DE102011016198A1 - Water-heater - Google Patents

Abstract

The invention relates to a water heater (1) and a method for operating a water heater with a heat exchanger (2) for heating a flowing liquid, which has a service water inlet (21) for connecting a cold water line (31) and a service water outlet (22) for connecting a hot water line (32), wherein a controller is provided for regulating an outside temperature of the dispensed liquid. A temperature sensor (6) is arranged at the domestic water inlet (21) in order to enable the water heater to operate even when the cold water line (31) is connected to the domestic water outlet (22) and the hot water line (32) is connected to the domestic water inlet (21). The actual temperature of the liquid is regulated to a predetermined target temperature depending on the direction of flow through the heat exchanger (2).

Description

The invention relates to a water heater with a heat exchanger for heating a continuous liquid, which has a service water inlet for connection of a cold water pipe and a hot water outlet for connection of a hot water pipe, wherein a controller for controlling or regulating a temperature of the liquid is provided.

Furthermore, the invention relates to a method for operating such a flow heater with a heat exchanger for heating a flowing liquid.

Instantaneous water heaters are used, for example, for heating domestic water in households. Water is supplied to the water heater via a cold water line, heated within the flow heater by means of a heat exchanger and discharged via a hot water pipe. The heat exchanger can either be heated directly or via a secondary circuit. The term service water is to be understood generally and includes, for example, drinking water.

For proper operation of a water heater, it is necessary that the hot water pipe and the cold water pipe are correctly connected, so that the cold water pipe at the service water inlet and the hot water pipe are connected to the hot water outlet. Typically, then, a control of the heat input to the heat exchanger in response to a dispensed amount, which is detected by means of a flow sensor. However, a flow sensor works satisfactorily only if the desired direction of flow through the heat exchanger is maintained, so the cold water pipe at the service water inlet and the hot water pipe are connected to the hot water outlet. If the connections are interchanged, incorrect measurements of the dispensed liquid can occur. It is also possible that the flow sensor emits no signal at all, so it can not be determined whether liquid is dispensed.

In conventional instantaneous water heaters a correct connection of the cold water pipe at the hot water outlet and the hot water pipe at the domestic water inlet is required for proper operation. A release of a heated liquid, in particular hot water, is usually not possible with exchanged connections.

The invention is based on the object to enable operation of the water heater even with a permutation of the connections.

According to the invention this object is achieved by a water heater having the features of claim 1. Advantageous developments can be found in the dependent claims.

By arranging a temperature sensor at the service water inlet, regardless of the direction of flow of the liquid through the heat exchanger, ie regardless of whether the cold water pipe at the service water outlet or service water inlet and the hot water pipe is arranged correspondingly at the service water input or hot water outlet, heated liquid can be dispensed. A temperature change at the service water inlet suggests that liquid is dispensed or tapped. Such water delivery is also referred to as tapping. If the temperature sensor indicates an increasing temperature at the domestic water inlet, this indicates that the hot water pipe is connected to the domestic water inlet, ie the heat exchanger is passed through in a flow direction from the hot water outlet to the domestic water inlet. Thus, a control or regulation of the temperature of the dispensed liquid or the heat exchanger in dependence on the measured at the service water inlet actual temperature. A normal operation, which is set in a passage direction of the hot water inlet to the hot water outlet, can be issued, so that the water heater is operated in a fault mode.

Usually, a temperature sensor is arranged at the service water outlet. Such a temperature sensor at the hot water outlet is used with correct connection of hot water pipe and cold water pipe, so a direction of passage from the hot water inlet to the hot water outlet, for detecting the actual temperature in the hot water pipe and thus to control or regulate the heat transferred through the heat exchanger to the liquid heat. By the temperature sensor at the hot water outlet can thereby further improve error detection. A comparison of the temperature at the service water input and service water output provides relatively reliable information about whether the cold water pipe is connected to the service water inlet or the hot water outlet. If the temperature at the service water input exceeds the temperature at the dhw output, the connections are reversed so that the instantaneous water heater should be operated in fault mode.

