Method for operating and / or monitoring a water circulation

Abstract

The invention relates to a method for operating a water circulation system in a drinking water supply network (30), which comprises at least one circuit (31) for circulating drinking water, a centrifugal pump unit (2) for receiving drinking water from and supplying it to the circuit (31), and at least one consumer (32) supplied with drinking water from the circuit (31). The centrifugal pump unit (2) comprises a pump unit (2a), an electric motor (2b) driving the pump unit, and pump electronics (2c) for controlling and regulating the electric motor (2b). The pump unit acquires operating information about the water circulation or the drinking water supply network (30), which it uses to control the water circulation. The centrifugal pump unit (2) actuates a flushing valve (7a) connected to the circuit (31) for draining drinking water from the circuit (31) by opening, closing, or blocking the flushing valve (7a).

Description

[0001] The invention relates to a method for operating a water circulation in a drinking water supply network, which has at least one circuit formed by a circulation line for circulating drinking water, a centrifugal pump unit for receiving drinking water from and pumping it into the circuit, and at least one consumer supplied with drinking water from the circuit, wherein the centrifugal pump unit comprises a pump unit, an electric motor driving this pump unit, and pump electronics for controlling and regulating the electric motor.

[0002] Drinking water supply networks in buildings provide consumers with cold or hot drinking water via taps, toilets, or showers. To ensure the hygienic safety of drinking water, the proliferation of germs in the drinking water must be prevented. Depending on the type of consumer, the frequency of use of the premises, and the building's location, water is drawn more or less regularly, sometimes even infrequently. Irregular water draw-off results in stagnant water in the supply lines to the consumers, which in turn promotes contamination with bacteria and viruses. This is a particular problem in large drinking water networks such as those found in hospitals, hotels, and public buildings.To improve drinking water quality, drinking water supply networks with circuits are being implemented in which the drinking water is pumped to the extraction points in the circuit.

[0003] In addition to structural requirements to prevent stagnation and material specifications, there are operational requirements regarding drinking water temperature and water exchange. For example, the VDI DVGW 6023 guideline "Hygiene in Drinking Water Installations" stipulates that a complete exchange of the circulating drinking water must take place every 72 hours to replace unused drinking water in the circulation line with fresh, cold drinking water. This water exchange is achieved by draining the water from the circulation line into a drain and no longer using it as drinking water.

[0004] According to the VDI DVGW 6023 guideline "Hygiene in drinking water installations", the drinking water temperature for cold drinking water must be as cold as possible and a maximum of 25°C to prevent an impermissible increase in germs.

[0005] There are also temperature requirements for hot drinking water to prevent an impermissible increase in germs, but these are minimum temperatures, as described in the DVGW W511 worksheet.

[0006] In both cases, i.e., for "cold drinking water" and "hot drinking water," a system designed with a circulation system is helpful. Localized heat inputs or losses then do not directly lead to unacceptable temperatures, but are distributed throughout the entire circulated water volume, changing the water temperature only slightly. This prevents unacceptable temperature ranges and the proliferation of germs in the drinking water.

[0007] The demand for drinking water circulation, especially in cold water networks, while maintaining hygiene standards is met on the market by arranging individually assembled and connected components such as centrifugal pumps, valves, pipe sections, sensors, flushing units, cooling units, filters, etc. In addition, ready-made compact units are also known that combine at least some of the aforementioned individual components into a single unit, so that it only needs to be installed and connected in the building. A unit of this type typically has a higher-level control electronics unit, possibly located externally to the unit, to which the sensor and actuator components of the unit are connected.

[0008] Against this background, the object of the present invention is to provide a method for operating a water circulation system in a drinking water supply network that ensures compliance with hygiene standards in the water circulation system, can be set up with minimal assembly and cabling effort, and in particular takes advantage of synergies between the individual components of the drinking water circulation system.

[0009] This problem is solved by a method with the features of claim 1. Advantageous further developments are specified in the dependent claims and are discussed below.

[0010] According to the invention, a method for operating a water circulation in a drinking water supply network is proposed, which has at least one circuit formed by a circulation line for circulating drinking water, a centrifugal pump unit for taking in drinking water from and pumping it into the circuit and at least one consumer fed with drinking water from the circuit, wherein the centrifugal pump unit has a pump unit, an electric motor driving the same and pump electronics for controlling and regulating the electric motor and determines operating information about the water circulation or the drinking water supply network and uses it to control and / or monitor the water circulation, wherein the centrifugal pump unit controls a flush valve connected to the circuit for draining drinking water from the circuit by opening, closing or inhibiting the flush valve, as explained below.

[0011] The core of the invention is therefore to utilize an existing system component, namely the centrifugal pump unit and its pump electronics, in particular their intelligence and functionality, for maintaining and monitoring compliance with hygiene standards in drinking water supply. A higher-level central control electronics unit is thus unnecessary. Consequently, the effort required for the installation and wiring of the necessary sensors and / or actuators is also reduced, since the centrifugal pump unit itself functions as a sensor and / or actuator, and the pump electronics as the control unit for water circulation.

[0012] The method according to the invention can be used for both hot water and cold water circulation systems.

[0013] The centrifugal pump unit is primarily operated in circulation mode, particularly continuously, where it pumps the drinking water through the circuit. The centrifugal pump unit is therefore located within the circuit. This ensures protection against excess temperatures and stationary temperature conditions in the drinking water supply network, which can be easily evaluated. The centrifugal pump unit can be operated at a constant speed, with flow rate control, or with pressure control. Controlling the centrifugal pump unit to a constant flow rate is useful, for example, if manual branch balancing valves or flow dividers are installed in the drinking water supply network. Proportional pressure control, on the other hand, is suitable if control valves are installed in the drinking water supply network. During circulation mode, the centrifugal pump unit monitors the water circulation.

[0014] For example, the centrifugal pump unit can determine its flow rate, delivery head, differential pressure, or the temperature of the pumped water and monitor for changes or when a limit value is reached. This eliminates the need for separate sensors or sensor components such as flow sensors, pressure sensors, or temperature sensors, which would otherwise require installation and data cabling within the drinking water supply network. Furthermore, the centrifugal pump unit can assess the current operating status, including the hygienic condition of the water circulation system and the drinking water network, and, if necessary, take appropriate measures to maintain drinking water hygiene. Finally, it can also detect short-term and long-term changes in the operating status.

[0015] The flow rate, the discharge head / differential pressure or the temperature can each be determined using a sensor integrated into the centrifugal pump unit (volume flow sensor, differential pressure sensor, temperature sensor) or mathematically from pump variables, as is known in the state of the art.

[0016] The flow rate measured by the centrifugal pump unit tells the system the amount of water circulating in the circulation line per unit of time. Furthermore, the pump head measurement tells the system whether and to what extent a pressure drop occurs along the circulation line, i.e., whether one or more taps are open. Finally, by measuring the temperature of the water flowing through it, the centrifugal pump unit can assess the temperature-related hygiene status of the drinking water supply network.

[0017] In one design variant, the centrifugal pump unit can be positioned upstream of a flushing valve connected to the circuit for draining water from the circuit. This has the advantage that the drinking water flowing from the circuit, which is to be separated via the flushing valve, flows through the centrifugal pump and can therefore be monitored or measured by the centrifugal pump in various ways, for example with regard to temperature, flushing volume, flow velocity, etc.

[0018] Flushing operation, alongside circulation, represents another operating mode of the drinking water supply network and the pump unit. During flushing operation, the pump unit is preferably switched off, as the water flows automatically to the flushing valve due to atmospheric pressure.

