HOT WATER SYSTEM

Description

The invention relates to a hot water system.

A hot water system includes a drinking water heater with hot water storage tank and one or more tapping stations to which hot water flows from the drinking water heater through a line system.

Long line paths mean that the provision of hot water from the drinking water heater to the tapping stations takes a considerable amount of time. If no water is tapped, the water stands in the line system and cools down. Water that has stood in the line system for a longer period of time can lead to a hygiene problem if water bacteria, such as legionella, multiply rapidly.

In conventional line systems with long line paths, for reasons of convenience a circulation line is provided that ensures that hot water circulates in the line system and thus always flows past or close to the tapping stations, so that hot water is available at the tapping stations immediately or after a short time. If the temperature of the circulating hot water is sufficiently high, water bacteria will be killed, thus reducing hygiene problems. However, circulation requires a pump, which consumes as much energy as heating the circulating hot water. Heating the constantly circulating drinking water to approximately 60 degrees Celsius, with possibly only a short tapping time during which water is drawn, is complex and involves thermal losses and electrical expenditure. In addition, in a system with a heat pump for heating, the greatest heat pump-related losses occur at approximately 60 degrees Celsius. The circulating drinking water also leads to the mixing of the drinking water stored in the hot water reservoir, which has a negative effect on the performance of the heat pump. These effects result in a loss of approximately 50% of the energy used.

If the volume in the lines between the drinking water heater and at least one of the tapping stations is greater than 3 liters, a circulation line or temperature control bands are mandatory for hygiene reasons in accordance with legal requirements in Germany.

According to the German Drinking Water Ordinance, a distinction is made between small and large systems. In small systems, the volume in the line paths between the drinking water heater and the tapping points is less than or equal to 3 liters. In addition, the capacity of the hot water reservoir of the drinking water heater is less than or equal to 400 liters. If these requirements are not met, it is a large-scale system, unless the hot water system is in a single-or two-family house. For large systems in public or commercial buildings, including rental apartments, an annual microbiological drinking water test must be carried out. This obligation to examine does not apply to small systems.

CH 100 898 A shows a hot water supply system in which insulated hot water reservoirs are provided between the water heater and the tapping stations.

DE 41 39 288 A1 shows a hot water supply in which a continuous flow heater is provided between the water heater and the tapping stations, which serves for disinfection and heating.

DE 10 2011 122 639 A1 shows a hot water supply in which a continuous flow heater between the water heater and the tapping stations is controlled in such a way that it does not reheat the water when water is drawn from a household appliance, but reheats it when water is drawn manually.

AT 374 269 B shows a hot water supply in which a distributor is provided between the water heater and the tapping stations. If the temperature falls below a minimum, the water is passed through a branch of the pipe where it is heated.

DE 10 2014 225 693 A1 shows a hot water supply in which a distributor is provided between the water heater and the tapping stations. A parallel second line with an additional heat source can provide additional hot water if needed.

DE 295 03 746 U1 shows a hot water generator that stores latent heat.

The task is to provide an improved hot water system.

The object is achieved by a hot water system having the features of claim 1.

The hot water system is provided with a drinking water heater with a hot water reservoir, a tapping station, a circulation line-free line system between the drinking water heater and the tapping station, which is designed so that the heated drinking water flows from the drinking water heater along a line path in the line system to the tapping station. A pressure in the line system and a pipe cross-section of the line system depend on a length of the line path such that a line volume of the line path is less than or equal to a given maximum line volume. The line path comprises a first portion and a second portion, and a hot water station is provided between the first portion and the second portion and is designed to heat and/or store the drinking water.

Storage is particularly provided for heated drinking water, whether from the drinking water heater or heated by the hot water station.

The hot water system is circulation line-free; this means that there is no circulation line in which hot water constantly flows in a circle. This saves energy. In a system with a heat pump, approximately 50% energy is saved compared to a system with a circulation line due to the lack of circulation, as the effort for heating and circulating the drinking water is eliminated. In addition, the heat pump can be operated more efficiently due to the lack of mixing in the hot water reservoir. Advantageously, there is no fresh water station in the line system that uses heat from a water-based central heating system for instantaneous water heating, so the effort is low compared to a conventional hot water system.

The drinking water heater heats drinking water provided on the inlet side and stores this heated drinking water as hot water in the hot water reservoir. The hot water typically has a temperature in the range of 45 to 60 degrees Celsius, especially 50 to 60 degrees Celsius, and can be drawn off at the tap. Several tapping stations can be provided in the hot water system. Examples of tapping points are taps and showers.

The line volume of the line path is the volume of the lines in the line system along which the water flows from the drinking water heater to the tapping station.

