Method for operating and / or monitoring water circulation

Abstract

The invention relates to a method for operating and / or monitoring a water circulation in a drinking water supply network (30), which has at least one circuit (31) for circulating drinking water, a centrifugal pump unit (2) for receiving drinking water from and pumping it into the circuit (31), and at least one consumer (32) supplied 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), wherein the centrifugal pump unit (2) determines operating information about the water circulation or the drinking water supply network (30), and the operating information is used to control and / or monitor the water circulation.

Description

[0001] The invention relates to a method for operating and / or monitoring a water circulation in a drinking water supply network, which has at least one circuit 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 pump unit and pump electronics for controlling and regulating the electric motor.

[0002] The patent application US 2010 / 096018 A1 discloses a control of the water circulation, more precisely the water temperature of a hot water supply system, in which a higher-level control switches off a recirculation pump when a desired temperature, measured by a sensor in the pump, is reached within a recirculation loop.

[0003] Furthermore, German patent application DE3744102 A1 discloses a method for preventing ice formation in water pipes. A circulation pump cyclically circulates the water content of the domestic water system. The duration of the flow is selected so that the entire water content of a distribution pipe passes through the pump at least once, while the much longer pause interval is intended to be shorter than the time during which ice formation fills the entire cross-section of the pipe. A switching device is provided downstream of the timer switch for this program, which allows the pump to continue running even during the pause interval until ice formation has been reduced or eliminated. This activation is controlled by a thermostat that measures either the air temperature or the water temperature during the single circulation.

[0004] European patent application EP 3165510 A1 discloses a centrifugal pump unit with a device for detecting particles in liquids. This makes it possible to detect and monitor the quality of the liquid, particularly in the pumping of drinking water, but also in the pumping of other liquids. For example, knowing the type and quantity of bacteria or other particles present is important for drinking water quality.

[0005] Furthermore, European patent application EP 2365141 A2 relates to a drinking or service water system with a transfer point from a public supply network and at least one supply line for the water supply, as well as at least one ring line leading to at least one consumer, in which a ring line pump is provided. This ring line pump can generate a volume flow in the ring line leading to the supply line, which leads to a reliable and inevitable exchange of the volume in the ring line. Accordingly, stagnation can be avoided.

[0006] Drinking water supply networks in buildings serve to supply consumers with cold or hot drinking water via taps, toilets, or showers. To ensure the hygienic provision of drinking water, the proliferation of germs in the drinking water must be prevented. Depending on the consumer, how frequently the premises in which the consumer is located are used, and the part of the building in which they are located, water withdrawal occurs more or less regularly, or even infrequently. The result of irregular water withdrawal is stagnant water in the supply pipes to the consumers, which in turn promotes contamination with bacteria and viruses. This is particularly problematic 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.

[0007] 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 the circulating drinking water must be completely exchanged every 72 hours to replace unused drinking water in the circulation line with fresh, cold drinking water. The water exchange occurs by draining the water from the circulation line into a drain and no longer using it as drinking water.

[0008] 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 not more than 25°C to prevent the unacceptable proliferation of germs.

[0009] There are also temperature specifications for warm drinking water to prevent the unacceptable proliferation of germs, but these are minimum temperatures, as described in the DVGW W511 worksheet.

[0010] 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.

[0011] 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.

[0012] Against this background, it is the object of the present invention to provide a method for monitoring water circulation in a drinking water supply network, which ensures and / or monitors compliance with hygiene standards in the water circulation, can be set up with little assembly and cabling effort, and in particular exploits synergies of the individual components of the drinking water circulation.

[0013] This object is achieved by a method having the features of claim 1. Advantageous further developments are specified in the subclaims and are addressed below.

[0014] According to the invention, a method is proposed for operating and / or monitoring a water circulation in a drinking water supply network, which has at least one circuit for the circulation of drinking water, a centrifugal pump unit for receiving drinking water from and conveying 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 it and pump electronics for controlling and regulating the electric motor, determines operating information about the water circulation or the drinking water supply network and uses the operating information to monitor the water circulation and to monitor a valve within the circuit, and / or a filter in the circuit, and / or a control valve in the circuit, and / or a flushing valve connected to the circuit for draining drinking water from the circuit, and / or a backflow preventer connected in series with the centrifugal pump unit, and / or a backflow preventer located downstream of a flushing valve connected to the circuit, and / or a tapping activity at the consumer, and / or the drinking water supply network to determine whether there is a structural change to the drinking water supply network, and / or a faulty hydraulic balance, and / or a heat source radiating heat into the drinking water supply network, These monitoring cases are described in detail below.

[0015] The core of the invention is therefore to utilize an existing system component, namely the centrifugal pump unit or its pump electronics, in particular their intelligence and functionality, in maintaining and monitoring compliance with hygiene standards in drinking water supplies. This eliminates the need for higher-level central control electronics. Consequently, the effort required for installing and wiring the required sensors and, if necessary, actuators is also reduced, since the centrifugal pump unit itself functions as a sensor and, if necessary, also as an actuator, and the pump electronics act as the control unit for water circulation.

[0016] The method according to the invention can be used for both hot water and cold water circulation systems.

[0017] 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.

[0018] For example, the centrifugal pump unit can determine its flow rate, discharge head, differential pressure, or the temperature of the pumped water, and monitor for any changes or when a limit value is reached. This eliminates the need for separate sensors or sensor components such as a volume flow sensor, a pressure sensor, or a temperature sensor, which must be installed and wired into the drinking water supply network. Furthermore, the centrifugal pump unit can assess the current operating status, including the hygiene status of the water circulation or the drinking water network, and, if necessary, take appropriate measures to maintain drinking water hygiene. Finally, short-term and long-term changes in the operating status can also be detected.

[0019] 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.

[0020] The flow rate determined by the centrifugal pump unit determines the amount of water circulating in the circuit per unit of time. Furthermore, by determining the discharge head, it knows whether and to what extent a pressure drop exists along the circuit, i.e., whether one or more consumer taps are open. Finally, by measuring the temperature of the water flowing through them, the centrifugal pump unit can assess the temperature-related hygiene status of the drinking water supply network.

[0021] In one embodiment of the method, it can be provided that, if the flow falls below a lower limit, the centrifugal pump unit, or its pump electronics, assumes a closed valve within the circuit, which impairs or even prevents circulation. The closed valve can, for example, be a lockable service valve located upstream or downstream of the centrifugal pump unit to isolate a section of the drinking water network from the water supply. In this case, the centrifugal pump unit can suitably issue a corresponding message, in particular an error message, indicating the flow below a limit or the closed valve.

