DK201870692A1 - District heating system and methods for flow control and retrofitting of a flow control system in a district heating system - Google Patents

Abstract

A district heating system, comprising a bypass located between the flow and the return flow from the heat exchanger, and a flow valve located in the bypass, wherein the flow valve is a flow control valve forming part of a flow control system of the district heating system, and wherein the flow control system comprises a first temperature sensor located to measure a temperature in the circulation , an electronic control unit and a battery connected to the control unit for supplying power for operation of the control unit, the control unit comprising means for wireless communication with a communication unit, whereby the control unit can receive data from and thus be remotely controlled from the communication unit and can send data for remote logging to the communication unit and wherein the control unit is configured as a slave unit programmed to periodically request, after a first programmed time interval, a command from the communication unit, which may similarly be configured as a master unit, s after another programmed time interval to send data to the communication device. Methods for flow control and retrofitting of such flow control system in a district heating system.

Description

The invention relates to a district heating system comprising a heat exchanger for transmitting heat energy between a supply side and a user side of the district heating system, a supply to and a return flow on the supply side from the heat exchanger, a bypass located between the flow and the return flow from the heat exchanger and a flow valve located in the bypass.

In existing district heating systems, a fluid, usually a liquid, is heated, but can also be, for example, steam, typically water, in a central plant or plant, for example a cogeneration plant. The heated water is distributed via pipelines in the supply system to the users, which dissipate the heat via a heat exchanger to supply the user's decentralized internal circulation, ie. decreases system. The customer system, for example, for single-family homes can be a single system with few internal strings, or can be a central heating system, which can usually be found in larger buildings or storey buildings, and which can comprise a larger number of strings. Often, both the use water and the water circulated in the internal heating system are heated, for example, for heating the radiators in the building.

Distribution in the district heating system takes place in pipe strings, where there is a significant loss of heat in the heat transport between the plant and the heat exchanger by the user. The heat loss occurs, among other things. as a function of temperature of in particular the flow fluid, viz. flow temperature, a higher temperature resulting in higher heat loss. As a rule, the work is required to supply a certain minimum temperature at the flow to the heat exchanger of the user, and in the optimal situation, ie. in the case of the least possible heat loss, the supply temperature will be or slightly above this minimum temperature.

The heat exchanger of the user is typically part of a heat interface unit (HIU), which thus establishes the interface between the district heating network and the heating system internally of the user. The heat exchanger transfers the heat from the district heating system to the heating system on the user side, ie. decreases system. The HIU is usually located on the user side, for example in an installation cabinet in an installation room in the user building, which is why the district heating plant usually does not have immediate access to the HIU.

Especially for users who are far from the work, ie. where the string to the user is long, or where the user is near or at the end of a string,

DK 2018 70692 A1 is a circulation often located in the district heating system between the flow and the return flow from the heat exchanger. The circulation provides a flow path between the flow and the return flow, thereby ensuring circulation of the district heating fluid even by the most remote users. Particularly during the summer periods, when heat is not used for room heating, but only for hot domestic water, the user's consumption may be so small that the consumption circulation cannot maintain a required minimum temperature of the district heating fluid at the heat exchanger. The circulation can thus be used to ensure a certain minimum temperature, eg 60 ° C, by remote users of the district heating system, even during periods of low consumption. The bypass may be located as part of the HIU and may be located with the user, ie. may also be difficult to access for the district heating plant. In other cases, the bypass is located outside the user side, for example in a well in the road.

Often, a circulation is retrofitted on the basis of a complaint from the user that, in particular, the hot tap water is experienced to have too low a temperature, but a circulation can also be installed in connection with the establishment of the string, especially if it is expected that problems with the supply temperature.

A static flow valve may be arranged in the circulation, which makes it possible to manually control the flow in the circulation and thus the circulation to ensure an appropriate fluid temperature of the user. As a rule, there is no continuous measurement of the flow temperature of the user today, and therefore it can be difficult to ensure an appropriate temperature, especially with the seasonal variations. Since it is difficult and expensive to manually adjust the static flow valve, the valve will often be set so that in the worst possible situation (typically a hot summer day) a sufficiently high flow temperature can be expected from the user. This can mean that the district heating system is often statically oversized via the static flow valve for the flow temperature and in addition is not adjusted or adjusted as required. Therefore, the flow temperature at the heat exchanger will often be far above the required minimum temperature, especially during the summer period. During the winter season, the circulation will often not be needed, but the circulation will nevertheless be operational.

In principle, the static flow valve can be placed in circulation with

Any other circuits and respective static valves are adjusted in accordance with a required minimum temperature. However, it can be difficult and cumbersome to provide effective balancing in this way, especially because the valve has to be manually adjusted and can be difficult to access, including being located on the user side, and therefore today's utilities often have difficulty both in ensuring a required minimum temperature of flow and to ensure that the temperature is not too high. Often, the valve is set only when retrofitting the circulation or when installing a new district heating string and thus in such a way that the utility company ensures the minimum temperature regardless of variations in the need, ie. this often results in an oversize of the heat supply to the user.

In existing district heating systems, therefore, there is often a significant heat energy waste in connection with the mentioned circuits.

Ca. 64% or approx. 1.7 million of the Danish households are equipped with district heating, and there are more than 60,000 km of pipes in the Danish district heating network. Thus, already a considerable number of these orbits already exist today.

An object of the invention is therefore to improve the energy efficiency of a district heating system as mentioned in the introduction.

According to the invention, this and / or other objects of a first aspect of the invention can be countered with a district heating system according to the preamble above, wherein the flow valve is particular in that it is a flow control valve forming part of a flow control system of the district heating system, wherein the flow control system comprises:

- a first temperature sensor located to measure a temperature in the circulation,

- an electronic control unit and

- a battery connected to the control unit for supplying power for operation of the control unit,

- where the control unit can receive measured temperature data from the temperature sensor and can set an opening degree of the flow control valve, where the control unit comprises means for wireless communication with

DK 2018 70692 A1 is a communication device whereby the control unit can receive data from and thus be remotely controlled from the communication unit and can send data for remote logging to the communication unit, and wherein the control unit is arranged as a slave unit which is programmed to periodically request a first programmed time interval. command from the communication unit, which may similarly be configured as a master unit, and to periodically transmit data to the communication unit after another programmed time interval.

