Electric Heater
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Electric heating is a process in which
electrical energy Electrical energy is the energy transferred as electric charges move between points with different electric potential, that is, as they move across a voltage, potential difference. As electric potential is lost or gained, work is done changing the ...
is converted directly to heat energy. Common applications include space heating,
cooking Cooking, also known as cookery or professionally as the culinary arts, is the art, science and craft of using heat to make food more palatable, digestible, nutritious, or Food safety, safe. Cooking techniques and ingredients vary widely, from ...
,
water heating Water heating is a heat transfer process that uses an energy source to heat water above its initial temperature. Typical domestic uses of hot water include cooking, cleaning, bathing, and space heating. In industry, hot water and water heated t ...
and industrial processes. An electric heater is an
electrical Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...
device that converts an electric current into heat. The
heating element A heating element is a device used for conversion of electric energy into heat, consisting of a heating resistor and accessories. Heat is generated by the passage of electric current through a resistor through a process known as Joule heating. He ...
inside every electric heater is an electrical
resistor A resistor is a passive two-terminal electronic component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active e ...
, and works on the principle of
Joule heating Joule heating (also known as resistive heating, resistance heating, or Ohmic heating) is the process by which the passage of an electric current through a conductor (material), conductor produces heat. Joule's first law (also just Joule's law), ...
: an
electric current An electric current is a flow of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is defined as the net rate of flow of electric charge through a surface. The moving particles are called charge c ...
passing through a resistor will convert that electrical energy into heat energy. Most modern electric heating devices use
nichrome Nichrome (also known as NiCr, nickel-chromium or chromium-nickel) is a family of alloys of nickel and chromium (and occasionally iron) commonly used as resistance wire, heating elements in devices like toasters, electrical kettles and space he ...
wire as the active element; the heating element, depicted on the right, uses nichrome wire supported by ceramic insulators. Alternatively, a
heat pump A heat pump is a device that uses electricity to transfer heat from a colder place to a warmer place. Specifically, the heat pump transfers thermal energy using a heat pump and refrigeration cycle, cooling the cool space and warming the warm s ...
can achieve around 150% – 600% efficiency for heating, or COP 1.5 - 6.0
Coefficient of performance The coefficient of performance or COP (sometimes CP or CoP) of a heat pump, refrigerator or air conditioning system is a ratio of useful heating or cooling provided to work (energy) required. Higher COPs equate to higher efficiency, lower energy ( ...
, because it uses electric power only for transferring existing thermal energy. The heat pump uses an
electric motor An electric motor is a machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a electromagnetic coil, wire winding to gene ...
to drive a reversed refrigeration cycle, that draws heat energy from an external source such as the ground or outside air (or the interior of a refrigerator) and directs that heat into the space to be warmed (in case of a fridge, the kitchen). This makes much better use of electric energy than direct electric heating, but requires much more expensive equipment, plus plumbing. Some heating systems can be operated in reverse for
air conditioning Air conditioning, often abbreviated as A/C (US) or air con (UK), is the process of removing heat from an enclosed space to achieve a more comfortable interior temperature, and in some cases, also controlling the humidity of internal air. Air c ...
so that the interior space is cooled and even hotter air or water is discharged outside or into the ground.


Space heating

Space heating is used to warm the interiors of buildings. Space heaters are useful in places where air-handling is difficult, such as in laboratories. Several methods of electric space heating are used.


Infrared radiant heaters

Electric infrared radiant heating uses heating elements that reach a high temperature. The element is usually packaged inside a
glass Glass is an amorphous (non-crystalline solid, non-crystalline) solid. Because it is often transparency and translucency, transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window pane ...
envelope resembling a light bulb and with a reflector to direct the energy output away from the body of the heater. The element emits
infrared radiation Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...
that travels through air or space until it hits an absorbing surface, where it is partially converted to heat and partially reflected. This heat directly warms people and objects in the room, rather than warming the air. This style of heater is particularly useful in areas through which unheated air flows. They are also ideal for basements and garages where spot heating is desired. More generally, they are an excellent choice for task-specific heating. Radiant heaters operate silently and present the greatest potential danger of ignition of nearby furnishings due to the focused intensity of their output and lack of overheat protection. In the United Kingdom, these appliances are sometimes called electric fires, because they were originally used to replace open fires. The active medium of the heater depicted in this section is a coil of nichrome resistance wire inside a fused silica tube, open to the atmosphere at the ends, although models exist where the fused silica is sealed at the ends and the resistance alloy is not nichrome.


