An apparatus consisting of an energy source, a method of converting that energy to heat, and a transport system to convey the energy and heat to the point of use. Most heating systems include some manual or automatic method of controlling the heat output and delivery.
There are many sources of energy for use in heating. The earliest source, and still most common in developing countries, comprises wood and wood products such as paper, wood chips, and sawdust; peat is used in some cultures. Solar use for heating and electrical generation has become widespread, although economics discourages more general use. The generation of electrical energy requires the use of fossil fuels, water power, geothermal energy, or nuclear energy. Fossil fuels are used directly in furnaces and boilers. See also Electric power systems; Energy sources; Heat pump; Solar energy.
The energy source is converted into heat by various means. Wood and fossil fuels are converted by burning, or the combustion process. Electrical energy can be converted directly into heat by resistance heaters. Solar energy requires collectors, with conversion to heat or electricity.
Many methods deliver heat to the point of use. Radiation systems take several forms. Cast-iron column radiators, using steam or hot water, have largely been superseded by convector radiators using steam, hot water, or electricity. Panel-type radiators are also used in ceilings or in floors. All require a piping or electrical distribution system. Forced-air warm-air heating, using electric motor-driven circulating fans, is common. See also Central heating and cooling; Comfort heating; District heating; Hot-water heating system; Panel heating and cooling; Radiant heating; Steam heating; Warm-air heating system.
