Method for operating a pump

Abstract

A dishwasher pump has an integrated heating element, a pump chamber with an inlet and an outlet, a pump rotor within the pump chamber, and a drive motor, wherein the heating element and a temperature sensor are provided on a wall of the pump chamber. To measure calcification of the pump chamber, the pump chamber is filled with water, and then the pump rotor is rotated to mix the water in the pump chamber without delivering the water out of the pump chamber. The water temperature within the pump chamber is measured as a starting temperature with the temperature sensor, and then the heating element is activated to heat the water within the pump chamber while the water temperature within the pump chamber is measured. Then, the heating element is deactivated, and the highest temperature of the water during or immediately after the heating duration is determined. A temperature relationship between the highest temperature of the water and the starting temperature is calculated. These steps are performed in the pump at the beginning of operation after a new dishwasher installation to determine an initial temperature relationship. These steps are performed again, preferably automatically, at a later stage to determine a later temperature relationship to determine a heating efficiency of the pump by comparing the later temperature relationship and the initial temperature relationship.

Description

Technical Field

[0001] The present invention relates to a method for operating a pump having an integrated heating element and a pump suitable for performing the method together with a control device. Background Technology

[0002] Pumps for simultaneously pumping and heating water are known in the art, for example, from CN 103511349A1. They are provided with a pump chamber in which a heating element is disposed on the circumferential wall of the pump chamber. This heating element allows for very efficient heating of the water during pumping operations. One problem also addressed in EP 2772563A1 is that calcification may occur in a reinforced manner due to the high temperature inside the wall of the pump chamber where the heating element is located. This calcification is considered negative because it affects the heating efficiency of the heating element, as heating energy does not enter the water as effectively as if calcification were not present.

[0003] A method for detecting severe calcification on a heating element is known from CN 106993995A1, which utilizes various temperature sensors, primarily temperature sensors covering a large surface area of ​​the heating element. However, a drawback of this method is that it only works when dangerously high temperatures can be measured. Summary of the Invention

[0004] The object of the present invention is to provide a method for operating a pump having an integrated heating element, and particularly for determining the heating efficiency of the pump or the heating element separately by measuring the temperature.

[0005] The pump of the present invention comprises at least a pump chamber having an inlet for entering the pump chamber and an outlet for exiting the pump chamber, and a pump rotor, preferably an impeller, inside the pump chamber. The drive motor for the pump rotor is arranged in a conventional manner. Furthermore, a heating element is provided on at least a portion of the wall of the pump chamber, preferably on a circumferential sidewall of the pump chamber extending about the longitudinal axis of the pump chamber and about the rotation axis of the pump rotor. The heating element preferably has a conventional arrangement in the art, more preferably a thick-film heating element. Additionally, a temperature sensor is provided for sensing the temperature of the water in the pump chamber, the temperature sensor preferably arranged on the wall of the pump chamber, particularly on the same wall as the heating element. The temperature sensor may have a distance of 2 mm to 1 cm or even 3 cm from the heating element. The temperature sensor may advantageously be positioned on the wall of the pump chamber at a location where, even if only a small amount of water is supplied in the pump chamber, the water is in contact with the inner side of the pump chamber wall, which is directly opposite the temperature sensor mounted on the outer side of the wall.

[0006] The method of the present invention includes the following steps. In step A, water is supplied to the pump chamber. Preferably, this can be a predetermined amount of water, for example, such that the pump chamber is completely filled, and even more water may be brought in, wherein the water is partially conveyed or pumped out of the pump chamber. In step B, the pump rotor is rotated or the pump is operated, respectively, to mix or move the water throughout the pump chamber. This is done in a manner in which water is not substantially conveyed out of the pump chamber, particularly not as a permanent flow through the pump. This means that the pump can generate a specific water pressure at the outlet of the pump chamber, which reaches an equilibrium in the fluid pipe connected to the outlet, such that, for example, after at least 1 to 10 seconds, no more water is pumped out of the pump chamber. The water present in the pump chamber then remains in the pump chamber, although it is mixed or rotated by the pump rotor.

[0007] In the next step C, the temperature of the water in the pump chamber is measured using a temperature sensor. This temperature is the initial temperature and can be stored by a control device connected to the pump and the temperature sensor.

