Arrangement for Heating a Liquid

Abstract

The invention relates to an arrangement for heating a liquid. An energy unit (1) supplies a heat exchanger (2) with thermal energy. The heat exchanger (2) transfers the thermal energy to the liquid which is received by a container (3). The container (3) has an opening (21). A pump (20) is connected to the opening (21) of the container (3) and to the heat exchanger (2) so as to deliver liquid from the opening (21) and/or from the heat exchanger (2).

Claims

1-8. (canceled)

9. An arrangement for heating a liquid, comprising: an energy unit; a heat exchanger; a container; and a pump, wherein the energy unit is configured to supply the heat exchanger with thermal energy, wherein the heat exchanger is configured to transfer the thermal energy to the liquid, wherein the container is configured to receive the liquid, wherein the container has an opening, wherein the pump is connected to the opening of the container and to the heat exchanger, wherein the pump is configured to deliver liquid from the opening and/or from the heat exchanger.

10. The arrangement of claim 9, further comprising: an additional pump configured to deliver the liquid to be heated through the heat exchanger, wherein the opening of the container is arranged between the heat exchanger and the pump.

11. The arrangement of claim 10, further comprising: a temperature sensor configured to measure a temperature of the liquid heated by the heat exchanger; and a control device configured to receive measured values of the temperature sensor and use the measured values for controlling the additional pump.

12. The arrangement of claim 10, further comprising: an aeration/ventilation valve configured to allow air to be discharged from the arrangement; and a ventilation pump configured to discharge air and liquid through a return line, wherein the return line opens upstream of the aeration/ventilation valve and upstream of the additional pump.

13. The arrangement of claim 12, further comprising: a component located between the aeration/ventilation valve and the ventilation pump, wherein the component is configured to open when a predetermined pressure difference is exceeded such that the liquid can flow in a direction of the ventilation pump.

14. The arrangement of claim 12, wherein the additional pump is configured to deliver air through the heat exchanger in one delivery direction and deliver liquid through the heat exchanger in another delivery direction.

15. The arrangement of claim 12, further comprising: a descaling device arranged along the return line and configured to add a descaling agent to the liquid delivered by the ventilation pump.

16. The arrangement of claim 9, further comprising: a mixing section; a cold water path open onto the mixing section; a mixed temperature sensor configured to measure a temperature of the liquid in the mixing section; and a control device configured to control the pump and/or a cold water path pump for delivering the liquid in the cold water path based on measured values of the mixed temperature sensor and a predetermined temperature range, wherein the pump is configured to deliver heated liquid to the mixing section.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0077] More specifically, there are numerous possibilities for designing and further developing the arrangement according to the invention. For this purpose, reference is made, on the one hand, to the claims which depend on claim 1, and, on the other hand, to the description below of example embodiments in conjunction with the drawing, in which:

[0078] FIG. 1 shows a basic representation of a device for heating a liquid,

[0079] FIG. 2 shows an embodiment of the components of a system for delivering heated water,

[0080] FIG. 3 shows the embodiment of FIG. 2 without reference numerals, but with the indication of functional blocks,

[0081] FIG. 4 shows an alternative embodiment of part of the system of FIG. 2,

[0082] FIG. 5 shows a further embodiment of a system according to a second teaching,

[0083] FIG. 6 shows an additional embodiment of the area around the container,

[0084] FIG. 7 shows a detailed view of an alternative arrangement of FIG. 2, and

[0085] FIG. 8 shows a detailed view of a further alternative arrangement of FIG. 2.

DETAILED DESCRIPTION

[0086] FIG. 1 schematically shows the basic structure of a device for heating at least one liquid. In one variant, the device also heats air. Therefore, the device generally serves to heat fluids. As the liquid is respectively water in the described illustrations, only water is referred to in the following. As shown below, the device can be connected to other components of a periphery to generally form an arrangement (or a system) for heating fluids. The arrangement is for example arranged in a caravan, a mobile home or on a boat. Therefore, the arrangement is preferably arranged in or relative to a movable interior space.

[0087] The thermal energy for heating is generated by the energy unit 1 by the combustion of a fuel-air mixture and/or by electrical energy, and is transferred to the liquid by the heat exchanger 2. For this purpose, a cold water pump 11 pumps the cold water to be heatedfor example from a fresh water tank of a vehicle or another cold water tankthrough the heat exchanger 2. The heated water is introduced into a warm water container 3 and flows from there to a fitting 5. The arrangement of the inflow and outflow paths is here purely exemplary.

[0088] Cold water is also fed to the fitting 5 through a cold water path 4, a cold water path pump 12 being provided. In one embodiment, the cold water originates from the aforementioned cold water tank. In the embodiment shown, the heated water and the cold water are mixed in a mixing section 30, so that water tempered at a desired temperature reaches the fitting 5.

[0089] Furthermore, a control device 6 is provided for the processes in the device, which acts on components of the device or the system described below based on measured values, for example. In one variant, the control device 6 controls the energy unit 1 and thus also the heat exchanger 2 or the heating process. In one variant, this is realized in a time-controlled manner. Alternatively or additionally, the heating operation is started by a user. In one embodimentnot shownthe user initiates the start via a switch or an app functionality, for example.