The dimensioning of pressure and pipe cross-section, especially the inner pipe diameter, depends on the length of the line path and the specified maximum line volume between the drinking water heater and the tapping station. The maximum line volume is low for hygienic reasons. Advantageously, the maximum line volume is in accordance with legal or structural specifications. A small system within the meaning of the German Drinking Water Ordinance, in particular DVGW Worksheet W 551, has a maximum line volume of 3 liters, so that the mandatory annual microbiological drinking water testing is not required for such a system.

In comparison to a conventional hot water system, in which the line length of pipes with a given pipe cross-section is limited by the given maximum line volume, in the hot water system according to the invention both the pipe cross-section and the pressure are adjusted in order to achieve the desired line length despite the given maximum line volume. When adjusting the pipe cross-section, the inner pipe diameter is adjusted. The greater the desired line length, the higher the pressure and the smaller the pipe cross-section, i.e., the inner pipe diameter. The higher pressure also means a higher flow rate, so there is less deposit in the pipes and bacterial growth is inhibited. The length of the line path between the drinking water heater and the tapping station is longer than in conventional hot water systems without a circulation line. The length of the line path is advantageously longer than 25 m, in particular longer than 35 m, in particular longer than 45 m and in particular longer than 65 m.

Between the first portion and the second portion, a hot water station is provided in the line system and the drinking water flows through said hot water station. The hot water station is designed to heat and/or store hot water provided on the inlet side. If the previously heated drinking water has been standing in the line path for a long time because no hot water has been drawn off, the water, which has since cooled down, can be reheated by the hot water station before it is drawn off. Additionally or alternatively, hot water can be temporarily stored in the hot water station and drawn from there. This hot water may have flowed from the hot water reservoir in the hot water station or may have been heated in the hot water station. The hot water heated by the hot water station can have the same temperature range as the hot water provided by the hot water reservoir; advantageously, however, the hot water station heats the water to a higher temperature, for example 60 degrees Celsius. Preheating and/or intermediate storage by the hot water station improves comfort, as hot water is available at the tapping point more quickly than if no hot water station were provided and the cold water had to drain away in the lines first. The hot water station is a hot water transfer point between a supply line from the drinking water heater and the individual piping to the tapping points, which is formed by distribution lines between the hot water station and the tapping points. The first portion of the line path is the supply line. The second portion is the distribution line between the hot water station and the tapping point. The hot water station has connections for the distribution line and thus supplies a hot water branch. In a small residential unit, a hot water branch is usually provided for the kitchen and bathroom. In a larger residential unit, two hot water branches are often provided, one for the kitchen and one for the bathroom.

The optimization of pressure and pipe cross-section can concentrate on one of the portions. When concentrating on the first portion, i.e., the supply line to the hot water station, the maximum line volume is split into a first maximum volume for the first portion and a second maximum volume for the second portion. A first pressure in the first portion and a first pipe cross-section of the first portion depend on a length of the first portion, so that the line volume of the first portion is less than or equal to the first maximum volume. Then it is also necessary that the line volume of the second portion is less than or equal to the second maximum volume. This requirement must be met for the distribution line of the second portion.

Advantageously, the first pressure differs from a second pressure of the second portion. In order to cover a long distance with the supply line, the hot water flows through it at high pressure. This pressure is reduced in the hot water station. In one embodiment, a pressure booster is installed upstream of the drinking water heater in order to achieve high pressure in the first portion. To reduce the pressure, a pressure regulator is provided in the hot water station or the pressure regulator is installed upstream of the hot water station.

In one embodiment, one or more additional tapping stations are connected to the hot water station, wherein the line volumes in each line path between the drinking water heater and the additional tapping station or one of the additional tapping stations are less than or equal to the specified maximum line volume. Thus, for the line route to each tapping station, the line volume is less than or equal to the maximum line volume. Usually, the line path to the tapping station furthest away from the drinking water heater has the largest line volume, so as a rule of thumb when dimensioning it is sufficient that this line volume is less than or equal to the maximum line volume. Between the most distant tapping station and the drinking water heater, further tapping stations can be provided, which are advantageously connected to each other by a loop-through installation.

The following are examples of inner pipe diameters and pressures for specified maximum line lengths. For example, in the hot water system the inner pipe diameter can be less than or equal to 11.6 mm. Advantageously, the pressure is then greater than or equal to 0.71 bar. This allows a line length of 25 m to the hot water station to be achieved. For example, the inner tube diameter can be less than or equal to 9.6 mm. Advantageously, the pressure is then greater than or equal to 2.47 bar. This allows a line length of 35 m to the hot water station to be achieved. For example, the inner tube diameter can be less than or equal to 8.4 mm. Advantageously, the pressure is then greater than or equal to 6.01 bar. This allows a line length of 45 m to the hot water station to be achieved. For example, the inner tube diameter can be less than or equal to 7 mm. Advantageously, the pressure is then greater than or equal to 20.81 bar. This allows a line length of 65 m to the hot water station to be achieved. This maximum line length significantly exceeds the line path in a conventional hot water system without a circulation line. In the examples mentioned above, the pipes can have an outer diameter of 16 mm to facilitate assembly and installation by ensuring uniform pipe outer dimensions.

