Hot water device, and hot water system comprising such a hot water device

Abstract

Hot water device, comprising: a tank, an outlet, and a distributor that comprises: a supply conduit and a distributor body that extends around the supply conduit so that a riser space is enclosed between an outer wall of the supply conduit and an inner wall of the distributor body; wherein the distributor body comprises a lower zone comprising one or more than one lower outflow opening, and a higher zone comprising one or more than one higher outflow opening; and wherein the one or more than one lower outflow opening is provided with a non-return valve that is configured to selectively allow the outflow of heated water from the distributor body to the tank. The invention further relates to a hot water system comprising such a hot water device.

Description

[0001] HOT WATER DEVICE, AND HOT WATER SYSTEM COMPRISING SUCH A HOT WATER DEVICE

[0002] The invention relates to a hot water device, and to a hot water system comprising such a hot water device.

[0003] More in particular, the invention relates to a hot water device, comprising a tank that is configured to store heated water in thermal layers, an outlet configured to extract heated water from a top layer at or near an upper side of the tank, and a distributor configured to supply heated water to the tank. Storing of a liquid in thermal layers is also known as thermal stratification.

[0004] Thermal stratification is the tendency of water to form layers of different temperatures in a storage tank due to differences in density caused by temperature variations. When water is heated, its density decreases and it becomes less dense than the cooler water below it. This causes it to rise to the top of the tank, forming a layer of hot water. At the same time, the cooler water from the bottom of the tank sinks to the bottom, forming a layer of cold water. The layers of water in the tank remain stratified because of the difference in density between the hot and cold water. The density difference creates a barrier to mixing, and the layers will remain separate as long as there is no external force that can cause them to mix, such as stirring or turbulence. This stratification can be maintained for a long time, as long as there is no external disturbance, and the temperature difference between the layers remains significant.

[0005] Dependent on the type of hot water device, it may be desirable to prevent mixing of the thermal layers. Such mixing may especially occur when heated water is introduced into the tank, or when water is withdrawn from the tank, as the flow in or out of the tank may cause a turbulence and disturbance of the thermal layers. It is therefore desired that the stratification is not disturbed, while at the same allowing water to be introduced into the tank and / or removed via the outlet.

[0006] United States patent application US 4 510 922 A, which is considered the closest prior art, is related to an energy storage system having thermally stratisfied liquid. Relative to this document, at least the features of the characterizing portion of claim 1 are novel. European patent application EP 3 594 600 A1 and an article published in the Chemie Ingenieur Technik 2008, 80, No. 3 by S. Gbppfert, XP055190647, ISSN: 0009-286X, are acknowledged as further prior art.

[0007] An objective of the present invention is to provide a hot water device, that is improved relative to the prior art and wherein at least one of the above stated problems is obviated or alleviated.

[0008] Said objective is achieved with the hot water device according to claim

[0009] 1 of the present invention, comprising:

[0010] - a tank that is configured to store heated water in thermal layers;

[0011] - an outlet configured to extract heated water from a top layer at or near an upper side of the tank; and

[0012] - a distributor configured to supply heated water to the tank, and comprising:

[0013] - a supply conduit and a distributor body, both of which extend in a height direction in the tank;

[0014] - wherein the distributor body comprises in a longitudinal direction thereof a lower zone comprising one or more than one lower outflow opening, and a higher zone comprising one or more than one higher outflow opening;

[0015] - wherein the distributor body extends around the supply conduit so that a riser space, in which heated water that exits the supply conduit at a lower side thereof may flow upwards, is enclosed between an outer wall of the supply conduit and an inner wall of the distributor body; and

[0016] - wherein the one or more than one lower outflow opening in the lower zone is provided with a non-return valve that is configured to selectively allow the outflow of heated water from the distributor body to the tank if the pressure difference between the heated water in the riser space and a layer of water in the tank at the level of the lower zone is below a predetermined threshold value.

