CN111629461B

CN111629461B - Safety temperature limiter for fluid contact side

Info

Publication number: CN111629461B
Application number: CN202010129120.7A
Authority: CN
Inventors: C.科克
Original assignee: Golders Holdings Co ltd
Current assignee: Golders Holdings Co ltd
Priority date: 2019-02-28
Filing date: 2020-02-28
Publication date: 2024-03-12
Anticipated expiration: 2040-02-28
Also published as: EP3702693A1; PL3702693T3; EP3702693B1; CN111629461A

Abstract

The utility model relates to a continuous heater (10) for heating a liquid, comprising: a heating cartridge (11) having at least one channel, wherein the at least one channel is a fluid-flowing channel (11), wherein at least one electrically heated heating element provided for heating a liquid is arranged in the fluid-flowing channel (12); and at least one safety temperature limiter (12) which is provided to switch at least one heating element to no voltage by means of a temperature-controlled switching element (14) when a predetermined maximum temperature of the liquid is exceeded, wherein the safety temperature limiter (12) comprises a coupling element (13) which is provided for transferring heat from the liquid to the switching element (14) and has a fluid contact side, wherein the coupling element (13) is arranged to be at least partially in contact with the liquid, wherein the coupling element (13) has at least one recess (16) forming a cavity on the fluid contact side.

Description

Safety temperature limiter for fluid contact side

Technical Field

The present utility model relates to a continuous heater for heating a liquid, comprising: a heating cartridge having at least one fluid-circulating channel, wherein at least one electrically heated heating element provided for heating the liquid is arranged in the fluid-circulating channel; and at least one safety temperature limiter provided for switching at least one heating element to no voltage by means of a temperature-controlled switching element when a predetermined maximum temperature of the liquid is exceeded, wherein the safety temperature limiter comprises a coupling element having a fluid contact side provided for transferring heat from the liquid to the switching element, wherein the coupling element is arranged such that it is at least partially in contact with the liquid.

Background

Such continuous heaters are well known from the prior art. In the continuous heater described at the outset, the water to be heated is led through a heating cartridge having at least one fluid-flowing channel. A heating device is located in at least one of the channels through which the fluid flows, which heating device is heated by means of an electric current and thus serves to heat the liquid. In general, heating coils or heating wires, in particular bare wire heating coils, are used as heating means which are in direct contact with the liquid to be heated without further insulation. In many countries, the operating requirements of such continuous heaters are that they are provided with automatic shut-off devices, commonly referred to as safety temperature limiters, simply "STBs". In the known continuous heaters, the STB is usually designed such that it automatically switches off the continuous heater or the heating element located therein, that is to say either the continuous heater or the heating element located therein is switched to no voltage, when a defined actual or maximum temperature of the liquid in the heating cartridge is exceeded. When there is a technical failure in the heating device or in the switching device for controlling/regulating the heating device, an automatic shut-off is first considered, and the liquid flow is disturbed or interrupted. As a result, the maximum permissible temperature of the area of the heating device and/or the heating cartridge may be exceeded, whereby the components mentioned may be damaged. By switching at least the heating device and/or the entire continuous heater without voltage, on the one hand, this is reliably prevented and, on the other hand, the occurrence of a technical failure is signaled by an automatic shut-off. Subsequent damage to the environment surrounding the device or continuous heater is avoided by triggering the STB and switching off the heating device in connection therewith.

The triggering of a conventional STB generally requires a certain period of time, since depending on the arrangement of the STB in the continuous heater, triggering can only take place if a defined actual or maximum temperature is present at the location provided for this purpose on the respective STB. However, the use of an STB should ideally be helpful in that technical faults occurring on the continuous heater can be eliminated and the continuous heater can be used as prescribed to heat the liquid, re-eliminating the source of the fault and/or disturbances without causing irreparable damage to the equipment. For this purpose, it is necessary to achieve a cut-off which is as rapid as possible when a defined actual or maximum temperature is exceeded. The heat transfer between the coupling element and the switching element is already known from conventional STBs. Furthermore, temperature-controlled switching elements, such as for example bimetallic switches, are known from the prior art.

