Feature: ['Operates as a natural gas furnace out of the box, and can be easily converted to a propane furnace with optional propane conversion kit (see Accessories tab). Corrosion-resistant, aluminized-steel tubular furnace heat exchanger Furnace is designed for multi-position installation - Goodman GMS8: upflow, horizontal right or left; Goodman GDS8: dedicated downflow Energy-saving, reliable hot surface ignition system with Goodman furnace patented adaptive learning algorithm to maximize igniter life Al', 'This listing consists of the Goodman 80% AFUE 100,000 BTU Gas Furnace ONLY', 'USA'] (Page 1)