[0017] Water is introduced into the tank via the distributor. The non-return valve in the one or more than one lower outflow opening in the lower zone of said distributor selectively allows the outflow of heated water to the tank at a thermal layer that matches the temperature of to be introduced heated water. This effect is achieved by the non-return valve that is configured to selectively allow the outflow of heated water if the pressure difference between the heated water in the riser space and a layer of water in the tank at the level of the lower zone is below a predetermined threshold value. If the heated water is hotter than the water stored in the tank at the level of the non-return valve, the density of this hotter water inside the distributor will be lower than the density of the cooler water in the tank. As a result, the non-return valve will remain closed, allowing the hotter water inside the distributor to rise in the riser space until it reaches a next outflow opening at a higher level. If this next outflow opening also comprises a non-return valve, the same principle will be effective again. If a nonreturn valve is absent in a next outflow opening, the heated water in the riser space will pass via said next outflow opening into the tank. In this way, the hot water device according to the invention is able to introduced heated water into a most appropriate thermal layer in the water tank, thereby reducing the risk of disturbing the thermal stratification in the tank.

[0018] The above mentioned objective is furthermore achieved with a hot water system, comprising:

[0019] - a hot water device according to claim 1 ;

[0020] - a heating circuit, comprising:

[0021] - a heat exchanger that is in fluid communication with a heat source through a primary medium; and

[0022] - a pump that is configured to withdraw water from a bottom side of the tank and direct it through the heat exchanger as a secondary medium; and

[0023] - wherein the heat exchanger is configured to heat the water that is withdrawn from the tank via the primary medium with heat from the heat source before returning this water via the distributor to the tank.

[0024] According to a preferred embodiment of the hot water system, the heat exchanger is in fluid communication with at least one further heat source. In this way, the water inside the tank of the hot water device may be heated with energy obtained from at least one of the heat source and the further heat source.

[0025] According to a further preferred embodiment of the hot water system, the heat source comprises a burner, and the at least one further heat source is a renewable energy source out of the group comprising: a solar collector, a heat pump and an electric heater connected to at least one solar panel. In this way, the water inside the tank of the hot water device may be heated with energy obtained from at least one of the heat source that comprises the burner, and the further renewable heat source. Thus, on the one hand, renewable energy may be used when it is available, for example energy generated by a solar energy system during a sunny day. On the other hand, if the energy provided by the renewable energy source is insufficient or not available at all, the heat source that comprises the burner may provide a back up.

[0026] According to an even further preferred embodiment of the hot water system, the at least one further heat source comprises at least a heat pump or other heating source that is configured to, in addition to being able to act as a further heat source for heating water from the tank, selectively extract heated water from the tank and provide it to a heat consumer, such as a heating system of a building. In this way, the hot water system may be used to store hot water for future use as an energy source. For example, a surplus of energy from a renewable energy source acting as the further heat source may be stored as heat in the tank, while said heat may be actively withdrawn from the tank at times when there is a shortage of energy from the renewable energy sources. In other words, the hot water system allows the hot water device to be used as a centralized energy buffer for renewable energy. Energy buffered as heat in the tank of the hot water device may be used for heating tap water, or for heating the water inside a central heating system.

[0027] Preferred embodiments are the subject of the dependent claims.

[0028] The various aspects and features described and shown in the specification can be applied, individually, wherever possible. These individual aspects, and in particular the aspects and features described in the attached dependent claims, may be an invention in its own right that is related to a different problem relative to the prior art.

[0029] In the following description preferred embodiments of the present invention are further elucidated with reference to the drawing, in which:

[0030] Figure 1 is a schematic view of a hot water device according to a first preferred embodiment of the invention;

[0031] Figure 2 is a detailed schematic view of a distributor of the hot water device of Figure 1 in a distributing state wherein it selectively distributes heated water in a dedicated thermal layer;

[0032] Figure 3 is a detailed schematic view of the distributor of the hot water device of Figure 1 in a bypassing state wherein it bypasses heated water that is at a too low temperature; Figure 4 is a schematic view of a hot water system according to a first preferred embodiment; and

[0033] Figure 5 is a schematic view of a hot water system according to a second preferred embodiment.

