The central heating system provides warmth to all parts of the building (or part of the building) from one point to several rooms. When combined with other systems to control the building climate, the entire system may be an HVAC system (heating, ventilation and air conditioning).
Video Central heating
Overview
Central heating differs from space heating because the formation of heat occurs in one place, such as furnace chambers or basements in homes or mechanical spaces in large buildings (though not necessarily at the geometric "center" point). Heat is distributed throughout the building, usually by forced air through water channels, by water circulating through pipes, or by steam being inserted through pipes. The most common method of heat generation involves burning fossil fuels in a furnace or boiler.
In most temperate zones, most of the separate housing areas have central heating installed since before the Second World War. Where coal is available (ie Anthracite coal region in northeastern Pennsylvania) steam coal or a common hot water system. In more recent times, it has been updated to use fuel oil or gas as a source of combustion, eliminating the need for large coal deposits near the boiler and the need to remove and dispose of ash after coal is burned. The coal system is mostly now used for larger buildings.
A cheaper alternative to hot water or hot steam is forcing hot air. An oven burns fuel oil, which heats air in a heat exchanger, and the blower fan circulates the warmed air through the channel network to the rooms inside the building. This system is cheaper because the air moves through a series of non-piped channels, and does not require a pipe loader to be installed. The space between the floor blocks can be boxed and used as some air ducts, which further decreases the cost.
Electric heating systems are less common and practical only with low-cost electricity or when heat source heat pumps are used. Considering a combined system of thermal power generation and heating of electrical resistance, the overall efficiency would be less than the direct use of fossil fuels for heating the room.
More and more buildings utilize solar powered heat sources, in this case the distribution system usually uses water circulation.
Alternatives to such systems are gas heating and district heating. District heating uses waste heat from industrial processes or power plants to provide heat for neighboring buildings. Similar to cogeneration, this requires underground piping to circulate hot water or steam, and is only practical in relatively small areas (ie several city blocks).
Maps Central heating
History
Ancient Rome and Greece
The ancient Greeks initially developed central heating. The temple of Ephesus is heated by a chimney that is planted in the ground and circulates the heat generated by fire. Several buildings in the Roman Empire used a central heating system, conducting heated air with a furnace through empty space under the floor and out of the pipe (called caliducts ) on the wall - a system known as hypocaust .
Roman Hypocaust continued to be used on a smaller scale in the late Antiquity era and by the Umayyad caliphate, while Muslim builders used a simpler floor-to-pipe system.
After the collapse of the Roman Empire, throughout Europe, heating back to a more primitive fireplace for nearly a thousand years.
In the early medieval Alps, the simpler central heating system in which heat travels through the ducts beneath the floor of the furnace room replaces the Roman hypocaust in some places. In Reichenau Abbey, an interconnected underground channel network heats 300 m² large meeting rooms of monks during the winter months. The system efficiency level has been calculated at 90%.
In the 13th century, Cistercian monks revived central heating in Christian Europe using river diversion combined with an indoor wood burning stove. The well-preserved Monastery of Our Lady of the Wheel (founded in 1202) on the Ebro River in the Aragon region of Spain provides a very good example of such an application.
Modern central heating system
Three main methods of central heating were developed in the late 18th century until the mid-19th century.
Hot air
William Strutt designed a new mill in Derby with a central hot-air furnace in 1793, although the idea had been suggested by John Evelyn almost a hundred years earlier. The Strutt design consists of a large stove that heats air brought in from the outside by a large underground passage. The air is ventilated through the building by a large central channel.
In 1807, he collaborated with other renown engineer Charles Sylvester on the construction of a new building into Derby's Royal Infirmary home. Sylvester was instrumental in applying Strutt's novel heating system to a new hospital. He published his ideas in The Philosophy of Domestic Economy; as exemplified in the Heating, Ventilating, Washing, Drying & amp; Cooking,... in Derbyshire General Infirmary in 1819. Sylvester documented new ways of hospital warming included in the design, and healthier features such as toilets that cleaned and refreshed air. The infirmary novel heating system allows the patient to breathe fresh air fresh while the old air is supplied to a glass and iron dome at its center.