German patent document DE 298,255 U1 discloses a continuous heater with an overheat protection device corresponding to the STB, wherein the overheat protection device protrudes from the outside of the heating block into the heated water channel section, wherein the temperature is detected directly inside the water channel section. In this way, a very short response duration of the protection switching-off device should be achieved.

However, a disadvantage of this case is that the overheat protection means arranged directly inside the water channel section are also mounted in the immediate vicinity of the heating element. In this case, for example, an undesired switching off of the continuous heater can occur if there is insufficient throughflow inside the water channel section and local overheating occurs in the region of the STB. Furthermore, there is a risk in the vicinity of the space between the heating element and the overheat protection that, instead of measuring the actual temperature of the flowing liquid, the higher temperature level of the bare wire heating coil is indirectly detected. In this way, the temperature which is actually decisive for the cutting is only detected inaccurately, which in turn may lead not only to premature switching off of the continuous heater or the heating device, but also to delayed switching off. To avoid this problem, DE 298 25 255 U1 proposes that two temperature sensors are preferably arranged inside the water channel section and that the STB function is implemented as a function of the two detected temperatures. Furthermore, a continuous heater is known from DE 10 2007 052 934 A1, in which a temperature transmitter for determining the water temperature in a through-flow channel is arranged completely outside the through-flow channel. The temperature transmitter is not in direct contact with the liquid to be heated. In this way, for example by reducing corrosion of the temperature transmitter, the determination of the temperature of the liquid to be heated should be simplified and carried out more reliably. However, this arrangement of the temperature transmitter has the disadvantage that the temperature measurement for determining the maximum temperature and thus the switching off of the continuous heater does not take place with the required rapidity. The wall of the through-flow channel has a specific heat capacity in addition to its thermal resistance itself, which results in the actually occurring maximum temperature being recorded correspondingly delayed in time. The delayed shut down of the STB may result in irreparable damage to the continuous heater. In addition, in the case of external positioning of the temperature transmitter, additional fixing must be provided for this, which in turn entails high production costs.

Disclosure of Invention

The object of the present utility model is therefore to provide a continuous heater which is equipped with a safety temperature limiter which ensures a reliable safety shut-off when the maximum temperature is exceeded on the one hand and which reacts as little time delay as possible on the other hand.

This object is achieved in that the coupling element has at least one recess on the fluid contact side, which recess forms a cavity. Having a cavity-forming recess on the coupling element forming the component of the STB provides the advantage that the continuous heater can be switched off reliably and quickly when the maximum temperature is exceeded. More precisely, a rapid heat transfer between the coupling element and the temperature-controlled switching element is possible by means of the recess of the coupling element which is arranged on the fluid contact side and forms the cavity. The cavity provides a large internal surface for circumferential flushing with liquid, thereby achieving a faster heat absorption. In other words, the cavity forms the largest possible thermal coupling surface. Additionally, the specific heat capacity of the coupling element is significantly reduced with respect to the solid body by the material recess by means of the cavity. In this way, the temperature change is transmitted significantly faster through the coupling element, since the inherent thermal capacity of the coupling element is smaller. On the other hand, the spacing between the coupling element and the switching element is reduced by the recess forming the cavity. The absorbed heat can thus be transferred more quickly to the switching element, which thereby switches the continuous heater to no voltage more quickly when needed, i.e. when the maximum temperature is exceeded. The cavity of the recess can be configured in various ways, for example with different geometries, diameters or depths. The utility model also provides a reliable cut-off device having only one single coupling element for heat transfer, without other electronic components.