Preferably, a flow sensor is arranged at the service water inlet and / or at the service water outlet. Such a flow sensor is common in many conventional instantaneous water heaters present, with the aid of the flow sensor, a discharge amount is determined, which serves to control the heat transferred through the heat exchanger to the liquid amount of heat. Such a flow sensor is usually reliable only in one direction of passage, according to the invention, the directional dependence of the flow sensor can also be used to detect whether the cold water pipe is correctly connected to the service water inlet and the hot water pipe correctly at the hot water outlet. If, despite a temperature increase at the service water inlet of the flow sensor no signal, ie signal no discharge, there are clearly reversed connections, so that the water heater must be operated in error mode, in which the control of the discharged liquid takes place in dependence on the temperature at the service water inlet.

In a preferred embodiment, the heat exchanger on a secondary circuit with a pump and a heat source, which are controllable by the controller. By means of the secondary circuit and the pump, heat generated by the heat source is brought into the heat exchanger and transferred from there to the liquid, so that it can be discharged heated. The heat source may have different configurations, for example, be designed as a gas or oil burner or as an electric heating element. It is also conceivable to form the secondary circuit, for example, as part of a central heating system.

• 0: Überprüfung notwendig,
• 1: Normalbetrieb,
• 2: Fehlerbetrieb,

wobei ein Betrieb des Durchlauferhitzers in Abhängigkeit vom hinterlegten Zustand erfolgt. Zur Speicherung des jeweiligen Zustandes ist dabei ein Byte erforderlich, was gegenüber einer Speicherung in einem einfachen Bit den Vorteil hat, dass es weniger fehleranfällig ist. Vor der ersten Initialisierung bzw. dem ersten Hochfahren des Durchlauferhitzers ist dabei im Speicher hinterlegt, dass eine Überprüfung notwendig ist. Dadurch wird sichergestellt, dass nach jedem Neuanschluss eine Überprüfung erfolgt, ob die Warmwasserleitung korrekt am Brauchwasserausgang und die Kaltwasserleitung korrekt am Brauchwassereingang angeschlossen ist. Wird dies bejaht, wird der Durchlauferhitzer im Normalbetrieb betrieben und dieser Zustand im Speicher hinterlegt. Im Normalbetrieb können durch einen Benutzer verschiedene Einstellungen vorgenommen werden, beispielsweise der Durchlauferhitzer in einem Eco-Modus oder einem Komfort-Modus betrieben werden. Im Eco-Modus wird zur Energieeinsparung eine weitgehende Abkühlung des Wärmetauschers zugelassen, wenn keine Flüssigkeit gezapft wird. Im Fehlerbetrieb, also wenn die Warmwasserleitung am Brauchwassereingang und die Kaltwasserleitung am Brauchwasserausgang angeschlossen sind, ist hingegen ein Betrieb im Eco-Modus nicht möglich, da im Fehlerbetrieb eine wiederholte Überprüfung der Anschlüsse erfolgen soll, was nur möglich ist, wenn der Wärmetauscher in einem Betriebstemperaturbereich betrieben wird. Auch weitere Einstellmöglichkeiten durch einen Benutzer können im Fehlerbetrieb eingeschränkt sein.The controller preferably has a memory in which the following states can be stored:

• 0: check necessary,
• 1: normal operation,
• 2: error operation,

wherein an operation of the water heater takes place in dependence on the stored state. One byte is required for storing the respective state, which has the advantage over storage in a simple bit that it is less error-prone. Before the first initialization or the first startup of the water heater is stored in the memory that a review is necessary. This ensures that a check is made after every new connection, whether the hot water pipe is correctly connected to the hot water outlet and the cold water pipe is correctly connected to the domestic water inlet. If this is affirmative, the water heater is operated in normal operation and this state is stored in the memory. In normal operation, various settings can be made by a user, for example, the water heater can be operated in an Eco mode or a comfort mode. In the Eco mode, a substantial cooling of the heat exchanger is allowed for energy saving, if no liquid is tapped. In fault mode, ie when the hot water pipe at the service water inlet and the cold water pipe are connected to the hot water outlet, however, operation in eco mode is not possible, since in error operation a repeated check of the connections should be made, which is only possible if the heat exchanger in an operating temperature range is operated. Other settings by a user may be limited in error mode.