Their design proved to be very influential. They were widely copied in new factories in the Midlands and continuously improved, reaching maturity with de Chabannes's work on House of Commons ventilation in the 1810s. This system remains the standard for heating small buildings for the rest of the century.
Steam
The English writer, Hugh Plat, proposed a central steam-based heating system for greenhouses in 1594, though this was an isolated and unsupervised event until the 18th century. Colonel Coke designed a pipe system that would bring steam around the house from the central boiler, but James Watt was the Scottish inventor who was the first to build a working system at his home.
The central boiler supplies high-pressure steam which then distributes heat inside the building through a pipe system embedded in the column. He applied the system on a much larger scale at a textile factory in Manchester. Robertson Buchanan wrote a definitive description of this installation in his treatise published in 1807 and 1815. Thomas Tredgold's The Principles of Heating and Public Buildings Ventilation, , describes the method of applying heat steam heating to smaller, industrial buildings. This method has replaced the hot air system at the end of the 19th century.
Hot water
The early hot water system was used in Russia for central heating of the Summer Palace (1710-1714) Peter the Great in Saint Petersburg. A little later, in 1716, came the first use of water in Sweden to distribute the heating in the buildings. MÃÆ'  ¥ rten Triewald, a Swedish engineer, used this method for greenhouses in Newcastle upon Tyne. Jean Simon Bonnemain (1743-1830), a French architect, introduced this technique to an industry in a cooperative, in ChÃÆ' Â| teau du PÃÆ'ªcq, near Paris.
However, these scattered efforts were isolated and largely confined in their application to the greenhouse. Tredgold initially rejected its use as impractical, but changed its mind in 1836, when technology entered a rapid development phase.
Initial systems have used low-pressure water systems, which require very large pipes. One of the first modern central heating systems to fix this deficiency was installed by Angier March Perkins in London in the 1830s. At that time, central heating became popular in the UK, with a commonly used steam or hot air system.
Perkins' 1832 apparatus distributes water at 200 degrees Celsius (392 Ã, Â ° F) through small diameter pipes at high pressure. An important discovery to make the system feasible is a screw thread, which allows the connection between the pipes to withstand the same pressure on the pipe itself. He also separates the boiler from heat sources to reduce the risk of explosion. The first unit was installed at the home of Bank of England Governor John Horsley Palmer so he could grow wine in the cold climate of England.
The system is installed in factories and churches throughout the country, many of them remaining in conditions that can be used for more than 150 years. The system is also adapted for use by bakers in preheating their ovens and in paper making from wood pulp.
Franz San Galli, a Prussian-born Russian businessman living in St. Petersburg. Petersburg, discovered radiators between 1855 and 1857, which was a major step in the final formation of modern central heating. Victoria's cast iron radiators became widespread in the late 19th century when companies, such as the American Radiator Company, expanded the market for cheap radiators in the US and Europe.
Energy source
The energy source selected for the central heating system varies by region. Major energy sources are selected based on cost, convenience, efficiency, and reliability. The cost of heating energy is one of the main costs of operating a building in cold climates. Some central heating mills may switch fuels for economic and comfort reasons; for example, homeowners can install wood burning stoves with power reserves for unattended operation occasionally.
Solid fuels such as wood, peat or coal can be stockpiled at the point of use, but are uncomfortable to handle and difficult to control automatically. Wood fuel is still in use where supplies are plentiful and building occupants do not mind the work involved in transporting fuel, removing ash, and treating fire. The pellet fuel system can automatically start a fire, but still needs manual removal from the ashes. Coal was once an important housing heating fuel but today is rarely found.
Liquid fuels are oil products such as heating oil and kerosene. This is still widely applied where other heat sources are not available. Fuel oil can be automatically fired in a central heating system and does not need to remove ash and little maintenance of the combustion system. However, the variable price of oil on the world market leads to erratic and high prices compared to some other energy sources. Institutional heating systems (office or school buildings, for example) can use low-cost bunkers to run their heating plants, but high capital costs are compared to more manageable liquid fuels.
