Water heater

Abstract

The water heater 10 comprises a water tank 12 having a water tank wall 14. The water heater 10 further comprises a vacuum vessel 20 enclosing a vacuum space V. The water tank 12 is entirely contained within the vacuum space V, and the entire water tank wall 14 is bounded by a vacuum. The vacuum vessel 20 comprises a vacuum vessel wall 22 consisting of several vacuum vessel wall sections gas-tightly connected to one another by welding or soldering. The water heater 10 further comprises at least one functional pipe 100, 200, 300, 400, 500 extending through the water tank wall 14 and gas-tightly connected to the water tank wall 14 at a water tank wall connection 18. The functional pipe 100, 200, 300, 400, 500 also extends through the vacuum vessel wall 22 and gas-tightly connected to the vacuum vessel wall 22 at a vacuum vessel wall connection 24.

Description

[Technical field]

[0001] The present invention relates to a water heater for heating and maintaining hot water at a desired temperature, the water heater being connectable to a public water supply and to a kitchen tap. [Background technology]

[0002] EP1173715 describes a water heater comprising a hot water tank and vacuum insulation. The structure of the water heater described therein is particularly suitable for storing pressurized water at a temperature above 100° C., and when releasing the stored water, for example via a drain tap, instantaneously boiled water is released. In the hot water tank there is an electric heating element which heats the water and keeps it at the desired temperature. Also provided are a temperature sensor, a water supply pipe connectable to the public water system, and a water discharge pipe connectable, for example, to a drain tap. In EP1173715, a flange is provided on the upper side of the water tank, on which a removable cover is bolted. On top of the removable cover, the water heater comprises an insulating material which minimizes heat loss through the cover. To further limit heat loss at the top between the hot tank and the cold outer jacket, the connection between the reservoir and the jacket is realized as a thin-walled ring-shaped collar, by which the tank is connected to the jacket in a suspended manner. The thermal resistance of the collar limits direct heat conduction losses between the hot tank and the cold jacket. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] European Patent No. 1173715 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention aims to provide a water heater that has even better efficiency than the water heaters known from the prior art, i.e. a water heater in which less heat is lost when keeping the hot water in the water tank of the water heater at the storage temperature. [Means for solving the problem]

[0005] To achieve this object, the present invention provides a water heater as claimed in claim 1. More specifically, the present invention provides a water heater comprising: a water tank having a water tank wall; A heating element contained in the water tank; a vacuum vessel enclosing a vacuum space, the water tank being entirely contained in the vacuum space, the entire water tank wall being bounded by a vacuum, the vacuum vessel comprising a vacuum vessel wall consisting of several vacuum vessel wall sections gas-tightly connected to each other by welding or soldering; at least one functional pipe extending through the water tank wall and gas-tightly connected thereto at the location of the water tank wall connection, the functional pipe also extending through the vacuum vessel wall and gas-tightly connected thereto at the location of the vacuum vessel wall connection; To provide a water heater comprising:

[0006] In the water heater according to the present invention, the water tank is entirely surrounded by a vacuum jacket. This is in contrast to the water heater described in the background section, in which a heat insulating material is placed on the cover of the water tank and there is no vacuum jacket. With the configuration according to the present invention, good insulation is still obtained, which results in less heat loss. Also, since the tank is entirely surrounded by a vacuum space, there is no heat conduction loss of the collar-shaped connection between the tank and the vacuum jacket of the water heater described in the background section.

[0007] Furthermore, the water heater according to the present invention has a more compact, simplified and lighter construction thanks to the cover, the collar-shaped connection between the tank and the vacuum jacket, and the associated required redundancy of insulating material above the cover of the water heater as described in the background art section.

[0008] In addition, by virtue of its simplified construction, the water heater according to the invention consists almost entirely of metal parts, as a result of which it is properly and sustainably recyclable and can be produced at low cost.

[0009] The water heater according to the invention is particularly advantageous when a so-called boiling water heater is used. In this case, the volume is typically at most 20 liters, more specifically, the volume is preferably in the range of 3 to 8 liters. The holding temperature of the water in the tank is at least 90°C, preferably in the range of 105°C to 108°C. The pressure in the vacuum space is preferably 10 -4 mbar, preferably at least 10 -5 mbar.

[0010] If the water tank volume is, for example, 3 liters and the holding temperature is 108°C, the water heater according to the present invention can achieve a heat loss of the hot water tank of approximately 2 W, of which 0.5 W is conductive loss and 1.5 W is radiative loss.

