Jack Pixley's Chimney Care Dictionary

Accessible (for Inspections) - Capable of being exposed for inspection, maintenance, or repair without damage to the chimney or building structure or finish, but which may require the removal of doors, panel, or coverings using commonly available tools.

AGA - American Gas Association

Air inlet control - wood stove device that helps regulate the amount of combustion air reaching the fire.

Appliance - equipment, usually built in standardized sizes or types, installed or connected as a unit to perform one or more functions.

Approved - acceptable to the authority having jurisdiction. Appliances or installations are not approved unless accepted by the authority having jurisdiction, whether or not they are “tested or listed.”

Aromatic hydrocarbon - a group of hydrocarbon compounds, including benzene and its derivatives, which are among the many compounds found in wood smoke. Consistent exposure to aromatic hydrocarbons has been identified as a cause of cancer.

Ash - The solid residue left when combustible material is thoroughly burned.

Ash door - A door, with a frame, providing access to the ash dump, through which collected ashes can be removed.

Ash dump - an opening, usually with a hinge door and located at the bottom of the fireplace, through which ashes can be dumped. Also the cavity or receptacle below the opening in which ashes collect before removal.

Auger- Rotating screw type device that feeds fuel from a hopper to the combustion chamber - commonly found on pellet stoves.

Authority having jurisdiction - The organization, office or individual responsible for approving equipment, installations or procedures. Includes building or fire inspectors, insurance underwriting departments, or other entities having legal authority to regulate or set standards for acceptability and to enforce them.

BTU - British Thermal Unit - The quantity of heat required to raise the temperature of one pound of water one degree Fahrenheit at or near 39.2º F.

Backpuffing stove - a stove that emits smoke in short, sharp puffs due to a series of small explosions in the stove or venting system.

Baffle - object placed in an appliance to change the direction, extend the path, or slow the flow of air, air-fuel mixtures, or flue gases.

Barometric damper - device which regulates draft and prevents excessive draft in a fuelburning appliance by admitting a controlled amount of air to the venting system under normal burning conditions.

Base assembly - the section of a masonry fireplace that includes the inner hearth, hearth extension, and ash dump.

BOCA - Building Officials and Code Administrators International, an organization that develops model building codes. Boiler - see hot water boiler and low-pressure steam boiler.

Bond - Where referring to bricklaying and masonry chimneys, the connection between brick, stone, or other masonry units formed by lapping them upon one another in carrying up the work, thereby forming an inseparable mass.

Breast - the area located above the damper on the front smoke chamber wall of a masonry fireplace.

Breeching - The conduit conveying flue gas from the appliance to the chimney. (See “Chimney connector” and “Vent connector”.

Carcinogenic - By definition, capable of causing cancer.

Catalytic combustor - a device designed to increase the combustion efficiency of a wood heating system by lowering the ignition temperature of flue gases passing through it. Combustors may be incorporated into the stove design or added to the stove or stovepipe as a retrofit.

Cathedral ceiling - a ceiling, usually sloped, which is formed by the underside of the roof. Central heater - A heat-producing appliance which transfers a heated gas or liquid to areas remote from the appliance location.

CSIA Certified Chimney Sweep® - a person who passes the Chimney Safety Institute of America Certified Chimney Sweep Exam.

CSIA Certified Chimney Sweep® Program - a comprehensive, written, proctored examination developed, administered, and graded by the Chimney Safety Institute of America.

Chase - an enclosure for a chimney that is used to separate the chimney from the living area or to hide an exterior chimney from view.

Chimney - a structure containing one or more passageways, vertical or nearly so, for conveying flue gases from the appliance to the outside atmosphere.

Chimney cap - a protective covering or housing for the top of a chimney intended for preventing the entry of rain, snow, animals, birds, etc., and for preventing downdrafts. Chimney caps are also called rain covers or rain caps.

Chimney connector - The pipe connecting a fuelburning appliance to a chimney. (See “breeching” and “vent connector”).

Chimney crown - mortor or concrete at the top of a chimney that seals off the air space between the outer walls of a masonry chimney and the flue liner and slopes away from the liner to shed water.

Chimney fire - burning of creosote, soot, or other combustible deposits within a chimney or chimney connector.

Chimney Safety Institute of America - a nonprofit, tax-exempt educational foundation dedicated to chimney safety through public education and the development of technical knowledge and educational programs for America’s chimney service professionals.

