Masonry heater

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A classic Scandinavian style round ceramic stove which fits in the corner of a room. Malingsbo herrgard 9.jpg
A classic Scandinavian style round ceramic stove which fits in the corner of a room.

A masonry heater (also called a masonry stove ) is a device for warming an interior space through radiant heating, by capturing the heat from periodic burning of fuel (usually wood), and then radiating the heat at a fairly constant temperature for a long period. Masonry heaters covered in tile are called cocklestoves (also tile stoves or ceramic stoves). The technology has existed in different forms, from back into the Neoglacial and Neolithic periods. Archaeological digs have revealed excavations of ancient inhabitants utilizing hot smoke from fires in their subterranean dwellings, to radiate into the living spaces. These early forms have evolved into modern systems.

Stove enclosed heated space

A stove is an enclosed space in which fuel is burned to heat either the space in which the stove is situated, or items placed on the heated stove.

Wood Fibrous material from trees or other plants

Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic material, a natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin that resists compression. Wood is sometimes defined as only the secondary xylem in the stems of trees, or it is defined more broadly to include the same type of tissue elsewhere such as in the roots of trees or shrubs. In a living tree it performs a support function, enabling woody plants to grow large or to stand up by themselves. It also conveys water and nutrients between the leaves, other growing tissues, and the roots. Wood may also refer to other plant materials with comparable properties, and to material engineered from wood, or wood chips or fiber.

The Neolithic, the final division of the Stone Age, began about 12,000 years ago when the first developments of farming appeared in the Epipalaeolithic Near East, and later in other parts of the world. The division lasted until the transitional period of the Chalcolithic from about 6,500 years ago, marked by the development of metallurgy, leading up to the Bronze Age and Iron Age. In Northern Europe, the Neolithic lasted until about 1700 BC, while in China it extended until 1200 BC. Other parts of the world remained broadly in the Neolithic stage of development until European contact.


Evidence found from 5,000 B.C. of massive blocks of masonry used to retain heat foreshadowed early forms of fire hearths that were used as multifunctional heating sources. Later evolutions came in the Roman hypocaust and Austro-German cocklestove (Kachelofen, literally "tile stove", or Steinofen, "stone stove"), using the smoke and exhaust of a single fire. In Eastern and Northern Europe and North Asia, these cocklestoves evolved in many different forms and names: for example the Russian stove (Russian : Русская печь ), the Finnish stove (in Finnish: pystyuuni or kaakeliuuni, "tile oven") and the Swedish stove (in Swedish: kakelugn, "tile stove" or "contra-flow stove") associated with Carl Johan Cronstedt. The Chinese developed the same principle into their Kang bed-stove. The masonry heater has gained renewed domestic popularity recently because of its heating efficiency.

<i>Kang</i> bed-stove Traditional long platform

The kang is a traditional long platform for general living, working, entertaining and sleeping used in the northern part of China, where the winter climate is cold. It is made of bricks or other forms of fired clay and more recently of concrete in some locations.

Hypocaust Ancient Roman system of underfloor heating

A hypocaust is a system of central heating in a building that produces and circulates hot air below the floor of a room, and may also warm the walls with a series of pipes through which the hot air passes. This air can warm the upper floors as well. The word derives from the Ancient Greek hypo meaning "under" and caust-, meaning "burnt". The earliest reference to such a system suggests that the temple of Ephesus in 350 BC was heated in this manner, although Vitruvius attributes its invention to Sergius Orata in c.80 BC. Its invention improved the hygiene and living conditions of citizens, and was a forerunner of modern central heating.

Smoke mass of airborne particulates and gases

Smoke is a collection of airborne solid and liquid particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwanted by-product of fires, but may also be used for pest control (fumigation), communication, defensive and offensive capabilities in the military, cooking, or smoking. It is used in rituals where incense, sage, or resin is burned to produce a smell for spiritual or magical purposes. It can be a flavoring agent and preservative for various foodstuffs.