[0011] In an embodiment, the water tank may be supported exclusively by the at least one functional pipe.

[0012] By functional pipes we mean pipes which must be present anyway to perform a function other than supporting the water tank. A functional pipe can be, for example, a water supply pipe or a water discharge pipe. It can also be a pipe for containing certain components therein, such as an electric cable, an electric heating element and / or a temperature sensor. Such pipes must extend inside the water tank and therefore must also penetrate the vacuum vessel wall. As a result, these pipes form a thermal conduction path from the water tank to the vacuum vessel wall. However, the presence of some of these functional pipes is necessary, and by equipping them now with yet another second function, namely the function of supporting or supporting the water tank in the vacuum vessel, there is no extra thermal conduction bridge created between the water tank wall and the vacuum vessel wall due to this second function.

[0013] In an embodiment, the weight of the water tank can be transferred to the vacuum vessel wall via at least one functional pipe. Furthermore, in this embodiment, the vacuum vessel wall can serve as a support for the entire water heater on a flat surface / plane. In an alternative embodiment, it is also possible to connect the functional pipe to a fixed object in the outside world, and the weight of the water heater is transferred directly to the fixed object in the outside world via at least one functional pipe.

[0014] A portion of at least one functional pipe extending between the water tank wall connection and the vacuum vessel wall connection has a heat transport length l for heat conduction from the water tank wall connection to the vacuum vessel wall connection. h Determine the wall cross-sectional area A. When ribbed or bellows-shaped functional pipes are used, the heat transport length l h can be longer than the pipe length. In an embodiment, the heat transfer length l in mm h and mm 2 The ratio between the wall cross-sectional area A in units is given by the formula l h >4mm -1If the ratio of heat transport distance / wall cross-sectional area is within this range, the heat conduction through the at least one functional pipe may be limited such that heat loss by heat conduction through the at least one functional pipe is practically negligible.

[0015] A heat transfer length l of at least one functional pipe extending between the water tank wall connection and the vacuum vessel wall connection that is longer than 60 mm. h Similar small heat losses can be achieved by the embodiment having the above structure. In addition, the material of the at least one functional pipe is preferably stainless steel or a similar metal having a relatively low thermal conductivity coefficient. Indeed, when the wall thickness of the stainless steel functional pipe is in the range of 0.4 to 1.0 mm and the diameter is less than 8 mm, the heat conduction through the at least one functional pipe from the water tank to the vacuum vessel wall can be negligible.

[0016] The water tank may comprise a cylindrical water tank sidewall and the vacuum vessel may comprise a cylindrical vacuum vessel sidewall. To still further increase the efficiency of the water heater, in embodiments, a laminate of reflective foil and fiberglass cloth may be included at least between the cylindrical water tank sidewall and the cylindrical vacuum vessel sidewall.

[0017] Further details of the invention are set out in the dependent claims and will be further clarified hereinafter with reference to one or more exemplary embodiments in the drawings. [Brief description of the drawings]

[0018] [Figure 1] 1 illustrates a cross-sectional view of a first embodiment of a water heater; [Diagram 2] 1A and 1B illustrate diagrammatically a cross-sectional view of a second embodiment of a water heater; [Diagram 3] FIG. 2 shows a schematic cross-sectional view of a third embodiment of a water heater; [Figure 4] 4 illustrates an example of the embodiment depicted diagrammatically in FIG. 3; [Diagram 5] 5 shows a perspective cross-sectional view of the embodiment from FIG. 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] In the following detailed description, corresponding parts of different embodiments are designated by the same reference numerals. The detailed description does not relate exclusively to the examples depicted in the drawings. The reference numerals specified in the detailed description and claims do not have a limiting effect, but are merely for the purpose of clarity by referring to the examples depicted in the drawings of the various embodiments discussed in the detailed description.

[0020] In the most general terms, the invention relates to a water heater 10 comprising a water tank 12 with a water tank wall 14. The water tank 12 includes a heating element 28. The water heater 10 further comprises a vacuum vessel 20 enclosing a vacuum space V. The water tank 12 is entirely contained in the vacuum space, and the entire water tank wall 14 is bounded by a vacuum. The vacuum vessel 20 comprises a vacuum vessel wall 22 consisting of several vacuum vessel parts connected to each other gas-tight by welding or soldering. Furthermore, the water heater 10 comprises at least one functional pipe 100, 200, 300, 400, 500 extending through the water tank wall 14 and gas-tightly connected with the water tank wall 14 at the location of the water tank wall connection 18. The functional pipe 100, 200, 300, 400, 500 also extends through the vacuum vessel wall 22 and is gas-tightly connected with the vacuum vessel wall 22 at the location of the vacuum vessel wall connection 24.

