Condensation heat exchanger

A condensation heat exchanger comprising:

• at least one tube, helically wound so as to form a helical winding with adjacent turns and inside which a fluid to be heated circulates, the tube being made of a thermally good conductive material and having a planar or substantially planar front face and a planar or substantially planar rear face opposite to each other and perpendicular or approximately perpendicular to an axis of the helical winding, the helical winding being arranged so as to provide an interstice between the adjacent turns, each turn of the helical winding having an intrados end,
• a gas-tight casing inside which the at least one tube is mounted, the casing comprising a bottom and a facade on which a door is mounted, the casing being provided with a sleeve for discharging burnt gases,
• the front face of the tube being turned towards the facade of the casing and the rear face of the tube being turned towards the bottom of the casing,
• means for supplying and/or producing a hot gas inside the casing, mounted on the door,
• a discoid deflector being disposed inside the helical winding of the tube, so as to provide inside the casing, a combustion chamber between the door and the discoid deflector, and a condensation chamber between the discoid deflector and the bottom of the casing,
• the deflector comprising a disk made of thermally insulating material, carried by a sheet metal frame provided with a peripheral flange,
• the peripheral flange being interposed in an interstice between two successive turns of the helical winding,
• the peripheral flange having a front face turned towards the facade of the casing and a rear face turned towards the bottom of the casing, opposite to each other, and
• an external diameter of the discoid deflector being smaller than an internal diameter of the helical winding taken at the intrados ends of the turns, so as to provide, between an edge of the discoid deflector and the intrados end of a first turn of the helical winding located in the condensation chamber, a hot gas circulation passage,
• wherein the front face of the peripheral flange being positioned in a gas-tight manner against the rear face of a last turn of the helical winding located in the combustion chamber, to entirely block a radial gas passage outwardly from the combustion chamber between the front face of the peripheral flange and the rear face of the last turn of the helical winding,
• wherein at least one spacer element is disposed between the rear face of the peripheral flange and the front face of the first turn of the helical winding located in the condensation chamber, so as to provide therebetween a gas circulation interstice, so that the hot gases radially or approximately radially pass through the gas circulation interstice, from outside to inside of the helical winding, then axially pass through the hot gas circulation passage from front to back of the condensation heat exchanger, in the direction of the condensation chamber.