A wood burning stove (or wood burner or log burner in the United Kingdom) is a heating device capable of burning fuel wood and fuel wood biomass, such as sawdust bricks. Generally this tool consists of solid metal (usually cast iron or steel) covered with fire, often coated by fire bricks, and one or more air controls (which can be operated manually or automatically depending on the stove). The first wood burning stove was patented in Strasbourg in 1557, two centuries before the Industrial Revolution, which would make iron a cheap and common material, so such a furnace was a high-end consumer good and only gradually spread use.
The stove is connected with a stove pipe vent to a suitable chimney, which will be filled with hot combustion gases once the fuel is turned on. The chimney or exhaust gas must be hotter than the outside temperature to ensure the combustion gas is pulled out of the fire chamber and up into the chimney.
Video Wood-burning stove
Operation
Air Supply
Keeping the air flowing right through the wood burning stove is essential for safe and efficient stove operation. Fresh air needs to enter the fire box to provide oxygen for the fire; when the fire burns, smoke must be allowed to rise through the stove pipe, and out through the chimney. To adjust the airflow, there may be silencer devices built into the stove, chimney, and stove pipe.
By opening or closing the dampers, airflow can be increased or lowered, which can fan a fire in a fire box, or "muffle" by limiting airflow and reducing fire. Silencers are usually accessible by turning the knob or handle attached to the silencer. Some stoves adjust their own airflow using mechanical or electronic thermostatic devices.
The highest heating efficiency in closed equipment can be achieved by controlling various air supply to the stove (operating the air control properly). In a modern furnace, the owner's manual provides a documented procedure. Full open air control can lead to more heat being sent straight up the chimney rather than into the room (which reduces efficiency). The biggest problem with allowing full open air control on many stoves is "overfiring". Overfiring is caused when too much heat is generated inside the fire chamber, which will cause warping, bending and general damage to the stove and its internal components. Different stoves have different numbers and types of air controls.
Modern building techniques have created a more airtight home, forcing many stove manufacturers to design their stoves to permit the introduction of air from outside. The outside air can improve the overall efficiency of the stove as a heater by drawing cold combustion air directly from outside, instead of drawing hot air from the room where the stove is located. Many modern stoves can optionally use external air intake. Many manufacturers supply the necessary parts in the form of kits (Outer Air Kit, or OAK). When considering an outside air kit, it is important to know that the air must enter from below the stove level. For example, a basement stove may be unsafe using an outside air kit. This prevents the reversal of ventilation in which a very hot smoke gas is exhausted through an air intake pipe (usually PVC), which may cause a structural fire and/or hot gas flame to be released into the structure.
Maps Wood-burning stove
Fuel
Hardwood or softwood
Firewood is usually measured in English-speaking countries in a number of so-called cables, measuring 128 cubic feet (3.6 m 3 ) ( stack of 'solid' arranged 4 'high x 4' deep x 8 'wide). Firewood can be purchased by cable, or with a small portion of the cord. The term "face cable" is commonly used to describe various volumes of wood. Nominally means 4 'x 8' x the third measurement is not specified, but the term is often used by unscrupulous sellers to mean varying amounts. Experienced firewood buyers and honest firewood sellers â € <â € When buying, cutting, or collecting firewood, it's good to know the difference between hardwood and softwood. Both hardwood and softwood have the same energy content as the mass, but not by volume. In other words, a piece of hardwood will usually be heavier and have more energy available than a piece of softwood of the same size. Hardwood, derived from trees such as oak and ash, can burn at a slower rate, producing sustainable output. A lot of softwood comes from conifers, which are fast growing and can burn at a faster rate. This is one of the reasons why soft wood pellets (for pellet stoves) are very popular. The main advantage of hardwoods is that they tend to contain more potential energy than the same softwood volume, thereby increasing the amount of potential heat that can be stacked into one stoveload. Hardwood tends to form and maintain a layer of hot coal, which releases less heat for a long time. Hard wood is ideal for long, low burn, especially in stoves with poor ability to sustain low burns, or in mild weather when high heat output is not required. Softwood, on the other hand, tends to burn hot and fast with little coaling. They may leave fewer ashes than hardwood. Softwood is ideal for fast and hot burns. They produce excellent heat and do not fill the stove with embers, a problem that often happens to those who push their wood burning stove to get the maximum possible heat from them. Not all hardwoods have a higher potential energy content than all softwoods. Wood varies by species and even individual trees (trees with slow growth over the years will have a higher BTU content than trees with the same species and the same size of trees with several years of rapid growth). Osage orange, also known as hedge, is probably the highest BTU wood common in North America. A lot of softwood will season (dry) much faster than a lot of hardwood. For example, pine that has been cut, split, stacked and closed will usually be ready to burn within a year; oak is expected to take three years under the same conditions. Softwood mythology
Softwood is often said to be dangerous to burn because it creates a more dangerous creosote than hardwoods. This myth is pervasive in northeastern North America, where both types of wood are usually available. It is not common in the northwest, where full-time wood burners burn pine and spruce exclusively. A basic understanding of what creosote is and how it accumulates in your puff is all you need to break free from this dangerous untruth.
