Condensing heat exchanger

Abstract

The present invention relates to a condensing heat exchanger (10) comprising: - at least one tube (7) in the form of a helical winding (70) having a planar front end (71) and a planar rear end (72) and being housed in a housing (2); - means (5) for generating hot gas within the housing; - a disc-shaped guide (8) having a peripheral flange (823) and being arranged in the helical winding (70) such that its flange is inserted into a gap between two consecutive turns; and a combustion chamber (25) and a condensing chamber (26) are disposed within the housing (2). Notably, the front end (8231) of the flange (823) is hermetically attached to the rear end (72) of the last turn (702) of the winding (70) located in the combustion chamber (25). The exchanger is characterized by at least one protruding element (8233) disposed between the rear end (8232) of the flange (823) and the front end (71) of the first turn (703) located in the condensation chamber to provide a gap (73') between them for gas circulation. Furthermore, the outer diameter of the disc-shaped guide (D1) is smaller than the inner diameter (D2) of the helical winding (70) to provide a passage (27) for hot gas circulation.

Description

Technical Field

[0001] This invention belongs to the field of condensing heat exchangers.

[0002] More specifically, the present invention relates to the structure of a flow guide disposed between the combustion chamber and the condensation chamber of the exchanger, and the manner in which the flow guide is fixed. Background Technology

[0003] Attached Figure 1 A cross-sectional view of an exemplary embodiment of a condensing heat exchanger according to the prior art is shown.

[0004] In this figure, it can be seen that the condensing heat exchanger 1 includes a shell 2, a spiral wound tube 3, a door 4, a device 5 for supplying or generating hot gas, and a flow guide 6.

[0005] The heat exchanger 1 extends along the longitudinal axis X-X'. Figure 1 In the image, the heat exchanger is shown in its normal operating position.

[0006] The housing 2 includes a tubular body 20 extending along an axis X-X', the rear end of which is closed by a bottom 21, and the front end of which includes a front face 22. Conventionally, in the remainder of the specification and claims, the term "front" refers to the face facing the front of the exchanger, i.e., the face facing 22, while the term "rear" refers to the face facing the rear of the exchanger, i.e., the face facing the bottom 21.

[0007] The housing 2 includes a sleeve 23 for venting combustion gases. Furthermore, the lower portion of the housing 2 is slightly inclined to allow condensate to be discharged by gravity via an outlet port 24, which is connected to a conduit 240 for discharging the condensate.

[0008] The front surface 22 has an edge 220 around its periphery, which is hermetically secured (preferably welded or pressed) to the front edge of the tubular body 20. The front surface 22 includes a central opening 221 that can be closed by the door 4.

[0009] Door 4 supports a burner 50 (e.g., a gas or oil burner) at its central portion, which constitutes an exemplary embodiment of the device 5 for generating hot gas. The burner 50 may be replaced by a device for supplying hot gas, which is generated outside the housing 2 and propelled inside the housing (e.g., using a fan).

[0010] The tube 3 is spirally wound around itself, thus forming a helical winding 30 extending along the longitudinal axis X-X'. It has two ends forming an inlet nozzle and an outlet nozzle, which are not visible in the figure.

[0011] The tube is made of a material with good thermal conductivity, particularly metal (preferably stainless steel). The tube is designed to receive fluids to be heated, such as water.

[0012] Tube 3 has an elliptical straight cross-section (not shown in the figure) or a rectangular straight cross-section, the two longitudinal sides of which are flat, and its major axis is perpendicular or approximately perpendicular to the axis X-X' of the helical winding. Therefore, tube 3 has a front face 31 and a rear face 32. These faces 31 and 32 are planar or substantially planar depending on the cross-section.

[0013] A calibration value gap 33 exists between two adjacent turns of the tube 3. This gap 33 can be obtained, for example, using a boss 34 formed on one of the two planes of the tube 3 (here, for example, the front 31). These bosses are attached to... Figure 2 It displays better in the middle.

[0014] The diffuser 6 is disposed inside the helical winding 30 of the tube 3, perpendicular to the axis X-X', so as to provide a combustion chamber 25 inside the housing 2 on one side, which extends between the door 4 and the diffuser 6 and contains the burner 50, and a condensation chamber 26 on the other side, which extends between the diffuser 6 and the bottom 21 of the housing 2.

