Water system with a continuous flow heater and a flushing station

Abstract

The present invention relates to a water system with a warm water line (3) for supplying at least one first consumer (4, 4a, 4b) connected thereto with warm water and a continuous flow heater (1), in which cold water introduced into the latter is heatable, connected to said warm water line (3). In case warm water remains in the continuous flow heater, because it is only partially consumed, limescale deposit can reduce the performance and the service life of the continuous flow heater. Limescale deposit is particularly likely to happen in stagnant warm water. The present invention aims to solve aforesaid problem in that a flushing station (2) connected to said warm water line (3) is provided, by way of which stagnant water in said warm water line can be drained in a chronological sequence until the water contained in said continuous flow heater (1) is below a predetermined setpoint temperature.

Claims

1. A water system with: a warm water line supplying at least one first consumer connected thereto with warm water; a continuous flow heater connected to the warm water line, wherein cold water introduced into the continuous flow heater is heated; a flushing station connected to the warm water line for flushing the warm water line; wherein the flushing station comprises a waste port and a flushing valve for discharging water in the warm water line (3) into the waste port (26); a control device for opening or closing the flushing valve of the flushing station; and a temperature sensor associated with the continuous flow heater for measuring the temperature of water contained in the continuous flow heater; wherein the control device is configured to open the flushing valve of the flushing station as soon as a heating operation of the continuous flow heater has been switched off; and wherein the control device is configured to close the flushing valve of the flushing station once the temperature measured by the temperature sensor drops below a predetermined setpoint temperature.

2. The water system according to claim 1, wherein the control device also switches on or off the heating operation of the continuous flow heater.

3. The water system according to claim 1, wherein the flushing station is configured such that water in the warm water line is drained until the water contained in the continuous flow heater is below a temperature of 40 C.

4. The water system according to claim 1, wherein the flushing station is configured such that water of the warm water line is always drained when the at least one first consumer has not tapped water from the warm water line over a predetermined period of time.

5. The water system according to claim 2, wherein a flow meter is further provided, by way of which the control device decides whether the warm water line is being flushed.

6. The water system according to claim 1, wherein a cold water line is provided in the water system for supplying at least one second consumer connected thereto with cold water, and in that the flushing station is connected to the cold water line.

7. The water system according to claim 1, wherein the continuous flow heater is formed by a plate heat exchanger with a primary circuit and a secondary circuit and a heat exchanger plate provided between the primary circuit and the secondary circuit, where the fluid flowing through the primary circuit heats the water flowing though the secondary circuit before the water is supplied to the warm water line.

8. The water system according to claim 7, wherein the primary circuit is connected to a heating unit for heating a building, and the secondary circuit is part of a potable or tap water line of a building.

9. The water system according to claim 7, wherein the plate heat exchanger is arranged such that the heat exchanger plate is disposed inclined relative to the direction of gravity.

10. The water system according to claim 6, wherein a water supply line for supplying cold water to the continuous flow heater is provided at the inlet side of the latter, and the cold water line branches off from the water supply line.

11. The water system according to claim 7, wherein the plate heat exchanger is provided in a housing module, with ports provided thereon for a heating feed line and a heating return line, for connecting the primary circuit of the plate heat exchanger to the heating unit, a port for the water supply line, a port for the warm water line, and a port for the cold water line.

12. A water system with: a warm water line supplying at least one first consumer connected thereto with warm water a continuous flow heater connected to the warm water line, wherein water introduced into the continuous flow heater is heated; a water supply line for supplying cold water to the continuous flow heater; a flushing station connected to the warm water line, the flushing station comprising a waste water port and a flushing valve for discharging water in the warm water line into the waste water port; and a control device for switching on or off a heating operation of the continuous flow heater and for opening or closing the flushing valve of the flushing station; wherein the control device is configured to open the flushing valve of the flushing station as soon as the heating operation of the continuous flow heater has been switched off; wherein a temperature sensor associated with the continuous flow heater is provided for measuring the temperature of water contained in the continuous flow heater; and wherein the control device is configured to close the flushing valve of the flushing station once the temperature measured by the temperature sensor drops below a predetermined setpoint temperature.

13. The water system according to claim 12, wherein the flushing station is configured such that the warm water line is always drained when the at least one first consumer has not tapped water from the warm water line over a predetermined period of time.

14. The water system according to claim 12, wherein a cold water line is provided in the water system for supplying at least one second consumer connected thereto with cold water, and wherein the flushing station is connected to the cold water line.