[0034] The hot water device 1 shown in Figure 1 comprises a tank 2, an outlet 3 and a distributor 4. The tank 2 is configured to store heated water in thermal layers 5, for illustrative reasons schematically indicated in Figure 1 as a lower layer 5-L that is a relatively cold layer, a thermal layer comprising water at an intermediate temperature 5-I, and a relatively hot thermal layer 5-H that defines a top layer 5-T. In practice, more than three thermal layers may be present in tank 2. The outlet 3 is configured to extract heated water from the top layer 5-T at or near an upper side 6 of the tank 2. Distributor 4 preferably extends into at least an upper third of the tank 2.

[0035] The distributor 4 is configured to supply heated water to the tank 2, and comprises a supply conduit 7 and a distributor body 8, both of which extend in a height direction h in the tank 2, wherein the distributor body 8 extends around the supply conduit 7 so that a riser space 9, in which heated water that exits the supply conduit 7 at a lower side 10 thereof may flow upwards (indicated with arrow II in Figure 2), is enclosed between an outer wall 11 of the supply conduit 7 and an inner wall 12 of the distributor body 8. Because the distributor body 8 extends around the supply conduit 7, the riser space 9 provides an insulation between the water inside the tank 2 and the heated water in the supply conduit 4.

[0036] The distributor body 8 comprises in a longitudinal direction thereof a lower zone Z-L comprising one or more than one lower outflow opening 13-L, and a higher zone Z-H comprising one or more than one higher outflow opening 13-H. The one or more than one lower outflow opening 13-L in the lower zone Z-L is provided with a non-return valve 14, 14-L that is configured to selectively allow the outflow of heated water from the distributor body 8 to the tank 2 if the pressure difference between the heated water in the riser space 9 and a layer of water in the tank 2 at the level of the lower zone Z-L is below a predetermined threshold value. In Figure 2, the heated water supplied via supply conduit 7 is at a temperature that substantially matches the temperature in top layer 5-T. Consequently, this heated water rises in riser space 9 until the temperature difference, at thus the difference in density, of the water inside the riser space 9 and the water at the respective thermal layer 5 in the tank substantially matches. In Figure 2, two higher outflow openings 13-H are shown. The lower one thereof is already partially open, and (although not shown) some leaking of heated water into the tank 2 may already occur here. However, the upper one of the higher outflow openings 13-H is fully opened to allow the heated water to flow from the riser space 9, via the upper higher outflow opening 13-H, into the hot thermal layer 5-H that defines a top layer 5-T.

[0037] As indicated in Figures 2 and 3, hot water device 1 may further comprise one or more than one intermediate zone Z-l with at least one intermediate outflow opening 13-1. This intermediate zone Z-l is provided between the lower zone Z-L and the higher zone Z-H. In the shown embodiment, the at least one intermediate outflow opening 13-1 in the one or more than one intermediate zone Z-l is provided with a nonreturn valve 14, 14-1 that is configured to selectively allow the outflow of heated water from the distributor body 8 to the tank 2 if the pressure difference between the heated water in the riser space 9 and a layer of water in the tank 2 at the level of the respective intermediate zone Z-l is below a predetermined threshold value.

[0038] As shown in Figures 2 and 3, the distributor 4 comprises a discharge opening 17 provided at a underside of the distributor 4. This discharge opening 17 is configured to discharge relatively cold water to a water layer of the tank 2 located below the distributor 4. Such a discharge is indicated by arrow D in Figure 3. Discharge opening 17 comprises a further non-return valve 18 configured to prevent a flow of water from the tank 2 through the discharge opening 17 to the riser space 9 if an upward flow of heated water in the riser space 9 inside the distributor 4 causes an underpressure near the discharge opening 17 of the distributor 4. In Figure 2, that shows a state with such an upward flow II in the riser space 9, the further non-return valve 18 closes off the discharge opening 17 by resting against the underside 19 of the distributor 4.

