Available in 90% efficient and 95% efficient models. Thermo Pride gas furnaces last twice as long as furnaces with the traditional "clam-shell" design of a heat exchanger. You get more heat for twice the life at the same cost. Ask about Thermo Prides 'Peace of Mind" warranty, offering complete furnace replacement should the heat exchanger fail in the first ten years. Due to the efforts by the EPA and DOE to reduce emmissions and fuel waste, Thermo Pride has stopped producing the low efficiency 80% gas furnaces.