Patent Application
20240240831
This application claims priority to EP Application No. 23151591.7, filed on Jan. 13, 2023, and entitled “Method and controller to operate a domestic hot water system and domestic hot water system,” the entire contents of which are hereby incorporated by reference.
The present disclosure relates to a method to operate a domestic hot water system. Further, the present disclosure relates to a controller to operate a domestic hot water system and to a domestic hot water system.
Domestic hot water systems comprise a tank to store hot water and at least one remote location being remote from the tank. At a respective remote location water stored within the tank can be provided to a respective water consumer. The water consumer at the respective remote location can be a shower, bathtub or the like. The respective remote location is connected to the tank through a respective water pipe.
In such a domestic hot water system a microbiological growth of e.g. the legionella bacterium may occur under certain conditions. The legionella bacterium and other bacteria are found naturally in fresh water and given the right conditions the respective bacterium can contaminate the domestic hot water system. Infection occurs by directly breathing in a mist of water droplets containing the respective bacterium. There is a need for a method to operate a domestic hot water system in order to minimize the risk of an infection with bacteria like the legionella bacterium.
U.S. Pat. No. 7,870,975 B2 discloses a water dispensing appliance having a control device, wherein the control device is connected to temperature sensors. The temperature sensors can measure the water temperature at defined locations. A thermal sterilization operation may be carried out thereby killing out bacteria. Such a thermal sterilization operation may be triggered automatically following predetermined inactive periods of the water dispensing appliance or once a predetermined quantity of water has been dispensed or at predetermined time intervals.
U.S. Pat. No. 9,409,110 B2 and CN 1114 150 734 A disclose other prior art.
The brochure oventrop, Potable water, “Aquanova-System”, Distribution and hygiene of potable water, PR 246-EN/20/01.2019/MW, Overntrop GmbH & Co. KG, discloses domestic hot water systems and a thermostatic valve to provide thermal disinfection for an anti-legionella function.
Against this background a novel method to operate a domestic hot water system as defined in claim 1 and a novel controller of a domestic hot water system as defined in claim 10 as well as a novel domestic hot water system as defined in claim 12 are provided that allow to operate a domestic hot water system in order to minimize the risk of an infection with bacteria like the legionella bacterium.
The method according to claim 1 comprises the following steps: Measuring a respective temperature at a respective remote location or at the respective water pipe with the respective temperature sensor. Determining from the respective temperature measured by the respective temperature sensor a water usage event at the respective remote location. Determining during a determined water usage event a temperature profile from the temperature measured by the respective temperature sensor. Determining from the temperature profile determined during the water usage event a risk factor of microbiological growth at the respective remote location or of a microbiological growth within the respective water pipe. Initiating and executing a disinfection cycle for the respective remote location or the respective water pipe which guides the water to the respective remote location if the respective risk factor of microbiological growth is above a respective risk threshold.
The above steps allow to operate a domestic hot water system in order to minimize the risk of an infection with bacteria like the legionella bacterium. First, a water usage event is determined from the temperature measured by the respective temperature sensor. If a water usage event has been determined, then a temperature profile for the water usage event is determined. On basis of the temperature profile for the water usage event a risk factor of microbiological growth is determined. If the is above a respective risk threshold, then a disinfection cycle is initiated and executed.
Preferably, the respective water usage event is automatically determined on basis of a change rate of the respective temperature measured by the respective temperature sensor. A water usage event can be determined in an easy and reliable manner on basis of the change rate of the respective measured temperature.
Preferably, the risk factor of microbiological growth is automatically increased if, within the determined temperature profile, the measured temperature or a temperature depending on the measured temperature is above a first, lower temperature and below a second, upper temperature threshold. Further, the risk factor of microbiological growth is preferably automatically decreased if, within the determined temperature profile, the measured temperature or the temperature depending on the measured temperature is above the second, upper temperature threshold. Further, the risk factor of microbiological growth is automatically kept constant or is automatically decreased if, within the determined temperature profile, the measured temperature or the temperature depending on the measured temperature is below the first, lower temperature threshold. This allows to determine the risk factor in an easy and reliable manner.
Preferably, the disinfection cycle is automatically executed in such a manner that water having a defined disinfection water temperature is flowing from the tank through the respective water pipe towards the respective remote location for a defined disinfection time interval. This allows to kill out bacteria in an easy and reliable manner.
In addition to the features with which a risk factor of microbiological growth is determined during a detected water usage event, the method may comprise the following steps: Determining a time interval of no water usage at a respective remote location. Executing a disinfection cycle for the respective remote location or the respective water pipe if the duration of the time interval of no water usage is above a respective threshold. This allows to further minimize the risk of an infection with bacteria like the legionella bacterium.
