DK180868B1 - District heating system and methods for flow control and retrofitting of a flow control system in a district heating system - Google Patents

Abstract

District heating system, comprising a bypass located between the flow and return 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 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 send remote logging data to the communication unit , and wherein the control unit is arranged as a slave unit, which is programmed to periodically after a first programmed time interval to request a command from the communication unit, which may similarly be arranged as a master unit, and to periodically s to send data to the communication device after another programmed time interval. Methods for flow control and retrofitting such a 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 on the supply side from the heat exchanger, a circulation located between the supply and the return from the heat exchanger and a flow valve located in the bypass.

In existing district heating systems, a fluid is heated, usually a liquid, but can also be, for example, steam, typically water, in a central plant or plant, eg a combined heat and power plant. The heated water is distributed via pipe strings in the supply system to the users, who consume the heat via a heat exchanger to supply the user's decentralized, internal circulation, ie. the purchaser system. The detached house system can, for example, for single-family houses be a single system with few internal strings, or can be a central heating system, which can usually be found in larger buildings or multi-storey buildings, and which can comprise a larger number of strings. Often both domestic water and the water that is circulated in the internal heating system are heated, eg for heat supply of radiators in the building.

The distribution in the district heating system takes place in pipe strings, where there is a significant heat loss during the heat transport between the plant and the heat exchanger at the user. The heat loss occurs i.a. as a function of temperature of in particular the flow fluid, i.e. the flow temperature, as a higher temperature leads to higher heat loss. As a rule, the plant is obliged to supply a certain minimum temperature at the supply to the heat exchanger at the user, and in the optimal situation, ie. situation with the least possible heat loss, the flow temperature will be or be slightly above this minimum temperature.

The user's heat exchanger is typically part of a heat interface unit (HIV), which thus establishes the interface between the district heating network and the user's heating system internally. The heat exchanger transfers the heat from the district heating system to the heating system on the user side, ie. the purchaser system. The HIU is usually located on the user side, eg 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 plant, ie. where the string to the user is long, or where the user is near or at the end of a string, a bypass is often located in the district heating system between the supply and the return line

DK 180868 B1 2 from the heat exchanger. The bypass provides a flow path between the inlet and the return inlet, thereby ensuring circulation of the district heating fluid even at the most remote users. Especially in the summer periods, when no heat is used for space heating, but only for domestic hot water, the user's consumption can be so small that the consumption circulation cannot maintain a required minimum temperature of the district heating fluid at the heat exchanger. The bypass can thus be used to ensure a certain minimum temperature, eg 60 ° C, for remote users of the district heating system, even during periods of low consumption. The bypass can be located as part of the HIU and can be located at 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, eg in a well in the road.

A bypass is often retrofitted on the basis of a complaint from the user regarding that the hot water in particular is perceived to have too low a temperature, but a bypass can also be installed in connection with the establishment of the string, especially if it is expected that it may occur. problems with the flow temperature.

A static flow valve can be arranged in the bypass, with which it is possible to manually regulate the flow in the bypass and thus the circulation to ensure a suitable fluid temperature at the user. As a rule, no continuous measurement of the flow temperature of the user is made today, and therefore it can be difficult to ensure an appropriate temperature, especially with the seasonal variations. Since it is cumbersome and expensive to manually set the static flow valve, the valve will often be set so that in the worst case scenario (typically a hot summer day) it can still be expected that the user has a sufficiently high flow temperature. This can mean that the district heating system via the static flow valve is often statically oversized for the flow temperature and, moreover, is not set or regulated as required. The flow temperature at the heat exchanger will therefore often be well above the required minimum temperature, especially during the summer period. During the winter period, the circulation will often not be needed, but the circulation will nevertheless be in operation.

In principle, the static flow valve placed in the circulation together with any other circulation and respective static valves can be adjusted accordingly

DK 180868 B1 3 to a required minimum temperature. However, it can be difficult and cumbersome to provide effective balancing in this way, especially because the valve must be set manually and can be difficult to access, including being located on the user side, and therefore utilities today often have difficulty in both ensuring a required minimum temperature of the flow and to ensure that the temperature is not too high. Often the valve is set only when retrofitting the bypass or when installing a new district heating line and here in such a way that the utility company ensures the minimum temperature regardless of variations in the need, ie. it often results in an oversizing 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 cycles.

Approx. 64% or approx. 1.7 million of the Danish households are supplied with district heating, and there are more than 60,000 km of pipes in the Danish district heating network. Thus, there are already a significant number of the mentioned cycles.