The invention thus provides a district heating system with a circulation where it is possible to control the flow control valve automatically and dynamically. This means that it is possible to control the valve and thus the flow through the circulation as needed, ie. so that a temperature is maintained in the flow at or slightly above the required minimum temperature. If the temperature is too low, the control unit will adjust the valve to a greater degree of opening and thus a greater flow through the circulation, after which the flow temperature will rise. Conversely, if the temperature is too high, the control unit will adjust the valve to a smaller opening degree and thus a smaller flow, after which the flow temperature will decrease. The temperature can be measured continuously or periodically according to certain time intervals, so that it will be possible to continuously adjust the valve and thus the flow temperature. The control unit may thus be arranged to make a dynamic regulation of the flow through the circulation as a function of the temperature measured in the circulation.

The inventors of the present invention have realized that control systems with such a control unit and flow control valve are usually energy intensive and therefore must be expected to be connected to existing power supply, in particular from the user, which can be cumbersome and may also mean that the supply does not have full control over control of the system as the power to the system can be shorted.

It has thus been appreciated that the invention provides a remote-controlled, battery-operated system that can be used with appropriate control and current battery technology (e.g., four lithium AA batteries, ER14505) for up to five years or more, before the battery must be replaced. In addition, it has become

DK 2018 70692 A1 realized that installing a system according to the invention can give savings that often and for many existing circulations will have a very short payback time due to large savings on the heat loss on the supply side.

Low energy consumption can be achieved by controlling the controller as a slave unit programmed periodically after a first programmed time interval, requesting a command from the communication unit similarly configured as a master unit, and periodically sending a second programmed time interval to communication device. Thus, the means of the wireless device for wireless communication, which would normally, for example in a wifi network, will have a relatively high power consumption, be dormant when data is not being sent or received. Therefore, energy consumption will be a fraction of the consumption in a system where these funds are always active. Thus, it has also been appreciated that periodic communication with relatively long periods of time may advantageously be used in the system of the invention.

The district heating system according to the invention and in particular the flow control system may be located at the end of a district heating string. The district heating system may further comprise several pipe strings and also the district heating plant itself from which the hot fluid is delivered.

Thus, in the interval between the request for a command or the transmission of data, the wireless device's means for wireless communication may be passive or switched off and thus may have an energy consumption near or near zero. Thus, the means of wireless communication may be arranged such that it is not possible to '' wake up 'the control unit by means of communication from the communication unit, ie. so-called push commands are not possible.

Since the control unit does not need to connect to an external power supply, such as a power circuit of the user, the district heating plant can be ensured full control over the operation of the system.

Thus, with the district heating system according to the invention, a dynamic or periodic control of the flow in the circulation is made possible by the flow control valve. The control unit also enables wireless control of the control unit, whereby it is possible to set the control unit to control the flow in circulation.

DK 2018 70692 A1, for example, refers to a user profile that the control unit can be supplied via the communication device and which can be stored in a memory of the control unit. The periodic transmission and reception of data from the control unit means that the energy consumption for operating the means of wireless communication can be kept very low. In addition, the controller may be arranged to communicate data to the communication device which may trigger an alarm for a deviation profile which may be part of the user profile used. Deviations may in particular be ifm. relevant measurements of pressure and temperature of sensors located relevant places in the system. Possibly. For example, the communication device or cloud (see further below) may be arranged to forward the alarm to another communication device, for example in the form of a text message sent to a mobile phone.

Using such means for wireless communication can achieve such great savings in the energy consumption of the agents that it is possible to provide a district heating system according to the invention which can be operated inexpensively and efficiently with a conventional or limited capacity ordinary battery or battery system. to replace, for example, two or four AA batteries. Calculations show that replacing four AA batteries that form the battery for the controller can thus be expected to last for at least five years, which is considered more than acceptable for the utility company. The batteries can be replaced with ordinary maintenance.

Thus, the invention provides a practically usable district heating system whereby the heat loss associated with circulation in district heating systems is reduced, since the flow through the circulation can be controlled according to the circumstances. In addition, pump energy can be saved, as the pump power will usually be less when the flow control valve is adjusted to a lower flow through the circulation as appropriate. A smaller flow through the circulation can also lead to less wear of both pump and pipe systems on the supply side, as average pump pressure can be reduced accordingly.

The flow control system may further comprise an actuator connected to or mounted on the flow control valve to provide the change in the degree of opening of the flow control valve and thus the flow through the valve and thus the circulation. The actuator may have a stroke, one

DK 2018 70692 A1 stroke length of the flow control valve may be arranged according to the actuator stroke length.

The motor of the actuator can advantageously be driven by the same battery as the control unit, for which purpose a live connection can be provided between the battery and the actuator. Using a relatively small stroke actuator and valve, it has been calculated that a battery of four AA batteries may continue to have the capacity to operate both the actuator and control unit for more than five years in most cases and in some cases for up to ten years or more. This applies to a receiving interval of the control unit of 6 hours and a transmitting interval of 15 minutes, considering these examples or similar intervals to be suitable for the purpose.

Battery life depends on the selected user profile, which affects how often the actuator is activated. In an example of a user profile, the control unit will be programmed such that the actuator only closes the flow control valve in connection with switching between summer and winter and opens only when switching between winter and summer. Even with such a simple user profile, a considerable amount of both heat energy and pump energy can be saved.

Alternatively, the actuator may be operated by a separate battery, in which case the battery may be located at, in or may form part of the actuator. This may have the disadvantage that the battery for the actuator will then have to be replaced separately, and in some cases the flow control valve will be difficult to access, for example in a well. By contrast, the control unit or a box with the control unit can often be placed more easily accessible, for example in an installation cabinet of the user, and it will therefore be easier to replace the battery.

The control unit may be arranged for any. periodically measuring the life of the battery, eg by measuring the capacity or voltage, and possibly sending this information to the communication unit, thereby allowing the communication unit to be alerted in good time that a change of battery is necessary.

The control unit may also be set to set the flow control valve in a predetermined setting, ie. with a predetermined opening area, for example fully open, when the battery life is measured to be near zero, after which flow in the circulation may be present, and a required minimum temperature in the flow

GB 2018 70692 A1 can be secured even when the battery is exhausted.

The flow control system may also be arranged such that the battery supplies other parts of the system, including, for example, the temperature sensor and / or one or more other sensors.

