Highly efficient instantaneous water heater, equipped with two independent temperature controls to bring the domestic water to a precisely preset temperature

Abstract

The present invention relates to a method for heating domestic water using the instantaneous flow principle, wherein the desired domestic water temperature can be precisely specified, but the temperature of the heating-side medium may deviate significantly from the desired domestic water temperature. This object is achieved by a method and a system according to the invention, wherein cold domestic water is heated by means of a heat exchanger (1) using the countercurrent principle and a temperature controller (3) and (5a) are installed in both the heating-side primary circuit (2a, 8) and the secondary-side domestic water circuit (12b, 11), wherein the first temperature controller (3) reduces the temperature of the storage medium in the heat accumulator (6) from a high level to a lower level using a thermostatic mixing valve (2), and the second temperature controller (5a) brings the domestic water to the domestic water temperature precisely preset by the user using the charging pump (4).

Description

[0001] The present invention relates to a method for heating domestic water in a heat exchanger (1) using the flow-through principle, wherein the desired domestic water temperature, measured at the temperature sensor (5), can be precisely specified, but the temperature of the heating-side medium in the heat accumulator (6) can deviate significantly from the desired domestic water temperature.

[0002] This object is achieved by a method and a system according to the invention, wherein a storage medium, such as heating water, is first heated to a high temperature by means of a boiler, a wood-burning boiler, a solar thermal system, an electric heating system via photovoltaics, or any other heating system, and is then temporarily stored in a heat storage device (6), which generally consists of a buffer tank or stratified storage tank. When a consumer draws hot water from a consumption point in the building, cold domestic water initially flows through the cold water pipe (12), through the flow meter (12a), and through the pipe (12b) into the heat exchanger (1), flows through the heat exchanger, and exits again as heated hot water in the hot water pipe (11), before being fed to the open tap point (e.g., shower, washbasin, bathtub, kitchen sink, etc.).) in the building, with normal domestic water temperatures being between 45°C and 55°C.

[0003] The flow meter (12a) detects the water flow in the cold water line (12) and, via the temperature control (5a), sets the charging pump (4) in motion. The charging pump (4) immediately pumps hot storage medium from the heat storage tank (6) via the supply lines (7, 2b, and 2a) into the heat exchanger (1). The storage medium is pumped through the heat exchanger (1) in the countercurrent to the flow of the domestic hot water and returns to the heat storage tank via the return lines (8 and 10). The temperature sensor (5), which is located in an immersion sleeve (5b) in the heat exchanger (1), continuously measures the temperature of the outflowing hot water, and the temperature control (5a) continuously regulates the speed of the charging pump (4) so ​​that a domestic hot water temperature set by the consumer, for example, 50°C, can be precisely maintained.The set domestic water temperature should only be allowed to fluctuate minimally so that a consumer does not notice any temperature fluctuations in the domestic water at their tap. However, if the storage medium in the heat storage tank (6) is heated to up to 95°C by the aforementioned boilers, wood heating systems, solar thermal systems or electric heating, this will result in significant fluctuations in the domestic water temperature in practice, as the control system (5a) can no longer regulate the charging pump (4) precisely, or the charging pump (4) would have to run extremely slowly, which in practice leads to significant temperature fluctuations in the hot water pipe (11) in commercially available fresh water stations. In practice, this can result in temperature fluctuations in the domestic water of up to 5°C or even more. These temperature fluctuations can be very unpleasant for the consumer in the shower and often lead to complaints to the responsible plumbers or heating engineers.The inventive arrangement of an upstream second temperature control (3) and a 3-way thermostatic mixer (2) allows the above-described temperature fluctuations to be completely avoided. The hot storage medium is pumped by the charging pump (4) from the heat storage tank (6) through the flow line (7) into the lower inlet of the 3-way thermostatic mixer (2) and then reaches the heat exchanger (1) via the flow lines (2b and 2a). The cold water flowing countercurrently in the heat exchanger (1) significantly cools the storage medium, and it returns to the heat storage tank (6) via the return lines (8) and (10). If the temperature of the storage medium is, for example, between 60°C and 95°C, the temperature control (3) is activated and directs the storage medium, which has already been cooled by the heat exchanger (1), into the third connection of the 3-way thermostatic mixer (2) via the return line (8 and 9).This means that the storage medium from the flow line (7), which is too hot, is mixed with the cool medium from the return line (9) within the 3-way thermostatic mixer (2) in such a way that the storage medium can be cooled to, for example, 60°C. Only storage medium at, for example, 60°C flows into the heat exchanger (1) via the flow lines (2b and 2a), whereby the temperature control (5a) can then easily bring the hot water to the 50°C desired by the user. The heat storage tanks (6) are often called buffer tanks or stratified storage tanks in practice. The maximum permissible temperature of the heat storage tanks (6) is usually limited by the manufacturer to a maximum of 95°C. In practice, the control system (3) can operate at a maximum operating temperature of up to 110°C, so that the storage medium can also be 110°C.