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

CN 104848294 A discloses a district heating system comprising a heat exchanger with a supply side and a consumer side, a supply and a return on the supply side of the heat exchanger, a bypass located between the supply and the return, a flow valve located at the bypass, the flow valve being a three-way temperature control -valve, a control cabinet wired with i.a. the flow valve and a temperature sensor on the consumer side, and a directly connected heating area connected to the return flow for better utilization of excess heat in the return flow.

According to the invention, the above and / or other objects in a first aspect of the invention can be met with a district heating system according to the introduction above, wherein the flow valve is special in that it is a flow control valve which forms part of a flow control system of the district heating system, the flow control system comprises: - a first temperature sensor located to measure a temperature in circulation, - an electronic control unit, and

DK 180868 B1 4 - 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, the control unit comprising means for wireless communication with a communication unit. 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 where the control unit is arranged as a slave unit which is programmed to periodically after a first programmed time interval request a command from the communication unit can be arranged as a master unit, and to periodically send data to the communication unit periodically after another programmed time interval.

The invention thus provides a district heating system with a bypass, where it is possible to regulate the flow control valve automatically and dynamically. This means that it is possible to control the valve and thus the flow through the bypass as needed, ie. so that a temperature in the flow is maintained at or slightly above a required minimum temperature. If the temperature is too low, the control unit will set the valve to a greater degree of opening and thus a greater flow through the bypass, after which the flow temperature will increase. If the temperature is too high, the control unit will conversely set the valve to a smaller degree of opening and thus a smaller flow, after which the flow temperature will fall. The temperature can be measured continuously or periodically after certain time intervals, so that it will be possible to continuously adjust the valve and thus the flow temperature. The control unit can 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 an existing power supply, in particular from the user, which can be cumbersome and also mean that the supply does not has full control over the management of the system,

DK 180868 B1 the power to the system can be short-circuited.

It has thus been realized that with the invention a battery-powered system can be provided which can be remotely controlled and which with suitable control and with current battery technology (eg four lithium AA batteries, ER 14505) can be used for up to five years. or more before replacing the battery. It has also been realized that installation of a system according to the invention can result in savings which, often and for many existing circuits, will have a very short payback time due to large savings on the heat loss on the supply side.

A low energy consumption can be achieved by the control unit being arranged as a slave unit programmed to periodically after a first programmed time interval requesting a command from the communication unit correspondingly arranged as a master unit and to periodically after a second programmed time interval transmitter data to the communication device. Thus, the control unit's means for wireless communication, which would otherwise normally, for example in an WiFi network, will have a relatively high power consumption, be dormant when no data is being sent or received. Energy consumption will therefore be a fraction of the consumption in a system where these means are always active. Thus, it has also been realized that periodic communication with relatively long periods of time in between can be used to advantage in the system according to the invention.

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

In the interval between the request for a command or the transmission of data, the control unit's means for wireless communication can thus be passive or switched off and can thus have an energy consumption close to or close to zero. Thus, the means for wireless communication can be arranged in such a way 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 does not need a connection to an external power supply, eg a circuit at the user, the district heating plant can be ensured full control over the operation of the system.

The district heating system according to the invention enables a dynamic

DK 180868 B1 6 or periodically control the flow in the circulation thus by means of 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 the circuit, for example according to a user profile which the control unit can be supplied with via the communication unit and which can be stored in the control unit. - today. The periodic transmission and reception of data from the control unit means that the energy consumption for operating the means for wireless communication can be kept very low. The control unit can also be arranged to communicate data to the communication unit, which can trigger an alarm after a deviation profile, which can be part of the user profile used. Deviations can in particular be in connection with. relevant measurements of pressure and temperature of sensors located relevant places in the system. Possibly. For example, the communication unit or the cloud (see details below) may be arranged to forward the alarm to another communication unit, for example in the form of an SMS sent to a mobile telephone.

By using such means for wireless communication, such large savings in the energy consumption of the means can be achieved that it is possible to provide a district heating system according to the invention, which in practice can be operated cheaply and efficiently with an ordinary battery or battery system of limited capacity. and which are easy to replace, eg two or four AA batteries. Calculations show that the replacement of four AA batteries, which form the battery for the control unit, can thus be expected to last for at least five years, which is considered to be more than acceptable for the utility company. The batteries can advantageously be replaced in connection with general maintenance.

Thus, with the invention a practically usable district heating system can be obtained, with which the heat loss in connection with circulation in district heating systems is reduced, as the flow through the circulation can be regulated according to requirements from 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 circuit, depending on the circumstances. A smaller flow through the bypass can also lead to less wear of both the pump and pipe systems on the supply side, as the 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

DK 180868 B1 7 change of the degree of opening of the flow control valve and thus the flow through the valve and thus the bypass. The actuator can have a stroke, as a stroke of the flow control valve can be arranged according to the actuator stroke.