[0090] FIG. 2 shows a system which provides heated service water at the fitting 5. The system can also be referred to as arrangement. Though the illustrated system corresponds to the first teaching of the invention, large parts of the description also apply to the system according to the second teaching.

[0091] The system is described below starting from a cold water tank 10 up to the fitting 5. In the application shown here, all supply and discharge lines to or from the cold water tank (for example a fresh water tank of a vehicle or a mobile home etc.) 10 open below the liquid level. Furthermore, the cold water tank 10 is open to the atmosphere, such that it is always at atmospheric pressure.

[0092] The water leaves the cold water tank 10 via three paths: on the one hand, it is delivered into a warm water container 3 by a cold water pump 11, and on the other hand, it reaches the fitting 5 directly via the cold water path 4 by means of a cold water path pump 12 which is a vehicle pump, for example, to allow the desired temperature to be set by the user. Furthermore, the water from the cold water tank 10 can flow into the warm water container 3 via the outlet 13 of the container.

[0093] Water enters the cold water tank 10 and thus exits the system via the already mentioned outlet 13 from the warm water container 3. The outlet 13 is here located in the bottom of the warm water container 3 and is permanently open. Due to the position of the outlet 13 at a low point in the warm water container 3, the lowest layer of water flows out first, which is in particular the coldest layer of water.

[0094] As already indicated, water from the cold water tank 10 can also enter this lower area of the warm water container 3 when the hot water pump 20 is activateddepending on the delivery rates of the pumps 11 and 19. For this purpose, a hose or a pipe connects the outlet 13 to the cold water tank 10, the hose or the pipe opening below the liquid level in the cold water tank 10.

[0095] A water outlet temperature sensor 14 which allows the temperature of the discharged water to be measured is located between the outlet 13 and the cold water tank 10. In an alternative embodimentnot shownthe water outlet temperature sensor 14 is integrated into the outlet 13. Assuming that the coldest water flows out and a set temperature for the warm water is specified (see the specification below), it is possible to determine the degree of filling with water having the desired temperature based on the measured temperature. In addition, the measured values of the water outlet temperature sensor 14 allow the heat exchanger 2 or the associated energy unit 1 to be regulated.

[0096] First, the path of the water passing via the warm water container 3 is described.

[0097] A cold water temperature sensor 15 senses the temperature of the water delivered from the cold water tank 10 by the cold water pump 11. In one embodiment of the system, the cold water temperature sensor 15 allows the smart control of the cold water pump 11 by pilot control and/or predictive regulation. In the embodiment shown here, the cold water pump 11 is self-priming, for example a gear pump, such that it can also fill the suction line thereof with water when it is arranged above the cold water tank 10as indicated here.

[0098] In the embodiment shown, the cold water pump 11 moves the water in a loop through the warm water container 3. The loop serves as a cooling section for protecting the cold water pump 11 in the event that it is operated in the reverse direction (see to this end the description below as to the emptying of the heat exchanger 2). In an alternative embodimentnot shown herethe loop is omitted, and the cold water pump 11 delivers the water directly to the heat exchanger 2.

[0099] The water is heated in the heat exchanger 2 by using an electrical heating element as an energy unit 1, for example, or by transferring the thermal energy of flue gas or other gases, for example hot room air, which has been heated via a further heat exchangernot shown here.

[0100] A warm water temperature sensor 16 measuring the temperature of the heated water is present downstream of the heat exchanger 2. The delivery quantity of the cold water pump 11 is regulated (indicated by the dashed line) based on the measured temperature, so that a specified set temperature of the heated water is achieved. If, for example, the water is too hot, the delivery rate is increased. If it is too cold, less water is delivered. In one embodiment, the temperature measurement by the cold water temperature sensor 15 is also included in the regulation.

[0101] Regulation is performed by a control device 6not shown here, but indicated in FIG. 1, for example. In one embodiment, the control device 6 performs further steps: if, for example, the supply of thermal energy to the heat exchanger 2 is started, the cold water pump 11 is simultaneously started with a minimum delivery quantity to deliver water through the heat exchanger 2 and thus also to the warm water temperature sensor 16.

[0102] In one embodiment, the set temperature of the water to be heated is variable. This makes it possible to reduce limescale deposits in the heat exchanger 2 to be expected under certain circumstances, by reducing the temperature of the water to be heated and to be stored.

[0103] In terms of preservation of resources, it is provided in one embodiment that a heating to the highest temperature is only performed when the full nominal warm water capacity is to be retrieved soon, i.e. when the user is going to open the fitting 5 soon. This can be communicated by the user by pressing a button on the control, for example.

[0104] For the gas dissolved in the water, which produces bubbles when the water is heated, an aeration/ventilation valve 17 is present which automatically removes air bubbles from the line section downstream of the heat exchanger 2 by establishing a connection to the surroundings. The aeration/ventilation valve 17 is preferably arranged at a high point of the liquid linelike the connecting piece of the ventilation pump 19.

[0105] In one embodimentnot shown herethe aeration/ventilation valve 17 is composed of two components which each serve individual functions: one component is for discharging the air (this is realized, for example, in the manner of an automatic rapid bleeder having a float, as common in heating engineering), and one component allows air to enter the system in the event of the mentioned reverse operation of the cold water pump 11. The basic structure is as indicated in FIG. 2: a floating body is pressed by the water against an upper opening in a seal. If there is no water, the floating body falls down due to gravity and releases the opening to the environment. Air can therefore flow in.