The fluid contacting side of the coupling element is arranged so as to be at least partially in contact with the liquid. This is achieved in that the coupling element is arranged on the fluid-carrying channel so as to form a closed fluid space with the channel. Preferably, the coupling element is inserted into an opening provided in the fluid-circulating channel, thereby forming a closed fluid space. Furthermore, the coupling element comprises a side facing away from the fluid, which side is free of a contact area for the liquid of the channel in fluid communication.

The heating cartridge preferably comprises a plurality of fluid-conducting channels, wherein an electrically heated heating element is arranged in at least one of the fluid-conducting channels. It is not necessary that an electrically heated heating element be preferably arranged in each of the fluid-carrying channels. In this case, the electrically heated heating elements provided for heating the liquid may also be arranged only in a partial region of the fluid-flow channels for heating the liquid, or alternatively one or more electrically heated heating elements may be arranged in each of the fluid-flow channels.

A further advantageous embodiment of the utility model is characterized in that the heating cartridge comprises a plurality of channels for fluid flow arranged in series, and the coupling element is arranged in the last channel of the channels for fluid flow on the respective outlet side with respect to the flow direction. The positioning of the coupling element in the last channel on the outlet side has the advantage that the fluid generally has the highest temperature here, which results in a reliable switching off of the continuous heater when a predetermined maximum temperature is reached. Furthermore, it is ensured in this way that the maximum temperature occurring in the heating cartridge is always detected. Alternatively, the coupling element may be arranged in one of the fluid-conducting heating channels at other locations. In the sense of the present utility model, a fluid, alternatively also referred to as liquid, is preferably understood to be drinking or domestic water or other fluid provided for heating in a domestic or commercial environment. The direction of the flow is dependent on how the heating cartridge or the fluid flow channel is configured and arranged, respectively, and in which position the continuous heater is to be installed when used as intended.

A preferred development of the utility model is characterized in that the coupling element comprises a thermally conductive metal, in particular brass. This ensures a fast heat transfer between the coupling element and the switching element. In addition, the corresponding durability and strength are ensured by the heat conductive metal. Preferably, the coupling element is constructed solid and integrally. Alternatively, the coupling element may be composed of other thermally conductive metals, in particular aluminum, copper, stainless steel (e.g. stainless steel with the technical name V2A or V4A), silver, gold or an alloy comprising at least one thermally conductive metal. A further preferred development of the utility model is characterized in that the coupling element is composed of a multicomponent material which comprises at least one thermally conductive metal.

A further advantageous embodiment of the utility model is characterized in that the hollow space of the coupling element is formed at least substantially cylindrically. This provides the advantage that the cavity can be produced by simple and cost-effective production techniques. Furthermore, the cylindrical cavity has a positive flow effect, since it is circulated continuously and without significant vortex formation. Thus, the coupling element has no negative influence on the flow resistance. Preferably, the cylindrical recess is produced by a drilling or milling process into the solid body. It is further preferred that the region of the cavity of the recess that is directed relative to the opening of the cavity and thus in the side facing away from the fluid is at least substantially of a part-spherical configuration. The flow behavior of the fluid in this region is thereby further improved, and a continuous exchange of the fluid in a partial region surrounding the coupling element takes place even at a possibly low flow rate of the fluid.

A preferred development of the utility model is characterized in that the hollow-forming recess of the coupling element is at least substantially square. The square cavity of the recess can positively influence the heat transfer properties between the coupling element and the switching element in a specific design of the fluid-conducting channel. The geometry of the recess is advantageous in that a reliable circumferential flushing of the recess is achieved by the fluid, depending on the design of the heating cartridge and the arrangement of the coupling element in the heating cartridge.

A further advantageous embodiment of the utility model is characterized in that the switching element is arranged on the coupling element on the side facing away from the fluid. The heat absorbed by the inner surface of the recess of the coupling element forming the cavity is thereby transferred to the switching element in as short a path as possible, so that a voltage-free switching of the circuit of the continuous heater is achieved to a certain extent without delay when a predetermined maximum temperature is reached. Furthermore, the side of the coupling element facing away from the fluid is not in direct contact with the fluid, whereby the switching element can be made of a more advantageous material, which does not have to be corrosion-resistant.