[0019] In the aforementioned arrangement, it can be provided that the centrifugal pump unit, in the drive-free state, determines whether its speed is greater than zero in order to detect flushing activity or to check the flushing valve. The centrifugal pump unit, in particular the pump electronics, can thus assume that the flushing valve is open if the speed is greater than zero. This is because when the flushing valve is open, the water flows through the centrifugal pump unit to the flushing valve and out of the circuit, thereby driving the impeller of the pump unit like a turbine, even though the electric motor is not driven. Alternatively, the centrifugal pump unit, in particular the pump electronics, can assume that the flushing valve is defective if the speed is zero during a triggered flushing operation. This is because when the flushing operation has been triggered, i.e.If the flush valve was triggered to open, the water should flow through the centrifugal pump unit to the flush valve, thereby driving the impeller. If this is not the case, the flush valve has obviously remained closed despite being triggered and is therefore defective.

[0020] In another design variant, the centrifugal pump unit can be positioned downstream of a flushing valve connected to the circuit for draining water from the system. This has the advantage that the potable water to be separated via the flushing valve does not flow through the centrifugal pump, and thus the centrifugal pump is not over-flowed when the flushing valve is open. This means the impeller of the centrifugal pump is not driven by the drained water flowing back into the circuit, and the electric motor does not operate as a generator. This requires special measures to prevent overloading the frequency converter of the pump electronics. In such an arrangement, the centrifugal pump unit is also de-energized during flushing operation. Furthermore, the centrifugal pump unit can be configured to determine whether its rotational speed is greater than zero in the de-energized state, in order to check a non-return valve.The backflow preventer prevents fresh drinking water from flowing against the intended circulation direction when the flushing valve is open and being separated via the flushing valve. This prevents the centrifugal pump unit, and in particular the pump electronics, from assuming during flushing that a backflow preventer connected in series with the centrifugal pump unit, especially one located between the flushing valve and the centrifugal pump unit, is defective if the rotational speed is greater than zero.

[0021] Determining the rotational speed is possible using a known method according to the state of the art. For example, this can be done via the electrical voltage induced in the stator by a permanent magnet rotor, i.e., the so-called "back EMF". Alternatively, rotation of the impeller can be detected using a Hall sensor, which detects the magnetic field of the rotor magnets or other magnets on a rotating component of the pump unit, for example, on or in the impeller, where a change in the magnetic field indicates rotation of the rotor.

[0022] The unpowered state is a state in which the electric motor is unpowered, i.e., no electrical torque acts on the rotor. In other words, the electric motor is switched off.

[0023] Additionally or alternatively, the centrifugal pump unit can be configured to perform a short-term assessment of the drinking water supply network's condition. This allows the pump unit to continuously or quasi-continuously determine its operating point and monitor changes in this point, enabling the detection of short-term fluctuations. This means that each determined operating point is stored and compared with the last determined operating point or with several past operating points. Quasi-continuous determination occurs when the operating point is determined in discrete time steps, for example, in intervals ranging from one millisecond to a few seconds or tens of seconds. For instance, the pump unit, or rather its electronics, can be configured to assume a draw-off activity at the consumer when the operating point changes.A draw-off activity occurs when water is drawn from the circulation line at at least one consumer. Fresh drinking water then flows into the circulation line, provided, for example, by a water supplier at a house connection.

[0024] When water withdrawal is stopped, the operating point returns to the initial state it was in before the water withdrawal. This allows the centrifugal pump unit to determine the duration of a water withdrawal by measuring the time elapsed from the change in the operating point until the return to the initial state. If two or more consumers are opened consecutively, this results in multiple, sudden changes in the operating point in the same direction. This allows the centrifugal pump unit to determine how many consumers are simultaneously withdrawing water based on the changes in the operating point.

[0025] Determining the frequency of water withdrawals within a specific period, the duration of individual or total withdrawals, and / or the withdrawal intensity (i.e., the number of simultaneously open taps) has the advantage that the centrifugal pump unit, or rather its electronics, can assess the amount of water exchanged in the circulation line. With this information, the centrifugal pump unit can, for example, suppress flushing if the frequency, duration, and / or intensity of water withdrawals within a period is sufficiently high to maintain drinking water hygiene. This has the advantage of preventing unnecessary flushing and thus saving water. Sufficiently high water withdrawal or sufficient withdrawal activity is present at least when the entire water volume of the circulation line is used within 72 hours.at least the entire volume of the circulation line has been replaced with fresh drinking water.

[0026] However, simply considering the total volume of water exchanged over a period of time does not guarantee that all of the old water in the circulation line has actually been replaced with fresh water. This is because freshly flowed water may have been withdrawn instead of the old water during one or more water withdrawals. This means that even if a water volume equivalent to the contents of the circulation line is replaced, a residual portion of old water may still remain in the circulation line. For this reason, it is advantageous to suppress flushing only when at least 1.5 or 2 times the water volume of the entire circulation line has been withdrawn within 72 hours.

[0027] In another embodiment of the process, the centrifugal pump unit, or rather its electronics, can additionally or alternatively control a flushing valve connected to the circuit to drain water from the system. This allows the centrifugal pump unit not only to monitor water circulation and the drinking water network, but also to initiate measures to ensure drinking water hygiene. This can be done in various ways, both with regard to triggering and terminating a flushing cycle. To save energy, the centrifugal pump unit can switch off its electric motor after the flushing valve has been activated.

[0028] For example, the centrifugal pump unit, or rather its electronics, can trigger the flushing valve if no or insufficient water usage is detected at the point of use over a certain period. This can be described as stagnation flushing. In this case, no or not enough water has been drawn from the circulation line and replaced with fresh drinking water within that period, and germs can multiply in the stagnant, still circulating drinking water. The centrifugal pump unit then determines its operating point during circulation and monitors it for changes. If there is no change or an insufficient frequency of changes, the flushing valve can be triggered. The period can be, for example, 72 hours. However, if sufficient water usage is detected, the flushing valve can be omitted, thus minimizing the amount of water that needs to be removed.

[0029] Alternatively, the centrifugal pump unit, or rather its electronics, can trigger the flushing valve, particularly regularly after a certain period of time, for example, every 72 hours. This can also be referred to as stagnation flushing. During circulation, the centrifugal pump unit then determines the time elapsed since the last flush and compares it to the specified period. This ensures that, regardless of any specific condition, the water in the entire circulation line is replaced with fresh drinking water after the specified period has elapsed.

[0030] According to a further alternative, the centrifugal pump unit, or rather the pump electronics, can trigger the flush valve when the temperature of the pumped water reaches or exceeds an upper limit. This can be referred to as temperature flushing. The centrifugal pump unit then determines the temperature during circulation and compares it with the upper limit. For example, the upper limit is 25°C. When the flush valve is triggered, the water heated in the circulation line flows to the flush valve and is separated there. Fresh, cooler drinking water then generally flows into the circulation line, for example, with a maximum temperature of 16°C. This ensures that the water in the circulation line does not heat up to a temperature that promotes germ formation.

[0031] In the event that the fresh drinking water already exceeds the limit, which may be the case at high ambient temperatures, e.g., in summer, the aforementioned temperature condition would always be met and the flush valve would remain permanently open. To avoid this, the temperature condition can be suppressed and flushing can be performed regularly after a certain period of time, for example, every 24 hours.

[0032] The aforementioned limit value can be a maximum temperature, at which point the centrifugal pump unit immediately triggers a temperature flush. Alternatively, the centrifugal pump unit, or rather its electronics, can trigger a temperature flush at a lower temperature if this temperature is exceeded for a certain period. The flush valve is therefore activated when the temperature of the pumped water remains above a specific limit value for a predetermined period. This limit value could be, for example, 23°C and the period 3 minutes. In this case, the centrifugal pump unit monitors during circulation whether two conditions are met simultaneously: whether the temperature limit value is exceeded and whether this is the case for the specified duration.The latter can be recorded by a counter that is triggered by reaching or exceeding the temperature limit. If the temperature of the pumped water falls below the limit again, the counter can be reset.

[0033] According to a further alternative, the centrifugal pump unit, or rather the pump electronics, can trigger the flush valve when a specific date and / or time is reached. In this case, the centrifugal pump unit, or rather the pump electronics, has an internal clock with a date, so that it can be checked during circulation whether the specific date and / or time has been reached.

