Electric heating

The element is usually packaged inside a glass envelope resembling a light bulb and with a reflector to direct the energy output away from the body of the heater.

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.

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.

This sets up a convection current of hot air that rises from the heater, heats up the surrounding space, cools and then repeats the cycle.

They operate silently and have a lower risk of ignition hazard if they make unintended contact with furnishings compared to radiant electric heaters.

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.

A storage heating system takes advantage of cheaper electricity prices, sold during low demand periods such as overnight.

The storage heater stores heat in clay bricks, then releases it during the day when required.

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.

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.

Such expenses can be avoided by integrating an energy efficient lighting system that also creates an electric heat source.

In the summer months, the cycle can be reversed to move heat out of the conditioned space and to the outside air.

[4] The high purchase price of a heat pump vs resistance heaters may be offset when air conditioning is also needed.

The heating element might be inserted directly into the liquid, or installed inside a metal pipe to protect against corrosion and facilitate maintenance.

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.

Invented in Brazil in the 1930s due to a lack of central gas distribution and used frequently since the 1940s, the electric shower is a home appliance often seen in South and Central American countries due to the higher costs of gas distribution, combined with households that in most cases do not support conventional water heaters.

Variations between countries generating electrical power affect concerns about efficiency and the environment.

In Sweden 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 has banned the installation of direct electric space heating in new buildings for similar reasons.

[16] 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).

[17] 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.

Significant savings can be realized in overall energy consumption, since infrared radiation losses through thermal radiation 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.

[18] When comparing to burning fuel it may be useful to convert kilowatt hours to BTUs: 1.5 kWh × 3412.142=5118 BTU.

Electric heat can be accurately applied at the precise point needed in a process, at high concentration of power per unit area or volume.

Low-temperature processes include baking and drying, curing finishes, soldering, 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, brazing, welding, casting metals, cutting, smelting and the preparation of some chemicals.