[0022] In a further embodiment of the method, it can additionally or alternatively be provided that the centrifugal pump unit carries out a long-term assessment of the condition of the drinking water supply network. The centrifugal pump unit can thus regularly determine its operating point at intervals of, for example, several hours to a few days, preferably every 24 hours, and monitor any changes to the operating point over the long term. This means that the operating point determined in each case is saved and compared with the last determined operating point or with several previous operating points. The operating point indicates the hydraulic resistance of the drinking water supply network. The determination is preferably always carried out at night at a fixed time, for example between midnight and 4 a.m., to ensure that no consumer is drawing water from the circuit line during the determination.

[0023] The evaluation of a change in the operating point can be performed in various ways. For example, the centrifugal pump unit, or rather the pump electronics, can be configured to assume a structural change in the drinking water supply network (system change) if the operating point changes abruptly, i.e., if a newly determined operating point deviates significantly from the previous operating point(s), for example, if at least one of the variables defining the operating point has changed by more than 30% or even more than 50% compared to its previous value. This is because the determined operating point should always remain the same when no water is drawn from a consumer.A structural change in the drinking water supply network in the form of an extension, shortening, change in the diameter of the pipe routes or even the replacement of components such as valves, on the other hand, leads to a different hydraulic resistance of the drinking water supply network, which is noticeable in a significant change in the operating point.

[0024] The operating point of a centrifugal pump unit is considered to be the combination of at least two independent physical variables of the centrifugal pump unit, preferably the flow rate (volume flow) and the head (differential pressure). Alternatively, the operating point can be defined by flow rate and speed, speed and head, power and flow, current consumption and flow, speed and torque, or any two other variables of the centrifugal pump unit.

[0025] Additionally or alternatively, the centrifugal pump unit, or rather the pump electronics, can assume that the filter in the circuit is clogged if the differential pressure of the centrifugal pump, which also defines the operating point, gradually increases, i.e., from a determined operating point to another, or rises above a limit. A filter in the circuit can become increasingly clogged due to particles carried along in the water, so that the pressure drop across the filter gradually increases. This also becomes noticeable in the operating point of the centrifugal pump unit, since a higher pressure is required to deliver the same flow rate.

[0026] Furthermore, it can be additionally or alternatively provided that the centrifugal pump unit, or rather the pump electronics, assumes a defective open control valve in the circuit if the differential pressure, which also defines the operating point, gradually decreases or falls below a limit. The control valve can be a valve that defines a partial flow of the circulating drinking water in a branch of the circuit line to which one or more consumers are connected. Detecting such a defect in the drinking water supply network is particularly important, since in this case, the hydraulic balance of the network is no longer ensured and other lines could be undersupplied.

[0027] In all the aforementioned cases, the centrifugal pump unit can suitably issue a corresponding message, in particular an error message, which indicates, for example, the change in the drinking water supply network, or the differential pressure increase or the limit value being exceeded or the need for filter cleaning or filter replacement, or the differential pressure drop or the limit value being undershot or the need for repair of the control valve.

[0028] In one variant, the centrifugal pump unit can be arranged upstream of a flush valve connected to the circuit for draining water from the circuit. This has the advantage that the drinking water flowing in from the circuit, which is to be separated via the flush valve, flows through the centrifugal pump and can thus be monitored or measured by the centrifugal pump in various ways, for example, with regard to temperature, flush volume, flow velocity, etc.

[0029] In addition to circulation or circulation operation, flushing operation represents another operating mode of the drinking water supply network or the pump unit. During flushing operation, the pump unit is suitably switched off, since the water automatically flows to the flush valve due to the atmospheric pressure behind it.

[0030] 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.

[0031] In another design variant, the centrifugal pump unit can be arranged downstream of a flush valve connected to the circuit for draining water from the circuit. This has the advantage that the drinking water to be separated via the flush valve does not flow through the centrifugal pump and the centrifugal pump is therefore not overflowed when the flush valve is open, i.e. the impeller of the centrifugal pump is not driven by the water being drained and flowing in from the circuit and the electric motor therefore does not run in generator mode, which requires special measures to prevent overloading the frequency converter of the pump electronics. With such an arrangement, the centrifugal pump unit is also de-energized during flushing operation. In addition, it can be provided that the centrifugal pump unit determines whether its speed is greater than zero when de-energized in order to check a backflow preventer.The backflow preventer prevents fresh drinking water from flowing against the intended circulation direction when the flush valve is open and being separated via the flush valve. During flushing, the centrifugal pump unit, particularly the pump electronics, may assume that a backflow preventer in series with the centrifugal pump unit, particularly a backflow preventer located between the flush valve and the centrifugal pump unit, is defective if the speed is greater than zero.

[0032] Determining the rotational speed is possible using a known, state-of-the-art method. 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, impeller rotation 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. A change in the magnetic field indicates rotor rotation.

[0033] The driveless state is a state in which the electric motor is de-energized, meaning no electrical torque acts on the rotor. In other words, the electric motor is switched off.

[0034] Suitably, the centrifugal pump unit can also issue a corresponding message in the three cases mentioned above, in particular an error message, which indicates, for example, an open or defective flushing valve or a defective backflow preventer.

[0035] In a further embodiment of the method, it can additionally or alternatively be provided that the centrifugal pump unit carries out a short-term assessment of the condition of the drinking water supply network. The centrifugal pump unit can thus determine its operating point continuously or quasi-continuously and monitor any change in the operating point so that short-term changes can be detected. This means that the operating point determined in each case is saved and compared with the last determined operating point or with several past operating points. A quasi-continuous determination occurs when the operating point is determined in discrete time steps, e.g. at intervals of one millisecond to a few or tens of seconds. For example, it can be provided that the centrifugal pump unit, or rather the pump electronics, assumes a tapping activity at the consumer when the operating point changes.A tapping activity occurs when water is drawn from the circuit line by at least one consumer. Fresh drinking water then flows into the circuit line, provided, for example, by a water supplier at a house connection.

[0036] 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.

[0037] Determining the frequency of water withdrawals within a certain period of time, the duration of the individual or total water withdrawal(s) and / or the withdrawal intensity, i.e. the number of consumers open at the same time, has the advantage that the centrifugal pump unit or the pump electronics can evaluate the amount of water exchanged in the circuit 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 of time is sufficiently high to maintain drinking water hygiene. This has the advantage that unnecessary flushing can be prevented and water can therefore be saved. Sufficient water withdrawal or sufficient withdrawal activity occurs at least when the entire water content of the circuit line has been withdrawn within 72 hours, i.e. at least the entire volume of the circuit line has been replaced with fresh drinking water.

