a popular accessory to help boost combustion in wood fires, feeding air to the flames as it is forced out of an expandable bladder. Though unnecessary for a gas hearth where the combustion level is easily controlled with the turn of a knob, bellows’ lovely finish in attractive blends of fine woods with vinyl or leather makes them a decorative accessory.


British Thermal Unit, the primary heat measurement unit used by the hearth industry. It is the amount of energy required to raise the temperature of 1lb. of water by 1 degree F.

Catalytic Combustor

a device used on some wood stoves to increase combustion efficiency by lowering flue gas ignition temperatures.


the distance required by manufacturers and building codes between stove, connector pipe or chimney and any combustible materials.


deposits of condensed wood smoke in the chimney and connector pipe resulting from incomplete combustion. It can ignite and cause a chimney fire.

Direct Vent

an appliance with a sealed, specifically designed venting system, that draws combustion air from outdoors and exhausts its combustion products to the outdoors, eliminating the need for a standard chimney system. A glass panel in direct vent units is critical to keeping the combustion system sealed from the home.


unburned gases and particles as a result of incomplete combustion.

EPA Regulations

government regulations of wood-burning appliances mandating that products sold after July 1, 1992, emit no more than 4.1 grams of particulate matter per hour for catalytic-equipped units and no more than 7.5 grams for non-catalytic-equipped units.

Fireplace Inserts

heating units that retrofit into an existing fireplace (masonry or factory-built). They burn wood, gas or wood pellets and offer superior efficiency.


the passageway in a chimney for conveying gases to the outdoors.

Freestanding Stove

a heating appliance normally on legs or a pedestal.

Gas Logs

an open flame appliance with ceramic or ceramic fiber logs placed over a burner to provide dramatic realism of a traditional flame. Manufactured log sets have a burner that uses either natural gas or propane.

Glass Doors

doors attached to a fireplace to close off the opening of the hearth from the home in an attempt to control heat from escaping up the chimney and prevent cold air from entering the home when the fireplace is not being used.


a metal frame used to hold and contain burning fuel in a fireplace.


traditionally refers to the floor of a fireplace on which a blaze is built. Today it is also used to refer to all the devices and equipment used in connection with the fireplace and the stove industry.

Heat Shield

a noncombustible protector used around appliances, smoke pipes or chimneys to protect combustibles from heat sources.


a container attached to an appliance in which fuel, either coal, nuggets or wood pellets, is stored and from which the fuel is fed to the burner.

Island Fireplace

a fireplace that has four sides of glass, for viewing from any angle.


thin, dry wood used to start a fire.

Liquid Propane

Liquefied petroleum gas, available in cylinders, for home use.


an ornamental facing surrounding the fireplace or simply a shelf above a fireplace.

Metal Liner

used primarily with fireplace inserts and placed inside an existing chimney (usually masonry) to reduce the diameter of the flue for more rapid exit of smoke and combustion gases. Also used when an existing chimney is unlimited or deteriorating.

Natural draft (B-vent) Appliances

a gas-burning appliance that takes in combustion air from the home and vents byproducts of combustion outside the home.

Natural Gas

clean-burning fossil fuel transported to homes via an extensive pipeline network.


are made of 100% compressed wood sawdust with no additives. A renewable fuel source made from sawdust or wood chips otherwise destined for landfills.

Peninsula Fireplace

a fireplace that has glass on three sides of glass.


refers to cordwood that has been allowed to dry before burning. Seasoning generally takes a minimum of 12 months. Wood burns much more efficiently when its moisture content has been reduced.

Zero-Clearance Fireplace

a factory-built fireplace that is constructed so that it can be placed, safely, with close clearances to combustible materials.