[0021] It will be understood that the advantages of the water heater set forth above in the most general terms have been previously described in the Summary of the Invention and the advantages described therein are incorporated herein by reference.

[0022] In an embodiment, an example of which is diagrammatically represented in Figure 1, the water tank 12 may be supported by several supports 16. Preferably, these supports 16 are realized in a material that conducts heat poorly and that also releases as little gas as possible so as not to disturb the vacuum in the vacuum space V. Furthermore, it is preferable that the contact area between the supports 16 and the water tank 12 is as small as possible in order to limit the heat conduction through the supports 16 to a minimum.

[0023] As already described in the Summary of the Invention above, in an embodiment, an example of which is illustrated in Figures 2 to 4, the water tank 12 may be supported exclusively by at least one functional pipe 100, 200, 300, 400 and / or 500. Additionally, in a further elaboration of this embodiment, the weight of the water tank 12 may be transferred to the vacuum vessel wall 22 via at least one functional pipe 100, 200, 300, 400 and / or 500.

[0024] The portion of at least one functional pipe 100, 200, 300, 400 and / or 500 extending between the water tank wall connection 18 and the vacuum vessel wall connection 24 has a heat transport length l h and wall cross-sectional area A. In an embodiment, the heat transfer length l in mm h and mm 2 The ratio between the wall cross-sectional area A in units is given by the formula l h >4mm -1 can be satisfied.

[0025] In an embodiment, a portion of at least one functional pipe 100, 200, 300, 400 and / or 500 extending between the water tank wall connection 18 and the vacuum vessel wall connection 24 has a heat transport length l that is greater than 60 mm. h In addition, the material of the at least one functional pipe is preferably one of stainless steel, titanium or Incoloy, respectively.

[0026] In an exemplary embodiment, examples of which are illustrated in Figures 1 to 5, at least one functional pipe 100, 200, 300, 400 and / or 500 may have an outer diameter of less than 8 mm.

[0027] In addition, it is preferred that at least one of the functional pipes 100, 200, 300, 400 and / or 500 has a wall thickness between 0.4 and 1.0 mm.

[0028] In an embodiment, the water tank wall connection 18 between the at least one functional pipe and the water tank wall, and the vacuum vessel wall connection 24 between the at least one functional pipe and the vacuum vessel wall, described above, may be a welded joint.

[0029] In an alternative embodiment, the water tank wall connection 18 between the at least one functional pipe and the water tank wall, and the vacuum vessel wall connection 24 between the at least one functional pipe and the vacuum vessel wall may be soldered joints.

[0030] In an embodiment, examples of which are illustrated in Figures 1 to 5, the at least one functional pipe 100, 200, 300, 400 and / or 500 may comprise at least one of a water supply pipe 100, a water discharge pipe 200, an electric heating element containing pipe 300, 400, and a temperature sensor containing pipe 500.

[0031] 1-5, the water tank 12 may comprise a cylindrical water tank sidewall and the vacuum vessel 20 may include a cylindrical vacuum vessel sidewall. Additionally, a laminate of reflective foil and fiberglass cloth may be included at least between the cylindrical water tank sidewall and the cylindrical vacuum vessel sidewall to reduce radiation losses.

[0032] A good reduction in radiation losses is obtained, for example, when the stack comprises at least three layers of reflective foil and at least three layers of fiberglass cloth.

[0033] In an embodiment, examples of which are illustrated in Figures 3, 4 and 5, at least one functional pipe 100, 200, 300, 400, 500 may comprise a first pipe section 102, 202, 302, 402, 502, a first bend 104, 204, 304, 404, 504 connecting the first pipe section 102, 202, 302, 402, 502 to a second pipe section 106, 206, 306, 406, 506, and a second bend 108, 208, 308, 408, 508 connecting the second pipe section 106, 206, 306, 406, 506 to a third pipe section 110, 210, 310, 410, 510. The first pipe section 102, 202, 302, 402, 502 then extends through the top side of the vacuum vessel 20. The third pipe section 110, 210, 310, 410, 510 extends through the bottom side of the water tank 12. Furthermore, the first pipe section 102, 202, 302, 402, 502 extends substantially vertically between the water tank wall 14 and the vacuum vessel wall 22.

