Goodman GDS80603AN Gas Furnace, Single-Stage Burner/Multi-Speed Blower, Downflow 80% AFUE - 60,000 BTU Operates as a natural gas furnace out of the box, and can be easily converted to a propane furnace with optional propane conversion kit Corrosion-resistant, aluminized-steel furnace tubular heat exchanger Designed for dedicated downflow installations Energy-saving, reliable furnace hot surface ignition system with patented adaptive learning algorithm to maximize igniter life Aluminized furnace steel inshot burners Energy-saving PSC, multi-speed, direct drive furnace blower motor Heater has quiet