15. The water system according to claim 14, wherein the water supply line is provided at the inlet side of the continuous flow heater, and that the cold water line branches off from the water supply line.

16. A water system with: a warm water line supplying at least one consumer connected thereto with warm water; a continuous flow heater connected to the warm water line, wherein cold water introduced into the continuous flow heater is heated; a water supply line connected to the continuous flow heater for supplying the cold water to the continuous flow heater; a flushing station connected to the warm water line for flushing the warm water line, the flushing station comprising a waste water port and a flushing valve for discharging water in the warm water line into the waste water port; and a control device for opening or closing the flushing valve of the flushing station; wherein a temperature sensor is provided at an outlet of the continuous flow heater for measuring the temperature of water contained in the continuous flow heater; wherein a flow sensor is provided at an inlet of the continuous flow heater for determining whether tapping of warm water from the warm water line via the consumer has terminated; and wherein the flushing station is provided downstream of the at least one consumer; wherein the control device is configured to open the flushing valve of the flushing station as soon as a heating operation of the continuous flow heater has been switched off; and wherein the control device is configured to close the flushing valve of the flushing station once the temperature measured by the temperature sensor drops below a predetermined setpoint temperature.

17. The water system according to claim 16, wherein the continuous flow heater is a plate heat exchanger arranged in a heat exchanger housing module, the heat exchanger housing module having a connection port for each of a heating feed line, a heating return line, the warm water line and the water supply line, wherein the heating feed line and the heating return line are connected to a 5 primary circuit of the plate heat exchanger and the warm water line and the water supply line are connected to a secondary circuit of the plate heat exchanger, the primary circuit and the secondary circuit being separated by at least one heat exchanger plate.

Description

(1) Further details and advantages of the present invention shall become apparent from the following description of embodiments in combination with the drawing, in which:

(2) FIG. 1 shows a first embodiment of a water system according to the invention;

(3) FIG. 2 shows an example of a continuous flow heater designed as a plate heat exchanger which is useful for understanding the present invention;

(4) FIG. 3 shows a second embodiment of a water system of the present invention; and

(5) FIG. 4 shows an example of a flushing valve, which is contained in a flushing station, by way of which a plurality of floor lines and riser lines are flushed.

(6) FIG. 1 shows an example of a water system according to the invention. It comprises a continuous flow heater 1, a flushing station 2 and a warm water line 3, which connects the continuous flow heater 1 to the flushing station 2. Connected as a consumer 4 to the warm water line 3 are a wash basin tap 4a and a shower tap 4b.

(7) Any number of consumers 4, or even just one consumer 4, can be connected to the warm water line 3 between the continuous flow heater 1 and the flushing station 2. In the present case, the warm water line 3 is a floor line of an apartment. The warm water line 3 can be any warm water line, for example, a line or a line section in a water system of single-family houses or large buildings such as, for example, hospitals. The warm water line 3 can be a floor line and/or a riser line.

(8) The warm water line 3 is connected to a warm water outlet 5 of the continuous flow heater 1. Cooling water flows through a water supply line 6, which is connected to a water supply inlet 7 of the continuous flow heater 1, into the continuous flow heater 1, is heated in the latter and flows as warm water through the warm water outlet 5 into the warm water line 3. The warm water outlet 5 as well as the water supply inlet 7 can be provided as a pipe section or connection port.

(9) In the embodiment according to FIG. 1, the respective connection ports for the warm water outlet 5 and the water supply inlet 7 are arranged in parallel next to one another in order to establish a simple connection to the pipes.

(10) In this case, the continuous flow heater is a so-called plate heat exchanger 1. In a plate heat exchanger 1, heat is transferred via a heat exchanger plate 8, which is shown as a line in the figures, from a fluid flowing in a primary circuit to a fluid flowing in a secondary circuit. In the present case, the fluid flowing in the so-called secondary circuit is the water to be heated by the plate heat exchanger. In the present example, the fluid flowing in the primary circuit is warm water flowing through a heating circuit of a heating system. This heating water flowing in the primary circuit is therefore not consumed and is constantly re-circulated and heated by a heating system (not shown). The water flowing in the secondary circuit is consumed. The term circuit is therefore chosen for purely formal reasons in this respect, because it is not a circuit in the narrow sense, since the water is consumed.

