Hot water system

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

[0001] HOT WATER SYSTEM

[0002] The invention relates to a hot water system.

[0003] A hot water system comprises a drinking water heater with a hot water tank and one or more draw-off points to which hot water flows from the drinking water heater through a pipe system.

[0004] Long pipe runs mean that providing hot water from the drinking water heater to the draw-off points takes considerable time. If no water is drawn, the water stagnates in the pipe system and cools down. Standing water in the pipe system for an extended period can lead to hygiene problems if waterborne bacteria, such as Legionella, multiply rapidly.

[0005] In conventional piping systems with long pipe runs, a circulation pipe is provided for reasons of comfort. This ensures that hot water circulates in the pipe system and thus always flows past or close to the draw-off points, so that hot water is available at the draw-off points immediately or after a short time. If the circulating hot water is at a sufficiently high temperature, water bacteria are killed, thus reducing hygiene problems. However, a pump is required for the circulation, which consumes the same energy as heating the circulating hot water. Heating the constantly circulating drinking water to approximately 60 degrees Celsius, with possibly only a short draw-off time during which water is drawn, is complex and involves thermal losses and electrical consumption. Furthermore, in a system with a heat pump for heating, the greatest losses due to heat pumps occur at approximately 60 degrees Celsius.The circulating drinking water also causes the drinking water stored in the hot water tank to mix, which negatively impacts the performance of the heat pump. These effects lead to a loss of approximately 50% of the energy used.

[0006] 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 control strips are mandatory for hygiene reasons in accordance with legal requirements in Germany.

[0007] According to the German Drinking Water Ordinance, a distinction is made between small and large systems. For small systems, the volume in the pipes between the drinking water heater and the draw-off points is less than or equal to 3 liters. Furthermore, the capacity of the drinking water heater's hot water tank is less than or equal to 400 liters. If these requirements are not met, the system is considered a large system, unless the hot water system is located in a single- or two-family home. For large systems in public or commercial buildings, including rental apartments, an annual microbiological drinking water test must be conducted. This testing requirement does not apply to small systems.

[0008] CH 100 898 A shows a hot water supply system in which insulated hot water reservoirs are provided between the water heater and the draw-off stations.

[0009] 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.

[0010] DE 10 2011 122 639 A1 shows a hot water supply in which a continuous flow heater between the water heater and the draw-off 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.

[0011] AT 374 269 B shows a hot water supply system in which a distributor is provided between the water heater and the draw-off points. When the temperature falls below a minimum, the water is piped through a branch pipe where it is heated.

[0012] DE 10 2014 225 693 A1 shows a hot water supply system in which a distributor is provided between the water heater and the draw-off points. A parallel second line with an auxiliary heat source can provide additional hot water as needed.

[0013] DE 295 03 746 U1 shows a hot water generator that stores latent heat.

[0014] The task is to provide an improved hot water system.

[0015] The problem is solved by a hot water system having the features of claim 1.

[0016] The hot water system is provided with a drinking water heater with a hot water tank, a withdrawal station, and a circulation-free pipe system between the drinking water heater and the withdrawal station, which is designed to flow heated drinking water 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, such 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.

[0017] Storage is particularly intended for heated drinking water, whether from the drinking water heater or heated by the hot water station.

[0018] The hot water system is piping-free; that is, there is no circulation line through which hot water constantly circulates. This saves energy. Due to the lack of circulation, a system with a heat pump saves approximately 50% of energy compared to a system with a circulation line, as the effort required to heat and circulate the drinking water is eliminated. Furthermore, the heat pump can be operated more efficiently due to the lack of mixing in the hot water tank. Advantageously, there is also no fresh water station in the piping system, which uses heat from a water-based central heating system for instantaneous water heating, so the effort required is minimal compared to a conventional hot water system.

[0019] The drinking water heater heats the drinking water supplied at the inlet 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, especially 50 to 60 degrees Celsius, and can be drawn off at the draw-off point. Multiple draw-off points can be provided in the hot water system. Examples of draw-off points include faucets and showers.

[0020] 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 draw-off point. The dimensioning of pressure and pipe cross-section, particularly 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 draw-off point. The maximum pipe volume is low for hygiene reasons. The maximum pipe volume is advantageously in accordance with legal or structural specifications. A small system as defined by the German Drinking Water Ordinance, in particular DVGW Worksheet W 551, has a maximum pipe volume of 3 liters, meaning that the mandatory annual microbiological drinking water testing is not required for such a system.