[0034] Such an embodiment has the advantage that the first pipe sections are particularly long and the heat transfer through these first pipe sections to the vacuum vessel wall 22 is limited over a large area.

[0035] In the embodiment, examples of which are illustrated in Figures 3, 4 and 5, at least one functional pipe a first functional pipe 100, which is a water supply pipe extending through and gas-tightly connected to the first vacuum top wall opening and extending through and gas-tightly connected to the first water tank bottom wall opening; a second functional pipe 200, which is a water discharge pipe extending through and gas-tightly connected to the second vacuum top wall opening and extending through and gas-tightly connected to the second water tank bottom wall opening; a third functional pipe 300, which is a first heating element pipe section extending through and in gas-tight connection with the third vacuum top wall opening and extending through and in gas-tight connection with the third water tank bottom wall opening; a fourth functional pipe 400, which is a second heating element pipe section extending through and gas-tightly connected to the fourth vacuum top wall opening and extending through and gas-tightly connected to the fourth water tank bottom wall opening, the third pipe 300 and the fourth pipe 400 being connected to each other via a helical pipe section 28, the third pipe 300, the fourth pipe 400 and the helical pipe section 28 forming an integral single part in which the heating element and the cable to the heating element are included; Equipped with.

[0036] Finally, the at least one functional pipe may further comprise a fifth functional pipe 500, which is a sensor pipe extending through and in gas-tight connection with the fifth vacuum top wall opening and extending through and in gas-tight connection with the fifth water tank bottom wall opening. The sensor pipe may include at least a temperature sensor and a cable to the temperature sensor.

[0037] In an embodiment, the water tank and the vacuum vessel may each have a cylindrical configuration. Additionally, the first, second, third, fourth and fifth vacuum top wall openings may each have a diameter greater than the outer diameter of the cylindrical water tank and less than the inner diameter of the cylindrical vacuum vessel 20, with the center lying on a common pitch circle whose center lies on the vertical axis of the cylindrical vacuum vessel.

[0038] The first, second, third, fourth and fifth water tank bottom wall openings, if present, according to an embodiment, each have a center that may lie on a common vertical plane.

[0039] In an embodiment, an example of which is illustrated in Fig. 5, a spacer 30 made of a material having a thermal conductivity coefficient of less than 5 W / (mK), such as, for example, a ceramic ring, may be included between the first pipe section 102, 202, 302, 402, 502 of at least one functional pipe 100, 200, 300, 400, 500 and the vacuum vessel wall 22. The spacer 30 may preferably be placed adjacent to the transition between the water tank bottom side and the water tank side wall.

[0040] In an embodiment, an example of which is illustrated in Figures 4 and 5, at least one first pipe section 102, 202, 302, 402, 502 may abut exclusively against the water tank wall 14 at the transition between the water tank bottom side and the water tank side wall.

[0041] In an embodiment, an example of which is illustrated in Figures 4 and 5, the transitions between the water tank top and the water tank sidewall and the upper portion of at least the first pipe section 102, 202, 302, 402, 502 may be spaced apart from each other.

[0042] In the embodiment, examples of which are illustrated in Figures 4 and 5, at least the upper part of the first pipe section 102, 202, 302, 402, 502 and the water tank upper side may be fixed relative to each other with the aid of fixing elements.

[0043] The fixing element may be a second spacer 32, an example of which is illustrated in Figures 4 and 5. Such a second spacer 32 may on the one hand keep the water tank 12 next to the transition between the water tank top and the water tank side wall, and on the other hand keep the upper parts of the first pipe sections 102, 202, 302, 402, 502 of at least one functional pipe 100, 200, 300, 400, 500 at a distance from each other. The second spacer 32 then engages on the one hand with the water tank and on the other hand with the upper parts of the first pipe sections 102, 202, 302, 402, 502 of at least one functional pipe 100, 200, 300, 400, 500.

[0044] In a further elaboration of this embodiment, the engagement of the second spacer 32 with the water tank 12 can be realized at the top of the water tank 12 at the location of the axis of the water tank 12. The engagement of the second spacer 32 with the upper part of the first pipe section 102, 202, 302, 402, 502 of the at least one functional pipe 100, 200, 300, 400, 500 can be realized at one upper part or at two upper parts 102, 402.