The communication device can be, for example, a PC, a smart phone or a tablet computer, which can have an internet connection for the cloud, the controller being arranged for connection with the cloud, cf. also more about connection with the cloud below. In any case, it is preferred that the control unit can be accessed via an electronic interface (e.g. web, app or API), in which a code can sit in particular on the system, in particular on or at the control unit, where the communication unit with the code can identify the system and / or in in case of retrofitting the system may suggest a mounting point for the system. It is further preferred that, possibly. via the interface, an alarm limit value can be encoded in the flow control system, the communication unit or the cloud for one or more of the values measured with one or more of the sensors in the system, and where an alarm can be communicated to the communication unit when an alarm limit value is reached.

The flow control system may further comprise a first pressure sensor located for measuring a plant pressure, the first pressure sensor being connected to the control unit so that the control unit can detect the system pressure. The plant pressure is the supply pressure on the supply side. The first pressure sensor may advantageously be located in the outlet side or the return flow from the flow control valve, but alternatively may be located elsewhere where the pressure represents the plant pressure. This makes it possible to identify a conduit break, which is particularly evident in the relatively large pressure drop in the plant pressure. Often, a suitable flow control valve comprises an access to measure the outlet pressure within the valve itself, for example in the form of a PT port, and the first pressure sensor may advantageously be a PT plug inserted here. The measurement of the temperature via the first temperature sensor can similarly be done here, since the temperature sensor can be part of the PT plug.

In addition, temperature sensors can be mounted in the flow and return flow from

GB 2018 70692 A1 the heat exchanger and measurement data can be transferred to the control unit, whereby the temperature drop across the heat exchanger can be monitored and the system can be set to achieve an optimal or improved (typically higher) temperature drop over the heat exchanger, thereby saving additional heat energy. The sensor in the flow may be the same sensor as the first temperature sensor, the temperature of the circulation usually being nearly identical to the temperature in the flow to the heat exchanger.

The flow control system may further comprise pressure sensors located for measuring a differential pressure across the flow control valve, these pressure sensors being connected to the control unit such that the control unit can detect the differential pressure and communicate this to the communication unit, after which the pump pressure can be used to set the pump pressure to a necessary minimum level via the data from the communication unit. on the supply side. This allows further reduction of pumped energy consumption and wear of the pump.

One or more or all of the aforementioned sensors in the district heating system are preferably digital and passive when not measured, thereby further extending the life of the battery.

Preferably, the control unit can be coded or set via the communication unit with a suitable or customized user profile, which can be selected automatically or manually according to circumstances. For example, a profile may be for seasonal management such as summer / winter operation or may be day controlled, for example, taking into account capacity constraints or the like, which may vary over the day.

One or more components of the flow control system and in particular the control unit may be located in a control or control box, and there may be one or more outputs from the flow control valve box, sensors, battery pack etc. Alternatively, the battery may be located inside the box. The box may be provided with a display or screen where it may be possible to display, for example, one or more measurements from one or more sensors of the flow control system and where it may be possible to set the control unit. The box can form part of the user's HUI and can be placed in an installation cabinet

DK 2018 70692 A1 or similar. The bypass and / or flow control valve may also be arranged as part of the HUI or may be located in circulation, for example, in the road. The connection or connections between the control unit and the actuator for transmitting measured data and / or for setting the actuator from the flow control unit may be in the form of wires and / or may be wireless. In the latter case, the flow control valve and / or one or more sensors may be powered by separate batteries and may comprise means for transmitting and receiving data wirelessly, for example at the same intervals as in the corresponding means in the control unit, for wireless communication with the communication unit, where these means can also communicate with the flow control valve and / or the one or more sensors.

The flow control system may be retrofitted to an existing district heating system, in which case a static flow valve may have been replaced with the flow control system.

The battery may be a lithium battery, may comprise one or more cells and may have a voltage of less than 10, 8, 6, 5 or 4 V, such as a 3.6V LiSOCl2 battery. Calculations show that such a battery can lose less than 1% of its capacity per year over 10 years with one sensor fitted. When using user profiles, the battery life can be reduced, but with the user profiles considered to be relevant, a battery life of more than five years can be expected with a system according to the invention, in which both control unit, sensors and actuator are supplied with battery power, and wherein the battery comprises 4 AA batteries. The individual batteries in the battery may be assembled in a battery pack with a plug connected to the control box, or the batteries may be located inside the control box.

One or more sensors may generally be mounted in integrated ports of the valve, for example, the valve may comprise one or two so-called pressure (temperature / pressure) ports, in which one or respectively (pressure / temperature) plugs are located.

The flow control valve may be of the type PICV (pressure independent control valve), in particular where the valve comprises an automatic and / or dynamic control of a differential pressure over the flow control valve, e.g.

DK 2018 70692 A1 described in applicant's WO / 2006/136158 A1, in particular a Frese® Optima® valve, or in WO 2009/135490 A2, in particular a Frese® Optima Compact® valve. The valve may be modified to have a smaller stroke.

In principle, the flow control system in one embodiment of the flow control system according to the first aspect of the invention, where such an embodiment is outside the scope of the present invention as defined in the present claims, may be designed without the feature that the control unit comprises means for wireless communication with a communication unit. , whereby the control unit can receive data from, and thus be remotely controlled from, the communication unit and can transmit data for remote logging to the communication unit, and / or without the feature that the control unit is arranged as a slave unit for the communication unit, which is similarly arranged as a master unit. In addition, for the latter feature, where the control unit is arranged as a slave unit for the communication unit, which is similarly arranged as a master unit, the flow control system may be without the feature that the control unit is programmed to periodically request a command from the communication unit and periodically after another programmed time interval to send data to the communication device. Thus, for example, the controller may be controlled via a WiFi network or via a wired connection.

Alternatively, a district heating system may be referred to as a district heating installation and, as used in the present application, is a system in which a fluid is heated or cooled in a central plant or plant, e.g., a cogeneration plant, and the heated fluid on the supply side is distributed to multiple users. which dissipates heat (in the case of heated fluid) or emits heat (in the case of cooled fluid) for heat supply or heat removal of a user take-off system. The fluid on the supply side will therefore usually be separated from the fluid on the supply side, since the heat energy can be transferred by means of a heat exchanger. Thus, the term district heating system also includes district cooling systems, and wherever in this specification reference is made to the generation of heat or the like, it should be understood that heat reception may be in the case of a district cooling system.

DK 2018 70692 A1

A heat interface unit (HIU), as used in the present application, establishes the interface with the user's pantry system and typically comprises a heat exchanger which transfers heat from the supply side to the pantry system.

