the interior where the fire burns -- varies from 32 to 45 inches in width. The fireplace can be placed along inside or outside walls, under windows, as a peninsula between rooms, in bookcases and media centers, in corners or wherever else you’d like a fireplace. These units can be vented up through the roof or through a side wall, or can be unvented. Some models use a fan or blower to help move the combustion byproducts outdoors or to circulate warm air from the fire into the room. Because no masonry work is needed, natural gas fireplaces are economical to install.
All gas fireplaces feature realistic gas logs with burning flames and some can be used as supplemental heat. Gas fireplaces that are classified as "decorative" appliances are generally low-efficiency units that are designed primarily for their appearance and the radiant heat they provide to a room. They usually don’t have efficiency ratings.
Fireplaces that are classified as space heaters are given efficiency ratings like furnaces and other types of space heaters. The standard is the Annual Fuel Utilization Efficiency or AFUE rating. The AFUE for a fireplace takes into consideration the energy used while the fireplace is operating, any energy lost in start-up and shut down, and any fuel used in a standing pilot light. AFUEs for vented gas fireplaces or gas stoves are in the 70 to 80 percent range.
These units contain a heat exchanger -- a metal box used to transfer heat from the burner to the air to be circu- lated -- and a blower or fan to move the warmed air through the room, usually through a decorative grill on the front of the fireplace.
Gas Stoves
Gas stoves are good substitutes for more polluting wood-burning stoves. These free-standing units come in traditional and contemporary styles and are available in vented and unvented models. They offer realistic flames, good heating capacity, high efficiency and attractive appearance.
Stove sizes vary, with some units being only 17 inches deep. They are available in durable cast iron or steel and come in a range of decorator colors. They use an internal fan to produce convection heat and their metal cabinets and glass windows provide radiant heat. Some units have fans with variable speeds to keep the heat output even.