[0008] In step D, following step C, after the initial temperature has been measured, the heating element is activated to heat the water in the pump chamber. Preferably, the heating element is activated for a predetermined heating duration, which can be between 1 second and 60 seconds, preferably between 20 seconds and 30 seconds. By mixing or rotating the water in the pump chamber, uniform heating of the water is provided, such that the water temperature is directly related to the heat energy dissipated into the water from the heating element at a given heating efficiency. In the following step E, the temperature of the water in the pump chamber is again measured using a temperature sensor. This preferably occurs when the heating element is activated, more preferably permanently or continuously as long as the heating element is activated, and advantageously even for a longer period of time.

[0009] In the next step F, the heating element is preferably deactivated after the predetermined heating duration has elapsed. Preferably, the highest water temperature during or shortly after the heating duration is determined again in the control device of the aforementioned temperature sensor. In most cases, this highest water temperature in the pump chamber will be reached a few seconds after the heating duration ends, for example, 2 to 5 seconds later, or even slightly longer, for example, up to 10 seconds, in the case of a heating element with a larger heat capacity due to thicker material.

[0010] In the next step G, the temperature relationship between the highest water temperature and the initial water temperature is calculated. This temperature relationship can be of various types, such as a quotient. Preferably, the temperature relationship is a difference, such that the initial water temperature is subtracted from the highest water temperature, which typically exceeds the initial temperature. After the device with the pump has been installed and connected to a power source, for example as a start-up operation, steps A to G are performed in the pump at the beginning of operation or at the latest during one of the first 50, preferably the first 15, operating cycles. This means that the method is first performed when the pump is relatively new and may not have calcification to have an initial temperature relationship. This initial temperature relationship is preferably stored in the previously mentioned control device. It corresponds to the behavior or heating efficiency of the pump and its heating element in a state where calcification may not be present, and therefore the heating efficiency should be at its maximum.

[0011] Steps A through G are performed again in a later stage, preferably automatically, to determine the later temperature relationship to determine the heating efficiency or calcification of the pump or heating element, respectively. More specifically, this later stage may be performed after a certain number of operating cycles or operating durations of the heating pump or its heating element. For example, the later stage for performing steps A through G may be after 5 to 100 operating cycles of the pump, preferably after 10 to 50 operating cycles, where such operating cycles may correspond to the entire washing process in a dishwasher. Alternatively, the steps may be performed 30 minutes to 20 hours after the total heating operation of the heating element. This determination using the operating duration of the heating element is considered a better approach. The heating efficiency or calcification of the pump or heating element is then determined by comparing the later temperature relationship with the initial temperature relationship. Depending on the nature of the temperature relationship, the direction in which calcification on the pump chamber wall will begin and increase will change, thus a decrease in heating efficiency is expected. As mentioned earlier regarding the temperature difference, due to increased calcification causing less heat to be carried into the water in the pump chamber for a given or predetermined heating duration, the temperature difference will later be less than the initial temperature difference. This means that the highest temperature achievable during the heating duration will be lower in later stages than at the initial start of pump operation.

[0012] As explained earlier, the heating efficiency obtained from this method may not necessarily be precisely quantified. What is sufficient is that it is qualified so that it can be monitored in some way, and certain steps are implemented if the heating efficiency decreases significantly or substantially. These steps will be described below.

[0013] In one embodiment of the invention, monitoring of heating efficiency is used to take countermeasures against any substantial calcification detected in the pump chamber. It is possible that decalcification should begin when, as a specific embodiment of the temperature relationship, the later temperature difference mentioned above is less than 90% of the initial temperature difference, preferably less than 70% of the initial temperature difference. This can be achieved by generating optical and / or acoustic signals that prompt the user of the pump or the user of the household appliance with the pump to begin the pump's decalcification process. This can be done in a known manner by adding a decalcification medium to the pump's water circulation, the decalcification medium being, for example, in tablet or liquid form. Alternatively, an automatic decalcification process is started for the pump or household appliance, respectively, such that the decalcification medium automatically enters the pump's water circulation. It can be provided that, immediately after the decalcification process is completed, a method with steps A to G is performed to check whether decalcification has been successful, since at this point the heating efficiency again corresponds to the initial heating efficiency, such that the actual temperature difference is approximately the same as the initial temperature difference.

