Space heater

Household appliance that heats a single room or other small area
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A space heater is a device used to heat a single, small to medium sized area. This type of heater can be contrasted with central heating, which distributes heat to multiple areas.

All space heaters transfer heat to their environment via some combination of the three fundamental modes of heat transfer: convection, radiation, and conduction. Typically heaters are designed with either convection or radiation as the sole dominant mode.

Convective space heaters utilize convection to transfer heat from the power source to a space. These heaters typically either rely on natural or forced convection. Natural convection is a phenomenon where temperature variations in an environment generate fluid flow. Forced convection heaters utilize a device like a fan to generate air flow and spread heat at a faster rate. Sometimes called "fan heaters," these are often cheap but lack in efficiency and versatility.

Radiant space heaters transfer heat to directly to bodies in front of them via thermal radiation. Thermal radiation is a process by which objects at a high temperature emit heat in the form of electromagnetic waves. These heaters are often designed such that the frequency of the emitted waves are in the infrared part of the electromagnetic spectrum. The materials used in radiant heaters can vary. Halogen heaters have tungsten filaments in sealed quartz envelopes, mounted in front of a metal reflector in a plastic case. They operate at a higher temperature than nichrome wire heaters but not as high as incandescent light bulbs, radiating primarily in the infrared spectrum. They convert up to 86 percent of their input power to radiant energy, losing the remainder to conductive and convective heat.

Oil heaters transfer heat by convection and radiation.

Improper use can increase the risk of fire and burns. Safe operation includes:

Plugging space heaters directly into a wall outlet and not an extension cord (except for heavy duty extension cords (14 gauge wire or larger) or relocatable power tap, as they can overheat and cause fires. Inspecting plugs and cords periodically for cracks or damage, and replacing them if needed. Keeping flammable materials, such as paper, plastics, curtains, furniture, and bedding, at least 3 feet (0.91 m) away from the heater. Turning off the heater when the last adult leaves the room or goes to sleep and keeping children and pets three feet away from the heater. Placing heaters on a flat, hard, nonflammable surface. Avoiding the use of heaters near flammable materials such as paint or gasoline. Installing smoke alarms and carbon monoxide detectors nearby. The risk of fire (and burns) is sometimes less with oil filled heaters than those with fans, but some fan assisted heaters have a lower risk of fire (and burns) than other oil filled heaters.

No one type of heater is safer than any other type. The risk of fire and burns can vary, depending on model and manufacturer. (for portable electric space heaters) and UL 1042 standards (for portable and fixed baseboard electric heaters) certify heater safety. Although the General Services Administration had Specification W H 193 for electric space heaters, it was replaced in 1995 by the UL standards. Additional information on portable heater safety may be found at the Department of Energy's Energy Efficiency website.

New York City law regulates the safety of space heaters. Space heaters for sale in the city must have a thermostat to control temperature, an automatic shut off feature if the heater tips over or overheats, and must be certified and labeled by a nationally approved organization or laboratory.

The U. S. Environmental Protection Agency has evaluated a number of space heaters, but none have received its Energy Star label.