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The world of chimney sweeps can involve technical terms and jargon. Here is a simple A to Z glossary to help explain the meanings behind the words. This guide will give you a clearer understanding of the processes, products and equipment involved in sweeping. 

Air Inlet Control

This device manipulates air quantity for combustion, either manually or automatically.

Air Wash

This is the process of a secondary air flow to prevent staining, which enters an indoor fire set-up with a glass front, by being sucked down the inward surface of the window.

A term used as a measurement for light reflection on a surface. Darker colours tend to blend in whilst lighter tones, even heat-associated infra-red light, reflect light.

This is a mineral coal which is considered to be the purest with a higher carbon count than other coals. It is created deep below ground and is 300 million years old.

Burnt fuel leaves an incombustible and dusty residue. This is ash, a compound essence, which is neither organic or water-based.


This device is designed to catch residue in a firebed and can be removed


The chamber basin for cradling the ashpan, which is usually designed to catch residue as well, from the firebed.

Baffle Plate or Throat Plate
The plate slows down fire gas flow, located above a firebed in an appliance, to speed efficiency. It is either metal or ceramic in construction.

Basic Firebed
This is the quantity of glowing embers, which lifts ignition for a test fuel and allows it to charge.

Boiler Vessel
Part of the solid fuel allowance, which heats water even when the appliance is not boiling at 100°C.

Boiler Waterways
Compartments within a boiler for hosting water.

Bottomgrate or Grate
A layer within an appliance for hosting the firebed, which lets residue drop into an ashpan or ashpit and gives a route for drawing combustion air or gas.

Coke waste, usually in a form of powder.

Burning Rate
A measurement of fuel mass reduction, per time unit. It is typically displayed as kilogrammes per hour.

Carbon Monoxide (CO)
This is a deadly, poisonous gas, which has no colour or smell. It is created by the combustion of carbon (or similar material) from nearly all solid fuels.

Catalytic Converter
This is a set-up of substances, intended to slow down chemical reactions, which form energy. An example would be ceramic meshes saturated with heavy metals, such as osmium, that allow the passage of fire gases. The catalyst, without being changed itself, stops the temperature of carbon-to-carbon monoxide conversion and carbon monoxide.

Charging Door
Hatch cover for the refuel opening.

The complete flue structure.

Chimney Stack
Part of the chimney visible on a building’s roof.

A carbon-packed mineral, which is formed by pressure over a period of up to 400 million years on broken wooden material. The phrase ‘coal’ or ‘charcoal’ commonly refers to any mineral or wooden lumps of fuel.

Solid residue, used as a fuel, formed from impure carbon after a destructive distillation process. The residue is taken from carbonaceous material such as bituminous coal, after detaching volatile substances.

Combustion Air
Air for burning fuel, completely or partially, when routed to a firebox.

Combustion Air Selector
The device for altering air flow, whether primary or secondary, according to the fuel being burnt.

Combustion Control Device
An apparatus for changing primary or secondary air, according to the burning rate.

Combustion Gases
Compounds formed from gas because of fuel burning inside an appliance.

The displacement of heat or electricity via a material.


Heat flow via a gas or a liquid. It circulates by rising, cooling and sinking, as found in contained heating appliances.

Dry Ash Free – an abbreviation.

Damper Mechanism
An apparatus for moving the combustion of gas flow resistance.

Making a fuel bed clean by removing fire residue.

De-Ashing Mechanism
A device for clearing firebed ash. The position of the bottom grate control can also be adapted in some appliances.

Deepening Plate or Front Firebars
A plate/grate to deter spills of ash and fuel, attached to the firebox entrance. It can also change the capacity of the firebox.

Direct Water System
Heating stored domestic water by circulating hot water from a boiler.

Draught Regulator
A gadget for controlling the draught in a flue by allowing air to flow downstream to the firebed.

The equation of total heat output against input, in any given test period, as a measurement ratio given as a percentage.

Power ability to be physically or mentally active.

The hinged plate often used in open fires to prevent combustion, or to slow it down, by covering up the fuel after moving the device.

Energy in heat, emitted quickly, usually as a result of fuel oxidation and leaving a visible light.

A surround set-up for the background of an open fire, which is made of brick or concrete.

Slats used for burning fuel.

Fuel housed inside a fire box.

Firebox Combustion Chamber
The section of an appliance used for burning fuel.

Firebox Opening
Hollow in a firebox, used to fuel the appliance.

The small door in an appliance, which can be opened to refuel the firebed. It also allows for a view of the fire.

The structure built to safely host an indoors fire.

A shaft space inside a chimney built for the purpose of taking fire gases from the firebed to the outside atmosphere.

Flue Draught
The point of difference in measurement of static air pressures between the installation and flue gases.

Flue Gas Adaptor
A device for adapting the varieties in shapes and sizes of flue components.

Flue Gas Connector
A gadget which provides a passageway for flue gases from the appliance spigot into the flue of the chimney.

Flue Gas Mass Flow
Flue gas mass, sifted from the appliance per time unit.

Flue Gas Temperature
A point of temperature in the flue gas, which is measured in a specific section.