[0106] The cold water pump 11 delivers the heated water from the heat exchanger 2 against an overflow valve 18, which, in the embodiment shown, is configured similar to a spring-loaded non-return valve, to a line portion where the water either flows into the warm water container 3 via an inlet 21 or is delivered further in the direction of the fitting 5 by a hot water pump 20. The inlet 21 is located at an upper area of the warm water container 3 such that the warm water also collects in an upper liquid layer and sinksin the direction of gravity or in the direction of the bottom of the warm water container 3due to water continuing to flow in or the outflow of the deeper water layers through the outlet 13.

[0107] The purpose of the overflow valve 18 is apparent from the following context: the overflow valve 18 is designed so as to remain closed until a certain differential pressure between the two line sides to which it is connected is exceeded. Ifas illustrated herethe warm water container 3 is located higher than the cold water tank 10, a low negative pressure is created based on the height of the water column along the warm water container 3. Therefore, if the overflow valve 18 were already opened due to this low pressure difference, the warm water container 3 would be filled with air via the aeration/ventilation valve 17 and in particular via the aerating function thereof. The overflow valve 18 is thus designed or, in the case shown here, the spring is so strong that the overflow valve 18 remains closed even if the hot water pump 20 operates at full load and thus generates a higher negative pressure in the warm water container 3 than would automatically be achieved by the water column alone. Only the delivery pressure of the cold water pump 11 can overcome the spring force or generally open the overflow valve 18 and deliver water to the warm water container 3.

[0108] Due to the overflow valve 18, a pressure loss is created in the conveyed water such that further gas can escape from the water in form of bubbles. This gas is dissipated via the ventilation pump 19. The line sections between the overflow valve 18, the hot water pump 20 and the outlet 21 are preferably designed so as to form a high point to which the gas automatically flows in that the inlet/outlet lines thereto rise continuously. The ventilation pump 19 preferably sucks off the gas at this high point.

[0109] The ventilation pump 19 acts as an non-return valve, such that in one embodimentnot shown heretwo components (one for the pump function and one for the function as a non-return valve) form the ventilation pump 19. This additional function of the ventilation pump 19 is necessary, such that the hot water pump 20 sucks only heated water and no water or gas discharged via the ventilation pump 19. In the example embodiment, the ventilation pump 19 is designed as a diaphragm pump which also fulfills the function of a non-return valve.

[0110] In one embodiment, the control device 6 activates the ventilation pump 19 automatically, while thermal energy is supplied to the heat exchanger 2. In a further embodiment, the ventilation pump 19 is operated intermittently to improve the removal of gas and simultaneously to take the smallest possible amount of hot water from the warm water container 3.

[0111] As the process of pumping out gas usually involves the pumping out of water, the return line 31 which starts from the ventilation pump 19 opens upstream of the cold water pump 11. The gas is then discharged through the aeration/ventilation valve 17. The water pumped out by the ventilation pump 19 mixes with the water from the cold water tank 10 while it is still in the suction line of the cold water pump 11, and is again guided through the heat exchanger 2. Due to the dissipation of air, no thermal energy is lost.

[0112] In one embodiment, the area of supply of the water returned by the ventilation pump 19 upstream of the cold water pump 11 is selected such that the water of the ventilation pump 19 enters the suction line of the cold water tank 10, but does not flow thereinto. In this embodiment, the returned water is thus again moved in the direction of the heat exchanger 2 by the cold water pump 11. The ventilation pump 19 is in particular operated intermittently. This leads to the advantage that a storage reservoir for warm water is formed between the cold water pump 11 and the cold water tank 10.

[0113] In one embodiment, the ventilation pump 19 is operated continuously. In an alternative embodiment, the ventilation pump 19 is operated intermittently, i.e. with interruptions. Therefore, the advantage is achieved of promoting the removal of air without discharging too much heater water.

[0114] The hot water pump 20 delivers the water in the direction of the fitting 5 and, if necessary, draws water from the warm water container 3 via the inlet 21. Depending on the delivery rate of the cold water pump 11 and the hot water pump 20, this results in the behavior of a boiler (water is taken from the warm water container 3) or of an instantaneous water heater (heated water flows directly to the fitting 5). If water is taken from the warm water container 3 via the upper inlet 21, water is filled from the bottom via the outlet 13 from the cold water tank 10 due to the negative pressure generated by the hot water pump 20. It is thus ensured that no air is present in the warm water container 3.

[0115] A branching non-return valve 22which is also spring-loaded in the embodimentand a first mixing path-non-return valve 23 are arranged downstream of the hot water pump 20. The branching non-return valve 22 is described below with respect to the emptying of the warm water container 3.

[0116] The first mixing path-non-return valve 23 ensures that the heated water moves only in the direction towards a mixing section 30 which opens onto the fitting 5. It also ensures that the cold water path pump 12, irrespective of the outlet pressure thereof, cannot press cold water backwards into the warm water container 3 via the hot water pump 20. This is relevant, for example, in the caseshown herethat the hot water pump is designed as a gear pump without any non-return valve functionality. It furthermore ensures that the pressure in the line system to the fitting 5 is maintained if no water is drawn therefrom. This is important in particular when the cold water path pump 12 is controlled via a pressure switch 26 (as in the illustrated embodiment).

