ORDER FOR HEATING A LIQUID

Description

[0001] The present invention relates to an arrangement for heating a liquid. Additionally, the arrangement serves to heat a gas, e.g., room air. The liquid is, for example, process water.

[0002] It is known in the art to obtain thermal energy from the combustion of, for example, propane, butane, or diesel fuel converted into a gaseous state, or by using electricity, and to transfer this energy to a liquid, e.g., domestic hot water, via a heat exchanger (see, e.g., WO 2020 / 108908 A1). It is also known that such devices can additionally serve as air heaters.

[0003] Normally, devices for heating a liquid are operated like an instantaneous water heater or a boiler. This means that either the heated water is dispensed directly after passing through a heating circuit, or water is heated in a container so that the user can draw it as needed. From the user's perspective, an instantaneous water heater is very convenient. However, to provide a large quantity of hot water, a correspondingly high heating output is required. If a lower heating output is sufficient, a buffer storage tank – similar to a boiler – is necessary for the hot water. Buffer storage tanks are described, for example, in DE 20 2011 003 668 U1 or DE 89 13 252 U1. A disadvantage of such buffer storage tanks (or liquid containers) is that the heat source is usually installed at the bottom, which disrupts the temperature stratification within the storage buffer.Furthermore, a significant portion of the total volume must be heated before water of the desired temperature is available.

[0004] US patent 2013 / 0312671 A1 discloses a demand-controlled, tankless system for heating water, comprising a primary and a secondary heating system located in a buffer tank, which control the outlet water temperature. A differential pressure switch detects low flow demand and allows the secondary heating system to heat the water immediately.

[0005] The invention is based on the objective of proposing a method for providing heated liquid that departs from the known principles of instantaneous water heaters and boilers, thus representing an alternative to the prior art. This method should preferably be characterized by avoiding the disadvantages of a boiler, even in cases where only a low heating capacity, insufficient for operation as an instantaneous water heater, is available.

[0006] The invention solves the problem by means of an arrangement for heating a liquid, comprising an energy unit, a heat exchanger, a container and a pump, wherein the energy unit supplies the heat exchanger with thermal energy, wherein the heat exchanger transfers the thermal energy to the liquid, wherein the container receives the liquid, wherein the container has an opening, and wherein the pump is connected to the opening of the container and to the heat exchanger in such a way that the pump pumps liquid out of the opening and / or from the heat exchanger.

[0007] According to the invention, an arrangement is provided which represents a combination of an instantaneous water heater and a boiler. A pump delivers liquid either from in front of the heat exchanger (this would be the instantaneous water heater) or from a container for the liquid (this would be the boiler). If more liquid leaves the heat exchanger than is delivered by the pump, e.g., towards a tap as a dispensing point, liquid flows into the container through the opening. If the pump delivers more liquid, it draws liquid from the container through the opening. If the pump delivers as much liquid as leaves the heat exchanger as heated liquid, the opening of the container, and thus the container itself, is bypassed. The pump therefore delivers, in particular, heated water away from the heat exchanger.

[0008] Additionally, another pump is provided, which circulates the fluid to be heated through the heat exchanger, and the opening of the container is located between the heat exchanger and the pump. In one of the following embodiments, the second pump is referred to as a cold water pump. The second pump circulates the fluid through the heat exchanger, where it is heated. The flow rates of both the first and second pumps are therefore crucial in determining whether fluid enters or leaves the container.

[0009] Furthermore, a vent valve and a return line are provided. The vent valve allows air to be released from the assembly, and a vent pump is provided to remove air and liquid through a return line. This return line terminates before the vent valve and before the subsequent pump. In this configuration, air is removed from the heated liquid via a vent valve, which in this context can be a simple vent valve. A vent pump is located downstream of the vent valve and pumps air (or gas, generally) and liquid into a return line. This removes the air, preventing it from reaching, for example, the fitting. Since the removed liquid is already heated, it is introduced before the intake of the subsequent pump.This ensures that the fluid is pumped back through the heat exchanger, preventing the loss of thermal energy. The air in this fluid also passes through the heat exchanger and returns to the air release valve.

[0010] One embodiment provides for a temperature sensor to measure the temperature of the fluid heated by the heat exchanger, and a control device that receives readings from the temperature sensor and uses them to control the subsequent pump. In this embodiment, the temperature of the heated water is regulated.

[0011] One embodiment involves a pump that delivers heated liquid to a mixing section, which includes a cold water path leading to the mixing section. A mixing temperature sensor measures the temperature of the liquid in the mixing section, and a control device, based on the sensor readings and a predefined temperature range, controls the pump and / or a cold water path pump to deliver the liquid in the cold water path. In this embodiment, the heated liquid is cooled to a predefined temperature range. This serves, for example, as scald protection. For this purpose, the heated liquid is mixed with cold or unheated liquid in a mixing section.Based on the temperature of the liquid in this mixing section, at least one pump's delivery rate is regulated: This is either the pump that delivers the heated liquid, or a cold water path pump that delivers the unheated liquid.

[0012] Another design involves a component located between the venting / de-aeration valve and the venting pump. This component opens when a predetermined pressure differential is exceeded, allowing the fluid to flow towards the venting pump. A sufficient pressure difference must therefore exist between the two sides of this component. This pressure difference can also cause air to be released.

[0013] A supplementary embodiment provides that the air release / vent valve not only serves for venting but also allows air to enter the system's piping. In this case, the additional pump is designed to pump air through the heat exchanger in one direction and liquid through the heat exchanger in another. The air entering from the outside via the air release / vent valve, which in one embodiment consists of two separate units—one for venting and one for de-venting—serves to empty the heat exchanger.

[0014] One embodiment provides for a descaling device, the descaling device being arranged along the return line in such a way that it adds a descaling agent to the liquid pumped by the venting pump. In this embodiment, a descaling agent is added to the returned liquid.

[0015] According to a first teaching, an arrangement for heating a liquid is provided, comprising an energy unit, a heat exchanger and a container, wherein the energy unit supplies the heat exchanger with thermal energy, wherein the heat exchanger transfers the thermal energy to the liquid, wherein the container receives the liquid, wherein the container has at least two openings, and wherein there is a height difference between the two openings, such that a hydrostatic pressure difference is established.

[0016] The arrangement according to the invention comprises at least one energy unit, a heat exchanger, and a container. The heat exchanger transfers the thermal energy generated by the energy unit—e.g., by applying an electric current or by burning a fuel-air mixture—to the liquid, thus heating it.

[0017] The container holds the liquid. It has two openings at different heights, creating a hydrostatic pressure difference between them. One opening is thus higher than the other in the direction of Earth's gravity. Consequently, the liquid introduced through the upper opening displaces the liquid already present in the container through the lower opening. This allows, for example, the container to be slowly filled with heated liquid through the upper opening, with the cooler liquid flowing out through the lower opening due to the temperature-related density difference. Conversely, it is also possible to remove liquid through the upper opening, which can lead to automatic refilling through the lower opening.By filling and removing the liquid through an opening, the opposite process (i.e., emptying or filling) can be triggered.

[0018] Accordingly, during operation, the arrangement is such that both openings of the container are open, thus allowing the passage of liquid. In particular, one opening – the upper one – is connected to the other components, e.g., via hoses or pipes. Preferably, the other opening is also connected – e.g., via at least one hose or pipe – to a cold water tank (e.g., a fresh water tank of a vehicle or caravan).

[0019] The container, with its openings, can thus be considered a type of hose (or pipe) with a larger capacity. The connection to the surrounding components (i.e., pumps or standard liquid / air lines, etc.) is such that liquid is introduced into and extracted from this container-hose in both directions. The imaginary hose is positioned in the gravitational field such that one opening to this larger capacity is located above the other opening.

[0020] If the container is connected to atmospheric pressure via at least one opening, the advantage is that a safety valve, as required for a pressurized container according to the prior art, is not necessary. In this arrangement, for example, the lower opening is connected to a tank that is open and therefore at atmospheric pressure. In practice, it is preferable that the lower opening is connected to the tank via a hose or pipe, and that this hose or pipe terminates below the liquid surface of the tank. The hose end should therefore be submerged. This prevents the container from emptying or air from entering it from below, even if it is located above the tank.

[0021] Due to the design and arrangement of the container, as well as its use, no air bubbles are present. Under normal operating conditions, the container is therefore completely filled with liquid. Since there are no air bubbles, its entire volume can be used to supply heated liquid, thus enabling a small overall volume. If the liquid expands due to thermal expansion, this additional volume is released through the lower opening into the aforementioned components, such as a fresh water tank. Therefore, expansion tanks with gas cushions are not required.

[0022] By draining the liquid from one opening of the container while filling it through the other, the advantage arises that, for example, the energy unit can operate continuously. Thermal energy is continuously dissipated via the heat exchanger and the liquid, even if the liquid in the container is already fully heated. Therefore, the energy unit needs to be started and stopped less frequently, thus avoiding, for example, the energy expenditure during startup or the risk of a generally detrimental starting process. For example, there is also no waiting time that might be required before the energy unit can be restarted. Fewer combustion chamber purging cycles are also necessary to prepare the energy unit. This is a significant advantage, for instance, if the energy unit burns a fuel such as diesel fuel to generate thermal energy.It is particularly advantageous to be able to operate the burner for a certain minimum burn time, even when the tank is already completely filled with heated liquid. This reduction or elimination of numerous start / stop cycles of the energy unit, which involve waiting times, enables a high hot water availability with a significantly smaller tank volume.