[0038] 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 circuit has actually been replaced with fresh water, because during one or more water withdrawals, freshly flowing water may have been withdrawn instead of the old water. Thus, even if a water volume equivalent to the contents of the circuit is exchanged, a residual portion of old water may still remain in the circuit. For this reason, it is advantageous to suppress flushing only when at least 1.5 or 2 times the water volume of the entire circuit has been withdrawn within 72 hours.

[0039] Preferably, the centrifugal pump unit, or rather the pump electronics, can be provided to document every dispensing activity, preferably also its duration and / or intensity. This information can thus be retrieved retrospectively from the centrifugal pump unit at any time.

[0040] In a further embodiment of the method, it can be provided, additionally or alternatively, that the centrifugal pump unit, or rather the pump electronics, controls a flush valve connected to the circuit to drain water from the circuit. Thus, the centrifugal pump unit not only monitors the water circulation and the drinking water network, but can also initiate measures to ensure drinking water hygiene. This can be done in different ways, both with regard to initiating a flush and with regard to its termination. To save energy, the centrifugal pump unit can switch off its electric motor after the flush valve is triggered.

[0041] For example, the centrifugal pump unit, or rather the pump electronics, can trigger the flush valve if no or only insufficient drawing activity has been detected at the consumer over a certain period of time. This can be referred to as stagnation flushing. In this case, no or not enough water has been drawn from the circuit line and replaced with fresh drinking water within the period, and germs can grow in the old, 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 if changes do not occur frequently enough, the flush valve can be triggered. The period could be 72 hours, for example. However, if sufficient drawing activity has been detected, the flush valve does not need to be triggered, thus minimizing the amount of water to be separated.

[0042] Alternatively, the centrifugal pump unit, or rather the pump electronics, can trigger the flush valve, especially regularly after a certain period of time has passed, for example, every 72 hours. This can also be referred to as stagnation flushing. The centrifugal pump unit then determines the time elapsed since the last flush during circulation and compares it with the specified period. This ensures that, regardless of a specific condition, the water in the entire circuit is always replaced with fresh drinking water after the specified period has elapsed.

[0043] 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 circuit line flows to the flush valve and is separated there. Fresh, cooler drinking water then generally flows into the circuit line, for example, with a maximum temperature of 16°C. This ensures that the water in the circuit line does not heat up to a temperature that promotes germ formation.

[0044] 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.

[0045] The aforementioned limit value can be a maximum temperature which, when reached or exceeded, immediately triggers a temperature flush by the centrifugal pump unit. According to a further alternative, the centrifugal pump unit, or rather the pump electronics, can trigger a temperature flush at a lower temperature if this temperature is exceeded for a certain period of time. The flush valve is therefore triggered when the temperature of the pumped water remains above a certain limit value for a predetermined period of time. This limit value can be, for example, 23°C and the period of time can be 3 minutes. In this case, the centrifugal pump unit monitors whether two conditions are met simultaneously during circulation: whether the temperature limit value has been exceeded and whether this is the case for the duration of the specified period of time.The latter can be recorded by a counter that is triggered when the temperature limit is reached or exceeded. If the temperature of the pumped water drops below the limit again, the counter can be reset.

[0046] 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.

[0047] According to a further 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.

[0048] 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.

[0049] Although the aforementioned flush-triggering conditions are alternatives, two or more of them can be active and monitored simultaneously to monitor drinking water hygiene in multiple respects.

[0050] As mentioned previously, the end of a rinsing process can also be achieved in different ways.

[0051] For example, the centrifugal pump unit, or rather the pump electronics, closes the flush valve when the temperature of the pumped water reaches or falls below a lower limit. The centrifugal pump unit then measures the temperature during flushing and compares it with the lower limit. As soon as the fresh drinking water flowing into the circuit 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.

[0052] 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. 0.1K / 60s, the centrifugal pump unit can assume that the circuit line has been completely flushed and end the flushing.Compared to the use of a lower temperature limit, this has the advantage that the flushing is not terminated too early and the termination becomes dependent on the temperature at which the supplier supplies the drinking water.

[0053] According to a further alternative, the centrifugal pump unit, or rather the pump electronics, can close the flushing valve when a predefined flushing time has elapsed. In this case, the centrifugal pump unit determines the period of time since the flushing valve was triggered and compares it with the predefined flushing time. This flushing time corresponds at least to the time required to exchange the water volume in the circulation line. 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 time itself 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. This can be done once, for example, when the centrifugal pump unit is commissioned.

[0054] According to a further alternative, the centrifugal pump unit, or rather the pump electronics, can close the flush valve when a predefined flush volume has been drained. The centrifugal pump unit then determines the amount of water drained during flushing based on its flow rate and compares it with the predefined flush volume. This flush volume corresponds at least to the water volume contained 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 flush volume itself by opening the flush 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, and then multiplying this time by the flow rate.This can be done once, for example, when commissioning the centrifugal pump unit.

[0055] It can further be provided that the centrifugal pump unit inhibits the triggering of the flushing valve if sufficient tapping 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.

[0056] In a further embodiment of the method, it can additionally or alternatively be provided that the centrifugal pump unit is connected to at least one sensor and evaluates an electrical signal from this sensor. The evaluation can be based on whether the measured value detected by the sensor reaches a limit or changes. Alternatively, the signal can form a setpoint specification that the centrifugal pump unit uses for its control.

[0057] The sensor can be a temperature sensor, for example. Such a temperature sensor can be installed behind a backflow preventer so that the centrifugal pump unit can detect the status of the flush valve. This will be described below.

[0058] Alternatively, the temperature sensor can be located downstream of a cooling unit, which is also hydraulically connected to the circuit to cool the drinking water. This allows the centrifugal pump unit to monitor the cooling unit and / or adjust its control if necessary. When the cooling unit is in operation, the temperature of the water downstream of the cooling unit should be lower than the temperature of the water flowing through the centrifugal pump unit. If this is not the case, which the centrifugal pump unit can determine by comparing the two temperatures, it can issue a corresponding message and indicate a cooling unit defect. Furthermore, the centrifugal pump unit can adjust its flow rate depending on the temperature downstream of the cooling unit, for example, increasing or reducing the flow rate depending on the temperature in order to keep the temperature constant.