[0034] According to another alternative, the centrifugal pump unit, or rather the pump electronics, can trigger the flushing valve when it receives a manual flushing command via a display and control unit of the centrifugal pump unit. This allows flushing to be initiated manually on site.

[0035] According to a further alternative, the centrifugal pump unit, or rather the pump electronics, can trigger the flushing valve when it receives a remote trigger command for flushing via a communication interface, in particular a web interface, which is part of the pump electronics. This also enables manual triggering of a flush, which can take place at any time. The initiator can be located near the centrifugal pump unit and send the remote trigger command to the centrifugal pump unit, for example, via a mobile device such as a smartphone or a tablet. The communication interface in this case is preferably radio-based, and the external device is connected to the centrifugal pump unit wirelessly, e.g. via Bluetooth, NFC, ZigBee, WLAN, etc. Alternatively, the remote trigger command can come via a communication network to which the centrifugal pump unit is connected via the communication interface, such asan Ethernet (LAN or WLAN), the Internet, a Modbus, BacNet or the like.

[0036] Although the aforementioned conditions that trigger flushing are each alternatives, two or more of them can also be active and monitored simultaneously in order to monitor drinking water hygiene in several respects.

[0037] As mentioned previously, the termination of a rinsing process can also be done in different ways.

[0038] For example, the centrifugal pump unit, or rather the pump electronics, can close the flush valve when the temperature of the pumped water reaches or falls below a lower limit. The centrifugal pump unit then determines the temperature during flushing and compares it with the lower limit. As soon as the fresh drinking water flowing into the circulation line reaches the centrifugal pump unit, the measured temperature corresponds to the temperature of the fresh drinking water, which is usually significantly lower than the aforementioned upper limit. For example, the lower limit is 20°C.

[0039] Alternatively, the centrifugal pump unit or the pump electronics can close the flush valve when the temperature no longer changes or the change in the temperature of the pumped water reaches or falls below a limit value. The centrifugal pump unit then determines the temperature gradient during flushing and evaluates it. When the fresh drinking water reaches the centrifugal pump unit, the determined temperature drops to the temperature of the fresh drinking water, which is a minimum and remains constant. If the temperature no longer changes, i.e. the temperature gradient is zero, or only changes slightly, i.e. the temperature gradient is below the limit value e.g. 0.1 K / 60s, the centrifugal pump unit can assume that the circulation line has been completely flushed and end the flushing.Compared to using a lower temperature limit, this has the advantage that the flushing is not terminated too early and the termination depends on the temperature at which the supplier delivers the drinking water.

[0040] According to another alternative, the centrifugal pump unit, or rather its electronics, can close the flushing valve when a predefined flushing duration has elapsed. In this case, the centrifugal pump unit determines the time elapsed since the flushing valve was activated and compares it to the predefined flushing duration. This flushing duration corresponds to at least the time required to exchange the entire volume of water in the circulation line. It can be preset for the centrifugal pump unit, for example, via the display and control unit or the communication interface. However, the centrifugal pump unit can also determine the flushing duration itself by opening the flushing valve and measuring the time until the temperature no longer changes or until the temperature of the pumped water reaches or falls below a certain threshold. This can be done, for example, once during the initial commissioning of the centrifugal pump unit.

[0041] According to another alternative, the centrifugal pump unit, or rather its electronics, can close the flushing valve once a predefined flushing volume has been discharged. During flushing, the centrifugal pump unit then determines the amount of water discharged based on its flow rate and compares it to the predefined flushing volume. This flushing volume corresponds to at least the volume of water in the circulation line or the drinking water network. It can be specified to the centrifugal pump unit, for example, via the display and control unit or the communication interface. However, the centrifugal pump unit can also determine the flushing volume itself by opening the flushing valve and measuring the time until the temperature no longer changes or the temperature change of the pumped water reaches or falls below a certain threshold, and then multiplying this time by the flow rate.This can be done, for example, once during the commissioning of the centrifugal pump unit.

[0042] It may also be provided that the centrifugal pump unit inhibits the activation of the flushing valve if sufficient dispensing activity has been detected at the consumer over a certain period of time, or if it receives a manual suppression command via the display and control unit or a remote suppression command via a communication interface, in particular a web interface.

[0043] In a further embodiment of the method, the centrifugal pump unit can additionally or alternatively be connected to at least one sensor and evaluate an electrical signal from this sensor. The evaluation can then determine whether the measured value detected by the sensor reaches a limit value or changes. Alternatively, the signal can form a setpoint that the centrifugal pump unit uses for its control.

[0044] The sensor could, for example, be a temperature sensor. Such a temperature sensor can be positioned downstream of a non-return valve, allowing the centrifugal pump unit to detect the status of the flushing valve.

[0045] Alternatively, the temperature sensor can be positioned downstream of a chiller, which is also hydraulically integrated into the circulation line to cool the drinking water. This allows the centrifugal pump unit to monitor the chiller and / or adjust its control accordingly. During operation, the temperature of the water downstream of the chiller should be lower than the temperature of the water flowing through the centrifugal pump unit. Furthermore, the centrifugal pump unit can adjust its flow rate based on the temperature downstream of the chiller, for example, increasing or decreasing the flow rate to maintain a constant temperature.

[0046] In a further variant of the method, it can additionally or alternatively be provided that the centrifugal pump unit opens the flush valve for flushing, closes it, then pumps the drinking water back into the circuit for a period of time, and then opens the flush valve again. Thus, the system is first flushed, then circulated, and then flushed again. This double flushing has the advantage that the water in a section between the flush valve and a main line, from which fresh drinking water flows into the circulation line, is also exchanged. This section is not flushed when the flush valve is open because it forms a hydraulic branch line to the main line.By circulating the water after the first flush, the volume of water in the section in question is forced into the main line or the circulation line, so that during the second flush, it is pushed by the fresh drinking water to the flushing valve and separated from the circuit there. For this reason, it is sufficient if the period for circulation before the second flush is between a few seconds and a few minutes, preferably no longer than 30 minutes, and in particular 15 minutes.

[0047] Preferably, double flushing is only performed during stagnation flushing, i.e., not during temperature flushing, since it is only necessary due to stagnation in the aforementioned section and leads to increased water consumption, which is unnecessary during temperature flushing. A single flush is sufficient for temperature flushing.

[0048] In another embodiment of the method, the centrifugal pump unit can additionally or alternatively be configured to detect a heat source (hot spot detection) that radiates heat into the drinking water supply network. This can be achieved by the centrifugal pump unit or its electronics performing the following steps: a. Switching off the pump unit to allow a locally limited volume in a section of the drinking water supply network adjacent to the heat source to be heated by the heat source when there is no circulation in the circulation line; b. Switching the pump unit back on after a certain period of time so that the drinking water circulates again in the circulation line; c. Monitoring the temperature of the pumped drinking water; d. Evaluating the temperature with regard to the occurrence of a local maximum; and e. Estimating the distance of the heat source to the centrifugal pump unit from the period between the pump unit being switched back on and the occurrence of the maximum, and the flow rate during this period.

[0049] As soon as the heated volume, which was previously located in the section of the drinking water supply network adjacent to the heat source, reaches the centrifugal pump unit, the temperature of the pumped water rises to a maximum and then falls again. The distance between the heat source and the centrifugal pump unit can be determined from the time between the pump restarting, or the start of circulation, and the occurrence of the maximum temperature, in conjunction with the flow rate during this period (e.g., in liters or m³ per hour). This distance can be expressed as "hot spot after x% of the pipe volume before the circulation system." Even such a rough guideline is helpful for the user. For a more precise distance calculation, it is important to know the pipe cross-section. If the cross-sections vary, an average value can also be used. For example, if the flow rate is...1.5 m / h, a 22x1 mm pipe has a flow velocity of 1.3 m / s. If the time to a local temperature maximum is 20 s, a hot spot is located 26 m upstream of the centrifugal pump unit.

