EP3835667B1 - Method for controlling a heating system and control device for same - Google Patents

Description

The invention relates to a method for controlling a heating system, preferably with a condensing boiler as the heat generator, with at least one heating circuit for heating the building and with hot water preparation for heating service water to a hot water target temperature. The heated service water can, for example, be stored in a hot water storage tank. A heat generator flow temperature is selected to be greater than or equal to the heating circuit target temperature, and a mixer is provided for setting a heating circuit target temperature, i.e. for setting the actual heating circuit temperature in accordance with the heating circuit target temperature. The invention also relates to a control device set up to carry out the method described below or parts thereof.

When it comes to controlling the heating system, a situation in which the heat source flow temperature is selected to be as low as possible is preferred in terms of energy. This is done by controlling the heating system. For this purpose, the heat source flow temperature in heating mode is selected so that it exceeds the heating circuit target temperature just far enough for a heat transfer medium circulating in the heating circuit to be heated to the heating circuit target temperature. The same applies to all heating circuits if there is more than one heating circuit. The heat generator typically reheats when a heating controller determines that the actual temperature of the heating circuit falls below the target temperature of the heating circuit by an adjustable amount and the actual temperature of the heating circuit should be increased, but the heat generator flow temperature is too low to generate the actual temperature of the heating circuit .

In a control system that is particularly optimal for condensing boilers, the heat generator flow temperature can be selected in such a way that the condensing boiler heats evenly over the long term and provides just such a heat output that the actual heating circuit temperature can be maintained in all heating circuits. If the heat generator flow temperature exceeds the heating circuit setpoint temperature by more than a parameterizable value, the heat generator switches off until it has to be reheated as described above in order to maintain the heating circuit setpoint temperature.

The mixer mixes the heat transfer medium from the heat generator (with the heat generator flow temperature) if necessary with the heat transfer medium from the heating return (which has a lower temperature) in order to set the heating circuit setpoint temperature as the actual heating circuit temperature. This is usually done by a controller that monitors the deviation of the actual heating circuit temperature from the heating circuit target temperature and uses a variable to act on the mixer in the heating circuit in such a way that the actual heating circuit temperature corresponds to the target heating circuit temperature.

This is a preferred heating control with which the invention can be used. However, it is not necessarily limited to such a control or regulation concept.

In heating systems for building heating and hot water preparation with a heat generator, it is provided that the heat generator heats a heat transfer medium to a heat transfer medium flow temperature and delivers it to the building heating and hot water preparation via a flow. The heat transfer medium from the building heating (i.e. from the heating circuits) and from the hot water preparation flows via a return flow back to the heat generator, which heats up the heat transfer medium again, after the heat energy has been released in the systems (building heating, hot water supply).

The efficiency of a condensing boiler preferred according to the invention is essentially determined by the heat generator return flow temperature of the heat transfer medium that is fed to the heat generator for heating. The return is made up of the building heating return (all heating circuits) and the hot water generation return (of the hot water storage tank loading circuit).

In order to achieve a high heating efficiency of the condensing boiler, the return temperature of the heat transfer medium returned to the heat generator should be as low as possible, preferably in the range between 20°C and 40°C and in any case not exceed the condensing limit temperature of about 57°C. Above this temperature, the efficiency gain of the condensing technology is only small. It is therefore advantageous to select the heating circuit flow temperature (heating circuit setpoint temperature) in such a way that the thermal output released in the heating circuit cools the heat transfer medium down to near room temperature. The condensing boiler then generates just the heat output required in heating mode and runs continuously with a high degree of efficiency.

The return temperature from the hot water preparation depends on the flow temperature and the flow rate in the charging circuit as well as the charging status and the design of any hot water storage tank. The return temperature from the hot water preparation is typically well above the return temperature of the heating circuit. The efficiency of the condensing boiler is therefore significantly lower during hot water preparation than in heating mode.

However, a condensing boiler in the sense of this text is understood not only as a condensing boiler in the sense described above, the efficiency of which depends significantly on the return temperature of the heat carrier heated in the heat generator. Under a condensing boiler within the meaning of this text is generally understood to mean a heat generator that can be operated more efficiently in the heating mode of a building than in the hot water preparation, which often requires higher heat generator temperatures than the heating mode. Condensing boilers within the meaning of this text can be heat generators that generate heat locally by converting final energy (e.g. oil, gas, pellets) in a boiler, combined heat and power plant, heat pump or similar, or obtain heat from a district or local heating network.

Heating systems with heating mode and hot water preparation are often operated with a hot water priority circuit. Such a hot water priority circuit is supported by every common heating regulation or heating control. Here, the heat supply to the heating circuit is stopped while the service water is being heated during hot water preparation. The temperature of the heat generator (boiler temperature or heat generator flow temperature) is increased and the drinking or process water in the hot water storage tank is heated. When the process water temperature in the hot water storage tank has reached the hot water target temperature, an after-running phase of usually a few minutes is activated, in which the heat generator can transfer most of its residual heat to the hot water storage tank when it is switched off. The charging branch for hot water preparation is then switched off and the heating circuit switched on again for heating operation.

