Water heater and method for determining an emptying state of a section of a pipeline of a water heater

Abstract

The invention relates to a water heater (100) having a water tank (10), a heat exchanger (11) and a pipeline (12) connected to a pump device (13) and to the water tank, such that water (14) heated by means of the heat exchanger (11) can be conducted into the water tank (10), wherein the water heater (100) is designed as a combination heater by means of which a hot water heating mode and a room air heating mode can be combined. According to the invention, the water tank (10) can be filled with water (14) up to a maximum fill level (H) such that in the filled state an air bubble (15) is produced above the maximum fill level (H), the pumping direction of the pump device (13) can be reversed, and the pipeline (12) opens into the water tank (10) above the maximum fill level (H) via an upper connection (16) and below the maximum fill level (H) via a lower connection (17) such that, during pumping in a first pumping direction, water (14) is pumped to the upper connection (16) and, during pumping in a second pumping direction, the pipeline (12) is emptied between the upper connection (16) and the pumping device (13). The invention further relates to a method (200) for determining an emptying state of the section of the pipeline (12) between the upper connection (16) and the pump device (13).

Description

[0001] Water heater and method for determining a drain condition of a section of a water heater pipe

[0002] The invention relates to a water heater, in particular a water heater for a mobile living facility, comprising a water tank, a heat exchanger and a pipe which is connected to a pumping device and the water tank in such a way that water heated by the heat exchanger can be fed into the water tank, wherein the water heater is designed as a combination heater with which a hot water heating operation and a room air heating operation can be combined.

[0003] Furthermore, the invention relates to a method for determining an emptying state of a pipeline of such a water heater in a section between an upper connection of the water tank and the pumping device.

[0004] Water heaters of the type discussed here are used particularly in mobile living facilities, such as mobile homes or caravans, to provide heated water and heat the air within the facility. For example, DE 10 2021 005 383 A1 discloses a device of this type.

[0005] The piping of such a water heater is usually directly connected to the heat exchanger along one section, so that the heat generated there is transferred to the circulating water. If the water remains stationary within the piping for an extended period of time, for example when no water is being drawn off at any given time, the water absorbs excessive heat, particularly during room air heating mode, causing an excess of limescale to deposit, which collects on the walls of the piping, inside the pump, and inside the water tank. Due to its low thermal conductivity, the deposited limescale reduces the efficiency of the heat exchanger and, over time, also negatively impacts the functionality of the pump. The deposited limescale must therefore be removed by the user at regular and short intervals through complex descaling.Furthermore, evaporating water creates excess pressure within the system, which is also difficult to regulate. Based on this, the object of the invention is to propose a water heater and a method that can eliminate the disadvantages of the prior art. In particular, it should be possible to reduce limescale formation and avoid periods of excess pressure in the system in a simple manner.

[0006] This object is achieved by the water heater according to claim 1 and the method according to claim 8.

[0007] According to the invention, it is initially provided that the water tank can be filled with water up to a maximum fill level, so that when filled, an air bubble is created above the maximum fill level, the pumping direction of the pumping device is reversible and the pipeline opens into the water tank above the maximum fill level via an upper connection and below the maximum fill level via a lower connection, so that when pumping in a first pumping direction, water is pumped to the upper connection and when pumping in a second pumping direction, the pipeline between the upper connection and the pumping device is emptied. This allows water that is stationary within the pipeline to be directed into the water tank and replaced by air from the air bubble.This prevents water from being heated / heated within the pipes during room air heating operation, resulting in less limescale buildup and no increase in pressure due to evaporation. This also means that the user only needs to carry out the time-consuming descaling of the system at comparatively longer intervals.

[0008] Advantageous embodiments of the water heater according to the invention are specified below and in the subclaims.

[0009] Preferably, a heater is provided that supplies the heat exchanger with hot air by means of a fan / blower and a burner. The heat exchanger forms part of the heater. Such a burner can be designed, for example, as a gas burner that burns gases such as propane, butane, or gaseous diesel or gasoline fuel. The heater can have additional electrical heating elements, which can be integrated, in particular, into the heat exchanger. As an alternative to a burner, an electrical heating device can also be provided.