It is possible that this myth comes from ancient stoves and fireplaces. This "tool" does not require dried wood, and often does not accept it. As a result, they often experience very low smoke temperatures - usually in uninsulated chimneys as modern flues. The combination between low fire temperatures due to high water content in wood and low smoke temperatures due to lack of insulation causes high creumote accumulation. Burning wood that emits a lot of sparks (like pine) in an old fireplace or a stove will cause a spark to go straight into the chimney, which can cause a dangerous fire chimney if the chimney is coated with creosote.
A properly operated modern furnace does not cause this high creosote accumulation. While different wood species do contain different levels of volatile organic compounds, the difference is academic for wood burners. All forests produce creosot. All wood will cause creosote accumulation if it is burned incorrectly. What is called a dangerous forest like pine is actually safer than wood like oak, because wood will burn more hot and thus help keep cigar temperatures, and their quick spices will help ensure that new wood burners burn enough dry wood.
Moisture and creosote content
Dry wood produces more heat that can be used than wet wood, because the energy used to evaporate water from wood is lost to the chimney. The newly cut timber (known as green wood) has a high water content. Different wood species have different water content, which also varies from tree to tree. Burning fuel that mostly water uses a lot of burning energy to evaporate water. It produces a low fire temperature and a low chimney temperature.
Firewood with moisture content below 20 percent by weight can burn efficiently. This is the "free" water content absorbed in the wood fibers, and excludes chemically bound hydrogen and oxygen content. The water content can be reduced by outdoor air drying ("spice"), for a period of several months in the summer weather. Solar-powered furnaces or fuel combustion can speed up the drying process.
The most common process for removing excess moisture is called spice. Seasoning by drying wood air can take three years or more. The wood is dried in a closed structure that is well ventilated in the open air, or in a kiln.
All wood will release creosote vapors when burned. The modern stove will burn the vapor, either through secondary combustion directly or through the catalyst. Very few, if any, creosote that will escape the modern secondary combustion that operates well.
The escaped creosote may still be harmless. It leaves wood in the form of gas. It will not condense on surfaces above 250 degrees Fahrenheit. Modern fluids are isolated to help ensure that they do not fall below this temperature during normal furnace operations. The accumulation of creosote can be dangerous, because it is flammable and burning hot. If the chimney is coated with creosote and ignited, perhaps by a spark that rises into the chimney, it can cause a serious chimney fire that can cause a structural fire. This can be avoided by using modern and standard burners, burning dry wood, keeping your fire hot enough to maintain a chimney temperature of at least 250 degrees F at the top of the chimney, and proper chimney cleaning as needed.
Multi-fuel model
The design of multi-fuel stoves is common in UK, Ireland and Europe. They burn only solid fuels, including wood, wood pellets, coal and peat. They are usually made of steel or cast iron. Some models are also boiler stoves, with water tanks installed to provide hot water, and they can also be connected to the radiator to add heat to the house, although usually not as efficient as special wood boilers.