[0023] In one embodiment, the energy unit, the heat exchanger, and the container form a heating device that serves to heat the liquid and is connected to other components to form an assembly (alternatively termed a system). The assembly would thus be the device plus other components in its periphery. Therefore, in one embodiment, the device has corresponding interfaces to connect to the other components. In one embodiment, another component is, for example, an additional container that increases the capacity of the main container. From a functional perspective, the combination of the main container and the additional container can be considered a single unit.

[0024] Preferably, a control device is also provided in which target values ​​are stored or can be stored, which receives measured values ​​and which, based on these target values ​​and measured values, controls components of the heating device and / or the arrangement. Control is generally understood as intervention in another unit with regard to its settings or its operating mode. Control thus dictates what this unit does and to what extent. The term "control" can therefore encompass both control in the narrower sense and regulation.

[0025] According to a second teaching, the arrangement for heating a liquid is provided with an energy unit, a heat exchanger, a container, and a control device, wherein the energy unit supplies the heat exchanger with thermal energy, the heat exchanger transfers the thermal energy to the liquid, the container receives the liquid, the container has an opening, and the container has a variable liquid volume. In this alternative teaching of the invention, the container preferably has only a single opening through which the liquid is introduced and from which it is drawn, and which is connected to other components of the arrangement. Such an opening is to be separated, for example, from a passage through which the liquid can pass from the actual container to an additional container or tank.Such an additional tank only increases the internal volume of the entire container assembly consisting of the main tank and the additional tank. Furthermore, the container has a variable liquid volume. The container can therefore expand and contract like a bladder, so that the amount of liquid it can hold can vary between a minimum and a maximum value.

[0026] In one embodiment, the container is supplemented by an additional container or tank. The combination of container and additional tank has only one opening to the other components of the arrangement or the surrounding periphery. Openings may exist between the container and the additional tank, but the liquid flows only through these openings within the combined unit.

[0027] Both inventions share the common feature that the containers are used in such a way that they contain only liquid and no air. This is achieved either – in the first invention – through the two openings in the container through which the liquid passes, or – in the second invention – through the variable capacity of the container to hold different quantities of liquid.

[0028] According to one embodiment of the second teaching of the invention, the arrangement is implemented according to one of the aforementioned or subsequently described variants. These embodiments also apply accordingly to the arrangement according to the first teaching.

[0029] According to the aforementioned second teaching, the container has only one opening, but a variable liquid volume. For this container, which, for example, has a variable liquid volume, some of the following embodiments apply – just as they do for the container with two openings.

[0030] According to one design, the container is at least partially made of plastic. The use of plastic is possible because the container—apart from the generally negligible hydrostatic pressure—does not have to withstand any internal pressure. The material used is characterized by its low weight and almost unlimited design possibilities. Furthermore, the construction is usually inexpensive. A plastic or a type of plastic is also used, for example, in the container with the variable liquid volume.

[0031] One design involves a container with the smallest possible volume. This reduction is possible because it eliminates the need to store a large quantity of heated liquid; instead, any demand for heated liquid exceeding the container's volume is met directly by heating additional liquid via the heat exchanger. Reasons for a small container volume include the following: In conjunction with the scald protection design—discussed below—for example, through the control of the hot water pump or the cold water path pump, it is possible to store liquid at a high temperature in the container.

[0032] If the energy constantly supplied to the heat exchanger is dissipated via a consistently high temperature difference in the fluid it circulates, the volume flow of heated fluid into the container remains consistently small. Such a low flow rate ensures that temperature stratification within the container is hardly disturbed.

[0033] Since the container – with the two openings according to the first doctrine – is in pressure equalization with the atmosphere via one opening, and thus, for example, no internal overpressure can build up in it when the liquid is heated, no gas bubble is required for pressure limitation.

[0034] The absence of an air bubble improves stratification because turbulence is avoided.

[0035] The tank volume is determined solely by the requirements of the hot water demand and does not need to include any additional volume to meet the requirements regarding combustion in the energy unit as a heat sink (e.g., due to minimum operating times or waiting times).

[0036] According to one embodiment, the container is designed to allow for virtually complete emptying of the liquid. This serves, among other things, hygiene purposes. No liquid remains in which germs could, for example, form during a prolonged period of disuse. Complete emptying is also advantageous when descaling or other chemical cleaning of the device is required.

[0037] According to one embodiment, the container is connected, or connectable, to a fresh water tank via an opening. The fresh water tank is, for example, part of a vehicle, caravan, motorhome, or boat in which the system is installed. The liquid—i.e., water—to be heated is preferably drawn from the fresh water tank. If the container's opening is connected to the fresh water tank, allowing the liquid—heated at least during operation—to exit the container, active heating of the fresh water tank is possible, thus preventing it from freezing.

[0038] One embodiment involves a pump for circulating the fluid through the heat exchanger, a temperature sensor for measuring the temperature of the fluid being circulated, and a control device that receives readings from the temperature sensor and uses them to control the pump. In this embodiment, regulation takes place to ensure the heated fluid reaches a predetermined target temperature. For this purpose, the temperature of the fluid downstream of the heat exchanger is measured. Based on this actual value, the pump is then controlled to adjust the flow rate. In one of the following embodiments, this pump is, for example, a cold water pump connected to a cold water tank, such as a vehicle's fresh water tank.By regulating the temperature of the heated liquid, the advantage arises that the volume of the container can be optimally used to store liquid at a consistently high temperature, regardless of the temperature of the cold liquid or the thermal energy supplied to the heat exchanger, i.e., the degree of heating that the heat exchanger can achieve based on this energy input.

[0039] One embodiment consists of a pump connected to one of the two openings of the container and to the heat exchanger. When the pump draws liquid from the container through one opening, liquid flows into the container through the other. In this embodiment, a pump is provided that can draw liquid from the heat exchanger and / or from one opening of the container. It thus moves liquid heated by the heat exchanger and / or liquid already in the container, for example, towards a valve through which liquid can be drawn from the system. When liquid is drawn from the container through one of the two openings, liquid is replenished through the other opening, preferably in the same quantity. The container is therefore not emptied, but remains full.In one embodiment, the liquid flowing in through the other opening is cold and, in particular, not a liquid that has been heated by the heat exchanger. In this embodiment, the opening through which the pump draws the liquid from the container is the upper opening.

[0040] In one embodiment, particularly for the arrangement according to the second teaching with the variable liquid volume, a pump is provided, which is connected to the opening of the container and to the heat exchanger, and in the event that the liquid volume of the container decreases when the pump draws liquid from the container via the opening. The container thus contracts, for example, when liquid is drawn from it.

[0041] The pump for conveying the liquid from the heat exchanger and the container is, in one of the following configurations, for example referred to as a hot water pump.

[0042] In one embodiment, a pump extracts heated liquid from the container or pumps liquid that has been heated directly by the heat exchanger. If, in this embodiment, heated liquid is extracted from the container for such a long time that no heated liquid remains, i.e., its usable heat capacity is exhausted, the pump (for example, the hot water pump according to one embodiment) primarily pumps liquid directly from the heat exchanger, thus reaching the outlet of the arrangement, e.g., a fitting. Therefore, the function of the instantaneous water heater is advantageous in this case, so that, in particular, no sudden change from heated to cold liquid occurs, as can happen with boilers.

[0043] According to one embodiment, a venting / air release valve is provided, and this valve allows, depending on the application, the supply of air to the assembly or the discharge of gas from the assembly. In this component, gas (e.g., air) is discharged from the assembly or air (especially ambient air from the area surrounding the assembly) is supplied via a valve or valve assembly. Discharge of air also refers to gas released from the liquid when it is heated—for example, due to reduced solubility. Supply of air allows for the emptying or pressure-draining of at least parts of the assembly.

[0044] In one embodiment, the venting / air release valve is a single component that performs the dual function. In an alternative embodiment, there are two separate components that are considered a single functional unit.

[0045] One embodiment provides for a vent valve, a vent pump for removing gas and liquid, and a return line positioned upstream of the vent valve and a pump that circulates the liquid through the heat exchanger. When the liquid is heated, gases or, for example, air dissolved in the liquid can escape. To prevent this air from reaching a fitting or entering the container, a vent valve is provided. This vent valve is preferably connected to the line carrying the liquid heated by the heat exchanger. Furthermore, a vent pump is provided to remove air and liquid. In one embodiment, the vent pump is located downstream of the vent valve.The venting pump also removes fluid that has already passed through the air release valve. This fluid, and therefore any air, is routed through a return line that terminates before a pump and the air release valve. The pump circulates fluid through the heat exchanger. This returned fluid then passes the air release valve again to remove any remaining air, thus increasing the venting effect. Therefore, in this design, only the venting function of the air release valve is relevant, meaning that in one configuration, the valve can be reduced to a simple venting valve. Furthermore, the returned fluid is routed through the heat exchanger again, following the same path as the fluid being heated but not returned.The thermal energy already transferred is therefore not lost, but is transferred to the liquid to be heated.