In one embodiment, the hot water station comprises a continuous flow heater which is designed to heat water during a discharge time until hot water from the drinking water heater has arrived at the hot water station. This increases comfort in long supply lines, as hot water is immediately available at the tapping point, even if the water in the line is already cold when it is drawn.

In one embodiment, the hot water station includes a bypass valve that bridges the instantaneous water heater as soon as hot water with a specified temperature is available on the inlet side of the hot water station. Hot water with a specified minimum temperature bypasses the instantaneous water heater. Nevertheless, the hot water station can be provided with an additional heater that additionally heats the hot water from the drinking water heater.

In one embodiment, the hot water station includes a small hot water reservoir of which the storage capacity is lower than that of the hot water reservoir of the drinking water heater. In this embodiment, the hot water station acts as a decentralized buffer, providing hot water closer to the tapping stations and thus shortening the time until hot water is available at the tapping stations.

Advantageously, the small hot water reservoir has thermal insulation, for example made of insulating material, so that heat loss to the environment is reduced and the cooling of the hot drinking water is delayed. Additionally or alternatively, the small hot water reservoir is designed to heat water stored therein. This makes it possible to reheat the cooled water during a longer downtime in which no water has been drawn from the small hot water reservoir and hot water has flowed in from the drinking water heater. Alternatively, the stored water can be heated when it cools below a predefined threshold to counteract the cooling, so that hot water is always available in the small hot water reservoir for use. Heating at a predetermined time, for example in the morning, ensures that hot water is available when it is typically needed.

Additionally or alternatively, the small hot water reservoir has a heat exchanger. The heat exchanger contains a phase change material, abbreviated as “PCM.” The drinking water flows in the primary circuit of the heat exchanger. The secondary circuit contains the phase change material, which stores a large part of the thermal energy supplied to it from the primary circuit in the form of latent heat (for example during a phase change from solid to liquid). Flowing and/or stored hot water, which may have been heated in the hot water station, causes a phase change of the phase change material so that the phase change material stores part of the thermal energy of the hot water. Nevertheless, there is sufficient hot water available at the tapping station, especially when hot water is flowing through. The phase change material can for example be wax-like and liquefy when heat is applied. If there has been no tapping for a long time, the latent heat stored in the phase change material serves to heat the cooling water to counteract the cooling. The phase change material solidifies again and discharges into the stored water the thermal energy released during this. Electrical heating can support the provision of hot water by reheating the stored water as it cools down below a predefined threshold, possibly also multiple times, in order to counteract the cooling, so that hot water is always available in the small water reservoir for use. The energy required for this is significantly lower than if no phase change material were provided.

In one embodiment, the heat exchanger of the small hot water reservoir has two separate drinking water primary circuits and a secondary circuit comprising the phase change material. This design of the hot water station combines the functionality of two hot water stations, as it provides drinking water for two hot water branches, for example for the bathroom and for the kitchen of an apartment. The lines of the two branches are separated from each other. There is no water exchange. However, thermal coupling occurs through the secondary circuit, because thermal energy from each of the primary circuits can be stored in the phase change material and released from the phase change material into each primary circuit. In other words, there is a heat exchange from each of the two primary circuits, which are separated from each other, with the secondary circuit, without any water exchange between the two primary circuits. More than two primary circuits can also be provided, which are thermally coupled in this way.

For example, a long shower with hot water in one hot water branch tapped can cause thermal energy to be stored, which is then released for water tapped in the kitchen in the other hot water branch. This design offers an additional increase in efficiency, because when hot water is drawn from one of the primary circuits, the phase change material acting as a storage device is thermally charged, and this charged energy store is also available to the other primary circuit.

The water reservoir can also be bypassed by a bypass valve if sufficient hot water has already been stored. However, the regular flow of hot water also advantageously results in regular charging of the phase change material that acts as a store.

In one version, the drinking water heater is coupled to a heat pump so that the heat pump heats drinking cold water to hot water. The circulation line-free line system leads to a high efficiency of the hot water system, since the efficiency of the heat pump depends on the temperature gradient. This is significantly higher between the hot water in the hot water reservoir and the incoming cold water than in conventional systems with a circulation line. Since no circulation line is provided, turbulence caused by the returning hot water and thus a reduction in the temperature gradient are avoided.

Some exemplary embodiments are explained in greater detail below with reference to the drawings. In the drawings:

FIG. 1 schematically shows an exemplary embodiment of a hot water system,

FIG. 2 schematically shows a further exemplary embodiment of a hot water system,

FIG. 3 schematically shows yet a further exemplary embodiment of a hot water system,

FIG. 4 schematically shows yet a further exemplary embodiment of a hot water system,

FIG. 5 shows schematic details of the exemplary embodiment of a hot water system, and

FIG. 6 schematically shows further details of the exemplary embodiment of a hot water system.

