Definitions of Words Used in Wood Heating

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Add-on (furnace or boiler) means a solid fuel burning appliance designed to share the heat distribution system connected to an oil, gas, or electric appliance; the controls of the add-on are interconnected with the existing appliance.

Air-Circulating Blower consists of the complete blower assembly including the blower wheel (or fan), the blower housing, the motor, and the drive used to circulate air through a forced-air furnace and its duct system.

Air-Fuel Ratio means the weight of air per weight of fuel.

Air Supply (in relation to the installation of an appliance) is the total of combustion air, flue gas dilution air, and ventilation air required for effec­tive operation.

Combustion Air is the air required for satisfactory combustion of fuel, including excess air.

Excess Air is air admitted to the combustion chamber of an appliance that is in excess of that theoretically needed for complete oxidation of the reactive components of the fuel.

Flue Gas Dilution Air is air admitted to an appliance or venting system to stabilize or neutralize the effect of the chimney draft on an appliance.

Primary Air is that portion of the combustion air that is supplied for the initial stages of the combustion process and is supplied upstream from the point of ignition.

Secondary Air is that portion of the com­bustion air that is supplied for the intermedi­ate and final stages of the combustion process and is supplied downstream from the point of ignition.

Ventilation Air is air admitted to a space containing an appliance to replace air ex­hausted through a ventilation opening or by means of ex filtration.

Air Temperature Rise (produced by a forced-air furnace) means the difference in temperature between the average temperature of the air discharged from the hot air supply plenum, and the average temperature of the air entering the cold air return plenum.

Airtight Appliance (See Controlled Combustion)

Appliance means a device to convert the energy in fuel to useful heat, and includes all compo­nents, controls, wiring, and piping required to be part of the device by the applicable standard.

Appliance, Automatically Controlled means an appliance provided with a sensor or sensors that act to control heat output.

Appliance, Central Heating means an appliance designed to supply heat to remote spaces by means of ducts or water pipes.

Appliance, Free Standing means an appli­ance intended for installation in a room in such a manner that it is exposed to the room on all sides, and intended to supply heat without ducts or water pipes.

Appliance, Manually Controlled means an appliance not equipped to automatically regulate the rate of combustion.

Appliance, Space Heating means an appliance designed to supply heat directly to the space in which it is located by means of radiation or convection.

Appliance Label (nameplate) is a sheet of metal, foil, or other material permanently affixed to an appliance that displays the information required for installation and operation, and may bear the mark of the certification (or listing) agency.

Aquastat means a control used in hydronic heating systems for sensing water temperatures, usually including operating and/or safety limit switching functions.

Ash is the noncombustible residue of a coal or wood fire.

Atmospheric Pressure means the weight of a column of air on a unit area at ground level extending from the earth to the upper level of the blanket of air surrounding the earth. This air exerts a pressure of 101.32 kilopascales (14.7 pounds per square inch) at sea level.

Backdrafting means the emission of smoke and/or air through the openings of an appliance when a flow reversal occurs in the chimney, caused by wind conditions or negative pressure within the building.

Back Puffing means the momentary emission of smoke through openings of an appliance when sufficient oxygen is admitted to an oxygen-starved fire to initiate the sudden ignition of combustible gases and a resultant sharp rise in the pressure within the appliance.

Baffle means a stationary device used to divert the flow of fluid (air, water, steam) or flue gases, or to shield parts of an appliance from the ef­fects of flame or heat.

Bank (the fire) means the act of loading and arranging fuel into a wood­ or coal-burning appliance to produce along burn cycle. The term has become somewhat archaic because the technique was mainly used to overcome the lack of burn rate control in leaky cast iron parlour stoves. Modern equipment does not need banking in that sense.

Barrel Stove is a steel drum or barrel converted to a stove by cutting holes and attaching a door, a flue collar and legs. Barrel stoves are rarely used now because they are far to large for modern houses and are too crude to be acceptable to most homeowners.

Biomass is plant matter.

Boiler means an appliance intended to supply hot water or steam for space heating, domestic hot water, processing or power purposes.

Breech means the hole at or near the base of a chimney for receiving flue gases.

BTU (British Thermal Unit) is the quantity of heat required to raise the temperature of one pound of water through one Fahrenheit degree.

BTU/H means one BTU per hour

Burn Cycle is the time interval between the loading of a fuel charge on a bed of coals of a particular weight and the return of the fuel charge and coals to a coal bed of the same weight.

