Every system that controls temperature has three main components: a source of hot or cold air, a way to distribute the air, and a device used to control climate settings. The control device is often a thermostat.
The different sources for cool and warm air, such as the air conditioner or furnace, usually use the same delivery method and control systems. Heating works on the principle that heat always moves from a warmer object to a cooler one. The function of heaters and furnaces is to pump air into the home in order to make it more warm.
All heating systems burn fuel. Most commonly, home heating systems burn gas or oil fuel, but some use electricity. An electrically powered heat pump heats and cools the air. In summer, in extracts hot air from the house, while in winter it pulls warm air from outside and distributes it to the interior of the home.
An active furnace consumes the fuel that powers it. The fuel being burned builds heat, which is then channeled into the home through ducts, wires or pipes. These pipes are connected to registers, radiators or heating panels where the air is blown out and into the house.