In the drawings, the same or functionally equivalent components are provided with the same reference signs.

FIG. 1 schematically shows an exemplary embodiment of a hot water system with a drinking water heater 1 with hot water reservoir 3 and, by way of example, two hot water stations 51, 52 and three tapping stations 71, 72, 73. The drinking water heater 1 heats cold drinking water flowing into the hot water reservoir 3 via a house connection 21 and stores it in the hot water reservoir 3 for tapping. Heating is carried out, for example, by a heat exchanger 15.

Between the drinking water heater 1 and the tapping stations 71, 72, 73, a line system 9 not having a circulation line is provided, which is designed so that hot water flows from the hot water reservoir 3 of the drinking water heater 1 to the tapping station 71, 72, 73. The hot water can be drawn off at the tapping stations 71, 72, 73, which can be, for example, a shower or a tap. The hot water stations 51, 52 are hot water transfer points and are connected to the drinking water heater 1 via supply lines 11. Distribution lines 13 lead from the hot water stations 51, 52 to the tapping points 71, 72, 73, 74. Several connections can be provided at the hot water stations 51, 52 for distribution lines 13 to tapping stations 71, 72, 73. Several tapping stations can advantageously be installed in series so that the distribution line to the most distant tapping station is looped through further tapping stations.

Between the drinking water heater 1 and a first tapping station 71, the hot water flows along a line path via a first hot water station 51. The line path has a first portion between the drinking water heater 1 and the first hot water station 51 and a second portion between the first hot water station 51 and the first tapping station 71. The line volume in the pipes of the line path is less than or equal to a prespecified maximum line volume of 3 liters.

Between the drinking water heater 1 and a second and third tapping station 72, 73, the hot water flows via the second hot water station 52. A line path between the drinking water heater 1 and the second tapping station 52 has a first portion between the drinking water heater 1 and the second hot water station 52 and a second portion between the second hot water station 52 and the second tapping station 72. The line volume in the line path is less than the specified maximum line volume of 3 liters. A line path between the drinking water heater 1 and the third tapping station 73 runs via the second hot water station 52 and the second tapping station 72, at which the pipe is looped through. The line path has a first portion between the drinking water heater 1 and the second hot water station 52 and a second portion between the second hot water station 52 and the third tapping station 73. The line volume in the pipes of the line path is less than the specified maximum line volume. This line path leads to the furthest tapping station 73 and extends beyond the previously described line path to the second tapping station 72. It has the largest line volume of all three line paths. The line volume in each of the line paths is less than the specified maximum line volume of 3 liters.

The hot water system is a small system in which the line volume of each line path is less than 3 liters. In addition, the volume of the water reservoir 3 is less than or equal to 400 liters.

Such a hot water system with two hot water stations 51, 52 can for example be provided for two small apartments, in each of which a hot water station 51, 52 is arranged. For a two-person apartment, one hot water station is sufficient for the tapping points in the kitchen and bathroom. Alternatively, the hot water system can be designed for a larger apartment for three to four people. One hot water station 51, 52 is then provided for each bathroom and kitchen and their tapping points. In the case of a hot water system for multiple residential units, for example in a multi-unit residential building or an apartment complex, more than two hot water stations 51, 52 are provided. Nevertheless, the hot water system is a small system.

The hot water system can be designed for very long line paths. Depending on the desired length of the longest line path, the pressure in the line system and a pipe cross-section, namely an inner pipe diameter, of the line system are selected so that the line volume of each line path is below the specified maximum line volume. The greater the desired line path length, the higher the pressure and the smaller the pipe cross-section. The line volume of each line path is less than the maximum line volume of 3 liters. The first portion up to the hot water station is advantageously optimized by allocating part of the maximum line volume to the first portion. The remaining part of the maximum line volume is available for the second portion. For example, 0.6 liters can be provided for the line volume of the second portions of the line paths after the heating stations, and 2.4 liters are provided for the line volume between the drinking water heater 1 and the first and second hot water stations 51, 52, respectively. In another embodiment, 0.5 liters are provided for the second portions and 2.5 liters for the first portions.

The hot water system does not include a circulation line or a fresh water station. This results in high economic efficiency for investment and operation. The line path can be very long so that, for example, a large building can be supplied or a drinking water heater 1 can be operated outside the house.

FIG. 2 schematically shows another exemplary embodiment of a hot water system with a drinking water heater 1 with hot water reservoir 3 as well as a hot water station 50 and a tapping station 70.

Inside the house, a house connection 21 is provided, at which drinking cold water is provided and which feeds the drinking water heater 1. The house connection 21 includes a shut-off valve, a water meter, a through valve with backflow prevention and a filter. From the house connection 21, the drinking water heater 1 is supplied with potable cold water via a pressure booster 23 at approximately 4 bar.