Circulating stove - a stove which draws in cool air near the stove base, heats the air between the firebox walls and the unit’s outer jacket, and then emits the warmed air to the living space through grating or louvers in the stove covering.

Cleanout opening - an opening or hole in a chimney designed to allow access to the flue or ash dump for purposes of removing ash, creosote, soot and other extraneous matter.

Clearance - distance between a heat producing appliance, chimney, chimney connector, vent, vent connector, or plenum, and other surfaces.

Clinker - hard pieces of fused ash that can form in the firebox of a coal-burning appliance.

Combustible Material - material made of or surfaced with wood, compressed paper, plant fibers, plastics, or other material that can ignite and burn, whether flame-proofed or not, or whether plastered or unplastered.

Combustion - rapid oxidation of fuel accompanied by the production of heat and light.

Combustion Air - The air necessary to provide for the complete combustion of fuel and usually consisting of primary air, secondary air, and excess air.

Combustion chamber - a heavily constructed area designed to withstand direct contact with combustion and to optimize conditions necessary to burn fuel efficiently.

Common Brick - The least expensive red, pink and yellow brick used for construction and lacking attractive texture and water-resistant qualities of face brick.

Connector - the pipe that connects a fuel-burning appliance to a chimney or vent.

Corbel - units of masonry projecting from or stepping upward and outward from the face of a wall or chimney in courses to form a support or ledge for a beam, rafter or other member, or to change the shape or direction of a chimney.

Creosote - chimney and stovepipe deposits originating as condensed wood smoke.

Cricket - a device designed for use with chimneys that penetrate the roof at a location other than the roof peak. Crickets shed water away from the chimney; they are often referred to as saddles.

Damper - a valve, usually a movable or retractable plate, for controlling the flow of air or smoke.

Density - mass per unit volume of material. For wood, density is expressed as pounds per cubic feet.

Dew Point - The temperature at which water vapor in the air begins to condense into droplets.

Dilution Air - The air that enters the relief opening of a draft hood or draft diverter or the air that enters another opening in an appliance flue or venting system.

Direct connect - A connector from an insert or hearth stove to the first flue tile in a fireplace.

Direct Vent Appliance - (Sealed Combustion System Appliance) A system consisting of an appliance, combustion air and flue gas connections between the appliance and the outside atmosphere, and a vent cap supplied by the manufacturer, and constructed so that all air for combustion is obtained from the outside atmosphere and all flue gases are discharged to the outside atmosphere.

Downdraft - draft which forces air to flow down a chimney, rather than up.

Draft - force or pressure difference between the inside and the outside of the venting system which causes gases to flow up and out of the chimney and air to flow into the appliance.

Draft Hood - A nonadjustable device built into an appliance, or made a part of the vent connector from an appliance, that is designed to provide for the ready escape of the flue gases from the appliance in the event of no draft.

Effloresence - A growth of salt crystals on a surface caused by the evaporation of salt-laden water.

Exterior chimney - a chimney whose entire structure is located outside of the exterior wall of a building.

Facebrick - A type of brick made of selected clays and often textured which is highly water-resistant.

Factory-built chimney - chimney composed of listed factory-built components, assembled in accordance with the terms of the listing to form the completed chimney.

Factory-built fireplace - fireplace composed of listed factory-built components, including a chimney, that are assembled in accordance with the terms of the listing to form the completed fireplace.

Fan - A blower of exhauster assembly comprising blades and a housing.

Firebox - chamber of a fireplace or stove where the fire actually burns. See combustion chamber. Firebox assembly - the section of a masonry fireplace that includes the firebrick, lintel, and damper.

Firebrick - brick composed of clay and silica and designed to withstand high temperatures such as those found in a firebox.

Fireclay - clay that withstands high temperatures without deforming or cracking.

Fireplace - hearth, firebox (or similarly prepared place) and a chimney.

Fireplace insert - factory-built, field-installed product consisting of a firebox assembly designed to be installed within or partially within the firebox of a fireplace. Such an assembly often uses the fireplace flue to vent the products of combustion.

Fireplace stove - self-contained, chimney connected, solid fuel burning appliance having its fire chamber open to the room.

Fire pot - area where combustion takes place in stokers and pellet stoves.

Flame Impingement - Ability of the flame to come in contact with another surface.

Flammability - Susceptibility to combustion.

Flashing - sheet metal or other materials used in waterproofing roof valleys, hips, or the angle between a chimney and a roof.

Floating hearth - hearth built over the joists that support the floor.