[0117] In an alternative embodimentnot showna pressure reducer is additionally providedpreferably directlydownstream of the cold water pump 12, which reduces the outlet pressure of the cold water path pump 12 to a pressure level similar to that of the hot water pump 20. The two pumps 12, 20 are thus prevented from disturbing each other during their operation.

[0118] The cold water path 4 is now described for the understanding of the mixing section 30. The cold water path pump 12 delivers the water from the cold water tank 10 in the direction of the fitting 5. The cold water directly reaches the fitting 5 and also the mixing section 30 via a branching. A second mixing path-non-return valve 24 is present in the branching line from the cold water path 4 to the mixing section 30 and allows the cold water to flow only in this direction towards the mixing section 30. It is thus ensured that no hot water is guided by the cold water path pump 12 in the direction of the cold water tank 10 or the side of the cold water connection of the mixing fitting 5 in case of a low outlet pressure. This in particular applies when the cold water path pump 12 allows a backflow of the flow medium as is the case for rotary or submersible pumps, for example.

[0119] In a further embodiment (not shown), the two mixing path-non-return valves 23 and 24 may be omitted if both pumps 12 and 20 are well adapted to each other with regard to their delivery rates and pressures. This in particular applies if the pumps 12 and 20 are controlled via an electrical switch integrated in the mixing fitting, for example (not shown), rather than by means of a pressure switch 26.

[0120] The water heated to a predetermined set temperature and the cold water from the cold water tank 10 thus flow into the mixing section 30. The temperature of the mixed water is detected by a mixed temperature sensor 25. In the embodiment shown, a regulating effect is exerted onto the delivery quantity of the hot water pump 20 based on the measured temperature and a predetermined set mixed temperature. This is carried out with the target to achieve the predetermined set mixed temperature. This is therefore the maximum temperature which the water can have when flowing out of the fitting 5. A scalding protection for the user is thus provided.

[0121] In an additional or alternative embodiment, influence is exercised on the delivery quantity of the cold water path pump 12 which is a vehicle pump, for example: when combining the control of both pumps 12, 20, the control of the cold water path pump 12 leads to the advantage for the cases that the hot water pump 20 reaches its performance limit or only slightly cooled water or not so strongly heated water is present in the warm water container 30, and that the setpoint value of the mixed temperature is respectively undershot. Therefore, the amount of water at the fitting 5, for example, is reduced in favor of the constant water temperature.

[0122] In one variant, the user can specify the set mixed temperature with which the measured values of the mixed temperature sensor 25 for regulating the hot water pump 20 are to be compared. If the user then sets the fitting 5 only to hot water, he obtains water with the desired set mixed temperature.

[0123] In an alternative variantnot shownthe direct connection between the cold water tank 10 and the fitting 5 is omitted. Therefore, there is no manual mixing by the user. This is replaced by the specification of the set mixed temperature by the user and the regulation based on the temperature measured by the mixed temperature sensor 25. For example, if the user wants the water to have a temperature of 38 C., the hot water pump 20 is regulated so as to add the appropriate amount of hot water to the cold water delivered by the cold water path pump 20.

[0124] Furthermore, a pressure switch 26 is provided in the cold water path 4. It detects the actuation of the fitting 5 and the resulting pressure drop. The hot water pump 20 and the cold water path pump 12 are started based thereon, so that water is available at the fitting 5. If, in contrast thereto, the cold water path pump 12 is switched off, the hot water pump 20 is also switched off. In one embodiment, the cold water path pump 12 is a submersible pump (or a rotary pump) which is switched on, for example, by a microswitch on the fitting 5, this microswitch thus simultaneously switching the hot water pump 20 on (or off accordingly). If the cold water path pump 12 is designed as a pressure pump (for example as a diaphragm pump), the pressure switch 26 may be part of the pump 12.

[0125] The following temperatures in the system are for example relevant: the cold water has a temperature of 13 C. The temperature of the heated water is 80 C. so that germs in the water such as Legionella are avoided. The temperature of the mix of heated water and cold water is 50 C. Therefore, if the user himself mixes a water temperature on the fitting 5, it can in principle be between 13 C. and 50 C. for these exemplary values.

[0126] The following is a description of how the system allows the warm water container 3 and the heat exchanger 2 to be drained of water. To this end, the cold water pump 11 and the hot water pump 20 are configured so as to be able to deliver medium in two directions and also two different media (water as a liquid and air as a gas). They are thus self-priming. In one embodiment, the pumps 11, 20 (as illustrated) are configured as gear pumps. So far, use of the forward direction has been described.

[0127] To drain the heat exchanger 2 from water, the cold water pump 11 is reversed with respect to the delivery direction thereof. The overflow valve 18 which is located between the heat exchanger 2 and the inlet 21 of the warm water container 3 or the hot water pump 20 closes the line automatically. Therefore, no water can flow back from this side towards the fitting 5.

[0128] If the cold water pump 11 delivers in the reverse direction, air from the surroundings flows through the aeration/ventilation valve 17 into the line and in particular through the line section which extends through the heat exchanger 2. The line is thus drained, and the heat exchanger 2 cannot heat any liquid.