In this solution, which is frequently used in the prior art, the heat generation for hot water preparation and the heat generation for the heating operation (working circuit supply) are completely separated. In the manner already described, the thermal energy for supplying the heating circuit is generated at a comparatively low heat generator flow temperature. The residual heat remaining in the heat generator after hot water preparation, which comes from less efficient operation of the heat generator, still flows into the heating circuit before it returns to the energy-efficient one Way at the lower temperature level (with suitable return temperatures for condensing technology) can be operated. This means that part of the space heating energy is also generated in a less energy-efficient manner. This proportion is kept as low as possible by the hot water priority circuit.

A disadvantage of the hot water priority circuit is that the building heating or its heating circuit or heating circuits is not supplied with heat during the hot water preparation period. Depending on the size of the hot water storage tank and/or the hot water requirement in the building, this period of non-supply of the building heating with heat can be 20 to over 40 minutes. With some heating controllers, the heating pump is switched off during hot water preparation, which can be perceived by the occupants of the building as a failure of the heating system, especially if a cooled radiator is to be put into operation during this time. Other heating controllers close the mixer in the heating circuit, but allow a heating circuit pump to continue running. The heating circuit is then operated without heat supply. This also leads to severe cooling, but due to the perceptible flow of the heat transfer medium in the radiator, it is not directly perceived as a failure of the heating system.

This disadvantage of room heating comfort can be remedied by deactivating the hot water priority circuit. The heating circuit is operated continuously, even during hot water preparation. However, this mode of operation has the disadvantage that the entire space heating energy, with which the heating circuit is supplied during hot water preparation, is generated at a less energy-efficient operating point of the heat generator.

In any case, it is disadvantageous that the heat generator is not operated in an energy-efficient manner during hot water preparation and during the transition from hot water preparation to heating operation.

The DE 44 38 881 A1 discloses a heating system with a condensing boiler, heating circuits, a service water boiler and a service water circuit and a control device for this, which sets priority operation of the service water circuit or parallel operation of heating and service water circuits depending on the outside, room, boiler water and/or service water temperature. The U.S. 2018/120824 A1 relates to a similar heating system with a control unit that prompts a consumer to end hot water consumption if the heating mode has to be switched back on first. In the DE 43 13 277 C1 , DE 197 01 823 A1 , EP 0 608 500 A1 and EP 3 492 828 A1 similar heating systems and methods for their operation for heating and/or hot water supply are described.

In the essay " More profit from the heat pump", IKZ message, issue 20/2004, page 40ff . an optimization of service water operation and heating operation with a mixing distributor is described, in which a special multi-way mixer is used. This special hydraulic circuit also enables parallel operation of heating and service water heating. In a system with a hot water tank and a heating circuit, the multi-way mixer intercepts the still high-temperature return behind the hot water tank and first directs it into the heating circuit of the building heating system (i.e. the flow of the heating circuit) before it is routed into the return of the heat generator. Although this is effective, it requires the use of a special multi-way mixer, which must also be controlled accordingly as part of the heating control system. Retrofitting existing heating systems is expensive because structural measures are always required.

Against this background, the object of the invention is to increase the energy efficiency of a heating system with in particular a condensing boiler as a heat generator, building heating and hot water preparation in a simple manner.

This object is achieved according to the invention with the features of claims 1 and 6. For this purpose, a method of the type mentioned at the outset provides in particular that during hot water preparation, in particular at the start of hot water preparation, a regular heating circuit target temperature in heating mode (also referred to as the target flow temperature of the heating circuit) is reduced by a configurable value and increased again after hot water preparation the regular heating circuit setpoint temperature of heating operation is reset. In other words, the regular heating circuit setpoint temperature (after reducing the heating circuit setpoint temperature during hot water preparation) is set again after hot water preparation. The regular heating circuit setpoint temperature can, for example, be taken from a heating curve or from another control and/or regulation system.

This ensures that the mixer in the heating circuit, which is provided for setting the actual heating circuit temperature according to the heating circuit setpoint temperature, closes when the heating circuit setpoint temperature decreases or throttles the flow of the warm heat transfer medium through the heating circuit.

During hot water preparation, little or no heat energy is released from the heat generator into the heating circuit. The energy generated by the heat generator is therefore essentially available for hot water preparation, with the heating circuit still being supplied with heat at least in setback mode if the hot water preparation takes longer, in order to prevent the heating circuit and also the building from cooling down completely. The heating circuit target temperature should be lowered immediately with hot water preparation, at the latest as soon as the start of hot water preparation is detected. Because according to the solution proposed according to the invention, the heating circuit is not separated from a heat supply for the entire duration of hot water preparation, as would be the case with a priority circuit, the inventive method is also referred to as "soft priority circuit". Radiator heaters are particularly preferably provided in the heating circuit, in which case the method is particularly effective and offers the user a significant increase in comfort while at the same time optimizing the efficiency of the heat generation.

In a preferred embodiment of the proposed method, the heating circuit setpoint temperature can be reduced before the heat generator flow temperature is increased during hot water preparation. The heating circuit setpoint temperature can preferably be reduced immediately before the heat generator flow temperature is increased. In this context, “directly” means that after the heating circuit target temperature has been reduced, the controller only waits for a period of time during which it closes the mixer fully or partially. After this positioning time, the heat generator flow temperature can be increased immediately. This is typically done as part of the hot water preparation, in which the hot water should be generated as quickly as possible and therefore the heat generator flow temperature is selected as high as possible; Heat source flow temperatures between 70°C and 90°C are often reached, e.g. around 80°C.