A masonry heater is defined by ASTM International as "a vented heating system of predominantly masonry construction having a mass of at least 800 kg (1760 lbs), excluding the chimney and masonry heater base. In particular, a masonry heater is designed specifically to capture and store a substantial portion of the heat energy from a solid fuel fire in the mass of the masonry heater through internal heat exchange flue channels, enable a charge of solid fuel mixed with an adequate amount of air to burn rapidly and more completely at high temperatures in order to reduce emission of unburned hydrocarbons, and be constructed of sufficient mass and surface area such that under normal operating conditions, the external surface temperature of the masonry heater (except in the region immediately surrounding the fuel loading door(s)), does not exceed 110°C (230°F)." [1]

ASTM International standards organization

ASTM International, formerly known as American Society for Testing and Materials, is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services. Some 12,575 ASTM voluntary consensus standards operate globally. The organization's headquarters is in West Conshohocken, Pennsylvania, about 5 mi (8.0 km) northwest of Philadelphia.


A cocklestove used for central heating, built around 1959. Kachelofen als Warmluftzentralheizung.jpg
A cocklestove used for central heating, built around 1959.

The stove is made of masonry such as brick (firebrick), soapstone, tile, stone, stucco, or a combination of materials, rather than steel or cast iron. It is freestanding, and usually requires special support to bear its weight. It consists of a firebox and heat-exchange channels or partitions that provide additional surface area. These absorb heat from the hot exhaust gases before the gases exit into the chimney. The fire in a masonry heater burns much hotter than in a metal stove. Very hot fires reduce emissions significantly. When not being fired, the connection from the masonry heater to the chimney sometimes has a damper to prevent heat from escaping up the chimney; the heat is then radiated from the masonry.

Masonry The building of structures from individual units of stone, brick, or block

Masonry is the building of structures from individual units, which are often laid in and bound together by mortar; the term masonry can also refer to the units themselves. The common materials of masonry construction are brick, building stone such as marble, granite, and limestone, cast stone, concrete block, glass block, and adobe. Masonry is generally a highly durable form of construction. However, the materials used, the quality of the mortar and workmanship, and the pattern in which the units are assembled can substantially affect the durability of the overall masonry construction. A person who constructs masonry is called a mason or bricklayer. These are both classified as construction trades.

Chimney structure that provides ventilation for exhausting the hot or toxic flue gases, aerosols and smokes produced by a boiler, stove, furnace or fireplace inside a building to the outside atmosphere

A chimney is an architectural ventilation structure made of masonry, clay or metal that isolates hot toxic exhaust gases or smoke produced by a boiler, stove, furnace, incinerator or fireplace from human living areas. Chimneys are typically vertical, or as near as possible to vertical, to ensure that the gases flow smoothly, drawing air into the combustion in what is known as the stack, or chimney effect. The space inside a chimney is called the flue. Chimneys are adjacent to large industrial refineries, fossil fuel combustion facilities or part of buildings, steam locomotives and ships.

Masonry takes longer to heat than metal; but once warm, the heater will radiate this heat over a much longer period of time and at a much lower temperature than a metal stove would use (the metal is hot only when there is a fire burning inside the stove and for a short time thereafter). A masonry heater is warmed by fires that burn for a short time; it is mostly the heat stored by the heater's mass that heats the living space. Both in Europe and in America seating and even beds are occasionally built adjoining the masonry stove; this is possible because the heater's exterior surfaces are cool enough to touch safely. This cycle of short firings and long periods of heat-release makes a masonry heater a much more convenient option for actually heating a house with wood, than a metal wood stove. Masonry stoves can release heat from anywhere up to 36 hours after the fire has gone out (the larger the thermal mass the more heat the appliance can retain). This means that a householder might typically light a fire in the evening on returning home. In a more modern masonry heater with a glass door, this means that they can enjoy the fire during the evening. But overnight and throughout the next day when the fire is no longer alight the heater will still be warming the house, ready for the cycle to start again next evening. Compare this to a metal stove which is often either too hot or too cold (unlit) and the requirement for the owner to be present to load with logs at regular intervals and the benefits should be clear.