[0021] In comparison to a conventional hot water system, in which the length of pipes with a given pipe cross-section is limited by the given 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 given 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 associated with a higher flow velocity, so that there is less deposit in the pipes and bacterial growth is inhibited. The length of the pipe route between the drinking water heater and the draw-off station is longer than in conventional hot water systems without a circulation line.The length of the cable 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.

[0022] Between the first and second sections, a hot water station is provided in the pipe system through which the drinking water flows. The hot water station is designed to heat and / or store hot water provided at the inlet. If the previously heated drinking water has been standing in the pipe for an extended period because no hot water was drawn, the water, which has since cooled down, can be reheated by the hot water station before being drawn. 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 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. The preheating and / or intermediate storage provided by the hot water station improves comfort, as hot water is available at the draw-off point more quickly than if no hot water station were provided and the cold water had to drain away through the pipes 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 draw-off points, which is formed by distribution lines between the hot water station and the draw-off points. The first section of the pipe route is the supply line. The second section is the distribution line between the hot water station and the draw-off point.The hot water station has connections for the distribution line and thus supplies 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, one for the kitchen and one for the bathroom.

[0023] 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 split into a first maximum volume for the first section and a second maximum volume for the second section. The first pressure in the first section and the first pipe cross-section of the first section depend on the length of the first section, so that the pipe volume of the first section is less than or equal to the first maximum volume. Furthermore, the pipe volume of the second section must be less than or equal to the second maximum volume. This requirement must be met for the distribution line of the second section.

[0024] Advantageously, the first pressure differs from the second pressure of the second section. To bridge 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 design, a pressure booster is installed upstream of the drinking water heater 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.

[0025] In one embodiment, one or more additional withdrawal stations are connected to the hot water station, with the pipe volumes in each pipe route between the drinking water heater and the additional withdrawal station or one of the additional withdrawal stations being less than or equal to the specified maximum pipe volume. Thus, the pipe volume for the pipe route to each withdrawal station is less than or equal to the maximum pipe volume. Typically, the pipe route to the withdrawal station furthest from the drinking water heater has the largest pipe volume, so as a rule of thumb, it is sufficient for the pipe volume to be less than or equal to the maximum pipe volume when dimensioning. Additional withdrawal stations can be provided between the furthest withdrawal station and the drinking water heater, and are advantageously connected to one another by a loop-through installation.The following shows examples of inner pipe diameters and pressures for specified maximum pipe lengths. For example, in a 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 of 65 m to the hot water station. This maximum pipe length significantly exceeds the pipe length in a conventional hot water system without a circulation line. In the aforementioned examples, the pipes can have an outer diameter of 16 mm to facilitate assembly and installation by ensuring uniform pipe outer dimensions.

[0026] In one version, the hot water station includes an instantaneous water heater designed to heat water during a discharge time until hot water from the drinking water heater reaches the hot water station. This increases comfort in long supply lines, as hot water is immediately available at the draw-off point, even if the water in the line is already cold at the time of draw-off.

[0027] In one version, the hot water station includes a bypass valve that bypasses the instantaneous water heater as soon as hot water at a specified temperature is available on the inlet side of the hot water station. Hot water at a specified minimum temperature bypasses the instantaneous water heater.

[0028] Nevertheless, the hot water station can be provided with an additional heater that additionally heats the hot water from the drinking water heater.

[0029] In one version, the hot water station includes a small hot water tank with a storage capacity lower than that of the hot water tank of the domestic hot water heater. In this version, the hot water station acts as a decentralized buffer, providing hot water closer to the draw-off points, thus shortening the time until hot water is available at the draw-off points.

[0030] 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. Additionally or alternatively, the small hot water tank is designed to heat water stored therein. This allows the cooled water to be reheated during extended downtimes in which no water has been drawn from the small hot water tank and hot water has been added 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.

[0031] 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 through the primary circuit of the heat exchanger. The secondary circuit contains the phase change material, which stores a large portion of the thermal energy supplied to it from the primary circuit in the form of latent heat (e.g., 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, especially when hot water is flowing through, sufficient hot water is available at the draw-off point. The phase change material can, for example, be wax-like and liquefy when heated.If no use has been made for an extended period, the latent heat stored in the phase-change material serves to warm the cooling water to counteract the cooling process. The phase-change material solidifies again and releases the released thermal energy to the stored water. Electrical heating can support the provision of hot water by reheating the stored water when it cools below a predetermined threshold, if necessary several times, to counteract the cooling process, ensuring that hot water is always available in the small hot water tank for use. The energy required for this is significantly less than if no phase-change material were used.