Burn Rate means the weight of a fuel charge divided by the duration of the burn cycle.

Carbon Dioxide is a non-toxic, noncombustible gas formed from the combination of carbon and oxygen during the combustion process.

Carbon Monoxide is a toxic, combustible gas formed during combustion if the reaction is incomplete for any reason such as when insufficient oxy­gen is present for complete combustion.

Catalytic Combustor means a device designed to reduce the ignition temperature of the com­bustible constituents of the flue gas without itself being permanently altered by the combustion process.

Certified (Listed), as applied to appliances, components, and accessories, means investi­gated (tested), and suitably marked with a label by a recognized testing agency as conforming to recognized standards, requirements, or ac­cepted test reports.

Chimney means a primarily vertical shaft enclos­ing at least one flue for conducting flue gases to the outdoors.

Chimney, Concrete or Masonry means a field-constructed chimney of brick, clay, stone, concrete or masonry units.

Chimney, Factory-built means a chimney consisting entirely of factory-made parts, each designed to be assembled with the other without requiring field fabrication.

Chimney Cap, Masonry (Drip Cap, Crown) is a cast-in place or pre-cast concrete unit, or stone unit surrounding the liner at the top of a masonry chimney designed to prevent the entry of rain and snow to the area between the masonry shell and the liner.

Chimney Cap, Factory-built is a stainless steel cover to prevent the entry of rain or snow to the flue of a factory-built chimney. Only a cap specifically listed for use with a particular model of chimney may be used. Such caps may also include features that reduce adverse wind pressures from affecting the upward flow of flue gases and air.

Chimney Capacity means the maximum safe venting capability of a chimney, expressed in terms of the fuel consumption rate of connected appliances (in BTU/h or Kw) but more funda­mentally related to the mass flow (eg. pounds or kilograms per minute) of flue gas which will flow up the chimney under given conditions of tem­perature and atmospheric pressure.

Chimney Connector is the assembly of flue pipes which connects the flue collar of the appli­ance to the chimney flue, thimble or breech. (see flue pipe)

Chimney Effect (see Stack Effect)

Chimney Liner means a heat and corrosion resistant conduit for flue gases inside a chimney.

Clinker is a lump of fused ash resulting from high temperatures combined with other factors.

Coal is a solid fossil fuel composed mainly of carbon.

Anthracite is a high-grade hard coal, high in carbon content and low in volatiles.

Bituminous is a medium-grade soft coal having considerable volatile matter that is given off as a smoky gas when heated.

Lignite is a soft brown to black low-grade coal, frequently woody in appearance and high in moisture content.

Coke is coal that has been heated to drive off volatile matter.

Combustible is a material which is capable of taking fire and burning. Even fire-rated materials such as drywall are considered combustible.     

Combustion means the rapid oxidation of fuel accompanied by the production of heat, or heat and light.

Combustion Chamber means a metal or refrac­tory chamber located within the firebox of an appliance, and used to contain the burning fuel, heat, and/or flame.

Combustion Products means the constituents resulting from the combustion of fuel, including inert materials, but excluding excess air.

Condensate (condensation) is the liquid which separates from gas or from combustion products as the temperature of the mixture falls.

Controlled Combustion refers to appliances having dampers or other controls used to adjust the rate or intensity of combustion and therefore heat output. Wood stoves with this feature were erroneously referred to as airtight in the 1970s and 1980s.

Convection is the transfer of heat by the circula­tion of a fluid (air or water) caused by differences in temperature, and therefore in density.

Cookstove (See Range)

Cord is the common unit of measurement of firewood, equal to the gross volume of a stacked pile of wood measuring 1.2 m high x 1.2 m wide x 2.4 m long (4 feet x 4 feet x 8 feet). The amount of solid wood, excluding bark, in this 3.62 cubic metre (128 cubic-foot) pile is usually between 2.0 and 2.4 cubic metres (71 and 85 cubic feet).

Creosote is the organic components of the flue gas, in solid or liquid form, which condense in the appliance, flue pipe or chimney.

Damper means a movable plate or valve for regulating the flow of air or flue gas.

Check Damper is a device that can be operated manually to reduce excessive draft through a heating appliance by admitting ambient air into the chimney connector downstream of the heating appliance.

