There are four main types of furnaces: natural gas, oil, electric, and propane. Electric furnaces can heat the air by exposing heated elements, while other types of furnaces typically require a heat exchanger or chamber that warms the surrounding air. Finally, the thermostat signals the furnace to shut off when the set temperature is reached.

There are four main types of furnaces: natural gas, oil, electric, and propane. while other types of furnaces typically require a heat exchanger or chamber that warms the surrounding air.