Convection heaters


Natural convection

In a convection heater, the heating element heats the air in contact with it by
thermal conduction Thermal conduction is the diffusion of thermal energy (heat) within one material or between materials in contact. The higher temperature object has molecules with more kinetic energy; collisions between molecules distributes this kinetic energy ...
. Hot air is less
dense Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be use ...
than cool air, so it rises due to
buoyancy Buoyancy (), or upthrust, is the force exerted by a fluid opposing the weight of a partially or fully immersed object (which may be also be a parcel of fluid). In a column of fluid, pressure increases with depth as a result of the weight of t ...
, allowing more cool air to flow in to take its place. This sets up a
convection Convection is single or Multiphase flow, multiphase fluid flow that occurs Spontaneous process, spontaneously through the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoy ...
current of hot air that rises from the heater, heats up the surrounding space, cools and then repeats the cycle. These heaters are sometimes filled with oil or thermal fluid. They are ideally suited for heating a closed space. They operate silently and have a lower risk of ignition hazard if they make unintended contact with furnishings compared to radiant electric heaters.


Forced convection

A fan heater, also called a forced convection heater, is a kind of convection heater that includes an
electric fan A fan is a powered machine that creates airflow. A fan consists of rotating vanes or blades, generally made of wood, plastic, or metal, which act on the air. The rotating assembly of blades and hub is known as an '' impeller'', '' rotor'', or '' ...
to speed up the airflow. They operate with considerable noise caused by the fan. They have a moderate risk of ignition hazard if they make unintended contact with furnishings. Their advantage is that they are more compact than heaters that use natural convection and are also cost-efficient for portable and small room heating systems.


Storage heating

A storage heating system takes advantage of cheaper electricity prices, sold during low demand periods such as overnight. In the United Kingdom, this is branded as Economy 7. The storage heater stores heat in clay bricks, then releases it during the day when required. Newer storage heaters are able to be used with various tariffs. Whilst they can still be used with economy 7, they can be used with day-time tariffs. This is due to the modern design features that are added during manufacturing. Alongside new designs the use of a thermostat or sensor has improved the efficiency of the storage heater. A thermostat or sensor is able to read the temperature of the room, and change the output of the heater accordingly. Water can also be used as a heat-storage medium.


Domestic electrical underfloor heating

An electric
underfloor heating Underfloor heating and cooling is a form of Heating, ventilation, and air conditioning, central heating and cooling that achieves indoor climate control for thermal comfort using hydronics, hydronic or electrical heating elements embedded in a fl ...
system has heating cables embedded in the floor. Current flows through a
conductive In physics and electrical engineering, a conductor is an object or type of material that allows the flow of Electric charge, charge (electric current) in one or more directions. Materials made of metal are common electrical conductors. The flow ...
heating material, supplied either directly from the line voltage (120 or 240 volts) or at low voltage from a transformer. The heated cables warm the flooring by direct conduction and will switch off once it reaches the temperature set by the floor
thermostat A thermostat is a regulating device component which senses the temperature of a physical system and performs actions so that the system's temperature is maintained near a desired setpoint. Thermostats are used in any device or system tha ...
. A warmer floor surface radiates heat to colder surrounding surfaces (ceiling, walls, furniture.) which absorb heat and reflects all non absorbed heat to yet other still cooler surfaces. The cycle of radiation, absorption and reflection starts slowly and slows down slowly nearing set point temperatures and ceases to take place once equilibrium is reached all-round. A floor thermostat or a room thermostat or combination controls the floor on/off. In the process of radiant heating a thin layer of air which is in touch with the warmed surfaces also absorbs some heat and this creates a little convection (air circulation). Contrary to belief people are not heated by this warmed circulating air or convection (convection has a cooling effect) but are heated by the direct radiation of the source and reflection of its surrounds. Comfort is reached at lower air temperature due to eliminating circulating air. Radiant heating experiences highest comfort levels as people's own energy (± 70 Watt for an adult) (must radiate out in heating season) is in balance with its surrounds. Compared to convection heating system based on academic research the air temperatures may be lowered by up to 3 degrees. One variation is using tubes filled with circulating hot water as heat source for warming the floor. The heating principle remains the same. Both old style electric and warm water (hydronic) underfloor heating systems embedded in the floor construction are slow and cannot respond to external weather changes or internal demand/lifestyle requirements. The latest variant places specialized electric heating systems and blankets directly under the floor-decor and on top of additional insulation all placed on top of construction floors. Construction floors stay cold. The principle change of heat source positioning allows it to respond within minutes to changing weather and internal demand requirements such as life style being in/out, at work, rest, sleep, more people present/cooking, etc.