Flue Gas Damper (Key Damper) is a damper located in a flue pipe.

Inlet Air Damper is a damper arranged to control the air entering the combustion chamber.

Volume Damper is a damper used to con­trol air flow through a duct.

Draft means the potential for flow of air or com­bustion gases or both, through an appliance and its venting system. Draft is indicated by the difference between the pressure at a specified point in the appliance or venting system and the pressure of the air at the same elevation outside the appli­ance or venting system.

Chimney Draft means the available natural draft measured at or near the base of the chimney.

Forced Draft means a mechanical draft created by a device upstream from the combustion zone of the appliance.

Induced Draft means a mechanical draft created by a device downstream from the combustion zone of the appliance.

Mechanical Draft means a draft created by a mechanical device such as a fan, blower, or aspirator.

Natural Draft means draft other than me­chanical draft.

Draft Control means a control on the upstream or downstream side of the fire used to limit the air available to the fire.

Draft Regulator, Barometric means a draft control device that functions automatically to prevent excessive draft in a fuel-burning appli­ance by admitting air to the venting system.

Efficiency (overall efficiency or appliance effi­ciency) means the percentage of the total en­ergy content of fuel consumed that is delivered to the space to be heated.

Efficiency, Combustion means the per­centage of the total energy content of a fuel consumed that is converted into heat en­ergy.

Efficiency, Thermal or Heat Transfer means the percentage of heat energy that is delivered to the space to be heated.

Emissions, Gaseous means components of the flue gas in gaseous phase.

Emissions, Particulate means components of the flue gas in solid or liquid phase but excluding water, which exit the chimney serving an appliance.

Factory-Built Appliance means an appliance furnished by the manufacturer as a single assembly or as a packaged set of sub-assemblies or parts, and including all the essential components necessary for it to function normally when installed as intended.

Fines are the dust and undersized pieces of pelletized fuel produced during handling.

Firebox means an enclosure in which fuel and gaseous derivatives of fuel are burned.

Firebrick is a refractory brick manufactured from clay that is highly resistant to heat and is used to line combustion chambers.

Fire Chamber is the section of a fireplace in which fuel is burned, including the entire volume bounded by the hearth, chamber walls, and throat.

Fireplace means a fuel-burning device, usually incorporated into the structure of a building, having the major portion of one or more essentially vertical sides open or capable of being opened for refuelling, and intended to permit visual observation of the flames while the fuel is burning.

Fireplace, Circulating means a fireplace with multiple-wall construction which permits room air to circulate between these walls and discharge into the room either directly or via short ducts.

Fireplace, Factory-Built means a circulating fireplace and its chimney, consisting entirely of factory-made parts designed for unit assembly without requiring field construc­tion, commonly referred to as a zero-clear­ance fireplace.

Fireplace Damper (Throat Damper) means a damper used to control the flow of air and flue gases through a fireplace, usually located at the base of the chimney or smoke chamber.

Fireplace Insert means a wood stove adapted by its manufacturer for installation within or partially within the fuel burning space of a masonry fireplace and which substantially closes off the fireplace opening. A few inserts are certified for use in specific models of factory-built fireplaces.

Fireplace Liner (heat form) means a prefabricated steel form, sometimes manufactured in two layers to allow air flow around the fire chamber, used as an alternative to refractory brick for the fire chamber liner in a masonry fireplace.

Floor Pad means a noncombustible surface for ember protection applied to the floor area under­neath and extending in front, to the sides, and to the rear of a wood stove.

Floor Protection means the shielding installed under a heating appliance to prevent overheat­ing of a combustible floor.

Flue means the passage in a chimney for conveying flue gases to the outdoors.

Flue Collar is the portion of a fuel-fired appliance designed for the attachment of the flue pipe.

Flue Gas means combustion products and excess air.

Flue Liner (chimney liner) means a clay, ceramic, or metal conduit in a chimney intended to contain the combustion products and to protect the chimney shell from heat and corrosion.

Flue Pipe means the metal pipe or assembly of pipes extending from the flue collar of an appliance to the chimney and forming the chimney connector.

Furnace means an appliance intended for heating air and having provision for the attachment of ducts for the distribution of this air. (May also refer to the combustion chamber of an industrial boiler)

Gasification means the production of gas from a solid fuel.

Grate is a movable or stationary grid, usually of cast iron or ceramic, on which solid fuel is burned, and which is designed to permit primary combustion air to enter the combustion chamber and/or to allow ashes to fall into an ash pan or pit.        

