A gas furnace is a part of a heating system, the purpose of which is to convert gas to heat. Gas furnaces are most commonly used in residential systems in cold weather climates.
Gas furnaces are connected with home thermostats. When the temperature on the thermostat drops below a specific setting, the furnace's ignition is lit inside the combustion chamber, and a flame is created. The air in this chamber is then transferred to the heat exchanger where it is heated and driven through the air ducts to the various rooms of a home. Excess gases are vented outside the home.