[0045] The second spacer 32 is realized in the illustrated embodiment as a thin-walled element with a small cross-sectional area so as to keep as small as possible the heat conduction through the second spacer 32 from the water tank 12 to the first pipe section 102, 402. The second spacer 32 can absorb both pressure and tension forces, which are relevant for the stability of the water tank 12 in the vacuum vessel 20 to prevent damage, especially during transportation of the water heater.

[0046] The invention is not limited to the described embodiments and examples illustrated in the drawings, in which the drawings and reference numbers are merely for the purpose of clarity and have no limiting effect, the invention is defined by the appended claims.

Claims

1. A water heater, A water tank (12) having a water tank wall (14); A heating element (28) contained in said water tank (12); a vacuum vessel (20) enclosing a vacuum space (V), the water tank (12) being entirely contained in the vacuum space (V), the entire water tank wall (14) being bounded by a vacuum, the vacuum vessel (20) comprising a vacuum vessel wall (22) consisting of several vacuum vessel wall sections gas-tightly connected to each other by welding or soldering; at least one functional pipe (100, 200, 300, 400 and / or 500) extending through said water tank wall (14) and gas-tightly connected thereto at the location of a water tank wall connection (18), said functional pipe (100, 200, 300, 400 and / or 500) also extending through said vacuum vessel wall (22) and gas-tightly connected thereto at the location of a vacuum vessel wall connection (24), said at least one functional pipe (100, 200, 300, 400, 500) comprising a first pipe section (102, 202, 302, 402, 502), a first bend (104, 204, 304, 404, 504) connecting said first pipe section (102, 202, 302, 402, 502) to a second pipe section (106, 206, 306, 406, 506), and a second bend (108, 208, 308, 408, 508) connecting said second pipe section (106, 206, 306, 406, 506) to a third pipe section (110, 210, 310, 410, 510); the first pipe section (102, 202, 302, 402, 502) extends through an upper side of the vacuum vessel (20); the third pipe section (110, 210, 310, 410, 510) extends through a bottom side of the water tank (12); The first pipe section (102, 202, 302, 402, 502) extends substantially vertically between the water tank wall (14) and the vacuum vessel wall (22).

2. 2. The water heater according to claim 1, wherein said water tank (12) is exclusively supported by said at least one functional pipe (100, 200, 300, 400 and / or 500).

3. 3. The water heater according to claim 2, wherein the weight of the water tank (12) is transferred to the vacuum vessel wall (22) via the at least one functional pipe (100, 200, 300, 400 and / or 500).

4. The part of the at least one functional pipe (100, 200, 300, 400 and / or 500) extending between the water tank wall connection (18) and the vacuum vessel wall connection (24) has a heat transport length l for heat conduction from the water tank wall connection (18) to the vacuum vessel wall connection (24). ｈ Determine the wall cross-sectional area A and the heat transfer length l in mm. ｈ and mm ２ The ratio between the wall cross-sectional area A in units is expressed by the formula l ｈ >4mm －１ The water heater according to any one of claims 1 to 3, which satisfies the above.

5. The portion of the at least one functional pipe (100, 200, 300, 400 and / or 500) extending between the water tank wall connection (18) and the vacuum vessel wall connection (24) has a heat transport length l longer than 60 mm. ｈ 5. The water heater according to claim 1, wherein the material of the at least one functional pipe is one of stainless steel, titanium or incoloy, respectively.

6. 6. The water heater according to any one of the preceding claims, wherein said at least one functional pipe (100, 200, 300, 400 and / or 500) has an outer diameter of less than 8 mm.

7. 7. The water heater according to any one of the preceding claims, wherein said at least one functional pipe (100, 200, 300, 400 and / or 500) has a wall thickness between 0.4 and 1.0 mm.

8. 8. The water heater according to claim 1, wherein the water tank wall connection (18) and the vacuum vessel wall connection (24) are welded joints.

9. 9. The water heater according to claim 1, wherein the water tank wall connection (18) and the vacuum vessel wall connection (24) are soldered joints.

10. 10. The water heater according to any one of claims 1 to 9, wherein the at least one functional pipe (100, 200, 300, 400 and / or 500) comprises at least one of a water supply pipe (100), a water discharge pipe (200), a pipe containing an electric heating element (300, 400) and a pipe containing a temperature sensor (500).