[0014] If the temperature relationship is not realized as the temperature difference explained earlier, but rather as, for example, the quotient of the highest temperature divided by the initial temperature, then this quotient will also decrease as calcification of the pump chamber wall increases. Alternatively, in this case, if the temperature quotient is less than 90% or less than 70% of the initial temperature quotient, the same steps described earlier for initiating decalcification are initiated.

[0015] As previously described, although the pump rotor should rotate to mix the water in the pump chamber so that heat is evenly distributed, water should not be pumped through the pump chamber to heat a predetermined amount of water. This can be achieved by measuring the flow through the pump, which, if such a measurement is provided, should of course be zero during the activation of the heating element. The drive motor is then adjusted to avoid this flow. Alternatively, since the details of integrating the pump into a household appliance are not always the same, and measuring the flow through the pump can be difficult, a fixed rotational speed can be predetermined for the pump. This fixed rotational speed is preferably less than 500 rpm, more preferably from 10 rpm to 300 rpm. It can be a specific fraction of the pump's rated rotational speed during normal operation, for example, 3% to 10%.

[0016] Another advantage of the invention is that, by individually determining the initial temperature relationship of the pump, the individual characteristics of the pump are automatically taken into account for later use. This preferably includes a predetermined fixed rotational speed of the pump rotor, which, when the heating element is operated at this predetermined fixed rotational speed for later use, results in a constant predetermined amount of water being drawn into or supplied to the pump chamber. Therefore, this predetermined fixed rotational speed and the constant predetermined amount of water are stored as information.

[0017] In another preferred embodiment of the invention, if steps A to G are repeated at least two or three times consecutively to find an intermediate temperature relationship from each determined temperature relationship, the temperature relationship can be determined more accurately or in a better manner. This reduces the risk that unexpected characteristics may lead to incorrect or abnormal temperature relationships. Advantageously, after each cycle of performing steps A to G, some time can be allowed to elapse to allow the pump and heating element to cool down again after the heating operation, respectively. This waiting time can be reduced by pumping some fresh and cold water. It can even be provided that the subsequent determination of heating efficiency and temperature relationship, at least separately, is integrated into the process performed by the household appliance during its normal operation, such as in a dishwasher during the rinsing process. Alternatively, the determination of temperature relationship may also be performed separately from and apart from the normal process of the household appliance, for example, after such normal process has been completed.

[0018] The predetermined heating duration can be selected between 10 seconds and 60 seconds, preferably between 20 seconds and 30 or 40 seconds. This predetermined heating duration should be advantageously selected such that the temperature difference between the activation and deactivation of the heating element should be approximately 20°C and greater, particularly up to 50°C or 60°C. It is preferable to avoid the water in the pump chamber reaching boiling temperatures greater than 90°C or 95°C. This is because at such relatively high temperatures, the effect of transferring heat energy from the heating element into the water is greatly slowed down, resulting in no linear correlation between heat energy and temperature, and in particular, no specific correlation exists at all.

[0019] What can be provided is the ability to monitor the operating voltage of the heating element and to adapt a correction factor to variations in the operating voltage, which is taken into account when determining temperature relationships. This provides an advantageous option independent of variations in the operating voltage between temperature measurements. This can be provided to accommodate variations of a few volts in the operating voltage, and to operate the pump and its heating element at 230V in Europe or 120V in the United States.

[0020] The drive voltage in the drive circuit of the drive motor can correspond to the operating voltage of the heating element, making it possible to measure only the drive voltage, which may be easier for the control unit. Preferably, the drive motor and heating element are operated with a power supply voltage, which the household appliance equipped with the pump is connected to, particularly 230V or 120V as mentioned earlier.

[0021] In another preferred embodiment of the invention, the heating element may have PTC characteristics, or may be a PTC heating element wherein its resistive behavior exhibits the PTC effect. This can provide enhanced safety of the heating element in cases where serious overheating problems may occur. On the other hand, the temperature sensor may preferably be an NTC temperature sensor having the NTC effect in its resistive behavior. This allows for accurate temperature measurement.