A bypass in the district heating system as used in the present application is located near or immediately before the heat exchanger between the flow and the return flow from the heat exchanger or HIU, thus providing a flow path between the flow and the return flow. Such a circulation can be used to ensure a certain minimum flow temperature of, for example, 60 ° C for remote users of the district heating system.

A flow control valve is, as used in the present application, a valve by which it is possible to control automatically or non-manually, typically by means of an actuator, a flow through the valve. In contrast, a static flow valve is a valve that is manually adjusted, for example, by turning on a handle.

An actuator to which the term is used in the present application is a unit comprising a motor which can adjust a valve, i.e. can move a valve element when the actuator is connected to a valve. An actuator can usually be connected to a control to drive the motor and thus control the setting of a valve element of the valve. An actuator may be a linear actuator which is preferred according to the present invention, in which the motor can move a valve member of the valve linearly. Alternative actuators can be used, including actuators, where the motor can move a valve element, for example in a circular direction.

The stroke length of a valve or actuator is, as used in the present application, the length at which the actuator can move a valve element of the valve between two outer positions, for example a fully open and a fully closed position. If the stroke length is smaller, less energy should usually be used to move the valve between the two outer positions.

A control unit as used in the present application is an electronic device which can be used to control or regulate a flow control valve. The controller may comprise a memory in which one or

Multiple user profiles can potentially be stored. It may also include one or more printed circuit board (PCBs) and connections to the individual components of the device. One skilled in the art will know how to make a suitable control unit for the purpose, and the individual components such as antenna are available in the market.

An opening degree or opening area of a valve as used in the present application denotes the size of a flow opening through the valve and is an expression of the flow which will flow through the valve and thus the circulation at a given pump or system pressure.

A sensor used in the term in the present application may also be referred to as a sensor, may be electronic, and may measure, for example, a pressure or temperature of a fluid such as the fluid in the supply side or in connection with the flow control valve. This may, for example, be a PT plug, which can measure both temperature and pressure, and is often used in connection with flow control valves, especially located in PT ports of the valves.

Wireless means of communication as used in the present application may comprise one or more PCBs, such as network cards, as well as one or more antennas, and may enable electronic wireless communication with an electronic receiver in the form of a communication device.

A battery used in the term of the present application is an electrical component which contains stored energy and makes the energy available to appliances connected to it in electrical form. A battery may include several sub-batteries or cells which may be interconnected. Alternatively, a battery may be referred to as an element. Any suitable type of battery may be used as the battery of the present invention, including particularly electrochemical batteries such as lithium or Li batteries. A battery may be rechargeable.

A slave unit and a master unit, as the terms used in the present application, are the components of a system which follows the master / slave communication model known to those skilled in the art, i.e. a model in which a master device, e.g., the communication unit, has one-way control with one or more slave devices, e.g., the control unit. The communication unit in the district heating system according to the invention may be for control of only the control unit

DK 2018 70692 A1 in the district heating system according to the invention or also to control both the control unit and one or more identical, similar or other units.

In one embodiment of the district heating system according to the invention, the change in the opening degree of the flow control valve is provided by an actuator motor in an actuator, where the actuator motor is supplied from the battery.

See above for a discussion of potential benefits associated with this.

In one embodiment, the means of wireless communication is arranged or programmed to receive data in a time window which is opened at a time interval of 1-120 minutes, 2-60 minutes, 5-30 minutes or 10-20 minutes, e.g. 15 minutes, and / or to send data at a time interval of ¹ Λ -12 hours, 2-10 hours, 3-9 hours, 4-8 hours or 5-7 hours, eg about 6 hours.

For example, the time window for receiving data may be 5, 10, 20, 30 or 60 seconds.

In one embodiment, the control unit is arranged for wireless communication with the communication unit via an LPWAN-type network.

The LPWAN network type is also referred to as low-power wide-area network, LPWA network, LPN or low power network and is preferably of the ultra-narrow band subtype or UNB LPWAN, in particular the Sigfox network, which is widespread throughout much of the world, including Denmark.

LPWAN is a type of wireless telecommunication network designed for long-range communication at low bitrate between things or objects such as sensors powered by a battery. LPWAN differs from wireless WAN, which is designed to transfer larger amounts of data between users, which consumes more power. The LPWAN data rate typically varies between 0.3 kbit / s to 50 kbit / s per channel. Preferably, in the present invention, LPWAN is provided through a third party, i.e. neither by the supply nor by the user, in particular as by or by the Sigfox network.

Other existing UNB LPWAN types include Telensa, Nwave, Weightless, and NbFi protocol. Other LPWAN types include DASH7, LTEMEC, MySensors, NB-IoT, RPMA and Taggle Byron.

It has been realized in the context of the present invention that

DK 2018 70692 A1

LPWAN is particularly suitable for use in the control unit's communication with the communication unit, since the low bitrates, the low energy consumption, the periodic communication of data and the master / slave model result in a very low energy consumption in connection with the wireless communication, which enables realizing a practically usable, battery operated district heating system according to the invention.

In one embodiment, data is provided from the controller to the communication device and / or commands from the communication device to the controller via a cloud service.

Hereby a communication point is inserted in the form of the cloud between the communication unit and the control unit in the form of a data collection in the "cloud" or "the cloud". When data is transferred from the control unit, for example via LPWAN, to a data collection in the cloud, the communication device, for example via the Internet, will be able to send a command to the cloud at any time and the control unit can request the cloud at any time and (possibly with a delay) receive the command from the cloud. Similarly, the controller can send data to the cloud at the aforementioned time interval, and the communication device can retrieve the data in a possible time. later appropriate time when the communication device establishes a connection with the cloud.

In one embodiment, the actuator remains in substantially the same position when no voltage is applied.

Hereby it can be achieved that the actuator must be supplied with a minimal amount of current over time, the actuator's power consumption being or may be near zero when the actuator is not operating to adjust the flow control valve. This also enables the said embodiment, in which the actuator is also supplied with power from the battery in the system, thus obtaining a life of the battery of more than five years.

This can be achieved, for example, by using a three-point actuator, which is an actuator that moves at volts over time, ie. if there is voltage on the actuator for eg 20 seconds, the actuator moves, for example, 1.3 mm and stands still in that position without the use of external energy. In contrast, for example, a 0-10 V modulating actuator always has a control voltage of, for example, 4.3 V to determine

GB 2018 70692 A1 actuator setting in relation to the stroke length of the valve.