[0015] Conventionally, the first turn of the portion of the spiral winding of tube 3 located in combustion chamber 25 is the turn that contacts the front 22 and is marked as 35, while the last turn of the same portion is marked as 36. Similarly, the last turn of the portion of the spiral winding of tube 3 located in condensation chamber 26 is the turn that contacts the bottom 21 and is marked as 38, while the first turn of the same portion is marked as 37.

[0016] The flow guide 6 includes a disc 61 made of insulating material, which is supported by a thin metal plate frame 62, the thin metal plate frame being provided with radially peripheral flanges 63.

[0017] The diffuser 6 is installed inside the winding 30 of the tube 3 such that its flange 63 is inserted and positioned in a hermetically sealed manner in the gap 33, which exists between the last turn 36 of the tube 3 in the combustion chamber 25 and the first turn 37 of the tube 3 in the condensation chamber 26.

[0018] The heat exchanger 1 operates as follows: The fluid to be heated (water) circulates countercurrently with the hot gas. The fluid to be heated is introduced into the last turn 38 and exits the helical winding through the first turn 35.

[0019] The hot gases generated inside the combustion chamber 25 by the burner 50 can only leave the combustion chamber from the inside out through the gap 33 (arrow i). Simultaneously, the hot gases heat the walls of the tube 3 and thus the water circulating within it. When the hot gases come into contact with the body 20 of the outer casing 2, they are directed to the condenser chamber 26 (arrow j), and then they return to the interior of the condenser chamber 26 through the gap 33, this time from the outside in (arrow k).

[0020] like Figure 1 As can be seen, due to the configuration of the flow guide 6, no hot gas passes between the last turn 36 and the flange 63 or between the first turn 37 and the flange 63.

[0021] Therefore, the heat exchange between the hot gas and the water circulating in the first turn 37 and the last turn 36 is poor, and thus the overall efficiency of the exchanger 1 is low.

[0022] Furthermore, this closure of the channel between the two turns 36 and 37 results in a pressure loss of the hot gas circulating in the outer casing 2. Summary of the Invention

[0023] Therefore, one object of the present invention is to overcome the above-mentioned disadvantages, in particular to improve the heat exchange between hot gas and water circulating in the first turn on the condenser side and the last turn on the combustion chamber side of the tube, and to increase the number of channels between the turns.

[0024] Another objective of the present invention is to reduce the pressure loss of hot gas circulating in the gaps between the turns of the tube.

[0025] For this purpose, the present invention relates to a condensing heat exchanger comprising:

[0026] - At least one tube, which is helically wound to form a helical winding, and a fluid to be heated, such as water, circulates within it. The tube is made of a material with good thermal conductivity and has a planar or substantially planar front and a planar or substantially planar rear, the two surfaces being opposite each other and perpendicular or nearly perpendicular to the axis of the helical winding. The winding is arranged to provide gaps between adjacent turns.

[0027] - An airtight housing, with the at least one pipe installed inside, the housing including a bottom and a front, a door installed on the front, and a sleeve provided for venting combustion gases.

[0028] The front of the tube faces the front of the outer casing, and the back of the tube faces the bottom of the outer casing.

[0029] - A device for supplying and / or generating hot gas inside the housing, such as a gas or oil burner, which is mounted on the door.

[0030] - A disc-shaped deflector, disposed inside the helical winding of the tube, provides a combustion chamber located between the door and the deflector on one side and a condensation chamber located between the deflector and the bottom of the casing on the other side. The deflector comprises a disc made of insulating material supported by a metal plate frame with a peripheral flange inserted into the gap between two consecutive turns of the winding. The outer diameter of the disc-shaped deflector is smaller than the inner diameter of the helical winding at the inner end of its turn, thereby providing a channel, referred to as a "hot gas circulation" channel, between the edge of the disc-shaped deflector and the inner end of the first turn of the winding in the condensation chamber.

[0031] According to the invention, the flange has a front face facing the front of the housing and a rear face facing the bottom of the housing, the two faces being opposite each other. The front face is positioned in an airtight manner against the rear of the last turn of the winding located in the combustion chamber. At least one spacer element is disposed between the rear of the flange and the front of the first turn of the winding located in the condensation chamber, thereby providing a gap between them called a "gas circulation" gap, such that the hot gases pass through the gas circulation gap radially or approximately radially from the outside to the inside, and then axially from front to back through the gas circulation passage in the direction of the condensation chamber.

