WO2024099813A1

WO2024099813A1 - Hot water system

Info

Publication number: WO2024099813A1
Application number: PCT/EP2023/080246
Authority: WO
Inventors: Alexander Schechner
Original assignee: Envola GmbH
Priority date: 2022-11-10
Filing date: 2023-10-30
Publication date: 2024-05-16
Also published as: DE102022129809A1

Abstract

The invention relates to a hot water system comprising: - a drinking water heater (1) having a hot water storage tank (3), - an extraction station (70, 71, 72, 73, 74), - a circulation line-free line system (9) between the drinking water heater (1) and the extraction station (70, 71, 72, 73, 74), which line system is designed so that heated drinking water flows from the drinking water heater (1) along a line path in the line system (9) to the extraction station (70, 71, 72, 73, 74), wherein a pressure in the line system and a tube 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 predefined maximum line volume, and wherein the line path comprises a first portion and a second portion, and a hot water station (50, 51, 52) is provided in the line system (9) between the first portion and the second portion and is designed to heat and/or store the drinking water.

Description

HOT WATER SYSTEM

The invention relates to a hot water system.

A hot water system comprises a drinking water heater with a hot water tank and one or more extraction stations to which hot water flows from the drinking water heater through a pipe system.

Long pipe runs mean that providing hot water from the drinking water heater to the extraction stations takes a significant amount of time. If no water is drawn off, the water stagnates in the pipe system and cools down. Water standing in the pipe system for a longer period of time can lead to a hygiene problem if water bacteria, such as legionella, multiply rapidly.

In conventional pipe systems with long pipe runs, a circulation pipe is provided for reasons of comfort. This causes hot water to circulate in the pipe system and thus always flows past or close to the extraction points, so that hot water is available at the extraction points immediately or after a short time. If the circulating hot water is at a sufficiently high temperature, water bacteria are killed, so that hygiene problems are reduced. However, a pump is required for the circulation, which consumes just as much energy as heating the circulating hot water. Heating the constantly circulating drinking water to around 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 losses caused by heat pumps occur at around 60 degrees Celsius. The circulating drinking water also leads to mixing of the drinking water stored in the hot water tank, which has a negative impact on the performance of the heat pump. These effects lead to a loss of approximately 50% of the energy used.

If the volume in the pipes between the drinking water heater and at least one of the draw-off points is greater than 3 liters, a circulation pipe or temperature-maintaining bands are mandatory for hygienic reasons in accordance with the legal requirements in Germany.

According to the German Drinking Water Ordinance, a distinction is made between small systems and large systems. In small systems, the volume in the pipes between the drinking water heater and the extraction points is less than or equal to 3 liters. In addition, the capacity of the hot water tank of the drinking water heater is less than or equal to 400 liters. If these requirements are not met, it is a large system; unless the hot water system is in a single or two-family house. For a large system in public or commercial buildings, including rented apartments, an annual microbiological drinking water test must be carried out. This test requirement 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 extraction 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 extraction 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 extraction stations is controlled in such a way that when water is drawn from a household appliance the water is not reheated, but is reheated 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 extraction stations. If the temperature falls below a minimum, the water is passed through a pipe branch in which 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 extraction stations. A parallel second line with an additional heat source can provide additional hot water if required.

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

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

The hot water system is free of circulation pipes; this means that there is no circulation pipe in which hot water constantly flows in a circle. This saves energy. In a system with a heat pump, around 50% of energy is saved compared to a system with a circulation pipe due to the lack of circulation, as the effort required to heat and circulate 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 tank. Advantageously, there is no fresh water station in the pipe system that uses heat from a water-based central heating system to heat the water continuously, so the effort required 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 tank. The hot water typically has a temperature in the range of 45 to 60 degrees Celsius, in particular 50 to 60 degrees Celsius, and can be taken from the extraction station. Several extraction stations can be provided in the hot water system. Examples of extraction stations are taps and showers.