[0032] In one design, the heat exchanger of the small hot water tank has two separate primary drinking water circuits and a secondary circuit containing 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 kitchen of an apartment. The pipes of the two branches are separate from each other. No water exchange takes place. However, thermal coupling takes place 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. In other words: heat exchange takes place from each of the two separate primary circuits with the secondary circuit, without any water exchange taking place between the two primary circuits.More than two primary circuits can also be provided, which are thermally coupled in this way.

[0033] For example, a long shower with hot water drawn from one hot water branch can cause thermal energy to be stored, which is then released into the other hot water branch for water drawn in the kitchen. This design offers an additional increase in efficiency, because drawing hot water from one of the primary circuits thermally charges the phase-change material acting as a storage device, and this charged energy storage is also available to the other primary circuit.

[0034] The water tank can also be bypassed with a bypass valve if sufficient hot water has already been stored. However, a regular flow of hot water also benefits the regular recharging of the phase change material, which acts as a storage tank.

[0035] In one version, the drinking water heater is coupled to a heat pump, so that the heat pump heats potable cold water to hot water. The piping system, which is free of circulation lines, results in a high level of efficiency for the hot water system, as the efficiency of the heat pump depends on the temperature gradient. This gradient is significantly higher between the hot water in the hot water tank 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 is avoided, thus reducing the temperature gradient. Some examples are explained in more detail below using the drawings. They show:

[0036] Figure 1 shows schematically an embodiment of a hot water system,

[0037] Figure 2 shows schematically another embodiment of a hot water system,

[0038] Figure 3 schematically shows another embodiment of a hot water system,

[0039] Figure 4 schematically shows another embodiment of a hot water system,

[0040] Figure 5 schematically shows details of the embodiment of a hot water system, and

[0041] Figure 6 schematically shows further details of the embodiment of a hot water system.

[0042] In the figures, identical or functionally equivalent components are provided with the same reference numerals.

[0043] Figure 1 schematically shows an embodiment of a hot water system with a drinking water heater 1 with hot water tank 3 and, for example, two hot water stations 51, 52 and three withdrawal 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 withdrawal. The heating is carried out, for example, by a heat exchanger 15. Between the drinking water heater 1 and the withdrawal stations 71, 72, 73, a circulation-line-free pipe system 9 is provided, which is designed so that hot water flows from the hot water tank 3 of the drinking water heater 1 to the withdrawal stations 71, 72, 73. The hot water can be withdrawn at the withdrawal stations 71, 72, 73, which can be, for example, a shower or a faucet.The hot water stations 51, 52, which serve as hot water transfer points, are connected to the drinking water heater 1 via supply lines 11. Distribution lines 13 extend from the hot water stations 51, 52 to the draw-off points 71, 72, 73. Several connections can be provided at the hot water stations 51, 52 for distribution lines 13 to draw-off stations 71, 72, 73. Several draw-off stations can advantageously be installed in series, so that the distribution line to the most distant draw-off station is looped through further draw-off stations.

[0044] Between the drinking water heater 1 and a first draw-off 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 draw-off 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.

[0045] Between the drinking water heater 1 and a second and third draw-off station 72, 73, the hot water flows via the second hot water station 52. A pipe route between the drinking water heater 1 and the second draw-off 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 draw-off 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 draw-off station 73 runs via the second hot water station 52 and the second draw-off 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 draw-off station 73.The pipe volume in the pipes of the line route is less than the specified maximum pipe volume. This line route leads to the furthest withdrawal station 73 and extends beyond the previously described line route to the second withdrawal station 72. It has the largest pipe volume of all three lines. The pipe volume in each of the lines is less than the specified maximum pipe volume of 3 liters.

[0046] The hot water system is a small system, with the pipe volume of each pipe being less than 3 liters. Furthermore, the volume of water tank 3 is less than or equal to 400 liters.

[0047] Such a hot water system with two hot water stations 51, 52 can, for example, be provided for two small apartments, each with a hot water station 51, 52. For a two-person apartment, one hot water station is sufficient for the draw-off points in the kitchen and bathroom. 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 draw-off points. 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 the inner pipe diameter, 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 routes downstream of the heating stations, and 2.4 liters are provided for the pipe 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 sections and 2.5 liters for the first sections.