[0032] Due to the features of this invention, hot gas can circulate between the last turn on the combustion chamber side of the tube and the first turn on the condensation chamber side. This improves heat exchange. Therefore, in Figure 1 and Figure 3 In the exemplary embodiment shown, there are four turns in the condensation chamber, whereas in the prior art there are only three hot gas passages between these four turns (see Figure 1 The solution of this invention now has four channels (see...). Figure 3 This means that the hot gas passage increases by 33%.

[0033] Furthermore, the creation of the gas circulation gap and the hot gas circulation channel reduces the pressure loss of the circulating gas. Therefore, the fan (not shown) that propels the air / gas mixture into the burner 50 or the fan of the hot gas supply device 5 does not need to be as powerful as fans in the prior art, and its power consumption is lower.

[0034] Other advantageous and non-limiting features according to the invention, considered individually or in combination:

[0035] - An annular shoulder extending from the inner end of the first turn of the winding located in the condenser chamber is provided in front of the first turn, and the at least one spacer element extends between the annular shoulder and the rear of the flange to form the gas circulation gap;

[0036] - An annular shoulder is provided behind the last turn of the winding in the combustion chamber. The annular shoulder extends from the inner end of the turn, and the front of the flange is provided to abut against the annular shoulder in an airtight manner.

[0037] - The spacer element consists of a protruding element, such as a stamped part, formed on the back of the flange, which abuts against the front support of the first turn of the winding located in the condenser chamber, or against the annular shoulder support on the front side, in order to provide the gas circulation gap;

[0038] - The spacer element consists of a protruding element, such as a boss, formed in the wall of the tube, which protrudes from the front of the first turn of the winding located in the condenser chamber, or from the annular shoulder of the front, and the protruding element is supported against the rear of the flange to provide the gas circulation gap;

[0039] - The spacer element is composed of a comb having teeth that are inserted between the front of the first turn of the winding located in the condensation chamber and the rear of the flange to provide the gas circulation gap;

[0040] - The metal plate frame of the disc-shaped flow guide has a circular bottom defined by an annular edge perpendicular to the bottom, so as to provide a disc-shaped cavity for receiving a disc made of insulating material and a peripheral flange protruding outward from the annular edge;

[0041] - The disc, made of insulating material, has a protruding end that protrudes from the disc-shaped cavity into the interior of the combustion chamber, and the diameter of the protruding end is equal to the inner diameter of the helical winding of the tube at the inner end of the turn of the tube, such that the lateral edge of the protruding end is in airtight contact with the inner end of the last turn of the tube in the combustion chamber, thereby preventing hot gas from passing between them.

[0042] - The exchanger comprises a single tube forming a helical winding, and the outer flange of the metal plate frame of the guide is helical;

[0043] - The exchanger includes at least two tubes that are helically wound to form at least two adjacent helical windings, one helical winding being disposed in a combustion chamber and the other helical winding being disposed in a condensation chamber, and the outer flange of the metal plate frame of the guide disposed between the two adjacent windings is annular and perpendicular to the axis of the two adjacent helical windings. Attached Figure Description

[0044] Other features, objects, and advantages of the invention will become apparent from the following description, which is purely illustrative and not restrictive, and should be read in conjunction with the accompanying drawings, wherein:

[0045] Figure 1 This is a cross-sectional view of an exemplary embodiment of a condensing heat exchanger according to the prior art.

[0046] Figure 2 yes Figure 1 A perspective view of a portion of the heat exchanger tubes.

[0047] Figure 3 This is a longitudinal sectional view of a first embodiment of a condensing heat exchanger according to the present invention.

[0048] Figure 4 This is a perspective view of a portion of the tubes located in the condenser chamber of the heat exchanger according to the present invention.

[0049] Figure 5 This is a perspective view of a first embodiment of a flow guide intended for positioning in a heat exchanger according to the invention.

[0050] Figure 6 This is a perspective view of a second embodiment of a flow guide intended for positioning in a heat exchanger according to the invention.

[0051] Figure 7 yes Figure 3 A detailed view of the lower part of the condensing heat exchanger, showing the flow guide section, the last two turns of the tubes in the combustion chamber, and the first two turns of the tubes in the condensing chamber.

