Thermal fluid boiler

Claim 1

A thermal fluid boiler comprising: a. a combustion chamber having a longitudinally extending horizontal lateral inner wall and a front and a back end; b. a longitudinally extending horizontal outer wall concentrically mounted over said inner wall in space relation to define therewith a flow chamber for the fluid to be heated; c. an elongated baffle plate in said flow chamber, said plate having one longitudinal edge secured to the outer surface of said inner wall to extend away from said outer surface and with the other longitudinal edge thereof terminating short of the inner surface of said outer wall, said plate winding around said inner wall from said back to said front end in spaced turns and in an uninterrupted helix; d. a longitudinally extending horizontal external casing concentrically mounted over said outer wall in spaced relation to define therewith a chamber for the flow of flue gases from said combustion chamber, and e. a plurality of spaced fins in said flue gas chamber, said fins being fixed to and projecting from the outer surface of said outer wall but terminating short of said external casing to slow down the flow of flue gases, f. said fins being disposed along parallel lines making an acute angle with the longitudinal axis of said outer wall, the fins being also disposed parallel, with respect to one another, at an acute angle to said parallel lines.