The drinking water heater 1 comprises a hot water reservoir 3 into which the potable cold water flows, and is designed to heat the potable cold water by a heat exchanger 15 and to provide it as potable hot water in the hot water reservoir 3. The drinking water heater 1 provides hot water at a drinking water outlet at increased pressure, for example 9 bar. Typically, the hot water in the hot water reservoir 3 has a temperature at which water bacteria can no longer multiply, for example 50 degrees Celsius. The drinking water heater 1 is coupled to a heat pump 49, which is designed to heat water in the drinking water heater 1

The hot water can flow to the hot water station 50 via a line system 9 without circulation line paths and with a supply line path 11 which is connected to a hot water station 50. Hot water that has not been drawn off and remains in the line system 9 for a longer period of time cools down. The hot water station 50 comprises a pressure regulator 31, which is designed in particular for pressure reduction, and an electric instantaneous water heater 33. One or more tapping stations 70 can be connected to the hot water station 50 via distribution lines 13. In this embodiment, a tapping point 70 is provided, which is connected to the hot water station 50 via a distribution line 13.

The instantaneous water heater 33 in the hot water station 50 is designed to heat the cooled water flowing out of the line system during a discharge time until hot water has flowed from the drinking water heater 1 to the hot water station 50. A thermal bypass valve 17 bridges the instantaneous water heater 33 as soon as hot water is available at the instantaneous water heater 33.

Since the line system 9 does not comprise a circulation line path, the hot water from the hot water reservoir 3 is only available at the tapping station 70 after the discharge time, when the cold water has flowed out of the line system 9. In the meantime, hot water is provided by means of the instantaneous water heater 33, which heats the water flowing out of the supply line 11 until the line is carrying hot water. The instantaneous water heater is then switched off and bypassed by the bypass valve 17. The fully electronic instantaneous water heater 33 with thermal bypass valve 17 allows continuous bypassing of the instantaneous water heater from 45 degrees Celsius water temperature.

In an exemplary embodiment with a short supply line 11 to the drinking water heater 1 and thus a short discharge time, the hot water station 50 can be deactivated, for example by an app.

Even in the event of an emergency, i.e., if the hot water reservoir only provides cold water and the auxiliary heating is not working, you can still take a warm shower or draw hot water with a slightly reduced flow rate thanks to the instantaneous water heater 33.

The hot water station 50 forms a hot water transfer point from the supply line 11 to the individual piping of the tapping station 70. For on-site installation of the transfer point, internal stainless steel piping with a ¼″ IG connection is provided. In one embodiment, the piping is available as a raw or finished set. Alternatively, it can already have been installed in the hot water station 50 upon delivery.

In one exemplary embodiment, such a hot water station is a device with a rectangular basic shape, which can have an exemplary size of 540×300×82 mm. It weighs approximately 9 kg, so it can be easily mounted on a wall. ½″ IG connections are provided. A typical discharge rate is 10 l/min. A 9 KW connection power is provided for the instantaneous water heater. The maximum current consumption is 3×13 A with an electrical connection of 400/16/3˜V/A.

In one embodiment, the operating temperature of the hot water station 50 is 50 degrees Celsius or 55 degrees Celsius, so that limescale deposits are reduced. The operating pressure of the hot water station 50 is permanently 6 bar, with pressure surges of up to 10 bar being possible. The hot water station 50 is also advantageously designed to electrically reheat the water provided, so that the hot water from the drinking water heater 1, which has 50 degrees Celsius, is reheated to 60 degrees Celsius in the hot water station. This increases comfort.

All water-bearing components of the hot water system are made of drinking water quality, for example copper according to DIN 50930-6, brass according to EN CW617N or stainless steel AISI 304.

The hot water system is dimensioned so that it is a small system according to DVGW work sheet W551. This means that the hot water system can be operated at economical temperatures without the need for inspection.

The maximum line path length between the drinking water heater and the transfer point is 65 m, with a maximum line volume of 2.4 liters in the first portion of the flow path. This leaves a line volume of a maximum of 0.6 liters for the second portion of the line path from the hot water station as the transfer point to the tapping stations, in order not to exceed the maximum line volume of 3 liters. By optimizing the pressure and pipe diameter in the second portion, an additional line path length of approximately 9 m can be achieved.

The following lists combinations of pipes and pressure for various line path lengths between the drinking water heater and the hot water transfer point, which also do not exceed the maximum line volume of 3 liters. A maximum line volume of 2.4 liters is provided for the flow path through the supply line between the drinking water heater and the hot water transfer point. The pipes for the line system can, for example, be made of polyethylene with increased temperature resistance, PE-RT for short.