(11) Such a plate heat exchanger is known, for example, from DE 20 2008 003 349 U1, DE 10 2010 018 086 A1 as well as the European patent application with the registration number 16 170 441.6 and the German utility model with the registration reference number 20 2015 003 756. The plate heat exchangers described in these documents are incorporated by this reference into the present disclosure.

(12) The plate heat exchanger is operated following the countercurrent principle, meaning, the cold water to be heated flows via the water supply line 6 into the right upper side of the plate heat exchanger shown in FIG. 1, and is heated therein as it again exits substantially in an inclined manner, flowing downwardly to the left and out from warm water outlet 5.

(13) The heated water arriving from the heating device (not shown in FIG. 1) flows via a heating feed line inlet 9 described in FIG. 1 into the continuous flow heater 1 (see lower left side of the continuous flow heater 1 in FIG. 1), flows along the heat exchanger plate 8 in countercurrent through the continuous flow heater 1, and is returned to the heating in the upper right region of the continuous flow heater 1 through the heating return line outlet 10 of the heat exchanger 1.

(14) The heating feed line inlet 9 and the heating return line outlet 10, as well as the warm water outlet 5 or the water supply inlet 7, respectively, can be provided as pipe segments or connection ports, all of which are arranged in parallel alignment to each another, at least next to each other in the heat exchanger housing module 11 shown schematically in FIG. 1. It is not necessary that the primary circuit actually be connected to a heating unit in a building, it can also be connected to a district heating system or any other possible source of warm fluid.

(15) The heat exchanger housing module 11, like in a second exemplary embodiment illustrated in FIG. 3 and described later, can be designed as a type of in-wall installation box which is installed, for example, at a (water) supply inlet of an apartment and/or a building This embodiment provides a simple connection option. As can be seen in FIG. 3, the heat exchanger housing module 11 can be configured as a kind of sheet-metal box in which also a control device 12 for controlling the continuous flow heater 1 is provided in addition to the continuous flow heater and the individual connection ports.

(16) In addition to the control device 12, a temperature sensor 13 is provided in the embodiment according to FIG. 1 in the heat exchanger housing module 11 on the outlet side at the continuous flow heater 1, specifically at the warm water outlet 5. In addition, a continuous flow sensor 14 is provided on the inlet side at the water supply inlet 7. Both sensors 13, 14 are connected to the control device 12. It is determined in the control device 12 by way of the continuous flow sensor 14 whether the continuous flow heater 1 is in operation, i.e. whether water flows through it and is heated, or whether the water stagnates therein because no warm water is tapped via the consumer 4.

(17) Such a continuous flow sensor 14 can also be used in the primary circuit, e.g. can be provided at the heating feed line inlet 9. The heat transfer is controlled, in particular, by the flow rate in the primary circuit, as is described, in particular, in German utility model application DE 20 2015 103 940.9, the disclosure content of which is incorporated by reference into the present application. The flow rate through the primary circuit is controlled by way of the control unit 12 via the valve 15, which in the present case is provided at the heating return line outlet 10. When it is completely closed, no water flows through the primary circuit and further heating of water in the secondary circuit also does not occur. Such a control of the heat exchanger is also described in German utility model application DE 20 2015 103 940.9, the disclosure content of which is incorporated by reference into the present application.

(18) In the present embodiment, the control device 12 of the continuous flow heater is connected to a further control device 16 in the flushing station 2 by way of a line indicated as a dotted line. The control device 12 of the continuous flow heater 1 provided in the heat exchanger housing module 11, together with the further control device 16 provided in the flushing housing module 17 of the flushing station 2, forms the control device of the combined system shown in FIG. 1.

(19) The essential functions of the inventive controlling of the flushing station 2 described below in dependence of a state of the continuous flow heater 1 are stored, for example, in the control device 12 of the continuous flow heater 1, and the control device 16 of the flushing station 2 is controlled by it in a slave mode.

(20) An example of a flushing station 2 is described, for example, in European patent application EP 1 845 207 A1, the disclosure content of which regarding the flushing station is incorporated by this reference into the present application. The flushing station 2 comprises a flushing valve 25 and, in the simplest case, can be formed by a controlled flushing valve. The flushing valve 25 is controlled by the control device 16 of the flushing station 2 via the line indicated as a dotted line in FIG. 1. In the open state, the flushing valve 25 is closed between the warm water line 3 and a waste water port 17, so that no water can be discharged therethrough. When the control device 16 of the flushing station 2 opens the flushing valve 25, a flow causing a so-called flush flow is created in the warm water line 3 and the water of the warm water line 3 is introduced e.g. via a waste water port 26 into the public sewage supply network. The waste water port 26 can have any configuration.