[0050] According to another embodiment, the centrifugal pump unit, or rather its electronics, can selectively perform at least one of the following control modes: temperature control to maintain a constant drinking water temperature, flow rate control to maintain a constant flow rate in the circuit, and / or pressure control to maintain a constant or proportional pressure differential across the circuit. Temperature control is preferably based on the pump's internal temperature sensor, or alternatively, on an externally connected temperature sensor. The electronics adjust the pump unit's speed according to the temperature, for example, by increasing the speed as the temperature rises.The volume flow and pressure control can be carried out depending on the flow rate currently delivered by the centrifugal pump unit and / or the differential pressure (delivery head) it builds up, which is determined by the pump electronics, either by sensors or by calculation.

[0051] According to a further embodiment, it can be provided, additionally or alternatively, that the centrifugal pump unit controls a consumer with a flushing function, e.g., a tap connected to a branch line to the circulation line. This consumer can thus be triggered to flush the branch line, in particular simultaneously with the activation of the flushing valve.

[0052] According to another design variant, it can be additionally or alternatively provided that if the centrifugal pump unit determines that rinsing alone is insufficient to maintain a hygienically sound condition (e.g. due to the temperature), the centrifugal pump unit, or its pump electronics, can trigger the addition of disinfectants.

[0053] Compared to systems that work exclusively with disinfectants, this has the advantage that the amount of disinfectant added is lower.

[0054] Preferably, the centrifugal pump unit is part of a compact assembly within the drinking water supply network. This compact assembly has an inlet for receiving drinking water from the circuit and an outlet for pumping drinking water into the circuit, with the centrifugal pump unit positioned between the inlet and outlet to circulate the water. The compact assembly can include other components, eliminating the need for separate installation. The compact assembly can be used for both hot and cold water circulation systems.

[0055] It is advantageous if the flushing valve, which is part of a flushing unit, is also an integral component of the compact unit, and is therefore not located externally and away from the centrifugal pump or compact units used for circulation, as is usual in the prior art, thus reducing the effort required for the assembly or installation of the unit on site.

[0056] According to one embodiment, the pump unit, the electric motor, and the pump electronics form a single structural unit, with the pump electronics preferably being mounted externally on the electric motor, particularly on an axial end face. Such centrifugal pump units are generally known. However, the centrifugal pump unit according to the invention is specifically designed for use in a drinking water circulation system. The structural integration of all centrifugal pump components reduces the manufacturing effort required for the compact unit.

[0057] According to an alternative design variant, the pump electronics can be installed spatially independently of the electric motor, particularly when disconnected from the electric motor, within the compact unit. This has the advantage that it can be located at a different point than the pump unit, allowing for greater design flexibility in the compact unit and the spatial arrangement of its components.

[0058] In any case, the pump electronics are designed to control and energize the electric motor and to perform control or regulation of the electric motor and the pump unit. For this purpose, the pump electronics have a frequency converter and operating software that performs this control or regulation. According to the invention, the pump electronics are additionally equipped with a software component and a switching output controllable by this component, to which the flushing valve is connected for control purposes.

[0059] To enable adjustments to be made directly on the compact unit, the pump electronics can include a display and control unit. This can have a display for displaying information and at least one control element for making inputs. The control element can be a rotary and / or push-button. Alternatively, it can be a touch-sensitive surface of the display, with additional control elements optionally available. The display is advantageously a graphic color display.

[0060] The display and control unit can serve a variety of purposes. For example, it can be configured to accept a manual input of the trigger command for the flush valve. The display and control unit can also be used in the traditional way to configure the centrifugal pump unit, in this case in particular to configure the water circulation. For example, a specific control type and / or specific parameter or limit values ​​can be set. Alternatively, the display and control unit can be used to display information about the drinking water supply network, such as the water temperature or the volume flow of the circulating drinking water. Furthermore, errors or error states can be displayed on the display and control unit. Since the display and control unit is part of the centrifugal pump unit, all of the aforementioned options are carried out directly on the centrifugal pump unit.

[0061] The flushing valve can, for example, be a solenoid valve. In one design variant, the flushing unit can have an open outlet with a siphon. This open outlet prevents backflow contamination from the direction of the outlet. If necessary, the outlet and the siphon can also be integrated into the compact unit, such that these components of the flushing unit are enclosed within the housing of the compact unit.

[0062] Preferably, the flushing unit has a sensor that detects water in a section of the unit, particularly in the siphon, and is connected to the centrifugal pump unit or the pump electronics via a suitable interface. For example, the sensor can be a level sensor. This allows the centrifugal pump unit to monitor whether the water level in the siphon, possibly due to a blockage in the drain line, exceeds a certain threshold and threatens to overflow. Preferably, the centrifugal pump unit can close the flushing valve when water is detected or the water level is too high, thus preventing the flushing unit from overflowing.

[0063] In one design variant, it can be provided that the centrifugal pump unit or the pump electronics can be connected to a local or global data network such as an intranet, internet or building automation system via the communication interface and can be operated and / or queried remotely via this network. The communication interface can be a web interface or an industrial bus interface such as Modbus or Bacnet. In addition, the communication interface can be wired or a wireless interface such as Bluetooth, NFC, RFID or WLAN interface, etc. Such a wireless interface has the advantage that the centrifugal pump unit or the compact unit can be connected wirelessly to a portable external device such as a smartphone, laptop or tablet and can also be operated or queried via this device.

[0064] The communication interface is typically a combination of hardware and software to provide the necessary data communication and data processing, particularly protocols, on the one hand. The communication interface preferably includes a web server to access the centrifugal pump unit for operation and / or data retrieval via TCP / IP using a browser.

[0065] In one design variant, the centrifugal pump unit, or rather its electronics, can control a UV lamp. For this purpose, it can have a switchable output for connecting the UV lamp. Such a UV lamp serves to kill germs and can be integrated into the compact unit or located externally. The switching output can be controlled by the pump electronics and can be potential-free, for example, forming a relay output, or it can serve as a switchable power supply for the UV lamp.

[0066] In one version, the aforementioned limit values ​​and / or time periods can be parameters that can be specified to the pump electronics.

[0067] Further features, advantages, and effects of the invention are explained below with reference to exemplary embodiments and the accompanying figures. In the figures, identical or functionally equivalent elements retain the same reference numerals from figure to figure.

[0068] It should be noted that, in the context of this description, the terms "have," "comprise," or "include" in no way exclude the presence of other features. Furthermore, the use of the indefinite article for an object does not preclude its plural.

[0069] They show: Figure 1: an exemplary drinking water supply network with a circuit and a central circulation arrangement Figure 2: an exemplary implementation variant of the central circulation arrangement according to Figure 1According to the invention, Figure 3: a first embodiment of a compact unit according to the invention; Figure 4: a second embodiment of a compact unit according to the invention; Figure 5: a flowchart for double flushing; Figure 6: a flowchart for hot-spot detection

[0070] Figure 1illustrates an exemplary drinking water supply network 30 in a schematic representation. The drinking water supply network 30 is supplied with fresh drinking water via a house connection 28 by a water supplier, which delivers the drinking water at a specific temperature and a specific pressure. A main line 29 connects the house connection 28 to a circuit 31 formed by a circulation line (31), to which circuit a plurality of consumers 32 in the form of drinking water withdrawal points are connected. The withdrawal points here are, for example, a faucet on a washbasin, a bathtub fitting and a toilet. In this example, the circuit consists of several supply and return lines. The main line 29 initially flows into a central supply line 33, from which a first, second and third local supply line 34 branch off and connect the consumers 32 in the manner of a hydraulic series connection.At the end of the last consumer 32 in the series, the local supply lines each merge into a local return line 35. These local return lines 35 flow via a circulation valve 37 for hydraulic balancing of the local circuits 34, 35 into a common central return line 36, which in turn flows into a circulation arrangement A with a centrifugal pump unit 2, which pumps the return water back into the main line 29 and thus feeds it back into the circuit 31. In this way, the drinking water is continuously circulated to the consumers 32, so that inadmissible heat input in the individual pipes 33, 34, 35, 36 is minimized. The circulation arrangement A is shown in . Figure 1 represented as a black box, the implementation of which is based on a variant Figure 2 shows.