The pipe volume of the pipe route is the volume of the pipes in the pipe system along which the water flows from the drinking water heater to the extraction station. The dimensioning of pressure and pipe cross-section, in particular the inner pipe diameter, depends on the length of the pipe route and the specified maximum pipe volume between the drinking water heater and the extraction station. The maximum pipe volume is low for hygienic reasons. The maximum pipe volume is advantageously in accordance with legal or structural specifications. A small system in the sense of the German Drinking Water Ordinance, in particular DVGW Worksheet W 551, has a maximum pipe volume of 3 liters, so that the mandatory annual microbiological drinking water test is not required for such a system.

In comparison to a conventional hot water system, in which the length of pipes with a predetermined pipe cross-section is limited by the predetermined maximum pipe 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 pipe length despite the predetermined maximum pipe volume. When adjusting the pipe cross-section, the inner pipe diameter is adjusted. The greater the desired pipe length, the higher the pressure and the smaller the pipe cross-section, i.e. the inner pipe diameter. The higher pressure is also accompanied by a higher flow velocity, so that there are fewer deposits in the pipes and bacterial growth is inhibited. The length of the pipe route between the drinking water heater and the extraction station is longer than in conventional hot water systems without a circulation line. The length of the pipe route 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 section and the second section, a hot water station is provided in the pipe system through which the drinking water flows. The hot water station is designed to supply hot water provided on the inlet side to heat and/or store. If the previously heated drinking water has been standing in the pipes for a long time because no hot water was 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 can have flowed from the hot water tank in the hot water station or it can 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 tank, but the hot water station advantageously heats the water to a higher temperature, for example 60 degrees Celsius. Preheating and/or temporary storage by the hot water station improves comfort because hot water is available at the drawing station more quickly than if no hot water station were provided and the cold water in the pipes had to flow away 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 extraction points, which is formed by distribution lines between the hot water station and the extraction points. The first section of the line is the supply line. The second section is the distribution line between the hot water station and the extraction point. The hot water station has connections for the distribution line and thus feeds a hot water branch. In a small residential unit, one hot water branch is usually provided for the kitchen and bathroom. In a larger residential unit, two hot water branches are often provided, separately for the kitchen and bathroom.

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

The first pressure is advantageously different from a second pressure in the second section. In order to bridge a long distance with the supply line, the hot water flows in it at high pressure. This pressure is reduced in the hot water station. In one version, a pressure booster is installed upstream of the drinking water heater in order to achieve high pressure in the first section. 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 extraction stations are connected to the hot water station, with the pipe volumes in each pipe path between the drinking water heater and the additional extraction station or one of the additional extraction stations being less than or equal to the specified maximum pipe volume. The pipe volume for the pipe path to each extraction station is therefore less than or equal to the maximum pipe volume. The pipe path to the extraction station furthest away from the drinking water heater usually has the largest pipe volume, so as a rule of thumb when dimensioning it is sufficient that this pipe volume is less than or equal to the maximum pipe volume. Additional extraction stations can be provided between the furthest extraction station and the drinking water heater, which are advantageously connected to one another by a loop-through installation. The following are examples of inner pipe diameters and pressures for given maximum pipe lengths. For example, in the hot water system, the inner pipe diameter can be less than or equal to 11.6 mm. The pressure is then advantageously greater than or equal to 0.71 bar. This allows a pipe length to the hot water station of 25 m to be achieved. For example, the inner pipe diameter can be less than or equal to 9.6 mm. The pressure is then advantageously greater than or equal to 2.47 bar. This allows a pipe length to the hot water station of 35 m to be achieved. For example, the inner pipe diameter can be less than or equal to 8.4 mm. The pressure is then advantageously greater than or equal to 6.01 bar. This allows a pipe length to the hot water station of 45 m to be achieved. For example, the inner pipe diameter can be less than or equal to 7 mm. The pressure is then advantageously greater than or equal to 20.81 bar. This allows a pipe length to the hot water station of 65 m to be achieved. This maximum pipe length significantly exceeds the pipe path in a conventional hot water system without a circulation pipe. In the examples mentioned above, the pipes can have an external diameter of 16 mm to facilitate assembly and installation through uniform pipe external dimensions.

