- Efficiency of up to 97% AFUE offers more heat for less money. - Modulating design continuously adjusts heating level in small increments to match the degree of comfort you need precisely. - Compact 33-inch height fits the space in your place. - Less Can Be More With one of most compact cabinets in the industry (33-inches high) this unit requires less space outside and provides more heating capacity inside. - Good Housekeeping Seal This model is proud to have earned the Good Housekeeping Seal a nearly century old symbol of quality and trust. - 10-Year Limited Parts and Lifetime Heat Exchanger Warranties This product is covered by some of the best warranties in the business: 10 year limited parts and lifetime heat exchanger warranties.