(21) Flushing via the flushing station is performed, for example, in the system known from European patent application EP 1 845 207 A1 in order to reduce the risk of germs forming, since the water in the line stagnates when water is not tapped by the consumer. By flushing, i.e. actuating the flushing valve 25 in dependence of the use by the consumers, the risk of such germs forming is reduced. For this purpose, a predefined flushing plan can be stored in the control device 16 of the flushing station 2. The functions stored in the control device of the flushing station 2 can in the present example alternatively also be stored in the control device 12 of the continuous flow heater 1 because these two elements communicate with one another and together form a control device.

(22) Advantageously, the new functions of the continuous flow heater 1 provided by the present invention as well as other functions of the continuous flow heater 1 are stored as program codes in the control device 12 of the continuous flow heater 1. The control parameters of the flushing station 2 are advantageously stored, e.g. in the control device 16 of the flushing station 2

(23) The control device 12 of the continuous flow heater 1 can instruct the control device 16 of the flushing station 2 to open the flushing valve 25 once a condition is fulfilled or it is detected in the continuous flow heater that flushing is required to reduce the risk of calcification.

(24) Similarly to the continuous flow heater 1 which can be provided in a heat exchanger housing module 11, the flushing station 2 is provided in a flushing station housing module 17 which can be configured as an in-wall installation box, as described above for the heat exchanger housing module 11. This flushing station housing module 17 can be provided as a separate element in the building. However, it is also possible to combine the heat exchanger and the flushing station in a common housing and to mount the latter at the transfer point or the discharge point to the public water supply network, e.g. in the apartment entrance/exit area.

(25) In the present case, the flushing station is connected at an end section 18 of the warm water line 3 and downstream of the consumers 4a, 4b. The flushing station 2 can also be connected at any other desired location or between the consumers 4a, 4b.

(26) The present invention proposes, in particular, a combination of the flushing station 2 and the continuous flow heater 1, and controlling the flushing station 2 with the control device 12 of the continuous flow heater 1 in order to prevent, for example, limescale deposit from forming in the secondary circuit.

(27) In the present case, the continuous flow heater 1, configured as a plate heat exchanger, is installed in the heat exchanger housing module 11 such that a plane, in which the heat exchanger plate 8 is located, is disposed inclined relative to the direction of gravity. This inclined position of the continuous flow heater 1 makes it possible to reduce the risk of limescale formation. The advantages of the inclined position are described in the European patent application with the application number 16 170 441.6 and the German utility model with the registration reference number 20 2015 003 756, the disclosure content of which is incorporated with this reference into the present application.

(28) At high water temperatures, CO2 is emitted, causing the pH value of the water to rise and limescale to deposit. Undesirable limescale deposit can occur when the water is stagnant, in particular, at water temperatures above 40 C.

(29) Due to the inclined position of the continuous flow heater 1 shown in FIG. 1, faster intermixing takes place with the cold water supplied, which passes through the water supply line 6 into the continuous flow heater 1.

(30) Because the cold water flows into the continuous flow heater 1 on the upper right side shown in FIG. 1 and drops downwardly to the left along the inclined heat exchanger plate 8, whereby intermixing with the warm water on the outlet side occurs. This intermixing leads to the water in the continuous flow heater 1 cooling down, which reduces the limescale deposit.

(31) However, it has now been found that this limescale deposit cannot always be prevented with the intermixing instigated by gravity. For this reason, the present invention proposes that the warm water line 3 be flushed until the water contained in the continuous flow heater 1 is below a predetermined setpoint temperature once tapping warm water from the water line via the consumer is terminated.

(32) When e.g. the continuous flow heater 1 is switched off via the control device 12, for example, by closing the valve 15, since no warm water is tapped and no warm water is required, forced flushing can be carried out via the flushing station 2. The warm water is then withdrawn from the primary circuit of the continuous flow heater 1 via the flushing station 2, and cooling down takes place.

(33) The flushing station 2 can be instructed by the control device 12 of the continuous flow heater 1 to preferably remain in the open state until the temperature is below the critical temperature for limescale deposit. This is preferably a temperature of below 40 C. However, it is not necessary to specifically select the temperature of below 40 C. It is sufficient for the present invention that the control device controls the flushing station 2 in such a way that the warm water line 3 is flushed until the water contained in the continuous flow heater 1 is below a predetermined setpoint temperature.

