Fixed versions were originally used mainly for supplemental heat for passenger compartments of automobiles and aircraft, with the latter still in production.
A fan blows air into a combustion chamber, where a glow plug or similar ignition device lights the gasoline/air mixture.
Gasoline heaters require an intake source of fresh air, and exhaust combusted gasses.
Due to the toxicity of the latter - carbon monoxide in particular - it is crucial to prevent spent gasses from entering a vehicle's interior.
Production at the Chicago firm began a short time later,[2] with more than 3 million units installed in automobiles, aircraft, and military vehicles by 1948.