Abstract: A multi-chambered combuster apparatus for the controlled burning of all forms of light combustible organic material and the generation of steam or dry heat energy, resulting in essentially pollution free combustion as atmospheric emissions have zero opacity and low particulate discharge. A primary combustion chamber in which air and fuel are introduced in controlled ratio has interior walls acting as ignition surfaces which also direct combustants in a cyclonic flow path. Combustion gases then expand into a counterflow chamber where cooling and deceleration causes settling of pollutants. The gas stream next enters a purification chamber, passing through a hot filtering medium which entraps any remaining fine particulate matter.