Gas furnaces, like air conditioners, come in various sizes and efficiency levels to fit different home heating needs. These systems run on propane (LP) or natural gas, using burners to generate heat. Their efficiency is measured by AFUE (Annual Fuel Utilization Efficiency), which indicates how much of the fuel is converted into usable heat.

For example, an 80% AFUE furnace converts 80% of its fuel into heat, while the remaining 20% is lost through exhaust. Modern gas furnaces can range from 80% to 97% AFUE, with higher efficiency models providing greater energy savings.

When a gas furnace is paired with a heat pump, it creates a dual fuel system—one of the most efficient ways to heat a home. The system automatically switches between the heat pump and gas furnace based on outdoor temperatures, ensuring optimal comfort and energy efficiency year-round.