DE102009004294B4 - Hot water tank and method for its charging - Google Patents

Abstract

A method for charging a storage container of a hot water tank with warm water, comprising a standby area and a preheating area, the standby area usually being heated to a higher temperature by a first heat generator, and the preheating area being generally tempered lower by a second heat generator with fluctuating heat supply that • the hot water tank switches into a comfort operating mode in times when there is no or insufficient supply of heat to the hot water tank from the second heat generator, in which the storage tank is charged completely or almost completely at a higher temperature across both areas, and that • the hot water tank switches to a normal operating mode in good time before the second heat generator provides sufficient heat to be fed into the hot water tank switches so that the preheating area is discharged again when there is a supply of heat on the part of the second heat generator due to hot water extraction or cooling and / or is again ready for the low-temperature heat supply on the part of the second ...

Description

The invention relates to a method for charging a hot water tank according to the preamble of claim 1 and a hot water tank according to the preamble of claim. 9

Generic hot water tanks are well known in the art. They are used for heat storage with the applications DHW heating and storage or heating heat buffering. Storage medium is water that is heated by one or more heat generators.

From the DE 101 38 388 A1 For example, a method is known for charging a storage tank of a hot water storage tank comprising warm water with a standby area and a preheating area, the standby area generally being heated to a higher temperature by a first heat generator, and the preheating area generally being tempered by a second heat generator with fluctuating heat supply is at least two sensors for detecting the heat content and the temperature übereinader arranged in the upper Nachheizbereich of the hot water tank, wherein the lowest sensor is selected so that it detects the maximum Nachheizvolumen that the other sensors are assigned intermediate values of Nachheizvolumens and that the hot water -Ladepumpe either water from the upper or lower storage area can be fed, so that the energy consumption for reheating can be reduced to a minimum.

From the DE 10 2007 019 351 B3 a method for charging a storage container is known, wherein a heat source as a priority heat source and the other heat sources are determined as subordinate heat sources, and a rule set for determining a ranking, the rule set depends on the temperature of the hot water tank and the energy flows of all heat sources in the hot water tank.

Solar assisted domestic hot water storage tanks comprise a storage tank having an overhead standby area and a preheat area disposed thereunder. The stored in the ready area drinking water volume is usually heated by a fossil-fired, first heat source and heated to domestic hot water target temperature. The stored in the preheating potable water volume is usually preheated by a solar-powered, second heat source to lower temperatures. In a hot water tap water is withdrawn from the standby area and replaced by usually lower tempered water from the preheating, the latter in turn undergoes a replenishment by fresh, flowing into the preheating cold water. The preheat water rising into the ready area is heated to the set temperature before it is tapped and used in the standby area.

A temperature sensor in the standby area is provided for monitoring the temperature of the domestic hot water temperature. If the actual temperature falls below a predefinable limit value due to tapping or cooling, a charging process is started and the first heat generator recharges the ready area to the setpoint temperature. Thus, this readiness volume for the domestic hot water supply and the comfort requirements of the user is available.

Changing weather conditions as well as the effects of the sun's position resulting from the daytime and seasonal changes cause the solar radiation supply to fluctuate. With sufficient supply of solar energy, the second heat generator, such as a solar thermal tube or flat collector, at least take over a large part of the drinking water heating and also heat the standby area up to target temperature. In addition, there are times when the solar collector generates little or no heat due to lack of solar radiation. In addition to the supply of solar generated heat in the hot water tank, of course, other renewable energy can be used.

To control the feeding of the heat of the second heat generator into the storage tank, both the second heat generator and the preheating area of the storage tank have a temperature sensor. A heat transfer fluid that can circulate between the second heat generator and the preheating area, serves for the heat transfer from the second heat generator to the hot water tank. For heat transfer from the heat transfer fluid to the water in the storage tank is usually arranged in the preheating area, through which flows through the heat transfer fluid heat exchanger coil. If the fluid temperature measured in the second heat generator is higher than the water temperature in the preheating area, then the heat transfer fluid is usually pumped by a pump and the heat is fed into the storage tank. If the water temperature in the preheating area is greater than or equal to the fluid temperature in the solar collector, the fluid circulation and thus the heat input and the use of solar-generated heat is stopped. The larger the water volume in the preheating area, the slower its temperature rises during the heat supply and the longer and more heat can absorb it. However, the volume of water in the preheating area is also heated by heat conduction from the water in the standby area.