Lighting system

In large office towers, the lighting system is integrated along with the heating and ventilation system.
Waste heat Waste heat is heat that is produced by a machine, or other process that uses energy, as a byproduct of doing work. All such processes give off some waste heat as a fundamental result of the laws of thermodynamics. Waste heat has lower utility ...
from
fluorescent lamp A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, to produce ultraviolet and make a phosphor ...
s is captured in the return air of the heating system; in large buildings a substantial part of the annual heating energy is supplied by the lighting system. However, this waste heat becomes a liability when using air conditioning. Such expenses can be avoided by integrating an energy efficient lighting system that also creates an electric heat source.


Heat pumps

A heat pump uses an electrically driven compressor to operate a refrigeration cycle that extracts heat energy from outdoor air, the ground or ground water, and moves that heat to the space to be warmed. A liquid contained within the evaporator section of the heat pump boils at low pressure, absorbing heat energy from the outdoor air or the ground. The vapor is then compressed by a compressor and piped into a condenser coil within the building to be heated. The heat from the hot dense gas is absorbed by the air in the building (and sometimes also used for domestic hot water) causing the hot working fluid to condense back into a liquid. From there the high pressure fluid is passed back to the evaporator section where it expands through an orifice and into the evaporator section, completing the cycle. In the summer months, the cycle can be reversed to move heat out of the conditioned space and to the outside air. Heat pumps may obtain low-grade heat from the outdoor air in mild climates. In areas with average winter temperatures well below freezing, ground source heat pumps are more efficient than air source heat pumps because they can extract residual solar heat stored in the ground at warmer temperatures than is available from cold air. According to the US EPA,
geothermal heat pump A ground source heat pump (also geothermal heat pump) is a heating/cooling system for buildings that use a type of heat pump to transfer heat to or from the ground, taking advantage of the relative constancy of temperatures of the earth through ...
s can reduce energy consumption up to 44% compared with air source heat pumps and up to 72% compared with electric resistance heating. The high purchase price of a heat pump vs resistance heaters may be offset when
air conditioning Air conditioning, often abbreviated as A/C (US) or air con (UK), is the process of removing heat from an enclosed space to achieve a more comfortable interior temperature, and in some cases, also controlling the humidity of internal air. Air c ...
is also needed.


Liquid heating


Immersion heater

An immersion heater has an electrical resistance heating element encased in a tube, placed in the water (or other fluid) to be heated. The heating element might be inserted directly into the liquid, or installed inside a metal pipe to protect against corrosion and facilitate maintenance. Portable immersion heaters may not have a control thermostat, since they are intended to be used only briefly and under control of an operator. For domestic hot water supply, or industrial process hot water, permanently installed heating elements in an insulated hot water tank may be used, controlled by a
thermostat A thermostat is a regulating device component which senses the temperature of a physical system and performs actions so that the system's temperature is maintained near a desired setpoint. Thermostats are used in any device or system tha ...
to regulate temperature. Household units may be rated only a few kilowatts. Industrial water heaters may reach 2000 kilowatts. Where off-peak electric power rates are available, hot water may be stored to use when required. Minerals present in the water supply may precipitate out of solution and form a hard scale on the heating element surface, or may fall to the bottom of the tank and clog water flow. Maintenance of water heating equipment may require periodic removal of accumulated scale and sediment. Where water supplies are known to be highly mineralized, scale production can be reduced by using low-watt-density heating elements.