Preferably, the controller is designed such that when connecting the hot water pipe at the service water inlet warm liquid is available at the service water inlet and optionally displays the fault mode, in particular a temperature of the heat exchanger is increased or kept constant or regulated depending on the temperature at the service water inlet. Thus, a sufficient operation of the water heater is also possible with a permutation of the connections. By providing a corresponding display, an installer can then relatively quickly find out and fix the cause of the error. However, it is not necessary to shut down the water heater until the fault is rectified. Rather, limited but limited operation is possible.

The object is achieved by a method having the features of claim 6.

In this case, a passage direction of the liquid is determined by the heat exchanger, wherein a control of an actual temperature of the liquid to a predetermined desired temperature in dependence on the passage direction. The water heater is so both in a direction of passage from the hot water inlet to the hot water outlet, ie with correct connection of hot water pipe and cold water pipe, as well as in the reverse flow direction from the hot water outlet for domestic water input operable. In this case, depending on the passage direction different.

Control parameters are used. For example, the target temperature in a direction of passage from the hot water output to the service water input can be fixed, while the target temperature at the right direction of passage from the hot water input to hot water output by a user is changeable, for example by selecting the Eco mode.

Advantageously, the passage direction is determined by measuring the temperature at the service water inlet, optionally in conjunction with measuring the temperature at the hot water outlet and / or with a flow sensor at the service water inlet or hot water outlet. An increase in temperature at the service water inlet is a sign that the hot water pipe is connected to the service water inlet, ie the direction of flow from the hot water outlet to the service water inlet leads. However, this fault detection can be made more reliable by the fact that the temperature at the hot water outlet is detected. If the temperature at the service water inlet when dispensing liquid with respect to the temperature rises at the hot water outlet, there is clearly a run from the hot water outlet to the hot water inlet. A directional flow sensor can also be used to determine the flow direction. However, to control the actual temperature of the liquid dispensed then a detection of the temperature at the service water inlet is required.

Preferably, a temperature T1 is measured at the service water inlet and a temperature T2 at the service water outlet, wherein the temperature T2 is regulated to desired temperature when the temperature T2 is greater than the temperature T1, wherein the temperature T1 is controlled to target temperature, if Temperature T1 is greater than the temperature T2. Thus, both the temperature at the service water inlet and at the service water outlet are recorded. The basis for the regulation is always the warmer recorded temperature, which provides reliable information about the direction of flow within the heat exchanger. If the temperature T2 at the hot water outlet is greater than the temperature T1 at the domestic water input, there is a normal operation, while when the temperature T1 at the hot water inlet is higher than the temperature T2 at the hot water outlet, there is an error operation. Depending on whether normal operation or fault operation is present, the control can be operated with different programs or in different modes.