[0059] According to another alternative, the temperature sensor can be installed in a line between the circuit line and the consumer and measure a decentralized drinking water temperature. This has the advantage that the centrifugal pump unit can detect a missing or poor hydraulic balance and indicate this by issuing a corresponding message, as described below.

[0060] In another design variant, the sensor can be a differential pressure sensor. Such a sensor can, for example, measure the pressure difference across a drinking water filter, which is also hydraulically connected to the circuit line to filter the drinking water. The centrifugal pump unit can compare the pressure difference with a limit value and, if the limit value is reached or exceeded, issue a message indicating that the filter is too clogged and needs to be cleaned or replaced.

[0061] In a further embodiment of the method, it can additionally or alternatively be provided that the centrifugal pump unit records the temperature of the water in the flow direction upstream of a flush valve connected to the circuit and downstream of a backflow preventer located behind the flush valve and compares the recorded temperature values. Since the temperatures must be the same during circulation operation, i.e. when the flush valve is closed, the centrifugal pump unit or the pump electronics can assume, in the case of unequal temperature values, that the flush valve is open or has not closed properly after a flush and is therefore defective. Conversely, the centrifugal pump unit or the pump electronics can assume, in the case of identical temperature values ​​with the flush valve open, i.e.During flushing, one might assume that the backflow preventer is defective because fresh drinking water is clearly flowing through the backflow preventer to the flush valve, which is precisely what the backflow preventer is designed to prevent. However, during proper operation of the backflow preventer, the water temperature downstream of the backflow preventer should be higher than in the centrifugal pump unit as soon as the fresh drinking water arrives there, since the backflow preventer is located in a section that is not flushed during flushing.

[0062] Suitably, the centrifugal pump unit can also issue a corresponding message in the two aforementioned cases, in particular an error message, which indicates, for example, an open or defective flushing valve or a defective backflow preventer.

[0063] As previously noted, the centrifugal pump unit can determine whether the drinking water network is hydraulically balanced based on at least one decentralized drinking water temperature in a local circuit fed from the circuit in which the centrifugal pump unit pumps the water. A lack of or poor hydraulic balance exists if the decentralized temperature deviates significantly from the central temperature of the water flowing through the centrifugal pump unit. The latter can be determined by the centrifugal pump unit, in particular an internal temperature sensor, or by a temperature sensor connected to the centrifugal pump unit. The centrifugal pump unit can receive the decentralized temperature either directly from a connected temperature sensor or as a measured value via the communication interface.It then compares at least one decentralized drinking water temperature with the central drinking water temperature and assumes an incorrect hydraulic balancing if a deviation between the decentralized and central drinking water temperatures exceeds a limit value, for example 2 K.

[0064] 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 is also exchanged in a section between the flush valve and a main line, from which fresh drinking water flows into the circuit line. 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 water volume in that section is forced into the main line or the recirculation line, so that during the second flush, it is pushed by the fresh drinking water to the flush valve and separated from the circuit. For this reason, it is sufficient if the circulation period before the second flush is between a few seconds and a few minutes, preferably no longer than 30 minutes, especially 15 minutes.

[0065] Preferably, double flushing is performed only during stagnation flushing, i.e., not during temperature flushing, since it is only necessary due to stagnation in the aforementioned section and results in increased water consumption, which is not necessary during temperature flushing. With temperature flushing, a single flush is sufficient.

[0066] In a further embodiment of the method, it can additionally or alternatively be provided that the centrifugal pump unit detects a

[0067] A heat source (hot spot detection) that radiates heat into the drinking water supply network can be detected. This can be achieved by the centrifugal pump unit or pump electronics performing the following steps: a. Switching off the pump unit in order to allow a locally limited volume in a pipe section of the drinking water supply network that is adjacent to the heat source to be heated by the heat source in the absence of circulation in the circuit, b. Switching the pump unit back on after a certain period of time so that the drinking water circulates again in the circuit, c. Monitoring the temperature of the pumped drinking water, d. Evaluation of the temperature with regard to the occurrence of a local maximum, and e. Estimation of the distance of the heat source to the centrifugal pump unit from the time between the pump unit being switched on again and the occurrence of the maximum and the flow rate during this period.

[0068] As soon as the heated volume, which was previously located in the pipe 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 drops again. The distance between the pump being switched on again, or the start of circulation, and the occurrence of the maximum, in conjunction with the flow rate that occurred during this period (e.g., in liters or m3< per hour), can be used to determine the distance between the heat source and the centrifugal pump unit. This distance can be specified in the form of "hot spot after x% of the pipe volume upstream of the circulation system." Even such a rough orientation is helpful for the user. For a more specific distance specification, it is important that the pipe cross-section is known. For different cross-sections, an average value also works. If the flow rate is, for example,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.

[0069] According to a further embodiment, the centrifugal pump unit, or rather the pump electronics, can optionally execute at least one of the following control types of the centrifugal pump unit: temperature control to maintain the drinking water temperature constant, volume flow control to maintain the volume flow in the circuit constant, and / or pressure control to maintain the pressure difference across the circuit constant or proportional pressure control. Temperature control is preferably carried out as a function of the pump's internal temperature sensor, or alternatively as a function of the connected temperature sensor. The pump electronics adjusts the speed of the pump unit depending on the temperature, for example, such that the higher the temperature, the higher the speed.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.

[0070] According to a further embodiment, it can additionally or alternatively be provided that the centrifugal pump unit determines its flow rate and, after triggering the flush valve, assumes a flush valve defect if the flow rate does not increase. However, this requires that the differential pressure between the circuit line and the flush valve outlet is lower than the differential pressure previously generated by the centrifugal pump unit. With the aid of a flow limiter, the differential pressure to the flush valve outlet can be increased, thus limiting the volume flow of the outflowing water. In this case, a flush valve defect can be detected, as described above, preferably via the speed of the pump unit or the temperature difference across the backflow preventer. The centrifugal pump unit preferably issues a message about this flush valve defect.

[0071] All of the aforementioned messages can be displayed by the centrifugal pump unit, for example, on a control unit display and / or acoustically. Alternatively or additionally, each message can be sent via the communication interface, for example, to a building management system, a remote server of a monitoring center, or a mobile device. Furthermore, each message can be stored as an error or warning in the pump electronics, particularly in a web interface, so that all messages can be retrieved via a communications network connected to the communication interface.

[0072] According to a further embodiment, it can additionally or alternatively be provided 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.