[0039] In the one or more than one higher zone Z-H, a non-return valve 14, 14- H may be arranged in the one or more than one higher outflow opening 13-H. This non-return valve 14-H prevents a flow of heated water from the tank 2 into the riser space 9 if the flow of relatively cold water through the discharge opening 17 of the distributor 4 creates an underpressure in the riser space 9. This situation is shown in Figure 3, wherein cold water is discharged via the flow D through the discharge opening 17. In this discharge state, the non-return valves 14, 14-L, 14-1, 14-H that are provided in outflow openings 13, 13-L, 13-1, 13-H of the riser space 9 rest against the outer wall 16 of the distributor body 8 of distributor 4, and consequently prevent that water may flow from the tank 2 into the riser space 9.

[0040] The non-return valve 14, 14-L in the lower zone Z-L, the non-return valve 14, 14-1 in the intermediate zone Z-l, and the non-return valve 14, 14-H in the higher zone Z-H may be of the same type. This also applies to the further non-return valve 18 at the discharge opening 17. Preferably, these non-return valves 14, 14-L, 14-1, 14- H and 18 comprise a membrane 15 that in a closed state, rests against an outer wall 16 of the distributor body 8 or, for the further non-return valve 18, rests against the underside 19 of the distributor body 8. Such a membrane is simple and reliable, and doesn’t require any maintenance. Periodic replacement is also easy. A typical predetermined threshold value for the pressure difference at which the membrane opens is in the range of 1 - 10 Pa, which allows for an effective control of the introduction of heated water in an appropriate thermal layer that matches the temperature of the heated water in the riser space 9 of the distributor 4. Due to a temperature difference between heated water in the riser space 9 and the thermal layers 5 in the tank, and the resulting difference in density, the membrane 15 may be pushed against the outer wall 16 of the distributor body 8 at pressures in the range of 10 -100 Pa. If the non-return valve 18 comprises a membrane 15, it provides a simple and reliable non-return valve 18 that is capable of opening at relatively small pressure differences in the range of 1 - 10 Pa on the one hand, whereas it is able to repeatedly withstand closing off pressures up to 100 Pa.

[0041] As a result of the non-return valves 14, the riser space 9 may be designed for a relatively high capacity and flow rates. More in particular, the riser space 9 may be designed for a Reynolds number Re > 500, preferably Re > 750, and more preferably Re > 1000.

[0042] In the shown preferred embodiment, the lower zone Z-L comprises a plurality of lower outflow openings 13-L and / or the higher zone Z-H comprises a plurality of higher outflow openings 13-H and / or the one or more than one intermediate zone Z-l comprises a plurality of intermediate outflow openings 13-1. Additional intermediate zones Z-l and / or a plurality of outflow openings 13 per zone allows the hot water device 1 to accurately introduce heated water in an appropriate thermal layer, thereby reducing the risk of turbulence and disturbance of the thermal layers in tank 2. If multiple outflow openings 13 are used, non-return valves 14 may be relatively small. Moreover, in case of malfunction of one of the non-return valves 14, this hardly influences the overall performance in case a relatively large number of relatively small non-return valves 14 are applied.

[0043] Preferably, at least one of the plurality of lower outflow openings 13-L, the plurality of higher outflow openings 13-H, and the plurality of intermediate outflow openings 13-1, comprises at least two outflow openings 13 that are distributed along a circumference defined by the outer wall 16 of the distributor body 8. In this way, the heated water flows in different positions and directions into a respective thermal layer 5 of water in the tank 2, thereby minimizing the risk of turbulence and disturbance of the thermal layers 5. More in particular, at least two outflow openings 13 that are distributed along a circumference defined by the outer wall 16 of the distributor body 8 are arranged at substantially the same height in the tank 2. Ideally, the at least two outflow openings 13 that are distributed around the circumference are substantially evenly distributed. Thus, if there are two outflow openings, they are arranged opposite to each other, but if there are three outflow opening distributed around the circumference, they are preferably arranged at 120° relative to each other.

[0044] Preferably at least one of the plurality of lower outflow openings 13-L, the plurality of higher outflow openings 13-H, and the plurality of intermediate outflow openings 13-1, have a minimum opening of 40 mm2. More preferably, at least one of the plurality of lower outflow openings 13-L, the plurality of higher outflow openings 13-H, and the plurality of intermediate outflow openings 13-1, have a maximum opening of 8000 mm2.