In order to increase the proportion of heat generated in the second heat generator to the total heat, the first heat generator may therefore only heat as little water as possible. On the other hand, as a rule, only the volume of water heated by the first heat generator in the standby area of the hot water supply and satisfying the comfort requirements of the user and must be sufficiently large dimensions for this reason. For space and cost reasons, in turn, a rather small storage tank volume is sought.

The invention has for its object to provide a method for charging a hot water tank, which overcomes the disadvantages of the prior art and in particular provides an improved domestic hot water supply for higher comfort demands and yet grants a high solar usage share with limited storage tank volume.

Furthermore, the invention has the object to provide a hot water tank for performing a method for improved domestic hot water supply for higher comfort requirements, which grants a high solar usage share with limited storage tank volume.

This is achieved by the objects with the features of claim 1 and 9 according to the invention. Advantageous developments can be found in the dependent claims.

The method according to the invention for charging a storage tank of a hot water storage tank comprising warm water with a standby area and a preheating area, wherein the standby area is usually heated to a higher temperature by a first heat generator, and the preheating area is usually tempered lower by a second heat source with fluctuating heat supply, is characterized in that the hot water tank in times of a lack or for supply to the hot water tank too low heat supply by the second heat generator switches to a comfort mode of operation, in which the storage tank is charged by the first heat generator completely or almost completely higher temperature over both areas (convenience charge is in progress). If the second heat generator is, for example, a solar system with solar collectors, and solar radiation is no longer to be expected because of the weather or because of the daily position of the sun, a control associated with the hot water storage can switch to a comfort operating mode in which the user a larger volume of hot water is provided. This is done without a possible solar yield is reduced, provided that the hot water tank switches back to a normal operating mode in time before resuming a sufficient supply of heat in the hot water tank heat supply from the second heat source. This is because the preheating area is again discharged when the supply of heat by the second heat generator resumes due to hot water extraction or cooling, or is again ready for reception for the low-temperature heat supply on the part of the second heat generator.

In an advantageous embodiment, a comfort charging process begins at a predefinable time Z. The hot water tank is completely or almost completely charged over both areas, ie on the standby and preheating, from the first heat generator, if at the time Z one at a predetermined location S measured in the preheating water temperature T falls below a first predetermined temperature limit T1. This may be a value which is less than a setpoint temperature by the difference of a switch-on hysteresis. The comfort charging process is terminated, for example, after a predefinable charging period D and / or the hot water tank is switched back to a normal operating mode. Or if the measured at the predetermined point S in the preheating water temperature T exceeds a second predetermined temperature limit T2, wherein T2 is greater than or equal to T1. T2 can be, for example, the domestic hot water temperature, which also represents the switch-off criterion for the charging of the ready area. Upon completion of the comfort charging process, the domestic hot water storage tank provides a significantly larger domestic hot water volume for the user, resulting in unequaled domestic hot water comfort. However, the heat output of the second heat generator is not diminished. Within the duration of a comfort mode of operation, the number of comfort charging operations may be limited to one or more comfort charging operations may be performed depending on the hot water withdrawal and the cooling down behavior.

In the normal operating mode, the temperature sensor arranged at a predefinable point S in the preheating region of the hot water storage tank serves to monitor an injection of the low-temperature heat provided by the second heat generator into the hot water storage tank. If a specifiable switch-on criterion is met, the heat supply starts, if a predefinable switch-off criterion, the feed is terminated. In the case of solar heat generation, the temperature sensor is the solar reference temperature sensor in the preheating area of the storage tank. The switch-on criterion is usually given when the temperature of the solar fluid in the solar collector above the corresponding reference water temperature in the preheating of the storage tank, and at a point S, which is important for the transfer of heat from the solar fluid to the storage water, as they are for the Heat transfer required temperature gradient compared to the solar fluid temperature describes. The heat input into the hot water tank is started by circulating the solar fluid. The switch-off criterion is given accordingly if the temperature in the solar collector is equal to or less than the reference temperature in the preheating area. The heat supply is stopped by stopping the circulation of the solar fluid.

In the comfort mode of operation, the same temperature sensor serves to monitor an injection of the high-temperature heat provided by the first heat generator into the hot water storage tank. When a predefinable switch-on criterion of the comfort charging process is started, it is terminated when a predefinable switch-off criterion. The switch-on criterion may be, for example, the undershooting of a minimum temperature value T1 at the point S, switch-off criterion may be the achievement of a setpoint temperature T2.