[0129] Emptying is important, for example, if not only liquid but also room air is to be heated by the heat exchanger 2, and if it is in particular provided that there is a pure air mode in which only room air and no liquid is heated. Furthermore, in the air mode, thermal energy which can be associated with a temperature above the boiling point of water is supplied to and transferred by the heat exchanger 2. The purpose of draining the line in the area of the heat exchanger 2 is to avoid noises or pressure surges when the liquid evaporates. Therefore, the generally cold ambient air flowing in through the aeration/ventilation valve 17 entrains water vapor produced when heat is introduced into the heat exchanger 2, before the aforementioned disturbing phenomena occur.

[0130] In this mode of operation, air and water vapor are supplied into the cold water tank 10 for draining the heat exchanger 2, where they can again escape to the environment.

[0131] In one embodiment, to reduce the risk of damage to the cold water pump 11 by such a hot vapor/air mixture, the latter can be guided and cooled in a loop through the warm water container 3 before passing the cold water pump 11 (as illustrated). The loop serves as a cooling path for protecting the cold water pump 11.

[0132] If the warm water container 3 is to be emptied for the cold season or for a longer period of non-use or for cleaning purposes, for example, the hot water pump 20 is operated in the reverse direction. Furthermore, the cold water pump 11 does not deliver any water, and the ventilation pump 19 is not active, either.

[0133] If the hot water pump 20 delivers the water away from the fitting 5 in the direction of the inlet 21 of the warm water container 3, the first mixing path-non-return valve 23 closes, and air from the environment around the arrangement can enter the line via the branching non-return valve 22 and can be delivered by the hot water pump 20 in the direction of the warm water container 3.

[0134] The branching non-return valve 22 is configured such that it does not open by the low negative pressure produced in the warm water container 3 due to the difference in height between the outlet 13 or the cold water tank 10 and the inlet 21, but only at an appropriately high negative pressure as produced by the hot water pump 20 on the side of the non-return valve 22 during operation in the reverse direction. In one embodiment, the non-return valve 22 is configured as a spring-loaded non-return valve or as an overflow valve.

[0135] The water flows out of the warm water container 3 at the bottom through the outlet 13 and is displaced by the ambient air pumped into the container 3 at the top until the warm water container 3 is empty.

[0136] The filling of the heat exchanger 2 is performed in that the cold water pump 11 pumps liquid to the heat exchanger 2in a self-priming manneras a result of which air is displaced there and exits the arrangement to the environment via the aeration/ventilation valve 17. For this purpose, the line section between the heat exchanger 2 and the overflow valve 18 is preferably configured and arranged such that the aeration/ventilation valve 17 is located at a high point therebetween.

[0137] Two variants for filling the warm water container 3 are described based on the above specification. This is realized via the ventilation pump 19, wherein the cold water pump 11 can be omitted. Alternatively or additionally, the filling is carried out via the hot water pump 20 which is operated while the fitting 5 is open and the cold water path pump 12 is not active. In both cases, water from the cold water tank 10 is sucked into the warm water container 3 via the outlet 13.

[0138] The warm water container 3 has a total of two openings: an upper opening 21 and a lower opening 13. In the specification, the upper opening 21 is referred to as inlet insofar as the heated water enters the container 3 via the inlet 21. The opening however also serves as an outlet as the hot water pump 20 can remove the heated water via this opening. The lower opening 13 is referred to as outlet insofar as water flows out via this opening when warm water or air enters the container 3 via the inlet 21. The opening however also serves as an inlet for water from the cold water tank 10, for example when the hot water pump 20 draws water from the container 3 via the inlet 21which in this case acts as an outlet. Thus, both openings 21, 13 could also each be referred to as inlet/outlet openings.

[0139] Depending on the embodiment, the system described here is composed of the components of a device for heating water and peripheral components accordingly connected thereto. In one embodiment, the system (alternative designation: arrangement) is composed of such a device and the cold water tank 10, the connection between the two being realized via an appropriate number of lines (i.e. hoses or pipes). In an alternative embodiment, the device does not include the fitting 5 so that the device is connected to the cold water tank 10 and to the fitting 5 as external components. In an alternative embodiment, the cold water path pump 12 is not part of the device but is a vehicle pump, for example, such as is commonly used in mobile homes. In this embodiment, the device therefore comprises appropriate interfaces for controlling the cold water path pump 12 or for detecting the operating state thereof. Accordingly, the fitting 5 can here also be part of the periphery of the device.

[0140] FIG. 2 further indicates a descaling device 7 which is located in the return line 31 between the ventilation pump 19 and the cold water pump 11. It is for example a device in which a descaling agent can be introduced and which adds the descaling agent to the returned liquid.

[0141] The following is a description of a descaling process which is characterized in that the least possible amount of descaling agent enters the cold water tank 10. The pumps 11, 19, 20 and the heat exchanger 2 are thus reliably descaled.

[0142] The ventilation pump 19 and the cold water pump 11 are in operation, the energy unit 1 supplying only little thermal energy to the heat exchanger 2. The delivery quantity of the cold water pump 11 is set such that the cold water temperature sensor 15 measures only the temperature of the water from the cold water tank 10 and not of the returned water. Therefore, no returned water containing descaling agent flows into the cold water tank 10. Furthermore, the water containing the descaling agent is slightly heated, which accelerates the descaling process.