With 7×4.5 mm pipes (i.e., 7 mm inner diameter and 4.5 mm wall thickness) with an outer diameter of 16 mm, a maximum line path length of 65 m can be achieved. The pressure is 20.81 bar, so that a flow rate of 10 l/min of unmixed hot water can be achieved. The system requires a pressure regulator 31 and, to achieve the pressure in the supply line 11, also a pressure booster 23, as shown in FIG. 2. For other dimensions, these components are optional.

With 8.4×3.8 mm pipes, which have an outer diameter of 16 mm, a maximum line path length of 45 m can be achieved. The pressure is 6.01 bar, so that a flow rate of 10 l/min of unmixed hot water can be achieved. A pressure booster 23 is required for the system.

With 9.6×3.2 mm pipes, which have an outer diameter of 16 mm, a maximum line path length of 35 m can be achieved. The pressure is 2.47 bar, so that a flow rate of 10 l/min of unmixed hot water can be achieved. For the system, a pressure booster 23 is required at a pressure below 6 bar.

With 11.6×2.2 mm pipes, which have an outer diameter of 16 mm, a maximum line path length of 25 m can be achieved. The pressure is 0.71 bar, so that a flow rate of 10 l/min of unmixed hot water can be achieved.

FIG. 3 schematically shows another exemplary embodiment of a hot water system. It comprises a drinking water heater 1 with hot water reservoir 3 as well as a hot water station 50 and two tapping stations 71, 72. The drinking water heater 1 heats cold drinking water flowing into the hot water reservoir 3 via a house connection 21 and stores it in the hot water reservoir 3 for tapping. Heating is carried out, for example, by a heat exchanger 15. For example, the hot water in hot water reservoir 3 has a temperature of 52 degrees Celsius. The temperature in the line paths can range from 20 to 51 degrees Celsius due to cooling if no water has been drawn for a long time.

Between the drinking water heater 1 and the tapping stations 71, 72, a line system 9 not having a circulation line is provided, through which hot water flows from the hot water reservoir 3 to the tapping station 71, 72. The hot water station 50, which is a hot water transfer point, is coupled via a supply line 11 to the drinking water heater 1. Distribution lines 13 lead from the hot water stations 50 to the tapping points 71, 72. The tapping points 71, 72 are installed in series so that the distribution line 13 is looped through the first tapping station 71 to the most distant second tapping station 72. The sketched cold water line path 19 is connected in a similar way.

The requirements and exemplary dimensions already mentioned in the previous exemplary embodiments apply to the dimensioning of the supply line 11 and the distribution line 13. The line volume in the pipes of the line path is less than or equal to a specified maximum volume of 3 liters. The volume of the supply line 11 is a maximum of 2.5 liters. The volume of the supply line 13 to the most distant tapping point 72 is a maximum of 0.5 liters.

During a discharge time, until hot water has flowed from the drinking water heater 1 to the hot water station 50, hot water can already be drawn from the small hot water reservoir 60. In this exemplary embodiment, a bypass valve can also be provided which bridges the hot water reservoir as soon as hot water from the drinking water heater 1 is available at the hot water station 50. Alternatively, the water is passed through the hot water station 50 regardless of its temperature, so that a regular water exchange takes place.

The hot water station 50 comprises a small hot water reservoir 60 that stores water. The storage volume of the small hot water reservoir 60 is less than that of the hot water reservoir 3 in the drinking water heater 1. A typical value is 5 liters. The storage volume of the small water reservoir 60 is not counted as part of the line volume, which should be less than a maximum volume. However, the total volume of all water reservoirs in the system must be less than a maximum storage volume in order to be exempt from the inspection requirement. According to the Drinking Water Ordinance, the maximum storage volume is less than 400 liters.

The small hot water reservoir 60 has a thermal insulation 62, which greatly slows down the cooling of stored hot water. The small hot water reservoir 60 is also designed to heat the water electrically, so that warm drinking water is available in the small hot water reservoir 60, even if no water has been drawn off for a longer period of time. In one exemplary embodiment, heating to 60 degrees Celsius is provided after a longer period of downtime. Heating can occur for example as soon as the temperature of the stored water has dropped below a prespecified threshold, until the temperature in the small hot water reservoir 60 has risen above a further prespecified threshold. For heating, a heating element 66 is provided, which can have an exemplary power of 100 watts.

The small hot water reservoir 60 comprises a heat exchanger 64, for example a plate heat exchanger, with a primary circuit for the drinking water and a secondary circuit with phase change material, or PCM for short. Alternative exemplary embodiments of the heat exchanger include finned tubes or aluminum bodies with a large surface area. The phase change material stores a large part of the thermal energy supplied to it from the primary circuit in the form of latent heat (in particular during the phase change from solid to liquid). The phase change can occur at approximately 45 degrees Celsius when the waxy phase change material melts. The phase change occurs below the desired temperature for the hot water. Hot water flowing through and/or heated causes a phase change of the phase change material and stores part of the thermal energy of the hot water. Nevertheless, even after hot water has passed through, the thermal energy of which has been partially used for the phase change, sufficient hot water is provided at the tapping station. If there has been no tapping for a long period of time, the thermal energy stored in the phase change material serves to slow down the cooling of the stored water. The phase change material solidifies and discharges into the stored water the thermal energy released during this and heats it.