In one embodiment, the stroke length of the valve and / or actuator is less than 10, 5, 4 or 3 mm, e.g., 2.5 mm.

In connection with the invention, it has been realized that such a small stroke of the valve / actuator can be used, since precise adjustment of the flow control system will usually not be a requirement in normal operation of the system. The smaller stroke can thus cause the actuator motor to consume less power when adjusting the valve, which in turn can extend the life of the battery, in the case where the actuator is powered from the battery.

In one embodiment, the district heating system further comprises a second flow control valve mounted in the flow to or the return flow from a heat exchanger between a supply side and a discharge side of the district heating system, where the second flow control valve is connected to the control unit of the flow control system or another electronic control unit, the flow control valve. an opening degree of the second flow control valve and comprises means for wireless communication with a communication unit, potentially the same communication unit as that of the control unit of the flow control system, whereby the control unit of the second flow control valve can receive data from and thus be remotely operated from the communication unit.

Thus, it may be possible to switch off the heat of a user via the communication unit wirelessly and remotely, for example in connection with non-payment. Today, it is often the case that the work must have access to the property by the user in order to shut down the heat, which can be inconvenient and costly, especially in cases where the authorities need to be involved.

The second flow control valve and associated control unit may be part of a flow control system which is identical to or similar to the flow control system with the first flow control valve. Hereby the same type of flow control system can be used for both purposes. This second flow control system may include one or more of its options

DK 2018 70692 A1 first flow control system mentioned above, just as one or more of the components herein can be used in both flow control systems.

Thus, the second flow control valve and the associated control unit can be retrofitted or mounted in connection with the installation of a new system.

The second flow control valve and the associated control unit can each be according to any of the embodiments mentioned for the first flow control valve and its associated control unit. Below, for example, the second flow control valve may be one connected to an actuator which may be located and arranged as explained above in connection with the first flow control valve.

The control unit associated with the second flow control valve may be connected to a temperature sensor located in the heat exchanger flow and / or a temperature sensor located in the return flow from the heat exchanger. The control unit associated with the second flow control valve may be arranged to adjust the second flow control valve on the basis of a difference between the measured temperatures, possibly by means of temperature data from these two temperature sensors. in conjunction with a cooling profile stored in a memory of the control unit associated with the second flow control valve. In this way, a suitable cooling of the district heating fluid can be obtained, thereby further saving heat energy.

The one or both sensors may also comprise pressure measurement and may be PT plugs, and the control unit associated with the second flow control valve may potentially be arranged to receive pressure measurement from one or both of the pressure sensors.

The control unit associated with the second flow control valve may be arranged to monitor pressure measurement from a pressure sensor located in the return flow from the heat exchanger and may also be arranged to detect rapid and / or large drop in pressure in the return flow which will correspond to the plant pressure in the district heating system and potentially transmit an alarm to the communication device. In this way, breakages of the system can be quickly detected.

DK 2018 70692 A1

Alternatively or additionally, the plant pressure can be measured and / or monitored via a pressure sensor in the return flow from the first flow control valve, potentially via a sensor in the valve itself, eg a PT plug.

In another invention which is not within the scope of the present invention, the present embodiment (i.e., the embodiment described just above comprising the second control valve) in one or more of the above alternatives may be implemented as part of a district heating system according to the invention, but as is designed without the flow control system.

Another aspect of the invention involves a method of flow control of a flow control system according to any one of the preceding claims, wherein the method comprises the steps of:

providing a flow control system according to any of the preceding claims, that a temperature measurement from the temperature sensor is communicated to the control unit, and that the control unit automatically adjusts the flow control valve after the temperature measurement.

The controller's setting of the flow control valve may be based on a user profile stored in a memory of the controller and which the controller may be provided from the communication device.

The control unit's setting of the flow control valve may be via a signal sent from the control unit to an actuator of the flow control valve, potentially via a line.

In one embodiment of this method for flow control of the district heating system according to the embodiment above, wherein a second flow control valve is mounted in the flow to or the return flow from a heat exchanger between a supply side and a discharge side of the district heating system, where the other flow control valve is connected to the control unit of a flow control system. control unit, wherein the control unit of the second flow control valve can set an opening degree of the second flow control valve and comprises means for wireless communication with a communication

DK 2018 70692 A1 cation unit, potentially the same communication unit as for the control unit of the flow control system, whereby the control unit of the second flow control valve can receive data from and thus be remotely operated from the communication unit, the method comprises the control unit associated with the second flow control valve adapted to monitor pressure measurement from a pressure sensor located in the return flow from the heat exchanger and to detect drop in pressure in the return flow which will correspond to the system pressure in the district heating system and potentially send data to the communication unit that may trigger an alarm.

In a third aspect, the invention involves a method for retrofitting a flow control system in a district heating system, the method comprising the steps of:

providing an existing district heating system which comprises

- a heat exchanger for the transmission of heat energy between a supply side and a user side of the district heating system,

- a supply to and a return flow on the supply side from the heat exchanger,

a bypass located between the flow and the return flow from the heat exchanger and

- a static valve located in the circulation, the method being particular by further comprising the steps of:

disassembling the static valve and retrofitting a flow control system to replace the static valve comprising the flow control system

a flow control valve forming part of a flow control system of the district heating system,

- a first temperature sensor positioned to measure a temperature in circulation,

an electronic control unit, which can receive measured temperature data from the temperature sensor and can set an opening degree of the flow control valve, the control unit comprising means for wireless communication with a communication unit, wherein

DK 2018 70692 A1 at the control unit can receive data from, and thus be remotely controlled from, the communication unit and can send data for remote logging to the communication unit, where the control unit is arranged as a slave unit which is programmed to periodically request a command from the communication unit after a first programmed time interval. which may similarly be configured as a master device and to periodically transmit data to the communication device periodically after another programmed time interval, and

- a battery connected to the control unit for supplying power for operation of the control unit,

- so that the control unit can set an opening degree of the flow control valve for controlling a flow through the bypass.

The flow control system established by this method can be according to any of the above embodiments of the flow control system according to the invention.

A detailed embodiment of the invention will be described in detail below with reference to the drawing, in which: FIG. 1 shows a flow diagram of a known district heating system, and FIG. 2 shows a corresponding flow diagram modified for an embodiment of the district heating system of the present invention.

FIG. 1 shows a flow diagram for a known district heating system. Only one end of a single pipe string is shown, and before the string end shown, several strings are present, one pump 1 being connected to more or all of these strings.