[0143] The cold water pump 11 is operated so as to deliver more than the ventilation pump 19 so that water also enters the container 3. To prevent the descaling agent from entering the cold water tank 10 via the outlet 13, the hot water pump 20 is operated when the fitting 5 is open. Additionally, the cold water path pump 12 which is a vehicle pump, for example, is preferably not in operation.

[0144] Based on the temperature measurements of the mixed temperature sensor 25, the control device 6 reverses the direction of action in contrast to normal operation by setting a higher delivery quantity of the hot water pump 20 when the temperature measured in the mixing section 30 is above the setpoint value (the delivery quantity would be reduced in normal operation). In addition, a setpoint value is set which is slightly lower than the measured value of the warm water temperature sensor 16. This causes the hot water pump 20 to increase the delivery quantity by increasing its speed. It thus pumps a larger amount of water than warm water enters the container 3. It thus draws fresh water from the cold water tank 10 via the container 3. The outlet 13 of the container 3 thus allows filling from the downstream cold water tank 10. This prevents descaling agent from entering the cold water tank 10.

[0145] In one operating mode, it is provided for descaling the container 3 that the hot water pump 20 is not operated or only operated with a low delivery rate such that the heated water containing the descaling agent enters the container 3.

[0146] In one variantnot shownsieves are provided at various points of the line system which collect limescale crumbs before they render components such as valves or pumps unusable.

[0147] If the pumps used (hot water pump 20 and cold water pump 11) are gear pumps, the ability thereof to deliver air can be improved by also delivering little water therewith. The water serves quasi as a sealing means and reduces internal leakages and backflows of air. The amount of air delivered and the delivery pressure are thus increased. This in turn allows the pumps to be designed smaller or operated quietly as a sufficient amount of air is delivered. This is for example in contrast to a diaphragm pump as may be provided in one variant for implementing the ventilation pump 19.

[0148] To this end, the hot water pump 20 is considered first:

[0149] The arrangementnot shown hereis such that there is a decline of the liquid line upstream of the inlet of the pump 20. Therefore, if the hot water pump 20 delivers in the reverse direction and thus in the direction of the container 3, it first displaces water which is pushed upwards. The line which is a feed line to the pump 20 in normal operation and is located above the pump 20 against the gravitational field of the earth, usually contains some drops of water which flow back into the pump 20 when it is switched off for a short time. Sealing agent is then again present, and it can pump air better again. The hot water pump 20 is therefore operated intermittently for the delivery of air.

[0150] In one embodimentnot showna pipe thickening is provided above the hot water pump 20 so that sufficient water always runs back or downwards into the pump 20 when the pump 20 is stopped. The thickening is large enough such that the delivered air does not completely entrain the water contained therein.

[0151] The use with the cold water pump 11 is furthermore considered:

[0152] For the cold water pump 11, one embodiment is provided which is shown in FIG. 7. The return line in which the ventilation pump 19 delivers air and also water opens in an area located above the suction nozzle of the cold water pump 11. The water from the cold water tank 10 the temperature of which is detected by the cold water temperature sensor 15 accordingly also flows into this suction nozzle.

[0153] The cold water pump 11 sucks water from the cold water tank 10 itself and ventilates the heat exchanger 2, which, if necessary, has to be performed each time before water is heated: in the event of a previous aeration of the heat exchanger 2, air enters the cold water tank 10 through the cold water pump 11.

[0154] According to the embodiment of FIG. 7, the following is alternatively provided: the ventilation pump 19 pushes small amounts of water at intervals via the return line in front of the suction nozzle of the cold water pump 11. Therefore, the pump 11 always has sufficient sealant for the suction from the cold water tank 10 to suck efficiently. The upright suction nozzle of the cold water pump 11 favors the inflow of water.

[0155] In the arrangement of FIG. 2, three lines lead to the cold water tank 10: one line for drawing water which is to be heated, one line for drawing cold water for the fitting 5 or the mixing section 30, and one line via which the water from the outlet 13 of the container 3 flows into the cold water tank 10. To provide a frost protection of these lines, the lines are arranged adjacent to each other in one embodimentnot shown hereso that there is one common hose having three ducts. The end areas of the ducts in the cold water tank 10 are sufficiently spaced apart from each other such that water is prevented from flowing from one duct directly into another one.

[0156] This embodiment with the parallel lines allows an elegant way of heating the lines to prevent frost: in the event that the arrangement is not operated or that at least no warm water is produced, the ventilation pump 19 is occasionally operated to guide a low amount of warm water via the return line into the hose connecting the cold water tank 10 to the cold water pump 11 which is not active during these periods. This warm water thus also heats the adjacent hoses or ducts. This process is performed in a temperature- and/or time-controlled manner. Freezing of the hose is thus prevented.

[0157] FIG. 3 again shows the system of FIG. 2 to describe the individual functional units separately. For the sake of clarity, individual reference numerals are omitted; rather, reference is made to FIG. 2. The specification respectively also applies accordingly to the arrangement according to the second teaching, as shown by way of example in FIG. 5.

[0158] The system comprises a functional block A in which the set temperature of the heated water is regulated.