[0071] It should be noted that the drinking water supply network 30 can have a different hydraulic structure in another variant. For example, there can be a central circuit from which drinking water flows via a flow divider into a local supply line to the consumers and from the last consumer back to the flow divider via a local return line. The drinking water is then fed back into the central supply line via this return line, which at its end connects to a central return line that leads into the circulation system. According to another variant, the lines to the consumers can be simple dead-end lines, i.e., without a return line, with a water meter located at the beginning of each dead-end line serving one or more consumers.

[0072] Figure 2illustrates in schematic representation an implementation of the circulation arrangement A by a compact unit 1 according to the invention. The circulation arrangement A here comprises a section of the main line 29, the end of which opens into the circuit 31, which is shown here in simplified form by a single pipe and at the end again enters the circulation arrangement A.

[0073] The compact unit 1 has an inlet 3 for receiving drinking water from circuit 31 and an outlet 5 for supplying drinking water to circuit 31, the outlet 5 being connected to the main line 29. A centrifugal pump unit 2, comprising a pump unit 2a, an electric motor 2b driving the pump, and pump electronics 2c for controlling and regulating the electric motor 2b, is arranged between inlet 3 and outlet 5. Furthermore, a flushing valve 7a for draining drinking water from circuit 31 is hydraulically arranged between inlet 3 and outlet 5, in this embodiment being located between the centrifugal pump unit 2 and outlet 5. More precisely, it is located between the centrifugal pump unit 2 and a non-return valve 11, which prevents backflow of drinking water from the main line 29 via outlet 5 into the compact unit.

[0074] Another backflow preventer 11 is also arranged in the main line 29. The line between the backflow preventer 11 of the compact unit 1 and the main line 29 is hereinafter referred to as the intermediate line 16.

[0075] A central element of the compact unit 1 is the multi-way pipe section 10, which in this design variant has three connections and connects the flushing valve 7a, via which the centrifugal pump unit 2 is connected to the inlet 4 and, via the non-return valve, to the outlet 5. In more detail, it connects the centrifugal pump unit 2, the flushing valve 7a, and the non-return valve 11.

[0076] A manually operated inlet valve 4 is arranged between the centrifugal pump unit s and the inlet 4, which can be shut off if necessary.

[0077] The centrifugal pump unit 2 has a display and control unit 2d with a display 8, a control element 9, and a radio communication interface. Furthermore, the centrifugal pump unit 2 includes a temperature sensor 20 for measuring the temperature of the pumped drinking water and a flow rate measuring device 22. Thus, the centrifugal pump unit 2 is not only an actuator in the form of a pump, but also a sensor component within the compact unit 1.

[0078] The flushing valve 7a is a solenoid valve and is connected to the pump electronics 2c via a control line 13. In other words, the flushing valve 7a can be triggered by the pump electronics 2c. When the flushing valve 7a is closed, the centrifugal pump unit 2 pumps the drinking water from circuit 31 via the non-return valve 11 and the intermediate line 16 to the main line 26 and thus back into circuit 31. It should be noted that fresh drinking water only flows into circuit 31 via the main line 29 when water is removed from circuit 31, e.g., by a draw-off at one of the consumers 32 or by draining water as a result of an open flushing valve 7a. When triggered, the flushing valve 7a is open, so that the drinking water from circuit 31 flows into a free outlet 7b with a siphon 7c. Circuit 31 is thus largely emptied and filled with fresh drinking water.

[0079] Figure 3shows a more detailed view of a compact unit 1 according to a first embodiment of the invention in a schematic representation. As in Figure 2 As shown, the centrifugal pump unit 2 is located between the inlet 3 and the multi-way pipe section 10. The centrifugal pump unit 2 again consists of a pump unit 2a, an electric motor 2b driving it, and pump electronics 2c, which are attached to the electric motor 2b. The pump electronics 2c have a communication interface through which the centrifugal pump unit 2, and thus the compact unit 1, is connected via a communication line 17 to a building automation system, a local network, or the internet (www). The centrifugal pump unit 2 can thus be remotely controlled and / or queried.

[0080] The electric motor 2b is a wet-rotor motor, with its rotor rotating in a rotor chamber filled with the pumped drinking water. Flow channels between the pump chamber housing the impeller and the rotor chamber ensure a continuous flow through the rotor chamber. To prevent these flow channels from becoming clogged and consequently insufficient flow through the rotor chamber, which could lead to increased bacterial growth, a filter 19 is located upstream of the centrifugal pump unit 2 in the direction of flow. This filter removes coarse particles from the drinking water before they can enter the pump unit 2a. The filter 19 is located between the inlet valve 4 and the pump unit 2a.

[0081] The multi-way pipe section 10 is cross-shaped and thus has four connections 10a, 10b, 10c, 10d, each separated by a 90° angle. The pump unit 2a is connected to an inlet connection 10a of the multi-way pipe section 10. The flushing valve 7a is connected to a first outlet connection 10b on the opposite side. A second outlet connection 10c extends to the right, which is connected to the non-return valve 11 and leads to the outlet 5 of the compact unit 1. A manually operated outlet valve 6, analogous to the inlet valve 5, is arranged between the non-return valve 11 and the outlet 5. An intermediate line 16 connects the outlet 5 to the main line 29. On the left side, the multi-way pipe section 10 has a third outlet connection 10d, to which a sampling valve 18 is attached. This enables the taking of a drinking water sample for quality testing directly from the compact unit 1 according to the invention.

[0082] The flushing valve 7a is part of a flushing unit 7, which also includes a free outlet 7b, a siphon 7c, and an optional level sensor 7e. The flushing valve 7a is a solenoid valve and has an electromagnetic actuator 7d, which is connected to the pump electronics 2c via a control line 13. The pump electronics 2c can trigger the flushing valve 7a via the control line 13, causing the drinking water in circuit 31 to flow into the free outlet 7b. The free outlet 7b is open to the atmosphere to prevent germs from the drain or siphon 7c from entering circuit 31. The level sensor 7e monitors for a possible blockage-related overflow of the flushing unit 7. It is also connected to the pump electronics 2 via a sensor line 14.

[0083] An expansion module 15, which could be, for example, a cooling unit or a filter, is connected to output 5 of the compact unit 1. In the case of a cooling unit, pipe connections can point upwards or downwards. To allow installation in both cases, i.e., optionally in a normal orientation relative to the top and bottom, and in an upside-down orientation, the output connection 5 of the compact unit 1 is positioned laterally in the center.

[0084] The centrifugal pump unit 2 is designed to ensure the continuous circulation of drinking water in the circuit 31. For this purpose, the centrifugal pump unit 2 can maintain, and in particular regulate, its flow rate, delivery head, or differential pressure. During circulation operation, the drinking water enters the compact unit 1 via inlet 3 and flows through inlet valve 4 and filter 19 into the pump unit 2, which increases the pressure of the drinking water. Since the flushing valve 7 is closed, the drinking water flows from inlet port 10a to the second outlet port 10c of the multi-way pipe section 10 and through the non-return valve 11 and outlet valve 6 to outlet 5, from where it flows through intermediate line 16 to the main line 29 and then re-enters the circuit 31. A draw-off activity occurs when drinking water is drawn from one of the consumers 32.In this case, the pressure in the drinking water supply network and the volume flow delivered by the centrifugal pump unit 2 decrease and fresh drinking water flows from the house connection 28 via the main line 29 into the circuit 31.

