Condensing boiler

Abstract

A condensing boiler, which comprises an outer enclosure, which defines a chamber for containing water to be heated and accommodates a combustion chamber which is connected to a plurality of heat exchange tubes which lead into a fume collection chamber which is connected to a fume evacuation stack; a condensing device for the fumes is arranged in the fume collection chamber; the stack has an intake which is arranged substantially coaxially to the fume collection chamber and the condensing device comprises at least one fume cooling element which has a substantially annular shape and is arranged substantially coaxially to the fume collection chamber.

What is claimed is: 
     
         1 . A condensing boiler comprising an outer enclosure defining internally a chamber for containing water to be heated, which is provided with an inlet which can be connected to a duct for the return of cold water and with an outlet which can be connected to a duct for the delivery of hot water, and accommodating internally a combustion chamber, which is associated with a burner and is connected to a plurality of heat exchange tubes which pass through said containment chamber and lead, with an outlet end thereof, into a fume collection chamber, which is substantially cylindrical and is connected to a fume evacuation stack, inside said fume collection chamber there being a condensing device for the fumes that arrive in said fume collection chamber, wherein said stack has an intake which is arranged substantially coaxially to said fume collection chamber and in that said condensing device comprises at least one fume cooling element which has a substantially annular shape and is arranged substantially coaxially to said fume collection chamber in order to be skimmed radially on its outer surface by a flow of the fumes that arrive from said heat exchange tubes and are directed toward the intake of said stack. 
     
     
         2 . The boiler according to  claim 1 , wherein said at least one cooling element is provided internally with a flow cavity for a heat exchange fluid. 
     
     
         3 . The boiler according to  claim 1 , wherein said at least one cooling element has at least one intake port which is connected, by way of a bypass duct, to said cold water return duct, and at least one outlet port which is connected to said containment chamber. 
     
     
         4 . The boiler according to  claim 1 , wherein the outlet ends of said heat exchange tubes are distributed around an axis of said fume collection chamber along a circumference, said at least one cooling element having an outer perimetric edge which has a smaller diameter than said circumference. 
     
     
         5 . The boiler according to  claim 4 , wherein said condensing device has a plurality of cooling elements which are arranged so as to face each other and are substantially mutually coaxial, so as to define, between said cooling elements, a plurality of regions for channeling the fumes each one of which is intended to be crossed radially by a flow of the fumes that is directed from the outer perimetric edge of said cooling elements toward the axis of said fume collection chamber. 
     
     
         6 . The boiler according to  claim 5 , wherein said cooling elements define axially a channel for merging flows of the fumes that pass through said channeling regions. 
     
     
         7 . The boiler according to  claim 3 , wherein each one of said cooling elements is connected, with its intake port, to an intake manifold by way of a respective intake duct, and by way of its outlet port to an outlet manifold, by way of a respective discharge duct, said intake manifold being connected to said bypass duct and said outlet manifold by way of a connecting duct which leads into said containment chamber. 
     
     
         8 . The boiler according to  claim 4 , wherein said cooling elements have a narrowed portion proximate to their outer perimetric edge and an enlarged portion proximate to a corresponding inner perimetric edge. 
     
     
         9 . The boiler according to  claim 1 , wherein said fume collection chamber is arranged, with respect to said containment chamber, on an opposite side with respect to said burner. 
     
     
         10 . The boiler according to  claim 5 , further comprising circular gaskets which act between said cooling elements and walls arranged at axial ends of said fume collection chamber, in order to prevent the fumes from flowing directly toward the stack without passing through said channeling regions.