Heat stress is a major concern during the construction of masonry heaters. Differences in temperature inside the masonry core of the heater can result in differential expansion. A skilled heater mason knows how to provide for this stress when designing and constructing the heater, thereby preventing uneven expansion from causing cracking in the exterior. There are two general ways this concern is addressed. One is to incorporate a gap between the inner core of the heater and its outer "skin." The other is to build a more monolithic design with post-tension aspects to mechanically compensate for expansion and contraction. Both methods are used with success. [2]

Brick by Brick Masonry heaters take a long time (from 5 hours up to two days) to get up to the right temperature and so are not always practical for taking the chill off a single cool evening or morning. American Masonry Heaters has their own blend of refractory which allows the heater and surrounding area to heat up in an hour or two.( Envirotech Line is tested and approved by the EPA, been around for 30 years) [ citation needed ] The speed with which a masonry heater achieves the right temperature is called its responsiveness. [ citation needed ]Responsiveness is determined by the specific thickness and characteristics of the materials used in its construction. Very responsive heaters warm up faster and are good for quicker adjustments to indoor temperature. Less responsive heaters take longer to warm, but they are well-suited for long periods of cold weather because they store heat so well and provide dependable, even heat all day and night. [3] Because the radiant heat is given off at a low level a masonry heater is not likely to overheat a home the way a metal stove might in warmer parts of the year like fall or spring.


Cocklestove by Joseph Effner, Schleissheim Palace (ca. 1720) Effner-Ofen 1.jpg
Cocklestove by Joseph Effner, Schleissheim Palace (ca. 1720)

The cocklestove (German : Kachelofen, "tile stove") design, a relatively large home heater surrounded with ceramic tile, has existed for at least five centuries. During the Renaissance period, the builders of cocklestoves were part of a distinct trade and were called hafnermeister. A cocklestove uses a maze-like passage created out of firebrick to release gases and smoke from the wood fire slowly, allowing the firebrick to retain as much heat as possible from the gases and smoke. The ceramic tile surrounding the cocklestove also acts as insulation to retain heat. Cocklestoves were carefully designed so that the minimum amount of heat would escape, only as much as needed to warm the flue to maintain a proper air draught. The firebrick used in cocklestove construction holds 80% more heat than ferrous metals such as cast iron, while its heat conductivity is 1/45 that of iron or steel. [4] A cocklestove is efficient enough to warm a house for up to 6 to 12 hours after the fire has stopped burning. [5]

Russian stove

Russian stove, another typical masonry heater, evolved in the Russia in 15th century, after the brick flue was added to the traditional black-fired fireplace, which lacked the smokestack and vented directly into the room. The addition of the flue allowed for the better heat utilisation by passing the smoke and gases through the brick labyrinth called kolenya (коленья. "knees" or "bends") before allowing it into the smokestack. The large thermal mass of these bends captured the heat, slowly releasing it afterwards. The typical Russian stove is a large, generally cuboid mass of masonry, usually weighing around 1-2 tons, built in the center of a traditional izba log hut, covered in stucco and carefully whitewashed.[ citation needed ]

Most Russian stoves consist of a massive firebrick hearth, often large enough for a grown man to fit into, with a flue continuing into a maze-like heat exchanger built of a normal brick, usually with a built-in stove for cooking, which sometimes used a secondary fireplace to quickly cook foods without heating the whole affair; all covered with an outer brick shell, normally with a pedestal for a kitchen work and beds built into it. The stove was usually constructed by one of the house's walls, or, in the larger, multi-room houses, into one of the walls, in which case the room without the fireplace, and thus the smoke, but heated by the brick side of the stove, was called svetlitsa ("light one") and used as a living room, while the other was used as a kitchen. The small spaces left behind the stove and under its log foundation were called zapechye ("behind the stove") and podpechye ("under the stove"), and used as dry, warm storage. These were stereotyped as dwellings of the domovoi. The whole trade of stovebuilders (pechniki) developed, and given the difficulties of proper stove construction and skill involved, these were seen as an influential bunch not to be trifled with, as an offended pechnik had numerous ways to get back at the employer.[ citation needed ]

Fuel sources

Modern masonry heater Modern Masonry Fireplace.jpeg
Modern masonry heater

These heaters are primarily fired by wood, and those fires are meant to burn hot and quickly (never damped down, as is often the case with standard wood stoves). They are not burned continuously. This method of heating may have been a reaction to the dwindling resource of wood before the advent of coal and other mineral energy sources. Open hearth fireplaces were an important source of light, as well as heat, and with an "unlimited" supply of wood to fire them, there is no incentive to increase the efficiency of their heat output, which is rather poor. However, once firewood became a scarcer resource, fireplace builders began to enclose the firebox to capture as much heat as possible.