The motor of the actuator can advantageously be driven by the same battery as the control unit, as for this purpose a live connection can be provided between the battery and the actuator. Using an actuator and valve with a relatively short stroke, it has been calculated that a battery consisting of four AA batteries can still have the capacity to operate both the actuator and the 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 reception interval for the control unit of 6 hours and a transmission interval of 15 minutes, as these examples of or similar intervals are judged to be suitable for the purpose. The life of the battery depends on the selected user profile, which influences how often the actuator should be activated. In an example of a user profile, the control unit will be programmed so that the actuator only closes the flow control valve in connection with switching between summer and winter and only opens when switching between winter and summer. Even with such a simple user profile, a significant amount of both heat energy and pump energy can be saved. The actuator can alternatively be operated by a separate battery, where the battery in the latter case can be located at, in or can form part of the actuator. This can 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 located with difficulty accessible, eg in a well. On the other hand, the control unit or a box with the control unit can often be located more easily accessible, eg in an installation cabinet at the user's, and it will therefore be easier to replace the battery. The control unit can be arranged for any. periodically to measure the life of the battery, eg by measuring the capacity or voltage, and possibly to send this information to the communication device, whereby it is possible to alert the communication device in good time that replacement of the battery is necessary. The control unit can also be set to set the flow control valve in a predetermined setting, ie. with a predetermined opening area, eg fully open when the battery life is measured to be close to zero, after which flow

DK 180868 B1 8 in the circuit may be present and a required minimum temperature in the circuit may be ensured even when the battery is exhausted.

The flow control system can also be arranged so that the battery supplies power to other parts of the system, including eg the temperature sensor and / or one or more other sensors.

The communication unit can, for example, be a PC, a smart phone or a tablet computer, which can have an Internet connection for connection to the cloud, the control unit being arranged for connection to the cloud, cf. also more about connection to the cloud below. In any case, it is preferred that the control unit can be accessed via an electronic interface (eg web, app or API), where in particular there may be a code at the system, in particular on or at the control unit, where 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. It is also 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 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 system pressure, the first pressure sensor being connected to the control unit so that the control unit can register the system pressure. The system pressure is the system 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 may alternatively be located elsewhere where the pressure represents the system pressure. This makes it possible to identify a line break, which is manifested in particular by a relatively large pressure drop in the system pressure. Often a suitable flow control valve comprises an access to measure the outlet pressure inside the valve itself, for example in the form of a PT port, and the first pressure sensor can advantageously be a PT plug inserted here. The measurement of the temperature via the first temperature sensor can similarly take place here, as the temperature sensor can be part of the PT plug.

Temperature sensors can also be mounted in supply and return from

DK 180868 B1 9 the heat exchanger, and measurement data can be transferred to the control unit, whereby the temperature drop over 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 can be the same sensor as the first temperature sensor, as the temperature in the flow will usually be almost 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 so that the control unit can register the differential pressure and communicate this to the communication unit, after which the pump pressure can be used set the pump pressure to a required minimum level on the supply side. Hereby a further reduction of consumed pump energy and of wear on the pump can be achieved.

One or more or all of the sensors mentioned in the district heating system are preferably digital and passive when not measured, whereby the life of the battery can be further extended.

The control unit can preferably be coded via the communication unit or set with a suitable or adapted user profile, which can be selected automatically or manually according to the circumstances. A profile can, for example, be for seasonal control such as summer / winter operation or can be day-controlled, taking into account, for example, capacity limitations or the like, which can vary over the day.

One or more components of the flow control system and in particular the control unit may be arranged in a control or control box, and there may be one or more outputs from the box to the flow control valve, sensors, battery pack, etc. The battery may alternatively be located inside the box. The box may be provided with a display or screen, where it may be possible to display eg 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 HUI at the user and can be placed in an installation cabinet or the like. The bypass and / or flow control valve may also be located

DK 180868 B1 10 as part of the HUI or can in particular in circulation be located eg 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 sending 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. corresponding means so 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 Li-SOCI2 battery. Calculations show that such a battery can lose less than 1% of its capacity per year over 10 years with one sensor mounted. When controlling using user profiles, the battery life can be reduced, but with the user profiles that are considered relevant, a battery life of more than five years can be expected with a system according to the invention, where 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 can be assembled in a battery pack with a connector which is connected to the control box, or the batteries can be placed inside the control box.