[0045] In height direction, adjacent outflow openings 13 are preferably arranged at an offset of at least 30 mm relative to each other. This minimum offset promotes a distinction between the thermal layers 5, and more in particular that a sufficient pressure difference between outflow openings 13 that are adjacent in height direction may build up to open the non-return valves 14.

[0046] As is schematically shown in Figures 1 ,4 and 5, the hot water device 1 preferably comprises a heating element 20 that is arranged in the distributor 4. Please note that, for reasons of simplicity, heating element 20 is not shown in Figures 2 and 3. Using heating element 20, a surplus of electrical energy from e.g. a solar energy system 21 may be used to heat the water inside the distributor 4. Although a solar energy system 21 may be also used as a further heat source 22 in another way that will be explained here below with reference to the hot water system 23 in Figures 4 and 5, the specific arrangement of a heating element 20 in the distributor 4 allows that a surplus of electrical energy may be effectively used for heating the water inside the distributor 4. Thus, the hot water device 1 allows surplus energy from durable energy sources to be used effectively, and decentralized, i.e. locally inside one’s own house or office.

[0047] The heating element 20 preferably comprises an electric heating element with an adjustable power. In this way, the heating element 20 in the distributor 4 also allows that a relatively small surplus of electrical energy may be used for heating the water inside the distributor 4.

[0048] Figures 4 and 5 show two embodiments of a hot water system 23 that comprises a hot water device 1 that is arranged in a heating circuit 24. The heating circuit 24 comprises a heat exchanger 25 that is in fluid communication with a heat source 26 through a primary medium, and a pump 27 that is configured to withdraw water from a bottom side 28 of the tank 2 and direct it through the heat exchanger 25 as a secondary medium. The heat exchanger 25 is configured to heat the water that is withdrawn from the tank 2 with heat from the heat source 26 via the primary medium, before returning this water via the distributor 4 to the tank 2.

[0049] The hot water system 23 preferably comprises at least one further heat source 29. In Figures 4 and 5, three further heat sources 29 are shown. More in particular, the heat source 26 may comprise a (not shown) burner, for example a gas burner. The at least one further heat source 29 is preferably a renewable energy source out of the group comprising: a solar collector 30, a heat pump 31 and an electric heater connected to at least one solar panel. It is noted that the solar collector 30 and the previously mentioned solar energy system 21 are schematically indicated at the same position in Figures 4 and 5. The solar energy system 21 in these Figures comprises the electric heater, that in itself is not visible in the schematic drawing. In order to prevent confusion, it is however explicitly mentioned that the electric heater of solar energy system 21 is used for heating up the primary medium that passes the heat exchanger 25, and consequently this electric heater is not the same as heating element 20. Figure 5 shows a second preferred embodiment of a hot water system 23. Both embodiments of Figures 4 and 5 largely correspond to each other, and for reasons of conciseness, mainly the differences will be described. Similar parts of both embodiments are indicated by the same reference numeral.

[0050] In the hot water system 23 according to the second preferred embodiment, the at least one further heat source 29 comprises at least a heat pump 31 or other heating source that is configured to, in addition to being able to act as a further heat source 29 for heating water from the tank 2, selectively extract heated water from the tank 2 and provide it to a heat consumer, such as a heating system 32 of a building. In this way, a surplus of energy from a renewable energy source acting as the further heat source 29 may be stored as heat in the tank 2, while said heat may be actively withdrawn from the tank 2 at times when there is a shortage of energy from the renewable energy sources. In other words, the hot water system 23 according to the second preferred embodiments allows the hot water device 1 to be used as a centralized energy buffer for renewable energy.