Flow - amount (volume) of gases that actually pass through the venting system as a result of draft.

Flow capacity - the amount of gases that are able to flow through a venting system in a given time and at a given draft and system resistance.

Flow reversal - a chimney performance problem that occurs because gases are drawn down the flue by low pressure at the bottom of the chimney.

Flue - the passage in a chimney for conveying flue gases to the outside atmosphere.

Flue collar - portion of an appliance that is designed for attachment of a chimney or vent connector or a draft hood.

Flue gases - combustion products from fuelburning appliances plus excess air.

Flue Gas Damper - A damper located on downstream side of combustion chamber of a fuel - burning appliance, usually in a flue passage of the appliance or in the connector pipe leading to the chimney.

Flue gas temperature - temperature of gases in the flue.

Flue liner - special liner required by codes and standards to cover the inner surface of the flue. The liner serves as a buffer between flue gases and chimney walls and is designed to contain the products of combustion.

Fly ash - very lightweight ash, easily picked up by air currents.

Freestanding fireplace - A fireplace that is exposed on all sides and is typically connected to a chimney. These units are often found in the middle of the room.

Freestanding solid fuel heater - a chimneyconnected, solid fuel burning, room heater which is designed to be operated with the fire chamber closed (also known as “freestanding stove”). Furnace - appliance designed to heat air and supply it to areas remote from the appliance location.

Gasketing - special rope or tape-like, noncombustible and compressible material used to make airtight seals around stove doors.

Grate - raised grid-like structure where fuel is placed.

Hardwood - Lumber from trees that shed their broad leaves in the fall. The term hardwood or softwood is not an accurate index of relative hardness. Some softwoods such as southern yellow pine or Douglas fir are much harder than the hardwoods, poplar or basswood.

Header - where referring to chimneys, a beam set at right angles to floor or roof joists to provide support and framing around the opening.

Hearth - floor area within the firebox of a fireplace or a fireplace stove.

Hearth extension - noncombustible surfacing applied to the floor area extending in front of and at the sides of the hearth opening of a fireplace or a fireplace stove; also as applied to the floor area beneath a fireplace stove or beneath an elevated overhanging fireplace hearth.

Hearth stove - stoves which are either specifically designed or adapted for connection to a fireplace.

Heat exchanger - chamber in a heating appliance where heat resulting from combustion of fuel is transferred through the walls of the chamber to air or water passing through the exchanger.

Heat reclaimer - stovepipe accessory designed to extract heat from flue gases.

Heat transfer efficiency - the percentage of useful heat released in the fire which becomes useful heat in the home.

Heatform type fireplaces - see steel fireplace liner.

Heatilator-type fireplace - Brand name describing either a factory built fireplace or steel fireplace liner.

Heating system - heat - producing appliance with a combustion chamber and a heat exchanger.

Histoplasmisosis - a fungal infection of the lungs caused by breathing in dust from soil enriched by bird dung, i.e., soil from chicken coops or fireplace smoke shelves.

Hot water boiler - a closed vessel for heating a liquid or water or for generating vapor or steam by direct application of heat.

IBC - International Building Code

ICBO - International Conference of Building Officials, an organization which develops model building codes.

Ignition Temperature - Lowest temperature of a fuel at which combustion becomes self-sustaining.

IMC - International Mechanical Code

Inadequate flow - chimney performance problem occurring when the flow of gases through a venting system is insufficient to handle the amount of flue gas produced by the fire.

Incinerator - an appliance or combustion chamber which burns garbage, rubbish and other wastes.

Infrared radiation - a form of light, beyond the visible part of the spectrum, which is given off by warm or hot objects and is converted to sensible heat when absorbed by another object.

Inner hearth - floor area within the firebox or fire chamber where the fire is built.

Interior chimney - a chimney that has any part of its structure inside the exterior wall of a building.

INWC - Inches of Water Column. Measure of pressure.

IRC - International Residential Code

Labeled - materials or equipment to which has been attached a label, symbol or other identifying mark of an organization acceptable to the “authority having jurisdiction” and concerned with product evaluation, that maintains periodic inspection of production of labeled equipment or materials and by whose labeling the manufacturer indicates compliance with appropriate standards or performance in a specified manner.

Latent heat - energy used to change a liquid (such as water) to a gas (such as steam) that is released as sensible heat when the gas condenses to its liquid state.

Lintel - when referring to masonry fireplaces, the horizontal noncombustible member, usually of masonry or steel, spanning the opening of a masonry fireplace to support the load above.