11. 11. The water heater of claim 1, wherein the water tank (12) comprises a cylindrical water tank side wall, the vacuum vessel (20) comprises a cylindrical vacuum vessel side wall, and a laminate of reflective foil and fiberglass cloth is included at least between the cylindrical water tank side wall and the cylindrical vacuum vessel side wall.

12. 12. The water heater of claim 11, wherein the laminate comprises at least three layers of reflective foil and at least three layers of fiberglass cloth.

13. The at least one functional pipe comprises: a first functional pipe (100) which is a water supply pipe extending through and gas-tightly connected to the first vacuum top wall opening and extending through and gas-tightly connected to the first water tank bottom wall opening; a second functional pipe (200) which is a water discharge pipe extending through and gas-tightly connected to the second vacuum top wall opening and extending through and gas-tightly connected to the second water tank bottom wall opening; a third functional pipe (300) which is a first heating element pipe section extending through and in gas-tight connection with the third vacuum top wall opening and extending through and in gas-tight connection with the third water tank bottom wall opening; a fourth functional pipe (400) which is a second heating element pipe section extending through and gas-tightly connected to a fourth vacuum top wall opening and extending through and gas-tightly connected to a fourth water tank bottom wall opening, said third functional pipe (300) and said fourth functional pipe (400) being connected to each other via a helical pipe section (28), said third functional pipe (300), said fourth functional pipe (400) and said helical pipe section (28) forming an integral single part in which the heating element and the cable to said heating element are included; a fifth functional pipe (500) which is a sensor pipe extending through and gas-tightly connected to the fifth vacuum top wall opening and extending through and gas-tightly connected to the fifth water tank bottom wall opening, said sensor pipe including at least a temperature sensor and a cable to said temperature sensor; The water heater according to any one of claims 1 to 12, comprising:

14. 14. The water heater of claim 13, wherein the water tank (12) and the vacuum vessel (20) each have a cylindrical configuration, and the first, second, third, fourth and fifth vacuum upper wall openings each have a diameter greater than an outer diameter of the cylindrical water tank (12) and less than an inner diameter of the cylindrical vacuum vessel (20), and have centers located on a common pitch circle whose center is located on a vertical axis of the cylindrical vacuum vessel (20).

15. 15. The water heater according to claim 13 or 14, wherein the first, second, third, fourth and fifth water tank bottom wall openings each have a center located on a common vertical plane.

16. 16. The water heater according to claim 1, further comprising a first spacer (30) made of a material having a thermal conductivity coefficient of less than 5 W / (m.K), such as a ceramic ring, between the first pipe section (102, 202, 302, 402, 502) of the at least one functional pipe (100, 200, 300, 400, 500) and the vacuum vessel wall (22).

17. 17. The water heater according to any one of claims 1 to 16, wherein the at least first pipe section (102, 202, 302, 402, 502) abuts exclusively against the water tank wall (14) at the transition between the water tank bottom side and the water tank side wall.

18. 18. The water heater according to claim 16 or 17, wherein the transitions between the water tank upper side, the water tank side wall and the upper part of the at least first pipe section (102, 202, 302, 402, 502) are located at a distance from each other.

19. 19. The water heater according to claim 18, wherein the upper part of the at least first pipe section (102, 202, 302, 402, 502) and the water tank upper side are fixed relative to each other with the aid of a fixing element.

20. 20. The water heater according to claim 19, wherein the fixing element is realized as a second spacer (32) which, on the one hand, keeps the water tank (12) next to the transition between the water tank upper side and the water tank side wall and, on the other hand, keeps the upper parts of the first pipe parts (102, 202, 302, 402, 502) of the at least one functional pipe (100, 200, 300, 400, 500) at a distance from each other, engaging with the water tank (12) on the one hand and engaging with the upper part of the first pipe part (102, 202, 302, 402, 502) of the at least one functional pipe (100, 200, 300, 400, 500) on the other hand.

21. The water heater according to claim 20, wherein the engagement of the second spacer (32) with the water tank (12) is realized on the upper side of the water tank (12) at the location of the axis of the water tank, and the engagement of the spacer with the upper part of the first pipe section (102, 202, 302, 402, 502) of the at least one functional pipe (100, 200, 300, 400, 500) is realized in one upper part or two upper parts (102, 402).

22. The water heater of claim 1, wherein the pressure in the vacuum space (V) is 10 −4 mbar.

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