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

The flow control valve can 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, eg a valve as described in applicant WO / 2006/136158 A1, in particular a Frese & Optima® valve,

DK 180868 B1 11 or in WO 2009/135490 A2, in particular a Frese & Optima Compact® valve. The valve can be modified so that it has a smaller stroke. In principle, in an 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, the flow control system can 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 send 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. 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 also be without the feature that the control unit is programmed to periodically request a command from the communication unit after a first programmed time interval. and to periodically send data to the communication device periodically after another programmed time interval. Thus, for example, the control unit may be controlled via a wifi network or via a wired connection.

A district heating system may alternatively be called a district heating installation and is, as the term is used in the present application, a system in which a fluid is heated or cooled in a central plant or plant, eg a combined heat and power plant, and the heated fluid is distributed on the supply side. to several users who consume heat (in the case of heated fluid) or give off heat (in the case of cooled fluid) for heat supply or heat removal of a consumer system at the user. The fluid on the supply side will therefore usually be separated from the fluid on the supply side, as the transfer of the heat energy can take place 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 heat dissipation or the like, it is to be understood that there may be heat reception in the case of a district cooling system.

A heat interface unit (HIU), as the term is used in the present application, establishes the interface with the consumer system at the user and

DK 180868 B1 12 typically comprises a heat exchanger which transfers the heat from the supply side to the collector system.

A bypass in the district heating system, as the term is used in the present application, is located close to or immediately before the heat exchanger between the flow and the return from the heat exchanger or the HIU and thus provides a flow path between the flow and the return.

Such a bypass can be used to ensure a certain minimum flow temperature of eg 60 ° C for remote users of the district heating system.

A flow control valve is, as the term is used in the present application, a valve with which it is possible automatically or non-manually, typically by means of an actuator, to regulate a flow through the valve.

In contrast, a static flow valve is a valve that is set manually, eg by turning a lever.

An actuator, as the term is used in the present application, is a unit which comprises a motor which can set 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 by the valve.

An actuator may be a linear actuator which is preferred in accordance with the present invention and in which the motor can move a valve element of the valve linearly.

Alternative actuators can be used, including actuators where the motor can move a valve element, for example in a circumferential direction.

The stroke of a valve or an actuator is, as the term is used in the present application, the length at which the actuator can move a valve element of the valve between two extreme positions, for example a fully open and a fully closed position.

If the stroke is shorter, less energy must usually be used to move the valve between the two outer positions.

A control unit as the term is used in the present application is an electronic unit which can be used to control or regulate a flow control valve.

The controller may include a memory where one or more user profiles can potentially be stored.

It may also comprise one or more PCBs (printed circuit board) and connections to the individual components of

DK 180868 B1 13 units. The person skilled in the art will know how a suitable control unit can be manufactured for the purpose, and the individual components such as the antenna are available on the market. An opening degree or an opening area / of a valve, as the term is the application time of 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 bypass at a given pump or system pressure. A sensor, as the term is used in the present application, may also be called a sensor, may be electronic and may measure, for example, a pressure or a temperature of a fluid such as the fluid in the circulation on 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 which is often used in connection with flow control valves, in particular 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, as the term is used in 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 comprise several sub-batteries or cells, which may be interconnected. A battery can alternatively be called an element. Any suitable type of battery can be used as the battery of the present invention, including in particular electrochemical batteries such as lithium or Li batteries. A battery may be rechargeable.

A slave unit and a master unit, as the terms are used in the present application, are the components of a system which follows the communication model master / slave known to the person skilled in the art, ie. a model in which a master device, eg the communication unit, has one-way control of one or more slave devices, eg the control unit. The communication unit in the district heating system according to the invention may be for controlling only the control unit in the district heating system according to the invention or may also be for controlling both the control unit and one or more identical, similar or other units.

DK 180868 B1 14 In an embodiment of the district heating system according to the invention, the change of the degree of opening of the flow control valve is provided by an actuator motor in an actuator, where the actuator motor is supplied with power from the battery.

See above for a discussion of potential benefits associated with this. | In one embodiment, the means for wireless communication are 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 with a time interval of 4-12 hours, 2-10 hours, 3-9 hours, 4-8 hours or 5-7 hours, eg about 6 hours.

The time window for receiving data can be, for example, 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 network type LPWAN is also called low-power wide-area network, LPWA network, LPN or low power network and is mainly of the sub-type ultra-narrow band or UNB LPWAN, especially the Sigfox network, which is widespread over large parts of the world. , including Denmark.

LPWAN is a type of wireless telecommunications network that is designed for long-range, low-bit communication between objects or objects such as battery-powered sensors.