Listed - materials or equipment included in a list published by an organization acceptable to the “authority having jurisdiction” and concerned with product evaluation, that maintains periodic inspection of production of listed equipment or materials and whose listing states either that the equipment or material meets appropriate standards or has been tested and found suitable for use in a specified manner.

Low pressure steam boiler - boiler which heats water under pressure to above boiling point and circulates the water to radiators where it is allowed to turn to steam and condense, releasing latent heat.

Manometer - An instrument for measuring the pressures of gases and vapors.

Mantle - a shelf or facing ornament above a fireplace opening.

Masonry chimney - a field-constructed chimney of solid masonry units, bricks, stones, listed masonry chimney units, or reinforced Portland cement concrete, lined with suitable chimney flue liners built in accordance with applicable building code requirements.

Masonry fireplace - a hearth and firebox of solid masonry units such as bricks, stones, listed masonry units, or reinforced concrete, provided with a suitable chimney.

Modular/masonry chimney - a factory-built, listed chimney system composed of engineered, pre-cast masonry units, assembled in the field to form a completed chimney.

Modular/masonry fireplace - fireplace or fireplace liner constructed of engineered pre-cast masonry units.

Mortar - A mixture of cement, sand and water used to bond bricks and stone.

Multi-flue chimney - a single chimney containing more than one flue.

NCSG - National Chimney Sweep Guild, a nonprofit trade association of chimney service companies dedicated to the education of consumers in chimney and venting safety and to professionalism in the chimney service trade.

NFGC - National Fuel Gas Code, also known as NFPA 54

NFPA - National Fire Protection Association, a non-profit, technical, and educational organization to promote the science and improve the methods of fire protection and prevention, to obtain and circulate information on these subjects, and to secure the cooperation of its members and the public in establishing proper safety against loss of life and property by fire.

NFPA 31 - Standard for the Installation of Oil - Burning Equipment

NFPA 211 - National Fire Protection Association standard for chimneys, fireplaces, vents, and solid fuel burning appliances.

NFPA 97M - Glossary of Terms Related to Chimneys, Vents, and Heat Producing Appliances, a standard published by the National Fire Protection Association.

Non-Accessible, Concealed - Not capable of being exposed for inspection, maintenance, or repair without damage to the chimney or building structure or finish, or without the use of special tools.

Noncombustible material - material that, in the form in which it is used and under the conditions anticipated, will not ignite, burn, support combustion, or release flammable vapors when subjected to fire or heat.

ODS Monitor - Oxygen Depletion Sensor.

Offset flue - a flue that is not completely vertical. Outside air combustion kits - a duct with a valve for directing outside air to the firebox for use during combustion.

Parging - a thin coat of mortar applied to the inside of a masonry chimney or to the walls of a smoke chamber.

Particulate - tiny pieces of solid or liquid matter which form the visible components of smoke. Pascal - a metric measure of pressure. 25 Pa=.1 INWC

Pellets - compressed biomass (wood fibers, sawdust or other organic material) used as fuel in pellet stoves.

Pellet Hoppers - fuel storage unit from which fuel is conveyed to a fire pot in pellet stoves.

Pellet Stoves - solid fuel appliance fueled with pellets.

Plenum - an esclosure that serves as a gathering point for the distribution of air in the ducting system.

Positive connect or positive connection - A liner from a hearth stove or insert to the top of the chimney.

Pyrolysis - chemical alteration of wood, coal, or other combustible materials as a result of the application of heat.

Radiant heat - see infrared radiation.

Radiant stove - stove that has its outer firebox walls exposed to the area to be heated; radiant stoves transfer most of their heat in the form of infrared radiation.

Rain cap - cap placed above the flue to prevent rain from entering the flue. See chimney cap.

Residence time - the length of time smoke remains in the venting system.

Residential type chimney - a chimney that vents residential-type gas, liquid, and solid fuel burning appliances. This class of service is based on a maximum continuous appliance outlet flue gas temperature of not greater than 1000 degrees Fahrenheit.

Residential type heating appliance - a heating appliance that vents into a residential type chimney.

Room heater - self-contained appliance designed to heat the area in which it is located.

RValue - A grading standard for insulating materials. It stands for "resistance to heat flow" and is stamped on most insulation material. The higher RValue the better.

SBCCI - Southern Building Codes Congress International, an organization that develops model building codes.

Saddle - see cricket.