[0046] In one embodiment, the venting pump is also connected to an opening in the container, so that venting of the container is possible via this opening.

[0047] In one embodiment, the function of the venting / air release valve is divided between two separate valves: one valve serves for venting, allowing air escaping from the heated liquid to be discharged from the assembly. Another valve serves for aeration, allowing ambient air to drain the heat exchanger. Alternatively, as mentioned above, a single valve can perform both functions.

[0048] In one embodiment, the venting pump is operated intermittently rather than continuously. Studies have shown that by interrupting the pump's operation with pauses, the amount of air that can be extracted can be increased without a corresponding increase in the amount of liquid discharged during pumping. Therefore, significantly more gas can be removed.

[0049] In a further embodiment, the return line terminates relative to a supply line of a pump that delivers the fluid to be heated to the heat exchanger. The outlet area and the effective pumping capacities of the venting pump and the pump are coordinated such that the returned fluid is essentially delivered more strongly by the pump towards the heat exchanger than by the venting pump delivering the fluid into the supply line. In other words, the venting pump only moves the returned fluid far enough in the return line to the supply line that the pump takes over the further delivery. In one embodiment, the venting pump is designed such that, at least briefly (this is associated with intermittent operation of the pump), it delivers a higher flow rate than the pump delivering the fluid to be heated.Due to the intermittent operation, the recirculated fluid does not reach the end of the supply line into which the venting pump delivers liquid and gas or air, but only flows in that direction. This advantageously creates a "reservoir" of heated fluid from which the pump draws fluid when circulating the fluid to be heated. This capability of the pump is based on the fact that the return line terminates before the cold water pump. As investigations have shown, the briefly high pumping capacity of the venting pump is advantageous for entraining the gas bubbles. In one of the following embodiments, the pump for circulating the fluid to be heated is designated as the cold water pump.

[0050] One embodiment involves a component located between the air release / venting valve and the venting pump. This component only opens when a predetermined pressure differential is exceeded, allowing the fluid to flow in one direction. The flow direction is away from the heat exchanger and towards the tank. Thus, this component only allows the fluid to flow in one direction when a certain pressure differential is present. This component prevents the tank from filling with air through the air release / venting valve due to the hydrostatic vacuum created at its upper end by its height and position, and prevents the heated water from escaping through the lower end of the tank. This is particularly important in embodiments where the tank is located above the cold water tank.The pressure drop in the liquid caused by the flow through this component causes further gas to escape from the liquid, which can be removed via the venting pump.

[0051] One embodiment provides that air can also be introduced into the arrangement via a component, preferably the air inlet / vent valve, and that a pump (in one embodiment, for example, the cold water pump) is present to circulate the air introduced via this component through the heat exchanger. This embodiment—preferably in conjunction with the aforementioned component, which only opens when a pressure differential is present—allows the heat exchanger to be emptied without simultaneously emptying the container. This is relevant, for example, if the heat exchanger is intended to heat air, such as room air, in addition to the liquid. In this case, emptying the container prevents the liquid in the heat exchanger from being heated and evaporating while the air is being heated. The introduced air is, in particular, ambient air from the room outside the arrangement.In one configuration, the pump is operated until the heat exchanger is empty.

[0052] The aforementioned component for introducing air is implemented as follows: A sphere with a lower density than the heated liquid, e.g., water, is present and is pressed upwards by the liquid against a seal. This causes the sphere (or a suitably shaped float) to close an opening within the seal to the atmosphere. If no liquid is present below the sphere, for example, because it is being pumped out, the sphere falls due to gravity, and the opening is no longer sealed. Therefore, air can enter.

[0053] One embodiment involves the pump pumping air through the heat exchanger in one direction and liquid through the heat exchanger in another direction. In this embodiment, a single pump (for example, a chilled water pump) is provided that can pump two different media (liquid and air) in two different directions. Alternatively, a separate pump is provided for each medium and for each direction.

[0054] One embodiment provides that a pump delivers the heated liquid to a mixing section, that a cold water path leads to the mixing section, and that a mixing temperature sensor is present to measure the temperature of the liquid in the mixing section. In this embodiment, the temperature of the heated liquid, which has been warmed by passing through the heat exchanger, is reduced to a predefined mixing temperature. For this purpose, the heated liquid is mixed with cold, i.e., unheated, liquid in the mixing section. A temperature sensor is provided for setting the temperature of the liquid in the mixing section. Controlling the temperature in the mixing section (e.g., by adjusting the flow rate of at least one pump that delivers heated / hot or cold liquid to the mixing section) ensures that liquid at a constant temperature is dispensed, for example, at the tap.In one embodiment, both the temperature of the heated liquid (e.g., via the control of the cold water pump) and the temperature of the mixed liquid are controlled. In one of the described embodiments, the pump that circulates the heated liquid is referred to as the hot water pump. In one embodiment, tempering the liquid in the mixing section allows the liquid in the heat exchanger to be heated to a sufficiently high temperature, e.g., to kill germs, while still preventing scalding, for example, from a faucet or showerhead. To increase the level of safety, electronic components used to control the mixing process are redundantly designed to ensure this scalding protection.As already mentioned, regulating the temperature of the heated liquid also has the advantage that the volume of the container can be used optimally to store liquid at a consistently high temperature – regardless of the temperature of the cold liquid or the thermal energy supplied to the heat exchanger.

[0055] In one embodiment, both the quantity of heated liquid supplied to the mixing section and the quantity of cold liquid supplied to the mixing section are regulated. The cold liquid, which originates, for example, from the cold water tank from which the liquid to be heated is drawn, is supplied by a cold water path pump in one embodiment. In another embodiment, this pump is the vehicle pump of the vehicle in which the system is installed.

[0056] In one embodiment, the control device, based on measured values ​​from the mixing temperature sensor, controls the pump and / or a cold water path pump for conveying the liquid in the cold water path such that the temperature of the liquid in the mixing section remains essentially within a predetermined temperature range under varying pressure conditions in the mixing section and / or in the area of ​​the pump or the cold water path pump and / or under varying flow rates of the liquid in the mixing section and / or in the area of ​​the pump or the cold water path pump. Throughout this description, the control of a pump preferably refers to its flow rate. The temperature range is preferably a tolerance range around a setpoint. In other words, the temperature sensor, which measures the temperature of the liquid in the mixing section, allows for temperature control of the liquid, which, for example,The system dispenses warm liquid, or specifically warm water, via a fitting. The temperature is kept essentially constant, preferably independent of pressure conditions and also preferably independent of flow rates within the system. In one embodiment, the flow rate refers to the flow rate in the mixing section and therefore also to the quantity drawn from the system via a fitting.

[0057] In one embodiment, the pump that delivers the heated liquid to the mixing section is activated when warm liquid is drawn off, for example, at a tap. This activation can be achieved via electrical contacts at the tap. In an alternative embodiment, the draw-off is detected by a drop in system pressure, for example, using a pressure switch. In both variants, the signal indicating the draw-off of warm liquid can also be used to control a pump (for example, the cold water pump) for delivering cold liquid or liquid to be heated.

[0058] In one embodiment, two pumps deliver liquid to a mixing section, with both pumps operating simultaneously. Preferably, one pump delivers heated liquid and the other pump delivers cold liquid to the mixing section. It is designed so that both pumps are generally or always active. This prevents, for example, a situation where only cold or only heated liquid reaches a fitting. In one embodiment, the two pumps are the hot water pump and the cold water pump.

[0059] One embodiment consists of a component for introducing air into the arrangement, and a pump that introduces the air introduced via the component into the container through one of the two openings, so that the liquid exits the container through the other opening. This embodiment allows the liquid container to be emptied or vented.

[0060] In this embodiment, air is introduced into the container for emptying. The component for introducing the air, which is, for example, ambient air from the surroundings of the arrangement or, in particular, the liquid system, functions in one embodiment like a bypass valve. In one of the described embodiments, the component is referred to, for example, as a diverting check valve. The component preferably allows a fluid (here, the air) to flow in only one direction (namely, into the container) and preferably only above a certain pressure differential. The required minimum pressure differential prevents the container from emptying itself due to the hydrostatic vacuum created by the two openings at different heights, which would otherwise cause air to flow into the container via the aforementioned component.Only the described pump, which in one embodiment runs in reverse for this purpose, provides the necessary pressure differential. In one embodiment, this pump is the hot water pump.

[0061] In one embodiment, air is preferably introduced into the container via the opening through which heated liquid is introduced. Thus, in different operating states, heated liquid and air are introduced into the container through one opening, and heated liquid is withdrawn. When air enters the container through one opening, the liquid flows out of the container through the other opening.

[0062] In a further embodiment, the pump is the one that transports the heated liquid away from the heat exchanger or out of the container. This is, for example, the hot water pump.

[0063] According to one embodiment, a pump is provided which is connected to one of the two openings of the container and to the heat exchanger in such a way that the pump draws liquid from the opening and from the heat exchanger. In the suitable embodiment for the second teaching, the pump is connected to the opening of the container and to the heat exchanger in such a way that the pump draws liquid from the opening and from the heat exchanger.

