What type of gas is commonly used in residential gas furnaces?

Natural gas is widely used in residential gas furnaces due to its availability, efficiency, and cost-effectiveness. It is sourced from underground gas fields and is delivered to homes through pipelines, making it a convenient choice for heating. Additionally, natural gas burns cleanly, producing a high amount of heat with lower emissions compared to other fuel options.

While propane is also a viable fuel option for gas furnaces, particularly in areas without natural gas access, it typically serves as a secondary choice. Nitrogen is not used as a fuel in furnaces; instead, it is an inert gas that does not contribute to combustion. Butane, though combustible and sometimes used in portable heaters, is less common in residential heating systems compared to natural gas. Thus, natural gas stands out as the primary fuel source for most residential gas furnaces.