Mr. Heater F260550 Big Maxx MHU50NG Natural Gas Unit Heater Easy outside access to thermostat and A/C terminals and gas connection Limited 3 year warranty on parts and burners;Minimum 8 ft clearance from floor to base of heater required . Powered exhaust allows for vertical or horizontal venting Natural Gas to Liquid Propane conversion kit included 50,000 BTU per hour heats up to 1250 sq. ft.