A further preferred embodiment of the utility model is characterized in that the coupling element arranged in the heating cartridge is arranged in particular in a force-locking and/or form-locking manner in the coupling element receptacle of the fluid-flow channel. This provides the advantage that the coupling element is reliably arranged in a pressure and impact resistant manner. Preferably, the arrangement of the coupling element in the coupling element receptacle is configured to be reversible, so that the STB according to the utility model is provided to be exchangeable.

A further advantageous embodiment of the utility model is characterized in that the recess forming the cavity in the coupling element extends in depth over at least half the size of the coupling element receptacle. In this way, it is ensured that the coupling element has a corresponding strength in terms of construction, so that the coupling element on the one hand remains in a fluid state under precompression and on the other hand has as little inherent thermal capacity as possible.

A further advantageous embodiment of the utility model is characterized in that the coupling element has an outer surface with at least one thread, a profiled surface and/or at least one circumferential sealing element receptacle. In this way, it is ensured that the coupling element is designed to be installed with low production effort and, if necessary, to be removed again in a non-destructive manner. By means of the sealing device receptacle, the coupling element is arranged in a sealing and airtight fit in the fluid-flowing channel.

A further advantageous embodiment of the utility model is characterized in that at least one sealing means, preferably in the form of an O-ring, is arranged on the outer face of the coupling element and/or the coupling element receptacle. This ensures a reliable seal between the coupling element and the switching element and thus reliably separates the fluid-conducting region from the voltage-conducting electrical region.

An advantageous development of the utility model is characterized in that the coupling element is arranged in the coupling element receptacle at the fluid contact side against the flow direction at least substantially perpendicularly to the wall of the fluid-conducting channel or obliquely to the wall of the fluid-conducting channel. In this way, even with different positioning of the coupling element in the fluid-conducting channel and with different flow rates and flow velocities in the fluid-conducting channel, a circumferential flushing of the cavity with fluid is always ensured. In general, the insertion is carried out at least substantially perpendicularly to the direction of extension of the fluid-conducting channel, wherein "at least substantially perpendicularly" in the sense of the present utility model means orthogonal or almost orthogonal, that is to say, at most ±10° from orthogonal.

A further preferred embodiment of the utility model is characterized in that the coupling element is arranged at least substantially flush with the inner surface of the fluid-conducting channel on the fluid contact side. This provides the advantage that no undesired vortex flow of the fluid occurs in the fluid-carrying channel when flowing through the coupling element. According to another preferred embodiment, the coupling element should form a non-convex surface with the inner face. By "at least substantially flush" is meant in the sense of the present utility model that it is either flush or almost flush with the inner face, i.e. flush with a deviation of a few millimeters.

A further suitable embodiment of the utility model is characterized in that the coupling element is arranged to protrude at least partially into the fluid-conducting channel on the fluid-contacting side. This achieves as complete an overall circumferential coupling element as possible. By extending the coupling element into the channel through which the fluid flows and thus directly into the fluid flow, a desired vortex of the fluid is generated in the region of the coupling element and in this way a local temperature difference of the fluid is compensated for by improved mixing. The exact positioning of the coupling element with respect to the depth of penetration can be optimally adapted to different flow situations for such exact positioning. By targeted generation of turbulence in the region of the coupling element, an optimal heat transfer is always achieved between the fluid and the coupling element.

According to a further preferred embodiment of the utility model, the coupling element is arranged to protrude at least partially into the fluid-conducting channel on the fluid-contacting side counter to the flow direction.

Another suitable embodiment of the utility model is characterized in that the wall of the recess forming the cavity has a minimum thickness of at least 1mm. In this way, a reliable and durable use can be achieved in the event of pressure and temperature fluctuations inside the heating cartridge. It is further preferred that the minimum thickness of the walls of the recess forming the cavity is in the range between 2 and 4 mm.