In one version, the hot water station includes a continuous flow heater that is designed to heat water during a discharge time until hot water from the drinking water heater has reached the hot water station. This increases comfort in the case of long supply lines, as hot water is immediately available at the extraction station, even if the water in the line is already cold when it is drawn.

In one version, the hot water station includes a bypass valve that bypasses 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 predetermined minimum temperature bypasses the instantaneous water heater.

Nevertheless, an additional heater can be provided in the hot water station, which additionally heats the hot water from the drinking water heater.

In one version, the hot water station includes a small hot water tank whose storage capacity is less than that of the hot water tank of the drinking water heater. In this version, the hot water station acts as a decentralized buffer that provides hot water closer to the extraction stations and thus shortens the time until hot water is available at the extraction stations.

The small hot water tank advantageously 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. In addition or alternatively, the small hot water tank is designed to heat water stored in it. This makes it possible to heat the cooled water again during a longer period of downtime in which no water has been taken from the small hot water tank and hot water has flowed in from the drinking water heater. Alternatively, the stored water can be heated when it cools below a predetermined threshold to counteract the cooling, so that hot water is always available in the small hot water tank 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 tank has a heat exchanger. The heat exchanger contains a phase change material, abbreviated to “PCM”. The drinking water flows in the primary circuit of the heat exchanger. The secondary circuit contains the phase change material, which absorbs a large part of the water supplied to it. thermal energy from the primary circuit in the form of latent heat (for example during a phase change from solid to liquid). Hot water flowing through and/or stored in the hot water station causes a phase change in 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 withdrawal station, particularly when hot water is flowing through. The phase change material can, for example, be wax-like and liquefy when heat is applied. If nothing has been drawn for a long time, the latent heat stored in the phase change material is used to heat the cooling water in order to counteract the cooling. The phase change material solidifies again and releases the thermal energy released in the process to the stored water. Electrical heating can support the provision of hot water by heating the stored water when it cools below a predetermined threshold, possibly several times, to counteract the cooling, so that hot water is always available in the small hot water tank for use. The energy required for this is significantly lower than if no phase change material were provided.

In one version, the heat exchanger of the small hot water tank has two separate drinking water primary circuits and a secondary circuit containing the phase change material. This version 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 kitchen of an apartment. The pipes of the two branches are separate from each other. There is no water exchange. However, there is a thermal coupling through the secondary circuit, as 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. With other In other words: there is a heat exchange between each of the two primary circuits, which are separated from each other, and the secondary circuit, without any water exchange between the two primary circuits. There can also be more than two primary circuits that are thermally coupled in this way.

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

The water tank can also be bypassed by a bypass valve if sufficient hot water has already been stored. However, regular flow of hot water also benefits the regular charging of the phase change material that acts as a storage tank.

In one version, the drinking water heater is coupled to a heat pump, so that the heat pump heats drinkable cold water to hot water. The pipe system without circulation pipes 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 tank and the incoming cold water than in conventional systems with a circulation pipe. Since no circulation pipe is provided, turbulence caused by the hot water flowing back is avoided, thus reducing the temperature gradient. Some examples of implementation are explained in more detail below using the drawing. They show:

Figure 1 shows schematically an embodiment of a hot water system,

Figure 2 shows schematically another embodiment of a hot water system,

Figure 3 shows schematically yet another embodiment of a hot water system,

Figure 4 shows schematically yet another embodiment of a hot water system,

Figure 5 schematically shows details of the embodiment of a hot water system, and

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

In the figures, identical or functionally equivalent components are provided with the same reference symbols.