• 0: Überprüfung notwendig,
• 1: Normalbetrieb,
• 2: Fehlerbetrieb,

wobei beim Initialisieren des Durchlauferhitzers und/oder nach längeren Stillstandszeiten der Speicher auf ”0” gesetzt wird, wobei insbesondere im Fehlerbetrieb eine Überprüfung der Durchlaufrichtung wiederholt wird. Im Auslieferungszustand, also vor einer ersten Initialisierung bzw. einem ersten Hochfahrendes Durchlauferhitzers, ist im Speicher hinterlegt, dass eine Überprüfung notwendig ist. Demzufolge erfolgt beim ersten Hochfahren eine Überprüfung, ob die Warmwasserleitung und die Kaltwasserleitung korrekt angeschlossen sind. Dafür wird der Wärmetauscher erwärmt und die Temperatur. am Brauchwassereingang erfasst. Gegebenenfalls wird zusätzlich die Temperatur am Brauchwasserausgang erfasst und mit der Temperatur am Brauchwassereingang verglichen. Es ist auch denkbar, mithilfe eines Durchlaufsensors zu erfassen, ob eine Abgabe an Flüssigkeit erfolgt. Wenn nun die Temperatur am Brauchwassereingang höher wird als am Brauchwasserausgang, wird im Speicher hinterlegt, dass der Durchlauferhitzer im Fehlerbetrieb betrieben wird. Steigt die Temperatur am Brauchwasserausgang jedoch über die Temperatur am Brauchwassereingang an, wird hinterlegt, dass der Durchlauferhitzer im Normalbetrieb betrieben wird. Im Fehlerbetrieb sind dabei Benutzervorgaben nur eingeschränkt zulässig, wobei beispielsweise der Betrieb im Eco-Modus nicht möglich ist, so dass kein übermäßiges Abkühlen des Wärmetauschers erfolgt. Dabei ist im Fehlerbetrieb vorgesehen, dass eine periodische erneute Überprüfung der Durchlaufrichtung erfolgt.It is particularly preferred that one of the following three states is stored in a memory:

• 0: check necessary,
• 1: normal operation,
• 2: error operation,

wherein the memory is set to "0" during initialization of the water heater and / or after longer periods of standstill, wherein in particular a check of the flow direction is repeated in error mode. In the delivery state, ie before a first initialization or a first startup of the instantaneous water heater, it is stored in the memory that a check is necessary. As a result, the first start-up will check whether the hot water pipe and the cold water pipe are correctly connected. For this, the heat exchanger is heated and the temperature. recorded at the service water inlet. If necessary, the temperature at the dhw output is additionally recorded and compared with the temperature at the dhw input. It is also conceivable to detect with the aid of a flow sensor whether a discharge of liquid takes place. If now the temperature at the dhw input is higher than at the dhw output, it is stored in the memory that the flow heater is operated in error mode. However, if the temperature at the service water outlet rises above the temperature at the service water inlet, it is deposited that the water heater is operated in normal operation. In error mode, user defaults are only permitted to a limited extent, for example, operation in the Eco mode is not possible, so that there is no excessive cooling of the heat exchanger. It is provided in error mode that a periodic re-examination of the direction of passage takes place.

Preferably, a temperature of the heat exchanger is maintained between an upper and a lower limit temperature in the error mode. This can be done for example by means of fuzzy control.

Preferably, a higher setpoint is used in error mode than in normal mode. This ensures that even with incorrect connection of the cold water pipe and the hot water pipe sufficiently warm liquid is discharged from the heat exchanger to the hot water pipe. At the same time, the error detection is improved by the increased setpoint, since the increase in the setpoint leads to an increased temperature increase in the dispensed liquid.

The invention will be described below with reference to a preferred embodiment in conjunction with the drawings. Herein show:

1 a flow heater in a schematic view and

2 a possible procedure.

In 1 is schematically a water heater 1 with a heat exchanger 2 shown, wherein the heat exchanger 2 a service water entrance 21 and a service water outlet 22 having. Via a secondary circuit 5 becomes the heat exchanger 2 Heat energy supplied in a heat source 52 is produced. There is a Transfer of heat energy from the heat source 52 to the heat exchanger 2 using a liquid, especially water, through a pump 51 is moved.

For a correct installation is a cold water pipe 31 at the service water entrance 21 and a hot water pipe 32 at the service water outlet 22 arranged. A passage direction through the heat exchanger 2 then takes you from the service water inlet 31 to the hot water outlet 32 , This takes place in the heat exchanger 2 a transfer of heat energy to the liquid, so a heating of the liquid, which heats to the hot water pipe 32 is delivered. In the following it is assumed that water is used as liquid, but also the use of other liquids is conceivable.

