HEATING APPLIANCE, METHOD FOR OPERATING A HEATING APPLIANCE, COMPUTER PROGRAM PRODUCT, CONTROL AND REGULATION DEVICE

Description

[0001] The invention relates to a heating device, a method for operating a heating device, a computer program product and a control and regulating device.

[0002] Hot water heaters typically have a defined heat output, which is used to heat a volume of cold water (also referred to as the "draw-off rate"). These heaters are often connected to a central cold water supply, which, due to its high pressure, allows for high flow rates. The heat output of the heater and the volume of cold water to be heated must be in a specific ratio to achieve the desired temperature difference (temperature increase) of the cold water. This temperature difference is often between 35 K and 40 K [Kelvin], which would heat cold water at a temperature of 10 °C to a temperature of 55 to 60 °C [degrees Celsius].A high volume flow rate of the cold water to be heated may require a heat output that exceeds that of the heat generator, and as a result, hot water would be provided that is colder than the desired temperature, or vice versa.

[0003] According to current technology, regulating valves can be used to limit the cold water flow rate and thus set a minimum hot water temperature. These regulating valves are installed and permanently set on-site by a qualified technician. Another solution is the use of flow restrictors, which can automatically regulate a fixed flow rate. The disadvantages of these solutions are their static nature, and they can often lead to uncomfortable situations for the user, such as when the hot water is too hot or the flow rate is insufficient. In particular, these solutions cannot meet user-specific needs, such as a higher temperature or a higher flow rate.

[0004] CN 108 626 777A proposes a wall-mounted boiler comprising a main heat exchanger and a plate heat exchanger arranged in a circuit, with a mixing chamber incorporated within the plate heat exchanger to compensate for temperature fluctuations. This arrangement is elaborate and complex.

[0005] US 2020 / 292 179 A1 proposes the arrangement of a bypass line between a cold water inlet and a hot water outlet of a heat exchanger and a controllable bypass valve, by means of which a mixing ratio of hot water to cold water, and thus a temperature of the outgoing hot water, can be set. This solution is also elaborate and complex.

[0006] A similar arrangement, including a bypass line between the cold water inlet and hot water outlet, is described in US 2021 / 102 713 A1. Here, too, a three-way valve allows the flow rate in the bypass line to be adjusted, and the hot water temperature can be set by the mixing ratio between the cold water in the bypass line and the water heated in a heat exchanger. However, providing a bypass line is disadvantageously expensive.

[0007] The GB 258 3223 A proposes a domestic hot water supply system comprising a first and a second heat exchanger. The hot water can flow through both heat exchangers, being preheated first in the second heat exchanger by a heating return flow. This system also includes a bypass line between the cold water inlet and the hot water outlet, in which a valve is installed to regulate the hot water temperature. However, the provision of a bypass line is again a disadvantage and therefore complex.

[0008] Based on this, the object of the invention is to propose a heating device and a method for operating a heating device that at least partially overcome the problems of the prior art described above. In particular, it aims to create a comfortable hot water supply that can provide a constant outlet temperature and a sufficient flow rate. Specifically, the invention should enable quick and easy adjustment of the hot water supply to user-specific needs.

[0009] Furthermore, the invention should not significantly increase the complexity of a heating device compared to the prior art, should require only minor structural changes to a heating device, and should enable easy integration into an existing production process.

[0010] These problems are solved by the features of the independent claims. Further advantageous embodiments of the solution proposed here are specified in the independent claims. It should be noted that the features listed in the dependent claims can be combined with one another in any technologically meaningful way and define further embodiments of the invention. Furthermore, the features specified in the claims are further specified and explained in the description, which also presents further preferred embodiments of the invention.

[0011] This system includes a heating unit comprising a heat exchanger and at least one heat generator designed to transfer heat to a heating circuit. The heating circuit is connected to the heating unit via a flow and return line, with the heat exchanger positioned between the flow and return lines. The heat exchanger is designed to transfer heat from the heating circuit to a (definable) volume of domestic hot water. Furthermore, a controllable stepper motor valve is located in a cold water inlet and / or a hot water outlet of the heat exchanger. This valve is designed to adjust or control the volume of domestic hot water flowing through the heat exchanger. A reduction in the domestic hot water flow rate increases the temperature of the domestic hot water at the hot water outlet, while an increase in the domestic hot water flow rate decreases the temperature of the domestic hot water at the hot water outlet.The heating unit also includes a control loop designed to regulate the temperature measured by the temperature sensor at the hot water outlet as the controlled variable, where the reference variable is a (measured) setpoint temperature and the manipulated variable is the opening width of the controllable stepper motor valve. The control can be implemented, in particular, on a control unit of the heating unit.

