On-site burning in space heaters

On-site burning in space heaters. On-site burning in space heaters. Generators may burn used oil in used oil-fired space heaters if all of the following conditions are met: (1) The heater burns only used oil that the owner or operator generates or used oil received from household do-it-yourselfers. (2) The heater is designed to have a maximum capacity of not more than 0.5 million Btu per hour. (3) The combustion gases from the heater are vented to the ambient air.