Details: The Raypak millivolt natural gas heater provides ease of use with its simple controls, wind resistance, fuel efficiency, and built to last cabinet. The mechanical thermostat can be set precisely to your liking , just set it, and forget it. The millivolt ignition system does not require external power. It generates its own current internally, with a small thermocouple driven by the constant pilot light. Its wind resistant design protects the unit from snow, sleet, wind, and falling debris. Both the cabinet and the internals are non-corrosive and rust resistant and the copper finned tubes allow for maximum heat transfer. Every fuel efficient heater is tested right before it is boxed up to ensure you'll get a top quality, troublefree heater. Features PolyTuf Textured powder coating, polymer headers, all copper-fin-tube heat exchanger, stainless steel tube sheet, 2 inch CPVC water connections, burner tray and fire tile. 266,000 BTU unit is designed for residential use only and does not require an external power source.