The amount of heat in a quantity of matter at a specific temperature and pressure.
Heat engine
A device that produces mechanical energy directly from two heat reservoirs of different temperatures. A machine that converts thermal energy to mechanical energy, such as a steam engine or turbine.
Heat exchanger
Apparatus, which transfers heat from one fluid to another in cooling or heating systems. Air conditioners use both a condenser and an evaporator. Steam and hot water radiators are heat exchangers, which are used to produce heat.
Heat gain
The amount of heat gained, measured in BTU's, from a space to be conditioned, at the local summer outdoor design temperature and a specified indoor design condition. An increase in the amount of heat contained in a space, resulting from direct solar radiation, heat flow through walls, windows, and other building surfaces, and the heat given off by people, lights, equipment, and other sources.
Heat gun
Device, much like a hair dryer, which changes electricity to heat with a blower to aim that heat at a surface, to soften paint for removal or to accelerate drying.
Heat loss
The amount of heat lost, measured in BTU's from a space to be conditioned, at the local winter outdoor design temperature and a specified indoor design condition. A decrease in the amount of heat contained in a space, resulting from heat flow through walls, windows, roof and other building surfaces and from exfiltration of warm air.
Heat of fusion
Heat needed to melt a particular solid. For example, gold becomes liquid at about 2,000 degrees F and iron at 2,730 degrees F.
Heat of vaporization
Heat needed to turn a liquid into a gas.
Heat pipe
A device that transfers heat by the continuous evaporation and condensation of an internal fluid.
Heat pump
Apparatus that can heat but also cool by changing its cycle and using a refrigerant, a compressor and heat exchanger.