[0064] In a further embodiment, the pump is connected to a hose or pipe that opens onto the heat exchanger. When the pump draws fluid from this hose or pipe, fluid from the reservoir and / or the heat exchanger flows to the pump and thus to the part of the assembly connected to the pump. If a sufficient quantity of fluid is heated by the heat exchanger, the system functions like an instantaneous water heater. If the amount of fluid in the heat exchanger is insufficient to meet the current demand, additional fluid is drawn from the reservoir. In this case, the system functions like a boiler.The direct connection between the pump – which in one configuration can also be called a hot water pump – and the heat exchanger, and the associated flow heater function, allows for the extraction of heated liquid at the start of the heating process. Heating is the process by which the heat exchanger receives thermal energy from the energy unit.

[0065] In one embodiment, the two preceding embodiments are combined by using only one pump for both purposes. According to this embodiment, the pump is designed to pump the liquid from the container opening and the heat exchanger in one direction, and to pump air into the container in another direction. This single pump thus pumps air and liquid in two different directions. In one direction, it pumps heated liquid, for example, to a fitting. In the other direction, it pumps air to the container, thereby emptying it.

[0066] One embodiment consists of two pumps: one pump delivers the fluid to be heated to the heat exchanger, and the other pump is located downstream of the heat exchanger and delivers both air and fluid. In this embodiment, two pumps are present, one upstream and one downstream of the heat exchanger. The pumps thus deliver the fluid to be heated (or cold) and the heated (or hot) fluid, respectively. In one embodiment, the upstream pump is designated as a cold water pump. In another embodiment, the first pump, which in one variant is located upstream of the heat exchanger, is designed to deliver both air and fluid. The downstream pump is designed to deliver not only fluid but also air. This air is the air that escapes from the fluid during the heating process.The downstream pump thus allows the pipe behind the heat exchanger to be vented. In one configuration, the downstream pump is designed as a venting pump. In an alternative configuration, it is the hot water pump.

[0067] A further embodiment provides for the other – i.e., downstream – pump to intermittently pump air and liquid. This pump – preferably the aforementioned venting pump – is therefore not operated continuously, but only at certain time intervals of a predefined duration and at predefined intervals. This contrasts with the upstream pump (for example, the cold water pump), which runs continuously during operation, i.e., during the heating phase of the liquid.

[0068] According to one embodiment, the container has a variable internal volume. In this embodiment, the container is not a rigid component with a fixed internal volume, but rather its internal volume is variable. For example, the container is designed as a bladder surrounded by a supporting structure, such as a grid. The variable internal volume is implemented not only in the container with one opening for the arrangement according to the first teaching, but also, in one embodiment, in the container with two openings for the arrangement according to the first teaching.

[0069] In one embodiment, two pumps are provided, one pumping the fluid through the heat exchanger and the other pumping the fluid from the heat exchanger as well as the fluid from the container, e.g., towards a fitting, with an opening in the container located between the two pumps. The arrangement of the connection points of the two pumps (one after the other) and the arrangement of the container opening (between them) ensures that the container automatically compensates for the difference in the two pump delivery rates. If the upstream pump delivers more fluid than the downstream pump, the heated fluid enters the container through the opening located between the two pumps. Conversely, if the downstream pump delivers more fluid than the upstream pump, heated fluid is drawn from the container through the opening.This clearly demonstrates the dual function of the container's upper opening as both an access point and an outlet. In the first design, this opening is either the one located higher than the other due to gravity, or, in the second design, the only opening directly connected to the components for pumping the liquid. If both pumps have the same delivery rate, the container is effectively bypassed, resulting in the function of an instantaneous water heater. In one embodiment, the upstream pump is the cold water pump. In an alternative or supplementary embodiment, the downstream pump is the hot water pump.

[0070] In one configuration, the upstream pump is located before the heat exchanger, followed by the opening of the tank and then the downstream pump. Thus, in this configuration, the opening is located between the heat exchanger and the downstream pump.

[0071] In one embodiment, when the downstream pump (which is, for example, the hot water pump) starts, the supply of thermal energy to the heat exchanger and the upstream pump (correspondingly, the cold water pump) are also started.

[0072] In one embodiment, at least one of the pumps used in the arrangement has a sufficiently large nominal flow rate, so that only a reduced flow rate is required during normal operation. This reduces noise generation during pumping.

[0073] According to a further embodiment, an additional tank for storing the liquid is provided, and this additional tank is located upstream, downstream, or adjacent to the main tank with respect to filling it with the liquid. In this embodiment, the storage volume of the main tank, or of the entire system, is increased by the additional tank. Depending on the embodiment, the main tank and the additional tank can be connected in series or in parallel. If the main tank has two openings and thus also a drain, the liquid flows through the drain into the additional tank and from there, depending on the embodiment, into a fresh water tank or a grey water tank. In this embodiment, the additional tank is therefore located downstream of the main tank. Alternatively, the main tank and the additional tank are connected by the same pipeline, which, for example, comes from the heat exchanger and leads towards the fitting or the hot water pump.In this case, the main tank and auxiliary tank are thus connected side-by-side or in parallel. In one embodiment, the auxiliary tank is designed as a retrofit option that can be subsequently connected to an already installed main tank. The auxiliary tank is, for example, made of plastic and is connected, for instance, next to or below the main tank. If the auxiliary tank has its own drain, this is preferably equipped with a temperature sensor – analogous to the temperature sensor behind the main tank's drain.

[0074] In one embodiment, the container and / or the auxiliary tank is spatially separated from the other components of the arrangement. For example, the container and / or the auxiliary tank is located inside the vehicle, while the other components are located below the vehicle floor (so-called underfloor). Alternatively, the container is located inside the vehicle and the auxiliary tank is located outside of it.

[0075] One embodiment provides for a descaling device, which is positioned between a first pump that delivers the liquid to be heated to the heat exchanger and a second pump that delivers gas and liquid towards the first pump, such that it adds a descaling agent to the liquid delivered by the second pump. The descaling device, for example, takes in a descaling agent and releases it into the liquid. The second pump is, for example, the venting pump and primarily serves to remove air from the heated liquid. During this process, heated liquid also enters a return path. Since the liquid is heated, the descaling effect is promoted. The return path preferably terminates upstream of an intake port of the first pump, which pumps the liquid to be heated (i.e., cold liquid) to the heat exchanger and through it.The first pump, for example, is the cold water pump. By pumping the liquid containing the descaling agent towards the first pump, the first pump can pump this agent-enriched liquid through the heat exchanger and thus descale it.

[0076] In detail, there are numerous possibilities for designing and further developing the arrangement according to the invention. Reference is made, on the one hand, to the claims subordinate to claim 1, and on the other hand, to the following description of exemplary embodiments in conjunction with the drawing. The drawing shows: Fig. 1 a basic representation of a device for heating a liquid, Fig. 2 an embodiment of the components of a system for dispensing heated water, Fig. 3 the embodiment of the Fig. 2 without reference numerals, but with an indication of functional blocks, Fig. 4 shows an alternative embodiment of part of the system. Fig. 2 Fig. 5 shows a further embodiment of a system according to a second teaching, Fig. 6 shows an additional embodiment of the area around the container, Fig. 7 shows a detailed view of an alternative arrangement of the Fig. 2 and Fig. 8 a detailed view of another alternative arrangement of the Fig. 2 .

[0077] The Fig. 1 The diagram schematically illustrates the basic structure of a device for heating at least one liquid. In one variant, the device also heats air. Overall, the device is thus used for heating fluids. Since the liquid in the described illustrations is water, only water will be referred to in the following text. The device can be connected to other peripheral components, as shown below, to form a complete arrangement (or system) for heating fluids. This arrangement is located, for example, in a caravan, a motorhome, or on a boat. The arrangement is therefore preferably located in or relative to a movable interior space.

[0078] The thermal energy for heating is generated by energy unit 1 through the combustion of a fuel-air mixture and / or by electrical energy and transferred to the liquid by heat exchanger 2. A cold water pump 11 pumps the cold water to be heated – e.g., from a vehicle's fresh water tank or another cold water tank – through heat exchanger 2. The heated water is introduced into a hot water tank 3 and from there flows to a fitting 5. The arrangement of the inlet and outlet is shown here for illustrative purposes only.

[0079] Cold water is also supplied to the fitting 5 via a cold water path 4, for which a cold water path pump 12 is 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 combined in a mixing section 30, so that water tempered to the desired temperature reaches the fitting 5.

[0080] For the processes within the device, a control device 6 is also provided, which, for example, acts on components of the device or the system described below based on measured values. In one variant, the control device 6 controls the energy unit 1 and thereby also the heat exchanger 2 or the heating process. In one variant, this occurs in a time-controlled manner. Alternatively or additionally, the heating process can be started by a user. In another version (not shown), the user triggers the start, for example, via a switch or an app function.

[0081] In the Fig. 2 A system is shown which provides heated domestic hot water at the fitting 5. The system can also be referred to as an arrangement. Although the system shown corresponds to the first teaching of the invention, the description largely also applies to the system according to the second teaching.