The heat exchanger 2 Heat energy transferable to the water is provided by means of a controller 4 regulated. Usually, this is a discharge amount using a flow sensor 8th detected, the controller determines how much heat in the heat exchanger depending on the discharge amount 2 must be transferred. The through the secondary circuit 5 introduced heat energy is then supplied accordingly. Such a control works with correct connection of cold water pipe and hot water pipe, so if the flow direction from the hot water inlet to the hot water outlet is satisfactory. A regulation using a temperature sensor 7 that is at the service water outlet 22 is arranged, allows a regulation of the target temperature.

In the reverse direction of passage, so if incorrectly the cold water pipe 31 at the service water outlet 22 and the hot water pipe 32 at the service water entrance 21 are connected, gives the flow sensor 8th but no more signal and also the temperature sensor 7 at the service water outlet 22 always indicates only a constant temperature, namely that of the supplied cold water. As a result, a controlled release of hot water is not possible.

According to the invention is now provided at the service water inlet 21 a temperature sensor 6 to arrange. Such a temperature sensor 6 has a correct connection, so a flow direction of the hot water inlet 21 to the hot water outlet 22 , another monitoring function, namely the detection of preheated water at the service water inlet 21 , For example, to determine solar water heating. Once the water temperature at the service water entrance 21 then over at the service water outlet 22 is, the water heater 1 or its heat source 52 not activated. Furthermore, the temperature sensor 6 used to adjust the water temperature at the service water outlet 22 with a predictive control, namely taking into account the water inlet temperature to optimize. However, it allows a reliable determination of the direction of flow and a regulation of the target temperature of the liquid dispensed even if the hot water pipe at the service water inlet 21 connected, the water heater 1 so it's going the wrong way around.

With correct connections, ie with a connection of the cold water line 31 at the service water entrance 21 and the hot water pipe 32 at the service water outlet 22 , is a normal operation. An error operation occurs when the heat exchanger 2 operated in the opposite direction, so the cold water pipe 31 at the service water outlet 22 and the hot water pipe 32 at the service water entrance 21 connected. Whether an error operation is present, can in a display 9 be displayed so that, for example, immediately recognizable by an installer, whether the hot water pipe 32 and the cold water pipe 31 correct on the heat exchanger 2 are connected.

In 2 schematically a possible sequence of the method according to the invention is shown. After a first installation, ie at a first startup of the water heater 1 or after a prolonged interruption of operation, the heat exchanger 2 initially heated. When a hot water delivery then the temperature at the service water inlet 21 detected. If necessary, the heat source can now 52 provide more heat, in which case the temperature at the service water inlet 21 is recorded continuously. A temperature at the service water entrance 21 before starting the heat source 52 is compared with a later recorded temperature. If a temperature increase has occurred, the direction of flow is from the hot water outlet 22 to the service water entrance 21 , so there is an error operation. Accordingly, at the service water entrance 21 Hot water discharged and there is a control of the actual temperature at the service water inlet 21 , When the temperature at the service water entrance 21 decreases, although the heat source 52 Heat energy to the heat exchanger 2 supplies are the cold water pipe 31 and the hot water pipe 32 correctly connected and there is a normal operation, in the hot water at the hot water outlet 22 is discharged, so that the temperature at the hot water outlet 22 is regulated to the target temperature.

Heating the water heater 1 at the first start-up takes place regardless of which mode of the water heater 1 is set, so if, for example, an Eco mode was selected, in which a heating of the heat exchanger 2 only as needed.

If now in addition to the temperature detection at the service water inlet 21 also a temperature detection at the hot water outlet 22 takes place, by a comparison of these two temperatures relatively easy to determine the direction of passage. If, during the delivery of liquid, the temperature at the tap water outlet 22 about the temperature at the service water entrance 21 rises, the water heater is in normal operation. When the temperature at the service water entrance 21 in contrast to the temperature at the hot water outlet 22 rises, is the water heater 1 in error mode. The error detection can be additionally improved by the provision of a flow sensor.