[0073] According to a further design variant, it can be provided additionally or alternatively that if the centrifugal pump unit determines that hygienically perfect conditions cannot be maintained by flushing alone (e.g., due to the high temperature), the centrifugal pump unit, or its pump electronics, can trigger the addition of disinfectant. Compared to systems that operate exclusively with disinfectants, this has the advantage that the added amount of disinfectant is lower.

[0074] Preferably, the centrifugal pump unit is part of a compact unit within the drinking water supply network. This compact unit has an inlet for receiving drinking water from the circuit and an outlet for pumping drinking water into the circuit. The centrifugal pump unit is located between the inlet and outlet to pump the water in the circuit. The compact unit can incorporate additional components, eliminating the need for separate installation. The compact unit can be used for both hot and cold water circulation systems.

[0075] It is advantageous if the flushing valve, which is part of a flushing unit, is also an integral part of the compact unit and is therefore not arranged externally and away from the centrifugal pump or compact units used for circulation, as is usual in the state of the art, so that the effort for assembly or installation of the unit on site is reduced.

[0076] 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 attached externally to the electric motor, in particular to an axial end face. Centrifugal pump units of this type are generally known. However, the centrifugal pump unit according to the invention is specifically designed for use in a drinking water circulation system. By structurally combining all centrifugal pump components, the cost of manufacturing the compact unit is reduced.

[0077] According to an alternative design variant, the pump electronics can be installed in the compact unit spatially independent of the electric motor, particularly when removed from the electric motor. This has the advantage that it can be arranged at a different location than the pump unit, allowing greater design flexibility in the design of the compact unit and the spatial arrangement of its components.

[0078] In any case, the pump electronics are intended to control or energize the electric motor, as well as to perform control or regulation of the electric motor and the pump unit. For this purpose, the pump electronics incorporates 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 that can be controlled by this software component, to which the flush valve is connected for control purposes.

[0079] 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.

[0080] 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.

[0081] The flushing valve can be a solenoid valve, for example. In one design variant, the flushing unit can have an outlet open to the atmosphere with a siphon. This open outlet prevents recontamination from the direction of the outlet. If necessary, the outlet and siphon can also be integrated into the compact unit, in such a way that these components of the flushing unit are enclosed by a housing of the compact unit.

[0082] The flushing unit preferably has a sensor that detects water in a sub-area of ​​the flushing unit, particularly in the siphon, which is connected to the centrifugal pump unit or the pump electronics via a corresponding interface. For example, the sensor can be a level sensor. This allows the centrifugal pump unit to monitor whether water in the siphon exceeds a certain threshold level, possibly due to a blockage in the drain line, and the siphon threatens to overflow. Preferably, it can be provided that the centrifugal pump unit closes the flushing valve if water is detected or if the water level is too high, to prevent the flushing unit from overflowing.

[0083] 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.

[0084] 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.

[0085] In one embodiment, the centrifugal pump unit, or rather the pump electronics, can be configured to 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 also be part of the compact unit or located externally. The switching output can be switched by the pump electronics and can be potential-free, for example, forming a relay output, or serving as a switchable power supply for the UV lamp.

[0086] In one embodiment, the previously mentioned limit values ​​and / or time periods may be parameters that can be specified for the pump electronics.

[0087] 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.

[0088] 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.

[0089] 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 flow chart for double rinsing Figure 6: a flow chart for hot spot detection

[0090] 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 from 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 (circulation line), to which several 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 faucet, 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.

[0091] It should be noted that in another variant, the drinking water supply network 30 may have a different hydraulic structure. For example, there may 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. Via this, the drinking water is fed back into the central supply line, which at its end merges into a central return line that flows into the circulation arrangement. According to a further variant, the lines to the consumers may be pure branch lines, i.e., without a return line, with a water meter located at the beginning of each branch line to one or more consumers.

[0092] 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.

[0093] The compact unit 1 has an inlet 3 for receiving drinking water from the circuit 31 and an outlet 5 for pumping drinking water into the circuit 31, wherein the outlet 5 is connected to the main line 29. Between the inlet 3 and the outlet 5 is arranged a centrifugal pump assembly 2 with a pump unit 2a, an electric motor 2b driving the pump assembly, and pump electronics 2c for controlling and regulating the electric motor 2b. Furthermore, a flush valve 7a for draining drinking water from the circuit 31 is hydraulically arranged between the inlet 3 and the outlet 5, wherein in this embodiment it is located between the centrifugal pump assembly 2 and the outlet 5. More precisely, it is located between the centrifugal pump assembly 2 and a backflow preventer 11, which prevents backflow of drinking water from the main line 29 via the outlet 5 into the compact unit.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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 detecting the temperature of the pumped drinking water and a volume flow rate determination 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.

[0098] The flush valve 7a is a solenoid valve and is connected to the pump electronics 2c via a control line 13. In other words, the flush valve 7a can be triggered by the pump electronics 2c. When the flush valve 7a is closed, the centrifugal pump unit 2 pumps the drinking water from the circuit 31 via the backflow preventer 11 and the intermediate line 16 to the main line 26 and thus back into the circuit 31. It should be noted that fresh drinking water only flows into the circuit 31 via the main line 29 when water is removed from the circuit 31, e.g. by withdrawal from one of the consumers 32 or by draining water as a result of an open flush valve 7a. When triggered, the flush valve 7a is open, so that the drinking water flows from the circuit 31 into a free outlet 7b with a siphon 7c. Circuit 31 is thus largely emptied and filled with fresh drinking water.

[0099] 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. Here, the centrifugal pump unit 2 also consists of the structural combination of a pump unit 2a, an electric motor 2b driving it, and pump electronics 2c, which is attached to the electric motor 2b. The pump electronics 2c has a communication interface with which the centrifugal pump unit 2 and thus the compact unit 1 are connected via a communication line 17 to a building automation system, a local network, or the Internet (www). In this way, the centrifugal pump unit 2 can be remotely controlled and / or remotely interrogated.

[0100] The electric motor 2b is designed as a wet rotor, 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 continuous flow through the rotor chamber. To prevent these flow channels from becoming clogged and consequently preventing sufficient flow through the rotor chamber, which could lead to increased germ formation, 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.