[0082] The following describes the system from a cold water tank 10 to the fitting 5. In the application shown here, all inlets and outlets to and from the cold water tank (for example, a fresh water tank of a vehicle or motorhome, etc.) 10 are located below the liquid level. Furthermore, the cold water tank 10 is open to the atmosphere, so it is always at atmospheric pressure.

[0083] The water leaves the cold water tank 10 via three paths: Firstly, it is pumped by a cold water pump 11 into a hot water tank 3; secondly, it flows via a cold water path pump 12, which is, for example, a vehicle pump, directly to the fitting 5 via the cold water path 4 to allow the user to set the desired temperature; and finally, water can flow from the cold water tank 10 into the hot water tank 3 via the drain 13 of the tank 3.

[0084] Water flows into the cold water tank 10, and thus out of the system, via the aforementioned drain 13 from the hot water tank 3. The drain 13 is located in the bottom of the hot water tank 3 and is permanently open. Due to the position of the drain 13 at a low point in the hot water tank 3, the lowest layer of water, which is the coldest layer, flows out first.

[0085] As already indicated, when the hot water pump 20 is activated, water from the cold water tank 10 can also enter this lower area of ​​the hot water tank 3, depending on the flow rates of pumps 11 and 19. For this purpose, a hose or pipe connects the drain 13 to the cold water tank 10, with the hose or pipe opening into the cold water tank 10 below the liquid level.

[0086] A water drain temperature sensor 14 is located between the drain 13 and the cold water tank 10, allowing the measurement of the drained water's temperature. In an alternative embodiment (not shown), the water drain temperature sensor 14 is integrated into the drain 13. Assuming that the coldest water drains and that a target temperature is specified for the hot water (see the following description), the measured temperature indicates the degree to which the tank is filled with water at the desired temperature. Furthermore, the readings from the water drain temperature sensor 14 allow for the control of the heat exchanger 2 and / or the associated energy unit 1.

[0087] First, the path of the water that leads through the hot water tank 3 will be described.

[0088] A cold water temperature sensor 15 detects the temperature of the water that the cold water pump 11 draws from the cold water tank 10. In one embodiment of the system, the cold water temperature sensor 15 enables intelligent control of the cold water pump 11 by feedforward control and / or predictive control. In the embodiment shown here, the cold water pump 11 is self-priming, for example a gear pump, so that it can fill its suction line with water even when it is located above the cold water tank 10, as indicated here.

[0089] In the illustrated embodiment, the cold water pump 11 moves the water in a loop through the hot water tank 3. This loop serves as a cooling section to protect the cold water pump 11 in case it is operated in reverse (see the following description of draining the heat exchanger 2). In an alternative embodiment – ​​not shown here – the loop is omitted, and the cold water pump 11 pumps the water directly to the heat exchanger 2.

[0090] In the heat exchanger 2, the water is heated, for example, by using an electric heating element as the energy unit 1, or by transferring the thermal energy from flue gas or other gases, e.g., hot room air, which have been heated via another heat exchanger (not shown here).

[0091] Downstream of the heat exchanger 2, a hot water temperature sensor 16 is located, which measures the temperature of the heated water. Based on the measured temperature, the flow rate of the cold water pump 11 is controlled (indicated by the dashed line) so that a predetermined target temperature of the heated water is maintained. For example, if the water is too hot, the flow rate is increased. If it is too cold, less water is pumped. In one embodiment, the temperature measurement by the cold water temperature sensor 15 is additionally incorporated into the control system.

[0092] The regulation is implemented by a provision – not shown here, but found, for example, in the Fig. 1 The control device 6 is indicated. In one embodiment, the control device 6 performs further steps: For example, if thermal energy is supplied to the heat exchanger 2, the cold water pump 11 is simultaneously started with a minimum flow rate in order to pump water through the heat exchanger 2 and thus also to the hot water temperature sensor 16.

[0093] In one embodiment, the target temperature of the water to be heated is variable. This makes it possible to reduce limescale deposits in the heat exchanger 2, which may be expected under certain circumstances, by lowering the temperature of the water to be heated and stored.

[0094] To conserve resources, one design provides that heating to the highest temperature only occurs when the full nominal hot water capacity is to be used soon, i.e., when the user opens tap 5. The user can communicate this to the control unit, for example, by pressing a button.

[0095] For the gas dissolved in the water, which forms bubbles when the water is heated, a venting / air release valve 17 is provided, which automatically removes air bubbles from the pipe section downstream of the heat exchanger 2 by establishing a connection with the environment. The venting / air release valve 17 is preferably located – like the connection port of the venting pump 19 – at a high point in the liquid line.

[0096] In one embodiment – ​​not shown here – the air release / venting valve 17 consists of two components, each serving a separate function: there is a component for releasing air (this is implemented, for example, in the manner of an automatic air vent with a float, as is common in heating systems) and there is a component that allows air to enter the system when the cold water pump 11 is running in reverse. The basic structure is as shown in Fig. 2 As indicated: A float is pressed by the water against an opening in a seal at the top. If there is no water, the float falls downwards due to gravity, exposing the opening to the environment. Therefore, air can enter.

[0097] The cold water pump 11 pumps the heated water from the heat exchanger 2 against a bypass valve 18, which in the illustrated embodiment is implemented similarly to a spring-loaded check valve, to a section of pipe where the water either flows into the hot water tank 3 via an inlet 21 or is pumped further towards the fitting 5 by a hot water pump 20. The inlet 21 is located at an upper point in the hot water tank 3, so that the hot water also collects in an upper liquid layer and sinks – due to the inflow of water or the outflow of the lower water layers through the drain 13 – in the direction of gravity or towards the bottom of the hot water tank 3.

[0098] The purpose of the bypass valve 18 arises from the following relationship: The bypass valve 18 is designed to remain closed until a certain differential pressure between the two pipe sides to which it is connected is exceeded. If—as shown here—the hot water tank 3 is located higher than the cold water tank 10, a slight negative pressure results along the hot water tank 3, starting from the height of the water column. If the bypass valve 18 were to open due to this small pressure difference, the hot water tank 3 would be filled with air via the vent valve 17 and, in particular, via its venting function. Therefore, the bypass valve 18 is designed as follows:In the case shown here, the spring is so strong that the bypass valve 18 remains closed even when the hot water pump 20 is running at full load and thus creates a greater vacuum in the hot water tank 3 than would be achieved by the water column alone. Only the delivery pressure of the cold water pump 11 is able to overcome the spring force, or more generally, to open the bypass valve 18 and deliver water to the hot water tank 3.

[0099] The overflow valve 18 causes a pressure drop in the pumped water, allowing further gas to escape from the water in the form of bubbles. This gas is discharged via the venting pump 19. The pipe sections between the overflow valve 18, the hot water pump 20, and the outlet 21 are preferably designed to form a high point, towards which the gas automatically flows as the inlet / outlet pipes rise steadily. The venting pump 19 preferably extracts the gas at this high point.

[0100] The venting pump 19 also functions as a check valve, so that in one embodiment (not shown here) the venting pump 19 consists of two components (one for the pumping function and one for the check valve function). This additional function of the venting pump 19 is necessary so that the hot water pump 20 only draws in heated water and not water or gas that has been discharged via the venting pump 19. In the exemplary embodiment, the venting pump 19 is designed as a diaphragm pump, which also fulfills the function of a check valve.

[0101] In one embodiment, the control device 6 automatically activates the venting pump 19 while thermal energy is supplied to the heat exchanger 2. In another embodiment, the venting pump 19 is operated intermittently to improve gas removal while simultaneously minimizing the amount of hot water drawn from the hot water tank 3.

[0102] Since the process of pumping out gas usually involves pumping out water as well, the return line 31, which originates from the venting pump 19, terminates before the cold water pump 11. The gas is then discharged through the air release valve 17. The water pumped out by the venting pump 19 mixes with the water from the cold water tank 10 in the suction line of the cold water pump 11 and is then passed back through the heat exchanger 2. Thus, no thermal energy is lost by removing the air.

[0103] The section where the water recirculated by the venting pump 19 is fed into the cold water pump 11 is designed such that the water from the venting pump 19 enters the suction line from the cold water tank 10, but does not flow into the tank itself. In this configuration, the recirculated water is thus moved back towards the heat exchanger 2 by the cold water pump 11. The venting pump 19 is operated intermittently. This has the advantage of creating a reservoir of warm fluid between the cold water pump 11 and the cold water tank 10.

[0104] In one embodiment, the venting pump 19 is operated continuously. In an alternative embodiment, the venting pump 19 is operated intermittently, i.e., with interruptions. This offers the advantage of promoting the removal of air without discharging too much heated water.

[0105] The hot water pump 20 conveys the water towards the fitting 5 and, if necessary, draws water from the hot water tank 3 via the inlet 21. Depending on the flow rate of the cold water pump 11 and the hot water pump 20, the system behaves like a boiler (water is drawn from the hot water tank 3) or an instantaneous water heater (heated water flows directly to the fitting 5). If water is drawn from the hot water tank 3 via the inlet 21 at the top, the vacuum created by the hot water pump 20 draws water from below through the drain 13 in the cold water tank 10. This ensures that there is no air in the hot water tank 3.

[0106] Downstream of the hot water pump 20 are a branching check valve 22 – which is also spring-loaded in this configuration – and a first mixing path check valve 23. The branching check valve 22 is described below with reference to the emptying of the hot water tank 3.