In addition to the features with which a risk factor of microbiological growth is determined during a detected water usage event, the method may comprise the following steps: Determining from the temperature measured by at least one tank temperature sensor a risk factor of microbiological growth within the tank. Executing a disinfection cycle for the tank if the respective risk factor of microbiological growth is above a respective risk threshold. This allows to further minimize the risk of an infection with bacteria like the legionella bacterium.
Further on, a controller to operate a potable water system as defined in the claim 10 and a domestic hot water system as defined in the claim 12 having such a controller are provided.
Preferred developments are provided by the dependent claims and the description which follows. Exemplary embodiments are explained in more detail on the basis of the drawing, in which:
The domestic hot water system 10 further comprises at least one remote location 12 being remote from the tank 11. At the at least one remote location 12 water stored within the tank 11 can be provided to a respective water consumer 13. The water consumer 13 can be a shower, bathtub or the like.
The respective remote location 12 is connected to the tank 11 through a respective water pipe 14.
The tank 11 further comprises a heating unit 15 positioned at a distance from a bottom wall of the tank 11. The heating unit 15 is configured to heat the water stored within the tank 11 in such a manner that water heated by the heating unit 15 rises up within the tank 11 such that the heated water is stratified above unheated water within the tank 11.
Hot water HW can be taken out of the tank 11 through the water pipe 14 in order to provide the hot water to the respective water consumer 13. The water pipe 14 is connected to a top wall of the tank 11 or to the side wall of the same adjacent to the top wall.
The domestic hot water system 10 further comprises at least one temperature sensor 16 assigned to the respective remote location 12 or to the respective water pipe 14 guiding the water stored within the tank 11 to the respective remote location 12. The temperature sensor 16 is configured to measure the water temperature at the respective remote location 12 or at the respective water pipe 14 guiding the water to the respective remote location 12.
In
The hot water storage device 10 further comprises a controller 18. The controller 18 is configured to receive respective measurement signals from the at least one temperature sensor 16 and from the tank temperature sensor 17.
The controller 18 is further configured to control the heating unit 15 and thereby the water temperature of the water stored within the tank 11. The controller 18 provides a control signal to the heating unit 15 in order to control the operation of the heating unit 15 of the hot water storage device 10.
The water recirculated through the recirculation pipe 19 may also be guided to a drain 21 depending on the opening/closing status of a valve 22.
The present disclosure provides a method to operate such a domestic hot water system 10 allowing to operate the domestic hot water system 10 in a manner that the risk of an infection with bacteria like the legionella bacterium is minimized. The present disclosure provides further the controller 18 of the domestic hot water system 10 as well as the domestic hot water system 10.
The method according to the present disclosure comprises at least the following steps:
Measure a respective temperature at the respective remote location 12 or at the respective water pipe 14 with the respective temperature sensor 16.
Determine from the respective temperature measured by the respective temperature sensor 16 a water usage event at the respective remote location 12.
Determine during a determined water usage event a temperature profile 24 from the temperature measured by the respective temperature sensor 13.
Determine from the temperature profile 24 determined during the water usage event a risk factor of microbiological growth at the respective remote location 12 or a risk factor of microbiological growth within the respective water pipe 14.
Execute a disinfection cycle for the respective remote location 12 or the respective water pipe 14 if the respective risk factor of microbiological growth is above a respective risk threshold.
The controller 18 is configured to automatically carry out the method.
The controller 18 is configured to receive from the respective temperature sensor 16 a respective temperature measured by the respective temperature sensor 16 at a respective remote location 12 or at the respective water pipe 14.
The controller 18 is further configured to determine automatically from the respective temperature measured by the respective temperature sensor 16 a water usage event at the respective remote location 12.
The controller 18 is further configured to determine automatically during a determined water usage event a temperature profile 24 from the temperature measured by the respective temperature sensor 16.
The controller 18 is further configured to determine automatically from the temperature profile 24 determined during the water usage event a risk factor of microbiological growth at the respective remote location 12 or of microbiological growth within the respective water pipe 14.
The controller 18 is further configured to initiate and control automatically the execution of a disinfection cycle for the respective remote location 12 or the respective water pipe 14 if the respective risk factor of microbiological growth is above the respective risk threshold.
The above features allow the operation the domestic hot water system 10 with a minimized risk of an infection with bacteria like the legionella bacterium.
First, a water usage event at a respective remote location 12 is determined on basis of the temperature measured by the respective temperature sensor 16. If a water usage event has been determined at a respective remote location 12, then a temperature profile for the water usage event is determined. On basis of the temperature profile of the water usage event a risk factor of microbiological growth at the respective remote location 12 or at the respective water pipe 14 is determined. If the risk factor is above the respective risk threshold, then the disinfection cycle is initiated and executed.