LPWAN differs from wireless WAN, which is designed to transfer larger amounts of data between users, consuming 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 supplied via a third party, i.e. neither by the supply nor the user, in particular as or by the Sigfox network.

Other existing UNB LPWAN types include Telensa, Nwave, Weightless and the NbFi protocol.

Other LPWAN types include DASH7, LTE-MEC, MySensors, NB-IoT, RPMA and Taggle Byron.

In connection with the present invention, it has been realized that LPWAN is particularly suitable for use in connection with the control unit's communication with the communication unit, as the low bitrates, the low energy consumption, the periodic communication of data and the master / slave model

DK 180868 B1 15 entails an extremely low energy consumption in connection with the wireless communication, which makes it possible to realize a practically usable, battery-powered district heating system according to the invention.

In one embodiment, data from the control unit to the communication unit and / or commands from the communication unit to the control unit are supplied via a cloud service.

A communication point 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” is hereby inserted. When data is transferred from the control unit, eg via LPWAN, to a data collection in the cloud, the communication unit, eg via the Internet, will be able to send 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. Correspondingly, the control unit can send data to the cloud with the mentioned time interval, and the communication unit can retrieve the data on a possible later appropriate time when the communication unit establishes 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, as the current consumption of the actuator may be or may be close to zero when the actuator is not in operation for setting the flow control valve. This also enables the said design, where the actuator also supplies power from the battery in the system, as a life of the battery of more than five years can thus be achieved.

This can be achieved, for example, by using a three-point actuator, which is an actuator that moves at volts over time, i.e. 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, a 0-10 V modulating actuator, for example, always has a control voltage of eg 4.3 V to determine the 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, eg 2.5 mm.

It has been realized in connection with the invention that such a small

DK 180868 B1 16 stroke of the valve / actuator can be used, as precise setting of the flow control system will usually not be a requirement for normal operation of the system. The smaller stroke can thus mean that the actuator's motor consumes less power when setting the valve, which in turn can extend the life of the battery, in the case where the actuator is supplied with power from the battery.

In one embodiment, the district heating system further comprises a second flow control valve mounted in the supply to or return from a heat exchanger between a supply side and a customer side of the district heating system, the second flow control valve being connected to the control unit of the flow control system or another electronic control unit. can set 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 for the control unit of the flow control system, whereby the control unit for the second flow control valve can receive data from and thus be remotely controlled from the communication unit .

Thus, it may be possible via the communication unit wirelessly and remotely to turn off the heat of a user, eg in connection with non-payment. Today, it is often the case that the plant must have access to the property at the user to shut off the heat, which can be associated with inconvenience and high costs, including especially in cases where it is necessary to involve the authorities.

The second flow control valve and the 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 comprise one or more of the options of the first flow control system mentioned above, just as one or more of the components herein may be used in both flow control systems.

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

The second flow control valve and the associated control unit can

DK 180868 B1 17 each be according to any of the embodiments mentioned for the first flow control valve and its associated control unit. Below, the second flow control valve may, for example, 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 flow to the heat exchanger and / or a temperature sensor located in the return flow from the heat exchanger. The control unit connected to the second flow control valve can, by means of temperature data from these two temperature sensors, be arranged to set the second flow control valve on the basis of a difference between the measured temperatures, if any. compared with a cooling profile stored in a memory of the control unit connected to the second flow control valve. In this way, a suitable cooling of the district heating fluid can be achieved, whereby further heat energy can be saved.

One or both sensors may also comprise pressure measurement and may be PT plugs, and the control unit associated with the other 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 further be arranged to detect rapid and / or large drops in the pressure in the return flow which will correspond to the system pressure in the district heating system. potentially send an alarm to the communication device. In this way, cable breaks on the system can be detected quickly.

Alternatively or additionally, the system 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 embodied as part of a district heating system according to the invention. but designed without the flow control system.

Another aspect of the invention involves a method of flow control of a flow control system as defined in any one of claims 1 to 8, wherein the method comprises the steps of: providing a flow control system as defined in any one of said invention. of claims 1 to 8, that a temperature measurement from the temperature sensor is communicated to the control unit, and that the control unit automatically sets the flow control valve after the temperature measurement.