Natural gas is a heating fuel that is widespread in North America and Northern Europe. The gas burner is automatically controlled and does not need to remove ash and less maintenance. However, not all regions have access to natural gas distribution systems. Petroleum gas or liquid propane may be stored at the point of use and periodically recharged by a moving tank installed in the truck.
Some areas have low electrical power, making electric heaters practical. Electrical heating can be either a pure-type heating type or using a heat pump system to take advantage of low-level heat in the air or soil.
A district heating system uses centrally located boilers or water heaters and circulates thermal energy into individual customers with hot or steam water circulation. It has the advantage of a highly efficient energy converter center than can use the best pollution control available, and it is professionally operated. District heating systems may use impractical heat sources to be installed into individual homes, such as heavy oils, byproducts, or nuclear fission (hypothetically). Distribution networks are more expensive to build than for gas or electricity heating, and so are found only in densely populated or solid communities.
Not all central heating systems require purchased energy. Some buildings are served by local geothermal heat, using hot water or steam from local wells to provide building heat. Such areas are rare. The passive solar system does not require fuel to be purchased but needs to be carefully designed for the site.
Calculate the output of the required heater
The heater output is measured in kilowatts or BTUs per hour. For home placement, heating, and the level of output required for the house, it needs to be calculated. This calculation is achieved by recording various factors - that is, what is above and below the room you want to heat up, how many windows are there, the type of external wall in the property and other factors that will determine the level of heat output needed to heat the space in adequate. This calculation is called heat loss calculation and can be done with BTU Calculator. Depending on the results of this calculation, the heater can actually fit the house.
Water heating
Circulating hot water can be used for central heating. Sometimes this system is called a hydronic heating system.
Common components of central heating systems that use water circulation include:
- Supply of fuel, electricity or district heating supply lines
- Boiler (or heat exchanger for district heating) that heats water in the system
- Pump for running water
- Radiator through hot water to release heat to the room.
Circulating water system using closed loop; the same water is heated and then reheated. The sealed system provides a central form of heating in which the water used for heating circulates independently of the normal water supply of the building.
The expansion tank contains compressed gases, separated from the water system sealed by the diaphragm. This allows the normal pressure variation in the system. The safety valve allows the water to exit the system when the pressure becomes too high, and the valve can open to replenish water from the normal water supply if the pressure drops too low. Closed systems offer an alternative to open ventilation systems, where steam can get out of the system, and be replaced from building water supplies through central storage and storage systems.
Heating systems in the UK and in other parts of Europe generally combine the needs of indoor heating with domestic hot water heating. This system is rare in the United States. In this case, hot water in a closed system flows through a heat exchanger in a hot water tank or hot water cylinder where it heats water from ordinary plain water supply for use on tap water or equipment such as a washing machine. or dishwasher.
Hydronic radiation floor heating systems use boilers or district heaters to heat water and pumps to drain hot water in plastic pipes installed in concrete slabs. The pipes, embedded in the floor, carry hot water that warms to the surface of the floor, where it broadcasts the heat energy into the room above. Hydronic heating systems are also used with antifreeze solutions in melting ice and snow systems for sidewalks, parking lots and streets. They are more commonly used in commercial hot-floor projects and the entire house is radiant, whereas electric heat radiation systems are more commonly used in smaller "heating" applications.
Steam heating
The steam heating system takes advantage of the high latent heat that is released when the vapor condenses into liquid water. In steam heating systems, each room is equipped with a radiator connected to a low-pressure steam source (boiler). The steam that enters the radiator condenses and secretes its latent heat, back to the liquid water. The radiator in turn heats the room air, and gives some direct radiation heat. The condensate water returns to the boiler either by gravity or with the help of the pump. Some systems use only one pipe for combined vapor and condensate returns. Because the trapped air prevents proper circulation, such a system has a vent valve to allow air to be cleaned. In domestic and small commercial buildings, steam is produced at relatively low pressure, less than 15 psig (200 kPa).