Since masonry heaters burn hot and fast, they can accept any dry, split (usually three to five inches in diameter) wood. In some areas of central and eastern Europe, these heaters are sometimes effectively fired using grass, straw, and hay. It is also common in eastern Europe to modify these efficient heaters so that they are connected to the gas network and are fueled with gas. Some modern models incorporate electric heating elements connected to timers. These are used only as a backup heat source during periods when the structure will be left unattended for long duration in winter (and therefore with no one to build a new fire in the heater each day or as needed) to prevent the structure from freezing.

Modern development

Some contemporary masonry heaters don't have a ceramic-tile exterior. Instead, the refractory bricks are covered by a heat-resistant kind of plaster. A glass door allows you to see the burning fire. As in the past once the firewood has burned, the warmed mass of the stove continues to radiate heat, but the size of the flue passages of modern masonry heaters are more exactly calculated than they used to be; this is done to provide increased efficiency and output and use less wood.

Some masonry heaters (such as the Tulikivi lineup) are made completely out of soapstone, whereas traditional masonry heaters are made from brick, stone, or tile. Soapstone is a relatively new development due to excellent heat retention (higher than almost anything but firebrick) and the low surface temps when in operation, which prevents burns.

See also

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Furnace device used for heating in industry

A furnace is a device used for high-temperature heating. The name derives from Latin word fornax, which means oven. The heat energy to fuel a furnace may be supplied directly by fuel combustion, by electricity such as the electric arc furnace, or through induction heating in induction furnaces.

Franklin stove

The Franklin stove is a metal-lined fireplace named after Benjamin Franklin, who invented it in 1741. It had a hollow baffle near the rear and relied on an "inverted siphon" to draw the fire's hot fumes around the baffle. It was intended to produce more heat and less smoke than an ordinary open fireplace, but it achieved few sales until it was improved by David Rittenhouse. It is also known as a "circulating stove" or the "Pennsylvania fireplace".

Wood fuel

Wood fuel is a fuel, such as firewood, charcoal, chips, sheets, pellets, and sawdust. The particular form used depends upon factors such as source, quantity, quality and application. In many areas, wood is the most easily available form of fuel, requiring no tools in the case of picking up dead wood, or few tools, although as in any industry, specialized tools, such as skidders and hydraulic wood splitters, have been developed to mechanize production. Sawmill waste and construction industry by-products also include various forms of lumber tailings. The discovery of how to make fire for the purpose of burning wood is regarded as one of humanity's most important advances. The use of wood as a fuel source for heating is much older than civilization and is assumed to have been used by Neanderthals. Today, burning of wood is the largest use of energy derived from a solid fuel biomass. Wood fuel can be used for cooking and heating, and occasionally for fueling steam engines and steam turbines that generate electricity. Wood may be used indoors in a furnace, stove, or fireplace, or outdoors in furnace, campfire, or bonfire.

Kitchen stove kitchen appliance designed for the purpose of cooking food

A kitchen stove, often called simply a stove or a cooker, is a kitchen appliance designed for the purpose of cooking food. Kitchen stoves rely on the application of direct heat for the cooking process and may also contain an oven, used for baking. "Cookstoves" are heated by burning wood or charcoal; "gas stoves" are heated by gas; and "electric stoves" by electricity. A stove with a built-in cooktop is also called a range.

Fireplace device for firing solid fuels in residential buildings

A fireplace is a structure made of brick, stone or metal designed to contain a fire. Fireplaces are used for the relaxing ambiance they create and for heating a room. Modern fireplaces vary in heat efficiency, depending on the design.


Ondol or gudeul in Korean traditional architecture, is underfloor heating that uses direct heat transfer from wood smoke to heat the underside of a thick masonry floor. In modern usage it refers to any type of underfloor heating, or to a hotel or a sleeping room in Korean style.