Electric shower


Electric water boiler


Circulation heaters

Circulation heaters or "direct electric heat exchangers" (DEHE) use heating elements inserted into a "shell side" medium directly to provide the heating effect. All of the heat generated by the electric circulation heater is transferred into the medium, thus an electric heater is 100 percent efficient. Direct electric heat exchangers or "circulation heaters" are used to heat liquids and gases in industrial processes.


Electrode heater

With an electrode heater, there is no wire-wound resistance and the liquid itself acts as the resistance. This has potential hazards, so the regulations governing electrode heaters are strict.


Environmental and efficiency aspects

The efficiency of any system depends on the definition of the boundaries of the system. For an electrical energy customer the efficiency of electric space heating is 100% because all purchased energy is converted to heat. However, if a
power plant A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the electricity generation, generation of electric power. Power stations are generally connected to an electr ...
supplying electricity is included, the overall efficiency drops drastically. For example, a fossil-fuel power station only delivers 3-5 units of electrical energy for every 10 units of fuel energy released. Even though the electric heater is 100% efficient, the amount of fuel needed to produce the heat is more than if the fuel were burned in a furnace or
boiler A boiler is a closed vessel in which fluid (generally water) is heated. The fluid does not necessarily boil. The heated or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating, centra ...
at the building being heated. If the same fuel could be used for space heating by a consumer, it would be more efficient overall to burn the fuel at the end user's building. On the other hand, replacing electric heating with fossil fuel burning heaters, isn't necessarily good as it removes the ability to have renewable electric heating, this can be achieved by sourcing the electricity from a renewable source. Variations between countries generating electrical power affect concerns about efficiency and the environment. In 2015 France generated only 6% of its electricity from
fossil fuels A fossil fuel is a flammable carbon compound- or hydrocarbon-containing material formed naturally in the Earth's crust from the buried remains of prehistoric organisms (animals, plants or microplanktons), a process that occurs within geologica ...
, while Australia sourced over 86% of its electricity from fossil fuels. The cleanliness and efficiency of electricity are dependent on the source. In
Sweden Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...
the use of direct electric heating has been restricted since the 1980s for this reason, and there are plans to phase it out entirely – see Oil phase-out in Sweden – while
Denmark Denmark is a Nordic countries, Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark,, . also known as the Danish Realm, a constitutionally unitary state that includes the Autonomous a ...
has banned the installation of direct electric space heating in new buildings for similar reasons.The Green Electricity Illusion
'' AECB'', published 2005-11-11, accessed 26 May 2007
In the case of new buildings, low-energy building techniques can be used which can virtually eliminate the need for heating, such as those built to the Passivhaus standard. In
Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...
, however, electric heating is still the most popular form of home heating. According to a 2003
Statistics Canada Statistics Canada (StatCan; ), formed in 1971, is the agency of the Government of Canada commissioned with producing statistics to help better understand Canada, its population, resources, economy, society, and culture. It is headquartered in ...
survey, 68% of households in the province use electricity for space heating. More than 90% of all power consumed in Quebec is generated by
hydroelectric dam Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...
s, which have low
greenhouse gases Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. Unlike other gases, greenhouse gases absorb the radiations that a planet emits, resulting in the greenhouse effect. T ...
emissions compared to fossil-fuel power stations. Low and stable rates are charged by
Hydro-Québec Hydro-Québec () is a Canadian Crown corporations of Canada#Quebec, Crown corporation public utility headquartered in Montreal, Quebec. It manages the electricity generation, generation, electric power transmission, transmission and electricity ...
, the provincially owned utility. In recent years there has been a major trend for countries to generate low-carbon electricity from renewable sources, adding to
nuclear power Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced by ...
and hydro-electric power which are long-standing low-carbon sources. For example, the
carbon footprint A carbon footprint (or greenhouse gas footprint) is a calculated value or index that makes it possible to compare the total amount of greenhouse gases that an activity, product, company or country Greenhouse gas emissions, adds to the atmospher ...
of UK electricity per kWh in 2019 was less than half that in 2010. However, because of high capital cost, the cost of electricity has not fallen and is typically 2-3 times that of burning fuel. Hence, direct electric heating may now give a similar carbon footprint to gas- or oil-fired heating, but the cost remains higher, though cheaper off-peak tariffs can reduce this effect. To provide heat more efficiently, an electrically driven
heat pump A heat pump is a device that uses electricity to transfer heat from a colder place to a warmer place. Specifically, the heat pump transfers thermal energy using a heat pump and refrigeration cycle, cooling the cool space and warming the warm s ...
can raise the indoor temperature by extracting energy from the ground, the outside air, or waste streams such as exhaust air. This can cut the electricity consumption to as little as 35% of that used by resistive heating. Where the primary source of electrical energy is hydroelectric, nuclear, or wind, transferring electricity via the grid can be convenient, since the resource may be too distant for direct heating applications (with the notable exception of
solar thermal energy Solar thermal energy (STE) is a form of energy and a technology for harnessing solar energy to generate thermal energy for use in Industrial sector, industry, and in the residential and commercial sectors. Solar thermal collectors are classified ...
). The electrification of heat of space and water heating is increasingly proposed as a way forward to decarbonise the current energy system, particularly with
heat pumps A heat pump is a device that uses electricity to transfer heat from a colder place to a warmer place. Specifically, the heat pump transfers thermal energy using a heat pump and refrigeration cycle, cooling the cool space and warming the warm s ...
. In case of large-scale electrification, impacts on the electricity grid due to potential increase in peak electricity demand and exposure to
extreme weather Extreme weather includes unexpected, unusual, severe weather, severe, or unseasonal weather; weather at the extremes of the historical distribution—the range that has been seen in the past. Extreme events are based on a location's recorded weat ...
events needs to be considered.