After the positioning time, the mixer is usually closed first, since the actual heating circuit temperature is significantly higher than the (now reduced) heating circuit target temperature and there is therefore no heat requirement in the heating circuit. If the mixer is closed before the heat source flow temperature is increased, an additional surge of heat into the heating circuit is avoided. The heating circuit first cools down by the specified value before heat energy is supplied again (by opening the mixer to a suitable extent). According to one embodiment of the invention, the heating circuit setpoint temperature can be reduced as a "night setback control command" and thus analogous to a night setback, with which the heating circuit setpoint temperature is lowered during the usual sleeping times of the occupants or non-use times in office buildings. Instead of a normal night reduction, a temperature value for reducing the heating circuit setpoint temperature can also be specified as a parameter within the scope of the method proposed according to the invention, e.g. in the order of around -10 K to -15 K or a relative reduction in the heating circuit overtemperature from to about 25% the current heating circuit excess temperature. The excess temperature is the difference between the heating circuit flow temperature and the average building temperature.

In addition, according to the invention, it can optionally be provided that the duration of the reduction in the heating circuit setpoint temperature during hot water preparation is limited and the regular heating circuit setpoint temperature is set again at the latest after the duration has expired, even if the hot water preparation is not yet complete. This maximum duration can preferably be configured, ie it can be specified by the user. If this possibly parameterizable maximum duration, for example in the order of 45 minutes to 1 hour, is exceeded, the heating circuit target temperature (target flow temperature) is increased again to its regular value, which corresponds in particular to the heating curve, by this variant of the proposed method according to the invention. This prevents the building from being undersupplied or cooling down beyond the usual duration of hot water preparation if the hot water preparation should take an unusually long time.

In a further embodiment, the duration of the reduction in the heating circuit setpoint temperature can be learned or determined from the usual duration of hot water preparation in the building by recording the duration of hot water preparation over a certain period of time, i.e. several cycles of hot water preparation, and determining an average duration , whereby the duration of the reduction of the heating circuit setpoint temperature is selected as a multiple of the determined average duration (of hot water preparation). The multiple can be determined by a factor that is an integer or rational number greater than 1, i.e., for example, 1.5 times the determined average duration.

Since the hot water preparation is often specified by the control of the heating system, the controller is the start and end time of the hot water preparation known, so that the duration of hot water preparation can be determined by a simple time difference. The average duration in several hot water preparation cycles is particularly preferably determined over a specific period of time, which is preferably at least one day or several days up to one week. Determining the average duration in a week captures the typical habits of hot water consumption by users in different situations. This forms a statistically meaningful basis for determining the average duration of hot water preparation. This can be determined automatically by the system or the controller. For example, 1.5 times to 2 times the average duration can be selected as a multiple of the average duration in order to limit the duration of the reduction in the heating circuit setpoint temperature. In addition, an absolute maximum duration, for example 1 hour, can also be specified. This also prevents the building from cooling down too much during the cold season.

Since the gain in efficiency in heating operation compared to hot water preparation with classic condensing boilers is only achieved if the temperature of the heat carrier returned to the heat generator in the return does not exceed the condensing value limit temperature already explained, it can be provided in a sensible optional embodiment of the proposed method that the The heating circuit return temperature is measured and the reduction in the heating circuit set temperature is returned (ie ended or reduced) if the heating circuit return temperature is above the condensing limit temperature. With typical condensing boilers, the increase in efficiency depends on the return temperature of the heat transfer medium in the heating circuit. If this temperature is above a calorific value limit temperature, which can be around 57° C., for example, the efficiency gain of the proposed method is only slight. The reduction in the heating circuit setpoint temperature proposed according to the invention can then be returned or reduced down to the value 0, at which the heating circuit setpoint temperature corresponds to the regular heating circuit setpoint temperature, as it is specified for example by a heating characteristic. In this case, the heat would not be generated more efficiently in heating mode than in hot water preparation.

According to a further aspect of the invention, this also includes a control unit for controlling a heating system, preferably with a condensing boiler as the heat generator, with at least one heating circuit for heating the building and with hot water preparation for heating service water to a hot water target temperature, with the service water being stored in a hot water tank, for example of hot water preparation can be saved. The proposed control device has interfaces for controlling the heat generator, the at least one heating circuit and the hot water preparation, as well as a computing device that is set up to carry out the method described above or parts thereof. The computing device can be located both in the control unit on site (local) and, for example, in an IT cloud or a data center (remote). If the computing device is in the IT cloud or in a data center (e.g. in a central IT system), parameters for controlling the heat generator can be downloaded to the control unit, for example via a mobile data transmission interface.

The control unit can be integrated into the control unit that is usually present in the heating system and can have internal interfaces for controlling the heat generator, the at least one heating circuit and the hot water preparation. According to the invention, the control unit can also be provided as a device separate from the heating system and can be connected to the control unit of the heating system via a control interface, for example a suitable bus or other interface via which the aforementioned interfaces can be implemented.