[0004] Various fresh water stations, hot water stations, or domestic water dispensers are available from many manufacturers. These units heat cold fresh water using a hot storage medium, usually heating water, in a heat exchanger using the countercurrent principle. The cold water is then pumped to various points of use, such as sinks, showers, bathtubs, kitchen sinks, etc. These commercially available fresh water stations, hot water stations, or domestic water dispensers all have the advantage of heating the domestic water at the exact moment it is needed. This means there is hardly any heat loss or idle water losses, hardly any stagnant water, and, due to the small volume of the heat exchangers, virtually no Legionella formation. According to current German regulations (Drinking Water Ordinance, VDI 6023, etc.), the system is designed to meet the highest standards of hygiene.), the domestic water temperature must be permanently kept at a minimum of 60°C when using conventional domestic water storage tanks (boilers), whereas with fresh water stations based on the flow principle the domestic water temperature can be reduced to 50°C, which is a huge advantage in terms of energy savings. The consumer always has fresh, hygienic warm water at 50°C. The disadvantage of these commercially available fresh water stations, however, is that if the storage medium (heating water) is too hot and can be well over 60°C, they cannot regulate the domestic water exactly to 50°C due to control technology. This can lead to the domestic water temperature at the taps fluctuating considerably, and if the storage medium is too hot the heat exchangers on the domestic water side can quickly become calcified.

[0005] In practice, however, the storage medium (heating water) in the buffer storage tanks used is often heated to well over 60°C, even up to 95°C, by solar thermal systems, log boilers, wood gasification boilers, pellet boilers, fireplace stoves with water tanks or power to heat systems (electric heating elements coupled with photovoltaic systems).

[0006] Under these extreme conditions, commercially available fresh water stations can heat cold fresh water at 10°C to approximately 50°C to 60°C, but due to the hot storage media, which can reach temperatures of up to 95°C, they experience significant temperature fluctuations in the hot water. Experience has shown that these temperature fluctuations can exceed 5 Kelvin. These fluctuations are very unpleasant for the user in the shower and often lead to complaints with the plumber or heating engineer. Therefore, commercially available fresh water stations are generally only approved by the manufacturer for storage media or heating water with a maximum temperature of 60°C.

[0007] The following publications were used for further assessment: DE 102019107179A1 Method for supplying at least one water intake point with cold and hot water DE 202016007060U1 Mechanical / powerless pump for fresh water station EP 2226571A1 Arrangement and method for heating drinking water for a consumption or tapping point EP 2366955A2 Domestic water preheating device for an instantaneous water heater EP1798486A2 Heating or domestic hot water storage tank with at least two heat sources EP 2369243 B1 20180711 Method for heating drinking water Fresh water station with integrated electronic instantaneous water heater EP 0356371A1 Water heating system

[0008] The inventions proposed in the documents do not all have the temperature controls 3 and 5a described in the present invention according to claim 1.

[0009] The present invention avoids the undesirable temperature fluctuations at the consumer taps by means of the two temperature controls (3) and (5a) connected in series and operating independently of one another according to claim 1.

[0010] The following figures illustrate the method and system according to the invention and show further features and advantages. Herein: Fig. 1: a schematic representation of an advantageous embodiment of the method or system according to the invention and Fig. 2: an alternative schematic representation of the system according to the invention

[0011] Fig. 1 shows the schematic structure of an advantageous embodiment of the system according to the invention, wherein the storage medium is brought from a high temperature to a lower temperature by means of a mechanical 3-way thermostatic mixer (2).