Figure 1 shows a schematic of an embodiment of a hot water system with a drinking water heater 1 with a hot water tank 3 and, for example, two hot water stations 51, 52 and three extraction stations 71, 72, 73. The drinking water heater 1 heats cold drinking water flowing into the hot water tank 3 via a house connection 21 and stores it in the hot water tank 3 for extraction. The heating takes place, for example, by a heat exchanger 15. Between the drinking water heater 1 and the extraction stations 71, 72, 73 there is a pipe system 9 which is free of circulation lines and is designed so that hot water flows from the hot water tank 3 of the drinking water heater 1 to the extraction stations 71, 72, 73. The hot water can be extracted from the extraction stations 71, 72, 73, which are, for example, a shower or a water tap. The hot water stations 51, 52, which are hot water transfer points, 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 extraction points 71, 72, 73. Several connections can be provided on the hot water stations 51, 52 for distribution lines 13 to extraction stations 71, 72, 73. Several extraction stations can advantageously be installed in series so that the distribution line to the most distant extraction station is looped through further extraction stations.

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

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

The hot water system is a small system in which the pipe volume of each pipe route is less than 3 liters. In addition, the volume of the water tank 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, each of which has a hot water station 51, 52. For a two-person apartment, one hot water station for the outlets in the kitchen and bathroom is sufficient. Alternatively, the hot water system can be provided for a larger apartment for three to four people. One hot water station 51, 52 is then provided for the bathroom and kitchen and their outlets. In a hot water system for several 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 pipe runs. Depending on the desired length of the longest pipe run, the pressure in the pipe system and a pipe cross-section, namely an inner pipe diameter, of the pipe system are selected so that the pipe volume of each pipe run is below the specified maximum pipe volume. The greater the desired pipe length, the higher the pressure and the smaller the pipe cross-section. The pipe volume of each pipe run is less than the maximum pipe volume of 3 liters. The first section up to the hot water station is advantageously optimized by allocating part of the maximum pipe volume to the first section. The remaining part of the maximum pipe volume is available for the second section. For example, 0.6 liters can be provided for the pipe volume of the second sections of the pipe runs after the heating stations, and 2.4 liters are provided for the pipe volume between the drinking water heater 1 and the first or second hot water station 51, 52. In another embodiment, 0.5 liters are provided for the second sections and 2.5 liters for the first sections.

The hot water system does not have a circulation line or a fresh water station. This results in a high level of economic efficiency for investment and operation. The line route 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.

Figure 2 shows schematically another embodiment of a hot water system with a drinking water heater 1 with hot water storage tank 3 as well as a hot water station 50 and a withdrawal station 70. A house connection 21 is provided inside the house, from which drinkable cold water is provided and which feeds the drinking water heater 1. The house connection 21 comprises a shut-off valve, a water meter, a straight-way valve with backflow prevention and a filter. The drinking water heater 1 is fed with drinkable cold water from the house connection 21 via a pressure booster 23 with approximately 4 bar.

The drinking water heater 1 comprises a hot water tank 3 into which the drinkable cold water flows, and is designed to heat the drinkable cold water through a heat exchanger 15 and to provide it as drinkable hot water in the hot water tank 3. The drinking water heater 1 provides the hot water at a drinking water outlet with increased pressure, for example 9 bar. The hot water in the hot water tank 3 usually 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 pipe system 9 without circulation pipes and with a supply pipe 11, which is connected to a hot water station 50. Hot water that is not drawn off and remains in the pipe 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 to reduce pressure, and an electric continuous flow heater 33. One or more withdrawal stations 70 can be connected to the hot water station 50 via distribution pipes 13. In this exemplary embodiment, a withdrawal point 70 is provided, which is connected to the hot water station 50 via a distribution pipe 13. The flow heater 33 in the hot water station 50 is designed to heat the cooled water flowing out of the pipe 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 bypasses the flow heater 33 as soon as hot water is available at the flow heater 33.