[0010] Preferably, the pumping device for reversing the pumping direction comprises a pump configured to reverse the pumping direction upon a reversal of the direction of rotation, wherein the pump is preferably designed as a peripheral impeller pump, side-channel pump, or gear pump. Such an embodiment is particularly space-saving and therefore advantageous because additional piping and / or pumps can be eliminated.

[0011] Irrespective of this, in a first alternative embodiment, it is preferably provided that the pumping device for reversing the pumping direction has two pumps whose pumping directions are aligned antiparallel to one another.

[0012] Alternatively, in a second embodiment, it is preferably provided that the pumping device for reversing the pumping direction comprises a single pump with a valve-controlled bypass line circuit. The valve-controlled bypass line preferably has a 3 / 2-way valve, two shut-off valves, and two bypass lines arranged such that the pumping direction of the water within the pipeline is reversible while maintaining a constant flow direction of the pump.

[0013] According to an advantageous development of the invention, the water tank has a water dispensing connection below the maximum fill level. The water dispensing connection is preferably located in the upper half, particularly in the upper third, of the water tank, so that warm water can be dispensed without having to heat the entire water tank.

[0014] Preferably, the pipeline is connected to a water supply line in a section between the pumping device and the lower connection.

[0015] The pipeline preferably has a shut-off valve between the heat exchanger and the pump, which is designed as a "normally open" valve (normally open when de-energized) or a "normally closed" valve. Once the pipeline is drained in the section between the upper connection and the pumping device, the shut-off valve is closed to prevent unwanted water from flowing back into the section of the pipeline between the pumping device and the upper connection.

[0016] The heat exchanger is advantageously designed as a finned heat exchanger, wherein the finned heat exchanger has a body which receives the pipe in sections and is connected to fins, wherein the body is preferably made of aluminum and in particular is designed as a die-cast aluminum.

[0017] A control and evaluation unit is provided to control the water heater, with which the operating parameters of the pumping device and the switching positions of any valves are adjusted as needed. This means that the control and evaluation unit is designed to control the pumping device and, preferably, any valves.

[0018] A further aspect of the invention relates to a method for determining a draining state of the section of the water heater's pipeline in the section between the water tank and the pumping device, comprising the following steps: operating the pumping device in a pumping direction to drain the pipeline, measuring the pump flow as a function of time, comparing the measured pump flow or a variable derived from the pump flow with a predetermined draining limit, and determining sufficient draining if the measured pump flow or the variable derived from the pump flow falls below the predetermined draining limit. If the measured pump flow or the variable derived from the pump flow is equal to or exceeds the draining limit, insufficient draining is determined.

[0019] To measure the pump current, a current sensor can be assigned to the pumping device. To measure the pump current, the pump current is preferably sampled at discrete, equidistant times during operation of the pumping device for emptying. The interval between these sampling times is also called the sampling interval. The process steps in which the measured pump current is compared with the emptying limit value and sufficient or insufficient emptying is determined—and thus a draining state (also called draining quality) is determined—can be carried out by the control and evaluation unit. The draining limit value is particularly system-dependent and is stored in the control and evaluation unit.

[0020] If insufficient emptying and thus inadequate emptying quality is detected, a request signal is preferably provided to a user / operator to (re)establish the air bubble by manually draining water from the container or to enlarge an existing but too small air bubble. Alternatively or additionally, automatic drainage at the water outlet connection is performed by the control and evaluation unit.

[0021] According to a preferred embodiment of the method according to the invention, an average value, for example the arithmetic mean, is calculated from the pump current measured during operation of the pump device. A moving average is particularly preferably calculated, so that the measured current value is advantageously smoothed and the influence of outliers can be minimized. The average value of the pump current represents the aforementioned quantity also calculated from the measured pump current. The averaging can be performed by the control and evaluation unit.