The district heating system of FIG. 1 comprises a heat exchanger (not shown) located in a HUI 2 for transmitting heat energy between a supply side (to the left of HUI 2) and a user side (not shown, but to the right of HIU 2)) of the district heating system, an inlet 3 to and a return inlet 4 on the supply side from HIU 2, an inlet 5 located between the inlet 3 and the return inlet 4 from HIU 2, and a flow valve 6 located in the inlet 5.

In operation, water is heated in a central cogeneration plant (not shown) which includes the pump 1. The heated water is distributed via pipe strings (not shown) in

DK 2018 70692 A1 supply system for the shown end-string, which takes the heat through the heat exchanger in HIU 2 for supplying the user's decentralized internal circulation, ie. the take-off system, which is located to the right of HIU in the figure.

The heat exchanger is part of HIU 2, thus establishing the interface between the district heating network and the heating system internally of the user. The heat exchanger transfers the heat from the district heating system to the heating system on the user side, ie. decreases system. The HIU is located on the user side, for example in an installation cabinet in an installation room in the user building.

The circulation 5 provides a flow path between the flow 3 and the return flow 4, thereby ensuring circulation of the district heating water near HIU 2. The circulation is used to ensure a minimum temperature of, for example, 60 ° C the user, even during periods of low consumption. The circulation here is not placed as part of the HIU, but outside the user side, eg in a well in the road.

A static flow valve 6 is arranged in the circulation, whereby it is possible to manually control the flow in the circulation and thus the circulation to ensure an appropriate fluid temperature of the user. No continuous measurement of the flow temperature of the user is made, and the valve is set so that in the worst possible situation (typically a hot summer day) a sufficiently high flow temperature can be expected for the user.

The bypass 5 comprises a flow 7 to and a return flow 8 from the valve 6.

The district heating system of FIG. 1 further comprises a second static valve 9 in the flow 3, more specifically in the part 3a between the flow 7 to the circulation 5 and HIU 2 and a third static valve 10 in the return flow 4, more specifically in the part 4a between HIU 2 and the return flow 8 from the circulation 5. This makes it possible to manually set or close the flow in the inlet 3a and the return inlet 4a respectively from the heat exchanger in HIU 2.

FIG. 2 shows a corresponding flow diagram modified for an embodiment of the district heating system of the present invention. The same reference numerals as in FIG. 1 is used in FIG. 2 for corresponding elements.

In FIG. 2 is the static valve 6 of FIG. 1 replaced with a flow control system 11 to provide a district heating system according to the invention. Thus, FlowRedk 2018 70692 A1 gelation system 11 is mounted in an embodiment of the method according to the third aspect of the invention, the static valve 6 of FIG. 1 has been first dismounted and the retrofitting of the flow control system replaces the static valve 6.

The flow control system 11 comprises a flow control valve 12, two temperature and pressure sensors in the form of PT plugs at 13, 14 inserted in the valve 11 and thus located to measure the temperature and pressure in the inlet 7 to and the return inlet 8 from the inlet 5 respectively.

The flow control system 11 further comprises a control box 15 in which is provided an electronic control unit (not shown) and an internal battery (not shown) connected to the control unit for supplying power for operation of the control unit. The control unit can receive measured temperature and pressure data from the sensor via wires, respectively 16, 17, and can set an opening degree of the flow control valve and thus the flow of district heating water through the valve 12, the actual flow also being dependent on a differential pressure across the valve.

The controller comprises means (not shown) for wireless communication with a communication device (not shown), whereby the controller can receive data from, and thus be remotely operated from, the communication unit and can send data for remote logging to the communication unit. The controller is configured as a slave unit which is programmed to periodically request a command from the communication unit periodically after a first programmed time interval, which may similarly be configured as a master unit, and to periodically transmit data to the communication unit after a second programmed time interval.

Thus, it is possible through the control unit to regulate the flow control valve 12 automatically and dynamically, and it is possible to control the valve 12 and thus the flow through the circulation as needed, ie. so that a temperature is maintained in the flow at or slightly above the required minimum temperature. If the temperature is too low, the control unit will adjust the valve to a greater degree of opening and thus a greater flow through the circulation, after which the flow temperature will rise. If the temperature is too high, the control unit will reverse the valve

DK 2018 70692 A1 a smaller opening degree and thus a smaller flow, after which the flow temperature will decrease. The temperature can be measured continuously or periodically according to certain time intervals, so that it will be possible to continuously adjust the valve and thus the flow temperature. The control unit is arranged to dynamically control the flow through the circulation 5 as a function of the temperature measured in the circulation 5.

The battery includes a battery pack with four Lithium AA batteries, 3.6V ER145050.

In the interval between the request for a command or the transmission of data, respectively, the wireless device's means of wireless communication are passive or switched off and thus have an energy consumption close to or at zero. The means of wireless communication are further arranged such that it is not possible to '' wake up 'the control unit by means of communication from the communication unit, ie. so-called push commands are not possible.

As the control unit is not connected to an external power supply, the district heating plant ensures complete control over the operation of the system.

The control unit further enables wireless control of the control unit, whereby it is possible to set the control unit to control the flow in circulation according to a user profile, which the control unit is supplied with via the communication unit and which is stored in a memory of the control unit. The control unit is further arranged to communicate data to the communication unit which may trigger an alarm after a deviation profile which is part of the user profile used. More specifically, the deviations are deviations from defined pressure and temperatures of the sensors 13, 14 in the valve 12.

The flow control system further comprises an actuator 18 mounted on the flow control valve 12 to provide a suitable change in the opening degree of the flow control valve 12 and thus the flow through the valve 12 and thus the bypass 5. The actuator 18 is a linear actuator with stroke and a stroke of the flow control valve 12 is arranged according to the actuator stroke length.

The motor M of the actuator is powered by the same battery as the control unit, for this purpose providing a live connection 19 between

The connection 19 also comprises wires for controlling the motor by means of the control unit.

The controller is set to a receive interval of 6 hours and a transmit interval of 15 minutes.

The control unit is further arranged to periodically measure the life of the battery by measuring the battery voltage and sending this information to the communication unit. The controller is also set to set the flow control valve to a fully open position when the battery life is measured to be near zero.

The flow control system is also arranged such that the battery supplies the sensors 13, 14 via wires in the connections 16, 17.