Flue duct, pipe, or opening in a chimney for conveying exhaust gases from a fireplace, furnace, water heater, boiler, or generator to the outdoors; space inside a chimney

A flue is a duct, pipe, or opening in a chimney for conveying exhaust gases from a fireplace, furnace, water heater, boiler, or generator to the outdoors. Historically the term flue meant the chimney itself. In the United States, they are also known as vents for boilers and as breeching for water heaters and modern furnaces. They usually operate by buoyancy, also known as the stack effect, or the combustion products may be 'induced' via a blower. As combustion products contain carbon monoxide and other dangerous compounds, proper 'draft', and admission of replacement air is imperative. Building codes, and other standards, regulate their materials, design, and installation.

Pellet stove

A pellet stove is a stove that burns compressed wood or biomass pellets to create a source of heat for residential and sometimes industrial spaces. By steadily feeding fuel from a storage container (hopper) into a burn pot area, it produces a constant flame that requires little to no physical adjustments. Today's central heating systems operated with wood pellets as a renewable energy source can reach an efficiency factor of more than 90%.

Space heater device which heats a single small area

A space heater is a device used to heat a single, small area; central heating is used to heat many connected areas, such as the rooms of a house. Space heaters are powered by electricity or a burnable fuel, such as natural gas, propane, fuel oil, or wood pellets. Portable space heaters are usually electric, because a permanent exhaust is needed for heaters which burn fuel.

Chimney fire fire within a chimney

A chimney fire is the combustion (burning) of residue deposits referred to as soot or creosote, on the inner surfaces of chimney tiles, flue liners, stove pipes, etc.

Wood-burning stove type of stove

A wood-burning stove is a heating appliance capable of burning wood fuel and wood-derived biomass fuel, such as sawdust bricks. Generally the appliance consists of a solid metal closed firebox, often lined by fire brick, and one or more air controls. The first wood-burning stove was patented in Strasbourg in 1557, two centuries before the Industrial Revolution, which would make iron an inexpensive and common material, so such stoves were high end consumer items and only gradually spread in use.

Carl Johan Cronstedt was a Swedish architect, inventor, count, noble, civil servant, scientist and bibliophile.

Russian stove

A Russian stove is a unique type of masonry stove that first appeared in the 15th century. It is used both for cooking and domestic heating in traditional Russian, Ukrainian and Belarusian households. The Russian stove burns firewood or wood manufacturing waste.

Rocket mass heater

A rocket mass heater is a space heating system developed from the rocket stove, a type of efficient wood-burning stove, and the masonry heater. Its fundamental characteristics are an insulated combustion chamber where fuel is burned with high efficiency at extremely high temperatures, and a large thermal mass in contact with the exhaust gases which absorbs most of the generated heat before the gases are released to the atmosphere. According to various reports a rocket mass heater can reduce fuel consumption by 80 - 90% compared to "conventional" stoves.

A direct vent fireplace is a prefabricated metal fireplace that employs a direct-vent combustion system. "Direct vent" refers to a sealed-combustion system in which air for combustion is drawn from the outdoors, and waste combustion gasses are exhausted to the outdoors. "Direct vent" does not simply mean that all gasses from combustion are vented to the exterior of the structure in which it is installed.


  1. Masonry Heaters: Designing, Building, and Living with a Piece of the Sun by Ken Matesz (Chelsea Green Publishing Co., 2010), p. xv. ISBN   978-1-60358-213-1
  2. Masonry Heaters: Designing, Building, and Living with a Piece of the Sun by Ken Matesz (Chelsea Green Publishing Co., 2010), p. 172. ISBN   978-1-60358-213-1
  3. Masonry Heaters: Designing, Building, and Living with a Piece of the Sun by Ken Matesz (Chelsea Green Publishing Co., 2010), p. 131. ISBN   978-1-60358-213-1
  4. Schneider, Jason (January 1979). Tile stoves: efficient and elegant wood burners (Vol. 214, No. 1 ed.). Popular Science, Bonnier Corporation. p. 98. ISSN   0161-7370.
  5. Schneider, Jason (January 1979). Tile stoves: efficient and elegant wood burners (Vol. 214, No. 1 ed.). Popular Science, Bonnier Corporation. p. 100. ISSN   0161-7370.

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