[0012] The storage medium, which usually consists of conventional heating water, is heated by various heating devices such as oil boilers, gas boilers, pellet boilers, wood chip boilers, high-temperature heat pumps, solar thermal systems, electric heating inserts, etc., and temporarily stored in the heat storage unit (6). Depending on the manufacturer, the heat storage units (6) can be heated to a temperature of up to 95°C. There are even special storage units that can be heated above 95°C. The storage medium then usually consists of a special heating oil or a steam boiler system.

[0013] The heated storage medium flows via pipe (7) to the lower connection of the mechanical 3-way thermostatic mixer (2). The temperature regulator (3), which is integrated directly into the 3-way thermostatic mixer, is set so that a temperature of, for example, 55°C is achieved at the upper outlet (2b). The 3-way thermostatic mixer (2) consists of a mechanical thermostatic valve with a cylindrical capsule filled with thermal wax or thermal oil, which is moved against a preloaded spring. The expansion of the thermal oil can open or close the third connection coming from the right, allowing more or less cooled storage medium to flow through pipe (9) into the 3-way thermostatic mixer.The temperature regulator (3) allows you to manually pretension the spring that presses on the capsule containing thermal oil. The capsule opens or closes depending on the desired temperature. The mixture of the hot storage medium from pipe (7) and the cooled medium from pipe (9) creates the desired mixed temperature of the storage medium in pipe (2b). The desired mixed temperature is usually between 55°C and 60°C.

[0014] The cold domestic water, which flows into the heat exchanger (1) through pipes (12) and (12b), flows through it and is heated in countercurrent by the storage medium, and exits the heat exchanger (1) again via pipe (11). The temperature of the outflowing hot water is continuously measured by the sensor (5), which is located in an immersion sleeve (5b) at the outlet of the heat exchanger (1). The temperature control (5a) uses the speed-controlled charging pump (4) - which is controlled, for example, with a 0 to 10 volt signal - to continuously regulate the flow rate of the storage medium in the pipe (2a) so that the preset hot water temperature (5), for example 50°C, is precisely maintained, regardless of the tap volume flowing through the hot water pipe (11).The flow meter (12a) detects the flow of cold water in the cold water pipe (12) when hot water is drawn from a tap in the building and transmits this information via a digital signal to the temperature control (5a), which immediately starts the charging pump (4).

[0015] The circulation line (13) with the circulation pump (14), the circulation sensor (14a), and the circulation control (14b) is only necessary if a circulation line (13) has been installed in the building. The circulation control (14b) can be installed separately or integrated into the domestic hot water control (5a). However, the circulation control (14b) functions independently of the temperature control (3) or (5a) according to the invention.

[0016] Fig.Figure 2 shows the schematic structure of an alternative embodiment of the system according to the invention, wherein the storage medium is brought from a high temperature to a lower temperature by means of a 3-way heating mixer (2c).

[0017] The hot storage medium in the heat accumulator (6) flows via pipe (7) to the lower connection of the 3-way heating mixer (2c). An electrically driven actuator (3a) is located on the 3-way heating mixer (2c), which can adjust the 3-way heating mixer (2c) and open and close it. A temperature sensor (4a) is located in an immersion sleeve (4c) at the inlet of the heat exchanger (1). This sensor is connected to the temperature control (4b). The temperature control (4b) controls the actuator (3a) so that a temperature of, for example, 55°C is created at the outlet (2b) of the 3-way heating mixer (2c). The 3-way heating mixer (2c) is supplied with hot storage medium via pipe (7), while cooled storage medium can flow in via pipes (8) and (9). The temperature control (4b) is now set so that the hot storage medium from the pipe (7) is mixed with the cooled storage medium from the pipe (8 or 9).9) is mixed in a certain ratio so that the set mixing temperature of, for example, 55°C is achieved at the outlet (2b).

[0018] The cold domestic water, which flows into the heat exchanger (1) through the cold water line (12) and the pipe (12b), flows through it and is heated in countercurrent by the storage medium, and exits the heat exchanger again via the hot water line (11). The temperature of the outflowing hot water is continuously measured by the sensor (5), which is located in an immersion sleeve (5b) at the outlet of the heat exchanger (1). The temperature control (5a) uses the speed-controlled charging pump (4) - which is controlled, for example, with a 0 to 10 volt signal - to continuously regulate the flow rate of the heating medium in the pipe (2a) so that, regardless of the tap volume flowing through the hot water line (11), the preset hot water temperature measured with the sensor (5), for example 50°C, is precisely maintained.