[0012] The heating appliance may, in particular, include a heat generator that burns a fuel (such as oil, gas, or hydrogen), releasing heat and transferring it via a heat exchanger to a heat transfer medium (usually heating water) that can circulate in a heating circuit. The heating circuit can be connected to the heating appliance via a flow pipe (into which the heat transfer medium, heated by the heating appliance's heat exchanger, flows) and a return pipe.

[0013] The heating appliance in question is a so-called combination boiler, capable of providing both heating and hot water. Domestic hot water heated by the boiler can be routed directly to a point of use (tap) after heating, for example, due to a lack of space for a (temporary) storage tank. This places high demands on temperature control. For space reasons, such combination boilers are often wall-mounted.

[0014] The service water is primarily drinking or process water that does not come into contact with the heat transfer medium. It is usually drinking water, meaning that all components coming into contact with it must comply with legal food safety regulations. The invention is specifically designed for heating a volume of service water for hot water preparation.

[0015] According to the invention, a heat exchanger is arranged between the flow and return lines of the heating appliance. This heat exchanger can be supplied with a volume flow of heat transfer medium and a volume flow of domestic water, so that a heat flow from the heat transfer medium to the domestic water can be established, and heated domestic water can be provided. The heat exchanger can, in particular, be a plate heat exchanger.

[0016] The heat exchanger can be connected to a (cold) water supply via a cold water inlet, often a water network with adjustable water pressure. A hot water outlet allows the heated flow of usable water to exit the heat exchanger and be made available at a point of use, such as a tap or shower.

[0017] Hot water withdrawal can be detected by the heating unit via a flow measuring device, for example a paddle wheel sensor, and subsequently a valve (three-way valve) is opened, and at least part, but usually the entire, volume flow of heat transfer medium (heated by the heat generator) is supplied to the heat exchanger and thus made available for the production of hot water.

[0018] The heating unit features a stepper motor valve in the cold water inlet or hot water outlet of the heat exchanger. This stepper motor valve is designed to adjust or control the flow rate of domestic hot water through the heat exchanger. Specifically, the opening position of a valve closure element and / or the opening width of a flow-through port in the valve can be adjusted. The stepper motor valve can variably increase, decrease, and / or fix the flow rate of domestic hot water as needed (in several steps). Reducing the flow rate increases the temperature of the domestic hot water at the outlet. Increasing the flow rate decreases the temperature of the domestic hot water at the outlet.

[0019] The stepper motor valve can be controlled, in particular via an electrical signal, and can be electrically connected to a control unit of a heating device.

[0020] According to an advantageous embodiment, the heating device can include a temperature sensor in the hot water outlet of the heat exchanger and a flow sensor for measuring the volume flow of water.

[0021] According to an advantageous embodiment, the heating appliance can include a device for detecting a target temperature and / or a target flow rate. This device can allow a user to make their own (user-specific) adjustments. According to a simpler embodiment, the target temperature and / or target flow rate can be detected by a separate device, for example, located in a bathroom.

[0022] A setpoint temperature represents the desired temperature of the heated domestic hot water, and the setpoint flow rate represents the desired flow rate. For example, the desired flow rate can vary depending on the user's preferences and the shower fittings used. It is understood that the setpoint flow rate and setpoint temperature can only be selected within certain limits, with the maximum heat flow rate supplied by the heat generator representing a significant limit. If the setpoint flow rate and setpoint temperature cannot be achieved simultaneously, it can be determined which parameter should be set as the priority. With a low setpoint temperature combined with a low setpoint flow rate and the associated low required heat flow, it is advantageous to reduce the output of the heat generator (as described below).

[0023] According to a further advantageous embodiment, the device for recording a target temperature and / or a target volume flow rate can be supported by a computer program. The computer program can, in particular, be executed on a mobile device, which can establish a data connection with the heating device.

[0024] Furthermore, the system for recording the desired temperature and / or flow rate can be voice-controlled or controlled by a voice assistant. Particularly in conjunction with a computer program and the use of a microphone in a mobile device or a room-integrated voice assistant, a very high level of convenience can be achieved. For example, this allows a user to set their preferred settings by (loudly) pronouncing a keyword (e.g., "shower") and / or their name (or another profile identifier). If the user deviates from the profile's default settings, they can also specify a desired target temperature and / or flow rate. Similarly, user profiles can be created, user profile defaults changed, and / or profile-independent settings selected, for example, for a guest.