[0052] Figure 8 Is with Figure 7 Similar detailed views are shown, but a second embodiment of the condensing heat exchanger according to the invention is illustrated.

[0053] Figure 9 Is with Figure 7 Similar detailed views are shown, but a third embodiment of the condensing heat exchanger according to the invention is illustrated.

[0054] Figure 10 Is with Figure 7 Similar detailed views are shown, but a fourth embodiment of the condensing heat exchanger according to the invention is illustrated.

[0055] Figure 11 Is with Figure 7 Similar detailed views are shown, but a fifth embodiment of the condensing heat exchanger according to the invention is illustrated.

[0056] Figure 12 This is a perspective view of the spacer element. Detailed Implementation

[0057] Now refer to Figure 3 A more detailed description of the heat exchanger according to the invention, designated 10. Previously combined Figure 1 and Figure 2Elements described that are common to the prior art switch 1 have the same reference numerals and will not be described in detail again.

[0058] The heat exchanger 10 differs from previous heat exchangers in the structure of the pipes near the flow guide and the structure of the flow guide itself. In this heat exchanger 10, the pipes are indicated by reference numeral 7, and the flow guide is indicated by reference numeral 8.

[0059] like Figure 3 As shown, the heat exchanger 10 may include a single tube 7 helically wound around an axis X-X' to form a helical winding 70. The tube has two ends forming an inlet and an outlet nozzle, which are not visible in the figure. The tube is made of a material with good thermal conductivity, particularly a metal (advantageously stainless steel). The fluid to be heated circulates therein.

[0060] The tube 7 has a straight, preferably rounded rectangular cross section (e.g., elliptical or elliptical or rectangular straight cross section with two flat longitudinal sides), thus having two opposing sides that are therefore planar or substantially planar, namely front 71 and rear 72, which are perpendicular or approximately perpendicular to the axis X-X' of the winding 70.

[0061] The different turns of tube 7 are spaced apart from each other by a gap 73 with a calibration width L.

[0062] The inner end of each turn of the helical winding 70 (that is, the end located inside the winding) is marked 74 and has the shape of a straight arc. The opposite outer end is also marked 75.

[0063] Use the spacer element to calibrate gap 73.

[0064] Advantageously, the gap 73 can be calibrated in the wall of the tube 7 using a boss 76 (or corrugation) formed in one of the planes of the tube 7 (e.g., the front 71 here). These bosses 76 are arranged substantially radially relative to the axis X-X'. They are identical to the bosses 34 of the tube 3. Each boss 76 supports a face abutting the adjacent turn (without a boss). These bosses have a defined height, allowing for precise calibration of the width of the gap 73.

[0065] The gap 73 can also be made of comb-like material 9 (e.g. Figure 10 and Figure 11 (One shown) is formed. This comb has a central bar 90 and vertical blades 91 (teeth of the comb). The comb 9 is arranged relative to the winding 70 such that each tooth 91 is inserted between two consecutive turns of the winding 70. Preferably, at least two combs 9 are used, arranged on both sides of the winding 70.

[0066] The first and last turns of the portion of the spiral winding 70 located in the combustion chamber 25 are marked as 701 and 702, respectively, while the first and last turns of the portion of the winding 70 located in the condensation chamber 26 are marked as 703 and 704, respectively (see...). Figure 3 ).

[0067] The flow guide 8 includes a disc 81 made of insulating material, which is supported by a thin metal plate frame 82. (As...) Figure 5 and Figure 6 As can be seen more clearly, the frame 82 has a circular bottom 820, which is defined by an annular edge 821 perpendicular to the bottom. The bottom 820 and the edge 821 together define a disc-shaped cavity 822, which is sized to receive and hold the disc 81.

[0068] In the case where the heat exchanger 10 includes a single spiral wound tube 7, the shape of the frame 82 is as follows: Figure 5 As shown, it has a flange 823 that extends substantially radially outward from the annular edge 821 and is helical. The flange 823 can therefore be inserted between two consecutive helical turns of the same tube.

[0069] The heat exchanger 10 may also include a plurality of tubes 7, each of which is spirally wound around an axis X-X' and arranged side by side such that their axes are coaxial. Thus, for example, it may have a first tube winding disposed in a condenser chamber 26, in which a first fluid to be heated circulates, and may have a second tube winding in a combustion chamber 25, in which the same first fluid or possibly a second fluid to be heated circulates.