Flue Gases
Fire gas compounds that leave the appliance flue spigot and then drift to the flue gas connector.

Flue Loss Analysis
The industry method of analysing the performance of a heating appliance. An examination is done of both the chemical composition and temperature of displaced fire gases, to see how much is found in the flue. This calculation provides an estimate of the heat output and efficiency rate.

Flue Socket or Spigot
A connection point within an appliance, establishing contact with the flue gas connector, to let combustion products leave via the chimney flue.

The section of an appliance section taking gas from combustion to the flue spigot, from the firebox.

Fuel Hopper
A store for fire fuel within the appliance, used to feed the firebox.

Fuel Regulator
A device to regulate the size of firebed.

Fuel within the firebox.

Energy created by the movement of atoms and molecules, produced differently according to the material used. For example, radiation transmits its form through empty space. Conduction, by comparison, takes the process via solid matter.

Heat Input
An energy amount given from fuel to the appliance.

Heat Output
The amount of heat that can be used, which has emitted from the appliance.

House Coal
Coal, usually bituminous in Britain, used for domestic use.

Indirect Water System
A heated water set-up. It uses a primary heater to warm up retained domestic hot water. Hot water from the boiler is circulated to produce heat but without blending primary heating water with the stored hot water.

Integral Fuel Storage Container
An appliance area, which is restricted but stores fuel pre-burning, that’s not linked to the fuel charge area.

Kennel or Cannel
Bituminous coal which is finely grained, light to handle and generally clean. It is also virtually smokeless.

Fuel matter, similar to bituminous coal and peat, which is brown and soft to touch.

Masonry Heater or Stove
An enclosed room heater, which retains heat within a brick set-up. Best models only need an hour to provide 24 hours worth of heat.

Maximum Water Operating Pressure
The optimum point for water pressure, when an appliance is safe to use.

An appliance which can burn both wood and mineral-sourced fuels.

Nominal Heat Output
The heat output overall from an appliance, as stated by the manufacturer under test conditions, using the appropriate fuel.

Operating Tool
The utensil provided with the appliance for controlling components which are hot, transportable or needed for adjusting the fire burn process.

Peat or Turf
Coal still at an early stage of composition, which is wooden and partly decomposed over an approx 1,000-year period.

Petroleum Coke or Pet Coke
Solid fuel made of petroleum residue, which burns powerfully. The intensity of the burning process tends to bring high levels of sulphuric acid to a local atmosphere. It can also cause havoc in appliances.

Primary Air
Combustion air, routed via a fuel bed.

Organic substances created by the partial burning of wood.

Chemical compound decomposition caused by heat; such as the lack of oxygen affecting organic materials. Carbonization is the result of complete pyrolysis, which leaves only carbon residue.

Thermometers designed to specifically record high temperatures. An optical pyrometer is such a type, which examines light conditions of an object to estimate the temperature – if that object is too hot to touch.

Energy emitted from a nuclear reaction and/or light or heat, which is invisible. The energy is transmitted with no intermediary required and ebbs away, depending on the distance involved.

Recommended Fuel
Fuel meeting commercial quality standards, which is recommended by the appliance manufacturer.

Recovery Capability
The capability of a fire to reignite previously burnt fuel, without support and in a set time scale.

Refueling Interval
The time period to sustain a fire with a single load of fuel.

Remainder of a fire within an appliance ashpit, such as ashes.

Riddling Mechanism or Riddler
The utensil for provoking the firebed and knocking away any ash.

The British Standards official description for ‘stove’.

Secondary Air
Air flow supporting gas combustion as it leaves the fuel bed.

Powdery waste coal.

Slow Combustion Heat Output
Heating level reached while slow burning under set conditions.

An appliance’s low rate burning performance, without more fuel or other help, within a minimal time period – so the firebed can be used again.

Solid particles suspended in fire gas.

Solid Fuel
Fuel substance which is solid such as wood parts, peat briquettes and coal.

Solid Mineral Fuel
Lignite, coal, coke and related fuels.

Heating level given by convection and radiation into a nearby room.

Apparatus altering the route for heating gas or the combustion (cross section) air opening needed for ignition.

Minimum changes in the measurement of values within a consistent time period.

An appliance heating a singular space: its own area (a cooking stove) or a nearby room (heating stove). The word hails from ‘stofa’ in Old English, meaning an enclosed area.

Test Fuel
Fuel type for testing appliances, which meets commercial quality standards.

An automatic device for changing the cross-sectional space for a combustion air inlet, which is sensitive to temperature changes.

Total Heat Output
The ongoing amount of heat still useable from an appliance.

Type Test Pressure
A form of pressure affecting every waterway of a test appliance.

The ratio of heat-output-to-water provided during a particular testing period.

Wood Powder
White powder produced by burning wood, similar to ash, which is flammable. High levels of wood powder indicates a fire set-up has a faulty design.

Working Surfaces
Appliance surfaces that transfer heat to a nearby atmosphere. A heating boiler with a flue gas connector has working surfaces in all of its exterior surfaces, according to EN standards. This is due to the design of heat transference to the area where the appliance is located.