(34) The present invention thereby prevents or reduces calcification in the continuous flow heater 1.

(35) It is also not necessarily the case that the flushing station 2 is set such that forced flushing is performed during stagnation for the risk of germs forming. For the invention, it is sufficient that at least one flushing is performed to prevent or reduce calcification.

(36) No cold water line is shown in the embodiment of FIG. 1, but the consumers 4 are typically also connected to the cold water line. This is the case, for example, schematically in the second embodiment according to FIG. 3. In the second embodiment, identical elements are designated with the same reference numerals as in the embodiment of FIG. 1. Only the differences to the embodiment according to FIG. 1 shall be explained below.

(37) Instead of the consumers provided in the warm water line 3, (wash basin tap 4a as well as the shower tap 4b), only one shower tap 4b is provided as a consumer in the second embodiment.

(38) In the embodiment according to FIG. 3, a cold water line 19 branching off from the water supply line 6 is additionally illustrated, to which the same shower fitting 4b is connected that is also connected to the warm water line 3.

(39) The flushing station 2 is connected to one end section 20 of the cold water line 19. The flushing station 2 contains two flushing valves 16, which can not be seen in FIG. 3, and which can be actuated separately and independently of the control device 16 of the flushing station 2 in order to force-flush the cold water line 19 or the warm water line 20, respectively.

(40) The cold water line 19 is connected to the water supply inlet 7 such that a cold water line outlet port 21, just like the further connection ports, are arranged to each other in the heat exchanger housing module 11, which leads to easier connectability to pipe segments.

(41) A further pipe section 20, 22, which ensures circulation in the circuit of the heating when the valve 15 is closed or only partially open, is connected to both the heating feed line inlet 9 as well as to the heating return line outlet 10.

(42) The pipe segment 21, which is connected to the heating feed line inlet 9, therefore leads, for example, to heating ribs or heat-consuming elements, and the return from these heating ribs or heat-consuming elements flows through the pipe section 22.

(43) The temperature sensor provided with reference numeral 13 in FIG. 3 is coupled to the control device 12 of the continuous flow heater 1 and measures the temperature at the outlet of the continuous flow heater in the primary circuit. This makes it easier to determine whether a predetermined temperature has been reached after forced flushing.

(44) FIG. 2 illustrates a perspective side view of an exemplary plate heat exchanger 110 with an inlet 111 and an outlet 112 of a primary circuit 113, an inlet 114 and an outlet 115 of a secondary circuit 116, and a plate 117 indicated as a dot-dashed line which separates the two circuits 113, 116 from each other.

(45) The plate 117 separates the interior of a housingmarked with reference numeral 118of the plate heat exchanger 110 into two compartments 119, 120. The compartment 119 is the flow region for the fluid flowing in the primary circuit. In the compartment 120, the fluid of the secondary circuit 116 flows through the housing 118. As is evident, the inlet 111 of the primary circuit and the outlet 115 of the secondary circuit are located at the bottom edge of the housing 118 near an edge which is defined by a front end of the housing 118. The outlet 112 of the primary circuit and the inlet 114 of the secondary circuit are located at the opposite end of an underside of the housing 118. This underside is defined by a side wall 121 of the housing 118. The compartment 119 for the primary circuit 113 is at the upper side defined by an upper side wall 122 of the housing. This upper side wall 122 of the housing is at its upper end near the front side provided with two vent valves 123, 124. It is understood that a plurality of compartments of the kind described above can be arranged in the plate heat exchanger above each other and alternatingly. Only one compartment was illustrated, namely enlarged, to express more clearly the nature of the invention. The respective compartments are at the end side in communication with the inlets 111, 114 and outlets 112, 115, respectively.

(46) The horizontal is in FIG. 2 indicated by line H. The inclination of the housing, i.e. the walls 121, 122 provided in parallel relative to this horizontal H, is marked by angle . Presently, =35. Also the plate 117 is inclined relative to the horizontal H at a respective angle. Perpendicular thereto, G indicates the gravitational field of the earth. The plate 117 separating the compartments has a surface normal N which runs at the same angle relative to vector G of the gravitational field of the earth.