[0048] The hot water system does not require a circulation line or a fresh water station. This results in high cost-effectiveness for both investment and operation. The pipe run can be very long, allowing, for example, a large building to be supplied or a drinking water heater 1 to be operated outside the house.

[0049] Figure 2 schematically shows another embodiment of a hot water system comprising a drinking water heater 1 with a hot water tank 3, a hot water station 50, and a draw-off station 70. A house connection 21 is provided inside the house, at which potable 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 a backflow preventer, 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.

[0050] The drinking water heater 1 comprises a hot water tank 3, into which the potable cold water flows, and is designed to heat the potable cold water through a heat exchanger 15 and provide it as potable hot water in the hot water tank 3. The drinking water heater 1 provides the hot water at a drinking water outlet at an increased pressure, for example, 9 bar. Typically, the hot water in the hot water tank 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.

[0051] The hot water can flow to the hot water station 50 via a pipe system 9 without circulation pipes and having a supply line 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 an extended period of time cools down. The hot water station 50 comprises a pressure regulator 31, which is designed in particular to reduce the pressure, and an electric instantaneous water heater 33. One or more withdrawal stations 70 can be connected to the hot water station 50 via distribution lines 13. In this exemplary embodiment, a withdrawal 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 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 bridges the instantaneous water heater 33 as soon as hot water is available at the instantaneous water heater 33.

[0052] Since the piping system 9 does not include a circulation line, the hot water from the hot water tank 3 is only available at the draw-off station 70 after the discharge time, when the cold water has drained from the piping system 9. In the meantime, hot water is provided by the instantaneous water heater 33, which heats the water flowing out of the supply line 11 until the line is hot. 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 for continuous bypassing of the instantaneous water heater starting at a water temperature of 45 degrees Celsius.

[0053] 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.

[0054] Even in the event of an emergency, i.e. if the hot water tank 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.

[0055] 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 An internal thread connection is provided. The piping is available in one design as a raw or pre-assembled set. Alternatively, it can be pre-installed on the hot water station 50 upon delivery.

[0056] In one exemplary embodiment, such a hot water station is a rectangular device with an exemplary size of 540 x 300 x 82 mm. It weighs approximately 9 kg, making it easy to mount on a wall. 1" internal thread connections are provided. A typical draw-off rate is 10 l / min. A 9 kW connection rating 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.

[0057] In one embodiment, the operating temperature of the hot water station 50 is 50 degrees Celsius or 55 degrees Celsius, thus reducing limescale buildup. The operating pressure of the hot water station 50 is permanently 6 bar, with pressure surges of up to 10 bar possible. The hot water station 50 is also advantageously designed to electrically reheat the supplied water, so that the hot water from the drinking water heater 1, which is at 50 degrees Celsius, is reheated to 60 degrees Celsius in the hot water station. This increases comfort.

[0058] All water-bearing 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.

[0059] The hot water system is dimensioned to be a small system according to DVGW Worksheet W551. This allows the hot water system to be operated at economical temperatures without the need for inspection.

[0060] The maximum pipe length between the domestic hot water heater and the transfer point is 65 m, with a maximum pipe volume of 2.4 liters in the 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 draw-off 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.

[0061] The following lists pipe and pressure combinations for various pipe lengths between the drinking water heater and the hot water transfer point, which also ensure that 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 line between the drinking water heater and the hot water transfer point. The pipes for the piping system can be made of, for example, polyethylene with increased temperature resistance, or PE-RT for short.

[0062] With 7 x 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 pipe length of 65 m can be achieved. The pressure is 20.81 bar, allowing a flow rate of 10 l / min of unmixed hot water to be achieved. The system requires a pressure regulator 31 and, to achieve the pressure in the supply line 11, a pressure booster 23, as shown in Figure 2. These components are optional for other dimensions.

[0063] With 8.4 x 3.8 mm pipes, which have an outer diameter of 16 mm, a maximum pipe length of 45 m can be achieved. The pressure is 6.01 bar, allowing a flow rate of 10 l / min of unmixed hot water to be achieved. The system requires a pressure booster 23. With 9.6 x 3.2 mm pipes, which have an outer diameter of 16 mm, a maximum pipe length of 35 m can be achieved. The pressure is 2.47 bar, allowing a flow rate of 10 l / min of unmixed hot water to be achieved. The system requires a pressure booster 23 at pressures below 6 bar.