[0051] In Figure 5, tank 2 comprises a further conduit 33 connected to the outlet 3 at the top side 6 of the tank 2. Alternatively, further conduit 33 may be connected to a (not shown) further outlet. Using pump 27, hot water is withdrawn from a top layer 5-T. In the heating circuit 24, the hot water flows via a valve system 34 towards the heat exchanger 25. Valve system 34 preferably comprises a three-way valve 35. In heat exchanger 25, heat from the hot water that is withdrawn from the tank 2 of the hot water device 1 is transferred to the medium inside a further heating circuit 36. This heated medium, that is preferably also water, may flow via the heating system 32 to heat the building.

[0052] Heat exchanger 25 preferably comprises a plate heat exchanger. If the pump 27 comprises a pump with an adjustable pump flow, it is possible to adjust the flow rate and thereby adjust the residence time of the water inside the heat exchanger 25. For example, lowering the flow rate will increase the time required for the water to flow through the (plate) heat exchanger 25.

[0053] Hot water system 23 further comprise a controller 37 that is configured to adjust the pump flow of the pump 27 in dependence on a water temperature of the heated water stored in or extracted from the top layer 5-T of the tank 2. The temperature of the water in the tank 2 may be measured with a temperature sensor 38. The pump flow of the pump 27 is preferably reduced if the water temperature in the tank, measured by temperature sensor 38, drops below a predetermined threshold. In this way, a “boost mode” for fast heating of the water inside tank 2 is obtained. After all, due to the longer residence time of the water inside the heat exchanger 25, the water will be heated to a higher temperature. This however comes at the cost of a slightly lower efficiency. Consequently, the boost mod is preferably only used if there is a higher demand for hot water than already stored inside the tank 2 of the hot water device 1.

[0054] It is remarked that the heated water in tank 2 may be tap water, than can be used for consumption, showering, etc. It is however also conceivable that - in an alternative hot water system 23 - the water in tank 2 is part of a closed circuit and not intended for domestic use. Instead, heat stored in the water inside tank 2 may be used to heat tap water in a separate heating circuit via heat exchanger 25.

[0055] Although they show preferred embodiments of the invention, the above described embodiments are intended only to illustrate the invention and not to limit in any way the scope of the invention. Accordingly, it should be understood that where features mentioned in the appended claims are followed by reference signs, such signs are included solely for the purpose of enhancing the intelligibility of the claims and are in no way limiting on the scope of the claims. Furthermore, it is particularly noted that the skilled person can combine technical measures of the different embodiments. The scope of protection is defined solely by the following claims.

Claims

CLAIMS1. Hot water device, comprising:- a tank that is configured to store heated water in thermal layers;- an outlet configured to extract heated water from a top layer at or near an upper side of the tank; and- a distributor configured to supply heated water to the tank, and comprising:- a supply conduit and a distributor body, both of which extend in a height direction in the tank; and- wherein the distributor body comprises in a longitudinal direction thereof a lower zone comprising one or more than one lower outflow opening, and a higher zone comprising one or more than one higher outflow opening; and characterized in that:- the distributor body extends around the supply conduit so that a riser space, in which heated water that exits the supply conduit at a lower side thereof may flow upwards, is enclosed between an outer wall of the supply conduit and an inner wall of the distributor body; and- the one or more than one lower outflow opening in the lower zone is provided with a non-return valve that is configured to selectively allow the outflow of heated water from the distributor body to the tank if the pressure difference between the heated water in the riser space and a layer of water in the tank at the level of the lower zone is below a predetermined threshold value.

2. Hot water device according to claim 1 , wherein:- one or more than one intermediate zone with at least one intermediate outflow opening is provided between the lower zone and the higher zone; and- wherein the at least one intermediate outflow opening in the one or more than one intermediate zone is provided with a non-return valve that is configured to selectively allow the outflow of heated water from the distributor body to the tank if the pressure difference between the heated water in the riser space and a layer of water in the tank at the level of the respective intermediate zone is below a predetermined threshold value.

3. Hot water device according to claim 1 or 2, wherein the non-return valve comprises a membrane that, in a closed state, rests against an outer wall of the distributor body.

