Abstract: An automatic stoker boiler has a heat transfer compartment above a combustion chamber which is divided by a horizontal partition inclined upwardly from the rear end of the boiler towards but terminating short of the front end thereof to provide a restricted port between the thus established upper and lower portions. An endless link belt establishes the lower portion of the combustion chamber and hot gas conduits extend from the upper portion through the heat transfer compartment to the exhaust and which is provided with a draft inducing fan and adjustable damper. Underfire air under the control of an adjustable damper is introduced into the lower portion of the combustion chamber upwardly through the belt and air jets are delivered into the combustion chamber through the front end both above and below the port. A standby fluid fuel burner is located in the rear end of the upper chamber portion.

Abstract: A boiler has a chamber to contain a charge of wood that rests on the bottom of the chamber with the major portion of the charge within a water jacketed upper portion of the chamber but free to settle as combustion progresses. Combustion is confined to the bottom portion of the chamber due to the cooling effect of the water jacket and to a turbulent cross draft in the combustion zone. A special venturi section in the flue coupled with a pressure blower both induces the flow of hot gases from the combustion zone through a second chamber and a heat exchanger and also provides a stream of air from the venturi section to create the cross draft. An oil burner may be used in conjunction with the second chamber as an alternate heat source. The boiler also has a special base construction and assembly features.