Since the pipe system 9 does not include a circulation pipe, the hot water from the hot water tank 3 is only available at the extraction station 70 after the discharge time, when the cold water has flowed out of the pipe system 9. In the meantime, hot water is provided by means of the flow heater 33, which heats the water flowing out of the supply pipe 11 until the pipe is carrying hot water. The flow heater is then switched off and bypassed by the bypass valve 17. The fully electronic flow heater 33 with thermal bypass valve 17 allows the flow heater to be continuously bypassed from a water temperature of 45 degrees Celsius.

In an 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 tank only provides cold water and additional heating does not work, 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 extraction station 70. For the on-site installation of the transfer point, an internal piping made of stainless steel with a

IG connection is provided. The piping is in One design example is available as a raw or finished set. Alternatively, it can already be mounted on the hot water station 50 upon delivery.

In one embodiment, such a hot water station is a device with a rectangular basic shape, which can have an exemplary size of 540x300x82 mm. The weight is approximately 9 kg, so that it can be easily mounted on a wall. 1" IG connections are provided. A typical draw-off quantity is 10 l/min. A 9 kW connection power is provided for the instantaneous water heater. The maximum current consumption is 3 x 13 A with an electrical connection of 400/16/3 ~ V/A.

The operating temperature of the hot water station 50 is 50 degrees Celsius or 55 degrees Celsius in one embodiment, 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 is 50 degrees Celsius, is reheated to 60 degrees Celsius in the hot water station. This increases comfort.

All water-carrying components of the hot water system are made of drinking water quality, for example from 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 in accordance with DVGW worksheet W551. This means that the hot water system can be operated at economical temperatures without the need for inspection.

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

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

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

With 8.4 x 3.8 mm pipes, which have an external diameter of 16 mm, a maximum pipe length of 45 m can be achieved. The pressure is 6.01 bar, so that a discharge capacity of 10 l/min of unmixed hot water can be achieved. A pressure booster 23 is required for the system. A maximum pipe length of 35 m can be achieved with 9.6 x 3.2 mm pipes with an external diameter of 16 mm. The pressure is 2.47 bar, so that a discharge capacity of 10 l/min of unmixed hot water can be achieved. The system requires a pressure booster 23 at a pressure below 6 bar.

With 11.6 x 2.2 mm pipes, which have an outer diameter of 16 mm, a maximum pipe 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.

Figure 3 shows a schematic of another embodiment of a hot water system. It comprises a drinking water heater 1 with a hot water tank 3 as well as a hot water station 50 and two extraction stations 71, 72. The drinking water heater 1 heats cold drinking water flowing into the hot water tank 3 via a house connection 21 and stores it in the hot water tank 3 for extraction. The heating is carried out, for example, by a heat exchanger 15. The hot water in the hot water tank 3 has a temperature of 52 degrees Celsius, for example. The temperature in the pipes can be in the range of 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 extraction stations 71, 72, a circulation line-free pipe system 9 is provided, through which hot water flows from the hot water tank 3 to the extraction stations 71, 72. The hot water station 50, which is a hot water transfer point, is coupled to the drinking water heater 1 via a supply line 11. Distribution lines 13 run from the hot water stations 50 to the extraction points 71, 72. The extraction points 71, 72 are installed in series, so that the distribution line 13 is looped to the most distant second extraction station 72 through the first extraction station 71. The sketched cold water line 19 is connected in a similar way.