A further advantageous embodiment of the utility model is characterized in that the coupling element is made of a material suitable for drinking water.

Drawings

Further preferred and/or suitable features and embodiments of the utility model emerge from the dependent claims and the description. Particularly preferred embodiments are explained in detail with the aid of the figures.

Figure 1 shows a schematic view of a safety temperature limiter according to the utility model and a channel for fluid communication,

FIG. 2 shows a schematic view of the safety temperature limiter shown in FIG. 1 and inserted into a channel through which fluid flows, an

Fig. 3 shows a schematic view of the safety temperature limiter in a perspective view.

Detailed Description

The continuous heater according to the utility model, in particular the safety temperature limiter, is elucidated in detail with reference to the drawings.

A continuous heater according to the utility model (not shown in the figures) for heating a liquid is first described in detail below with the aid of fig. 1. The continuous heater comprises a heating cartridge 10 with at least one fluid-circulating channel 11, wherein at least one heating element of an electrical heater (not shown in the figures) is arranged in the fluid-circulating channel 11 for heating a liquid.

The continuous heater further comprises at least one safety temperature limiter 12, abbreviated as "STB", arranged to switch the at least one heating element to no voltage when a predetermined maximum temperature of the liquid is exceeded.

STB 12 comprises a coupling element 13 and a temperature controlled switching element 14. The coupling element 13 is constructed and arranged for transferring heat from the liquid to the switching element 14. The switching element 14 enables the actual switching process of the continuous heater without voltage switching or the switching off of the at least one heating element.

The coupling element 13 has a region facing away from the fluid and a region on the fluid contact side. The region facing away from the fluid is not in contact with the liquid, whereas the region of the fluid-contacting side of the coupling element 13 is at least partially in contact with the liquid. Furthermore, the switching element 14 is arranged in a region of the coupling element 13 facing away from the fluid. Furthermore, the coupling element 13 has a fluid contact side 15 on the fluid contact side, which is designed to be at least partially in contact with the liquid. Furthermore, the coupling element 13 has at least one recess 16 on the fluid contact side, which forms a cavity. In other words, the recess 16 forms a hollow space in the coupling element 13 that is filled with liquid.

Both the coupling element 13 and the hollow 16 forming the cavity are preferably cylindrically shaped, as can be seen, for example, from fig. 3. By means of the cylindrical design, the coupling element 13 can be inserted into the circular recess and thus be arranged in the fluid-conducting channel 11.

Such STB 12 is preferably arranged in the through-flow direction or flow direction of the liquid 30 in the last channel of the respective outlet side of the channels 11 through which the fluid flows. The continuous heater according to the utility model further comprises at least one coupling element receptacle 17 in the fluid flow channel 11. The coupling element receptacle 17 is arranged in the region of the fluid-conducting channel 11 and comprises a passage 18 through which the interior of the fluid-conducting channel 11 is accessible to the coupling element 13.

Preferably, the STB 12 according to the utility model is arranged on the fluid-conducting channel 11 by means of the coupling element receptacle 17, and at least the region of the fluid-contacting side of the STB 12 is hydraulically connected to the interior space of the fluid-conducting channel 11. The geometry and dimensions of the coupling element receptacle 17 are selected such that they correspond to the geometry and dimensions of the coupling element 13, and the coupling element 13 is arranged such that it can be arranged in the coupling element receptacle 17 through the aperture 18.

Furthermore, the coupling element 13 has an outer face 19. The outer surface 19 comprises, for example, a circumferential sealing element receptacle 20 and a profiled surface 21. The outer face 19 of the coupling element 13, which has a circumferential sealing element receptacle 20 and a profiled surface 21, is configured at least in sections tapering toward the coupling element receptacle 17.