In a simple embodiment, the control unit can carry out a flow temperature simulation and thus indirectly bring the existing control unit of the heating system to adjust the flow temperature.

Preferably, temperature sensors for detecting the heat generator flow temperature, the heat generator return temperature, the heating circuit flow temperature, the heating circuit return temperature and/or the actual hot water temperature can be connected or can be connected to the interfaces of the control unit. This enables the control device to carry out the method proposed according to the invention in a simple and precise manner.

A further refinement of the invention can take place in that the control device controls a mixer of the heating system directly. The control signal from the original heating controller can be recorded by the control unit, interpreted and forwarded to the mixer either unchanged or manipulated. An optimized control of the mixer can be based on measured temperature values or can be achieved with knowledge of the mixer runtime and mixer position.

Further advantages, features and application possibilities of the invention also result from the following description of exemplary embodiments and the drawing.

• Fig. 1 schematisch ein erfindungsgemäßes Steuergerät gemäß einer Ausführungsform der Erfindung, das an eine Heizungsanlage angeschlossen ist;
• Fig. 2 ein schematisches Ablaufdiagramm eines erfindungsgemäßen Verfahrens gemäß einer Ausführungsform der Erfindung;
• Fig. 3 schematisch den zeitlichen Temperarturverlauf der WärmeerzeugerVorlauftemperatur ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$
  
  , der Warmwasserbereitungs-Rücklauftemperatur ${\vartheta }_{\mathit{WW}}^{\mathit{RL}}$
  
  , der Heizkreis-Vorlauftemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$
  
  , der Heizkreis-Rücklauftemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{RL}}$
  
  und der Heizkreis-Solltemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{soll}}$
  
  bei und nach der Warmwasserbereitung ohne Anwendung des erfindungsgemäßen Verfahrens (Stand der Technik);
• Fig. 4 schematisch den zeitlichen Heizleistungsverlauf für die Warmwasserbereitung und den Heizbetrieb bei und nach der Warmwasserbereitung ohne Anwendung des erfindungsgemäßen Verfahrens (Stand der Technik);
• Fig. 5 schematisch den zeitlichen Temperarturverlauf der Wärmeerzeuger-Vorlauftemperatur ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$
  
  , der Warmwasserbereitungs-Rücklauftemperatur ${\vartheta }_{\mathit{WW}}^{\mathit{RL}}$
  
  , der Heizkreis-Vorlauftemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$
  
  , der Heizkreis-Rücklauftemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{RL}}$
  
  und der Heizkreis-Solltemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{soll}}$
  
  bei und nach der Warmwasserbereitung bei Anwendung des erfindungsgemäßen Verfahrens gemäß einer Ausführungsform;
• Fig. 6 schematisch den zeitlichen Heizleistungsverlauf für die Warmwasserbereitung und den Heizbetrieb bei und nach der Warmwasserbereitung bei Anwendung des erfindungsgemäßen Verfahrens gemäß einer Ausführungsform;

Show it:

• 1 schematically an inventive control unit according to an embodiment of the invention, which is connected to a heating system;
• 2 a schematic flow chart of a method according to the invention according to an embodiment of the invention;
• 3 schematic of the temperature curve of the heat generator flow temperature over time ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$
  
  , the water heating return temperature ${\vartheta }_{\mathit{ww}}^{\mathit{RL}}$
  
  , the heating circuit flow temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$
  
  , the heating circuit return temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{RL}}$
  
  and the heating circuit target temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{should}}$
  
  during and after hot water preparation without using the method according to the invention (prior art);
• 4 schematically shows the heating performance over time for hot water preparation and heating during and after hot water preparation without using the method according to the invention (prior art);
• figure 5 schematic of the temperature curve of the heat generator flow temperature over time ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$
  
  , the water heating return temperature ${\vartheta }_{\mathit{ww}}^{\mathit{RL}}$
  
  , the heating circuit flow temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$
  
  , the heating circuit return temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{RL}}$
  
  and the heating circuit target temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{should}}$
  
  during and after water heating when using the method according to the invention according to one embodiment;
• 6 schematically shows the heating output curve over time for hot water preparation and heating operation during and after hot water preparation when using the method according to one embodiment;

In figure 1 an inventive control unit 1 is shown according to an embodiment of the invention. The control device 1 is connected via interfaces 2, 3, 4, 5 to components of a heating system 100 of a building. In the control unit 1 there is also a computing device (not shown) which is set up to carry out the method proposed according to the invention for controlling the heating system 100 . Alternatively, the computing device can be arranged in an IT cloud or in a computing center, in which case there is a communication unit (not shown) in control unit 1 instead of the computing device.