[0101] The multi-way pipe section 10 is cross-shaped here and thus has four connections 10a, 10b, 10c, 10d, each of which is at 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 an opposite first outlet connection 10b. To the right side, a second outlet connection 10c branches off, which is connected to the backflow preventer 11 and leads to the outlet 5 of the compact unit 1. Between the backflow preventer 11 and the outlet 5, a manually operable outlet valve 6 is arranged analogous to the inlet valve 5. An intermediate line 16 connects the outlet 5 to the main line 29. To the left side, the multi-way pipe section 10 has a third outlet connection 10d, to which a sampling valve 18 is arranged. This enables the taking of a drinking water sample for quality testing directly from the compact unit 1 according to the invention.

[0102] The flush 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 flush 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 flush valve 7a via the control line 13, so that the drinking water in the circuit 31 flows 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 the circuit 31. The level sensor 7e monitors a possible overflow of the flushing unit 7 due to a blockage. It is also connected to the pump electronics 2 via a sensor line 14.

[0103] An expansion module 15, which can be, for example, a cooling unit or a filter, is connected to the outlet 5 of the compact unit 1. In the case of a cooling unit, pipe connections can lead upwards or downwards. To enable installation in both cases, i.e., either in a normal orientation relative to the top and bottom or in an upside-down orientation, the outlet connection 5 of the compact unit 1 is arranged centrally on the side.

[0104] The centrifugal pump unit 2 is designed to ensure that the drinking water continuously circulates in the circuit 31. To this end, the centrifugal pump unit 2 can maintain, in particular regulate, its volume flow or its delivery head or differential pressure constant. In circulation mode, the drinking water enters the compact unit 1 via the inlet 3 and flows through the inlet valve 4 and through the filter 19 into the pump unit 2, which increases the pressure of the drinking water. Since the flush valve 7 is closed, the drinking water flows from the inlet connection 10a to the second outlet connection 10c of the multi-way pipe section 10 and through the backflow preventer 11 and the outlet valve 6 to the outlet 5, from where it flows through the intermediate line 16 to the main line 29 and then re-enters the circuit 31. Drawing 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.

[0105] A 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, especially since it must compensate for the deficit. A change in the operating point thus corresponds to a tapping activity. For this purpose, the centrifugal pump unit has a volume flow or differential pressure determination device in the form of one or more sensors, or calculates the volume flow or differential pressure mathematically in a conventional manner. The centrifugal pump unit 2 or its pump electronics 2c is configured to detect and document each tapping activity at the consumers 32, in particular to store it in a memory, e.g., in the form of an event.

[0106] 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 has been 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.

[0107] Since it may happen that one or a few tapping activities are too low to remove the entire amount of circulating drinking water and replace it with fresh water, the centrifugal pump unit 2 can be configured, in addition to or as an alternative to the aforementioned tapping activity-dependent flushing criterion, to trigger the flush valve 7a after a certain period of time. This period is, for example, 72 hours.

[0108] 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).

[0109] 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.

[0110] Furthermore, the centrifugal pump unit 2 closes the flush valve 7a when the level sensor 7e indicates that a limit level in the siphon 7c has been reached or exceeded, to prevent overflow. To ensure that the siphon 7c is always filled with water and thus a trap is present, the centrifugal pump unit 2 can perform a valve test in which the flush valve 7a is briefly activated, for example, for a few seconds, in particular 3 seconds, preferably at midnight.

[0111] 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 3Flowing 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 intermediate circuit of the frequency converter in the pump electronics from becoming overloaded, the electric motor is temporarily switched off or de-energized. 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 so that the amount of water to be separated to flush the circuit, and thus the economic loss of unused drinking water, is minimized.

[0112] During separation of the water, its temperature can be measured by the pump's internal temperature sensor 20. Since fresh drinking water, usually 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 in time and switches off the flush valve 7a when the temperature reaches or falls below a target value, e.g., 20°C. In addition, the centrifugal pump unit switches off the flush 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 flush valve 7a is switched off even when the temperature of the drinking water supplied by the water supplier is above the target value.The water consumption for flushing remains minimal.

[0113] 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.

[0114] The target value, the quantity and / or the period of time are parameters that can be specified in the pump electronics. This takes into account the fact that the pump electronics cannot know at the factory how large the drinking water supply network is in which the compact unit is installed. However, the pump electronics are designed to be set up to independently determine the quantity of drinking water to be drained or the period of time for draining. This is achieved by measuring the time or the amount of water flowing through the centrifugal pump during an initial flush until the temperature has dropped to the minimum value. The then available water quantity or the time elapsed up to that point can then be saved as a parameter for a quantity-based or time-based shutdown criterion in the pump electronics 2c.

[0115] 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 determine whether the flushing valve 7a is functioning properly. If the electric motor is de-energized during this time, the proper functioning of the flushing valve can be determined by the fact that the pump speed is greater than zero because water is flowing through the pump unit 2a and driving 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 operating point or the positive pump speed is not present 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.

[0116] The additional temperature sensor 21a, located downstream of the backflow preventer 11, enables the pump electronics 2c to detect the status of the flush valve 7a at any time. This is particularly useful if the pump electronics 2c does not trigger the flush valve 7a itself. To do so, the pump electronics 2c evaluates the temperature measured by the additional temperature sensor 21a by comparing it with the temperature it measured itself. If the temperature measured by the additional temperature sensor 21a remains constant while the temperature measured by the pump-internal temperature sensor 20 drops, the flush valve 7a is obviously open and flushing is taking place (flushing mode). If, however, the two temperatures are equal, circulation is taking place (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.

[0117] An external sensor 21b is arranged in the expansion module 15 and is also connected to the pump electronics 2c via a sensor line 14. The pump electronics 2c are thus able to monitor the expansion module 15 with regard to the measured variable. If the expansion module 15 is a cooling unit, the external sensor 21b can be a temperature sensor that measures the temperature at the outlet of the cooling unit. 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, 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 a fault in the cooling unit.

[0118] 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.

[0119] Figure 4 shows another embodiment of a compact unit 1 according to the invention. It differs from the variant in Figure 3in that the centrifugal pump unit 2 is not located in front of, but behind the flushing valve 7a in the direction of flow, i.e. it is arranged on the outlet side, not on the inlet side. In other words, the flushing valve 7a is not arranged 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 does not overflow during flushing operation, i.e. it is driven like a turbine by the drinking water to be separated. This is because during flushing the water remains at rest in the intermediate line 16. Thus, there is no risk of overloading the intermediate circuit of the frequency converter. Monitoring of the flushing process is only possible to a limited extent.

[0120] For example, to use a temperature- or temperature-change-based shutdown criterion for the flush valve 7a, an additional temperature sensor 21a must be used between the inlet and the flush valve 7a. Furthermore, the centrifugal pump unit 2 cannot function as a water meter here.