The requirements and exemplary dimensions already mentioned in the previous 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 up to the furthest extraction 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 taken from the small hot water tank 60. In this embodiment, too, a bypass valve can be provided that bridges the hot water tank 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 includes a small hot water tank 60 that stores water. The storage volume of the small hot water tank 60 is less than that of the hot water tank 3 in the drinking water heater 1 . A typical value is 5 liters. The storage volume of the small hot water tank 60 does not count towards the pipe volume, which should be less than a maximum volume. However, the total volume of all water tanks 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 tank 60 has thermal insulation 62, which slows down the cooling of stored hot water. The small hot water tank 60 is also designed to heat the water electrically, so that warm drinking water is available in the small hot water tank 60, even if no water has been drawn off for a long time. In one embodiment, heating to 60 degrees Celsius is provided after a long period of inactivity. Heating can take place, for example, as soon as the temperature of the stored water has fallen below a predetermined threshold, until the small hot water tank 60 has risen above another predetermined threshold. A heating element 66 is provided for heating, which can have an exemplary output of 100 watts.

The small hot water tank 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 have 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 take place at approximately 45 degrees Celsius when the waxy phase change material melts. The phase change takes place below the desired temperature for the hot water. Hot water flowing through and/or heated up 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 flowed through, the thermal energy of which has been partially used for the phase change, sufficient hot water is provided at the withdrawal station. If no withdrawal has taken place for a long time, the thermal energy stored in the phase change material serves to To slow down the cooling of the stored water. The phase change material solidifies and the thermal energy released is transferred to the stored water and heats it up.

For example, water from the supply line that is approximately 50 degrees Celsius can cause the phase transition of the phase change material that liquefies in this temperature range. Nevertheless, water that is approximately 40 degrees Celsius can still be withdrawn at the withdrawal stations 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 extraction stations 71, 72. Compared to a continuous flow heater, the energy required 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 extracted without reheating. The hot water station 50 can provide hot water at the extraction stations 71, 72 after just 8 to 15 seconds. In addition, the lower pressure loss of the plate heat exchanger enables a discharge capacity of 15 liters/min. The discharge capacity and the hot water supply time are therefore superior to the previous embodiment with a continuous flow heater.

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

The removal stations 71, 72 have in this embodiment of a

System has a small heat storage unit 80 in which hot water is stored in in the immediate vicinity of the outlet from the extraction stations 71, 72. The small heat storage unit 80 is a compact small heat storage unit, which is designed, for example, as an under-counter heat storage unit. It can typically store around 0.5 litres of water. The optional small heat storage unit 80 increases comfort in terms of the hot water supply time. This is reduced to less than 8 seconds. 5 seconds is a typical value.

The small heat storage unit 80 includes thermal insulation to slow down the cooling of the water. Advantageously, the small heat storage unit 80 also includes a heating element and a heat exchanger with phase change material, the mode of operation of which has been described above. The electrical power consumption is in the range of 50 watts.

The storage volume of the smallest heat storage 80 is also not included in the pipe volume, which must be less than a maximum volume in order to be considered a small system. However, the storage volume of the smallest heat storage 80 is included in the total volume of all water storage tanks in the system, which must be less than a maximum storage volume in order to be exempt from the inspection requirement.

Since the storage volumes of small hot water tanks and small heat storage tanks are not part of the pipe volumes, the maximum pipe volume is not exceeded in this embodiment either.

The highly efficient serial small hot water storage tank 60 in the hot water station 50, especially in combination with the optional small heat storage tanks 80, enables a significantly shorter time until the hot water is available at the extraction stations than a conventional system. The hot water station with small hot water storage tank and the small heat storage tanks have a very low electrical energy consumption, especially in comparison to the hot water station with instantaneous water heater. The power consumption of the optional small heat storage tanks and the hot water station 50 with small hot water storage tank 60 can be almost neglected in comparison to the power consumption of the hot water station 50 with instantaneous water heater 33. This advantage is particularly evident in large systems with many hot water stations 50, and thus also many residential units. The low energy consumption with an exemplary power consumption of 50 to 100 watts results in a significantly smaller total network connection power compared to a conventional system, but also compared to the previous embodiment. With several hot water stations 50, a simultaneity lock to limit the number of hot water stations 50 operating simultaneously is no longer necessary. Smaller cable cross-sections can be used for the power supply. Additional transformer stations are not required. This overall lower cost of power supply also leads to lower planning costs for the system and in particular the electrical supply.