Economic aspects

The operation of electric resistance heaters to heat an area for long periods is costly in many regions. However, intermittent or partial day use can be more cost efficient than whole building heating due to superior zonal control. For example: A lunch room in an office setting has limited hours of operation. During low-use periods a "monitor" level of heat () is provided by the central heating system. Peak use times between the hours of 11:00 and 14:00 are heated to "comfort levels" (). Significant savings can be realized in overall energy consumption, since infrared radiation losses through
thermal radiation Thermal radiation is electromagnetic radiation emitted by the thermal motion of particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation. The emission of energy arises from a combination of electro ...
are not as large with a smaller temperature gradient both between this space and unheated outside air, as well as between the refrigerator and the (now cooler) lunch room. Economically, electric heat can be compared to other sources of home heating by multiplying the local cost per kilowatt hour for electricity by the number of kilowatts the heater uses. E.g.: 1500-watt heater at 12 cents per kilowatt hour 1.5×12=18 cents per hour. When comparing to burning fuel it may be useful to convert kilowatt hours to BTUs: 1.5 kWh × 3412.142=5118 BTU.


Industrial applications

Electric heating is widely used in industry. Donald G. Fink and H. Wayne Beaty, ''Standard Handbook for Electrical Engineers, Eleventh Edition'', McGraw-Hill, New York, 1978, , pages 21-144 to 21-188 Advantages of electric heating methods over other forms include precision control of temperature and distribution of heat energy, combustion not used to develop heat, and the ability to attain temperatures not readily achievable with chemical combustion. Electric heat can be accurately applied at the precise point needed in a process, at high concentration of power per unit area or volume. Electric heating devices can be built in any required size and can be located anywhere within a plant. Electric heating processes are generally clean, quiet, and do not emit much byproduct heat to the surroundings. Electrical heating equipment has a high speed of response, lending it to rapid-cycling mass-production equipment. The limitations and disadvantages of electric heating in industry include the higher cost of electrical energy compared to direct use of fuel, and the capital cost of both the electric heating apparatus itself and the infrastructure required to deliver large quantities of electrical energy to the point of use. This may be somewhat offset by in-plant (on-site) efficiency gains in using less energy overall to achieve the same result. Design of an industrial heating system starts with assessment of the temperature required, the amount of heat required, and the feasible modes of transferring heat energy. In addition to conduction, convection and radiation, electrical heating methods can use electric and magnetic fields to heat material. Methods of electric heating include resistance heating, electric arc heating, induction heating, and dielectric heating. In some processes (for example,
arc welding Arc welding is a welding process that is used to join metal to metal by using electricity to create enough heat to melt metal, and the melted metals, when cool, result in a joining of the metals. It is a type of welding that uses a welding power ...
), electric current is directly applied to the workpiece. In other processes, heat is produced within the workpiece by induction or dielectric losses. As well, heat can be produced then transferred to the work by conduction, convection or radiation. Industrial heating processes can be broadly categorized as low-temperature (to about ), medium-temperature (between ), and high-temperature (beyond ). Low-temperature processes include
baking Baking is a method of preparing food that uses dry heat, typically in an oven, but it can also be done in hot ashes, or on hot Baking stone, stones. Bread is the most commonly baked item, but many other types of food can also be baked. Heat is ...
and drying, curing finishes,
soldering Soldering (; ) is a process of joining two metal surfaces together using a filler metal called solder. The soldering process involves heating the surfaces to be joined and melting the solder, which is then allowed to cool and solidify, creatin ...