The communication unit is a smart phone that has an internet connection for the cloud, the control unit being arranged for connection with the cloud, cf. also more about connection with the cloud below. The communication unit can be accessed via a mobile app and there is a code on the box 15, where supplying the communication unit with the code can identify the system and / or in case of retrofitting the system may suggest a mounting location for the system. In addition, via the app an alarm limit value can be encoded in the flow control system for one or more of the values measured with the sensors 13, 14, where an alarm can be communicated to the communication unit when an alarm limit value is reached.

The sensor 14 is located for measuring a system pressure in the district heating system, the sensor 14 being connected to the control unit so that the control unit can detect the system pressure.

In other embodiments, temperature sensors may also be mounted in feed 3 and return 4 from the heat exchanger in HIU 2, and measurement data can be transmitted to the control unit whereby the temperature drop across the heat exchanger can be monitored and the system can be set to achieve an optimal or improved (typically higher) temperature drop. over the heat exchanger. The sensor in the flow 3 could here be the sensor 13, the temperature in the circulation 5.

The flow control system may further comprise pressure sensors located

DK 2018 70692 A1 for measuring a differential pressure across the flow control valve, these pressure sensors being connected to the control unit, so that the control unit can detect the differential pressure and communicate this to the communication unit, whereupon the pump pressure via the data from the communication unit can be used to set the pump pressure to a necessary minimum level on the supply side. .

The controller can be coded or set via the communication device with a suitable or customized user profile, which can be selected automatically or manually according to circumstances. For example, a profile may be for seasonal management such as summer / winter operation or may be day controlled, for example, taking into account capacity constraints or the like, which may vary over the day.

The box 15 is provided with a display where it is possible to show the measurements the sensors 13, 14 of the flow control system and where it is possible to set the control unit, for example for selecting a user profile.

The individual batteries in the battery are assembled in a battery pack in box 15. The flow control valve 12 is of the type PICV (pressure independent control valve), in particular in applicant's WO 2009/135490 A2, in particular a Frese® Optima Compact® valve. The valve is modified to have a smaller stroke than usual.

The controller includes a memory (not shown) where one or more user profiles potentially and measured data can be stored. It also includes a PCB for control and connections to the individual components of the device (not shown).

The wireless means of communication also comprise one or more PCBs, a network card, and an antenna for communication with the communication device, enabling electronic, wireless communication with the communication device.

The time window for receiving data for the controller is 10 seconds.

The control unit is further arranged for wireless communication with the communication unit via an LPWAN-type network, in particular the Sigfox network. Data from the controller is supplied to the communication device and / or

DK 2018 70692 A1 commands from the communication unit to the control unit via a cloud service. When data via the Sigfox network is transferred from the control unit to cloud data collection, the communication device can send an order to the cloud at any time via the Internet, and the control unit can query the cloud at any time and (possibly with a delay) receive the command from the cloud. Similarly, the controller can send data to the cloud at the aforementioned time interval, and the communication device can retrieve the data in a possible time. later appropriate time when the communication device establishes a connection with the cloud.

The actuator 15 remains in substantially the same position when no voltage is applied. This is achieved by using a three-point actuator.

The stroke of the valve 12 and the actuator 15 is 2.5 mm.

The district heating system comprises in the embodiment shown in FIG. 2 shows another flow control valve 20 mounted in the return flow 4 from the heat exchanger. The second flow control valve 20 is connected to another electronic control unit. The controller sets an opening degree of the second flow control valve 20 and comprises corresponding means of wireless communication with the communication unit, whereby the control unit can correspondingly receive data from and thus be remotely operated from the communication unit.

This makes it possible, via the communication unit, to wirelessly and remotely shut down the heat of a user, for example in connection with non-payment.

The second flow control valve 20 and the associated control unit comprise a control box 21, which in its content and appearance is identical to the control box 15. Similarly, a corresponding actuator 22 is mounted on the second flow control valve 20.

The second flow control valve 20 and the associated control unit 21 are similarly retrofitted in the district heating system shown in FIG. 1, in particular, the second flow control valve 20 is mounted in the return flow 4 after the string member 4a and the static valve 10.

The control unit associated with the second flow control valve 20 is connected to a temperature sensor 23 located in the inlet 3 to the heat exchanger after the inlet 7 to the inlet 5 and a temperature sensor 24 located in the return flow

DK 2018 70692 A1 from the heat exchanger before the return flow 8 to the circulation 5.

The control unit associated with the second flow control valve 20 is arranged to adjust, by means of temperature data from these two temperature sensors 23, 24, the second flow control valve 20 on the basis of a difference between the measured temperatures compared to a cooling profile stored in a memory of the control unit associated with the second flow control valve 20. In this way, a suitable cooling of the district heating fluid can be obtained, thereby further saving heat energy.

The sensors 23, 24 also comprise pressure measurement and are provided in the form of PT plugs, the sensor 24 being more specifically arranged for measurement in the valve 20, in particular in an inlet thereof. Thus, the control unit associated with the second flow control valve 20 is also arranged to receive pressure measurement from one or both of the pressure sensors. Thus, the control unit associated with the second flow control valve 20 is arranged to monitor pressure measurement from the pressure sensor 24 located in the return inlet 4a from the heat exchanger, more particularly in an inlet of the valve 20, and is thus arranged to quickly and / or greatly decrease the pressure in the return flow. 4, which will correspond to the system pressure in the district heating system, and to send an alarm to the communication unit in this case. In this way, wiring breaks on the district heating system can be quickly detected.

In one embodiment of the method according to the second aspect of the invention for flow control of the flow control system of FIG. 2, the method comprises the steps of:

providing the flow control system comprising the first flow control valve 12 as shown in FIG. 2 when retrofitting the system to replace the static valve 6 in the system of FIG. 1, that a temperature measurement from the temperature sensor 13 is communicated to the control unit and that the control unit in the box 15 automatically adjusts the flow control valve 12 after the temperature measurement.

The control unit's setting of the flow control valve 12 is based on a user profile stored in the memory of the control unit and which the control unit is supplied from the communication unit.

DK 2018 70692 A1

The control unit's setting of the flow control valve 12 is via a signal sent from the control unit to the actuator 18 of the flow control valve 12 via the connection 19.

In one embodiment of the method according to the third aspect of the invention for retrofitting the flow control system of FIG. 2 in the district heating system of FIG. 1, the method comprises the steps of:

providing an existing district heating system according to FIG. 1, to remove the static valve 6 and to retrofit the flow control system of FIG. 2 comprising the flow control valve 12 as a replacement for the static valve 6.

