APPLIANCE -- A solid or fossil fuel burning stove, fireplace, furnace, boiler, water heater, heater or cookstove.

B VENT GAS -- Listed, factory-built, double wall metal pipe for venting apliances with draft hoods and other apliances listed for use with Type B Gas Vent.

BTU OR BRITISH THERMAL UNIT -- A unit for measuring energy, equal to the amount of energy needed to increase the temperature of 1 pound of water by 1 degree Fahrenheit.

CAST IRON STOVE -- Cast iron is a material used in many stoves. Iron is heated to a liquid form and poured into molds, usually having decorative features.

CHASE -- A structure built around, and enclosing, portions of chimney exterior to the house.

CHIMNEY -- A portion of the venting system, through which flue gases are vented to the outdoors, and by which penetrated combustible surfaces are protected; a primarily vertical shaft enclosing at least one flue, the design of which results in a natural draft.

CIRCULATING FIREPLACE -- A fireplace with multiple-wall construction around the fire chamber which permits air to circulate between the walls, become heated, and enter the house directly or via short ducts.

CIRCULATING STOVE -- Also see circulating fireplace. A stove with an outer jacket (usually sheet metal) beyond the main structure, with openings at or near the bottom and top so that air can circulate between the stove body and its jacket. For purposes of determining safe clearances, a circulating stove must be fully jacketed on all four sides, including at the access doors and on the top.

CLEARANCES -- Minimum distance, composed only of an air space, which must be maintained between a heat source such as an appliance or vent and combustible surfaces.

CLEARANCES -- Distance required by building and fire codes between stove, smokepipe, or chimney and combustible materials such as wood furniture or carpets. Clearances must be obeyed even if the combustible materials are wood furniture or carpets. Clearances must be obeyed even if the combustible material is covered by noncombustible plaster or other masonry materials.

COMBUSTIBLE MATERIAL -- Material made of, or surfaced with, wood, compressed paper, plant fibers, or other material that will ignite and burn, as applied to materials adjacent to or in contact with heat-producing appliances, chimney connectors, steam and hot water pipes and warm air ducts. Such material shall be considered as combustible even though flameproofed, fire retardant treated, or plastered.

COMBUSTIBLES -- (as applied to walls, floors and ceilings in the context of wood heater clearances for safety). Constructed of, or surfaced with, wood, paper, natural- or synthetic fiber cloth, plastic or other material which will ignite and burn, whether flame-proofed or not and whether plastered or unplastered. Combustibility is a relative concept. This definition is adapted from the definition found in the NFPA booklet glossary of terms relating to heat-producing appliances.

COMBUSTION -- The process of burning, or oxidation accompanied by heat. When sufficiently rapid, also accompanied by light.

DAMPER -- A valve, usually a moveable or rotatable plate, for controlling the flow of air or smoke and draft.

DECORATIVE GAS APPLIANCE IN A VENTED FIREPLACE -- A self-contained, freestanding fuel/gas-burning appliance designed for installation only in a vented fireplace and whose primary function lies in the aesthetic effects of the flame. Gas hearth appliances which are listed to ANSI Standard Z21.60 include gas log sets.

DIRECT VENT APPLIANCES -- Direct vent hearth appliances draw combustion air from outdoors and exhaust 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, maintaining high efficiency and indoor air quality.

DIRECT VENT -- a.Method of venting appliance whereby all air for combustion is derived directly from the outside atmosphere and all flue gases are discharged directly to the outside atmosphere.

DIRECT VENT -- b.Exhaust system for gas fireplaces that can be power or gravity induced. No chimney is required.

EFFICIENCY -- The percentage of heat that goes into the room instead of up the chimney. 70-80% efficiency is optimal.

ENAMEL -- A permanent baked on heat-resistant, glossy, colored finish used on the outside of a cast iron stove.

ENERGY EFFICIENCY -- The percentage of the total energy content of the fuel consumed that becomes useful heat in the house.

EPA PHASE I AND II -- Environmental Protection Agency particulate emissions standards for solid-fuel stoves, designed to reduce pollution. Implemented in 1988 (phase I) and 1990 (Phase II).

EPA REGULATIONS -- Government regulation of woodburning 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.

A-E | F-J | K-O | P-T | U-Z

FACTORY BUILT FIREPLACE -- Prefabricated metal fire chamber and its chimney, commonly called zero clearance. Consists of listed manufactured components that are assembled in accordance with the terms of the listing to form the completed fireplace.

FACTORY-BUILT CHIMNEY -- A chimney composed entirely of listed manufactured components, designed to be assembled as an entire system in accordance with the terms of the listing.