[0022] The pump can be structured such that it has an axial inlet into the pump chamber, making it a radial pump. The outlet exiting the pump chamber is located on the side, possibly parallel to the radial direction, such that the pump rotor is an impeller with an axial flow of water entering the impeller and a radial output of water. In normal operation, water may circulate two to five times within the pump chamber before exiting through the outlet; however, in this invention, no water should leave the pump chamber during temperature measurement.

[0023] The household appliance equipped with this pump also includes a control unit for controlling the heating element and drive motor, and for measuring temperature using a temperature sensor. It also includes a timer function to monitor the predetermined heating duration and determine when steps A through G should be executed and how many times they should be executed consecutively to determine the heating efficiency of the pump and its heating element. The control unit should have a microcontroller and, preferably, memory integrated into the microcontroller.

[0024] These and other features are available from the specification and drawings, wherein individual features can be implemented, in each case, either by themselves or in sub-combinations, in embodiments of the invention and in other fields, and can constitute the advantageous and independently patentable variations claimed herein. The subdivision of this application into separate sections and intermediate headings does not limit the general validity of the statements made under those sections and intermediate headings. Attached Figure Description

[0025] Exemplary embodiments of the present invention are schematically illustrated in the accompanying drawings and will be explained in more detail below. In the drawings:

[0026] Figure 1 A schematic diagram of a dishwasher in which the method according to the invention is implemented by a control unit is shown.

[0027] Figure 2 It shows Figure 1 A schematic diagram of the pump in a dishwasher.

[0028] Figure 3 A graph showing the temperature changing over time is shown. Figure 2 The temperature sensor on the pump has measured the temperature, and

[0029] Figure 4The drive voltage of the motor is shown to be temporarily reduced due to the activation of the heating element. Detailed Implementation

[0030] exist Figure 1 The image illustrates, schematically, a dishwasher for performing the method according to the invention. The dishwasher 11 has a washing chamber 12, which is accessible via a door 13, and is essentially as is known in the art. In the washing chamber 12, for example, two baskets 14 are arranged one above the other for holding dishes to be washed. Above the upper basket 14, a schematic spray arm 16 is provided, which rotates and has a plurality of small spray nozzles on its downward side pointing towards the basket 14. Water is pumped to the spray arm 16 via a delivery pipe 17. Preferably, more than one spray arm is provided in the washing chamber 12; however, for ease of understanding, this has been omitted. Figure 1 The aforementioned jet arm.

[0031] A so-called storage tank 19 is provided at the bottom of the cleaning chamber 12, and a drain pipe 20 guides water from this storage tank to a pump 22 according to the invention. Figure 2 Pump 22 is shown in more detail and referenced in the image. Figure 2 Describe pump 22.

[0032] The dishwasher 11 is provided with a control unit 15, which is connected to the pump 22, such as Figure 1 As shown in the diagram. This representation of the connection is illustrative and, of course, quite different in practice. From Figure 1 Clearly, pump 22 is a so-called motor heat pump used to pump water while heating it, which enables water to circulate from cleaning chamber 12 through storage tank 19 and discharge pipe 20 through delivery pipe 17 and spray arm 16 back into cleaning chamber.

[0033] Figure 2 A schematic diagram of pump 22 is shown in more detail. See CN 103511349A1 for further details. Pump 22 has a pump housing 23 in which a preferably circular pump chamber 24 is disposed. Pump chamber 24 has an external lateral pump chamber wall 25. An inlet 26 connected to a discharge pipe 20 enters the pump housing 23 and the pump chamber 24. An outlet 27 connected to a delivery pipe 17 exits from the pump chamber 24.

[0034] Within the pump chamber 24, a pump rotor 30 is disposed, which rotates when driven by a drive motor 32. The rotating pump rotor 30 rotates at approximately 3,000 to 6,000 rpm, drawing in water axially through inlet 26. This water is then jetted radially, causing it to circulate several times within the pump chamber 24 around the pump rotor 30 until it exits the pump chamber 24 via outlet 27. This is well known in the art.

