Dyna-Glo GBF30DTDG-2 30,000 BTU Blue Flame Vent Free Garage Heater Dual fuel technology allows the unit to be operated with Liquid Propane or Natural Gas Blue Flame Technology works by convecting heat to warm the air the same way as a central heating system Up to 30,000 BTU's/hr heats up to 1,000 sq. ft. Thermostat control knob automatically maintains your room's ideal heat level No electricity required allows for reliable back-up heating incase of an emergency situation Separately sold optional fan (WHF100) improves the amount of square footage the heat reaches in a quiet, yet powerful way! Innovative Wrong Fuel Shut-Off prevents any hazard associated with incorrect fuel hook-up from EVER occuring 1 Year Warranty