[0070] In the case where the heat exchanger 10 includes at least two helically wound tubes 7 arranged side by side, the frame of the guide tube is slightly different from the previous one. It is designated as 82', and... Figure 6 As shown in the figure, it has an annular flange 823', which extends radially outward from an annular edge 821. The edge 821 thus has a constant height. The flange 823' is perpendicular to the axis X-X'.

[0071] Different embodiments of the invention will now be described, which enable the flow guide 8 to be positioned on the tube 7 while providing space for gas passage between the flow guide and the first turn of the tube 7 located in the condensation chamber 26.

[0072] For simplicity, these different embodiments only describe the case where the heat exchanger 10 includes a single winding 70 and the flow guide 8 includes a frame 82, as shown below. Figure 5As shown. However, all these embodiments can also be implemented with at least two different windings, one installed in the combustion chamber 25 and the other installed in the condenser chamber 26, on both sides of the diffuser 8, which includes a frame 82', as shown. Figure 6 As shown.

[0073] Now refer to Figures 3 to 5 and Figure 7 The first embodiment of the flow guide 8 and the tube 7 is described in more detail.

[0074] The front 71 of the first turn 703 has an annular shoulder 77. This shoulder is annular because it extends around the first turn 703 (see...). Figure 4 ).

[0075] The annular shoulder 77 preferably extends from the inner end 74 between one-third and half of the height H of the first turn 703. Therefore, the width L1 intercepted at the level of the shoulder 77 between the rear 72 of the last turn 702 and the front 71 of the first turn 703 is greater than the width L of the gap 73.

[0076] Due to the presence of the shoulder 77, the bosses (marked as 76') located on the front 71 of the first turn 703 are slightly offset towards the outer side of the turn where the shoulder 77 is not present. These bosses 76' are positioned due to the cutting plane. Figure 7 Invisible in the middle, but in Figure 3 and Figure 4 As can be seen, boss 76' supports abut against the rear 72 of the last turn 702.

[0077] The tube 7 is advantageously obtained by hydroforming, which allows for the manufacture and precise positioning of the shoulder 77 and the bosses 76, 76'.

[0078] The flange 823 of the frame 82 has a front face 8231 facing the front face 22 and an opposite rear face 8232. The rear face 8232 has at least one protruding element 8233 (e.g., a pin-shaped element), preferably multiple pins. These pins are advantageously obtained by stamping the front face 8231. They are preferably evenly distributed over the entire periphery of the flange 823 and function as spacers.

[0079] A flow guide 8 is installed inside the winding 70 such that a flange 823 is inserted between the rear 72 of the last turn 702 and the shoulder 77 of the first turn 703, and a protruding element 8233 is supported against the shoulder 77, thereby providing a gas circulation gap 73' between the shoulder 77 and the rear 72 of the last turn 702. Furthermore, the insertion of the flange 823 causes its front end 8231 to be hermetically positioned (pressed) against the rear 72 of the plane of the last turn 702. The flange 823 is thus sandwiched between two consecutive turns 702 and 703. Hot gas circulates radially from the outside to the inside of the winding 70 in this gas circulation gap 73' (see...). Figure 3 (arrow m in the image).

[0080] Furthermore, the outer diameter D1 of the guide 8, cut horizontally at the outer surface of the edge 821, and more specifically, the outer diameter of the disc-shaped cavity 822 of the frame 82, is smaller than the inner diameter D2 of the helical winding 70 measured at the inner end 74 of the turn, so as to provide an axial annular channel between the edge 821 and the inner end of the first turn 703, referred to as the "gas circulation channel" 27. Hot gas circulates axially from front to back in this channel 27 (see...). Figure 3 (arrow n in the image).

[0081] The gas circulation channel 27 connects the gas circulation gap 73' to the condenser chamber 26. Therefore, contrary to the prior art, hot gas can circulate between the last turn 702 and the first turn 703, thereby increasing heat exchange with the fluid to be heated (e.g., water) circulating in the tube 7.

[0082] Advantageously, the disc 81, made of insulating material, is thicker than the annular edge 821, and therefore has a protruding end 810 projecting in the direction toward the combustion chamber 25 (see...). Figure 3 Advantageously, the protruding end 810 has a diameter D3, which is equal to the inner diameter D2 of the helical winding 70, such that the lateral edge 811 of the end 810 contacts the inner end 74 of the last turn 702, thereby preventing hot gas from passing through at that position.