For example, hot water from the supply line at approximately 50 degrees Celsius can cause the phase transition of the phase change material, which liquefies in this temperature range. Nevertheless, water at approximately 40 degrees Celsius can still be drawn from the tapping station 71, 72.

The combination of heat exchanger 64 with phase change material, heating element 66, and thermal insulation 62 significantly reduces the energy required to provide hot water near the tapping stations 71, 72. Compared to an instantaneous water heater, the energy requirement for the hot water station 50 is reduced to approximately one-seventh. The thermal insulation 62 can maintain the water temperature for at least 24 hours, so that the hot water can be tapped without reheating. The hot water station 50 can provide hot water at the tapping stations 71, 72 after just 8 to 15 seconds. In addition, the lower pressure loss of the plate heat exchanger makes possible a discharge capacity of 15 liters/min. This means that the discharge capacity and the hot water supply time are superior to the previous example with an instantaneous water heater.

The hot water station 50 with small hot water reservoir 60 has almost the same dimensions as a hot water station 50 with instantaneous water heater 33. However, due to thermal insulation 62, the depth is usually greater. The connections and fittings are the same.

The tapping stations 71, 72 in this exemplary embodiment of a system each have a miniature heat store 80 in which hot water can be stored in the immediate vicinity of the outflow from the tapping stations 71, 72. The small heat store 80 is a compact, small heat store that is designed, for example, as an under-counter heat store. It can typically store about 0.5 liters of water. The optional miniature heat store 80 increases convenience terms of the hot water supply time. It is reduced to less than 8 seconds. A typical value is 5 seconds.

The miniature heat store 80 comprises thermal insulation to slow down the cooling of the water. Advantageously, also provided in the miniature heat store 80 are a heating element and a heat exchanger with phase change material, the operation of which has been described above. The electrical power consumption is around 50 watts.

The storage volume of the miniature heat store 80 is also not included in the line volume, which must be less than the maximum volume to be considered a small system. However, the storage volume of the miniature heat store 80 counts towards the total volume of all water reservoirs in the system, which must be less than a maximum storage volume to be exempt from the obligation to check.

Since the storage volumes of the small hot water reservoir and the miniature heat store are not part of the line volume, the maximum line volume is not exceeded in this exemplary embodiment either.

The highly efficient serial small hot water reservoir 60 in the hot water station 50, in particular in combination with the optional miniature heat stores 80, makes a significantly shorter time possible before the hot water is available at the tapping stations than a conventional system.

The hot water station with small hot water reservoir and the miniature heat store have very low electrical energy consumption, in particular compared to the hot water station in comparison with the hot water station with instantaneous water heater. The power consumption of the optional miniature heat stores and the hot water station 50 with small hot water reservoir 60 is almost negligible compared to the power consumption of the hot water station 50 with instantaneous water heater 33. This advantage is particularly important in large systems with many hot water stations 50 and thus also many residential units. Due to the low energy consumption, with an exemplary power consumption of 50 to 100 watts, the total mains connection power is significantly lower compared to a conventional system, but also compared to the previous exemplary embodiment. If there are multiple hot water stations 50, a simultaneity lock to limit the number of hot water stations 50 operating simultaneously is no longer required. Smaller cable cross-sections can be used for the power supply. Additional transformer stations are not required. This overall lower cost for the power supply also leads to less planning outlay for the system and in particular for the electrical supply.

FIG. 4 schematically shows another exemplary embodiment of a hot water system. The following description focuses on differences from the previous exemplary embodiment from FIG. 3.

In this exemplary embodiment, two hot water branches 10, 20 are provided, through which, on the one hand, hot water from the drinking water heater 1 is conducted to a first and a second tapping station 71, 72 in the first hot water branch 10 and, on the other hand, hot water from the drinking water heater 1 is conducted to a third and a fourth tapping station 73, 74 in the second water branch 20. Although the hot water branches 10, 20 are separate, so that no water exchange occurs, they both run through the same hot water station 50. They have separate supply lines 11 and separate distribution lines 13. The hot water branches 10, 20 are constructed with a looped-through installation and miniature heat stores 80, as in the previous exemplary embodiment.

As in the previous exemplary embodiment, the hot water station 50 comprises a small hot water reservoir 60, a thermal insulation 62, a heat exchanger 64 and a heating element 66. Since the hot water station 50 is provided for two hot water branches 10, 20, it has two connections for their distribution lines 13. The housing dimensions are also larger than in the previous exemplary embodiment, since it stores more water, to supply two branches 10, 20.