Fig. 2 shows a schematic view of the STB 12 shown in fig. 1 and inserted into the channel 11 through which fluid flows. As can be seen in fig. 2, the STB 12 is arranged in the coupling element receptacle 17 of the fluid-flow channel 11. For this purpose, the STB 12 is arranged on the fluid contact side in a sealed manner with the coupling element 13 via a through-opening 18 in the coupling element receptacle 17. The sealing effect is achieved here, on the one hand, by the coupling element 13 being arranged in the coupling element receptacle 17 in a force-and/or form-locking manner. The tapering configuration of the outer surface 19 of the coupling element 13 in combination with the corresponding geometry of the coupling element receptacle 17 results in the coupling element 13 being provided for a closed-fitting arrangement in the coupling element receptacle 17.

On the other hand, the sealing action is effected in addition by at least one sealing means 22, which is arranged in the sealing means receptacle 20. The arrangement of the coupling element 13 in the coupling element receptacle 17 is preferably configured to be reversible. The sealing means 22 further preferably comprises a surrounding sealing means, such as an O-ring.

Preferably, the continuous heater according to the utility model comprises at least one clip (not shown in the figures) for supportingly securing the STB 12 in the coupling element housing 17. For this purpose, not only the coupling element 13 but also the coupling element receptacle 17 comprise corresponding clip receptacles 26. In the inserted state of the STB 12 into the coupling element receptacle 17, the clip receptacle 26 is constructed and arranged to receive at least one clip.

In fig. 2, the coupling element 13 with the fluid contact side 15 is arranged in the coupling element receptacle 17 in such a way that it does not influence or only does not significantly influence the flow direction 30 of the liquid in the fluid-flowing channel 11. In an alternative embodiment (not shown in the figures), the coupling element 13 with the fluid contact side 15 is arranged in the coupling element receptacle 17 such that it is oriented in the direction of the flow direction of the liquid 30. This causes the coupling element 13 to be oriented with the recess 16 forming the cavity against the flow direction 30 of the liquid and the liquid to flow into the cavity. In this way a particularly fast response characteristic of the STB according to the utility model is achieved.

According to a preferred further embodiment of the utility model, which is shown in fig. 2, the coupling element 13 is arranged on the fluid-contacting side in such a way that it terminates at least substantially flush with the inner face 23 of the fluid-conducting channel 11. In other words, the coupling element 13 is arranged such that it ends flush or substantially flush with the inner face 23 of the fluid-circulating channel 11 on the fluid contact side. By the at least substantially flush arrangement of the coupling elements 13, the liquid flow is disturbed as little as possible and the formation of turbulence in the region of the coupling elements 13 is reduced to a minimum. In order to influence the flow of liquid as little as possible without interference, an optimal heat transfer from the liquid to the coupling element 13 takes place simultaneously via the hollow-forming recess 16.

Furthermore, fig. 1 and 2 show the depth 24 of the cavity-forming recess 16 of the coupling element 13. The depth 24 of the recess 16 forming the cavity extends over at least half the size of the coupling element receptacle 17, wherein the size of the coupling element receptacle 17 is defined in particular by the smallest width of the through-opening 18 of the fluid-conducting channel 11. The coupling element 13 has a circumferential wall 25 which laterally encloses the cavity and has a defined wall width. The wall width of the wall 25 is preferably embodied to be at least 1mm wide. The smallest wall width of the wall 25 is located, for example, in the region of the sealing device receptacle 20, the clip receptacle 26 or in the region of the profiled surface 21.

Fig. 3 shows a schematic diagram of the STB 12 in perspective view. In particular, the coupling element 13 of the STB 12 is rotationally symmetrical with respect to the axis 21. In particular, the outer face 19, the sealing device receptacle 20 and the region of the profiled surface 21 of the coupling element 13 are thus likewise rotationally symmetrical. The cross-section of these elements is preferably circular in this case. The rotationally symmetrical construction of the coupling element 13 offers the advantage that the coupling element 13 can be manufactured in a cutting manner by turning.

