Get tough jobs done even on chilly days when you warm up with the Mr. Heater Forced Air Propane 400,000 BTU Heater. Ideal for heating outdoor job sites, this heater supplies up to 400,000 BTUs per hour and can heat up to 10,000-square foot spaces. The QBT technology helps ensure quiet operation and the high temperature limit switch encourages safe and efficient use. The economical design allows for efficient and clean burning, while the steel construction offers rugged durability.