FIREBOX --

FIRE CHAMBER -- See Firebox

FIRE RESISTANCE RATING -- The time a material will withstand, without igniting, flame and heat as specified by code and specific test conditions.

FIREPLACE -- An enclosure, open in the front, used to burn fuel. Solid fuel fireplaces may contain, and vent, gas log sets or fireplace inserts. Gas fireplaces are metal appliances open in the front and containing artificial log sets.

FIREPLACE INSERT -- a.A heating unit that retrofits into an existing fireplace (masonry or factory-built). It burns wood, gas or wood pellets and offers superior efficiency.

FIREPLACE INSERT -- b.Solid fuel appliance designed to be installed partially or fully in the firebox of a masonry fireplace, and which vents into the fireplace chimney by means of full relining or appliance to flue methods.

FIREPLACE STOVE -- A free-standing solid fuel burning room heating appliance operated either with its fire chamber open or closed to the room. NFPA and most codes use the term room heater-fireplace stove combination for a fireplace stove, and use the term fireplace stove to designate a unit without doors, that has its firechamber always open to the room.

FIREPLACE, ZERO CLEARANCE -- A factory-built metal fireplace with multi-layer construction providing enough insulation and/or air cooling so that the base, back, and in some cases sides, can safely be placed in direct contact (zero clearance) with combustible floors and walls.

FLUE -- The passageway in a chimney for conveying flue gases to the outside atmosphere.

FLUE GASES -- The gases in an operating venting system, consisting of combustion products plus whatever air is mixed with them. Essentially synonymous with smoke and stack gases.

FREESTANDING GAS APPLIANCE -- An appliance with gas burning log set that has the appearance of a solid fuel appliance that is placed away from walls in a dwelling.

FREESTANDING STOVE -- Heating appliance normally on legs or a pedestal that occupies an area roughly equal to that of an easy chair.

FURNACE -- A central heating appliance that supplies hot air, through ducts, to the house.

GAS COCK ASSEMBLY -- Part of the combination valve that is a multi-positioned and tapered valve designed to allow or shut off gas supply to the appliance. Also known as valve control.

GAS FIREPLACE INSERT -- A gas appliance designed to be installed within an existing fireplace. Usually gas logs within a metal enclosure that surrounds the logs and covers the space between itself and the fireplace opening.

GAS LOGS -- a.An open flame type appliance consisting of a burner and metal pan or base supporting simulated logs. May include various ember media.

GAS LOGS -- b.Provide dramatic realism from the life-like ceramic fiber, concrete or refractory logs down to the glowing embers. Manufactured log sets have a burner that uses either natural gas or propane.

GAS VENT -- A factory made, listed venting system designed to remove flue gases to the outside atmosphere. Please also see Direct Vent and Type B vent.

GLASS DOORS -- a.Used with an open fireplace to reduce draft when fireplace is not in use.

GLASS DOORS -- b.Used with an open fireplace to reduce air flow.

GRATE -- A metal plate with engineered holes or a framework of metal bars used to hold fuel in the burnpot and to allow ashes to drop through to the ash drawer.

GRAVITY VENT -- Type of venting that uses the natural draft of a column of warm gases rising due to the pressure of surrounding cooler air.

HEARTH -- a.Traditionally refers to the floor of a fireplace on which a blaze is built. Now also used to refer to all the devices and equipment used in connection with the fireplace and stove industry.

HEARTH -- b.The floor of the firebox, most commonly used in reference to fireplaces. More generally, the foundation upon which fires for aesthetic and heating purposes are built. Differs from floor protection.

HEARTH -- c.The fire resistant surface under your stove, often made of brick, or tile.

HEARTH EXTENSION -- Noncombustible floor protection extension beyond the opening of a fireplace or stove. The term is also sometimes used to denote the floor protector under or around any residential solid fuel burning appliance.

HEAT LOSS CALCULATION -- Calculation to determine house BTU loss; factors include conduction through construction materials, air infiltration losses and the difference between actual or projected outside temperatures and desired temperatures inside the house. Used for determining necessary heat output from the heating appliance.

HEAT OUTPUT -- The amount of usuable heat produced by a heating appliance; expressed in BTU (for solid fuel and most conventional fuel appliances) or watts per hour.

HEAT SHIELD -- Refers to a non-combustible protector used around appliances, or smokepipe.

HEAT TRANSFER EFFICIENCY -- The percentage of heat, which is released in the fire, that gets through the appliance and chimney walls to become useful heat in the house.

INFRARED RADIATION -- The invisible and harmless radiation emitted by a hot object. This radiation is converted into heat when it is absorbed.

ISLAND FIREPLACE -- Fireplace that has four sides of glass, for viewing from any angle.

