Glossary Of Terms

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Air Set Refractory Mortar
Refractory mortar that begins to set on contact with air.
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Aluminium oxide
Al2O3 is an amphoteric oxide of aluminium, with a high melting point. Extremely abrasive at 9 on the Mohs scale. It is derived from Bauxite. Corundum is crystalline aluminium oxide.
As a general rule, the higher the percentage of aluminium oxide in a refractory brick, the higher its temperature rating.
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Bag Walls
The side walls of the secondary combustion chamber over which flow the gases as they leave the chamber and enter the side channels.
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Ball Clay
Fine grained plastic sedimentary clay rich in Kaolin Extracted in cubes that became rounded during transport to the surface. Relatively scarce, deposits are found in England and NE USA. First used in modern times for making tobacco pipes in the mid 17th century.
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Bottom Up Burn
Name used to describe the traditional fire laying technique in which the paper and kindling are layed first followed by the medium and then large wood. The fire is lit from bellow and burns vigorously upwards.
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Bypass Channel
A mechanical device used to divert the flue gases from the heater directly into the chimney. Usually located between the secondary combustion chamber and the chimney, or between a manifold and chimney when used to by-pass a bench. The principle function of a bypass is to establish a draw before engaging a portion of extended smoke path.
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Capping Slab
The castable refractory slab or slabs which close the top of the refractory core.
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Castable Refractory Concrete
Heat resistant concrete that can be pre cast to form modules to be used in the construction of a refractory core.
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Ceramic wool
Ceramic Blanket
High temperature woven ceramic fibre blanket, used as an expansion and smoke gasket.
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Chimney Cap
Cap, usually in concrete used to close the chimney top around the tile, and to protect the masonry of the chimney top from weather.
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Chimney connection
The point at which the heaters smoke path is connected to its chimney.
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Chimney hat
Installed over the flue tile on the chimney top to prevent rain falling directly into the flue.
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Chimney Shut off Damper
A mechanical device ,located in the chimney, used to close the smoke path after combustion. Also used to control the combustion by restricting the smoke path.
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Chimney top damper
A chimney cap that also acts as a shut off damper, closing the smoke path on the chimney top. Usually operated by cable from inside the dwelling.
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Clay Mortar
Mortar used specifically in stove and oven building. Typical mix is one fatty clay to 5 sand.
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Combustion Efficiency
The efficiency of both primary and secondary combustion. Not the efficiency of any one appliance. \
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Common Mortar
Type N Mortar
The mortar generally used for the laying of a heaters façade and masonry chimney.
1 Portland Cement: 1 lime: 6 sand.
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A course of masonry that is layed off plumb from the course below.
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Corbeled arch
False arch
A way of closing a narrow opening by corbeling in from each side until the two corbeled portions of wall meet and support each other.
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Curing Fires
A series of small fires lit immediately after the heater has been completed. These fires, gradually increasing in size are intended to dry the heater slowly, thus avoiding trapped water having a mechanical action on the materials.
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Direct Oven
Black Oven
Upper chamber oven having its bake chamber as part of the smoke path. Secondary combustion taking place within the bake chamber.
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Down Draught
The name given to a masonry stove which is connected to its chimney at the bottom, i.e. floor level.
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Expansion Gasket
Expansion Joint
Gasket usually, but not necessarily, of fireproof material, placed between two materials with a different expansion coefficient. Or two similar materials, with a different expansion rate against time.
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A single wythe masonry skin, enclosing a refractory core providing the heater's double skin. It can consist of any standard dense masonry material.
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Finnish Fire place
Finnish form for the Finnish Contra-Flow masonry heater.
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Finnish style cookstove
Masonry cook stove
Masonry cook stove typical of those used in Finland and Scandinavia. Achieving only partial secondary combustion, a masonry cookstove is completely independent of a masonry heater.
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Fire Box
Primary Combustion Chamber
Chamber in which the fire is layed, and in which primary combustion takes place. Accessed by the fire box loading door.