[0085] The reduction in pressure and flow rate leads to a change in the operating point of the centrifugal pump unit 2. This is also detected by the centrifugal pump unit 2, as it must compensate for the deficit. A change in the operating point thus corresponds to a draw-off activity. For this purpose, the centrifugal pump unit has a flow rate or differential pressure measurement in the form of one or more sensors, or it calculates the flow rate or differential pressure in a known manner. The centrifugal pump unit 2, or rather its pump electronics 2c, is configured to detect and document every draw-off activity at the consumers 32, in particular to store it in a memory, e.g., in the form of an event.

[0086] If there is no tapping activity for an extended period, the non-replaced water is more likely to become contaminated. In this case, the drinking water in the circulation line should be replaced with fresh drinking water. Centrifugal pump unit 2 is configured to trigger flush valve 7a if there is no tapping activity or no change in the operating point for a certain period. This period is preferably between 24 and 72 hours. If tapping activity occurs, centrifugal pump unit 2 begins to wait for the period again.

[0087] Since it may happen that one or a few taps are insufficient to remove and replace the entire quantity of circulating drinking water, the centrifugal pump unit 2 can be additionally or alternatively configured, in addition to or as an alternative to the aforementioned tap-activity-dependent flushing criterion, to trigger the flushing valve 7a after a certain period of time. This period is, for example, 72 hours.

[0088] The centrifugal pump unit 2 has an internal temperature sensor 20, which determines the temperature of the pumped drinking water. The centrifugal pump unit also records this temperature by storing it over time. Advantageously, this can also be used to determine and document the temperature at which the water supplier provides the drinking water at the domestic water connection 28 by documenting the lowest temperature at the end of a flushing cycle (assuming that the heating of the water during flushing is negligible).

[0089] During circulation operation, the drinking water in circuit 31 can heat up, accelerating germ growth and potentially reaching temperatures that are unhygienically unacceptable. This heating process is monitored by the centrifugal pump unit 2. It triggers the flush valve 7a when the temperature of the pumped drinking water reaches or exceeds a limit, for example, 25°C. Since this limit may be exceeded at times, particularly during the summer months, it is also advisable in this case to override the temperature-dependent flush criterion with the time-dependent flush criterion, so that flushing always occurs every 72 hours.

[0090] Furthermore, the centrifugal pump unit 2 closes the flushing valve 7a when the level sensor 7e indicates that a limit level in the siphon 7c has been reached or exceeded, in order to prevent overflow. To ensure that the siphon 7c is always filled with water and thus a water seal is in place, the centrifugal pump unit 2 can perform a valve test in which the flushing valve 7a is briefly activated, for example for a few seconds, in particular 3 seconds, preferably at midnight.

[0091] As a result of the activation of the flush valve 7a, it opens and the drinking water is separated into the free outlet 7b. Since this is open to the atmosphere, the opening of the flush valve 7a essentially represents a hydraulic short circuit and the drinking water is separated at the pressure of the water supplier, approximately 2-6 bar, less the pipe losses in the drinking water network, and at maximum speed. However, a flow reducer can be arranged upstream or downstream of the flush valve 7a, which regulates a constant flow, for example, 10 l / min, regardless of the pressure. Since the drinking water to be separated in the design variant according to Figure 3As water flows through the centrifugal pump unit 2, it drives the pump unit 2a in a turbine-like manner, causing the electric motor 2b to operate as a generator. To prevent the DC link of the frequency converter in the pump electronics from being overloaded, the electric motor is switched off or not energized for a certain period. Furthermore, the centrifugal pump unit can monitor the separation or flushing process. As a result of this monitoring, the centrifugal pump unit 2 can apply a shutdown criterion, thus minimizing the amount of water that needs to be separated for flushing the circuit and consequently the economic loss of unused drinking water.

[0092] During water separation, its temperature can be measured by the pump's internal temperature sensor 20. Since fresh drinking water, which is generally at a significantly lower temperature, flows from the main line 29 into the circuit 31 and eventually reaches the centrifugal pump unit 2, the centrifugal pump unit 2 waits for this point and switches off the flushing valve 7a when the temperature reaches or falls below a target value, e.g., 20°C. Additionally, the centrifugal pump unit switches off the flushing valve 7a when the temperature no longer changes or no longer changes significantly, in other words, when it has reached a minimum value. This temperature-change-based switch-off criterion is superimposed on the previous temperature-based criterion and ensures that the flushing valve 7a is also switched off even if the temperature of the drinking water supplied by the water provider is above the target value.The water consumption for flushing remains minimal.

[0093] Alternatively, the flush valve 7a can be shut off when a predetermined amount of drinking water in liters or cubic meters, or drinking water for a specific period of time, has been drained. These criteria can also be used optionally in addition to or alternatively to the aforementioned criteria. Since the centrifugal pump unit 2 determines its currently pumped volume flow via the volume flow determination 22, it can function as a water meter by multiplying the volume flow from the time the flush valve is triggered by the time. The centrifugal pump unit 2 shuts off the flush valve 7a when the predetermined amount of drinking water has flowed through it.

[0094] The target value, quantity, and / or time period are parameters that can be predefined in the pump electronics. This takes into account the fact that the pump electronics cannot know the size of the drinking water supply network in which the compact unit is installed. However, the pump electronics are designed to automatically determine the quantity of drinking water to be drained or the time period for draining. This is achieved by measuring the time or the volume of water flowing through the centrifugal pump during an initial flush until the temperature drops to the minimum value. The resulting volume of water or the elapsed time can then be stored as a parameter for a quantity-based or time-based shutdown criterion in the pump electronics 2c.

[0095] The centrifugal pump unit 2 can detect the hydraulic short circuit resulting from the opening of the flushing valve 7a by a change in its operating point. From this, the centrifugal pump unit can recognize the proper functioning of the flushing valve 7a. If the electric motor is not powered during this time, the proper functioning of the flushing valve can be recognized by the fact that the pump speed is greater than zero, because water flows through the pump unit 2a and drives its impeller. Conversely, this means that the centrifugal pump unit 2 can conclude, or does conclude, that the flushing valve 7a is defective if, after the flushing valve 7a has been triggered, the expected change in the operating point or the positive pump speed does not occur despite the motor being switched off. The centrifugal pump unit 2 then issues an error message, for example via the display 8 or the communication interface.

[0096] The additional temperature sensor 21a, located downstream of the non-return valve 11, allows the pump electronics 2c to continuously monitor the status of the flushing valve 7a. This is particularly useful when the flushing valve 7a does not activate automatically. To determine this, the pump electronics 2c evaluates the temperature measured by the additional temperature sensor 21a by comparing it to its own internal temperature measurement. If the temperature measured by the additional temperature sensor 21a remains constant while the temperature measured by the pump's internal temperature sensor 20 decreases, the flushing valve 7a is clearly open and flushing is taking place (flushing mode). If, on the other hand, the two temperatures are the same, circulation is occurring (circulation mode).In combination with the knowledge that the flush valve 7a has been triggered, which the pump electronics 2c has in any case when it triggers the flush valve 7a itself, or alternatively receives information about it via the communication interface in the event of external triggering, the pump electronics 2c can even detect a fault in the flush valve 7a. If the temperatures remain the same after the flush valve 7a has been triggered, it is incorrectly closed. If the temperatures differ during circulation operation, water is obviously flowing out via the flush valve 7a, i.e. it is incorrectly opened. In all cases, the status, in particular a faulty state of the flush valve 7a, can be shown by the pump electronics 2c on the display 8, reported via the communication interface and / or stored in the pump electronics 2c so that it can be remotely retrieved.

[0097] An external sensor 21b is located in the expansion module 15 and is also connected to the pump electronics 2c via a sensor line 14. This allows the pump electronics 2 to monitor the expansion module 15 with respect to the measured value. If the expansion module 15 is a cooling unit, the external sensor 21b can be a temperature sensor that measures the temperature at the cooling unit's outlet. The centrifugal pump unit 2 can be configured to perform temperature control based on this temperature. Alternatively or additionally, if a limit value is exceeded, the centrifugal pump unit 2 can generate an error or warning message, which can be displayed on the display 8 or transmitted via the communication line 17 to indicate a fault in the cooling unit.