In a suitable design, the comfort charging process is activated only once a day. Favorable times Z for a comfort charging process are for the example of the supply of solar heat in the later afternoon, evening and / or night hours. They can be given by fixed, specifiable times. In another embodiment, possible times Z can be calculated by a control device associated with the hot water storage on the basis of stored operating data from the past. By selecting a time Z according to one of the aforementioned manners, it is ensured that the second heat generator provides no or almost no heat that can be stored for a sufficiently long duration after the comfort charging process, for example from the evening until the next morning. In this sufficiently long duration, the user taps as much warm water, and enjoys in this way the increased hot water comfort, until the preheating area is finally cool (discharged) and is ready, for example, for a new, effective solar use. By timely switching back from the comfort mode to the normal operating mode, the preheating area is already discharged again (for example, due to hot water extraction or cooling) when a heat supply by the second heat generator (example: re-entering solar radiation the following morning) and stands for renewed feed of, for example, solar heat available again. This ensures that there is no reduction of possible solar yield. Timely switching back, for example, after a single charge the hot water tank on its standby and preheating area.

A controller associated with the hot water storage device can store selected operating data. From these "empirical values", the control can derive suitable times Z for a comfort charging process. Thus, a result of the derivative may be that the collector temperature in a current, just past period on average, for example, 18 clock has not enough for a heat supply to the memory. On the basis of this "experience", the regulation will then switch to the comfort mode of operation at 6 pm on the current evening in the "assumption" that no usable heat will be generated at 6 pm on the current evening either. The stored operating data from the past used for this "learning process" of the hot water tank control usually relate to the time course of a parameter and can be: hot water consumption, heat consumption, heat supply of the second heat generator, solar collector temperature, solar pump running time, water temperature in the ready area and in the preheating area and so on. Such a learning process can additionally be based on year-round data, for example on the position of the sun. Thus, a safe switch over to the comfort operating mode with high domestic hot water comfort takes place all year round, without the yield of the second heat generator, for example the solar yield, being reduced.

If, due to the expiration of a charging period D, the comfort charging process is ended and / or the hot water storage is switched back into a normal operating mode, explicit measurements, such as temperature measured values, may be dispensed with. This makes monitoring much easier. Thus, the loading period D can be determined on the basis of a number of predetermined and / or assumed values selected from the group consisting of domestic hot water target temperatures, assumed hot water actual temperatures and the storage volume, respectively in the standby area and in the preheating area, and a heat output of the first heat generator. However, it is also possible to use explicit measured values, such as the actual hot water temperatures in the standby area and in the preheating area, to determine the charging duration.

The hot water storage tank according to the invention comprises a standby area, which is generally heated to a higher temperature by a first heat generator, and a preheating area, which is generally tempered by a second heat generator, and is designed to carry out a method according to one of claims 1 to 8. At a predefinable point S in the preheating region, the hot water tank has a temperature sensor, which is assigned during a normal operating mode of a monitoring device for feeding the provided by the second heat generator low-temperature heat in the hot water tank. During a comfort mode of operation, the temperature sensor is associated with a monitoring device for feeding the high temperature heat provided by the first heat generator into the hot water tank. This allows different functions to be performed with a temperature sensor in different operating modes.

With the invention, there is a hot water tank and a method for improved domestic hot water supply for higher comfort demands that grant despite high storage tank volume a high proportion of solar usage.

Reference to the drawing, an embodiment of the invention will be explained. The drawing shows in the single figure:

Figure hot water tank

The figure shows a hot water tank 1 with enveloping insulation (hatched), a storage tank 2 with overhead standby area 3 and bottom preheating area 4 includes. A dashed line indicates approximately the limit of the two areas.

In a normal operating mode, the standby area becomes 3 charged by a first heat generator, not shown, ie in the standby area 3 present drinking water volume is heated by cooling or cold drinking water from the lower area of the storage tank via a cold water extraction line 5 taken outside the hot water tank heated to domestic hot water temperature and via a hot water supply 6 is fed back into the upper area of the storage tank. The circulation takes place by means of a circulating pump, not shown. The normal charging process is performed by a temperature sensor defining the extent of the standby area downwards 7 monitored, falls below a temperature limit, the charging process triggers, on reaching a further temperature limit, the charging process is terminated. The heated drinking water can via the hot water extraction line 8th taken and supplied to the consumption by a user. The amount of hot water removed from the storage tank is replaced by cold water via the cold water supply pipe 9 is supplied to the memory.