Grille means a metal grating used to cover ventilation holes in walls or floors.

Hearth is the floor of a combustion chamber more commonly, the floor of a fireplace.

Hearth Extension is a non-combustible surface to protect the floor in front and to the sides of a fireplace hearth.

Hearthmount Stove is a wood stove intended for mounting in the hearth or on the hearth extension of a masonry fireplace and vented through the fireplace chimney.

Heat Exchanger means the enclosure which houses the flue gas passage(s) downstream of a combustion chamber and which is designed for the transfer of heat from the burning fuel to air or water, or it may include all surfaces, including those of the firebox, from which heat is transferred within an appliance casing.

Hydronic Heating System means a fuel-fired or electric heating system using water as the heated medium and piping for the distribution of heat.

Ignition means the establishment of combustion or flame.

Ignition Temperature means the lowest temperature at which combustion is self-sustaining.

Incinerator is a device for the burning of combustible waste materials with little or no use being made of any resultant heat.

Infrared Radiation is that part of the light spectrum that transfers heat energy and is converted into sensible heat when it strikes a solid object.

Lintel, in reference to masonry fireplaces, is the horizontal member, usually masonry or steel, spanning the opening of a masonry fireplace, designed to support the masonry above.

Mantel is a shelf or ornamental ledge above a fireplace opening.

Particulate Fuel means those wood fuels which are intended to be used in particulate or divided form, the size of the individual particles falling within a prescribed range, and which includes woodchips and pellets.

Peat is the fossilized product of partial decay of plants and is a soft organic carboniferous mate­rial not in the coal stage.

Plenum is a sheet metal box mounted on the outlet (supply plenum) or the inlet (return plenum) of a furnace and is intended for the connection of ducts.

Rain Cap is a metal or masonry cap mounted above the top of a chimney flue liner designed to prevent the entry of rain and snow into the flue and, in some cases, to affect draft in the chimney.

Range means an appliance equipped with a cooking surface, an oven and sometimes a tank for heating water.

Refractory means any solid ceramic material suitable for use as a structural and/or protective material for high-temperature and corrosive environments.

Register is a grille with integral dampers placed in walls, floors, and ceilings used to adjust the flow and diffuse air entering a room from a duct.

Return Duct or Pipe means a duct or pipe for conveying air or water from a space being heated, ventilated or air-conditioned back to the heating, ventilating or air-conditioning appliance.

Seasoned Wood is wood that has lost a signifi­cant amount of its original (green) moisture. As-cut moisture content ranges from about 35 to 50 percent by weight, depending on tree species. Seasoned wood is normally considered to be between 15 and 20 percent moisture content.

Smoke Chamber is the chamber in a masonry fireplace immediately above the throat and smoke shelf, and below the chimney flue.

Smoke Pipe (see Flue Pipe)

Soot is a soft, black, powdery deposit of carbon particles in appliances, chimneys or flue pipes.

Space Heater (Room Heater) means an appliance for heating the room or space within which it is located, without the use of ducts.

Spark Arrester means a screen or other device, usually part of a rain cap, to prevent sparks, embers or other burning material from being expelled to the atmosphere.

Stack Effect is the tendency of warm air or gas to rise within a vertical space or conduit because it is lighter than the cooler air outside the space or conduit.

Stove means an appliance intended for space heating, or for space heating and cooking.

Stovepipe (see Flue Pipe)

Supply Duct or Pipe means a duct or pipe for conveying air or water from a heating, ventilating or air-conditioning appliance to a space to be heated, ventilated or air-conditioned.

Sustained Yield means the annual rate at which biomass can be harvested from a geographical area for an infinite period of time.

Thermostat is an automatic control for regulating temperature by controlling a heating or cooling source and/or the distribution of the heated or cooled medium.

Throat is the narrow passage in a fireplace between the firebox and smoke chamber.

Ventilation means the process of supplying outdoor air and/or removing contaminated indoor air by natural or mechanical means to and from any space.

Venting means the removal of flue gases to the outdoors by means of building openings or venting systems.

Vented Appliance means an appliance provided with a flue collar to accommodate a venting system for conveying flue gases to the outdoors.

Volatile Matter means the vapours and tar droplets, mostly hydrocarbons, that are driven off when coal or wood is heated.