[0098] If the expansion module 15 is a filter, the external sensor 21b can be a differential pressure sensor that detects the pressure drop across the filter and thus indicates its degree of contamination. The centrifugal pump unit 2 can be configured to adapt its control based on this differential pressure, e.g., to increase the delivery head as the differential pressure increases in order to keep the speed of the circulating drinking water constant. Alternatively or additionally, if a limit value is exceeded, an error or warning message can be generated by the centrifugal pump unit 2 and shown on the display 8 or sent via the communication line 17 to indicate the need for filter maintenance or replacement.

[0099] Figure 4 shows another embodiment of a compact unit 1 according to the invention. It differs from the variant in Figure 3The key difference is that the centrifugal pump unit 2 is located not upstream of, but downstream of, the flushing valve 7a in the direction of flow; that is, it is positioned on the outlet side, not the inlet side. In other words, the flushing valve 7a is not located between the centrifugal pump unit 2 and the outlet 5, but between the inlet 3 and the centrifugal pump unit 2. This arrangement has the advantage that the centrifugal pump unit 2 is not overflowed during flushing, i.e., it is not driven by the potable water to be separated in a turbine-like manner. This is because the water in the intermediate line 16 remains stationary during flushing. Therefore, there is no risk of overloading the DC link of the frequency converter. Monitoring of the flushing process is only possible to a limited extent.

[0100] Therefore, to use a temperature- or temperature-change-based shutdown criterion for the flushing valve 7a, an additional temperature sensor 21a must be used between the inlet and the flushing valve 7a. Furthermore, the centrifugal pump unit 2 cannot function as a water meter here.

[0101] One advantage of the arrangement in Figure 4 However, the advantage is that the proper functioning of the backflow preventer 11 can be checked. If the centrifugal pump unit 2 detects a flow during the flushing activity, e.g., a speed other than zero despite the electric motor 2b being de-energized, it is concluded that the backflow preventer 11 is defective. The centrifugal pump unit 2 then issues an error message, for example, via the display 8 or the communication interface.

[0102] As in Figure 1As shown, in one embodiment, a temperature sensor 21c can be arranged in a line between the circulation line 31 and the consumer 32 and can detect a decentralized drinking water temperature. This decentralized temperature sensor 21c is connected to the pump electronics 2c so that it can determine whether the drinking water network is hydraulically balanced.

[0103] To do this, it compares the decentralized drinking water temperature with the central drinking water temperature, which is measured by the pump's internal temperature sensor 20, and assumes poor hydraulic balancing if the deviation between the decentralized and central drinking water temperatures exceeds a limit value of, for example, 2 K. If poor hydraulic balancing is detected, the centrifugal pump unit 2 issues an error message, for example, via the display 8 or the communication interface.

[0104] Figure 5Figure 1 shows a flowchart for implementing a double flush. The double flush serves to also exchange the water volume in the intermediate line 16, which remains in the intermediate line 16 during conventional flushing via the flushing valve 7a, since this forms a branch line due to the backflow preventer 11.

[0105] The procedure starts with circulation operation, in which the centrifugal pump unit 2 circulates the water in the circulation line 31, step S1. During circulation operation, it is continuously checked whether a condition exists for flushing the circulation line 31, step S2. Such a flushing condition could be, for example, that no or insufficient dispensing activity has been detected at consumers 32 for a certain period of time, or the temperature of the dispensed drinking water reaches or exceeds the upper limit of, for example, 25°C, or the temperature of the dispensed drinking water is above a certain limit of, for example, 23°C for a specified period of time, for example, 3 minutes, or a certain period of, for example, 72 hours has passed, or a certain date and / or a certain time has been reached, or a manual trigger command for flushing is received via the display and control unit 2d, or a remote trigger command for flushing is received via the communication interface, in particular the web interface.

[0106] If the condition is met, the flushing valve is opened in step S3 and the fresh drinking water flows through the main line 29 into the circulation line 31 or into the central supply line 33, the local supply lines 34, the local return lines 35 and the central return line 36, until it reaches the centrifugal pump unit 2 and the flushing valve 7a, where it is discharged.

[0107] During this flushing operation, a check is carried out to determine whether a condition for ending the flushing is fulfilled (step S4). Such a stop condition can be, for example, that the temperature of the pumped drinking water reaches or falls below a lower limit of e.g. 20°C, or the temperature no longer changes or the change in the temperature of the pumped drinking water falls below a limit, or a predefined flushing time has elapsed, or a predefined flushing volume has been drained.

[0108] If the condition is met, the flushing valve is closed in step S5 and the centrifugal pump unit 2 returns to circulation operation, step S6. However, this only lasts for a relatively short period of time, for example 60 seconds for about 50m of piping, so that the fresh drinking water can push the water volume from the intermediate line 16 into the main line 29 and, if necessary, into the circulation line 31.

[0109] Subsequently, the flushing valve 7a is opened again (step S7), so that the displaced water volume from the intermediate line 16, driven by the inflowing fresh water, also flows to the flushing valve 7a and is separated there. Thus, a water exchange takes place in the entire circulation line 31. During the flushing operation, it is checked again whether a condition for ending the flushing is met (step S8). Since the water already has its minimum temperature at the beginning of the flushing operation, the predefined flushing duration or the predefined flushing volume can be used as a stop condition. Alternatively, a modified temperature change condition can be used, in which the centrifugal pump unit first evaluates whether the water temperature rises and then falls again until the temperature no longer changes or the temperature change falls below the limit value.This is because the temperature increase is caused by the volume of water that was previously in the intermediate pipe.

[0110] If the condition is met, the flushing valve is closed again in step S9 and the centrifugal pump unit 2 returns to circulation mode, step S1.

[0111] Figure 5Figure 1 shows a flowchart for implementing hot-spot detection. This method serves to estimate the location of a heat source that causes an unusual heat input into the drinking water supply network 30. The location is determined by its distance from the centrifugal pump unit 2. Knowing the pipe lengths of the drinking water supply network 30, this distance can then be used to determine precisely where the heat source must be located within the building containing the drinking water supply network 30, what type of heat source it is, and whether the heat input into the drinking water supply network 30 caused by the heat source can be prevented.

[0112] For hot spot detection, the centrifugal pump unit or the pump electronics sequentially execute the following steps, starting from the circulation operation. Figure 6 illustrated steps from: S10 Switching off the pump unit 2a to allow a locally limited volume in a pipe section of the drinking water supply network 30, which is adjacent to the heat source, to be heated by the heat source in the absence of circulation in the circulation line 31, S11 Switching the pump unit 2a back on after a certain period of time so that the drinking water circulates again in the circulation line 31, S12 Monitoring the temperature of the pumped drinking water, S13 Evaluation of the temperature with regard to the occurrence of a local maximum, and S14 Estimation of the distance of the heat source to the centrifugal pump unit from the period from the switching on of the pump unit 2a until the occurrence of the maximum and the flow rate present during this period.

[0113] For example, if the period is 20 seconds, the distance between the heat source and the centrifugal pump unit can be determined as follows: A flow rate of 1.5 m3 / h, for example, with a pipe of 22x1 mm (20mm inner diameter) and a flow velocity of 1.3 m / s results in a distance of 26 m for 20 seconds. This distance can also be specified as "hot spot after x% of the pipe volume before the circulation system."

[0114] It should be noted that the foregoing description is given merely as an example for illustrative purposes and in no way limits the scope of protection of the invention. Features of the invention that are indicated as "may," "exemplary," "preferred," "optional," "ideal," "advantageous," "if applicable," or "suitable" are to be considered purely optional and likewise do not limit the scope of protection, which is defined exclusively by the claims. Insofar as the foregoing description mentions elements, components, process steps, values, or information that have known, obvious, or foreseeable equivalents, these equivalents are also encompassed by the invention.Likewise, the invention includes any changes, alterations or modifications of embodiments which involve the replacement, addition, modification or omission of elements, components, process steps, values ​​or information, as long as the basic idea of ​​the invention is retained, regardless of whether the change, alteration or modification leads to an improvement or deterioration of an embodiment.