[0064] With 11.6 x 2.2 mm pipes with an outer diameter of 16 mm, a maximum pipe length of 25 m can be achieved. The pressure is 0.71 bar, allowing a flow rate of 10 l / min of unmixed hot water to be achieved.

[0065] Figure 3 schematically shows another embodiment of a hot water system. It comprises a drinking water heater 1 with a hot water tank 3, a hot water station 50, and two draw-off 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 draw-off. Heating is achieved, 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 range from 20 to 51 degrees Celsius due to cooling if no water has been drawn for an extended period.

[0066] Between the drinking water heater 1 and the withdrawal stations 71, 72, a circulation-free pipe system 9 is provided, through which hot water flows from the hot water tank 3 to the withdrawal 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 withdrawal points 71, 72. The withdrawal points 71, 72 are installed in series, so that the distribution line 13 is looped through the first withdrawal station 71 to the furthest second withdrawal station 72. The cold water line 19 shown in the drawing is connected in a similar manner.

[0067] 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 volume in the pipes of the line route 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 most distant extraction point 72 is a maximum of 0.5 liters.

[0068] 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 tank 60. In this embodiment, a bypass valve can also 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, ensuring regular water exchange.

[0069] 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 smaller 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 must be smaller than a maximum volume. However, the total volume of all water tanks in the system must be smaller than a maximum storage volume to be exempt from the inspection requirement. According to the Drinking Water Ordinance, the maximum storage volume is smaller than 400 liters. The small hot water tank 60 has thermal insulation 62 that slows down the cooling of stored hot water. The small hot water tank 60 is also designed to heat the water electrically, so that hot drinking water is available in the small hot water tank 60 even if no water has been drawn off for an extended period.For example, one embodiment provides for heating to 60 degrees Celsius after a prolonged period of inactivity. Heating can occur, for example, as soon as the temperature of the stored water has dropped below a predetermined threshold, until the temperature of 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 power output of 100 watts.

[0070] 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 portion of the thermal energy supplied to it from the primary circuit in the form of latent heat (particularly 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. Flowing and / or heated hot water causes a phase change of the phase change material and stores part of the thermal energy of the hot water.Nevertheless, even after warm water flows through the system, some of whose thermal energy has been used for the phase change, sufficient warm water is provided at the tap. If no water has been drawn for an extended period, the thermal energy stored in the phase change material slows the cooling of the stored water. The phase change material solidifies, and the thermal energy released is transferred to the stored water, heating it.

[0071] For example, water from the supply line at approximately 50 degrees Celsius can trigger 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 at the withdrawal stations 71, 72.

[0072] 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 draw-off points 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 drawn off without reheating. The hot water station 50 can provide hot water at the draw-off points 71, 72 after just 8 to 15 seconds. Furthermore, the lower pressure loss of the plate heat exchanger enables a discharge rate of 15 liters / min. This means that the discharge rate and the hot water delivery time are superior to the previous embodiment with a continuous flow heater.

[0073] The hot water station 50 with a small hot water tank 60 has almost the same dimensions as a hot water station 50 with an instantaneous water heater 33. However, due to the thermal insulation 62, the depth is usually greater. The connections and fittings are the same.

[0074] The removal stations 71, 72 have in this embodiment of a

[0075] Each system has a small heat storage unit 80 in which hot water can be stored in the immediate vicinity of the outlet from the draw-off stations 71, 72. The small heat storage unit 80 is a compact, small heat storage unit, designed, for example, as an under-counter heat storage unit. It can typically store approximately 0.5 liters of water. The optional small heat storage unit 80 increases comfort in terms of hot water supply time, reducing it to less than 8 seconds. 5 seconds is a typical value.

[0076] The miniature heat storage unit 80 includes thermal insulation to slow the cooling of the water. Advantageously, the miniature heat storage unit 80 also includes a heating element and a heat exchanger with phase-change material, the operation of which has been described above. The electrical power consumption is in the range of 50 watts.

[0077] The storage volume of the 80-gauge micro-heat storage units is also not included in the pipe volume, which must be less than a maximum volume to qualify as a small system. However, the storage volume of the 80-gauge micro-heat storage units does count toward the total volume of all water storage units in the system, which must be less than a maximum storage volume to be exempt from the inspection requirement.

[0078] 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.