[0083] Furthermore, it should be noted that the shoulder 77 facing the flange 823 allows for a constant rolling space between it and the last turn 702, which is not reduced due to the thickness of the metal plate of the flange 823.

[0084] Now refer to Figure 8 A second embodiment of the guide vane 8 and tube 7 is described in more detail.

[0085] This embodiment differs from the first embodiment in that the flange 823 does not have any protruding elements, and on the other hand, the first turn 703 has at least one protruding element 770 (spacer) formed on the annular shoulder 77, preferably multiple protruding elements. These protruding elements 770 are preferably radially and uniformly arranged on the shoulder 77. As described above, the front end 8231 of the flange 823 is hermetically positioned (pressed) against the rear end 72 of the plane of the last turn 702. Furthermore, the protruding elements 770 (preferably bosses) abut against the rear end 8232 of the flange 823, which allows for the provision of a gas circulation gap 73'.

[0086] Now refer to Figure 9 A third embodiment of the guide vane 823 and tube 7 is described. It is consistent with reference to... Figure 7 The difference in the first embodiment described is that the rear end 72 of the last coil 702 on the combustion chamber side has an annular shoulder 78. Preferably, the annular shoulder 78 extends from the inner end 74 between one-third and half of the height H of the last coil 702. The front end 8231 of the flange 823 is positioned hermetically against the annular shoulder 78, and the height of the protruding element 8233 is correspondingly adapted to contact the shoulder 77.

[0087] Now refer to Figure 10 A fourth embodiment describing the flange of the flow guide 8 and the tube 7.

[0088] It and Figure 9 The difference in the third embodiment is that the flange 823 does not include the protruding element 8233, and the first turn 703 does not include the shoulder 77 but on the other hand includes the protruding element 770.

[0089] It is readily understood that, provided there is a circulation space, different embodiments can be combined by providing shoulder 77 and / or shoulder 78 and different spacing elements (protruding element 8233 and / or protruding element 770).

[0090] Finally, now we will refer to Figure 11 and Figure 12 The fifth embodiment is described. The comb 9 described above is also used to form a gas circulation gap 73'. In this case, on the condenser chamber 26 side, one of its teeth 91 is inserted (clamped) between the rear end 8232 of the flange 823 and the front end 71 of the first turn 703, while the flange 823 abuts against the rear end 72 of the last turn 702 in an airtight manner.

Claims

1. A condensing heat exchanger (10), comprising: - At least one tube (7) is helically wound to form a helical winding (70) in which the fluid to be heated circulates. The tube (7) is made of a thermally conductive material and has a planar or substantially planar front end (71) and a planar or substantially planar rear end (72) opposite to each other and perpendicular or approximately perpendicular to the axis (X-X') of the helical winding (70). The winding is arranged to provide a gap (73) between adjacent turns. - An airtight housing (2), wherein at least one pipe (7) is installed inside the housing, the housing (2) includes a bottom (21) and a front (22), a door (4) is installed on the front, the housing (2) is provided with a sleeve (23) for venting combustion gases, the front (71) of the pipe (7) faces the front (22) of the housing (2), and the rear (72) of the pipe (7) faces the bottom (21) of the housing (2). - A device (5) for supplying and / or generating hot gas inside the housing, the device being mounted on the door (4), - A disc-shaped deflector (8), disposed inside the helical winding (70) of the tube, provides a combustion chamber (25) located between the door (4) and the deflector (8) inside the housing (2) on the one hand, and a condensation chamber (26) located between the deflector (8) and the bottom (21) of the housing on the other hand. The deflector (8) includes a disc (81) made of insulating material, which is supported by a metal plate frame (82) provided with peripheral flanges (823, 823') inserted into the gap between two consecutive turns of the winding (70). The outer diameter (D1) of the disc-shaped deflector (8) is smaller than the inner diameter (D2) of the helical winding (70) cut off at the inner end (74) of its turn, thereby providing a gas circulation passage (27) between the edge of the disc-shaped deflector (8) and the inner end (74) of the first turn (703) of the winding in the condensation chamber (26). The flange (823, 823') is characterized by having a front face (8231) facing the front surface (22) of the housing (2) and a rear face (8232) facing the bottom (21) of the housing (2), the two faces being opposite to each other, the front face (8231) being positioned in an airtight manner against the rear face (72) of the last turn (702) of the winding (70) located in the combustion chamber (25), wherein at least one spacer element is disposed between the rear face (8232) of the flange (823, 823') and the front face (71) of the first turn (703) of the winding (70) located in the condensing chamber (26), thereby providing a gas circulation gap (73') between them, such that the hot gases pass through the gas circulation gap (73') radially or approximately radially from the outside to the inside, and then axially from front to back through the gas circulation channel (27) in the direction of the condensing chamber (26).

