58CVA Performance Efficiency 80% AFUE Warranty 5-year limited parts 20-year warranty on "SuperSTM Heat Exchanger Controls Controls Supported Infinity, Thermidistat, Thermostat Diagnostics Over 70 parameters via PDA or laptop Technology Capacity 66,000 - 154,000 BTUH Blower Motor Variable-speed Primary Heat Exchanger Aluminized Steel Secondary Heat Exchanger SerpentuffTM polypropylene-coated   Fuel Natural Gas; convertible to liquid propane (LP) Aesthetics Profile 2 Stage; 4-way Multipoise Construction Galvanized steel Paint Baked on urethane base coat and polyester top coat