[0107] The first mixing-path check valve 23 ensures that the heated water flows only towards a mixing section 30, which leads to the fitting 5. Furthermore, it ensures that the cold water path pump 12, regardless of its outlet pressure, cannot push cold water backwards through the hot water pump 20 into the hot water tank 3. This is relevant, for example, in the case—shown here—where the hot water pump is designed as a gear pump without a check valve function. It also ensures that the pressure in the pipe system to the fitting 5 is maintained when no water is being drawn from it. This is particularly important when the cold water path pump 12 is controlled by a pressure switch 26 (as in the illustrated embodiment).

[0108] In an alternative embodiment – ​​not shown – a pressure reducer is provided – preferably directly – after the cold water path pump 12, which lowers the outlet pressure of the cold water path pump 12 to a similar pressure level as that of the hot water pump 20. This prevents the two pumps 12 and 20 from interfering with each other during their operation.

[0109] To understand the mixing section 30, the cold water path 4 will now be described. The cold water path pump 12 pumps the water from the cold water tank 10 towards the fitting 5. The cold water flows directly to the fitting 5 and also, via a branch, to the mixing section 30. A second mixing path check valve 24 is located in the branch line from the cold water path 4 to the mixing section 30, which allows the cold water to flow only in this direction to the mixing section 30. This ensures that, at low outlet pressure, no hot water is directed from the cold water path pump 12 towards the cold water tank 10 or the side of the cold water connection of the mixing fitting 5. This is particularly important if the cold water path pump 12 allows backflow of the pumped medium, as is the case, for example, with centrifugal or submersible pumps.

[0110] If the two pumps 12 and 20 are well matched with respect to their flow rates and pressures, the two mixing path check valves 23 and 24 can be omitted in a further embodiment (not shown). This applies in particular if the pumps 12 and 20 are not controlled by a pressure switch 26, but for example by an electrical switch integrated in the mixing valve 5 (not shown).

[0111] The mixing section 30 thus receives water heated to a predetermined setpoint temperature and cold water from the cold water tank 10. The temperature of the mixed water is measured by a mixing temperature sensor 25. Based on the measured temperature and a predetermined setpoint mixing temperature, the flow rate of the hot water pump 20 is regulated – in the illustrated configuration. This is done to ensure that the predetermined setpoint mixing temperature is reached. This is therefore the maximum temperature that the water can have when it exits the fitting 5. This provides scalding protection for the user.

[0112] In a supplementary or alternative embodiment, the flow rate of the cold water path pump 12, which is, for example, a vehicle pump, is controlled: When the control of both pumps 12, 20 is combined, the control of the cold water path pump 12 offers the advantage in cases where the hot water pump 20 is approaching its performance limit or where the hot water tank 3 contains only somewhat cooled or not sufficiently heated water, and where the setpoint for the mixed temperature is undershot. Therefore, for example, the water flow rate at the tap 5 is reduced to maintain a constant water temperature.

[0113] In one variant, the user can specify the target mixing temperature, which is then compared to the measured values ​​of the mixing temperature sensor 25 for controlling the hot water pump 20. If the user then sets the tap 5 to hot water only, they will receive water at the desired target mixing temperature.

[0114] In an alternative variant – not shown – the direct connection between the cold water tank 10 and the fitting 5 is omitted. Therefore, no manual mixing by the user takes place. This is replaced by the user specifying the desired mixing temperature, which is then controlled based on the temperature measured by the mixing temperature sensor 25. For example, if the user wants the water to be at a temperature of 38 °C, the hot water pump 20 is controlled to mix the appropriate amount of hot water with the cold water pumped by the cold water path pump 20.

[0115] A pressure switch 26 is also located in the cold water path 4. This switch detects the actuation of the valve 5 and the resulting pressure drop. Based on this, the hot water pump 20 and the cold water path pump 12 are started, so that water is available at the valve 5. Conversely, if 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 centrifugal pump), which is switched on, for example, by a microswitch on the valve 5. This microswitch simultaneously switches the hot water pump 20 on (or off). If the cold water path pump 12 is designed as a pressure pump (e.g., in the form of a diaphragm pump), the pressure switch 26 can be part of the pump 12.

[0116] The relevant temperatures in the system are, for example, as follows: The cold water has a temperature of 13 °C. The temperature of the heated water is 80 °C, thus preventing germs in the water, such as Legionella. The temperature of the mixture of heated and cold water is 50 °C. If the user mixes the water at tap 5, the temperature can, in principle, range between 13 °C and 50 °C for these example values.

[0117] The following describes how the system allows the hot water tank 3 and the heat exchanger 2 to be emptied of water. For this purpose, the cold water pump 11 and the hot water pump 20 are designed to pump media in two directions and also two different media (water as a liquid and air as a gas). They are therefore self-priming. In one embodiment, the pumps 11 and 20 are designed as gear pumps (as shown). So far, the application of the forward direction has been described.

[0118] To drain the heat exchanger 2 of water, the cold water pump 11 is reversed in its pumping direction. The bypass valve 18, located between the heat exchanger 2 and the inlet 21 of the hot water tank 3 or the hot water pump 20, automatically closes the line. Therefore, no water can flow back from this side towards the fitting 5.

[0119] If the cold water pump 11 pumps in reverse, air from the environment flows through the air release valve 17 into the pipe and, in particular, through the pipe section that extends through the heat exchanger 2. The pipe is thus emptied and the heat exchanger 2 cannot heat any liquid.

[0120] Draining is relevant, for example, if the heat exchanger 2 is intended to heat not only liquid but also ambient air, and especially if a pure air mode is planned in which only ambient air, and no liquid, is heated. Furthermore, in the air mode, thermal energy is supplied to and transferred from the heat exchanger 2, which can result in a temperature above the boiling point of water. The purpose of draining the line in the area of ​​the heat exchanger 2 is to prevent noise or pressure surges when liquid evaporates. Therefore, the ambient air, which is generally cold and enters through the vent valve 17, carries away any water vapor produced when heat is transferred to the heat exchanger 2 before the aforementioned disruptive phenomena occur.

[0121] In this operating mode, air and water vapor are pumped into the cold water tank 10 to empty heat exchanger 2, where they can escape back into the environment.

[0122] To reduce the risk of damage to the cold water pump 11 from such a hot steam / air mixture, in one embodiment it can be guided in a loop through the hot water tank 3 and cooled before passing through the cold water pump 11 (as shown). The loop thus serves as a cooling section to protect the cold water pump 11.

[0123] For example, if the hot water tank 3 needs to be emptied for the cold season, for a longer period of non-use, or for cleaning purposes, the hot water pump 20 is operated in reverse. In addition, the cold water pump 11 does not pump any water, and the venting pump 19 is also inactive.

[0124] When the hot water pump 20 pumps the water away from the fitting 5 towards the inlet 21 of the hot water tank 3, the first mixing path check valve 23 closes and air from the environment around the arrangement can enter the line via the branching check valve 22 and be pumped by the hot water pump 20 towards the hot water tank 3.

[0125] The diverting check valve 22 is designed such that it does not open due to the slight negative pressure that arises in the hot water tank 3 from the height difference between the drain 13 or the cold water tank 10 and the inlet 21, but only when a sufficiently large negative pressure is generated on the side of the check valve 22 by the hot water pump 20 when operating in reverse. In one embodiment, the check valve 22 is designed as a spring-loaded check valve or as a bypass valve.

[0126] The water flows out of the bottom of the hot water tank 3 through the drain 13 and is displaced by the ambient air pumped into the tank 3 from above, until the hot water tank 3 is empty.

[0127] The heat exchanger 2 is filled by the self-priming cold water pump 11, which pumps liquid to the heat exchanger 2, displacing air and allowing it to escape to the environment via the vent valve 17. For this purpose, the pipe section between the heat exchanger 2 and the bypass valve 18 is preferably designed and arranged such that the vent valve 17 is located at a high point between them.

[0128] Based on the preceding description, two methods for filling the hot water tank 3 are described. This is done via the venting pump 19, eliminating the need for the cold water pump 11. Alternatively or additionally, filling is carried out by the hot water pump 20, which is operated while the valve 5 is open and the cold water path pump 12 is not running. In both cases, water is drawn from the cold water tank 10 into the hot water tank 3 via the drain 13.

[0129] The hot water tank 3 has two openings: an upper one 21 and a lower one 13. In the description, the upper opening 21 is referred to as the inlet, insofar as the heated water enters the tank 3 through the inlet 21. However, this opening also serves as an outlet, as the hot water pump 20 can draw the heated water from it. The lower opening 13 is referred to as the outlet, insofar as water flows out through it when hot water or air enters the tank 3 via the inlet 21. However, this opening 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 tank 3 via the inlet 21, which in this case functions as an outlet. Thus, both openings 21 and 13 could also be described as inlet / outlet openings.