[0159] To this end, the temperature of the water heated after the contact with the heat exchanger is measured, and on this basis, the cold water pumphere by way of examplewhich delivers the water to be heated through the heat exchanger, is regulated accordingly. The pump delivery quantity is thus regulated continuously, so that water at the desired temperature flows to the inlet of the warm water container or further in the direction of the fitting. The heated water flowing into the warm water container displaces the water which is contained therein and is in particular cold. (As will be discussed below, the arrangement according to the second teaching of the invention causes the container 3 to expand). The cold water flows out of the warm water container, and the warm water container fills with the water which is at the desired temperature and can also be delivered to the fitting. As already mentioned, the pump function can be assumed by the cold water pump, the ventilation pump or the hot water pump.

[0160] The functional block B serves to discharge the air dissolved in the water which is released when the water is heated. Furthermore, the air can be removed which is contained, for example, in the still empty warm water container or the still empty heat exchanger prior to an initial filling.

[0161] This is intended to prevent air from collecting in the warm water container which would disturb the operation of the hot water pump and furthermore would lead to the admixture of air at the tapping fitting. Air in the container would also have negative effects on the usable thermal capacity of the container.

[0162] The air released from the water during heating escapes from the line system via an aeration/ventilation valve. If air remains in the water downstream after the passage through the aeration/ventilation valve, a pressure drop at an overflow valve causes it to escape from the water and to be discharged via a ventilation pump. The air and any water also delivered along therewith due to pumping are reintroduced into the line section for the heating of water upstream of the heat exchanger. The airnow in the undissolved statethus again reaches the aeration/ventilation valve and is discharged to the environment there. The thermal energy of the water is not lost as the water is recirculated.

[0163] Operation of the cold water pump is not necessary for the initial filling of the warm water container. In this case, the air sucked off via the ventilation pump is discharged into the fresh water tank.

[0164] In the functional block C, a constant discharge temperature of the water is set which does not exceed a maximum value limit. This block C is present in the arrangement according to both teachings.

[0165] In the mixing block C, the heated water and the cold water are mixed such that the water dispensed via the fitting cannot be warmer than a maximum temperature. This prevents a scalding of the user and also provides a comfort function. The maximum temperature is lower than the set temperature which is produced by the heating block A.

[0166] To this end, a mixing section is provided into which the heated water is introduced via a hot water pump and the cold water is introduced via a pump. A mixed temperature sensor detects the temperature in the mixing section and regulates the delivery quantity of the heated water based on the measured value. In one embodiment, the mixing block C allows the setting of the temperature with which the water is to be discharged from the fitting, i.e. from the water tap or a shower head, for example. The manual regulation of the temperature by the user is thus omitted. The user only has to enter a setpoint value. In one embodiment, the delivery quantity of the cold water is alternatively or additionally regulated.

[0167] In one embodiment, the mixing block C is a separate device which is connected to further components at the periphery via appropriate interfacesin particular with respect to the transport of liquid.

[0168] The functional block D serves to switch on the mixing block C.

[0169] If, for example, a pressure switch or a microswitch integrated in the fitting detects that the fitting is open and water flows out, the pumps for the cold water and for the warm water are switched on. Mixing then also takes place through mixing block C. The heated water comes directly from the heat exchanger and/or is removed from the warm water container. After the opening of the fitting, water is immediately available to the user.

[0170] The functional container emptying block E serves to empty the warm water container. This applies to the arrangement according to the first teaching. The emptying of the container 3 in an arrangement according to the second teaching is described below.

[0171] For emptying, the pump delivering the heated water in the direction of the fitting is operated in the reverse direction. A non-return valve or an overflow valve connected to the ambient air thus opens. The non-return valve allows the air to flow in only one direction and only if there is a certain pressure difference. The pump thus first delivers water present in the line, and then air to the inlet of the warm water container. Pumping also causes the mentioned pressure difference for admitting the air via the non-return valve. In normal operation, the pump removes the water from the warm water container via the inlet. As the pump which is active in the heating block A and delivers the cold and the heated water in the direction of the warm water container there during normal operation, is switched off, no new water flows from there in the direction of the inlet. The ventilation pump is furthermore switched off. The water flows out of the warm water container via the outlet, and the pump operated in the reverse direction empties the warm water container.

[0172] It may be necessary to exclude a heating of the water through the heat exchanger. This is the case, for example, if the heat exchanger is to heat air and no water in one mode of operation. Water remaining in the line would evaporate and cause noises. The functional heat exchanger emptying block F is therefore provided. Block F can again be implemented in both teachings.

[0173] In this functional block F, the pump delivering the water to be heated is operated in the reverse direction and thus draws back the remaining water from the area of the heat exchanger. This is supported by the aeration/ventilation valve which has already been described in the context of the venting block B and acts as an aerating valve in this case of operation. Therefore, air from the environment enters the line and pushes the remaining water in the direction of the pump operated in the reverse direction.

[0174] A further functional blockwhich is not shown for the sake of clarityserves to descale the pumps 11, 19 and 20 and the heat exchanger 2. Here, reference is made to the above description of FIG. 2.

[0175] FIG. 4 shows part of a variant of the system described above. In this embodiment, the previously heated water from the warm water container 3 flows from the outlet 13 into a grey water tank 27 which has a gray water tank non-return valve 29 arranged upstream thereof. The valve 29 allows only a flow in the direction of the gray water tank 27. The cold water flows out of the cold water tank 10 via a cold water tank non-return valve 28 and through the outlet 13, which thus acts as an inlet in this case, and into the lower area of the warm water container 3. The outflow of the water into the gray water tank 27 and the inflow of the water from the cold water tank 10 are adjusted to each other such that no air enters the warm water container 3. This variant prevents heated water from entering the cold water tank 10.