Claims

1. A continuous heater for heating a liquid, the continuous heater comprising

A heating cartridge (10) having at least one channel (11), wherein the at least one channel (11) is a fluid-flowing channel (11), wherein at least one electrically heated heating element provided for heating the liquid is arranged in the fluid-flowing channel (11), and

at least one safety temperature limiter (12) which is provided for switching the at least one heating element to no voltage by means of a temperature-controlled switching element (14) when a predetermined maximum temperature of the liquid is exceeded,

wherein the safety temperature limiter (12) comprises a coupling element (13) configured for transferring heat from the liquid onto the switching element (14), the coupling element comprising a fluid contact side (15), wherein the coupling element (13) is arranged to be at least partially in contact with the liquid,

it is characterized in that the method comprises the steps of,

the coupling element (13) has at least one recess (16) on the fluid contact side, which recess forms a cavity.

2. Continuous heater according to claim 1, characterized in that the heating cartridge (10) comprises a plurality of channels (11) arranged in series, and the coupling element (13) is arranged behind the respective last one of the channels (11) with electrically heated heating elements with respect to the flow direction (30).

3. Continuous heater according to claim 1 or 2, characterized in that the coupling element (13) comprises a heat conducting metal.

4. Continuous heater according to claim 1 or 2, characterized in that the cavity-forming recess (16) of the coupling element (13) is at least essentially cylindrically configured.

5. Continuous heater according to claim 1 or 2, characterized in that the cavity-forming recess (16) of the coupling element (13) is at least substantially square in configuration.

6. Continuous heater according to claim 1 or 2, characterized in that the switching element (14) is arranged to rest against the coupling element (13) on the side facing away from the fluid.

7. Continuous heater according to claim 1 or 2, characterized in that a coupling element (13) arranged in the heating cartridge (10) is arranged in a coupling element receptacle (17) of the fluid-flowing channel (11).

8. Continuous heater according to claim 1 or 2, characterized in that the cavity-forming recess (16) in the coupling element (13) extends over at least half the size of the coupling element receptacle (17) over a depth (24).

9. Continuous heater according to claim 1 or 2, characterized in that the coupling element (13) has an outer face (19) with at least one thread, a profiled surface (21) and/or at least one surrounding sealing means receptacle (20).

10. Continuous heater according to claim 1 or 2, characterized in that at least one sealing means (22) is arranged on the outer face (19) of the coupling element (13) and/or the coupling element receptacle (17).

11. Continuous heater according to claim 7, characterized in that the coupling element (13) is arranged at least substantially perpendicularly to the wall of the fluid-flow channel (11) or obliquely against the flow direction (30) in the coupling element receptacle (17) on the fluid contact side.

12. Continuous heater according to claim 1 or 2, characterized in that the coupling element (13) is arranged on the fluid contact side to terminate at least substantially flush with an inner face (23) of the fluid-flowing channel (11).

13. Continuous heater according to claim 1 or 2, characterized in that the coupling element (13) is at least partly arranged on the fluid contact side to protrude into the fluid-circulating channel (11).

14. Continuous heater according to claim 1 or 2, characterized in that the minimum thickness of the walls (25) of the cavity-forming recess (16) is at least 1mm.

15. Continuous heater according to claim 1 or 2, characterized in that the coupling element (13) is composed of a material suitable for potable water.

16. A continuous heater according to claim 3, characterized in that the coupling element (13) is made of brass.

17. Continuous heater according to claim 7, characterized in that the coupling element (13) arranged in the heating cartridge (10) is arranged in a force-locking and/or form-locking manner in the coupling element receptacle (17) of the fluid-flow channel (11).

18. Continuous heater according to claim 10, characterized in that at least one sealing means (22) in the form of an O-ring is arranged on the outer face (19) of the coupling element (13) and/or the coupling element receptacle (17).