[0130] Depending on its configuration, the system described here comprises the components of a water heating device and corresponding peripheral components. In one configuration, the system (alternative designation: arrangement) consists of such a device and the cold water tank 10, with the connection between the two being established via a corresponding number of lines (i.e., hoses or pipes). In an alternative configuration, the device does not include the fitting 5, so that the device is connected to the cold water tank 10 and the fitting 5 as external components. In another alternative configuration, the cold water path pump 12 is not part of the device but is, for example, a vehicle pump such as those commonly found in motorhomes. Therefore, in this configuration, the device includes corresponding interfaces for controlling the cold water path pump 12 or for detecting its operating status.Accordingly, fitting 5 can also be part of the periphery of the device here.

[0131] It is indicated in the Fig. 2 Furthermore, a descaling device 7 is located in the return line 31 between the venting pump 19 and the cold water pump 11. This is, for example, a device into which a descaling agent can be introduced and which adds the descaling agent to the returned liquid.

[0132] The following describes a descaling process characterized by minimizing the amount of descaling agent entering the cold water tank 10. This process reliably descales pumps 11, 19, 20 and heat exchanger 2.

[0133] The venting pump 19 and the cold water pump 11 are in operation, with the energy unit 1 supplying only a small amount of thermal energy to the heat exchanger 2. The cold water pump 11 is set to a flow rate such that the cold water temperature sensor 15 measures only the temperature of the water from the cold water tank 10 and not the recirculated water. As a result, no recirculated water containing descaling agent flows into the cold water tank 10. Furthermore, the water containing the descaling agent is slightly warmed, which accelerates the descaling process.

[0134] The cold water pump 11 is operated in such a way that it pumps more water than the vent pump 19, so that water also reaches the tank 3. To prevent the descaling agent from entering the cold water tank 10 via the drain 13, the hot water pump 20 is in operation when the valve 5 is open. Additionally, the cold water path pump 12, which is, for example, a vehicle pump, is preferably not in operation.

[0135] Based on the temperature measurements of the mixing temperature sensor 25, the control device 6 reverses the direction of operation compared to normal operation by setting a higher flow rate for the hot water pump 20 when the temperature measured in the mixing section 30 is above the setpoint (in normal operation, the flow rate would be reduced). In addition, a setpoint is set that is slightly lower than the measured value of the hot water temperature sensor 16. This causes the hot water pump 20 to increase its flow rate by increasing its speed. As a result, it pumps a larger quantity of water than the amount of hot water entering the tank 3. This draws fresh water from the cold water tank 10 via the tank 3. The drain 13 of the tank 3 thus allows filling from the downstream cold water tank 10. This prevents descaling agents from entering the cold water tank 10.

[0136] For descaling the container 3, it is provided in one operating mode that the hot water pump 20 is not operated or only with low delivery capacity, so that the water containing descaling agent and heated enters the container 3.

[0137] In one variant - not shown - there are sieves at various points in the piping system which collect limescale fragments before they render components such as valves or pumps unusable.

[0138] If the pumps used (hot water pump 20 and cold water pump 11) are gear pumps, their ability to pump air can be improved by pumping a small amount of water along with the air. The water acts as a sealant, reducing internal leaks and backflow of air. This increases the volume of air pumped and the delivery pressure. In turn, this allows the pumps to be smaller and / or operate more quietly, as a sufficient volume of air is pumped. This is in contrast, for example, to a diaphragm pump, such as the type that can be used in one version of the venting pump 19.

[0139] Let us first consider the hot water pump 20: The arrangement – ​​not shown here – is such that there is a gradient in the liquid line before the pump 20's inlet. When the hot water pump 20 pumps backwards, and thus towards the container 3, it initially displaces water, which is pushed upwards. The line, which in normal operation is the supply line to the pump 20 and which is located above the pump 20 against the Earth's gravity, will typically contain a few drops of water, which flow back into the pump 20 when it is briefly switched off. Then, the "sealing agent" is present again, and it can pump air more effectively. Therefore, the hot water pump 20 is operated intermittently for pumping air.

[0140] In one embodiment (not shown), a pipe thickening is located above the hot water pump 20, ensuring that when the pump 20 is not running, sufficient water always flows back or downwards into the pump 20. The thickening is large enough that the pumped air does not completely carry away the water it contains.

[0141] Consider further the application to the cold water pump 11: A design is provided for the cold water pump 11 which is described in the Fig. 7 The return line, into which the venting pump 19 pumps air and water, terminates at a point located above the intake port of the cold water pump 11. Water from the cold water tank 10, whose temperature is measured by the cold water temperature sensor 15, also enters this intake port.

[0142] The cold water pump 11 draws water from the cold water tank 10 itself and vents the heat exchanger 2, which may need to be done every time before water is heated: If the heat exchanger 2 has been previously vented, air passes through the cold water pump 11 into the cold water tank 10.

[0143] Alternatively, according to the design of the Fig. 7 The following is provided: The venting pump 19 pushes small amounts of water at intervals through the return line to the intake port of the cold water pump 11. This ensures that the pump 11 always has enough "sealing fluid" to draw water efficiently from the cold water tank 10. The upward-facing intake port of the cold water pump 11 facilitates water flow into it.

[0144] In the arrangement of the Fig. 2 Three lines lead to the cold water tank 10: one line for drawing water to be heated, one line for drawing cold water for the fitting 5 or the mixing section 30, and one line through which water from the drain 13 of the container 3 flows into the cold water tank 10. To protect these lines from freezing, they are arranged side by side in a configuration (not shown here) that forms a common hose with three channels. The ends of the channels in the cold water tank 10 are sufficiently separated to prevent water from flowing directly from one channel into another.

[0145] This design with the parallel pipes allows for an elegant method of heating the pipes to prevent freezing: If the system is not in operation, or at least if no hot water is being produced, the venting pump 19 is occasionally activated to supply a small amount of warm water via the return line to the hose connecting the cold water tank 10 to the cold water pump 11, which is inactive during these times. This warm water then also heats the adjacent hoses or channels. This process is temperature- and / or time-controlled. This prevents the hose from freezing.

[0146] In the Fig. 3 is the system of Fig. 2 The individual functional units are shown again below to describe them separately. For the sake of clarity, the individual reference symbols are omitted; instead, the focus is on the... Fig. 2 The description also applies accordingly to the arrangement according to the second teaching, as exemplified in the Fig. 5 is shown.

[0147] The system includes a functional block A, in which the control of the target temperature of the heated water takes place.

[0148] For this purpose, the temperature of the water heated after contact with the heat exchanger is measured, and based on this measurement – ​​as an example here – the cold water pump, which transports the water to be heated through the heat exchanger, is regulated accordingly. The pump's delivery rate is thus continuously regulated so that water at the desired temperature reaches the inlet of the hot water tank or further towards the faucet. The heated water flowing into the hot water tank displaces the water already present, particularly the cold water. (As will be explained below, in the arrangement according to the second teaching of the invention, this causes the tank 3 to expand.) The cold water flows out of the hot water tank, and the hot water tank fills with water at the desired temperature, which can also be pumped to the faucet.As already mentioned, the pumping function can be performed by the cold water pump, the venting pump, or the hot water pump.

[0149] Functional block B serves to remove dissolved air released when the water is heated. It can also remove air present, for example, in an empty hot water tank or heat exchanger before initial filling.

[0150] This is intended to prevent air from accumulating in the hot water tank, which would disrupt the operation of the hot water pump and also lead to air being mixed in at the tap. Air in the tank would also negatively impact its usable heat capacity.

[0151] The air that is released from the water during heating escapes from the pipe system via a vent valve. If any air remains in the water downstream after passing through the vent valve, a pressure drop across a bypass valve causes it to escape and be removed by a vent pump. The air, and any water pumped along with it, is reintroduced into the pipe system for heating the water before reaching the heat exchanger. Therefore, the air—now undissolved—enters the vent valve again and is released into the environment. The thermal energy of the water is not lost in this process, as the water is recirculated.

[0152] For the initial filling of the hot water tank, operation of the cold water pump is not necessary; in this case, the air extracted via the venting pump is discharged into the fresh water tank.

[0153] Functional block C maintains a constant water output temperature that does not exceed a maximum limit. This block C is found in the arrangements described in both theories.

[0154] In mixing block C, the heated and cold water are mixed in such a way that the water dispensed from the tap cannot exceed a maximum temperature. This prevents scalding and also provides a comfort feature. The maximum temperature is lower than the set temperature generated by the heating block A.

[0155] For this purpose, a mixing section is provided, into which heated water is introduced via a hot water pump and cold water via a separate pump. A mixing temperature sensor detects the temperature in the mixing section, and the flow rate of the heated water is regulated based on this measurement. In one embodiment, the mixing block C allows the user to set the temperature at which the water should exit the fitting, such as a faucet or shower head. This eliminates the need for the user to manually adjust the temperature; they only need to enter a setpoint. In another embodiment, the flow rate of the cold water is regulated either alternatively or additionally.

[0156] In one embodiment, the mixing block C is a separate device that is connected to other components in the periphery via appropriate interfaces - particularly with regard to the guidance of liquid.

[0157] Functional block D is used to switch on mixing block C.

[0158] For example, if a pressure switch or a microswitch integrated into the fitting detects that the fitting is open and water is flowing, the pumps for the cold and heated water are activated. This then triggers the mixing process in the mixing block C. The heated water comes directly from the heat exchanger and / or is drawn from the hot water tank. Therefore, water is immediately available to the user after the fitting is opened.