[0025] Furthermore, the system for recording the setpoint temperature and / or setpoint flow rate can advantageously include a database that assigns a user their preferred setpoint temperature and / or setpoint flow rate, possibly for different usage types (bathing, showering, etc.). This would allow for convenient recording via (voice) recognition of a name and, if applicable, a usage type.

[0026] According to an advantageous embodiment, a further control variable can be the output of the heat generator. Heat generators of heating appliances are often operated at their rated output for domestic hot water supply. When a small volume of hot water is drawn at a low temperature, and thus the heat demand for the draw-off is noticeably below the rated output of the heat generator, its output can be reduced. Advantageously, this enables particularly energy-efficient operation of the domestic hot water supply and also reduces water consumption, since temperature adjustment can be made considerably faster. The output (or speed) of a circulation pump arranged in the heating circuit can also be included as a further control variable.

[0027] Following another aspect, a procedure for operating a heating device proposed here is specified, comprising the following steps: a) Determining a target temperature for hot water preparation, b) Controlling the temperature of the hot water outlet to the target temperature determined in step a), where the control variable is the volume flow rate of the domestic water.

[0028] According to an advantageous embodiment, a target volume flow rate can also be recorded in step a).

[0029] A suitable controller for regulating temperature can be, in particular, a proportional (P) controller, which meets at least basic requirements. Improved control can be achieved with a polynomial (PI) controller.

[0030] The control loop of the control system could consist of the stepper motor valve, the heat exchanger and connecting lines.

[0031] According to a further advantageous embodiment, the (current) output of the heat generator can be included as an additional control variable. In particular, the output of the heat generator can be throttled / reduced when there is a low demand for heat.

[0032] According to an advantageous embodiment, in step a) a user or user ID can be recorded, and a target temperature and / or a target flow rate can be assigned to the user based on data stored, for example, in a database. It should be noted that this embodiment does not necessarily require the heating device to include a control loop configured to regulate the detected temperature at the hot water outlet as the controlled variable, where the reference variable is a target temperature and the manipulated variable is the opening position of the controllable stepper motor valve.

[0033] According to an extension, an additional usage type can be recorded, which must also be stored in the database, so that the target temperature and / or target flow rate can be assigned based on the user (identification) and the usage type. Such a design can be particularly convenient in conjunction with a voice assistant for recording the target temperature and / or target flow rate, as the user only needs to speak their name and the usage type aloud to enter or record the target temperature and / or target flow rate.

[0034] According to another preferred embodiment, information about users, water withdrawal (e.g., withdrawal duration and flow rate), and the time (time, day of the week) can be stored and analyzed. Artificial intelligence or machine learning can be used for data analysis. As a result, a prediction of user behavior can be generated, enabling even more convenient and energy-efficient hot water preparation. It should be noted that this embodiment does not necessarily require the heating appliance to include a control loop configured to regulate the measured temperature at the hot water outlet as the control variable, where the reference variable is a setpoint temperature and the manipulated variable is the opening position of the controllable stepper motor valve.

[0035] According to another aspect, a computer program product is proposed, comprising commands that cause a heating device proposed here to perform a procedure described above.

[0036] Another aspect is the proposal for a control unit for a heating appliance, designed to carry out the procedure presented here. This control unit can, for example, include or be equipped with a processor. In this context, the processor can, for instance, execute the procedure stored in the control unit's memory.

[0037] Another aspect is the suggestion of using a stepper motor valve to control the temperature of a hot water system.

[0038] The details, features, and advantageous configurations discussed in connection with the process may also occur in the computer program, control unit, heating device, and / or application presented here, and vice versa. In this respect, full reference is made to the explanations provided therein for a more detailed characterization of the features.

[0039] This document describes a heating appliance, a method for operating it, a computer program, and a control device that at least partially solve the problems described with reference to the state of the art. In particular, the heating appliance, the method, and its application contribute to achieving a user-friendly, user-adjustable, and energy-efficient hot water supply.

[0040] Furthermore, the invention can be implemented particularly easily from a technical perspective, as only very minor structural changes are required.

[0041] The invention and its technical context are explained in more detail below with reference to the accompanying figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the situations described in the figures and combine them with other components and findings from the present description. It should be emphasized that the figures, and especially the depicted dimensions, are only schematic. They show: Fig. 1: a heating device proposed here, and Fig. 2: a control loop of a heating device proposed here.

[0042] Fig. 1The diagram shows an example and schematic of a heating device 1 proposed here, which can be designed as a wall-mounted combination heating device.