[0035] The drive motors 32 are powered by the drive circuit 33 or supplied with electricity. The drive circuit 33 is connected to the drive voltage U. d The drive circuit 33 is preferably connected to a power supply voltage. The drive circuit 33 is connected to or controlled by the control unit 15. This allows control of the power of the drive motor 32, and in particular the speed of the drive motor 32, and thus the power and speed of the pump rotor 30. The drive voltage U in the drive circuit 33 can also be measured, and preferably is measured. d This information is then provided to the control unit 15.

[0036] A heating element 35 is disposed on the outer side of the pump chamber wall 25. This is known in the art and can be obtained from, for example, CN103511349A1. The heating element 35 can be configured as a thick-film heating element, or alternatively as an electric heating element in different implementations. The heating element 35 is provided with a heating element connector 36. It is connected to a switching circuit (not shown here) to utilize a drive voltage U. d The heating element 35 is operated. In a preferred embodiment of the invention, the heating element 35 is operated in a pulse mode or a pulse width modulation mode, meaning that the heating element 35 is either driven by a driving voltage U. d Full power supply or shutdown.

[0037] Heating element 35 has a PTC characteristic in its resistance. This means that as the temperature increases, the resistance of the heating element increases. This causes the temperature of heating element 35 to be higher than the expected operating temperature, which, via the PTC effect of its resistance, results in higher resistance and lower heating power output. This lower or reduced heating power output results in the water's peak temperature being lower than the maximum temperature after the heating duration if the heat generated by heating element 35 can be better transferred to the water in pump chamber 25 without calcifying on the inner side of pump chamber wall 25.

[0038] In other words, the strong calcification inside the pump chamber wall 25 negatively impacts heat transfer from the heating element 35 through the pump chamber wall 25 to the water, resulting in lower heat transfer. This leads to a higher temperature for the heating element 35, which, due to the PTC effect, results in higher resistance. Given a fixed operating voltage, this higher resistance again leads to a lower heating power output. This, along with the reduced heat transfer to the water, results in a lower maximum water temperature after the same time or heating duration. This calcification 28 in… Figure 2 The image is shown, although the thickness is greatly exaggerated here. In reality, such calcification can have a thickness between 100µm and 1mm, or even greater than 1mm.

[0039] A temperature sensor 39 is preferably disposed on the outer side of the pump chamber wall 25 at a small distance from the heating element 35. The temperature sensor 39 is disposed on the pump chamber wall 25 with good thermal conductivity to accurately measure its temperature. Essentially, the temperature sensor 39 is configured to measure the temperature of the water inside the pump chamber 24 and the temperature on the inner side of the pump chamber wall 25. The temperature sensor 39 is an NTC temperature sensor. It has a sensor connector 40, which is preferably connected to the control unit 15. Additional temperature sensors, such as the temperature sensor 39, may be disposed on the pump chamber 24 or the pump chamber wall 25, respectively.

[0040] In the method according to the invention, the basic operation for measuring temperature is to operate the pump rotor 30 at low power and low speed, for example, 300 rpm. This can be about 5% to 10% of the maximum speed. This relatively low speed of the pump rotor 30 allows some water to be drawn into the pump chamber 24 via the discharge pipe 20 and the inlet 26. The pump rotor 30 makes a slight attempt to pump or transport water via the outlet 27 and the delivery pipe 17. Due to the low rotational speed of the pump rotor 30, the water cannot be transported much higher than the outlet 27, for example, only 3 cm to 5 cm in the vertical direction. Then, an equilibrium is established, which is important in itself. This equilibrium is used to ensure that some water is in the pump chamber 24, preferably mostly or completely filled, wherein the amount of water does not change and neither flows out of the pump chamber 24 through the outlet 27 nor flows through the inlet 26. The water in the pump chamber 24 is also well mixed by the rotating pump rotor 30.