A-E | F-J | K-O | P-T | U-Z

K VALUE -- Indicates the amount of BTUs of heat that will flow in one hour through one square foot of a uniform material one inch thick for each degree Fahrenheit of temperature rise. Used in calculating floor protection materials and tichkness when one noncombustible material is used.

LABELED -- Equipment or material identified as having undergone approved inspection and compliance manufacturing and performance procedures.

LIQUIFIED PETROLEUM GAS (LPG) -- Colorless, odorless, and non-toxic gas separated from wet natural gas, light crude oil, and oil refinery gases. Composed predominantly of following hydrocarbons or mixtures thereof: propane, propylene, normal butane or isobutane and butylenes. Please also see Liquid Propane.

LIQUID PROPANE -- Liquified Petroleum Gas, available in cylinders, for home use. Please also see Liquified Petroleum Gas.

LISTED -- Included in a list published by a recognized testing laboratory or inspection agency, indicating that the equipment meets nationally recognized safety standards.

MAIN GAS BURNER -- Device for the final conveyance of gas or a mixture of gas and air to the combustion zone. Consists of burner orifice, air shutter, mixer, and burner head.

MANIFOLD -- The conduit of an appliance which supplies gas to the individual burners.

MANIFOLD PRESSURE -- Gas pressure between the combination valve and the burner orifice.

MANOMETER -- Instrument used for measuring the pressure of gases.

MANTEL -- Shelf over and above the fireplace opening. Stone, brick or wood may be used.

MANUFACTURERS INSTALLATION INSTRUCTIONS -- Instructions and recommendations for proper assembly, adjustment, and installation of listed equipment.

MASONRY CHIMNEY -- Chimney constructed on site of masonry and fire clay materials; construction requirements specified by code. Also refers to existing masonry chimneys of various constructions.

MECHANICAL SIDEWALL VENTING -- Totally horizontal through the wall venting of combustion by products under positive pressure by means of an electric fan. Commonly referred to as Direct Vent, but termination conditions differ. See Direct Vent.

METHANE -- Main constituent of natural gas. Chemical formula CH4.

MILLIVOLT (MV) -- Unit of electromotive force equal to one one-thousandth of a volt.

MIXER -- Component of a main burner where gas mixes with air. Consists of mixer face, mixer head, and mixing tube (venturi).

MOBILE HOME APPLIANCE -- Solid fuel appliance specifically designed to meet HUD standards for installation into mobile homes. Includes outside combustion air, floor mountings, substantially reduced clearances, and designated venting systems.

NATIONAL FUEL GAS CODE (ANSI Z23.1, NFPA 54) -- A standard for the installation of gas appliances, piping and venting.

NATURAL DRAFT -- (B-vent) Appliances-Natural draft hearth appliances take in combustion air from the home and vent products of combustion outside the home.

NATURAL GAS -- a.Clean-burning fossil fuel available in vast quantities throughout North America and delivered to homes via an extensive pipeline network. NATURAL GAS -- b.Colorless, highly flammable gas found in porous geologic formations beneath the earths surface. Consists mainly of methane.

NFPA -- The National Fire Protection Association, 470 Atlantic Avenue, Boston, MA 02210. An independent not-for-profit organization for fire safety.

ORIFICE -- The opening in a cap, spud, or other device whereby the flow of gas is limited and or controlled and through which the gas is discharged to either a pilot burner or main burner.

A-E | F-J | K-O | P-T | U-Z

PENINSULA FIREPLACE -- A fireplace that has three sides of glass.

PIEZO IGNITOR -- A device which delivers an igniting spark by means of pressure on a crystal.

PILOT -- A small flame used to ignite the gas at the main burner. May be standing (constantly burning) or intermittent (on demand for heat).

PRESSURE REGULATOR -- A device for controlling and maintaining a uniform outlet gas pressure. Service regulators reduce high street pressure of natural gas or reduce LPG storage tank pressure. Appliance regulators, usually part of the combination valve, reduce, adjust and maintain constant pressure to be used in an appliance.

PRESSURE TEST -- Method of checking for leaks in the gas supply line prior to installation of applianes.

PRIMARY AIR -- Combustion air directed to the firebox where the fuel is located; supports all stages of combustion

PRIMARY COMBUSTION -- The burning of solid wood and some of the combustible gases, which takes place in that portion of the appliance that holds the wood. The distinction between primary and secondary combustion is somewhat artificial.

PROPANE -- A colorless, odorless, nontoxic LPG containing more heat value than natural gas.

PSI -- Pounds of pressure per square inch.

R-VALUE (RESISTANCE VALUE) -- A measure of how resistant a substance is to transferring heat.

RADIANT STOVE -- A stove whose heat output is mostly in the form of radiant energy. The exterior of the stove is tremendously hot and room air circulates around the body of the stove giving off heat.