[0115] Although the above description of the invention mentions a multitude of physical, non-physical, or method-related features in relation to one or more specific embodiments, these features can also be used in isolation from the specific embodiment, at least as long as they do not require the mandatory presence of further features. Conversely, these features mentioned in relation to one or more specific embodiments can be combined with each other as desired, as well as with other disclosed or undisclosed features of shown or not shown embodiments, at least as long as the features do not exclude each other or lead to technical incompatibilities. List of reference symbols

[0116] 1 Compact unit 2 Centrifugal pump unit 2a Pump unit 2b Electric motor 2c Pump electronics 2d Display and control unit 3 Inlet 4 Inlet valve 5 Outlet 6 Outlet valve 7 Flushing unit 7a Flushing valve 7b Free outlet 7c Siphon 7d Valve actuator 7e Sensor 8 Display 9 Control element 10 Multi-way pipe section 10a Inlet connection 10 Top outlet connection 10c Second outlet connection 10d Third outlet connection 11 Backflow preventer 12 Electrical supply line 13 Control line 14 Sensor line 15 Expansion module 16 Intermediate line 17 Communication line, bus 18 Sampling valve 19 Filter 20 Pump internal temperature sensor 21a, 21b Additional sensor 21c Decentralized temperature sensor 22 Flow rate determination 28 House connection for drinking water 29 Main line 30 Drinking water supply network 31 Circuit / Circulation line 32 Consumer 33 Central supply line 34 Local supply line 35 Local return line 36 Central return line 37 Circulation valve

Claims

1. A method for operating a water circulation in a drinking water supply network (30), which has at least one circuit (31) formed by a circulation line (31) for circulating drinking water, a centrifugal pump unit (2) for receiving drinking water from and conveying it into the circuit (31), and at least one consumer (32) fed with drinking water from the circuit (31), wherein the centrifugal pump unit (2) has a pump unit (2a), an electric motor (2b) driving it, and pump electronics (2c) for controlling and regulating the electric motor (2b), characterized in thatthe centrifugal pump unit (2) determines operating information about the water circulation or the drinking water supply network (30) and uses it to control the water circulation, wherein the centrifugal pump unit (2) controls a flushing valve (7a) connected to the circuit (31) to drain drinking water from the circuit (31), and - the centrifugal pump unit (2) triggers the flushing valve (7a) if - no or only insufficient tapping activity has been detected at the consumer (32) over a certain period of time, or - the temperature of the pumped drinking water reaches or exceeds an upper limit, or - the temperature of the pumped drinking water is above a certain limit for a predetermined period of time, or - a certain period of time has elapsed, or - a certain date and / or a certain time has been reached,or - it receives a manual trigger command for flushing via a display and control unit (2d) of the centrifugal pump unit (2), or - it receives a remote trigger command for flushing via a communication interface, in particular a web interface, and / or - the centrifugal pump unit (2) closes the flush valve (7a) when - the temperature of the pumped drinking water reaches or falls below a lower limit, or - the temperature no longer changes or the change in the temperature of the pumped drinking water falls below a limit, or - a predefined flushing duration has elapsed, or - a predefined flushing volume has been drained, and / or - the centrifugal pump unit (2) inhibits the triggering of the flush valve (7a) when - sufficient dispensing activity has been detected at the consumer (32) over a certain period of time,or - it receives a manual suppression command via a display and control unit (2d) of the centrifugal pump unit (2), or - it receives a remote suppression command via a communication interface, in particular a web interface, and / or - the centrifugal pump unit (2) opens the flushing valve (7a) for flushing, closes it, then pumps the drinking water back into the circuit (31) for a period of time, in particular from a few seconds to a few minutes, and then opens the flushing valve (7a) again.

2. Method at least according to claim 1, characterized in that the centrifugal pump unit (2) inhibits triggering of the flushing valve (7a) if at least the entire volume of the circuit (31), preferably at least 1.5 or 2 times the amount of water volume of the entire circulation line (31), has been replaced by fresh drinking water within 72 hours.

3. Method at least according to claim 1, characterized in thatthe centrifugal pump unit (2) switches off its electric motor (2b) after the flushing valve (7a) is triggered.

4. Method at least according to claim 1, characterized in that the centrifugal pump unit (2) determines its operating point during circulation and monitors it for changes, wherein the flushing valve (7a) is triggered if there is no change or insufficient frequency of changes in the specific period, in particular within 72 hours.

5. Method at least according to claim 1, characterized in that the centrifugal pump unit (2) determines the time elapsed since the last flushing during circulation and compares it with the determined period, whereby it triggers the flushing valve (7a) when the period, in particular 72 hours, has elapsed.

6. Method at least according to claim 1, characterized in that,if, after the flushing valve (7a) has been triggered, fresh drinking water flows into the circulation line (31) which already exceeds the upper limit, the triggering of the flushing valve (7a) is suppressed when the temperature of the pumped drinking water reaches or exceeds the upper limit and instead flushing is carried out regularly when a period of time has passed.

7. Method at least according to claim 1, characterized in that the centrifugal pump unit monitors during circulation whether two conditions are met simultaneously, namely whether the temperature limit is exceeded and whether this is the case for the duration of the specified period, the latter being recorded by a counter which is triggered when the temperature limit is reached or exceeded and is reset when the temperature of the pumped water falls below the limit again.

8. Method at least according to claim 1, characterized in thatthe centrifugal pump unit (2) determines the temperature gradient during flushing and evaluates it, whereby the centrifugal pump unit (2) stops flushing when the temperature gradient is zero or below the limit value.

9. Method at least according to claim 1, characterized in that the centrifugal pump unit (2) determines the amount of water drained during flushing based on its flow rate and compares it with the predefined flushing volume.

10. Method at least according to claim 1, characterized in that the centrifugal pump unit (2) determines the flushing duration or the flushing volume itself, for example once during commissioning by opening the flushing valve and determining the time until the temperature no longer changes or the change in the temperature of the pumped water reaches or falls below a limit value, whereby in the case of the flushing volume the time is multiplied by the flow rate.

11. Method at least according to claim 1, characterized in that the centrifugal pump unit (2) is connected to at least one temperature sensor and evaluates an electrical signal from this sensor, wherein the temperature sensor is arranged downstream of a cooling unit which is also hydraulically located in the circulation line (31) in order to cool the drinking water, and wherein the centrifugal pump unit (2) adapts its flow rate, in particular increases or reduces it, depending on the temperature downstream of the cooling unit in order to keep the temperature constant.

12. Method at least according to claim 1, characterized in thatthe centrifugal pump unit (2) detects a heat source that radiates heat into the drinking water supply network (30) by carrying out the following steps: a. switching off the pump unit (2a) in order to allow a locally limited volume in a pipe section of the drinking water supply network (30) that is adjacent to the heat source to be heated by the heat source in the absence of circulation in the circulation line (31), b. switching the pump unit (2a) back on after a certain period of time, c. monitoring the temperature of the pumped drinking water, d. evaluating the temperature with regard to the occurrence of a local maximum, and e. estimating the distance of the heat source to the centrifugal pump unit (2) from the period from the restart of the pump unit (2a) to the occurrence of the maximum and the flow rate present during this period.

13. Method at least according to claim 1, characterized in thatthe centrifugal pump unit (2) controls a consumer with a flushing function which is connected to a branch line to the circulation line (31), so that this consumer is caused to flush the branch line, in particular simultaneously with the triggering of the flushing valve.

14. Method at least according to claim 1, characterized in that the centrifugal pump unit (2), if it determines that the hygienically perfect condition cannot be maintained by flushing alone, triggers the addition of disinfectants.

15. Method at least according to claim 1, characterized in that the centrifugal pump unit (2) controls a UV lamp.

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