Patent ID: 6158396
Filing Date: 2000-12-12
Classification: F24H,F28D,F28F

Abstract:
In a water boiler having a burner and coiled heat exchanger tube contained within an enclosed shell, the burner producing products of combustion, the center of the coiled heat exchanger tube being plugged by a core extending therein with a top facing the burner, the burner being at one longitudinal inlet end of the shell and the core being at the other longitudinal outlet end of the shell, the coiled tube being spaced from the core and enclosed shell by a radial aggregate distance,the improvement of the shell being a sealed assembly, the enclosed shell being welded together, the core being metal, the core being irreplaceable within the sealed assembly shell, the top of the core having a constantly reducing diameter facing the burner, the coiled heat exchanger tube having heat exchanging elements,said heat exchanging elements extending off of the coiled tube, said heat exchanging elements filling the radial aggregate distance between core and the enclosed shell, said heat exchanging elements having a pitch, said pitch being small, and said small pitch of said heat exchanging elements producing longitudinal but not radial movement of the products of combustion between the core and enclosed shell as such products move between the inlet and outlet ends.