4. Hot water device according to one or more than one of the foregoing claims, wherein the distributor comprises:- a discharge opening provided on a underside of the distributor and configured to discharge relatively cold water to a water layer of the tank located below the distributor; and- a further non-return valve configured to prevent a flow of water from the tank through the discharge opening to the riser space if an upward flow of heated water in the riser space inside the distributor causes an underpressure near the discharge opening of the distributor.

5. Hot water device according to one or more than one of the foregoing claims, wherein the non-return valve in the one or more than one higher outflow opening in the one or more than one higher zone is arranged to prevent a flow of heated water from the tank into the riser space if a flow of relatively cold water through the discharge opening of the distributor creates an underpressure in the riser space.

6. Hot water device according to claim 4 or 5, wherein the non-return valve and / or the further non-return valve comprises a membrane arranged against an outer wall of the distributor.

7. Hot water device according to one or more than one of the foregoing claims, wherein the distributor extends into at least an upper third of the tank.

8. Hot water device according to one or more than one of the foregoing claims, wherein at least one of:- the lower zone comprises a plurality of lower outflow openings; and- the higher zone comprises a plurality of higher outflow openings.

9. Hot water device according to one or more than one of the foregoing claims 2-8, in dependence of at least claim 2, wherein the one or more than one intermediate zone comprises a plurality of intermediate outflow openings.

10. Hot water device according to claim 8 or 9, wherein at least one of the plurality of lower outflow openings, the plurality of higher outflow openings, and the plurality of intermediate outflow openings, comprises at least two outflow openings that are distributed along a circumference defined by the outer wall of the distributor body.

11. Hot water device according to claim 10, wherein the at least two outflow openings that are distributed along a circumference defined by the outer wall of the distributor body are arranged at substantially the same height in the tank.

12. Hot water device according to one or more than one of claims 8-11 , wherein at least one of the plurality of lower outflow openings, the plurality of higher outflow openings, and the plurality of intermediate outflow openings, have a minimum opening of 40 mm2.

13. Hot water device according to one or more than one of the foregoing claims 8-12, wherein at least one of the plurality of lower outflow openings, the plurality of higher outflow openings, and the plurality of intermediate outflow openings, have a maximum opening of 8000 mm2.

14. Hot water device according to one or more than one of the foregoing claims, wherein in height direction adjacent outflow openings are arranged at an offset of at least 30 mm relative to each other.

15. Hot water device according to one or more than one of the foregoing claims, wherein a heating element is arranged in the distributor.

16. Hot water device according to claim 15, wherein the heating element comprises an electric heating element with an adjustable power.

17. Hot water system, comprising:- a hot water device according to one or more than one of the foregoing claims;- a heating circuit, comprising:- a heat exchanger that is in fluid communication with a heat source through a primary medium; and- a pump that is configured to withdraw water from a bottom side of the tank and direct it through the heat exchanger as a secondary medium; and- wherein the heat exchanger is configured to heat the water that is withdrawn from the tank with heat from the heat source via the primary medium before returning this water via the distributor to the tank.

18. Hot water system according to claim 17, wherein the heat exchanger is in fluid communication with at least one further heat source.

19. Hot water system according to claim 17 or 18, wherein:- the heat source comprises a burner; and- the at least one further heat source is a renewable energy source out of the group comprising: a solar collector, a heat pump and an electric heater connected to at least one solar panel.

20. Hot water system according to claim 19, wherein the at least one further heat source comprises at least a heat pump or other heating source that is configured to, in addition to being able to act as a further heat source for heating water from the tank, selectively extract heated water from the tank and provide it to a heat consumer, such as a heating system of a building.

21. Hot water system according to one or more than one of the claims 17-20, wherein the heat exchanger comprises a plate heat exchanger.

22. Hot water system according to one or more than one of the claims 17-21 , wherein the pump comprises a pump with an adjustable pump flow.

23. Hot water system according to claim 22, comprising a controller that is configured to adjust the pump flow of the pump in dependence on a water temperature of the heated water stored in or extracted from the top layer of the tank.

24. Hot water system according to claim 23, comprising the step of reducing the pump flow of the pump if the water temperature drops below a predetermined threshold.

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