[0022] Specific embodiments of the invention are explained below with reference to the figures. They show:

[0023] Fig. 1a is a block diagram of a water heater;

[0024] Fig. lb shows a detailed view of a first alternative pumping device;

[0025] Fig. lc is a detailed view of a second alternative pumping device;

[0026] Fig. 2a is a flowchart of a method;

[0027] Fig. 2b is a diagram. Fig. 1a shows a block diagram of a water heater 100 of a mobile living facility with a water tank 10, a heat exchanger 11, and a piping 12. The water heater 100 is also referred to below as the "system."

[0028] The pipe 12 is connected to a pumping device 13 and the water tank 10 in such a way that water heated by the heat exchanger 11 can be fed into the water tank 10. The water heater 100 is designed as a combination heater with which hot water heating operation and room air heating operation can be combined. The water tank 10 can be filled with water 14 up to a maximum fill level H, so that when the water tank 10 is filled, an air bubble 15 is formed above the maximum fill level H. In the illustrated embodiment, the water tank 10 has a capacity of 5 l of water and 0.8 l of air.The pumping direction of the pumping device 13 is reversible, and the pipe 12 opens into the water tank 10 above the maximum fill level H via an upper connection 16 and below the maximum fill level H via a lower connection 17, so that when pumping in a first pumping direction, water 14 is pumped to the upper connection 16, and when pumping in a second pumping direction, the pipe 12 between the upper connection 16 and the pumping device 13 is emptied. In this case, the pipe 12 in the section between the upper connection 16 and the lower connection 17 has, for example, a capacity of 90 ml. The water heater 100 has a heater 18, which supplies the heat exchanger 11 with hot air by means of a fan / blower 19 and a burner 20.

[0029] In the illustrated embodiment, the water tank 10 has a water extraction connection 21 below the maximum fill level H. Furthermore, the pipe 12 is connected to a water supply line 22 in a section between the pumping device 13 and the lower connection 17, so that extracted water can be refilled. The illustrated heat exchanger 11 is designed as a finned heat exchanger 111, wherein the finned heat exchanger 111 has a body 23 that accommodates the pipe 12 in sections and is connected to fins 24. The body 23 is made of aluminum in the form of an aluminum die-casting, into which the pipes 12 are embedded, in particular as stainless steel pipes. Various specific embodiments are provided for reversing the pumping direction. Fig.Figure 1a shows an embodiment according to which the pumping device 13 for reversing the pumping direction comprises a single pump 25, which is configured to reverse the pumping direction upon a reversal of the direction of rotation. For this purpose, the pump 25 shown is designed as a peripheral impeller pump 251. The pipeline 12 has a shut-off valve 26 between the heat exchanger 11 and the pump 25, which is designed as a "normally open" valve. As soon as the pipeline 12 is emptied in the section between the upper connection 16 and the pumping device 13, the shut-off valve 26 is closed so that water does not undesirably flow back into the section of the pipeline 12 between the pumping device 13 and the upper connection 16.

[0030] Fig. lb shows a first alternative embodiment, according to which the pumping device 13 for reversing the pumping direction has two pumps 25 whose pumping directions are aligned antiparallel to each other.

[0031] Fig. 1c shows, in two different settings, a second alternative embodiment of the pumping device 13, in which the pumping device 13 has a single pump 25 with a valve-controlled bypass line circuit TI for reversing the pumping direction. The valve-controlled bypass line circuit TI comprises a 3 / 2-way valve 28. A pipe section 29 branches off from this to the pump 25. The pipe section 29 is connected to the lower outlet 17 of the water tank 10 via a shut-off valve 30. Furthermore, a first bypass line 31 branches off from the 3 / 2-way valve 28 and opens into the pipe section 29 between the pump 25 and the first shut-off valve 30. A second bypass line 32 with a second shut-off valve 33 branches off from the pipe section 29 between the 3 / 2-way valve 28 and the pump 25 and opens into the pipe section 29 between the first shut-off valve 30 and the lower outlet 17 of the water tank 10.As a result, the pumping direction of the water within the pipeline 12 is reversible depending on the valve settings, as symbolized by the unnumbered arrows, while maintaining a constant flow direction of the pump 25. The bypass line circuit TI comprises, in particular, the first bypass line 31, the second bypass line 32, the 3 / 2-way valve 28, and the second shut-off valve 33.