[0041] Temperature sensor 39 measures the temperature of the water circulating in pump chamber 24, particularly the temperature of cold water at 24°C. This information is provided to control unit 15. If this information is present in control unit 15, heating element 35 is activated, preferably via PWM at its maximum power due to its preferred operation. This heating process can be initiated from... Figure 3 As can be seen, the thick line represents the temperature T as a function of time t. At 56 seconds after startup, the heating element 35 is activated at full power. The water in the pump chamber 24 is mixed and thus able to absorb the heat generated by the heating element 35 in an optimal manner. The temperature sensor 39 is able to sense the temperature according to... Figure 3 The temperature rises as indicated by the thicker line in the image. After a heating time of 26 seconds, the heating element 35 is turned off again. A few seconds later, the measured temperature has reached its maximum value of 61°C. After reaching this maximum value, the temperature drops again.

[0042] Since the initial temperature of the cold water in pump chamber 24 has been measured to be equal to 24°C before heating element 35 is activated, the temperature difference is 37°C or 37K. This temperature difference is a very simple implementation of the temperature relationship mentioned earlier. The value of 37K is stored in control unit 15 as the initial temperature difference. This measurement process can be repeated once or twice to find an intermediate initial temperature difference that does not depend on chance.

[0043] If, after several operating cycles of pump 11, some calcification 28 has already formed on the inner side of pump chamber wall 25, and if temperature measurement is then resumed, then the temperature T will progress over time. Figure 3 The above is shown in thin lines. Due to the effects described above, not only is less heat energy carried into the water in the pump chamber 24 via the heating element 35 through the pump chamber wall 25, but calcification also results in the heating element 35 itself heating more effectively than in the case without calcification 28 described above. This again leads to a reduction in the heating power of the heating element 35 due to its PTC characteristics. This results in a reduction in the maximum power achieved with either the heating element 35 or the pump 22, and after a heating time of 26 seconds, only a maximum temperature of 57°C is reached. After several operating cycles of the pump 11, this later temperature difference is therefore only 33°C. Furthermore, due to the reduced thermal conductivity caused by the increased calcification 28, this maximum temperature is reached even later than in the initial case described above.

[0044] Therefore, the initial temperature difference is already 37°C, and later the temperature difference is 33°C. If the difference between these two is now, for example, 5°C, this is a clear indication to the control unit 15 that calcification 28 is present in the pump chamber 24, and therefore the heating efficiency of the pump 22 has been reduced too much. If the temperature difference is too large, a signal can be sent to the user to start the decalcification process, for example by adding some substance to the dishwasher 11 to initiate decalcification, as is known in the art.

[0045] Even according to Figure 3 The maximum temperature should not be reached only after the heating element 35 has been deactivated again; the temperature at the end of the heating duration can be measured immediately and compared with each other.

[0046] In another variation of this embodiment, it can be configured to provide not only one temperature sensor 39 at the pump chamber 24, but also two or even three temperature sensors. Therefore, notification regarding the measurement of the difference can be made for only one or all of them.

[0047] As previously described, the preferred method is to measure the drive voltage U at drive circuit 33. d It is also the operating voltage of the heating element 35. If the driving voltage U is when the heating element 35 is switched on...d If the voltage is slightly reduced, this information can be used to correct the driving voltage U supplied to the heating element 35. d The value of. This is in Figure 4 As shown in the image.

[0048] As previously described, this measurement can be repeated several times, for example, three times, to find the median. Then, by operating pump 22 at its rated power, the water that has been heated to the specified temperature... Figure 3 The water at the specified temperature is removed from pump chamber 24. Then, as previously described, fresh and cold water can be drawn in, and their temperatures can be measured again to have the correct starting point for the temperature difference.

[0049] Figure 4 The driving voltage of the drive motor 32 is shown, which has the characteristic due to its relationship with... Figure 3 The temporary voltage reduction caused by activating the heating element 35 within the same time frame. This reduction is approximately 5V. As previously described, this reduction can be mathematically eliminated due to the driving voltage U. d It is also used to power the heating element 35, so the heating power is also affected by this reduction. However, the control unit 15 can observe the drive voltage U due to its connection with the drive circuit. d Therefore, compensation for this is easy for the control unit 15. The control unit 15 and the drive circuit 33 can even be implemented in a single housing or in a common component.