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Fire Tube
Area of the core directly above the fire box where secondary combustion takes place. Found in cores with an undefined throat and upper chamber. Unlike the upper chamber the fire tube does not rely upon compression and expansion of the gases to promote secondary combustion.
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Flue tile
Lining tile inserted into a section of masonry chimney to bake the chimney double skinned.
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Fly Ash
Fine particles of ash that are drawn through the smoke path, often accumulating on its horizontal surfaces.
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Free Floating
A module that is not physically held in place by mortar or masonry, is said to be free floating.
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Free Silica
Suspended Crystalline Silica
Fine crystals of silica suspended in the atmosphere in the form dust. Caused by the working of silica containing products. A general and specific safety hazard for the Mason.
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Fire sand
A raw refractory material, high in silica and alumina. Having a relatively coarse particle range, grog is usually light and porous.
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Local name for the German version of the masonry heater. Built by an Hafner or Ofensetzer.
The groundofen is distinguished by its lack of grate, and it usualy being built directly onto the floor.
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Barely visible cracks in masonry, no thicker than a human hair.
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Hand Built Refractory Core
Custom built core
Site built refractory core. Usually built by a qualified specialist entirely from refractory brick.
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Heat exchange channels
Side channels
The heat exchange channels that run down each side of the core, separated from the core by a heat resistant gasket.
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Heat set refractory mortar
Refractory mortar that sets only on contact with heat. Less common that Air Set Mortar.
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Heated Bench
Transmission tunnel
Portion of extended, horizontal, smoke path deviating from the heater, before re-joining the chimney.
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High Temperature Cement HTC
Refractory Mortar
The pre mixed water or paste used to lay refractory brick. In France the product referred to as Mortier Refractaire is not the product referred to here and has no use in the construction of a refractory core.
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The name given by the Romans to their system of heating bath rooms by running flue gasses through a series of masonry heat exchange channels, usually in a floor. Though never or rarely achieving secondary combustion these heating systems are considered to be the first recorded examples of the deliberate use of thermal retention within masonry mass. Evidence of their use can be found throught the former Roman world.
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Indirect Oven
White Oven
Oven located in the upper chamber but being entirely closed to the smoke path. Secondary combustion takes place below, above, behind, and to the sides of the bake chamber.
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J –Loop
An adaption of a contraflow stove where the gases descend one side channel, and return up through the other side channel before exiting at the top of the stove. As opposed to the gases descending both side channels and exiting at the bottom.
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Local name for the Swedish version of the Masonry Heater.
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Local name for the Swedish version of the Masonry Heater.
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Manchurian version of the Ondol.
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Lime Mortar
Mortar used for general masonry work until the beginning of the 20th century. Usually one portion of lime to 3 sand.
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A horizontal beam used to traverse an opening. Can be of stone, iron, refractory concrete, or commune concrete.
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Load Relieving Lintel
A lintel used to transfer compressive force, away from a potential week point.
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The widened area of the smoke path directly beneath each side channel. There are three manifolds in a contra-flow core; left and right side manifolds and a rear manifold running beneath the back portions of the fire box.
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Mechanical bridge
A solid contact between two otherwise separate, rigid materials, causing the possibility of one having a mechanical action on the other due to thermal expansion.
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Korean domestic version of the hypocaust having the form of a ceramic sitting or sleeping platform. The Ondol is still used in Korea today though most are fired with oil or gas.
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Over Air
The name given to the method of delivery for primary combustion air, in which it is directed onto the wood load either laterally or from above. The distinction being that no air rises through a grate beneath the wood load.
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Local name of the Polish version of the masonry heater. Built by the Dzrune
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Russian name for the Russian domestic masonry oven. Built by a Pich Nik
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Prefabricated Masonry Heater
Heater completely prefabricated, i.e. core and facing.
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Prefabricated Refractory Core
Pre-Fab Kit
Refractory core that is entirely factory made, consisting usually of castable refractory concrete modules. Can be installed by non specialised mason.