2. The heat exchanger (10) according to claim 1, characterized in that, The front (71) of the first turn (703) of the winding (70) located in the condenser chamber (26) is provided with an annular shoulder (77) extending from the inner end (74) of the turn, and wherein the at least one spacer element extends between the annular shoulder (77) and the rear (8232) of the flange (823, 823') to form the gas circulation gap (73').

3. The heat exchanger (10) according to claim 1, characterized in that, An annular shoulder (78) is provided at the rear (72) of the last turn (702) of the winding located in the combustion chamber (25), the annular shoulder extending from the inner end (74) of the turn, wherein the front (8231) of the flange (823, 823') is provided against the annular shoulder (78) in an airtight manner.

4. The heat exchanger (10) according to claim 1, characterized in that, The spacer element consists of a protruding element (8233) formed on the rear (8232) of the flange (823, 823'), which abuts against the front (71) of the first turn (703) of the winding in the condenser chamber (26) or against the annular shoulder (77) of the front (71) to provide the gas circulation gap (73').

5. The heat exchanger (10) according to claim 1, characterized in that, The spacer element consists of a protruding element (770) that protrudes from the front (71) of the first turn (703) of the winding (70) located in the condenser chamber (26), or from the annular shoulder (77) of the front (71), and wherein the protruding element (770) is supported against the rear (8232) of the flange (823, 823') to provide the gas circulation gap (73').

6. The heat exchanger (10) according to claim 1, characterized in that, The spacer element consists of a comb (9) having teeth (91) between the front (71) of the first turn (703) of the winding (70) located in the condenser chamber (26) and the rear (8232) of the flange (823, 823') to provide the gas circulation gap (73').

7. The heat exchanger (10) according to claim 1, characterized in that, The metal plate frame (82) of the disc-shaped flow guide (8) has a circular bottom (820) defined by an annular edge (821) perpendicular to the bottom to provide a disc-shaped cavity (822) for receiving a disc (81) made of insulating material, wherein the peripheral flange (823, 823') protrudes outward from the annular edge (821).

8. The heat exchanger (10) according to claim 7, characterized in that, The disc (81) made of insulating material has a protruding end (810) that protrudes from the disc-shaped cavity (822) into the interior of the combustion chamber (25), and wherein the diameter (D3) of the protruding end (810) is equal to the inner diameter (D2) of the helical winding (70) of the tube at the inner end (74) of the turn of the tube, such that the lateral edge (811) of the protruding end (810) is in airtight contact with the inner end (74) of the last turn (702) of the tube in the combustion chamber (25), thereby preventing hot gas from passing between them.

9. The heat exchanger (10) according to claim 1, characterized in that, The heat exchanger includes a single tube (7) forming the helical winding (70), and wherein the outer flange (823) of the metal plate frame (82) of the flow guide (8) is helical.

10. The heat exchanger (10) according to claim 1, characterized in that, The heat exchanger includes at least two tubes (7) that are spirally wound to form at least two adjacent spiral windings (70), one spiral winding being disposed in a combustion chamber (25) and the other spiral winding being disposed in a condensation chamber (26), wherein the outer flange (823') of the metal plate frame (82) of the guide disposed between the two adjacent windings (70) is annular and perpendicular to the axis (X-X') of the two adjacent spiral windings (70).

11. The heat exchanger (10) according to claim 1, characterized in that, The device (5) for supplying and / or generating hot gas inside the housing is a gas or oil burner (50).

12. The heat exchanger (10) according to claim 4, characterized in that, The protruding element (8233) is a stamped part.

13. The heat exchanger (10) according to claim 5, characterized in that, The protruding element (770) is a boss formed in the wall of the tube (7).

Images