There is also a stove model that can switch from wood fuel to an oil or gas source installed at home to supply heat to a separate water boiler. Stoves ready for conversion to oil or gas in addition to wood fuel have been produced in North America and Europe since the early 20th century, and are still being produced. In some models, oil or gas can refuel the stove through a pipe connection that leads to the "burner pot" on the back of the firewood compartment on the stove.
Multi-fuel stoves are versatile, but they usually perform poorly compared to stoves designed to burn one specific fuel as best as they can.
Catalytic and non-catalytic stove
Modern wood stoves have a universal method of combustion secondary to burning unburned gases to improve efficiency and emissions. One of the most common methods is through a catalyst.
The catalytic wood stove will re-burn the gas from the fire box in steel or ceramic-coated matrix catalysts which allow the combustion of this gas to a much lower temperature than usual. This is why, among modern furnaces, the catalytic model tends to be much better at achieving the lower, even desired heat output in warmer weather.
Modern non-catalytic wood stoves will also reburn gas from a fire box, but require much higher temperatures for secondary combustion. No catalyst required. These models lose a great deal of efficiency at low burn rates, since they can not maintain secondary combustion, but can be highly efficient at higher temperatures that allow secondary combustion.
There is also a hybrid stove that uses catalytic and non-catalytic secondary combustion.
Stoves that do not use secondary combustion still exist, but are much less efficient than modern stoves due to lack of secondary combustion.
Rip the furnace
In a conventional furnace, when wood is added to hot flame, the pyrolysis process or destructive distillation begins. The evolved (or volatile) gas that burns on solid fuel. These are two different processes that occur in most solid fuel equipment. In obsolete stoves without secondary combustion, air should be received below and above the fuel to try to improve combustion and efficiency. The right balance is difficult to achieve in practice, and many obsolete wood burning stoves only recognize air over fuel as a simplification. Often volatiles are not completely burnt, resulting in energy losses, chimneys, and atmospheric pollution.
To overcome this, the pyrolyzing stove was developed. Both processes take place in a separate section of the stove with a controlled air supply separately. Most stoves designed to burn wood pellets fall into this category.
Most pyrolysis stoves regulate both fuel and air supply as opposed to controlling the combustion of fuel mass with simple air settings as in traditional furnaces.
Pellet fuel is usually fed into the pyrolysis chamber with screw conveyors. This leads to better and more efficient fuel combustion.
This technology is not new; has been used for decades in coal-fired coal fired boilers intended to burn coal with high volatile content.
Security and pollution considerations
Security
Correct airflow and ventilation are also important for efficient and safe wood burning. Specific requirements will be stipulated by the stove manufacturer. The legal requirements for new installations in the UK can be found in the Approved Building Rule of Document J, Part 2, Table 1 "Air Supply for Solid Fuel Equipment".
The safe operation of a wood burning stove requires routine maintenance such as emptying ash (container) under wood grate. Regular cleaning of stove and chimney pipes is also needed to prevent fire chimney. Creosote and soot gradually accumulate in stoves and chimneys. This can damage the chimney and spread the fire to surrounding structures, especially the roof. When soot prevents airflow through a stove or smokestack, smoke can accumulate in the stove and inside the house.
The basic principle of controlling combustion by reducing air supply means very often there is a reduction zone/condition inside the stove. This means that carbon dioxide is often "reduced" to carbon monoxide, which is highly toxic and should not be allowed to go home. This can happen if the stove or chimney is not cleaned or there is no adequate ventilation. Carbon monoxide or alarm detectors should always be installed in accordance with the manufacturer's recommendation where the wood stove is used. Not all smoke detectors detect carbon monoxide.
Fuel accelerators such as coal, grease, oil, gasoline, kerosene, plastics, etc., should also not be added to firewood in the wood stove, as the resulting fire could easily overwhelm the wood compartment and stove pipe and fire home.