[0121] An 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.

[0122] As in Figure 1As shown, in one embodiment, a temperature sensor 21c can be arranged in a line between the circuit line 31 and the consumer 32 and can measure 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. To do this, it compares the decentralized drinking water temperature with the central drinking water temperature measured by the pump-internal temperature sensor 20 and assumes poor hydraulic balancing if a deviation between the decentralized and central drinking water temperatures exceeds a limit value of, for example, 2K. If poor hydraulic balancing is detected, the centrifugal pump unit 2 outputs an error message, for example via the display 8 or the communication interface.

[0123] Figure 5shows a flow diagram for implementing a double flush. The double flush also serves to replace the water volume in the intermediate line 16 that remains in the intermediate line 16 during conventional flushing via the flush valve 7a, since this forms a branch line due to the non-return valve 11.

[0124] The method is based on circulation operation, in which the centrifugal pump unit 2 circulates the water in the circuit line 31, step S1. During circulation operation, a continuous check is carried out to determine whether a condition for flushing the circuit line exists, step S2. Such a flushing condition can be, for example, that no or only insufficient tapping activity has been detected at the consumers 32 over a certain period of time, or the temperature of the drinking water supplied reaches or exceeds the upper limit of, for example, 25°C, or the temperature of the drinking water supplied 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 time, for example, 72 hours, has passed, or a certain date and / or time has been reached, or a manual trigger command for flushing is received via the display and operating unit 2d, or a remote trigger command for flushing is received via the communication interface, in particular the web interface.

[0125] If the condition is met, the flush valve is opened in step S3 and the fresh drinking water flows through the main line 29 into the circuit line 31 or into the central flow line 33, the local flow lines 34, the local return lines 35 and the central return line 36 until it reaches the centrifugal pump unit 2 and the flush valve 7a, where it is discharged.

[0126] 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.

[0127] If the condition is met, the flush valve is closed in step S5, and the centrifugal pump unit 2 returns to circulation mode, step S6. However, this only lasts for a comparatively short period of time, for example, 60 seconds for approximately 50 meters of pipeline, 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.

[0128] The flushing valve 7a is then opened again (step S7), so that the displaced water volume in the intermediate line 16, driven by the incoming fresh water, flows to the flushing valve 7a and is separated there. Thus, a water exchange takes place in the entire circuit. During flushing, a check is again carried out to determine whether a condition for ending flushing has been met (step S8). Since the water already has its minimum temperature at the start of flushing, the predefined flushing duration or the predefined flushing volume can be used as the stop condition. Alternatively, a modified temperature change condition can be used, in which the centrifugal pump unit first evaluates the water temperature to determine whether it 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.

[0129] 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.

[0130] Figure 5shows a flowchart for implementing hot spot detection. This method is used to estimate the location of a heat source causing an unusual heat input into the drinking water supply network 30. The location is determined in the form of a distance from the centrifugal pump unit 2. Knowing the pipe lengths of the drinking water supply network 30, the distance can then be used to determine exactly where the heat source must be located in the building in which the drinking water supply network 30 extends, what the heat source is, and whether the heat input into the drinking water supply network 30 caused by the heat source can be prevented.

[0131] For hot spot detection, the centrifugal pump unit or the pump electronics, starting from circulation mode, carries out the following in sequence: Figure 6 illustrated steps: S10Switching off the pump unit 2a in order 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 circuit line, S11Restarting the pump unit 2a after a certain period of time so that the drinking water circulates again in the circuit line 31, S12Monitoring the temperature of the pumped drinking water, S13Evaluating the temperature with regard to the occurrence of a local maximum, and S14Estimating the distance of the heat source to the centrifugal pump unit from the period from the restarting of the pump unit 2a until the occurrence of the maximum and the flow rate present during this period.

[0132] For example, if the period is 20s, the distance of the heat source to the centrifugal pump unit can be determined as follows: A flow rate of 1.5 m 3 / 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 at 20s. This distance can also be specified as "hot spot after x% of the pipe volume before the circulation system".

[0133] It should be understood that the foregoing description is provided merely by way of example for illustrative purposes and in no way limits the scope of the invention. Features of the invention stated as "may," "exemplary," "preferred," "optional," "ideal," "advantageous," "optionally," or "suitable" are to be considered purely optional and do not limit the scope of protection, which is defined exclusively by the claims. To the extent that the foregoing description mentions elements, components, process steps, values, or information that have known, obvious, or foreseeable equivalents, these equivalents are encompassed by the invention.Likewise, the invention includes any changes, variations or modifications of embodiments that involve the replacement, addition, change or omission of elements, components, method steps, values ​​or information, as long as the basic idea of ​​the invention is retained, regardless of whether the change, variation or modifications lead to an improvement or deterioration of an embodiment. List of reference symbols

[0134] 1 Compact unit 2 Centrifugal pump unit 2a Pump unit 2b Electric motor 2c Pump electronics 2d Display and operating unit 3 Inlet 4 Inlet valve 5 Outlet 6 Outlet valve 7 Flushing unit 7a Flushing valve 7b Free outlet 7c Siphon 7d Valve actuating unit 7e Sensor 8 Display 9 Operating element 10 Multi-way pipe section 10a Inlet connection 10b First outlet connection 10c Second outlet connection 10d Third outlet connection 11 Backflow preventer 12 Electrical supply line 13 Control line 14 Sensor line 15 Extension 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 volume flow determination 28 house connection for drinking water 29 main line 30 drinking water supply network 31 circuit / circulation line 32 consumer 33 central flow line 34 local flow line 35 local return line 36 central return line 37 circulation valve,

Claims

1. Method for the operation and / or monitoring of water circulation in a drinking water supply network (30) having at least one circuit (31) for the circulation of drinking water, a centrifugal pump assembly (2) for drawing water from and supplying water to the circuit (31) and at least one consumer (32) supplied with drinking water from the circuit (31), in which the centrifugal pump assembly (2) has a pump unit (2a), an electric motor driving the same (2b) and pump electronics (2c) to control and regulate the electric motor (2b), characterised by the centrifugal pump assembly (2) determining operating information about water circulation or the drinking water supply network (30) and using this to monitor water circulation and to monitor - a valve within the circuit (31), and / or - a filter in the circuit (31), and / or - a control valve (37) in the circuit (31), and / or - a purge valve (7a) connected to the circuit (31) to drain drinking water from the circuit (31), and / or - a backflow preventer (11) connected in series with the centrifugal pump assembly (2), and / or - a backflow preventer (11) connected downstream from a purge valve (7a) connected to the circuit (31), and / or - a tapping activity on the consumer (32), and / or - the drinking water supply network (30) to detect - a possible structural change in the drinking water supply network (30), and / or - possible defective hydraulic balancing, and / or - the radiation of heat into the drinking water supply network from a heat source.