Steam heating systems are rarely installed in new single-family housing construction due to the cost of plumbing. The pipe must be carefully tilted to prevent blockage of the trapped condensate. Compared to other heating methods, it is more difficult to control the output of the steam system. However, steam can be sent, for example, between buildings on campus to enable the use of efficient central boilers and low-cost fuels. High buildings utilize low-density steam to avoid the excessive pressure required to circulate hot water from a boiler installed in the basement. In industrial systems, steam processes used for power generation or other purposes can also be utilized for heating the room. Steam for heating systems can also be obtained from heat recovery boilers using heat wasted from industrial processes.
Electric heater
Electric heating or heating resistance turns electricity directly into heat. Electric heat is often more expensive than the heat generated by combustion equipment such as natural gas, propane, and oil. Electric heat resistance can be provided by heating pads, space heating, radiation heaters, furnaces, wall heaters, or thermal storage systems.
The electric heater is usually part of the fan coil that is part of the central air conditioner. They circulate heat by blowing air across the heating element supplied to the furnace through the air duct back. The blower in the electric furnace transfers air over one to five coils or resistance elements normally rated at five kilowatts. Heating elements activate one by one to avoid overloading the electrical system. Overheating is prevented by a security switch called a limit controller or limit switch. This limit controller can turn off the stove if the blower fails or if something is blocking the airflow. The hot air is then sent back through the house through the supply line.
In larger commercial applications, central heating is provided through an air handler that combines the same components as a furnace but on a larger scale.
Heat pump
In mild climate the air source heat pump can be used to condition the building air during hot weather, and to warm the building using heat extracted from outdoor air in cold weather. Air-fed calorie pumps are generally uneconomical for outdoor temperatures well below freezing. In colder climates, geothermal heat pumps can be used to extract heat from the soil. For the economy, the system is designed for the average low winter temperatures and uses additional heating for extreme low temperature conditions. The advantage of a heat pump is to reduce the energy purchased to build the heater; often geothermal resource systems also supply domestic hot water. Even in places where fossil fuels provide the most electricity, geothermal systems can offset greenhouse gas production because most of the heat is supplied from the surrounding environment, with only 15-30% as electricity consumption.
Environmental aspects
From an energy efficiency standpoint, considerable heat is lost or wasted if only one room requires heating, since central heating has a distribution loss and (in the case of air force systems) can heat up some uninhabited space unnecessarily. In such buildings that require isolated heating, one may want to consider non-central systems such as individual heating, fireplaces or other devices. Alternatively, architects can design new buildings that can almost eliminate the need for heating, such as those built for Passive House standards.
However, if a building does require full heating, central heating burning may offer a more eco-friendly solution than heating the electrical resistance. This applies when electricity comes from fossil-fueled power plants, with up to 60% of energy in fuel lost (except for district heating) and about 6% in transmission losses. In Sweden the proposal is to phase out direct electric heating for this reason (see oil phase-out in Sweden). Nuclear, wind, solar and hydroelectric sources reduce this factor.
In contrast, central heating systems can use heated water inside or near buildings using high efficiency condensing boilers, biofuels, or district heating. Wet underfloor heating has proved ideal. It offers a relatively easy conversion option in the future to use emerging technologies such as heat pumps and solar system combosystems, thereby also providing future inspection.
Typical efficiency for central heating (measured on purchasing customer energy) is: 65-97% for gas-induced heating; 80-89% for fuel oil, and 45-60% for coal heating.
See also
References
Source
- HÃÆ'¤germann, Dieter; Schneider, Helmuth (1997). PropylÃÆ'¤en Technikgeschichte. Landbau und Handwerk, 750 v. Chr. bus 1000 n. Chr (2nd ed.). Berlin. ISBN: 3-549-05632-X
Further reading
- Adams, Sean Patrick. Home Fires: How Americans Stay Warm in the 19th Century (Johns Hopkins University Press, 2014), 183 pp
External links
- BBC Wales History - Live before central heating
Source of the article : Wikipedia
0 Comments