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

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

| an embodiment of this method for flow control of the district heating system according to the above embodiment, wherein a second flow control valve is mounted in the supply to or return from a heat exchanger between a supply side and a take-off side of the district heating system, the other flow control valve being connected to the control unit the flow control system or another electronic 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 unit, potentially the same communication unit as for the control unit of the flow control system. the control unit for the second flow control valve can receive data from and thus be remotely controlled from the communication unit, the method comprises that the control unit connected to the second flow control valve is arranged to monitor pressure measurement from a pressure ensor located in the return line from the heat exchanger and to detect a drop in the pressure in the return line, which will correspond to the system pressure in the district heating system, and potentially send data to the communication unit that can trigger an alarm.

| a third aspect, the invention involves a method of

Mounting a flow control system in a district heating system, the method comprising the steps of: providing an existing 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 on the supply side of the heat exchanger, - a bypass located between the flow and the return from the heat exchanger and - a static valve located in the bypass, the method being special by further comprising the steps of: disassembling the static valve and retrofitting a flow control system as a replacement for the static valve, where the flow control system comprises - a flow control valve which forms part of a flow control system of the district heating system, - a first temperature sensor, which is placed 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, 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 controlled from the communication unit and can send data for remote logging to the communication unit, and where the control unit is arranged as a slave unit programmed to interrogate a command from the communication unit, which may similarly be arranged as a master unit, periodically after a first programmed time interval, and to send data to the communication unit periodically after a second programmed time interval, and - a battery connected to the control unit for supplying power for operation of the control unit,

DK 180868 B1 20 - 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 may 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 in the following 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 which has been modified for an embodiment of the district heating system according to the present invention.

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

The district heating system in fig. 1 comprises a heat exchanger (not shown) arranged HUI 2 for transmission of 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, a supply 3 to and a return 4 on the supply side from HIU 2, a bypass 5 located between the supply 3 and the return 4 from HIU 2 and a flow valve 6 located in the bypass 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 the supply system to the end string shown, which removes the heat via the heat exchanger in HIU 2 to supply of the user's decentralized, internal circulation, ie. the purchaser system, which is located to the right of the HIU in the figure.

The heat exchanger is part of HIU 2, which thus establishes the interface between the district heating network and the heating system internally at the user. The heat exchanger transfers the heat from the district heating system to the heating system on the user side, ie. the purchaser system. The HIU is located on the user side, eg in an installation cabinet in an installation room in the user building.

The bypass 5 provides a flow path between the inlet 3 and the return inlet 4, thereby ensuring circulation of the district heating water near HIU 2. The bypass is used to ensure a minimum temperature of eg 60 ° C the user, even during periods of low consumption. The circuit is not located here as part of the HIU,

DK 180868 B1 21 but outside the user side, eg in a well in the road.

As mentioned, a static flow valve 6 is arranged in the circulation, with which it is possible to manually regulate the flow in the circulation and thus the circulation to ensure a suitable fluid temperature at the user. No continuous measurement of the flow temperature of the user is made, and the valve is set so that in the worst case (typically a hot summer day) it can still be expected that there is a sufficiently high flow temperature of the user.

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

The district heating system in fig. 1 further comprises a second static valve 9 in the outlet 3, more specifically in the part 3a between the supply 7 to the bypass 5 and the HIU 2 and a third static valve 10 in the return 4, more specifically in the part 4a between the HIU 2 and the return 8 from the bypass 5. Herewith it is possible to manually set or close the flow in the flow 3a and the return flow 4a from the heat exchanger in HIU 2, respectively.

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

In FIG. 2, the static valve 6 in FIG. 1 replaced with a flow control system 11 to provide a district heating system according to the invention. The flow control system 11 is thus mounted in an embodiment of the method according to the third aspect of the invention, the static valve 6 in fig. 1 has first been dismantled 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 temperature and pressure in the flow 7 to and the return flow 8 from the flow 5, respectively.

The flow control system 11 further comprises a control box 15, in which an electronic control unit (not shown) and an internal battery (not shown) are provided with 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, 16, 17 respectively, and can set an open

DK 180868 B1 22 degree of flow of the flow control valve and thus the flow of district heating water through the valve 12, as the actual flow also depends on a differential pressure across the valve.

The control unit comprises means (not shown) for wireless communication with a communication unit (not shown), 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.

The control unit is arranged as a slave unit, which is programmed to periodically after a first programmed time interval to request a command from the communication unit, which may similarly be arranged as a master unit, and to periodically after a second programmed time interval to send data for communication. - the device.

It is thus possible via 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 bypass as required, ie. so that a temperature in the five course is kept at or slightly above the required minimum temperature.

If the temperature is too low, the control unit will set the valve to a greater degree of opening and thus a greater flow through the bypass, after which the flow temperature will increase.

If the temperature is too high, the control unit will conversely set the valve to a smaller degree of opening and thus a smaller flow, after which the flow temperature will fall.

The temperature can be measured continuously or periodically after certain time intervals, so that it will be possible to continuously adjust the valve and thus the flow temperature.