UK smoke control areas
Under the United Kingdom Clean Air Act, local authorities may declare all or part of the authority area to become smoke control area. It is a violation to remove smoke from the building chimney, from the furnace or from the fixed boiler if it is in the specified smoke control area. It is also a violation to obtain "unauthorized fuel" for use in the smoke control area unless used in a "free" tool ("released" from the controls generally applicable in the smoke control area). The maximum rate of current penalty is Ã, Â £ 1,000 for each violation.
To comply with the Clean Air Act in the "smoke control area", exempt appliances or fuels should be used.
US pollution control requirements
The US Clean Air Act requires that the wood stove be certified by the Environmental Protection Agency (EPA). This device meets certain emission standards of no more than 7.5 grams per hour for non-catalytic wood stoves and 4.1 grams per hour for catalytic wood stoves. The state of Washington has more stringent requirements than a maximum of 4.5 grams per hour. However, the EPA has no mandatory emission limits for pellet stoves, indoor or outdoor wood boilers, stone stoves and certain types of wood stoves that are exempt from EPA regulations. The EPA is developing new regulations and by 2015, it will come into force, setting a mandatory emission limit for almost all wood burning equipment (fireplaces, chimeneas, and some other special equipment will still be excluded).
Justin Justa's stove, rocket stove and straw stove
In some places, such as the Caribbean, Central America and South America, many homes have wood burning stoves used indoors without good ventilation. Smoke lives in the home, where it is inhaled by the inhabitants, damaging their health. Nearly 2 million people die every year from indoor air pollution caused by open fire cooking, mostly women and children, according to the World Health Organization (WHO). Cutting firewood in large quantities also endangers forests and local ecosystems.
Non-governmental organizations (NGOs) such as Rotary International are actively assisting homeowners in building more fuel-efficient and safe wood burning stoves. One design is called Justa's stove, Just a stove, Ecostove, or La Estufa Justa. Justa's stove is made of materials such as adobe, cement, and pumice stone, with a chimney. Other types of wood burning stoves are also introduced to these communities, such as rocket stoves and haystoves. Rocket stoves up to 30% more fuel-efficient than Justa's stove, but a small portable rocket stove (for cooking) does not have a chimney and is only suitable for outdoor use. Larger rocket stoves are connected to chimney or exhaust pipe. The haybox stove is another outdoor firewood stove. Haybox stoves use straw, wool, or foam as an insulator, reducing fuel use by up to 70%.
Use in Europe
Italy is one of the biggest markets of pellet stoves in Europe, has about 30% of all homes that use wood for some heat. This means about 5 million homes have wood burning stoves or stoves.
Type
- Franklin's stove, originally created by Benjamin Franklin, is a more efficient type of wood burning fireplace. It's fussy and never caught, but many stoves continue to be called the "Franklin" stove.
- Carl Johan Cronstedt reportedly increased the efficiency of wood burning by a factor of eight in the mid-18th century.
- Fireplace insertion converts a wood burning fireplace into a wood burning stove. The fireplace inserts are self-contained units located within existing fireplaces and chimneys. They produce less smoke and require less wood than traditional fireplaces. Fireplace inserts are available in various sizes for large or small homes.
- Down draft or cross-draft gasification stoves, namely Dunsley Yorkshire, Welkom 600, Avalon Arbor (TM) wood stove, XEOOS.
- Stoves boilers provide hot water and heating. Backboiler can be an optional insert added to the rear of a fire box, or wrap it around a water jacket that is an integral part of the stove structure. The choice determines how much furnace output is used for heating space compared to the heating water.
- Rocket rock heaters are a type of fuel-efficient stoves, mentioned in the 70s, but dating back thousands of years. The super-hot chimney above the fire pulls the fire sideways and upwards, blending fuel and hot air into a rapid, hot, clean-burning fire that takes a bit of wood, leaves little residue, and has many uses.
See also
Note
References
Source of the article : Wikipedia
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