[0043] The heating appliance 1 uses a fuel gas (natural gas, hydrogen) as fuel, which can be supplied to the heating appliance 1 via a gas supply 18. In a gas valve 5, fuel gas can be added to a mass flow of combustion air and supplied to a heat generator 4 (also called a burner) located in a combustion chamber 21, where it can combust, releasing heat. A conveying device 3, often designed as a blower, can convey an airflow of combustion air or combustion mixture for this purpose. The combustion products can be discharged into an exhaust system 20, and any condensate produced during combustion can be discharged into a condensate drain 8. The heat generated during combustion in the heat generator 4 can be transferred via a heat exchanger 2 (often also called a primary heat exchanger) to a heat transfer medium circulating in a heating circuit 13 in a circulation direction 22.

[0044] The heating circuit 13 can include a supply line 14, through which heated heat transfer medium is supplied to consumers in a circulation direction 22, and a return line 15, through which cooled heat transfer medium can flow back into the heat exchanger 2. A flow sensor 7 in the heating circuit can measure the flow rate of heat transfer medium (often heating water) in the heating circuit 13, which is pumped by a circulation pump 9.

[0045] A heat exchanger 19, connecting the flow 14 and return 15 of the heating circuit 13, is designed to heat a volume of domestic hot water. The volume of water to be heated can be supplied to the heating unit 1 via a cold water inlet 17 and, after heating in the heat exchanger 19, supplied to a draw-off point (tap) via a hot water outlet 16. A hot water flow sensor 10, often designed as a paddle wheel sensor, can detect the volume of domestic hot water to be heated. A three-way valve 11 can direct the volume of heat transfer medium in the heating circuit 13 through the heat exchanger 19 or supply it to consumers, such as radiators or underfloor heating systems, via the flow 14 and return 15. Additionally, a stepper motor valve 12 can be arranged in the cold water inlet 17 to control the volume of water flowing in the cold water inlet 17. A temperature sensor can be arranged in hot water outlet 16 (hot water outlet 23).A pressure expansion vessel 6 can compensate for volume changes of the water in the heat exchanger 19 caused by temperature fluctuations.

[0046] A control unit 24 can be electrically connected to the conveying device 3, the three-way valve 11, the heating circuit flow sensor 7, the hot water flow sensor 10, the stepper motor valve 12, and the circulation pump 9, and can be configured to regulate and control the combustion process in the heat generator 4. Furthermore, the control unit 24 can be electrically connected to a data acquisition device 30, which enables the detection of the target temperature and / or target flow rate of the hot water by user input. The data acquisition device 30 can be a mobile device that can be connected to the control unit 24 via a wireless connection (e.g., a Bluetooth connection).

[0047] A hot water draw-off process can proceed as follows. By opening a tap, a flow of water from the cold water inlet passes through the heat exchanger 19 to the hot water outlet 16, which can be detected by the hot water flow sensor 10. After the hot water flow sensor 10 detects the draw-off, the control unit 24 can move the three-way valve 11 to a position in which the heating circuit 13 can be routed through the heat exchanger 19 to heat the flow of water from the cold water inlet 17.

[0048] A heating device 1 proposed here can now regulate the volume flow of water to be heated through the heat exchanger 19 by means of the stepper motor valve 12, so that the temperature detected at the hot water outlet temperature sensor 23 can be kept as constant as possible at a set temperature.

[0049] An example and schematic diagram can be used to illustrate this. Fig. 2The control loop shown in section 25 can be used. In a calculation of the maximum volume flow rate 26, the maximum possible volume flow rate of process water can be determined. V̇ max (with a specific heat capacity cp,water ), which is proportional to a mass flow rate of hot water m max The temperature at which the cold water temperature TKW can be heated to the target temperature Ttarget using the maximum output of the heat generator 4P max can be calculated. For example, the following formula can be used: V ˙ max ≅ m ˙ max = P ˙ max c p , Wasser ∗ T Soll − T KW

[0050] This calculation can be performed continuously, and the result can be fed to a feedforward control unit 27 as a reference input w(t). A controller 28 can receive a difference e(t) between the calculated volume flow w(t) and a measured volume flow y(t) as a reference input. The feedforward control unit 27 serves to accelerate the adjustment of the cold water volume flow when the setpoint temperature changes, for example, by an increase of 3 K [Kelvin], which, with the device operating at full capacity P max, results in a reduction of the maximum possible volume flow w(t). The controller transmits a calculated step value u(t) to the stepper motor valve 12, which is part of a control loop 29.

[0051] The control loop 29 can essentially comprise the stepper motor valve 12, the necessary pipework 31 and the heat exchanger 19 and can be influenced by environmental factors d(t), for example pressure and temperature fluctuations in the system.