[0019] The circulation line (13) with the circulation pump (14), the circulation sensor (14a), and the circulation control (14b) is only necessary if a circulation line (13) has been installed in the building. The circulation control (14b) can be installed separately or integrated into the temperature control (5a). However, the circulation control (14b) functions completely independently of the inventive domestic hot water control (4b) or (5a). List of reference symbols: 1 heat exchanger 2 3-way thermostatic mixers 2a Flow line to the heat exchanger 2b Supply line to the charging pump 2c 3-way heating mixer 3 Temperature control 3a Actuator for heating mixer 4 Charging pump 4a Temperature sensor 4b Temperature control 4c immersion sleeve 5 temperature sensors 5a Temperature control 5b Immersion sleeve 6 heat storage 7 Flow line 8 Return line 9 Return line 10 Return line 11 Hot water pipe 12 cold water pipe 12a Flow meter 12b Pipeline 13 Circulation line 14 Circulation pump 14a Temperature sensor circulation 14b Circulation control QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 102019107179A1

[0007] DE 202016007060U1

[0007] EP 2226571A1

[0007] EP 2366955A2

[0007] EP 1798486A2

[0007] EP 2369243 B1

[0007] EP 20180711

[0007] EP 0356371A1

[0007]

Claims

[1] The highly efficient fresh water station according to the invention has a heat storage tank (6) filled with hot storage medium, a 3-way thermostatic mixer (2) with an integrated temperature control (3), a heat exchanger (1), a temperature sensor (5) with a connected temperature control (5a), a flow meter (12a), and a charging pump (4), a) wherein the charging pump (4) pumps the hot storage medium out of the heat storage tank (6) through the pipe (7), through the 3-way temperature mixer (2), through the pipes (2b) and (2a), into the heat exchanger (1), through the heat exchanger (1) and back through the pipes (8) and (10) into the heat storage tank (6), b) whereby the 3-way temperature mixer (2) brings the hot storage medium to a lower temperature by adding cooled storage medium via the return line (9), c) the integrated temperature control (3) controls the 3-way temperature mixer in the mixing ratio so that the storage medium can flow into the heat exchanger (1) in the pipe (2b) and (2a) at the constant temperature set on the temperature controller (3), d) the temperature sensor (5) measures the temperature of the domestic water flowing out of the heat exchanger (1) and transmits the measured value to the temperature control (5a), e) the temperature control (5a) controlling the speed of the charging pump (4) so ​​that the service water temperature flowing out of the heat exchanger (1), measured at the temperature sensor (5), is constant, f) the temperature of the storage medium in the heat storage tank (1) may be significantly higher than the target temperature of the domestic water set on the control system (5a), g) whereby the heated domestic water flows via the pipe (11) at a constant temperature to the individual taps in the building and the consumer does not notice any temperature fluctuations. [2] Fresh water station according to claim 1, characterized by that the 3-way thermostatic mixer (2) can also consist of a 3-way heating mixer (2c), a) wherein a temperature sensor (4a) is positioned in the inlet of the heat exchanger (1), b) wherein the temperature sensor (4a), which is installed in an immersion sleeve (4c), transmits the measured value to the temperature control (4b), c) wherein the temperature control (4b) controls the mixing ratio of the 3-way heating mixer (2c) by means of the servomotor (3a) in such a way that a constant temperature is measured at the temperature sensor (4a), d) whereby the temperature of the storage medium in the heat storage tank (1) may be significantly higher than the target temperature of the domestic water set on the control system (5a), [3] Fresh water station according to claim 1, characterized by that the temperature of the storage medium in the heat storage tank (1) may be as high as the manufacturer of the heat storage tank (1) allows and yet the controls (3) and (5a) are able to keep the set domestic hot water temperature, measured at the temperature sensor (5), constant. [4] Fresh water station according to claim 1, characterized by that the heat exchanger (1) consists of a plate heat exchanger. [5] Fresh water station according to claim 1, characterized bythat the heat exchanger (1) consists of a tube bundle heat exchanger. [6] Fresh water station according to claim 1, characterized by that the heat exchanger (1) can be made of any suitable material or of any suitable shape. [7] Fresh water station according to claim 1, characterized by that the temperature sensors (5) and (4a) can optionally also be designed as contact sensors.

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