A heating system that utilizes a furnace is called a forced-air system. This type of system uses a thermostat to tell the furnace to turn on and begin heating a property when the interior temperature drops below a pre-selected level. When this happens, a valve in the furnace opens, which releases natural gas into the burner and tells the blower to begin running. The gas is then ignited by the pilot light or electric igniter within the combustion chamber. This creates heat in the exchanger, which is then blown through the ductwork and released into the living space. This process also creates combustion gases that are funneled through a flue and vented to the outside.
