The answer to 'how does furnace work' is a furnace is the central component of a home's heating system. It burns fuel, such as natural gas, propane, or heating oil, to generate heat. The heated air is then distributed through ductwork to the various rooms in the home.
The main components of a furnace include the burner, heat exchanger, blower, and thermostat. The burner ignites the fuel, which heats the air that passes over the heat exchanger. The blower then circulates the heated air through the ductwork and into the living spaces. The thermostat monitors the temperature and signals the furnace to turn on and off to maintain the desired temperature.