2. Method according to claim 1, characterised by the centrifugal pump assembly (2) determining its flow, pumping head or the temperature of the conveyed drinking water and monitoring this for a change or for reaching a limit value.

3. Method according to claim 2, characterised by the centrifugal pump assembly (2) assuming that a valve within the circuit (31) is closed when the flow falls below a lower limit value and, in particular, outputting a corresponding message.

4. Method according to one of the preceding claims, characterised by the centrifugal pump assembly (2) regularly determining its working point at intervals ranging from several hours to a few days, preferably at night, and monitoring changes in the operating point, in which the centrifugal pump assembly (2) - assumes a structural change in the drinking water supply network (30) in case of an abrupt change in the working point, and / or - assumes a clogged filter in the circuit (31) when a differential pressure that helps define the working point increases gradually or exceeds a limit value, and / or - assumes a defective control valve (37) in the circuit (31) when a differential pressure that helps define the working point decreases gradually or falls below a limit value and, in particular, the centrifugal pump assembly (2) outputs a corresponding message.

5. Method according to one of the preceding claims, characterised by the centrifugal pump assembly (2) being arranged, in the flow direction of the drinking water, upstream of a purge valve (7a) connected to the circuit (31) to drain drinking water from the circuit (31) and determining, in the de-energized state, whether its rotational speed is greater than zero, in which the centrifugal pump assembly (2) assumes that the purge valve (7a) is open if the rotational speed is greater than zero or, when purge mode is active, assumes that the purge valve (7a) is defective if the rotational speed is zero and, in particular, outputs a corresponding message.

6. Method according to one of the preceding claims, characterised by the centrifugal pump assembly (2) being arranged, in the flow direction of the drinking water, upstream of a purge valve (7a) connected to the circuit (31) to drain drinking water from the circuit (31) and determining, in the de-energized state, whether its rotational speed is greater than zero, in which the centrifugal pump assembly (2) assumes when purge mode is active that a backflow preventer (11) connected in series with the centrifugal pump assembly (2) is defective if the rotational speed is greater than zero and, in particular, outputs a corresponding message.

7. Method according to one of the preceding claims, characterised by the centrifugal pump assembly (2) determining its working point continuously or quasi-continuously and the centrifugal pump assembly (2) assuming a tapping activity on the consumer (32) if the working point changes, in which each tapping activity in particular is documented.

8. Method according to one of the preceding claims, characterised by the centrifugal pump assembly (2) controlling a purge valve (7a) connected to the circuit (31) to drain drinking water from the circuit (31).

9. Method according to claim 8, characterised by the centrifugal pump assembly (2) triggering the purge valve (7a) when - no or only insufficient tapping activity has been detected on the consumer (32) over a certain time interval, or - the temperature of the drinking water reaches or exceeds an upper limit value, or - the temperature of the drinking water is above a certain limit value for a specified time interval, or - a certain time interval has elapsed, or - a certain date and / or a certain time is reached, or - it receives a manual command to trigger purging via a display and operator panel (2d) of the centrifugal pump assembly (2), or - it receives a remote command to trigger purging via a communication interface, notably a web interface.

10. Method according to claim 8 or 9, characterised by the centrifugal pump assembly (2) closing the purge valve (7a) when - the temperature of the conveyed drinking water reaches or falls below a lower limit value, or - the temperature no longer changes or the change in temperature of the conveyed drinking water falls below a limit value, or - a predefined purge duration has elapsed, or - a predefined purge volume has been drained.

11. Method according to one of the claims 8 through 10, characterised by the centrifugal pump assembly (2) inhibiting activation of the purge valve (7a) when - sufficient tapping activity on the consumer (32) was detected over a defined time interval, or - it receives a manual suppression command from a display and operator panel (2d) of the centrifugal pump assembly (2), or - it receives a remote suppression command via a communication interface, notably a web interface.

12. Method according to one of the preceding claims, characterised by the centrifugal pump assembly (2) being connected to a least one sensor (21a, 21b, 21c), notably an additional temperature sensor, and evaluating an electrical signal of this sensor (21a, 21b, 21c).

13. Method according to one of the preceding claims, characterised by the centrifugal pump assembly (2) recording the temperature of the drinking water in the flow direction upstream of a purge valve (7a) connected to the circuit (31) and downstream of a backflow preventer (11) connected downstream of the purge valve (7a), in which the centrifugal pump assembly (2) - in case of unequal temperature values when the purge valve (7a) is closed, assumes that the purge valve (7a) is defective, and / or - in case of equal temperature values when the purge valve (7a) is open, assumes that the backflow preventer (11) is defective, and, in particular, the centrifugal pump assembly (2) outputs a corresponding message.

14. Method according to one of the preceding claims, characterised by the centrifugal pump assembly (2) comparing at least one peripheral drinking water temperature with a central drinking water temperature, in which the peripheral drinking water temperature is determined in a local ring line (34, 35) supplied by the ring line (31) in which the centrifugal pump assembly (2) conveys the drinking water and the central drinking water temperature is determined by the centrifugal pump assembly (2) or a temperature sensor (21a) connected to the same and the centrifugal pump assembly (2) assumes faulty hydraulic balancing and, in particular, outputs a corresponding message when a deviation between the peripheral and central drinking water temperature exceeds a limit value.

15. Method according to at least claim 8, characterised by the centrifugal pump assembly (2) opening the purge valve (7a) for purging, closing it, then conveying the drinking water into the circuit (31) again for a time interval, notably of a few seconds to several minutes, and then opening the purge valve (7a) again.

16. Method according to at least claim 1, characterised by the centrifugal pump assembly (2) performing the detection of a heat source when heat radiates into the drinking water supply network (30) by performing the following steps: a. Switching off the pump unit (2a) to permit, with no circulation in the ring line (31), a locally limited volume in a pipe section of the drinking water supply network (30) located adjacent to the heat source to be heated by the heat source, b. switching the pump unit (2a) back on after a certain time interval, c. monitoring the temperature of the conveyed 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 assembly (2) based on the time interval from switching the pump unit (2a) back on to the occurrence of the maximum and the existing flow in this time interval.

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