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Primary Combustion Air
Air drawn in to the fire box, usually from an intake in the facing below the fire box door, which feeds the primary combustion of the wood load. Primary air makes up most of the flow in the smoke path.
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Priming fires
The small fire lit when the heater is being used from a cold start. These fires bring the heater slowly up to operating temperature, avoiding thermal shock.
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Refractory core
The interior portions of a masonry heater, which enclose the smoke path. Usually, though not necessarily, made from refractory brick or concrete.
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Russian Stove
A general name user to describe stoves built throught the former Soviet empire. Built by a Pechnik.
Local names include petch, pich, grubca,gruba.
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Secondary Combustion.
Double Combustion
Ignition and combustion of unburnt gases, during, and immediately after primary combustion.
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Secondary Combustion Air
Air drawn into the fire box, usually through an intake in the fire box door. This air bypasses the primary combustion, travels across the fire box ceiling and mixes with the smoke and flame to nourish secondary combustion.
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Secondary Combustion Chamber
Expansion Chamber
Upper Chamber
Chamber above the fire box, connected to it by the throat, where secondary combustion of the flue gases takes place, before the gases flow into the side channels.
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Secondary Combustion Chamber Oven
Upper Chamber Oven
Auxiliary oven taking up space within the heaters upper chamber. Having a loading opening on the front or rear face of the heater.
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See Through Heater
A heater with a firebox loading opening on both front and rear face. Generally considered to be slightly less efficient than a heater with only one fire box loading opening.
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Semi prefabricated refractory core
Refractory core containing some precast modules of refractory concrete, but necessitating the laying of some fire brick during their assembly.
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Brick that are layed face down i.e. on edge, rather than bed down.
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An incurable lung disease contracted du to the long term prolonged exposure to Suspended crystalline silica.. Note In France it is said "Une bonne fumist est mort a 50 année".
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Smoke gasket
Gasket of fire proof material used to inhibit the passage of smoke from one portion of the heater to an other.
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Smoke Hood
Hood or funnel in masonry or metal, used to draw smoke together towards and into a chimney. Found on the front of direct fired ovens.
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Smoke Path
The path taken by the draw of the system through its self. Beginning at the primary air intake door and ending at the top of the chimney.
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Soba de Terracota
Local name for the Romanian version of the masonry heater. Built by a Sobar.
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Sodium Silicate
Actual Name: Sodium meta-silicate, Na2SiO3
Water Glass.
Used as a bonder (hardener) in refractory mortars. Available in dry or liquid form.
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Soot Doors
Clean Outs
Openings giving access to the manifolds. Usually fitted with cast iron doors
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The disintegration and loss of the exposed surfaces of a material.
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Thermal Break
A layer of insulating material placed between two dense conductive materials with the intention of impeding thermal transmission.
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Thermal Bridge
A solid bridge allowing the conduction of heat from one dense material to another.
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Thermal cycling
The cyclic rise and fall in temperature which occurs during and after each fire.
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Thermal Shock
The destructive action caused on a material that is brought up to temperature too fast, or unevenly. The main enemy to the longevity of the masonry heater.
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Thermal Stress
The detrimental effect of a material that is saturated, accumulating heat faster than it can transfer heat, resulting in cracking and warping.
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The natural tendency for hot air to rise as it is displaced by cold air.
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Point at which the fire box ceiling narrows, compressing the gases. Usually precedes the upper expansion chamber
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Top Down Burn
Name used to describe the manner in which a fire is layed, with the large wood on the bottom, medium wood above that and finally the paper and kindling layed on top. The fire is lit at the top and burns slowly from the top down.
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Total Efficiency
The total efficiency of the appliance, of which combustion efficiency is on a part.
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Transfer Efficiency
The measure of a material’s capacity of thermal transfer over time.
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Under Air
The name used to describe the manner in which primary combustion air enters the fire box via a grate in the fire box floor.
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Up Draught
The name given to a masonry stove which is connected to it’s chimney at the top of the stove
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The Polish name for stove builder.
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Last Updated: 11 September 2017