The respective temperature sensor 16 measures continuously or at a defined sampling rate the temperature at the respective remote location 12 or at the respective water pipe 14. The respective temperature sensor 16 provides its measurement signal to the controller 18. The controller is configured to receive the measurement signal from the respective temperature sensor 16 through a data interface.
Preferably, the respective water usage event is automatically determined on basis of a change rate of the respective temperature measured by the respective temperature sensor 16. The controller 18, in particular a processor of the controller 18, may calculate a derivation over time of the measurement signal provided by the respective temperature sensor 16 in order to determine the change rate. As mentioned above, the measurement signal is provided by the respective temperature sensor 16 to the controller 18. Said measurement signal may be stored in a memory of the controller 18. The processor of the controller 18 may determine the change rate on basis of the measurement signal stored in the memory.
If the change rate is below a respective threshold, no water usage event is determined. If the change rate is below the respective threshold, a water usage event is determined. A water usage event may also be called water consumption event.
If a water usage event is determined, a temperature profile 24 for the respective water usage event is determined from the temperature measured by the respective temperature sensor 16.
On basis of the temperature profile 24 determined during the water usage event the risk factor of microbiological growth at the respective remote location 12 or of microbiological growth within the respective water pipe 14 is determined.
The risk factor of microbiological growth is automatically increased by the controller 18 if, within the determined temperature 24 profile, the measured temperature T or a temperature depending on the measured temperature T is above a first, lower temperature L1 and below a second, upper temperature threshold L2.
Further, the risk factor of microbiological growth is automatically decreased by the controller 18 if, within the determined temperature profile 24, the measured temperature T or the temperature depending on the measured temperature T is above the second, upper temperature threshold L2.
If the measured temperature T or the temperature depending on the measured temperature T is above the second, upper temperature threshold L2 for a defined time interval, the risk factor may be reset or initialized to a value of sterilized water system 10 be either thermally or chemically sterilized.
Further, the risk factor of microbiological growth is automatically kept constant or may alternatively be automatically decreased by the controller 18 if, within the determined temperature profile 24, the measured temperature T or the temperature depending on the measured temperature T is below the first, lower temperature threshold L1.
The risk factor of microbiological growth may be kept constant if the temperature T measured during a water usage event is below the first, lower temperature threshold L1 for a time interval being smaller that a respective time interval.
The risk factor of microbiological growth may be kept decreased if the temperature T measured during a water usage event is below the first, lower temperature threshold L1 for a time interval being larger that the respective time interval.
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Instead of the measured temperature T, a temperature depending on the measured temperature T may be used to determine the risk factor of microbiological growth. A moving average temperature of the measured temperature may be determined by the controller 18 and the risk factor of microbiological growth may be determined by the controller 18 on basis of the moving average temperature.
A disinfection cycle is automatically initiated and executed if the determined risk factor of microbiological growth is above a respective threshold. The disinfection cycle is automatically initiated and executed in such a manner that water having a defined disinfection water temperature is flowing from the tank 11 through the respective water pipe 14 towards the respective remote location 12 for a defined disinfection time interval.
For the disinfection cycle at least a portion of the water stored within the tank 11 is automatically heated by the heater 15 to the defined disinfection water temperature if the respective risk factor is above the respective risk threshold and if the temperature of the water stored within the tank 11 is below said disinfection water temperature. During a disinfection cycle the hot water may be guided through the recirculation pipe 19 to the drain 21 or to the water tank 11. If the hot water is guided to the tank 11, the water within the tank 11 will be de-stratified.
In addition, a time interval of no water usage at a respective remote location 12 may be determined by the controller 18 on basis of the signal provided by the respective temperature sensor 16. A disinfection cycle for the respective remote location 12 or the respective water pipe 14 may be executed if the duration of the time interval of no water usage is above a respective threshold.
In addition, a risk factor of microbiological growth within the tank 11 may be determined from the temperature measured by the at least one tank temperature sensor 17. A disinfection cycle for the tank 11 may be initiated and executed if the respective risk factor of microbiological growth is above a respective risk threshold. For an disinfection of the tank 11 the entire water within the tank is heated to a temperature above a respective threshold, and the water within the tank 11 will be de-stratified.
The disclosure is directed to the method and controller 18 as well as to the domestic hot water system 10 comprising the controller 18.
| Number | Date | Country | Kind |
|---|---|---|---|
| 23151591.7 | Jan 2023 | EP | regional |