direkt beeinflussen. Über die Schnittstellen 2, 3, 4, 5 werden Steuersignale ausgegeben. Dies ist in der Figur 1 als gestrichelte Linie dargestellt.The heating system 100 has a heat generator 101, preferably designed as a condensing boiler, a heating circuit 111 for heating the building and a water heater 121 for heating service water to a desired hot water temperature. The service water can be tapped by the users of the building. Typically, the water heater 121 also includes an in figure 1 water reservoir, not shown, in which the heated domestic water is stored. Interface 2 connects control unit 1 to heat generator 101. Interface 3 connects control unit 1 to hot water preparation 121. Interface 4 connects control unit 1 to heating circuit 111. Optional interface 5 connects control unit 1 to mixer 112 of heating circuit 111 Via the interface 5, the control device 1 can set the mixer 112 via the activation of the electrically operated mixer motor or servomotor and thus the heating circuit flow temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$

affect directly. Control signals are output via interfaces 2, 3, 4, 5. This is in the figure 1 shown as a dashed line.

aus. Die Temperaturen sind in Figur 1 an den jeweiligen Positionen, an denen sie durch einen Temperatursensor messbar sind, durch einen Punkt mit Bezeichnung dargestellt. Diese Punkte können auch Temperatursensoren repräsentieren, die bspw. über die Schnittstellen 2, 3, 4 (und eine nicht dargestellte Signalübertragung) durch die Steuerung 1 abfragebar sind.The heating circuit 111 is connected to the heat generator flow 102 via a mixer 112 . The heat generator 101 outputs the heated heat transfer medium at a heat transfer medium flow temperature via the heat generator flow 102 ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$

out of. The temperatures are in figure 1 represented by a labeled dot at the respective positions where they are measurable by a temperature sensor. These points can also represent temperature sensors, which can be queried by the controller 1, for example, via the interfaces 2, 3, 4 (and a signal transmission that is not shown).

wird einem ersten Eingang des Mischers 112 zugeführt. Ein zweiter Eingang des Mischers 112 ist mit dem Heizkreis-Rücklauf 114 verbunden, um den Wärmeträger aus dem Wärmeerzeuger-Vorlauf 102 durch Beimischen des (abgekühlten) Wärmeträgers aus dem Heizkreis-Rücklauf 114 abzukühlen und in dem Heizkreis-Vorlauf 113 eine der Heizkreis-Solltemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{soll}}$

entsprechende Heizkreis-Vorlauftemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$

einzustellen. In Figur 1 ist die Heizkreis-Solltemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{soll}}$

nicht eingezeichnet.The heated heat transfer medium with the heat transfer medium flow temperature ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$

is fed to a first input of the mixer 112 . A second input of the mixer 112 is connected to the heating circuit return 114 in order to cool the heat transfer medium from the heat generator flow 102 by adding the (cooled down) heat transfer medium from the heating circuit return 114 and in the heating circuit flow 113 one of the heating circuit set temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{should}}$

corresponding heating circuit flow temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$

set. In figure 1 is the heating circuit target temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{should}}$

not marked.

gespeicherte Wärmeenergie über Wärmetauscher, vorzugsweise Radiator-Wärmetauscher (klassische Heizkörper), teilweise abgegeben. Dabei kühlt sich der Wärmeträger auf die Rücklauftemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{RL}}$

ab. Über den Wärmeerzeuger-Rücklauf 103 wird der Wärmeträger zu dem Wärmeerzeuger 101 zur erneuten Erwärmung rückgeführt.In the heating circuit 111 is in the heat transfer medium with the flow temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$

Stored thermal energy is partially released via heat exchangers, preferably radiator heat exchangers (classic radiators). The heat transfer medium cools down to the return temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{RL}}$

away. The heat transfer medium is fed back to the heat generator 101 for reheating via the heat generator return 103 .

der Warmwasseraufbereitung 121 zugeführt, in der der Wärmeträger die Wärmeenergie über einen Wärmetauscher an das Brauchwasser überträgt, das üblicherweise in einem nicht dargestellten isolierten Wärmespeicher gespeichert wird und zum Zapfen durch den Benutzer zur Verfügung steht. Nach der Abgabe der Wärmeenergie durch den Wärmeträger an das Brauchwasser wird der Wärmeträger über den Warmwasserbereitungs-Rücklauf 122 in den Rücklauf 103 des Wärmeerzeuger 101 rückgeführt. Im Vorlauf ist die Warmwasserbereitung 121 unmittelbar an den Wärmeerzeuger-Vorlauf 102 angeschlossen.To heat service water, the heat transfer medium is used at the heat transfer medium flow temperature ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$

supplied to the hot water treatment 121, in which the heat carrier transfers the thermal energy via a heat exchanger to the hot water, which is usually stored in an insulated heat accumulator, not shown, and is available for tapping by the user. After the thermal energy has been released by the heat transfer medium to the process water, the heat transfer medium is fed back into the return 103 of the heat generator 101 via the hot water preparation return 122 . In the flow, the hot water preparation 121 is connected directly to the heat generator flow 102 .

In a large number of heating systems 100 with one or more heating circuits 111 and hot water preparation 121, hot water preparation 121 is carried out in a so-called priority mode, in which mixer 112 of heating circuit 111 is closed, so that no heat is supplied to heating circuit 111 during hot water preparation 121.

In some cases it is also known to carry out the hot water preparation 121 and the heating operation in parallel in the heating circuit(s) 111 of the building heating system.