In each of the branches 10, 20, the line volume in the pipes of the line path is less than or equal to the prespecified maximum line volume of 3 liters.

The two water branches 10, 20 run as two primary circuits of the heat exchanger 64 through the same hot water station 50. FIG. 5 schematically shows the hot water station 50 with inflowing and outflowing water 111, 131 of the first branch 10 and with inflowing and outflowing water 112, 132 of the second branch 20. There is no mixing of the drinking water between the branches 10, 20. Mixing also does not occur in the hot water station 50 either. In addition to separate distribution lines 13, the hot water branches 10, 20 also have separate supply lines 11 which run between the drinking water heater 1 and the hot water station 50.

The secondary circuit of the heat exchanger 64 comprises phase change material and interacts with both primary circuits so that thermal coupling occurs through the secondary circuit, as heat from each of the primary circuits can be stored in the secondary circuit and be discharged from the secondary circuit to each of the primary circuits. In this way, the phase change material can be charged by one primary circuit, and then the stored thermal energy can be transferred to the other primary circuit.

FIG. 6 shows schematically a detail of an exemplary embodiment of a heat exchanger 64 for the previous exemplary embodiment from FIG. 5, which is designed as a plate heat exchanger, for example. Between the plates, phase change material 68 and the water of the first and second branches 10, 20 are provided alternately. However, the water of the first branch 10 in the primary circuit flows through the plates spatially separated from the water of the second branch 20 in the secondary circuit, preferably in alternation, so that the water in the first branch 10 flows past the phase change material 68 between two adjacent plates on one side and the water in the second branch 20 flows past said material on the other side. As a result, the thermal energy stored in the phase change material 68 can be transferred to both the first and the second primary circuits, even if the storage of the thermal energy was caused only by the tapping in one of the branches 10, 20. Nevertheless, both primary circuits can charge the phase change material 68.

For example, a shower in the first branch 10, in which a lot of hot water is typically drawn over a longer period of time, can cause thermal energy to be stored in the secondary circuit. This stored thermal energy can then be released for water extraction in the kitchen in the second branch 20, but also, for example, for washing hands in the bathroom, which is connected to the first branch 10.

The other features of the hot water station and their use, namely the thermal insulation and the heating of the stored water, previously described in conjunction with FIG. 3, are also provided in the hot water station in FIGS. 4 to 6 in order to heat the water in the hot water station for both branches 10, 20 and to slow down its cooling. In this way, the thermal insulation 61 can keep the hot water hot enough for tapping for up to 24 hours. In this exemplary embodiment, a 100-watt heating element 66 is also provided with which the cooled water in the small hot water reservoir 60 can be heated to 60 degrees Celsius after a longer period of downtime.

The exemplary embodiment described in conjunction with FIGS. 4 to 6 has the same advantages as the exemplary embodiment described in conjunction with FIG. 3. In both hot water branches 10, 20, the output volume is below a prespecified value; in particular, it is equal to or less than three liters. The discharge capacity is higher, at more than 20 liters/min, due to the tapping stations 71, 72, 73, 74 being supplied by two hot water branches 10, 20. The drinking water supply is more stronger even though less energy is required. Planning and implementation are also simplified, as only one installation route is provided instead of two if two heat stations 50 were provided for the two hot water branches. Even if the heat station 50 has the same or similar power consumption of 100 W as in the previous exemplary embodiment, the provision of the stored thermal energy for both primary circuits leads to an increase in efficiency.

The components of a hot water system described above in conjunction with the figures can be supplied by a manufacturer and then installed on site, particularly in combination with a heat pump which is also used to heat the drinking water. In such an embodiment, the components are optimized for operation with a heat pump. The drinking water heater 1 has a very good efficiency because there is no turbulence or mixing caused by the hot water flowing back into the heat store 3, as would be the case with a circulation line. The circulation line-free line system 9 leads to a high efficiency of the hot water system, since the efficiency of the heat pump depends on the temperature gradient.

The features indicated above and in the claims, as well as the features which can be seen in the figures, can advantageously be implemented both individually and in various combinations. The invention is not limited to the described exemplary embodiments, but can be modified in many ways within the scope of the capabilities of a person skilled in the art.

List of Reference Signs

• • 1 drinking water heater
  • 3 hot water reservoir
  • 9 line system
  • 11 supply line
  • 13 distribution line
  • 15 heat exchanger
  • 17 bypass valve
  • 19 cold water line
  • 21 house connection
  • 23 pressure booster
  • 31 pressure regulator
  • 33 instantaneous water heater
  • 49 heat pump
  • 50, 51, 52 hot water station
  • 60 small hot water reservoir
  • 62 thermal insulation
  • 64 heat exchanger
  • 66 heating element
  • 68 phase change material
  • 70, 71, 72, 73, 74 tapping station
  • 80 miniature heat store