Glossary of Terms

A part of pressure regulator that is used to regulate gas pressure. It should only be set with the use of a manometer or pressure guage.

Below is a glossary of definitions for commanly used terms in the hearth industry. Often when shopping for a new stove, insert or fireplace you'll come accross terms & acronyms that you may not have heard before & are specific to hearth products. This tool is designed to help you understand all the ins & outs of your new appliance.

Class of compounds with distinct pungent odor, produced during incomplete combustion of a fuel gas

A measurement for rating furnaces and wall heaters as an official heat source.

The appliance component, usually part of the combination valve which maintains constant gas pressure.

A safety shut off device. Proves the flame and the control center maintains the gas flow.

A measure of heat energy, the amount of heat required to raise the temperature of one pound of water one degree fahrenheit at sea level (comparable to the amount of heat from one kitchen match).

A device for a final conveyance of gas or a mixture of gas and air to the combustion zone. The gas burners in gas burning appliances are made of either aluminized steel, stainless steel or ceramic. They come in many different styles.

A toxic, odorless, colorless cumbistible gas formed from incomplete combustion.

A vertical or nearly vertical passageway to exhaust flue or vent gases to the outside atmosphere.

Gas valve, which combines control functions; usually consists of manual gas valve assembly, pilot safety shutoff system, diaphragm valve, gas pressure regulator, and valve operator.

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 applainces. Such material shall be considered as combustible even though flameproof, fire retardant treated, or plastered.

Rapid Oxidation of fuel gases occompanied by the production of heat, or heat and light. Requires proper amounts of fuel, oxygen, and heat.

Required amount of air that must mix with 1 cubic foot of gas to have complete combustion (NG10-1 and LP24-1).

Bimetallic device designed to react to excessive temperature by causing gas flow to be cut off.

Colorless, odorless, and non-toxic gas separated from wet natural gas, light crude oil and refinery gases.

Instructions and recommendations for proper assembly, adjustments and installation of listed equipment.

A field-constructed chimney of solid masonry units, including brick, stone, listed masonry material, usually lined with fire clay flue liners.

A device consisting of one or more meters used to measure two or more electrical quantities in an electrical circuit, such as voltage, resistance and current.

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

Colorless, odorless, non-toxic, and highly flamable gas. Consists mainly of methane.

Material added to natural gas or LPG in small concentrations to impart a detectable distinct odor. Usually mercaptan.

A device that is part of automatic valve that activates the flow of gas to the main burner. Usually, it is activated electrically.

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

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

A self contained, free-standing fuel gas burning appliance designed for installation only in a vented fireplace and whose primary function lies in the aesthetic efficts of the flame (glas logs).

A vented appliance whose only function lies in the aesthetic effect of the flames.

Part of pressure regulator which responds to changes in gas pressure to maintain constant outgoing pressure.

A part of the pilot burner that directs the flame against a control device and then out across the main burner. AKA: pilot hood.

A type of intermittent ignition system that requires 110 VAC and ignites the gas directly at the main burner by means of a spark.

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.

A device to light the burner or pilot that requires electrical current but not a match.

A listed, manufatured chimney system, usually comprised of combinations of galvanized and stainless steel. May be air-cooled, insulated, or a combination of the two designs.

An elcosure, open in the front, for burning fuel. Solid fuel fireplaces may contain and vent gas log sets or fireplace inserts. Gas fireplaces are metal appliances that can be openable & draw air from within the room or completely sealed drawing air through direct vent technology as seen in higher efficiency fireplaces.

A gas, wood or pellet applaince designed to be inserted within an existing fireplace. Usually gas logs within a metal enclosure that surrounds the logs and covers the space between insert and the fireplace opening in the case of a gas appliance. A wood or pellet insert is much like a wood stove in that it is an enclosed firebox designed for burning fuel.

noncombustible devices that seal opening seperating levels or a building to prevent or retard spread of smoke or fire from one level to another.

Means to ensure gas shut off in the absence of flame in electronic ignition systems. Alternating current applied to an electrode engulfed in the burner flame is rectified, or changed to direct current, to power a control module that maintains gas flow until the flame is extinguished.

Minimum and maximum amounts of fuel (expressed as a percentage) in an air and fuel mixture within which combustion can take place.

A type of main gas burner where the gas and primary air pass through the constricted area of a main gas burner.

Also called valve control, a part of the combination valve that is multi-positioned and tapered valve. When in the "ON" position, it allows for the flow of gas to the burner. In the "OFF" position it shuts off the gas supply to the appliance.

A factory-made, listed venting system designed to remove flue gases to the outside atmosphere.

A means to hold glass panels in place on gas fireplaces, not used on all models hand tighten only.

Amount of heat potential of one cubic foot of gas when burned. (NG 1000 BTU, LP 2500 BTU)

Improper air/fuel mixture or inadequate temperatures resulting in less than complete burning of fuel. May produce aldehydes and/or carbon monoxide, or soot.

A type of double-walled special vent supplied by the manufacturer that normally vents through a side wall in a horizontal position. The inner surface removes the flue gases and the outer container provides for passage of combustion air.

The weight of one substance compared to the weight of another substance, both of equal volume and measured at the same temperature and pressure.

A process that occurrs when flue gases cannot exit the vent system and backs up into the dwelling. THis uslaly creats a dangerous situation as well as incomplete combustion which may result in the production of carbon monoxide.

A means to light the main gas burner through the use of a standing pilot light.

A device consisting of two pieces of dissimilar metals joined together at one end (hot junction). When the hot juction is heated, the thermocouple produces DC (direct current) voltage across

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

A vented appliance whose only function lies in the aesthetic effect of the flames.

A vented, self-contained, free-standing, non-recessed gas burning appliance for firnishing warm air to the space in which installed, directly from the heater without duct connections.

A self contained vented appliance complete with grills or equivalent, designed for permanent attachment to the structure and furnishing heated air by gravity or fan.

A continuous open passageway from the flue collar or draft hood of a gas burning appliance to the outside atmosphere for the purpose of removing flue or vent gas.

Part of pressure regulator, located in the chamber above the diaphragm. An opening which allowd for the free flow of air in and out in the area above the diaphragm. Also provides for the escape of fuel gas in the event of a diaphragm rupture.

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

A part of the pilot assembly that directs the flame against the thermpcouple/thermopile and across the main burner. Many are multi-directional. On gas appliances with a piezo ignitor a spark electrode is located at pilot hood that provides the necessary heat to ignite the pilot gas.

A part of the combination valve which has an adjustment to insure constant and proper volume of gas flow to the pilot burner through the pilot tube.

A method used to check for leaks that is conducted on gas supply line prior to installation of the appliance. The pipe system is plugged on both ends adn pressurized up to about 1/2 PSI.

Gas appliance designed to exhaust all flue gases and combustion by-products back into the dwelling. Not allowed in some code jurisdictions.

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

Gas appliance designed to exhaust all flue gases and combustion by-products back into the dwelling. Not allowed in some code jurisdictions.

A listed, factory-built, double wall metal pipe for venting appliances with draft hoods and other appliances listed for use with Type B gas vent. B-vent appliances draw air from within the room for combustion.

A listed, factory-built, double wall metal pipe for venting appliances with draft hoos and other appliances listed for use with Type B gas vent. B-vent appliances draw air from within the room for combustion.

Gas appliance designed to exhaust all flue gases and combustion by-products back into the dwelling. Not allowed in some code jurisdictions.