Figure 4 shows a schematic of another embodiment of a hot water system. The following description focuses on differences from the previous embodiment in Figure 3.

In this embodiment, two hot water branches 10, 20 are provided, through which, on the one hand, hot water from the drinking water heater 1 is led to a first and second extraction station 71, 72 in the first water branch 10 and, on the other hand, hot water from the drinking water heater 1 is led to a third and fourth extraction station 73, 74 in the second water branch 20. Although the hot water branches 10, 20 are separate, so that no water exchange takes place, 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 looped installation and small heat storage units 80 as in the previous embodiment.

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

In each of the branches 10, 20, the pipe volume in the pipes of the pipe path is less than or equal to the specified maximum pipe 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. Figure 5 shows schematically 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. There is also no mixing in the hot water station 50. The hot water branches 10, 20 have separate distribution lines 13 as well as 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 through the secondary circuit, because heat from each of the primary circuits can be stored in the secondary circuit and released from the secondary circuit into each of the primary circuits. This allows the phase change material to be charged by one primary circuit and then the stored thermal energy released to the other primary circuit.

Figure 6 shows a schematic section of an embodiment of a heat exchanger 64 for the previous embodiment from Figure 5, which is designed as a plate heat exchanger by way of example. Phase change material 68 and the water from the first and second branches 10, 20 are provided alternately between the plates. However, the water from the first branch 10 in the primary circuit flows through the plates spatially separated from the water from the second branch 20 in the secondary circuit, preferably alternately, so that the water from the first branch 10 flows past the phase change material 68 between two adjacent plates on one side and the water from the second branch 20 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 circuit, even if the storage of the thermal energy was only caused by the removal 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, which typically involves drawing a lot of hot water 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 drawing water 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, which were previously described in connection with Figure 3, are also provided in the hot water station in Figures 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. The thermal insulation 61 can thus keep the hot water warm enough for use for up to 24 hours. In this embodiment, a 100-watt heating element 66 is also provided, with which the cooled water in the small hot water tank can be heated to 60 degrees Celsius after a long period of inactivity.

The embodiment described in connection with Figures 4 to 6 has the same advantages as the embodiment described in connection with Figure 3. In both hot water branches 10, 20 the output volume is below a predetermined value, in particular it is equal to or less than three liters. The discharge capacity is higher at more than 20 liters/min by supplying the extraction stations 71, 72, 73, 74 through two hot water branches 10, 20. The drinking water supply is more powerful, although less energy is required. Planning and implementation are also simplified because only one installation path is provided instead of two if two heating stations 50 were provided for the two hot water branches. Even if the heating station has the same or similar power consumption of 100 W as in the previous 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 connection 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 this embodiment, the components are optimized for operation with a heat pump. The drinking water heater 1 has a very high efficiency because there is no turbulence or mixing caused by hot water flowing back into the heat storage tank 3, as would be the case with a circulation line. The circulation line-free pipe system 9 leads to a high efficiency of the hot water system, because the efficiency of the heat pump depends on the temperature gradient.

The features specified above and in the claims as well as those shown in the figures are applicable both individually and in different

Combination can be implemented advantageously. The invention is not limited to the described embodiments, but can be modified in many ways within the scope of expert knowledge.