Screening - wire mesh installed at the top of the chimney to prevent animals and birds from entering the flue.

Secondary air inlet - a second air inlet in a solid fuel burning stove designed to supply sufficient additional oxygen to combustible volatiles so that they will burn.

Sensible heat - heat which can be sensed, as by the skin; heat which causes a sensible terperature rise in a material.

Shingles - Small rectangular or square pieces of building material laid in overlapping rows on the roof or walls of a house.

Smoke - solid, liquid and gaseous products of combustion that leave the combustion zone unburned and are carried through the venting system by draft. Often the term is used to refer only to the visible portion of the appliance exhaust. See particulate and smoke density. Smoke chamber - chamber in a fireplace directly above the smoke shelf and extending to the base of the flue.

Smoke chamber assembly - the section of a masonry fireplace containing the smoke chamber walls and the smoke shelf, located above the throat and below the flue.

Smoke density - the amount of unburned hydrocarbons in the flue gas.

Smoke shelf - The area at the bottom of the smoke chamber created as the back wall of the firebox arches forward. The shelf is located at the intersection of the smoke chamber and the firebox. A damper is normally located on the forward side of the smoke shelf.

Smoke test - a procedure for ascertaining the tightness of a chimney and for detecting any cracks in a masonry chimney flue or deterioration or breaks in the integrity of a factory-built or metal chimney flue. The procedure involves igniting a smoke bomb or building a smoky fire in a fireplace or a solid-fuel burning appliance, covering the chimney termination, and checking for smoke escaping through the chimney walls.

Softwood - Cone-bearing, evergreen trees which do not shed their needle-like leaves.

Solid fuel - coal, wood, and other similar organic materials and any combination of them.

Soot - soft, black or brown, velvety carbon particle deposits inside appliances, chimneys or connectors, originating in oxygen-poor flames.

Space heater - see room heater

Spall - to chip or flake, usually associated with masonry construction.

Spark arrestor - screening material or screening device attached to a chimney termination to prevent the passage of sparks to the outside atmosphere.

Stack effect - the tendency for warmer air to rise within a structure, creating lower pressure in the lower areas of the building. Stack effect often works against chimney draft, causing poor performance or smoking in appliances situated in the lower levels of the building.

Standard ceiling - a ceiling where the ceiling and the roof line are two separate units, usually separated by an attic.

Steel fireplace unit - a unit consisting of a steel firebox, and an air chamber adjacent to the sides and rear of the firebox, used to construct a masonry fireplace. The unit usually has ducts to circulate air to and heated air from the air chamber to the living space.

Stovepipe - single wall metal pipe used as a general purpose chimney connector.

Thermosyphon - referring to factory-built chimneys, a type of design that uses naturally moving air to cool the inner liner of the flue.

Thimble - fixed or removable ring, tube, or lining usually located in the hole where the chimney connector or vent connector passes through a wall and enters a chimney or vent.

Throat - opening above a fireplace firebox through which flue gases pass from the firebox to the flue. The fireplace damper frame assembly is usually located at the throat of a fireplace. Turbulence - areas of erratic pressure or flow

UL - Underwriters Laboratory, an independent, nonprofit, product safety certification organization. Manufacturers voluntarily submit products, devices, materials, and systems for evaluation of electrical, fire, burn, and casualty hazards. Products that meet UL’s safety requirements are eligible to bear the UL Mark and are subsequently covered by UL’s Follow-up Services program, which continuously monitors all UL Labeled products.

Updraft - normal direction of chimney draft caused by buoyant gases rising within a chimney.

Vent - a vertical or nearly vertical passageway composed of listed vent parts for conveying flue gases of certain gas or oil burning appliances to the outside atmosphere.

Vent Cap - A protective covering or housing attached to the vent termination, intended for preventing down drafts and the entry or rain, snow, birds, and animals.

Vent connector - The pipe that connects a fuelburning appliance to a gas vent or a Type L vent. (See also “Breeching” and “Chimney Connector.”)

Venting system - a system that exhausts products of combustion to the atmosphere.

Video scanner - system, incorporating a closedcircuit video camera and television or monitor, for inspecting the interior of flues and other inaccessible areas.

Wash - A slight slope or beveled edge on the top surface of a chimney designed to shed water away from the flue liner; also called a splay.

Wind-induced downdrafts - downdrafts related to wind which force smoke down the chimney because of unusually high pressure at the top of the flue.

Wythe - a solid masonry partition used to separate individual flues located in a single chimney.