In addition, the system to the right of valve 12 in FIG. 2, i.e. the system comprising the second flow control valve 20, the actuator 22, the box 21 and the components, including the control unit, herein and the temperature sensors 23, 24, in the manner shown and described for FIG. 2 above in the district heating system of FIG. 1. Hereby the district heating system according to FIG.

2nd

Alternatively, the flow control system shown in FIG. 2 including the flow control valve 12 is installed in connection with the establishment of a new district heating system as shown in FIG. 2, i.e. wherein an existing district heating system as shown in FIG. 1 with a static flow valve 6 to be removed first, i. there is no retrofitting of the flow control system, but merely an installation of the flow control system in the district heating system in fig. 2. Such a new district heating system may, within the scope of the invention, be mounted with or without mounting the system associated with the second flow control valve 20, i. without the second flow control valve 20, the actuator 22, the box 21 and the components, including the control unit, herein and the temperature sensors 23, 24.

The district heating system as shown in FIG. 1, according to the invention, moreover, in general alternative to the embodiment shown in FIG. 2 is designed without the presence of the system associated with the second flow control valve 20, i.e. without the second flow control valve 20, the actuator 22, the box 21 and the components,

DK 2018 70692 A1 including the control unit, herein and the temperature sensors 23, 24. In this case, the district heating system according to this embodiment in the right of the flow control valve 12, the diagram in FIG. 2 is instead designed as the district heating system of FIG. 1 to the right of the static valve 6.

Claims (11)

A district heating system comprising: - a heat exchanger for the transmission of heat energy between a supply side and a user side of the district heating system, - a flow (3, 3a) to and a return flow (4a, 4) on the supply side from the heat exchanger, - an inlet (5) located between the inlet (3, 3a) and the return inlet (4a, 4) from the heat exchanger, and - a flow valve (12) located in the bypass (5), characterized in that the flow valve (12) is a flow control valve (12) which forms part of a flow control system of the district heating system, the flow control system comprising: a first temperature sensor (13, 14) positioned to measure a temperature in the circulation (5), - an electronic control unit and - a battery connected to the control unit for supplying power for operation of the control unit, wherein the control unit can receive measured temperature data from the temperature sensor (13, 14) and can set an opening degree of the flow control valve (12), wherein the control unit comprises means for wireless communication with a communication unit, wherein the controller can receive data from, and thus be remotely controlled from, the communication device and can transmit data for remote logging to the communication device, and wherein the controller is configured as a slave device programmed to periodically request a command from the communication device periodically after a first programmed interval of time. be arranged as a master device, and periodically to transmit data to the communication device periodically after another programmed time interval. A district heating system according to claim 1, wherein the change in the opening degree of the flow control valve is provided by an actuator motor (M) by an actuator. DK 2018 70692 A1 (18), where the actuator motor (M) is powered from the battery. A district heating system according to claim 1 or 2, wherein the means for wireless communication is arranged or programmed to receive data in a time window which is opened with a time interval of 1-120 minutes, 2-60 minutes, 5-30 minutes or 10-20. minutes, e.g. 15 minutes, and / or to send data at a time interval of ¹ Λ -12 hours, 2-10 hours, 3-9 hours, 4-8 hours or 5-7 hours, eg about 6 hours. A district heating system according to any one of the preceding claims, wherein the control unit is arranged for wireless communication with the communication unit via an LPWAN-type network. A district heating system according to any one of the preceding claims, wherein data from the control unit to the communication unit and / or commands from the communication unit to the control unit are supplied via the cloud or a cloud service. A district heating system according to any one of the preceding claims, wherein the actuator (18) remains in substantially the same position when no voltage is applied. A district heating system according to any one of the preceding claims, wherein the stroke length of the flow control valve (12) and / or the actuator (18) is less than 10, 5, 4 or 3 mm, eg 2.5 mm. A district heating system according to any one of the preceding claims, further comprising a second flow control valve (20) mounted in the flow (3, 3a) to or the return flow (4a, 4) from a heat exchanger between a supply side and a discharge side of the district heating system, the second flow control valve (20) is connected to the control unit of the flow control system or another electronic control unit, wherein the control unit of the second flow control valve (20) can set an opening degree of the second flow control valve (20) and comprises means for wireless communication with a communication unit, potentially the same communication unit as for the controller of the flow control system, whereby the controller of the second flow control valve (20) can receive data from and thus be remotely operated from the communication unit. DK 2018 70692 A1 A method for flow control of a flow control system according to any one of the preceding claims, wherein the method comprises the steps of: providing a flow control system according to any of the preceding claims, that a temperature measurement from the temperature sensor (13, 14) is communicated to the control unit and that the control unit automatically adjusts the flow control valve (12) after the temperature measurement. The method of claim 9 for flow control of a flow control system claim 8, wherein the control unit associated with the second flow control valve (20) is arranged to monitor pressure measurement from a pressure sensor (24) located in the return flow (4a, 4) of the heat exchanger and to detect falls. in the return flow pressure (4a, 4), which will correspond to the system pressure in the district heating system, and potentially send data to the communication unit which may trigger an alarm. A method of retrofitting a flow control system in a district heating system, the method comprising the steps of: providing an existing district heating system which comprises - a heat exchanger for the transmission of heat energy between a supply side and a user side of the district heating system, - a flow (3, 3a) to and a return flow (4a, 4) on the supply side from the heat exchanger, - an inlet (5) located between the inlet (3, 3a) and the return inlet (4a, 4) from the heat exchanger, and - a static valve (6) located in the bypass (5), characterized in that the method further comprises the steps: removing the static valve (6) and retrofitting a flow control system to replace the static valve comprising the flow control system - a flow control valve (12) forming part of a flow control system of the district heating system, - a first temperature sensor (13, 14) placed to measure one DK 2018 70692 A1 temperature in circulation (5), an electronic control unit which can receive measured temperature data from the temperature sensor (13, 14) and can set an opening degree of the flow control valve (12), wherein the control unit comprises means for wireless communication with a communication unit, whereby the control unit can receive data from and thus be remotely operated from the communication unit and can send data for remote logging to the communication unit, and wherein the control unit is arranged as a slave unit programmed to periodically request a command from the communication unit, which may be similarly configured as a master unit, periodically after a first programmed time interval. second programmed time interval to send data to the communication device; and - a battery connected to the control unit for supplying power for operation of the control unit, - so that the control unit can set an opening degree of the flow control valve for controlling a flow through the bypass.