RADIATION -- Heat that moves out in waves from a central point and heats objects in its path. The closer you get to a source of radiant heat the more heat you will feel.

REFRACTORY -- Any solid ceramic material suitable as a structural or protective material at high temperatures iin a corrosive environment.

REFRACTORY MORTAR -- High temperature masonry mortar used primarily to join flue liners. Required by NFPA as medium duty, non water-soluable calcium aluminate refractory cement mixture, or its equivalent.

SAFETY PILOT SHUTOFF VALVE -- A component of the pilot or the combination gas valve that allows or shuts off gas flow on the basis of the presence or absence of flame. Consists of a u-shaped electromagnet (see solenoid), gas shutoff disc, tension spring, keeper plate, thermocouple/thermopile connection, and a reset button. Also known as millivolt system and electromagnetic power unit (EPU).

SAFETY SHUTOFF -- A device, usually powered by a thermocouple/thermopile, designed to shut off the gas supply to the pilot and or main burner if the source of ignition fails.

SECONDARY AIR -- Combustion air directed downstream of the primary combustion zone (but still in the appliance) to support the combustion of remaining combustible gases; does not directly influence the rate of primary combustion.

SEDIMENT TRAP -- In gas piping, a tee device to intercept or hold solid foreign particles to prevent them from blocking valves or ofifices. If not part of an appliance, must be installed as close to appliance inlet as possible.

SILICONE SEALANT -- Process of sealing cracks with a high temperature silicone sealant.

SMOKE -- The visible portion of flue gases composed of solid, liquid and gaseous products of combustion. Commonly used to refer to all exhaust from solid fuel burning.

SOLID FUEL -- Wood, coal, and other similar organic materials in various forms (e.g. chunk wood, pressed logs, wood pellets, wood chips, paper, processed coal, coke, peat, charcoal)

STEEL LINED FIREPLACE -- Masonry fireplace with prefabricated metal firebox which has all the components of traditional fireplaces; may have double walls to provide circulating air passage behind the fire chamber.

STOVE -- Wood or coal stove. A freestanding solid fuel burning, room heating appliance intended to be operated with its door(s) closed, i.e. with a closed fire chamber. NFPA and most codes use the term solid fuel room heater for stoves.

TEMPERATURE DIFFERENTIAL -- The difference in temperature between two areas, such as inside and outside the chimney or house. (Example, if it is 90 degrees F. outside the house and 70 degrees F. inside the house the temperature differential is 20 degrees F.)

THERM -- 100,000 British Thermal Units (BTUs)

THERMOCOUPLE -- A device consisting of two pieces of dissimilar metals joined together at one end (hot junction). When the hot junction is heated, the thermocouple produces DC voltage across the other end. Used to power thermoelectric gas valves.

THERMOPILE -- A number of thermocouples connected in series to produce a higher voltage than a single thermocouple.

THERMOSTAT -- An automatic device for regulating the temperature in a building by controlling the heating or cooling source or its distribution.

A-E | F-J | K-O | P-T | U- Z

U.L. LISTED -- Underwriters Laboratories, Inc. 333 Pfingsten Road, Northbrook IL, 60062. An independent not-for-profit organization testing for public safety.

UNVENTED ROOM HEATER -- category of unvented, self-contained, free standing, non recessed (except as noted) fuel gas burning appliance for furnishing warm air by gravity or fan without duct connection. Gas hearth appliances listed to ANSI Standard Z21.11.2 include Gas Fireplaces and Fireplace Inserts.

UNVENTED OR VENT-FREE APPLIANCES -- Unvented or vent-free refers to the kind of hearth appliances that draws its combustion air from inside the home and is designed to burn so efficiently that it eliminates the need for venting.

VENTED DECORATIVE APPLIANCES -- A vented appliance whose only function lies in the aesthetic effect of the flames. Gas hearth appliances tested to ANSI Standard Z.21.50 include gas fireplaces, fireplace inserts, and freestanding appliances.

VENT FREE -- Gas appliances that have no need of a flue.

VENT-FREE APPLIANCES OR UNVENTED -- Vent-free or unvented refers to the kind of hearth appliances that draw its combustion air from inside the home and are designed to burn so efficiently as to eliminate the need for venting.

VENTING SYSTEM -- A continuous open passageway from the flue collar or draft hood of the appliance to the outside atmosphere for the purpose of removing flue gases.

WATER COLUMN (WC) -- Measurement in inches of pressure of gas. 28 inches wc equals one psi.

ZERO CLEARANCE FIREPLACE -- A factory built fireplace that is constructed so that it can be placed safely close to combustible materials.