Bring the warmth you need to the indoors and outdoors when you use the Mr. Heater Forced Air QBT 170,000 BTU Propane Heater. Ideal for heating indoor and outdoor job sites, this heater boasts a 170,000 BTU output for heating spaces up to 4,250 square feet and features an automatic solid state ignition for easy powering on the go. The Quiet Burner Technology (QBT) reduces the operation noise, while the high temperature limit switch encourages safe use.