A fan heater, also called a blow heater, is a heater that works by using a fan to pass air over a heat source (e.g. a

heating element A heating element converts electrical energy into heat through the process of Joule heating. Electric current through the element encounters resistance, resulting in heating of the element. Unlike the Peltier effect, this process is indepen ...

). This heats up the air, which then leaves the heater, warming up the surrounding room. They can heat an enclosed space such as a room faster than a heater without fan, but like any fan, creates audible

noise Noise is unwanted sound considered unpleasant, loud or disruptive to hearing. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrations through a medium, such as air or water. The difference aris ...

Cost and efficiency

Electric fan heaters can be less expensive to buy than other heaters due to simple construction. The fan carries heat away from the device, which can be made smaller without overheating. The relatively small amount of electricity used to operate the fan is converted to additional heat, so that efficiency is not a problem. Electric fan heaters are more expensive to run than fuel powered heaters due to the cost of electricity. This makes them best suited to occasional use rather than as regularly used heat sources. Residential electric fan heaters are limited in capacity by the voltage of the electrical system, in 110/120 V countries, 15 A is a typical maximum, this results in many models being 1.5 kW, in 220/230 V countries, 3 kW is a maximum, however 2 kW is used as it is adequate for most use cases. Industrial fan heaters can draw more power. Externally vented non-electrical (combustion powered) fan heaters lose some heat to the outdoors, and are thus less efficient. These are used where it is necessary not to release the fumes of

combustion Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combus ...

into the heated area.

Control

Most modern fan heaters have a power setting to determine power output. Some also have 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 (control system), setpoint. Thermostats are used i ...

which switches off heating when the desired ambient temperature is reached. They do not maintain perfect room temperature control, since * the thermostat is usually attached to the body of the heater, and senses temperature there. * the basic bimetal

s usually have significant

hysteresis Hysteresis is the dependence of the state of a system on its history. For example, a magnet may have more than one possible magnetic moment in a given magnetic field, depending on how the field changed in the past. Plots of a single component of ...

. * Remote sensors and thermostats with less hysteresis are available but are less common, as they are more expensive and the basic fan heater is satisfactory for most purposes.

Heat sources

While the fans in fan heaters are electrically powered, various heat sources may be used: * Electric heating elements are common, and used in portable plug-in electric heaters. Although they may supply several kilowatts of heat, such heaters are usually small as the electric element itself is small. Since heat is removed by the fan, the body of the heater does not need to be an effective

heat sink A heat sink (also commonly spelled heatsink) is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant, where it is dissipated away from the device, ...

. * Hot water tubing is used where the heat is provided by a hydronic heating system. * Gas,

kerosene Kerosene, paraffin, or lamp oil is a combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in aviation as well as households. Its name derives from el, κηρός (''keros'') meaning " wax", and was re ...

, and sometimes other

fuel A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy b ...

s such as used

engine oil Motor oil, engine oil, or engine lubricant is any one of various substances used for the lubrication of internal combustion engines. They typically consist of base oils enhanced with various additives, particularly antiwear additives, detergen ...

are burnt in high-power fan heaters.

Safety

Electric fan heaters are unsealed appliances with live electric parts inside, so they are not safe to use in wet environments because of the

risk In simple terms, risk is the possibility of something bad happening. Risk involves uncertainty about the effects/implications of an activity with respect to something that humans value (such as health, well-being, wealth, property or the environm ...

of electrical injury if moisture provides a conductive path to electrically-live parts. Electric fan heaters usually have a thermal fuse close to the heating element(s) to prevent overheating damage in the event of fan failure or air intakes becoming blocked, and a tip-over switch to shut the heater off when the fan outlet is not in the required orientation. Metal-cased heaters may perform better in the case of possible fire-causing faults than plastic-cased ones, since the case will stay intact and is not flammable, but the metal case presents a higher risk of electric shock if a heater malfunctions. Portable

-powered fan heaters release all the fumes of

into the room, creating a

of poisoning by

carbon monoxide Carbon monoxide ( chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simpl ...

and

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...

. Most installed fuel fan heaters in the

first world The concept of First World originated during the Cold War and comprised countries that were under the influence of the United States and the rest of NATO and opposed the Soviet Union and/or communism during the Cold War. Since the collapse of ...

use a

heat exchanger A heat exchanger is a system used to transfer heat between a source and a working fluid. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct conta ...

and external ventilation, avoiding that

by venting the

gases to the outdoors.

Internal parts

Residential model

Typical fan heater's internal parts The picture immediately to the right (the top on the mobile site) shows most of the component parts of a typical plug-in electric fan heater. * The

is the coiled wire frame located behind the fan blades. * The

is at the top left. * The heat (wattage) selector

switch In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type of ...

is at the top right. * The switch at the bottom is a normally open switch that serves as a "tipover switch" safety device: as long as the heater is standing upright, the switch is engaged and the circuit is closed. * The grip for the

power cord A power cord, line cord, or mains cable is an electrical cable that temporarily connects an appliance to the mains electricity supply via a wall socket or extension cord. The terms are generally used for cables using a power plug to connect ...

is at the bottom right. Overheat cutouts The next picture shows the two overheat cutouts. The bimetal cutout (left) operates if the device overheats because the intake is blocked or the fan fails, and resets automatically or manually depending on specification, once the heater cools after the operational fault is corrected. The thermal fuse (right) is a

failsafe In engineering, a fail-safe is a design feature or practice that in the event of a specific type of failure, inherently responds in a way that will cause minimal or no harm to other equipment, to the environment or to people. Unlike inherent saf ...

backup device that will blow and disconnect the

permanently should the bimetal cutout fail to operate (e.g. due to its contacts

welding Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as b ...

together) and in so doing prevent extreme overheating which could result in a fire.

Industrial model

Industrial fan heaters use high-output finned

s in front of a fan to provide a larger airflow and higher kilowatt rating than many smaller residential fan heaters. Industrial fan heaters can be used in warehouses, shipping containers, clean rooms, shops and other general purpose heating applications. They can also be used as dryers or dehumidifiers with modified attachments or mountings. Portable industrial fan heaters tend to range from around 1.5 kW up to about 45 kW with either

axial Axial may refer to: * one of the anatomical directions describing relationships in an animal body * In geometry: :* a geometric term of location :* an axis of rotation * In chemistry, referring to an axial bond * a type of modal frame, in music * ...

centrifugal Centrifugal (a key concept in rotating systems) may refer to: *Centrifugal casting (industrial), Centrifugal casting (silversmithing), and Spin casting (centrifugal rubber mold casting), forms of centrifigual casting *Centrifugal clutch *Centrifu ...

fans and various staged controls and over-temperature safety limit controls.

References

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