At this point it should be noted that in figure 1 for the sake of clarity, only one heating circuit 111 is shown. However, more than one heating circuit 111 can also be provided in buildings; the plurality of heating circuits 111 are then connected to the heat generator flow 102 in a comparable manner, preferably via their own mixer 112 .

und die Heizkreis-Vorlauftemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$

fallen im Gleichklang von einem Temperaturwert ϑ - in dem Beispiel - größer 50 °C auf einen Temperaturwert von etwa - in dem Beispiel - 45 °C ab, der in der Nähe der Heizkreis-Rücklauftemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{RL}}$

liegt. Die Heizkreis-Solltemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$

liegt - in dem Beispiel - bei 50 °C. Zum Zeitpunkt t1 wird parallel zum Heizbetrieb auch die Warmwasserbereitung aktiviert. Dazu wird die Wärmeerzeuger-Vorlauftemperatur ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$

bis - in dem Beispiel - auf etwa 85 °C erhöht und der Wärmeträger der Warmwasserbereitung 121 zugeleitet. Dort überträgt er seine Wärmeenergie teilweise auf das Brauchwasser und verlässt die Warmwasserbereitung 121 mit der Wärmewasserbereitung-Rücklauftemperatur ${\vartheta }_{\mathit{WW}}^{\mathit{RL}}$

, die nur geringfügig niedriger ist als die Wärmeerzeuger-Vorlauftemperatur ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$

und signifikant größer ist als die Heizkreis-Rücklauftemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{RL}}$

.The temperature profile in parallel operation of hot water preparation 121 and heating operation in the heating circuit 111 is in figure 3 shown. At the beginning of the time axis t, the heating system 100 is still in pure heating mode (left side of the time axis before time t1). The heat generator flow temperature ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$

and the heating circuit flow temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$

fall in unison from a temperature value ϑ - in the example - greater than 50 °C to a temperature value of about - in the example - 45 °C, which is close to the heating circuit return temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{RL}}$

lies. The heating circuit target temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$

is - in the example - at 50 °C. At time t1, hot water preparation is also activated parallel to heating operation. The heat generator flow temperature is used for this ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$

to - in the example - increased to about 85 ° C and fed to the heat transfer medium of hot water preparation 121. There it partially transfers its thermal energy to the process water and leaves the hot water preparation 121 with the heating water return temperature ${\vartheta }_{\mathit{ww}}^{\mathit{RL}}$

, which is only slightly lower than the heat generator flow temperature ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$

and is significantly higher than the heating circuit return temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{RL}}$

.

The temperatures mentioned correspond to possible temperature values that can occur in typical systems. The invention is not intended to be limited to these temperature values, which those skilled in the art will adjust as needed.

über das Heizkreis-Solltemperatur-Niveau an. Es dauert eine gewisse Zeit, bis der Mischer 112 in der Lage ist, die Heizkreis-Vorlauftemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$

an die Solltemperatur anzupassen. Es kommt also zu einem Wärmeschub 115 im Heizkreis 111, der durch einen Anstieg der Heizkreis-Vorlauftemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$

gekennzeichnet ist.Due to the - based on the heating circuit 111 - excess heat in the heat generator flow 102 initially increases the heating circuit flow temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$

above the heating circuit target temperature level. It takes a certain amount of time before the mixer 112 is able to set the heating circuit flow temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$

adjust to the target temperature. So there is a heat boost 115 in the heating circuit 111, which is caused by an increase in the heating circuit flow temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$

is marked.

wird auf dem Temperaturniveau von gut 80 °C bis zum Zeitpunkt t2 gehalten, zu dem die Brauchwasser-Isttemperatur ${\vartheta }_{\mathit{WW}}^{\mathit{ist}}$

der gewünschten Brauchwasser-Solltemperatur ${\vartheta }_{\mathit{WW}}^{\mathit{soll}}$

entspricht. Auch dieser Temperaturwert ist nur beispielhaft zu verstehen. Es ist jedoch wünschenswert, dass die Wärmeerzeuger-Vorlauftemperatur ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$

bei der Warmwasserbereitung 121 gegenüber dem Heizbetrieb signifikant erhöht ist, damit das Brauchwasser schnell erwärmt wird. Eine Erhöhung der Wärmeerzeuger-Vorlauftemperatur ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$

gegenüber der Warmwasser-Solltemperatur um beispielsweise 15 K bis 25 K kann durchaus angestrebt sein.The heat generator flow temperature ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$

is kept at the temperature level of a good 80 °C until time t2, at which the actual service water temperature ${\vartheta }_{\mathit{ww}}^{\mathit{is}}$

the required domestic water target temperature ${\vartheta }_{\mathit{ww}}^{\mathit{should}}$

is equivalent to. This temperature value is also only to be understood as an example. However, it is desirable that the heat generator flow temperature ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$

is significantly increased in the hot water preparation 121 compared to the heating mode, so that the hot water is heated quickly. An increase in the heat generator flow temperature ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$

compared to the target hot water temperature by, for example, 15 K to 25 K can definitely be aimed for.

absinkt und sich der Heizkreis-Vorlauftemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$

annähert. Mit anderen Worten kühlt also der Wärmeträger im Vorlauf 102 des Wärmeerzeugers 101 langsam ab. Zum Zeitpunkt t3 beginnt dann wieder der reine (reguläre) Heizbetrieb, d.h. der Heizbetrieb ohne zusätzlichen Wärmeeintrag aus der Warmwasserbereitung 121.At this point in time t2, the heat generator 101 is also switched off, so that the heat generator flow temperature ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$

drops and the heating circuit flow temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$

approaching. In other words, the heat carrier in the flow 102 of the heat generator 101 cools down slowly. It then begins again at time t3 Pure (regular) heating operation, i.e. heating operation without additional heat input from hot water preparation 121.