[0052] The in Fig. 2The control loop 25 shown can be used particularly in the steady-state operation of the hot water supply of the heating appliance 1, where calculating and controlling a difference e(t) is useful. During the start-up phase of hot water supply, calculating the difference e(t) is not practical, as the system first needs to heat up and the goal is to reach the target temperature as quickly as possible. For this purpose, a control system can be chosen in which the calculated volume flow w(t) is transmitted to a control unit, which derives a step value u(t) for the stepper motor valve 12 and transmits this signal u(t) to a control loop, which essentially corresponds to the control loop 29. Reference symbol list

[0053] 1 Heating unit 2 Heat exchanger 3 Conveyor 4 Heat generator 5 Gas valve 6 Expansion vessel 7 Heating circuit flow sensor 8 Condensate drain 9 Circulating pump 10 Hot water flow sensor 11 Three-way valve 12 Stepper motor valve 13 Heating circuit 14 Flow 15 Return 16 Hot water outlet 17 Cold water inlet 18 Gas supply 19 Heat exchanger 20 Exhaust system 21 Combustion chamber 22 Circulation direction 23 Hot water outlet temperature sensor 24 Control unit 25 Control loop 26 Maximum flow rate calculation 27 Pilot control 28 Controller 29 Control loop 30 Detection device 31 Pipe routing

Claims

1. Heating device (1) comprising a heat exchanger (19) and at least one heat generator (4) which is designed to transfer heat to a heating circuit (13), wherein the heating circuit (13) can be connected to the heating device (1) via a flow pipe (14) and a return pipe (15) and the heat exchanger (19) is arranged between the flow pipe (14) and the return pipe (15), and is designed to transfer heat from the heating circuit (13) to a volume flow of domestic water, wherein a controllable stepper motor valve (12) is arranged in a cold water inlet (17) and / or a hot water outlet (16) of the heat exchanger (19) and is designed to adjust or control the volume flow of domestic water flowing through the heat exchanger (19), wherein xml-ph-0000@deepl.internal volume flow of service water flowing through the heat exchanger (19), wherein a reduction in the volume flow of service water causes an increase in the temperature of the service water in the hot water outlet (16) and an increase in the volume flow of service water causes a reduction in the temperature of the service water in the hot water outlet (16), wherein the heating device (1) comprises a control circuit (25) which is designed to control the detected temperature in the hot water outlet (16) as a control variable, wherein the reference variable is a setpoint temperature and the manipulated variable is an opening position of the controllable stepper motor valve (12).

2. . Heating device (1) according to claim 1, wherein the heating device (1) comprises a temperature sensor (23) for detecting a temperature in the hot water outlet (16) of the heat exchanger (19) and a hot water volume flow sensor (10) for detecting the volume flow of domestic water.

3. . Heating device (1) according to one of the preceding claims, wherein the heating device (1) comprises a device for detecting (30) a setpoint temperature.

4. . Heating device (1) according to claim 3, wherein the device for detecting (30) a setpoint temperature is supported by a computer programme and comprises contactless recognition and / or voice control.

5. . Heating device (1) according to one of the preceding claims, wherein a further control variable is a power output of the heat generator (4) and / or a power output of a circulation pump (9).

6. . Method for operating a heating device (1) according to one of the preceding claims, comprising at least the following steps: a) Detecting a setpoint temperature for hot water preparation, b) regulating the temperature of the hot water outlet (16) to the setpoint temperature detected in step a), wherein the control variable for the control is the volume flow of the domestic water to be heated, wherein a reduction in the volume flow of domestic water causes an increase in the temperature of the domestic water in the hot water outlet and an increase in the volume flow of domestic water causes a reduction in the temperature of the domestic water in the hot water outlet.

7. . Method according to claim 6, wherein in step b) the output of the heat generator (1) and / or a circulation pump (9) is included as a further control variable.

8. . Method according to one of claims 6 or 7, wherein in step a) a target volume flow is recorded in addition to the target temperature.

9. . Method according to one of claims 6 to 8, wherein in step a) a user is detected to whom a setpoint temperature and / or a setpoint volume flow is assigned.

10. . Method according to claim 9, wherein the hot water consumption of at least one user is analysed and included in the execution of step a).

11. . Computer program product comprising instructions that cause the heating device (1) according to one of claims 1 to 5 to execute a method according to one of claims 6 to 10.

12. . Control and regulation device (24) for a heating device (1), designed to carry out a method according to one of claims 6 to 10.

13. . Heating device (1) according to one of claims 1 to 5, comprising a control and regulation device (24) according to claim 12.