(47) FIG. 2 shows the installation situation with the connection lines which are connected to respective lines for warm potable water (TVWV), for cold potable water which is provided by the domestic connection (TWK HA), for heating water (Hzg.), where VL depicts the feed and RL the return. The heating pipes with the further index Whg. are connected to the apartment and are the feed and return lines for the house unit. The corresponding lines are numbered with reference numerals 201 through 207. A line 208 connects the inlet 114 of the secondary circuit for potable water of the plate heat exchanger 110 to a branch-off, to which also the lines 202 and 203 are connected. The outlet of the secondary circuit 115 is connected to the line 201. The inlet of the primary circuit 111 is connected via a T-piece to the line 204 for the heating feed. The outlet 112 of the primary circuit is in communication via the line 209 and a three-way valve with the line 205 for the heating return, which can also be connected via the three-way valve to the heating return line 207 coming from the apartment. The lines 205 and 204 carry the heating water via a heating boiler, not shown, in which the heating water is heated.

(48) The conceivable installation situation of the plate heat exchanger in the plate heat exchanger system shown in FIG. 2 is thereby exemplified. This installation situation corresponds to the situation of the second exemplary embodiment shown in FIG. 3.

(49) The flow arrows drawn in in FIG. 2 indicate the circulation caused by free convection after switching off any flow caused by forced convection, which results in rapid temperature equalization within the heat exchanger, namely, due to the inclined orientation of the walls defining the individual compartments 119, 120. The quite cold fluid of the primary circuit 113 located relatively far at the top has a higher density than the slightly warmer fluid of the same circuit 113 located therebeneath. The same applies for the relatively cold fluid of the secondary circuit 116 disposed in the region of the inlet 114 in relation to the fluid of the same circuit located close to the outlet 115. The colder fluid has a stronger tendency to descend due to the higher density. When descending, it presses the relatively warm fluid of the same compartment 119 or 120 upwardly. This results in a micro-circulation due to the different densities which only reaches a standstill when the temperature within the compartments is substantially equalized. Faster temperature equalization and thereby less calcification therefore arise with the solution according to the invention.

(50) In FIG. 2 at the height of the plate 117, the latter's length L and its width B are marked in the form of direction vectors. Direction vector L there denotes the direction of the greatest extension, i.e. the extension in length of the plate 117, and vector B denotes the direction of the extension of the plate in the second greatest direction, i.e. the width direction. Vectors L and B presently span a plane E to which the surface normal N is oriented orthogonally. The presently flat plate 117 is there located entirely within this plane E and itself defines this plane E.

(51) FIG. 4 shows an example of a system of floor lines and riser lines, to the ends of which a flushing valve 330 is connected The flushing valve 330 from the example of FIG. 4 can be integrated into or form the flushing station 2 (not shown in this figure). The example illustrated in FIG. 4 illustrates a potable or tap water installation by way of the example of a hotel or hospital. Several vertical riser lines 302.1, 302.2, 302.3 are there provided, from which ring lines 310 branch of to the individual floors.

(52) The branch-off 314 and the return 316 of the respective ring line 310 are provided on a common ring line flushing fitting 344, which is designed as a branch-off and connection fitting. The ring line can be flushed with the ring line flushing fitting 344 due to a pressure difference prevailing in the riser lines. Further details of the system shown in FIG. 4 are described in the European patent application EP 1 845 207 A1, the disclosure content of which is incorporated by reference into the present application.

(53) For example, instigated by the tapping of warm water, the flushing station 2 in the system shown in FIG. 4 can be controlled by way of the control device 12 of the continuous flow heater 1 (not shown in this example). continuous flow heater 1 flushing station 2 warm water line 3 consumer 4 wash basin tap 4a shower tap 4b warm water outlet 5 water supply line 6 water supply inlet 7 heat exchanger plate 8 heating feed line inlet 9 heating return line outlet 10 heat exchanger housing module 11 control device for the heat exchanger 12 temperature sensor 13 continuous flow sensor 14 valve 15 control device for the flushing station 16 flushing station housing module 17 end section 18 cold water branch-off 19 end section 20 pipe section 21, 22 flushing valve 25, 330 waste water port 26 plate heat exchanger 110 inlet of the primary circuit 111 outlet of the primary circuit 112 primary circuit 113 inlet of the secondary circuit 114 outlet of the secondary circuit 115 secondary circuit 116 plate 117 housing 118 compartment 119, 120 lower side wall of the housing 121 upper side wall of the housing 122 vent valves 123, 124 ring line 310 branch-off 314 return 316 ring line flushing fitting 344 riser lines 302.1, 302.2, 302.3