Space heating

An electric space heater

This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (June 2008)

Space heating is the heating of a space, usually enclosed, such as a house or room.^[1] A space heater keeps the air and surroundings at a comfortable temperature for people or animals, or even plants in a greenhouse^[2]. Space heating generally warms a small space, and is usually held in contrast with central heating, which warms many connected spaces at once. Space heating does not include water heating, unless it is used for hydronic heating.

Heater types

While central boilers that heat buildings and houses heat space, the term space heater is normally used to refer to relatively small heaters, especially those that are portable or wall-mounted. These space heaters may use natural gas or propane, but they are most commonly electric. Electric heaters are safer because there is no danger of carbon monoxide poisoning. They are also cheaper to buy. However, they are often far more expensive to operate, because electricity is typically more expensive per unit of heat energy produced than gas or propane.^[3] However, a ground source heat pump operating with a coefficient of performance of more than 3 will be cheaper to operate than a gas heater.

Modern electric space heaters usually have ceramic heating elements rather than nichrome wires, and are fan-forced with a blower or squirrel-cage fan. These distribute heat much more evenly, and allow them to be encased in plastic, nearly eliminating the chance of burns or fire. Window and wall units, often seen in hotel rooms, are permanent space heaters. These often employ heat pumps, which use reverse-cycle air conditioning to transfer heat to the inside from the outside. The domestic incandescent bulb contributes a small but significant amount of heat to domestic interiors. It is more important in extremely well insulated homes, where such bulbs may be left on so as to extend their life.

Propane space heaters are generally one of two types, radiant (infrared) or circulation-type space heaters. Infrared propane space heaters function to heat objects which in turn heats the surrounding air whereas circulation type space heaters heat the air directly using a fan or convection. Additionally, propane space heaters are either vented or unvented. Unvented space heaters are low capacity heaters used to heat living areas but are not allowed in bedrooms, bathrooms or confined spaces due to fire danger and the possible accumulation of flue gases at high levels.

Kerosene heaters were once common. According to the National Fire Protection Association (NFPA), most of the 2,400 injuries involved children who drank the kerosene or inhaled the fumes. Another hazard is the reduction in air quality. One form is the lowering of the amount of oxygen in the air. Gases from kerosene, fuel oil or natural gas, if not properly vented, can cause headaches and irritate chronic respiratory ailments. Carbon monoxide is more readily attached to the hemoglobin of the blood than oxygen. Hence, carbon monoxide reduces the blood's ability to transport life-giving oxygen to the body's cells. A person who inhales carbon monoxide will not likely recover immediately when moved to good air. It may still be a long time (frequently 24 to 48 hours) before the carbon monoxide is completely removed from the blood.^[4]

District heating

In some countries district heating is a major source of space heating. This is especially the case in Scandinavia. District heating systems make it possible to distribute all of the energy for space heating as well as water heating from waste heat from industries, power plants, incinerators, geothermal heating and central solar heating.^[5]

Efficiency

In most areas, fossil fuels are burned to create heat, which is used to boil water and create steam to turn a turbine that turns a generator that produces electricity. The efficiency for the process ranges from about 20 to 60%. Another 5 to 15% is lost in transmission, depending how far the power plant is from the user. Gas heaters on the other hand, use the heat from combustion to directly heat the space through convection, which is much more efficient than electric heating.^[6]

In combined heat and power (CHP) plants the energy lost in e.g. turbine driven power plants is utilized for district heating. When space heating is supplied by district heating from CHP plants, the total energy efficiency approaches 100% (and may even exceed 100% based on the lower heating value of the fuel).^[7] CHP is a major part of the strategy for energy conservation and global warming prevention in Scandinavia - and increasingly in the rest of Europe.

References

See also

• Central heating
• District heating
• Electric heating
• Heater (types of heaters)
• Solar combisystem