[0032] Fig. 2a schematically shows a flow diagram of a method 200 for determining an emptying state of the section of the pipeline 12 of the water heater 100 between the upper connection 16 of the water tank 10 and the pumping device 13. First, the pumping device 13 is operated in a pumping direction for emptying the pipeline 12 (step 50). The pumping direction for emptying corresponds to the pumping direction in which the water flows from the upper connection 16 toward the pumping device 13. The pumping current I is measured as a function of time t (step 51). The pumping current I is measured in particular by means of a current sensor (not shown) assigned to the pumping device 13. In a subsequent step 52, the measured pumping current I is compared with an emptying limit value stored in the control and evaluation unit 34.Preferably, in step 52, an average value, in particular a moving average value, is formed from the pump current I measured during pump operation for emptying, and this average value is compared with the emptying limit value.

[0033] If it is determined in the subsequent step 53 that the average pump current I falls below the emptying limit, sufficient emptying / adequate emptying quality is determined as the emptying state, and the method ends in step 54. If, however, it is determined in step 53 that the average pump current I exceeds or is equal to the emptying limit, insufficient emptying / insufficient emptying quality is determined as the emptying state, and in the subsequent step 55, a request signal is sent to the operator / user to restore or enlarge the air bubble 15 by manually draining water from the water extraction connection 21. Alternatively, the control and evaluation unit 34 initiates an automatic draining of water from the water extraction connection 21 by appropriately controlling the water extraction connection 21.

[0034] Fig. 2b illustrates the evaluation of the pump current I in two different cases. After the start of the emptying process, a waiting period dt0 preferably starts, during which no pump current measurements need to be taken due to the system-inherent delay time, thus saving storage capacity. Thereafter, during the remaining duration of the emptying process dt, the pump current I is recorded / measured at specific measuring intervals / sampling intervals (step 50). Depending on the size of the existing air bubble 15, the measurement curves Kn or K2I result. Subsequently, the moving average is determined as a value formed from the pump current I, from which the mean value curves K i2 and K 22 Based on the mean curves K i2 and K 22The evaluation of the emptying or the emptying quality takes place at the end of the period dt by checking whether the specified emptying limit value W has been undercut. The emptying limit value W can, for example, be stored in the control and evaluation unit 34. If the mean value is below the emptying limit value W (mean value curve K i2 ), the emptying / emptying quality is sufficient, ie the pipe 12 is sufficiently emptied of water in the section between the upper connection 16 and the pumping device 13. If, on the other hand, the mean value is above the emptying limit value W (mean value curve K 22), the emptying / emptying quality is insufficient, and the user is prompted to restore the air bubble 15. Particularly in the case of incomplete and thus insufficient emptying due to a surging water surface in the water tank, e.g., caused by emptying while driving, the method according to the invention can be used to reliably determine, including evaluate, the emptying status.

