“Parker felt that the fireplace was not enough to keep her and her home warm during the cold New Jersey winter, and designed the first gas furnace that was powered by natural gas and the first heating system to contain individually controlled air ducts that distributed heat evenly throughout the building. Parker's heating system used independently controlled burner units that drew in cold air and conveyed the heat through a heat exchanger. This air was then fed into individual ducts to control the amount of heat in different areas.[10][4] What made her invention unique, was that it was a form of "zone heating" where temperature can be moderated in different parts of a building.[11][12][13]” - Wikipedia