Patent ID: 8733337

Claim:
A heat exchanger for a high efficiency hot air heating appliance, comprising: at least one segment arranged to form a flow channel with an inlet and an outlet for hot combustion gases, said at least one segment comprising a primary section and a secondary condensing section coupled to the primary section following in the flow direction of the combustion gases, said segment further comprising at least one primary element having an input and an output configured to form part of the primary section of the segment and at least two secondary condensing elements coupled to the at least one primary element to form part of the secondary condensing section of the segment, each of said at least two secondary condensing element having an input and output, wherein said at least one primary element is integrally formed with one of the at least two secondary condensing elements being constructed from a double element, wherein said double element comprises a branch opening at a location of a transition between the output of the at least one primary element and the input of the one of the at least two secondary condensing elements, and to which the inputs of the other secondary condensing elements of the segment are connected in parallel in such a way that gas flow coming from the at least one primary element is divided between the at least two secondary condensing elements coupled to the at least one primary element, wherein flow channels for air to be heated are disposed between the at least two secondary condensing elements, and wherein the double element is formed as a two-walled whole from two preformed shells that are affixed together to form the flow channel so that said double element comprises the input for the at least one primary element, the output for the one of the at least two secondary condensing elements coupled to the at least one primary element, and the branch opening at the location of the transition between the at least one primary element and the one of the at least two secondary condensing elements.