The control unit is designed to dynamically regulate the flow through the circuit 5 as a function of the temperature measured in the circuit 5. The battery comprises a battery pack with four Lithium AA batteries, 3.6V ER 145050. In the interval between the request for a command or the transmission of data, the control unit's means for wireless communication are passive or switched off and thus have an energy consumption close to or zero.

The means for wireless communication are also arranged in such a way 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.

GB 180868 B1 23 As the control unit is not connected to an external power supply, the district heating plant is guaranteed full control over the operation of the system.

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 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 also arranged to communicate data to the communication unit, which can trigger an alarm after a deviation profile which is part of the user profile used. The deviations are more specifically deviations in relation to defined pressures 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 an appropriate change in the degree of opening 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.

The motor M of the actuator is driven by the same battery as the control unit, a live connection 19 being provided for this purpose between the battery and the actuator 18. The connection 19 also comprises lines for controlling the motor by means of the control unit.

The control unit is set to a reception interval of 6 hours and a transmission interval of 15 minutes.

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

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

The communication unit is a smart phone which has an Internet connection for connection to the cloud, as the control unit is arranged for connection with the cloud, cf. also more about connection with the cloud below. The communication device can be accessed via a mobile app and there is a code on the box

DK 180868 B1 24 15, where supplying the communication unit with the code can identify the system and / or in case of retrofitting the system can suggest a mounting location for the system. An alarm limit value can also be encoded via the app 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 has been 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 register the system pressure.

In other embodiments, temperature sensors can also be mounted in supply 3 and return 4 from the heat exchanger in HIU 2, and measurement data can be transferred to the control unit, whereby the temperature drop over the heat exchanger can be monitored and the system can be set to achieve an optimal or improved (typically higher ) temperature drop across 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 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 register the differential pressure and communicate this to the communication unit, after which the pump pressure can be used set the pump pressure to a required minimum level on the supply side.

The control unit can be coded or set via the communication unit with a suitable or adapted user profile, which can be selected automatically or manually according to the circumstances. A profile can, for example, be for seasonal control such as summer / winter operation or can be day-controlled, taking into account, for example, capacity limitations or the like, which can 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, eg for selecting a user profile.

The individual batteries in the battery are collected in a battery pack in box 15.

The flow control valve 12 is of the type PICV (pressure independent

DK 180868 B1 25 control valve), in particular in applicant's WO 2009/135490 A2, in particular a Frese & Optima Compact® valve. The valve is modified so that it has 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 the communication with the communication unit and enable electronic, wireless communication with the communication unit. The time window for receiving data for the control unit is 10 seconds. The control unit is also arranged for wireless communication with the communication unit via an LPWAN-type network, in particular the Sigfox network. Data from the control unit is supplied to the communication unit and / or 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 data collection in the cloud, the communication unit can send command to the cloud via the Internet 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. Correspondingly, the control unit can send data to the cloud with the mentioned time interval, and the communication unit can retrieve the data at a possible later appropriate time when the communication device establishes 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.

In that embodiment, the district heating system comprises in fig. 2 further another flow control valve 20 mounted in the return flow 4 from the heat exchanger. The second flow control valve 20 is connected to a second electronic control unit. The control unit sets an opening degree of the second flow control valve 20 and comprises corresponding means for wireless communication with the communication unit, whereby the control unit can correspondingly receive

DK 180868 B1 26 data from and thus be remotely controlled from the communication unit.

This makes it possible to switch off the heat of a user wirelessly and remotely via the communication unit, eg 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. Correspondingly, 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 part 4a and the static valve 10.

The control unit connected to the second flow control valve 20 is connected to a temperature sensor 23 located in the flow 3 of the heat exchanger after the flow 7 to the bypass 5 and a temperature sensor 24 located in the return flow 3 from the heat exchanger before the return flow 8 to the flow 5.

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

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. The control unit associated with the second flow control valve 20 is thus also arranged to receive pressure measurement from one or both of the pressure sensors. The control unit associated with the second flow control valve 20 is thus arranged to monitor pressure measurement from the pressure sensor 24 located in the return lab 4a from the heat exchanger, more specifically in an inlet of the valve 20, and is thus arranged to detect rapid and / or large drop in return pressure. barrel 4, which will correspond to the system pressure in the district heating system, and to send an alarm to the communication unit in that case. Hereby, wire breakage on

DK 180868 B1 27 district heating system could be detected quickly.

| an embodiment of the method according to the second aspect of the invention for flow control of the flow control system in 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 by retrofitting the system to replace the static valve 6 in the system in 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 sets 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 which is stored in the memory of the control unit and which the control unit is supplied with from the communication unit.