In figure 4 is the heat output Ẇ for the in figure 3 shown temperature curve reproduced, the heat output is shown separately for hot water preparation and the heating circuit. It can be seen that the heat energy given off during hot water preparation 121 (integrated heat output Ẇ between times t1 and t2; the integrated heat output is also referred to as heat quantity) is about twice as high as the heat energy 116 given off in the heating circuit 111.

After the end of hot water preparation 121 at time t2, the residual heat remaining in the heating system is released as heating energy 117 into the heating circuit 111 before pure heating operation begins again at time t3.

aufgrund der deutlich erhöhten Warmwasserbereitung-Rücklauftemperatur ${\vartheta }_{\mathit{WW}}^{\mathit{RL}}$

so hoch, dass die Effizienzsteigerung der Brennwerttechnologie nicht genutzt werden kann. In den Heizkreis 101 wird somit in dem Zeitraum t1 bis t3 Wärme abgegeben, die ineffektiver erzeugt wurde als im reinen Heizbetrieb.Up to this point in time, however, is the heat generator return temperature ${\vartheta }_{\mathit{WE}}^{\mathit{RL}}$

due to the significantly increased water heating return temperature ${\vartheta }_{\mathit{ww}}^{\mathit{RL}}$

so high that the increase in efficiency of condensing technology cannot be used. In the period t1 to t3, heat is thus released into the heating circuit 101, which heat was generated less effectively than in pure heating operation.

In order to generate more thermal energy at a more effective operating point of the heat generator 101, the invention proposes a method for controlling a heating system, the main features of which are shown in a schematic flowchart accordingly figure 2 are shown. It is pointed out that only the basic ideas of the invention are listed here for the sake of clarity. The optional elements already described can be incorporated into this process flow by those skilled in the art.

um einen vorgegebenen Wert. Durch das Absenken der Heizkreis-Solltemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{soll}}$

schließt der Mischer 112 und koppelt den Heizkreis 111 von dem Wärmeerzeuger 101 ab bzw. vermindert den Durchfluss des Wärmeträgers in dem Heizkreis 111. Dies erfolgt in Verfahrensschritt 53 automatisch.The start 51 of the illustrated method 50 for controlling a heating system is in method step 52 in the detection of a need for hot water preparation and the lowering of the heating circuit setpoint temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{should}}$

by a predetermined value. By lowering the heating circuit target temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{should}}$

the mixer 112 closes and decouples the heating circuit 111 from the heat generator 101 or reduces the flow of the heat transfer medium in the heating circuit 111. This takes place automatically in method step 53.

in Verfahrensschritt 54 erhöht, um das Brauchwasser möglichst schnell auf die Brauchwasser-Solltemperatur ${\vartheta }_{\mathit{WW}}^{\mathit{soll}}$

zu erwärmen. Letzteres erfolgt bei der Warmwasserbereitung in Verfahrensschritt 55.As a result, the heat generator flow temperature ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$

increased in step 54 to the hot water as quickly as possible to the hot water target temperature ${\vartheta }_{\mathit{ww}}^{\mathit{should}}$

to heat. The latter takes place during hot water preparation in method step 55.

wieder auf den regulären Wert, d.h. den Wert vor der Warmwasserbereitung, angehoben. Damit endet das Verfahren in Verfahrensschritt 57.As soon as the hot water has reached the desired temperature, the end of the hot water preparation is recognized in step 56 and the heating circuit setpoint temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{should}}$

raised again to the regular value, ie the value before hot water preparation. The method thus ends in method step 57.

zwischen den Zeitpunkten t1 und t2 während der Warmwasserbereitung. Aufgrund des Schließens des Mischers 112 im Anschluss an das Absenken der Heizkreis-Solltemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{soll}}$

erhöht sich die Heizkreis-Vorlauftemperatur ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$

trotz der Erhöhung der Wärmeerzeuger-Vorlauftemperatur ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$

kaum. Lediglich um ein starkes Abkühlen des Gebäudes zu vermeiden, mischt der Mischer 112 einen kleinen Teil der durch den Wärmeerzeuger 101 erzeugten Wärmeleistung in den Heizkreis 111 ein. Mit dem Ende der Warmwasserbereitung wird der Heizkreis-Sollwert ${\vartheta }_{\mathit{HZ}}^{\mathit{soll}}$

wieder auf das Vorniveau, d.h. den beispielsweise durch eine Heizkurve vorgegebenen regulären Heizkreis-Sollwert ${\vartheta }_{\mathit{HZ}}^{\mathit{soll}}$