[0159] The functional container drain block E serves to drain the hot water tank. This applies to the arrangement according to the first teaching. The draining of the tank 3 in an arrangement according to the second teaching is described below.

[0160] For draining, the pump that delivers the heated water to the faucet is run in reverse. This opens a check valve or bypass valve connected to the ambient air. The check valve allows air to flow in only one direction and only when a certain pressure differential is present. The pump thus first draws water from the pipe and then air to the inlet of the hot water tank. The pumping action also creates the aforementioned pressure differential that allows air to enter through the check valve. Under normal operation, the pump draws water from the hot water tank through this inlet. Since the pump in heating unit A, which normally delivers cold and then heated water to the hot water tank, is switched off, no new water flows from there towards the inlet. Additionally, the venting pump is switched off.The water flows out of the hot water tank through the drain, and the reverse-running pump empties the hot water tank.

[0161] It may be necessary to prevent the water from being heated by the heat exchanger. This is the case, for example, if the heat exchanger is intended to heat air, not water, in an operating mode. Any remaining water in the pipe would evaporate and cause noise. Therefore, the functional heat exchanger drain block F is present. Block F can be implemented in both designs.

[0162] In this functional block F, the pump that circulates the water to be heated operates in reverse, thus drawing the remaining water back from the heat exchanger area. The air release / venting valve, already described in connection with the venting block B, assists in this process and acts as a venting valve in this operating mode. Air from the surrounding environment enters the line and pushes the remaining water towards the reverse-running pump.

[0163] Another functional block – not shown for clarity – serves to descale pumps 11, 19 and 20 as well as heat exchanger 2. Reference is made to the description above. Fig. 2 .

[0164] Fig. 4 Figure 1 shows part of a variant of the system described above. In this version, the preheated water from the hot water tank 3 flows from the drain 13 into a grey water tank 27, which is preceded by a grey water tank check valve 29. The valve 29 only allows flow towards the grey water tank 27. The cold water flows from the cold water tank 10 via a cold water tank check valve 28 and through the drain 13, which in this case serves as the inlet, into the lower part of the hot water tank 3. The outflow of water into the grey water tank 27 and the inflow of water from the cold water tank 10 are coordinated so that no air enters the hot water tank 3. This variant prevents heated water from entering the cold water tank 10.

[0165] In the Fig. 5 is an alternative to the variant of Fig. 2 or Fig. 3 This is an example of the second teaching. Only the differences will be discussed below. The preceding explanations apply to the components not discussed here.

[0166] The hot water tank 3 does not have a fixed, but rather a variable liquid volume. This is indicated here by the bladder. Depending on the fill level, the tank 3 can expand. Around the bladder, which represents the actual tank 3, there is, for example, a support structure, such as a grid.

[0167] Furthermore, container 3 has only one opening 21, which can be located at any position, and here, for example, at the top. Container 3 is designed so that no air collects in it when filled with liquid. For this purpose, container 3 is, for example, designed to be smooth and free of protrusions or folds, etc.

[0168] In particular, above the opening 21, the air is extracted at a high point by the venting pump 19 before it can enter the container 3.

[0169] Both teachings agree that container 3 is completely filled with liquid during the heating operation of the device or arrangement and that it contains no air. This is achieved here, for example, by container 3 contracting when liquid is drawn off, instead of cold water flowing in from the cold water tank.

[0170] In arranging the Fig. 5 Accordingly, no branching check valve 22 is required, which is in the arrangement of the Fig. 2 This had previously allowed the container with a fixed internal volume to be emptied via the hot water pump 20. Since this method of emptying the container 3 is no longer necessary, it is sufficient if the hot water pump 20 only pumps towards the fitting 5. Therefore, the pump 20 could, for example, also be a diaphragm pump.

[0171] By not having a second, permanently open opening in container 3, as in the variant of Fig. 2 When the cold water pump 11 is activated, the operating behavior of the arrangement changes: If the tank 3 has reached its maximum internal volume, no further water can be pumped in by the cold water pump 11. Therefore, either water must be drawn off via the hot water pump 20 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.

[0172] To empty container 3 – for example, the bladder – completely and in a targeted manner, the venting pump 19 can be used. The cold water pump 11 must be switched off for this to work. The venting pump 19 empties container 3 and pumps the water back into the fresh water tank 10 via the suction hose of pump 11.

[0173] A fundamental difference between the two arrangements lies in the fact that in the arrangement according to the second doctrine of Fig. 5 In the event that the water in 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 of the Fig. 2 The two openings in the container allow immediate heating of water via heat exchanger 2.

[0174] The Fig. 6 This shows an embodiment according to the first teaching of the invention. Its application to the second teaching is obvious.

[0175] The diagram shows part of the arrangement around container 3. Visible – not only graphically, but also in relation to the actual geometry – above container 3 are the overflow valve 18, the venting pump 19, and the hot water pump 20. Downstream of the outlet 13 of container 3, in the direction of flow, is an auxiliary tank 3'. The auxiliary tank 3' is positioned relative to container 3 in such a way that the hydrostatic pressure in container 3 remains unchanged. The auxiliary tank 3' thus only increases the capacity. Therefore, container 3 and auxiliary tank 3' could also be considered a single unit for holding the liquid. An outlet opening 13' of the auxiliary tank 3' is connected to the fresh water tank 10. Thus, in this configuration, container 3 is indirectly connected to the fresh water tank 10.

[0176] The variant of the arrangement of Fig. 6 This can also be applied to the arrangement that is in the Fig. 5 As shown. However, the auxiliary tank 3' does not have an outlet opening 13'.

[0177] In addition to the water drain temperature sensor 14, the auxiliary tank 3' also has an auxiliary tank temperature sensor 14', the measured values ​​of which are used to control the arrangement.

[0178] In the Fig. 8 The connection of the arrangement to a fixed water connection 40 is shown. For the supply of water to the cold water tank 10, a float valve 41 is provided in the illustrated embodiment, which ensures automatic refilling.

[0179] Additionally, the arrangement is designed so that it is possible to forego the operation of the cold water path pump 12. This is desirable, for example, if it is a vehicle pump designed as a pressure pump to reduce noise.

[0180] 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 an additional connection upstream of valve 41 into the cold water path 4. This connection opens downstream behind the cold water path pump 12. A first check valve is located after the fixed water connection 40 and before the branch to the cold water path 4, preventing water from being pumped back into the water network. A second check valve is located downstream of the cold water path pump 12 and upstream of the connection from the fixed water connection 40, preventing the cold water tank 10 from being filled backwards via the cold water path pump 12.

[0181] 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 circulating water only through the float valve 41 when the water level in the cold water tank 10 is low, instead of building up pressure at the fitting 5.

Claims

1. An arrangement for heating a liquid, comprising an energy unit (1), a heat exchanger (2), a container (3), and a pump (20), wherein the energy unit (1) supplies the heat exchanger (2) with thermal energy, wherein the heat exchanger (2) transfers the thermal energy to the liquid, wherein the container (3) receives the liquid, wherein the container (3) has an opening (21), wherein the pump (20) is connected to the opening (21) of the container (3) and to the heat exchanger (2) such that the pump (20) delivers liquid from the opening (21) and / or from the heat exchanger (2), characterized in that an additional pump (11) is present, wherein the additional pump (11) transports liquid to be heated through the heat exchanger (2), wherein the opening (21) of the container (3) is arranged between the heat exchanger (2) and the pump (20), wherein an aeration / ventilation valve (17) and a return line (31) are present, wherein the aeration / ventilation valve (17) allows air to be discharged from the arrangement, wherein a ventilation pump (19) is present for discharging air and liquid through the return line (31), and wherein the return line (31) opens upstream of the aeration / ventilation valve (17) and upstream of the additional pump (11).

2. The arrangement according to claim 1, wherein a temperature sensor (16) is present for measuring a temperature of the liquid heated by the heat exchanger (2), and wherein the arrangement comprises a control device (6), which receives measured values of the temperature sensor (16) and uses them for controlling the additional pump (11).

3. The arrangement according to either of claims 1 and 2, wherein the arrangement comprises a mixing section (30), wherein the pump (20) delivers heated liquid to the mixing section (30), wherein a cold water path (4) is present which opens onto the mixing section (30), wherein a mixed temperature sensor (25) is present for measuring a temperature of the liquid in the mixing section (30), and wherein a control device (6) controls the pump (20) and / or a cold water path pump (12) for delivering the liquid in the cold water path (4) on the basis of measured values of the mixed temperature sensor (25) and a predetermined temperature range.

4. The arrangement according to any of claims 1 to 3, wherein a component (18) is located between the aeration / ventilation valve (17) and the ventilation pump (19) and opens when a predefined pressure difference is exceeded, in order that the liquid can flow in the direction of the ventilation pump (19).

5. The arrangement according to any of claims 1 to 4, wherein the additional pump (11) delivers air through the heat exchanger (2) in one delivery direction and delivers liquid through the heat exchanger (2) in another delivery direction.

6. The arrangement according to any of claims 1 to 5, wherein a descaling device (7) is present, and wherein the descaling device (7) is arranged along the return line (31) so as to add a descaling agent to the liquid delivered by the ventilation pump (19).