Claims

1. A method for operating a pump having an integrated heating element, wherein the pump comprises: - A pump chamber having an inlet for entering the pump chamber, an outlet for exiting the pump chamber, and walls. -The pump rotor inside the pump chamber, - The drive motor for the pump rotor, - Heating elements disposed on at least a portion of the wall of the pump chamber, and - A temperature sensor for sensing the temperature of the water in the pump chamber. The method comprises the following steps: A. Water is supplied to the pump chamber. B. Rotate the pump rotor to mix the water in the pump chamber without expelling the water from the pump chamber. C. The temperature of the water in the pump chamber is measured using the temperature sensor, and this temperature is used as the starting temperature. D. After measuring the temperature of the water, activate the heating element to heat the water in the pump chamber. E. The temperature of the water in the pump chamber is measured using the temperature sensor. F. During the heating duration of step D or within a maximum of 10 seconds after the heating duration of step D, deactivate the heating element and determine the highest temperature of the water. G. Calculate the temperature relationship between the highest temperature and the initial temperature of the water. Specifically, steps A through G are performed in the pump at the start of pump operation or during one of the first 50 operating cycles of the pump to determine the initial temperature relationship. Specifically, steps A through G are performed again at a later stage to determine the later temperature relationship, thereby determining the pump's heating efficiency by comparing the later temperature relationship with the initial temperature relationship. The water in the pump chamber is heated to a maximum temperature not exceeding 80°C.

2. The method according to claim 1, wherein, In step A, a predetermined amount of water is provided in the pump chamber.

3. The method according to claim 1, wherein, In step D, after the temperature of the water is measured, the heating element used to heat the water in the pump chamber is activated for a predetermined heating duration.

4. The method according to claim 3, wherein, After the predetermined heating duration in step D, the heating element is deactivated in step F.

5. The method according to claim 1, wherein, The temperature relationship is such that the temperature difference between the highest temperature of the water and the initial temperature of the water is subtracted from the highest temperature of the water, wherein if the initial temperature difference is greater than the subsequent temperature difference, it is determined that the heating efficiency of the pump is reduced.

6. The method according to claim 5, wherein, If the subsequent temperature difference is less than 90% of the initial temperature difference, a signal is generated to prompt the user to start the decalcification process of the pump, or the automatic decalcification process of the pump is started.

7. The method according to claim 6, wherein, In step B, the rotational speed of the pump rotor is less than 500 rpm.

8. The method according to claim 7, wherein, In step B, the rotational speed of the pump rotor is from 10 rpm to 300 rpm.

9. The method according to claim 1, wherein, When the later temperature relationship is compared with the initial temperature relationship, it is determined that the heating efficiency is reduced if the initial temperature relationship is different from the later temperature relationship.

10. The method according to claim 1, wherein, Repeat steps A through G at least two or three times consecutively to find the median temperature relationship from each determined temperature relationship.

11. The method according to claim 1, wherein, Repeat the method as described in a rule.

12. The method according to claim 11, wherein, The method is repeated in a regular manner by multiple operating cycles of the electrical equipment equipped with the pump, wherein the number of operating cycles between each regular repetition is between 5 and 100.

13. The method according to claim 3, wherein, The predetermined heating duration is between 10 seconds and 60 seconds.

14. The method according to claim 13, wherein, The predetermined heating duration is between 20 and 30 seconds.

15. The method according to claim 1, wherein, The operating voltage of the heating element is monitored, and a correction factor is adapted to changes in the operating voltage, wherein the correction factor is considered when determining the temperature relationship.

16. The method according to claim 15, wherein, When determining the temperature relationship, the correction factor is taken into account such that the temperature relationship is independent of the operating voltage or its variation.

17. The method according to claim 15, wherein, The drive voltage in the drive circuit for the drive motor corresponds to the operating voltage of the heating element, and the drive voltage is measured.

18. The method according to claim 1, wherein, The heating element is a PTC heating element exhibiting the PTC effect with resistive behavior.

19. The method according to claim 1, wherein, The temperature sensor is an NTC temperature sensor exhibiting the NTC effect with resistive behavior.

20. The method according to claim 1, wherein, The pump is provided with an axial inlet for entering the pump chamber.

21. The method according to claim 20, wherein, The outlet exiting the pump chamber is on the side or in a radial direction parallel to the pump chamber.

22. The method according to claim 1, wherein, The water in the pump chamber is heated to a maximum temperature not exceeding 65°C.

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