angehoben. In dem dargestellten Beispiel wird der Heizkreis-Sollwert ${\vartheta }_{\mathit{HZ}}^{\mathit{soll}}$

um 10 °C abgesenkt, von 50 °C auf 40 °C.The temperature curve resulting from this process accordingly figure 3 is in figure 5 shown. The reduction in the heating circuit set temperature can be seen ${\vartheta }_{\mathit{HZ}}^{\mathit{should}}$

between times t1 and t2 during hot water preparation. Due to the closing of the mixer 112 following the lowering of the heating circuit target temperature ${\vartheta }_{\mathit{HZ}}^{\mathit{should}}$

the heating circuit flow temperature increases ${\vartheta }_{\mathit{HZ}}^{\mathit{VL}}$

despite the increase in the heat generator flow temperature ${\vartheta }_{\mathit{WE}}^{\mathit{VL}}$

barely. The mixer 112 mixes a small portion of the heat output generated by the heat generator 101 into the heating circuit 111 merely to prevent the building from cooling down too much. With the end of hot water preparation, the heating circuit setpoint ${\vartheta }_{\mathit{HZ}}^{\mathit{should}}$

back to the previous level, ie the regular heating circuit set point specified, for example, by a heating curve ${\vartheta }_{\mathit{HZ}}^{\mathit{should}}$

raised. In the example shown, the heating circuit setpoint ${\vartheta }_{\mathit{HZ}}^{\mathit{should}}$

Lowered by 10 °C, from 50 °C to 40 °C.

How figure 6 can be seen, the thermal energy released into the heating circuit 116 during hot water preparation (ie in the period t1 to t2) compared to figure 4 , significantly reduced. As a result, significantly less ineffectively generated thermal energy is fed into the heating circuit 111 .

Reference list:

1

control unit

2

interface

3

interface

4

interface

5

interface

50

Process for controlling a heating system

51

start of the procedure

52

Recognizing the need for hot water preparation and lowering the heating circuit target temperature

100

heating system

101

heat generator

102

Heat generator flow

103

Heat generator return

111

Heating circuit for building heating

112

mixer

113

heating circuit flow

114

heating circuit return

115

heat boost

116

Thermal energy released in the heating circuit during hot water preparation (period t1 to t2)

117

Heat energy given off in the heating circuit after hot water preparation (period t2 to t3)

121

water heating

122

DHW return

Claims (10)

1. A method for controlling a heating system (100) with a heat generator (101), with at least one heating circuit (111) for heating buildings, and with a water heating process (121) for heating service water, wherein a selected heat generator flow temperature (ϑVL/WE) is greater than or equal to the heating circuit target temperature (ϑsoll/HZ), and a mixer (112) for setting a heating circuit flow temperature (ϑVL/HZ) is provided, characterized in that a regular heating circuit target temperature (ϑsoll/HZ) is decreased by a configurable value during the water heating process, and again reset to the regular heating circuit target temperature (^soll/HZ) of the heating operation after the water heating process (121).
2. The method according to claim 1, characterized in that the heating circuit target temperature (^soll/HZ) is reduced before the heat generator flow temperature (ϑVL/WE) is increased during the water heating process (121) .
3. The method according to claim 1 or 2, characterized in that the duration for which the heating circuit target temperature (^soll/HZ) is reduced during the water heating process (121) is limited, and the regular heating circuit target temperature (^soll/HZ) is reset after the duration has expired.
4. The method according to claim 3, characterized in that the duration for which the heating circuit target temperature (^soll/HZ) is reduced is learned from the usual duration of a water heating process (121) in the building by acquiring the duration of the water heating process (121) over a specific period of time and determining an average duration, wherein the selected duration for which the heating circuit target temperature (^soll/HZ) is reduced is a multiple of the determined average duration.
5. The method according to one of the preceding claims, characterized in that the heating circuit return temperature (ϑRL/HZ) is measured and the reduction of the heating circuit target temperature (^soll/HZ) is fed back if the heating circuit return temperature (ϑRL/HZ) exceeds a calorific value limit temperature.
6. A control device for controlling a heating system (100) with a heat generator (101), with at least one heating circuit (111) for heating buildings, and with a water heating process (121) for heating service water, wherein the control device (1) has interfaces (2, 3, 4) for actuating the heat generator (101), the at least one heating circuit (111) and the water heating process (121), and with a computing device, characterized in that the computing device is set up to implement the method according to one of claims 1 to 4.
7. The control device according to claim 6, characterized in that the interfaces (2, 3, 4) can have connected to them temperature sensors for acquiring the heat generator flow temperature (ϑVL/WE), the heat generator return temperature (ϑRL/WE), the heating circuit flow temperature (SVL/HZ), the heating circuit return temperature (ϑRL/HZ), and/or the hot water actual temperature (^ist/WW).
8. The control device according to claim 7, characterized in that a temperature sensor for acquiring the heating circuit return temperature (ϑRL/HZ) is connected to one of the interfaces (2, 3, 4), and the computing device is set up to implement the method according to claim 5.
9. The control device according to claim one of claims 6 to 8, characterized in that the computing device is located in an IT cloud.
10. The control device according to claim one of claims 6 to 8, characterized in that the computing device is located in a central IT system.

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