An error operation can also be assumed if no cooling at the service water inlet during the delivery of liquid 21 , so no temperature decrease takes place.

The method according to the invention can easily be additionally implemented and also retrofitted into existing instantaneous water heaters. This procedure only comes into effect when the cold water pipe 31 and the hot water pipe 32 not connected correctly. This makes it possible to issue even reliably heated liquid, if no correct connections were made, the water heater 1 So it is operated in error mode. At the same time detection of the error is very easy, so that rework can be done very quickly and thus cause few costs.

Checking the flow direction by warming up the water heater 1 takes place regardless of a set mode, that is, for example, regardless of whether the water heater 1 is operated in an Eco mode or a comfort mode. In fault mode, a temperature of the heat exchanger 2 held between a lower and an upper limit temperature, the heat exchanger 2 So always kept at an elevated temperature. In normal operation, it is possible, for example in the setting Eco mode, a substantial cooling of the heat exchanger 2 to allow to save energy.

While conventionally those of the heat exchanger 2 Controlled on the liquid to be dispensed heat energy in dependence on the discharge amount is provided according to the invention, a temperature at the service water inlet 21 to capture, so that a regulation of the temperature of the liquid output is possible even if the cold water pipe 31 and hot water pipe 32 are reversed connected.

Claims (10)

Instantaneous water heater ( 1 ) with a heat exchanger ( 2 ) for heating a continuous liquid which has a service water inlet ( 21 ) for connecting a cold water line ( 31 ) and a hot water outlet ( 22 ) for connecting a hot water pipe ( 32 ), wherein a controller ( 4 ) is provided for controlling or regulating a temperature of the liquid, characterized in that a temperature sensor ( 6 ) at the service water entrance ( 21 ) is arranged. Instantaneous water heater according to claim 1, characterized in that a flow sensor ( 8th ) at the service water entrance ( 21 ) and / or at the hot water outlet ( 22 ) is arranged. Instantaneous water heater according to one of claims 1 or 2, characterized in that the heat exchanger ( 2 ) is connected to a secondary circuit having a pump and a heat source which is controlled by the controller ( 4 ) are controllable. Flow heater according to one of claims 1 to 3, characterized in that the controller ( 4 ) has a memory in which the following states can be stored: 0: check necessary, 1: normal operation, 2: error operation, with an operation depending on the stored state. Flow heater according to one of claims 1 to 4, characterized in that the controller ( 4 ) is designed such that when connecting the hot water pipe ( 32 ) at the service water entrance ( 21 ) warm liquid at the service water entrance ( 21 ) and optionally an advertisement ( 9 ) indicates the error operation, wherein in particular a temperature of the heat exchanger ( 2 ) or kept constant or depending on the temperature in the domestic water inlet ( 21 ) is regulated. Method for operating a continuous flow heater, in particular according to one of claims 1 to 5 with a heat exchanger for heating a continuous liquid, characterized in that a passage direction of the liquid is determined by the heat exchanger, wherein a control of an actual temperature of the liquid to a predetermined desired -Temperature as a function of the direction of passage takes place. A method according to claim 6, characterized in that a passage direction is determined by measuring the temperature at the service water inlet, optionally in conjunction with measuring the temperature at the hot water outlet and / or with a flow sensor at the service water inlet or at the hot water outlet. Method according to one of Claims 6 or 7, characterized in that a temperature (T1) is measured at the service water inlet and a temperature (T2) at the service water outlet, the temperature (T2) being regulated to the setpoint temperature when the temperature (T2) is higher than the temperature (T1) while the temperature (T1) is controlled to the target temperature when the temperature (T1) is higher than the temperature (T2). Method according to one of claims 6 to 8, characterized in that, in particular during fault operation, a temperature of the heat exchanger is maintained between a lower and an upper limit temperature. Method according to one of claims 6 to 9, characterized in that in error operation, a higher target value is used than in normal operation.

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