A second heat generator (not shown) also provides heat at a generally lower temperature level. A heat transfer medium can via supply and return lines between the second heat source and heat exchanger 10 circulate. Is the fluid temperature in the second heat generator (eg solar collector) higher than that of the temperature sensor? 11 (eg solar reference temperature sensor) measured water temperature at the point S in the preheating area 4 , so usually the heat in the hot water tank 1 be fed.

In a comfort operating mode, the temperature sensor receives 11 in the preheating area 4 another function, ie its measured values T are assigned and evaluated differently in a control device, not shown. Then the temperature sensor serves 11 monitoring a comfort charging process. This is the hot water tank 1 completely or almost completely charged over both storage areas by the first heat generator, so that then there is a much larger volume of water at a higher temperature. The comfort charging process is started when on the temperature sensor 11 a first temperature limit T1 is exceeded. It is terminated after the expiry of a predefinable charging period D, or if at the temperature sensor 11 a second temperature limit T2 is exceeded.

Claims (9)

A method for charging a storage tank of a hot water tank with warm water comprising a standby area and a preheating area, the standby area usually being heated to a higher temperature by a first heat generator, and the preheating area generally being tempered by a second heat source with fluctuating heat supply, characterized in that the hot water storage tank switches over in times of a lack of supply or for an injection into the hot water storage by the second heat generator in a comfort mode of operation, in which the storage tank from the first heat generator is fully or almost completely charged over both areas higher tempered, and that • the hot water storage in good time before resubmission of sufficient for an injection into the hot water tank heat supply from the second heat generator switches to a normal operating mode, so that the preheating is discharged when a supply of heat from the second heat generator due to hot water withdrawal or cooling again and / or again is receptive to the low-temperature heat supply from the second heat generator. Method according to claim 1, characterized in that • starting at predeterminable times Z a comfort charging process is started, in which the hot water tank is completely or almost completely charged via both storage areas of the first heat generator, if at the time Z a measured at a predetermined point S in preheating water temperature T a first predetermined temperature Threshold T1 falls below, and that • the comfort charging process is ended and / or the DHW cylinder returns to a normal operating mode - After expiry of a predefinable charging duration D, or - When the water temperature T measured at the predeterminable point S in the preheating region exceeds a second predeterminable temperature limit value T2 ≥ T1. Method according to Claim 1 or 2, with a temperature sensor arranged at a predefinable point S in the preheating area of the hot water storage tank, which in a normal operating mode serves to monitor an injection of the low-temperature heat provided by the second heat generator into the hot water storage tank, in particular if a predefinable switch-on criterion is met the supply starts and ends when a predefinable switch-off criterion the supply, characterized in that the temperature sensor in a comfort mode of operation monitoring the supply of the provided by the first heat generator high-temperature heat in the hot water tank, especially when a predetermined switch-on criterion the comfort Charging process starts and ends the comfort charging process when a predefinable switch-off criterion. Method according to one of claims 1 to 3, characterized in that the comfort charging process is activated only once a day. Method according to one of claims 1 to 4, characterized in that possible times Z for a comfort charging process in the afternoon, evening and / or night hours are. Method according to one of claims 1 to 5, characterized in that possible times Z are given for a comfort charging process by fixed, predefinable times. Method according to one of claims 1 to 6, characterized in that possible times Z for a comfort charging process are calculated by a controller associated with the hot water storage on the basis of stored operating data from the past, it being ensured by taking into account these operating data that The second heat generator no longer provides any or almost no heat which can be stored starting from time Z for a sufficiently long duration, and / or • the preheating area is discharged when a heat supply is resumed by the second heat generator due to hot water extraction or cooling. Method according to one of claims 1 to 7, characterized in that the loading period D on the basis of a number of predetermined and / or assumed and / or measured values selected from the group comprising hot water target temperatures, actual hot water temperatures and storage volumes - each in the standby area and in preheating - and heat output of the first heat generator is set. Hot water tank with a usually higher tempered by a first heat generator standby area and a generally lower by a second heat source preheating for performing a method according to one of claims 1 to 8, wherein arranged at a predetermined location S in the preheating of the hot water tank, a temperature sensor is, during a normal operating mode 'assigned to a monitoring device for feeding the provided by the second heat generator low-temperature heat in the hot water tank, characterized in that the temperature sensor during a comfort mode of operation of a monitoring device for feeding the provided by the first heat generator highly tempered heat is assigned to the hot water tank.

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