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

| an embodiment of the method according to the third aspect of the invention for retrofitting the flow control system in fig. 2 in the district heating system in 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 according to fig. 2 comprising the flow control valve 12 as a replacement for the static valve 6.

In addition, the system to the right of the 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, therein as well as the temperature sensors 23, 24, in the manner shown and described for fig. 2 above in the district heating system according to FIG. 1. Hereby the district heating system according to fig.

2.

Alternatively, the flow control system shown in FIG. 2 comprising 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. where an existing one is not first provided

DK 180868 B1 28 district heating system as shown in fig. 1 with a static flow valve 6, which must first be removed, ie. there is no retrofitting of the flow control system, but only a mounting of the flow control system in the district heating system in fig. Such a new district heating system can within the scope of the invention be mounted with or without mounting of the system connected to the second flow control valve 20, i.e. without the second flow control valve 20, the actuator 22, the box 21 and the components, including the control unit, therein as well as the temperature sensors 23, 24.

The district heating system as shown in fig. 1 could according to the invention moreover generally be an alternative to the embodiment shown in fig. 2 is designed without the presence of the system connected to the second flow control valve 20, ie. without the second flow control valve 20, the actuator 22, the box 21 and the components, including the control unit, therein and the temperature sensors 23, 24. | In this case, the district heating system according to this embodiment in the diagram to the right of the flow control valve 12 in FIG. 2 can instead be designed as the district heating system in fig. 1 to the right of the static valve 6.

Claims (11)

DK 180868 B1 29 PATENTKRAV 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 supply (3, 3a) to and a return (4a, 4) on the supply side from the heat exchanger, - a bypass (5 ) located between the supply (3, 3a) and the return (4a, 4) from the heat exchanger and - a flow valve (12) located in the bypass (5), the flow valve (12) being a flow control valve (12) forming part of a flow control system of the district heating system, the flow control system comprising: - a first temperature sensor (13, 14) located to measure a temperature in the circulation (5), and - an electronic control unit, where 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), characterized in that - the flow control system further comprises a battery connected to the control unit for supplying power for operation of the control unit, wherein the control unit one 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 send data for remote logging to the communication unit, and wherein the control unit is arranged as a slave unit programmed for periodically after a first programmed time interval to request a command from the communication unit, which may similarly be arranged as a master unit, and to periodically send data to the communication unit periodically after another programmed time interval. A district heating system according to claim 1, wherein the change of the degree of opening of the flow control valve is provided by an actuator motor (M) of an actuator DK 180868 B1 30 (18), where the actuator motor (M) is supplied with power from the battery. A district heating system according to claim 2, wherein the actuator (18) remains in the same position when no voltage is applied. District heating system according to claim 2 or 3, 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, wherein the means for wireless communication are 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, eg approx. 15 minutes, and / or to send data with a time interval of 4-12 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 provided via the cloud or a cloud service. A district heating system according to any one of the preceding claims, further comprising a second flow control valve (20) mounted in the supply (3, 3a) to or the return (4a, 4) from a heat exchanger between a supply side and a customer side of the district heating system, wherein 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 control unit of the flow control system, whereby the control unit for the second flow control valve (20) can receive data from and thus be remotely controlled from the communication unit. A method of flow control of a flow control system as defined in any one of the preceding claims, wherein the method DK 180868 B1 31 comprises the steps of: providing a flow control system as defined in any one 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 sets the flow control valve (12) after the temperature measurement. The method of claim 9 for flow control of a flow control system according to 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 (4a, 4) of the heat exchanger and to detect a drop in the pressure in the return line (4a, 4), which will correspond to the system pressure in the district heating system, and potentially send data to the communication unit, which can 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 comprising - a heat exchanger for transmitting heat energy between a supply side and a user side of the district heating system, - cet flow (3, 3a) to and a return (4a, 4) on the supply side from the heat exchanger, - a bypass (5) located between the flow (3, 3a) and the return (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 of: removing the static valve (6) and retrofitting a flow control system as a replacement for the static valve, the flow control system comprising - a flow control valve (12) forming part of a flow control - ring system of the district heating system, - a first temperature sensor (13, 14), which is placed to measure a temperature in the circulation (5), - an electronic control unit which can receive age measured temperature DK 180868 B1 32 turn data from the temperature sensor (13, 14) and can set an opening degree of the flow control valve (12), 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 remote logging data to the communication unit, and wherein the control unit is arranged as a slave unit, which is programmed to periodically after a first programmed time interval to request a command from the communication unit, which can be similarly arranged as a master unit, and to periodically after another programmed time interval send data to the communication unit, 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 orbit.