Reference symbol

Drinking water heater

3 hot water tanks

9 Pipeline system

11 Supply line

13 Distribution line

15 heat exchangers

17 Bypass valve

19 Cold water pipe

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 tanks

62 Thermal insulation

64 heat exchangers

66 Heating element

68 Phase change material

70, 71 , 72, 73, 74 Removal station

80 mini heat storage units

Claims

Expectations:

1. Hot water system with

- a drinking water heater (1) with a hot water tank (3),

- a removal station (70, 71, 72, 73, 74),

- a circulation line-free line system (9) between the drinking water heater (1) and the extraction station (70, 71, 72, 73, 74), which is designed such that heated drinking water flows from the drinking water heater (1) along a line path in the line system (9) to the extraction station (70, 71, 72, 73, 74), wherein a pressure in the line system and a pipe cross-section of the line system depend on a length of the line path, so that a line volume of the line path is less than or equal to a predetermined maximum line volume, and wherein the line path comprises a first section and a second section and between the first section and the second section a hot water station (50, 51, 52) is provided in the line system (9), which is designed to heat and/or store the drinking water.

2. Hot water system according to claim 1, wherein a first pressure in the first section and a first pipe cross-section of the first section depend on a length of the first section, so that the sum of a first line volume of the first section and a second line volume of the second section is less than or equal to the predetermined maximum line volume.

3. Hot water system according to claim 1 or 2, wherein one or more further extraction stations (70, 71, 72, 73, 74) are connected to the hot water station (50, 51, 52), and wherein the line volumes in each line path between the drinking water heater (1) and the further extraction station (70, 71, 72, 73, 74) or one of the further extraction stations (70, 71, 72, 73, 74) are less than or equal to the predetermined maximum line volume, in particular less than or equal to three liters.

4. Hot water system according to one of the preceding claims, wherein the first pipe cross-section has a diameter which is less than or equal to 11.6 mm, in particular less than or equal to 9.6 mm, in particular less than or equal to 8.4 mm and in particular less than or equal to 7 mm, if the length of the first section is a maximum of 25 m or a maximum of 35 m or a maximum of 45 m or a maximum of 65 m, and wherein the first pressure is greater than or equal to 0.71 bar, in particular greater than or equal to 2.47 bar, in particular greater than or equal to 6.01 bar and in particular greater than or equal to 20.81 bar, if the length of the first section is a maximum of 25 m or a maximum of 35 m or a maximum of 45 m or a maximum of 65 m.

5. Hot water system according to one of the preceding claims, wherein a pressure booster (23) is connected upstream of the drinking water heater (1).

6. Hot water system according to one of the preceding claims, wherein the hot water station (50, 51, 52) comprises a pressure regulator (31) or a pressure regulator (31) is connected upstream thereof.

7. Hot water system according to one of the preceding claims, wherein the hot water station (50, 51, 52) comprises a continuous flow heater (33) which is designed to heat water.

8. Hot water system according to one of the preceding claims, wherein the hot water station (50, 51, 52) comprises a small hot water tank (60).

9. Hot water system according to claim 8,

- wherein the small hot water tank (60) has a thermal insulation (62),

- and/or wherein the small hot water tank (60) is designed to heat water stored therein,

- and/or wherein the small hot water tank (60) has a heat exchanger (64) with phase change material (68).

10. Hot water system according to claim 9,

- wherein the heat exchanger (64) of the small hot water storage tank (60) has two separate drinking water primary circuits (10, 20) and a secondary circuit which comprises the phase change material (68).

11. Hot water system according to one of the preceding claims, wherein the hot water station (50, 51, 52) comprises a bypass valve (17) which switches to an open state as soon as hot water with a predetermined minimum temperature is available on the inlet side of the hot water station (50, 51, 52).

12. Hot water system according to one of claims 8 to 11, wherein a small heat accumulator (80) with a lower water storage capacity than a water storage capacity of the small hot water storage tank (60) is provided at at least one of the extraction stations (70, 71, 72, 73, 74).

13. Hot water system according to one of the preceding claims, wherein the pipe system (9) is free of fresh water stations.

14. Hot water system according to one of the preceding claims, which is a small system according to the German Drinking Water Ordinance, in particular DVGW Worksheet W 551.

15. Hot water system according to one of the preceding claims, whose drinking water heater (1) is coupled to a heat pump (19) which is designed to heat water in the drinking water heater (1).