, molding and shaping plastics. Medium temperature processes include melting plastics and some non-metals for casting or reshaping, as well as annealing, stress-relieving and heat-treating metals. High-temperature processes include
steelmaking Steelmaking is the process of producing steel from iron ore and/or scrap. Steel has been made for millennia, and was commercialized on a massive scale in the 1850s and 1860s, using the Bessemer process, Bessemer and open hearth furnace, Siemens-M ...
, brazing,
welding Welding is a fabrication (metal), fabrication process that joins materials, usually metals or thermoplastics, primarily by using high temperature to melting, melt the parts together and allow them to cool, causing Fusion welding, fusion. Co ...
,
casting Casting is a manufacturing process in which a liquid material is usually poured into a mold, which contains a hollow cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a casting, which is ejected or ...
metals, cutting,
smelting Smelting is a process of applying heat and a chemical reducing agent to an ore to extract a desired base metal product. It is a form of extractive metallurgy that is used to obtain many metals such as iron-making, iron, copper extraction, copper ...
and the preparation of some chemicals.


See also

*
Auxiliary power unit An auxiliary power unit (APU) is a device on a vehicle that provides energy for functions other than propulsion. They are commonly found on large aircraft and naval ships as well as some large land vehicles. Aircraft APUs generally produce 115&n ...
*
Central heating A central heating system provides warmth to a number of spaces within a building from one main source of heat. A central heating system has a Furnace (central heating), furnace that converts fuel or electricity to heat through processes. The he ...
*
Diathermy Diathermy is electrically induced heat or the use of high-frequency electromagnetic currents as a form of physical therapy and in surgical procedures. The earliest observations on the reactions of the human organism to high-frequency electromagn ...
* Dielectric heating * Electroslag welding * Electroslag remelting *
Energy conservation Energy conservation is the effort to reduce wasteful energy consumption by using fewer energy services. This can be done by using energy more effectively (using less and better sources of energy for continuous service) or changing one's behavi ...
*
Head-end power In rail transport, head-end power (HEP), also known as electric train supply (ETS), is the electrical power distribution system on a passenger train. The power source, usually a locomotive (or a generator car) at the front or 'head' of a train, ...
*
Heater Heating, ventilation, and air conditioning (HVAC ) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. ...
(types of heaters) *
Heating, ventilation, and air conditioning Heating, ventilation, and air conditioning (HVAC ) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. H ...
* Hotel electric power *
Infrared heater An infrared heater or heat lamp is a heating appliance containing a high-temperature emitter that transfers energy to a cooler object through electromagnetic radiation. Depending on the temperature of the emitter, the wavelength of the peak of th ...
*
Microwave oven A microwave oven, or simply microwave, is an electric oven that heats and cooks food by exposing it to electromagnetic radiation in the microwave frequency range. This induces Dipole#Molecular dipoles, polar molecules in the food to rotate and ...
*
Renewable energy Renewable energy (also called green energy) is energy made from renewable resource, renewable natural resources that are replenished on a human lifetime, human timescale. The most widely used renewable energy types are solar energy, wind pow ...
*
Thermal efficiency In thermodynamics, the thermal efficiency (\eta_) is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, steam turbine, steam engine, boiler, furnace, refrigerator, ACs etc. For ...
* Thermal immersion circulator *
Underfloor heating Underfloor heating and cooling is a form of Heating, ventilation, and air conditioning, central heating and cooling that achieves indoor climate control for thermal comfort using hydronics, hydronic or electrical heating elements embedded in a fl ...


References

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