[0176] FIG. 5 shows an alternative to the variant of FIG. 2 and FIG. 3., respectively. This is an example for the second teaching. Merely the differences will be discussed below. The previous explanations apply to the component which are not discussed.

[0177] The warm water container 3 does not have a fixed but a variable liquid volume. This is indicated here by a bladder. The container 3 can thus expand depending on the degree of filling. A supporting structure such as a grid is for example located around the bladder as the actual container 3.

[0178] Furthermore, the container 3 has only one opening 21, which can be located at any position and here at the top only by way of example. The container 3 is designed such that no air collects therein when it is filled with liquid. For this purpose, the container 3 is for example designed accordingly to be smooth and free of protrusions or folded areas, etc.

[0179] In particular, the air is sucked off at a high point above the opening 21 by the ventilation pump 19 before it can enter the container 3.

[0180] The two teachings have in common that the container 3 is completely filled with liquid during the heating operation of the device or arrangement and that there is no air therein. This is achieved here, for example, by the container 3 contracting when liquid is removed instead of cold water flowing in from the cold water tank.

[0181] Accordingly, the arrangement in FIG. 5 does not require a branching non-return valve 22, which in the arrangement in FIG. 2 made it possible to empty the container with a fixed internal volume via the hot water pump 20. As this type of emptying of the container 3 is not required, it is sufficient if the hot water pump 20 only delivers in the direction of the fitting 5. The pump 20 can therefore also be a diaphragm pump, for example.

[0182] As the container 3 does not have a second, permanently open opening as in the variant of FIG. 2, the operating behavior of the arrangement changes:

[0183] When the container 3 has reached its maximum internal volume, no further water can be pumped thereinto by the cold water pump 11. Therefore, either the hot water pump 20 must start to remove water or the cold water pump 11 must be stopped. In the second alternative, the supply of thermal energy to the heat exchanger 2 is also stopped, as the exchanger 2 could otherwise overheat.

[0184] The ventilation pump 19 can be used to purposefully and completely empty the container 3thus for example the bladder. The cold water pump 11 must be switched off therefor. The ventilation pump 19 drains the container 3 and pumps the water back into the fresh water tank 10 via the suction hose of the pump 11.

[0185] A fundamental difference between the two arrangements is that in the arrangement according to the second teaching of FIG. 5, in the event that the water in the bladder 3 has cooled down due to heat loss to the outside, it must first be pumped out if hot water is required before the heat exchanger 2 and the cold water pump 11 can be put into operation. In the arrangement according to the first teaching in FIG. 2 with the two openings in the container, the heating of water via the heat exchanger 2 can begin immediately.

[0186] FIG. 6 shows an embodiment according to the first teaching of the invention. The application to the second teaching is obvious.

[0187] Part of the arrangement around the container 3 is shown. The overflow valve 18, the ventilation pump 19 and the hot water pump 20 can be seen above the container 3not only graphically, but also in relation to the realized geometry. An additional tank 3 is located downstream of the outlet 13 of the container 3 in flow direction. In particular, the additional tank 3 is arranged relative to the container 3 such that the hydrostatic pressure in the container 3 remains unchanged. The additional tank 3 therefore only increases the capacity. Therefore, the container 3 and the additional tank 3 could also be considered as one unit for receiving the liquid. An outlet opening 13 of the additional tank 3 is coupled to the fresh water tank 10. In this embodiment, the container 3 is therefore indirectly connected to the fresh water tank 10.

[0188] The variant of the arrangement in FIG. 6 can also be transferred accordingly to the arrangement shown in FIG. 5. However, the additional tank 3 then does not have an outlet opening 13.

[0189] In addition to the water outlet temperature sensor 14, the additional tank 3 also includes an additional tank temperature sensor 14, the measured values of which are used to control the arrangement.

[0190] FIG. 8 shows a connection of the arrangement to a fixed water connection 40. To supply the cold water tank 10 with water, a float valve 41 is provided as an example in the embodiment shown, which ensures automatic refilling.

[0191] In addition, the arrangement is designed such that it is possible to dispense with the operation of the cold water path pump 12. This is desirable, for example, if it is a vehicle pump which is designed as a pressure pump to reduce noise generation.

[0192] For this purpose, the fixed water connection 40 is not only connected to the cold water tank 10 via the float valve 41, but there is also a connection upstream of the valve 41 into the cold water path 4. The access opens downstream behind the cold water path pump 12. After the fixed water connection 40 and before the branch to the cold water path 4, there is a first non-return valve which prevents water from being pumped into the water network. A second non-return valve which prevents the cold water tank 10 from being filled backwards via the cold water path pump 12 is arranged downstream of the cold water path pump 12 and upstream of the access from the fixed water connection 40.

[0193] Preferably, the float valve 41 is automatically locked when the fixed water connection 40 is not connected to the arrangement. This prevents the cold water path pump 12 from only pumping in a circuit via the float valve 41 when the level in the cold water tank 10 is low, instead of building up pressure at the fitting 5.