![Model](https://upload.wikimedia.org/wikipedia/commons/c/ce/Model_%22S%22_Convection_Heater_-_1924.png)
A convection heater (otherwise known as a convector heater) is a type of heater that uses
convection
Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the convec ...
currents to heat and circulate air. These currents circulate throughout the body of the appliance and across its
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 independe ...
. This process, following the principle of
thermal conduction
Conduction is the process by which heat is transferred from the hotter end to the colder end of an object. The ability of the object to conduct heat is known as its ''thermal conductivity'', and is denoted .
Heat spontaneously flows along a tem ...
, heats up the air, reducing its density relative to colder air and causing it to rise.
As heated air molecules rise, they displace cooler air molecules down towards the heating appliance. The displaced cool air is heated as a result, decreases in density, rises, and repeats the cycle.
History
Ancient heating systems, including
hearths
A hearth () is the place in a home where a fire is or was traditionally kept for home heating and for cooking, usually constituted by at least a horizontal hearthstone and often enclosed to varying degrees by any combination of reredos (a low, ...
,
furnace
A furnace is a structure in which heat is produced with the help of combustion.
Furnace may also refer to:
Appliances Buildings
* Furnace (central heating): a furnace , or a heater or boiler , used to generate heat for buildings
* Boiler, used t ...
s, and
stove
A stove or range is a device that burns fuel or uses electricity to generate heat inside or on top of the apparatus, to be used for general warming or cooking. It has evolved highly over time, with cast-iron and induction versions being develope ...
s, operated primarily through convection. Fixed central hearths, which were first excavated and retrieved in Greece, date back to 2500BC, while crude fireplaces were used as early as the 800sAD and in the 13th century, when castles in Europe were built with fireplaces with a crude form of chimney.
Developments in convection heating technology included the publication of the very first manual on fireplace design called ''Mechanique du Feu'' in 1713, the creation of stoves with
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 ...
ic control in 1849, and the rise of numerous cast iron stove manufacturers during the
American Civil War
The American Civil War (April 12, 1861 – May 26, 1865; also known by other names) was a civil war in the United States. It was fought between the Union ("the North") and the Confederacy ("the South"), the latter formed by states th ...
.
The Model "S", illustrated by the Sala Heater & Mantel Co. in
Dallas, Texas
Dallas () is the third largest city in Texas and the largest city in the Dallas–Fort Worth metroplex, the fourth-largest metropolitan area in the United States at 7.5 million people. It is the largest city in and seat of Dallas County w ...
in 1924, is an example of an early model of a convection
space heater
A space heater is a device used to heat a single, small to medium sized area.
Operation
Electric space heaters fall into four main categories: fan heaters, ceramic, infrared, and oil-filled.
* Fan heaters are the cheapest, but are often the ...
. This model consisted of three stoves and was considered to be a highly efficient radiant type of gas heater at the time. It utilized
radiant heat
Thermal radiation is electromagnetic radiation generated by the thermal motion of particles in matter. Thermal radiation is generated when heat from the movement of charges in the material (electrons and protons in common forms of matter) is ...
, and supplemented its power by drawing cold air through the facing, heating it, and forcing it out through the register. This allowed air circulation while maintaining a cool exterior on the appliance.
These early developments, along with the technological advancements made possible by
electricity
Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described ...
and inventions of tools like
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 ...
s, gave way for the design of modern convection heaters.
Types
Convection heaters are commonly classified according to their power source. Electric convection heaters use electricity, while combustion or gas-fired heaters use gas,
propane
Propane () is a three-carbon alkane with the molecular formula . It is a gas at standard temperature and pressure, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used a ...
, or any other type of fuel. For the heating element, convection heaters usually use metal coils, nickel-chromium,
resistance wire
Resistance wire is wire intended for making electrical resistors (which are used to control the amount of current in a circuit). It is better if the alloy used has a high resistivity, since a shorter wire can then be used. In many situations, the ...
, thermal fluids, or ceramic.
Panel heater
A panel heater is a type of electric convection heater commonly used for heating rooms in residential and small commercial settings. They are often mistaken for
electric radiator
Electric heating is a process in which electrical energy is converted directly to heat energy at around 100% efficiency, using rather cheap devices. Common applications include space heating, cooking, water heating and industrial processes. ...
s, which are devices that use radiant heating and transfer heat directly to objects rather than using the air as medium. Panel heaters are typically used in complement to some other primary or
central heating system
A central heating system provides warmth to a number of spaces within a building from one main source of heat. It is a component of heating, ventilation, and air conditioning (short: HVAC) systems, which can both cool and warm interior spaces.
...
. They are usually fitted with time and temperature controls.
Fan heater
Fan heaters combine the warming capability of a heater and air distribution capacity of a fan. The earliest fan heaters became available in the 1950s, right after the invention of
tangential fan
A fan is a powered machine used to create a flow of air. A fan consists of a rotating arrangement of 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 ''imp ...
s.
Modern fan heaters have variable-speed fans that can work independently from the heating element.
Institutional convector heater
Institutional convector heaters are heavy-duty heaters designed strictly for commercial and industrial use.
Their construction is designed to reach a broad surface area.
Oil heater
An
oil heater
An oil heater, also known as an oil-filled heater, oil-filled radiator, or column heater, is a common form of convection heater used in domestic heating. Although filled with oil, it is electrically heated and does not involve burning any oil f ...
, also called a column heater, is electrically heated and uses oil as a heat reservoir. Because oil has a high
heat capacity
Heat capacity or thermal capacity is a physical property of matter, defined as the amount of heat to be supplied to an object to produce a unit change in its temperature. The SI unit of heat capacity is joule per kelvin (J/K).
Heat capacity i ...
and a high boiling point, it is a suitable heat pathway between the heating element and the cavities of the heater unit.
Gas-fired convection heater
Gas-fired convection heaters use a gas supply instead of electricity. These heaters consist of a gas burner, an air filter, gas valves, a blower, and a thermostat.
See also
*
Radiator
Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in cars, buildings, and electronics.
A radiator is always a ...
*
Electric heating
Electric heating is a process in which electrical energy is converted directly to heat energy at around 100% efficiency, using rather cheap devices. Common applications include space heating, cooking, water heating and industrial processes. An ...
References
{{HVAC , state=collapsed
Heaters
Convection