[0035] Reference symbol

[0036] 100 water heaters

[0037] 200 procedures

[0038] 10 water tanks

[0039] 11 heat exchangers

[0040] 111 finned heat exchangers

[0041] 12 Pipeline

[0042] 13 Pumping device

[0043] 14 Water

[0044] 15 air bubble

[0045] 16 upper connection

[0046] 17 lower connection

[0047] 18 stokers

[0048] 19 Fan

[0049] 20 burners

[0050] 21 Water extraction connection

[0051] 22 Water supply line

[0052] 23 bodies

[0053] 24 slats

[0054] 25 Pump

[0055] 251 Peripheral impeller pump

[0056] 26 Shut-off valve

[0057] TI valve-controlled bypass line circuit

[0058] 28 3 / 2-way valve

[0059] 29 Pipeline section

[0060] 30 Shut-off valve

[0061] 31 Bypass line

[0062] 32 Bypass line

[0063] 33 Shut-off valve

[0064] 34 Control and evaluation unit

[0065] 50 - 55 process steps

[0066] 200 Procedure- H Filling height

[0067] I pump current t time

[0068] K curves

[0069] W Emptying limit

Claims

Patent claims 1. Water heater (100), in particular a water heater (100) for a mobile living facility, comprising a water tank (10), a heat exchanger (11), and a pipe (12) connected to a pumping device (13) and the water tank (10) in such a way that water (14) heated by the heat exchanger (11) can be conducted into the water tank (10), wherein the water heater (100) is designed as a combination heater with which a hot water heating operation and a room air heating operation can be combined, characterized in that the water tank (10) can be filled with water (14) up to a maximum filling level (H), so that in the filled state an air bubble (15) is formed above the maximum filling level (H), the pumping direction of the pumping device (13) is reversible, and the pipe (12) is connected above the maximum filling level (H) via an upper connection (16) and below the maximum filling level (H) flows into the water tank (10) via a lower connection (17),so that when pumping in a first pumping direction, water (14) is pumped to the upper connection (16) and when pumping in a second pumping direction, the pipeline (12) between the upper connection (16) and the pumping device (13) is emptied.

2. Water heater (100) according to claim 1, characterized in that the pumping device (13) for reversing the pumping direction comprises a pump (25) which is designed to reverse the pumping direction when the direction of rotation is reversed, wherein the pump (25) is preferably designed as a peripheral impeller pump (251), side channel pump or gear pump.

3. Water heater (100) according to claim 1, characterized in that the pumping device (13) for reversing the pumping direction has two pumps (25) whose pumping directions are aligned antiparallel to each other.

4. Water heater (100) according to claim 1, characterized in that the pumping device (13) for reversing the pumping direction comprises a single pump (25) with a valve-controlled bypass line circuit (27).

5. Water heater (100) according to claim 4, characterized in that the valve-controlled bypass line circuit (27) has a 3 / 2-way valve (28), two shut-off valves (30, 33) and two bypass lines (31, 32) which are arranged such that the pumping direction of the water within the pipe (12) is reversible with a constant flow direction of the pump (25).

6. Water heater (100) according to one of claims 1 to 5, characterized in that the pipeline (12) is connected to a water supply line (22) in a section between the pumping device (13) and the lower connection (17).

7. Water heater (100) according to one of claims 1 to 6, characterized in that the pipe (12) between the heat exchanger (11) and the pump (25) has a shut-off valve (26).

8. A method (200) for determining an emptying state of a pipe (12) of a water heater (100) according to one of claims 1 to 7 in a section between the upper connection (16) of the water tank (10) and the pumping device (13), comprising the following steps: Operating (50) the pumping device (13) in a pumping direction to empty the pipeline (12), Measuring (51) the pump current (I) as a function of time (t), Comparing (52) the measured pump current (I) or a variable formed from the pump current (I) with a predetermined emptying limit value, Determining (53) sufficient emptying if the measured pump flow (I) or the variable formed from the pump flow (I) falls below the specified emptying limit value and determining insufficient emptying if the measured pump flow (I) or the variable formed from the pump flow (I) is equal to the emptying limit value or exceeds the emptying limit value.

9. The method (200) according to claim 8, characterized in that a request signal is provided to a user to inflate the air bubble (15) by to establish or increase manual water drainage if insufficient drainage is detected.

10. Method (200) according to claim 8 or 9, characterized in that the variable formed from the pump current (I) is the arithmetic mean of the pump current (I) measured during operation of the pumping device for emptying.

11. Method (200) according to claim 10, characterized in that the variable formed from the pump current (I) is the moving average of the pump current (I) measured during operation of the pumping device for emptying.

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