[0079] 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 hot water is available at the draw-off points than a conventional system. The hot water station with small hot water storage tank and the small heat storage tanks have very low electrical energy consumption, especially compared 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 is almost negligible compared 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 many residential units.Due to the low energy consumption, with an exemplary power consumption of 50 to 100 watts, the total grid connection power is significantly lower compared to a conventional system, but also compared to the previous example. With multiple hot water stations 50, a simultaneity lock to limit the number of simultaneously operated hot water stations 50 is no longer required. Smaller cable cross-sections can be used for the power supply. Additional transformer stations are not required. This overall lower power supply effort also leads to less planning effort for the system, and in particular the electrical supply.

[0080] Figure 4 schematically shows another embodiment of a hot water system. The following description focuses on differences from the previous embodiment shown in Figure 3.

[0081] 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 second withdrawal station 71, 72 in the first water branch 10, and, on the other hand, hot water from the drinking water heater 1 is conducted to a third and fourth withdrawal 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 a looped-through installation and miniature heat storage units 80 as in the previous exemplary embodiment.

[0082] 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 designed for two hot water branches 10, 20, it has duplicate connections for their distribution lines 13. The housing dimensions are also larger than in the previous embodiment, as it stores more water to supply two branches 10, 20.

[0083] In each of the branches 10, 20, the pipe volume in the pipes of the pipe route is less than or equal to the specified maximum pipe volume of 3 liters.

[0084] 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,

[0085] 131 of the first branch 10 and with inflowing and outflowing water 112,

[0086] 132 of the second branch 20. There is no mixing of the drinking water between branches 10, 20. There is also no mixing in the hot water station 50. In addition to separate distribution lines 13, the hot water branches 10, 20 also have separate supply lines 11 that run between the drinking water heater 1 and the hot water station 50.

[0087] The secondary circuit of heat exchanger 64 comprises phase-change material and interacts with both primary circuits, allowing thermal coupling through the secondary circuit. Heat from each of the primary circuits can be stored in the secondary circuit and released from the secondary circuit to each of the primary circuits. This allows the phase-change material to be charged by one primary circuit, and then the stored thermal energy can be released to the other primary circuit.

[0088] Figure 6 schematically shows a 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 alternatingly 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 alternatingly, 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 extraction in one of the branches 10, 20.Nevertheless, both primary circuits can charge the phase change material 68.

[0089] For example, a shower in the first branch 10, during which a large amount 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 withdrawal in the kitchen in the second branch 20, but also, for example, for washing hands in the bathroom 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 for 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 its cooling. The thermal insulation 61 can thus keep the hot water sufficiently warm for withdrawal 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 longer period of inactivity.

[0090] 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 due to the supply of the extraction stations 71, 72, 73, 74 by 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 heat 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.

[0091] 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 such an embodiment, the components are optimized for operation with a heat pump. The drinking water heater 1 is very efficient because there is no turbulence or mixing caused by returning hot water in 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, since the efficiency of the heat pump depends on the temperature gradient.

[0092] The features stated above and in the claims as well as those shown in the figures are applicable both individually and in various

[0093] The invention is not limited to the described embodiments, but can be modified in many ways within the scope of expert knowledge.

[0094] Reference symbol

[0095] Drinking water heater

[0096] 3 hot water tanks

[0097] 9 Pipeline system

[0098] 11 Supply line

[0099] 13 Distribution line

[0100] 15 heat exchangers

[0101] 17 Bypass valve

[0102] 19 Cold water pipe

[0103] 21 House connection

[0104] 23 pressure boosters

[0105] 31 pressure regulators

[0106] 33 instantaneous water heaters

[0107] 49 heat pump

[0108] 50, 51 , 52 Hot water station

[0109] 60 small hot water tanks

[0110] 62 Thermal insulation

[0111] 64 heat exchangers

[0112] 66 Heating element

[0113] 68 Phase change material

[0114] 70, 71, 72, 73, 74 withdrawal station

[0115] 80 micro heat storage units

Claims

Claims:

1. Hot water system with - a drinking water heater (1) with a hot water tank (3), - a withdrawal station (70, 71, 72, 73, 74), - a circulation line-free line system (9) between the drinking water heater (1) and the withdrawal 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 withdrawal 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 pipe volume of the first section and a second pipe volume of the second section is less than or equal to the predetermined maximum pipe 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 withdrawal station (70, 71, 72, 73, 74) or one of the further withdrawal 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 of it.

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 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 withdrawal 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).

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