Features continuous electronic iginition and adjustable heat output from 50,000 to 85,000 Btu an hour for buildings from 9,000 to 16,000 cu. ft. High-output fan for better circulation of heated air. Automatic electronic ignition will not take place unless heater is plugged in. Propane flow stops if heater is accidentally unplugged. Can be operated for hours (at low setting) from a standard 20-lb. tank. Powder-coated finish. Patent #5,553,220 AGA and CGA Certified.