GB2543868A

GB2543868A - Drinking water heater

Info

Publication number: GB2543868A
Application number: GB1605015.5A
Authority: GB
Inventors: Hecking Willi
Original assignee: Hans Sasserath GmbH and Co KG
Current assignee: Hans Sasserath GmbH and Co KG
Priority date: 2015-10-26
Filing date: 2016-03-24
Publication date: 2017-05-03
Anticipated expiration: 2036-03-24
Also published as: GB201605015D0; GB2543868B

Abstract

A drinking water heater 10 comprising a heatable, closed reservoir 12 for the water 22 to be heated; an inlet 16 for re-filling drinking water; and an outlet channel 26 for hot water. An air cushion 24 is provided inside the reservoir 12 above the water surface, said air cushion for receiving expansion water. The heater is characterized by a tapering 50 of the outlet channel 26 in the range below the water surface 20; an air inlet channel 34 connected to the atmosphere which extends to the range of the tapering (fig. 2, 50) of the outlet channel; and an air separator (fig. 2, 80) for separating air entering the water through the air inlet channel 34. The heater may have a valve assembly controlling the transfer of air from the air separator to the air cushion.

Description

Drinking Water Heater

Technical field

The invention relates to a drinking water heater comprising (a) a heatable, closed reservoir for the water to be heated; (b) an inlet for re-filling drinking water; and (c) an outlet channel for hot water the inlet side end of which ends below the water surface in the water; wherein (d) an air cushion is provided inside the reservoir above the water surface for receiving expansion water.

The drinking water heater essentially consists of a closed container (reservoir) filled with water. The container normally has an inlet provided at its lower end. Cold drinking water is filled into the container through the inlet. An electric heating coil or a heat exchanger with hot water flowing therethrough heats the water in the drinking water heater. The hot water is available at an outlet. If hot water is tapped fresh drinking water is re-filled through the inlet.

Prior Art

If water is heated in a drinking water heater is will expand. The expansion water generated in such a way can be disposed of through a safety valve to a drain. The water is lost in this case. It is, therefore, known to use expansion vessels. Such expansion vessels accommodate expansion water and return the water if possible. It is disadvantageous, however, that expansion vessels have a high volume. Its installation requires much efforts and the devices are relatively expensive.

On the internet site www.megaflo.com, for example, the enterprise Heatrae Sadia sells drinking water heaters with an air cushion under the tradename "Megaflo". The air cushion is provided in the same volume as the heated drinking water. A floating separating plate separates the air cushion from the water. The air cushion enables the expansion of the water without activating the safety valve. The air cushion of the known assembly must be re-filled with air on a regular basis. GB 2 431 461 A and GB 2 413 623 A describe drinking water heaters with an air cushion for internal expansion without a separating plate. A valve with a venturi-jet is provided in the cold water inlet for re-filling the air cushion. Air is uncontrollably entered into the installation and thereby into the air cushion through such a jet. It is disadvantageous with such assembly that the air comprised in the installation will cause an unregular water flow at the tap. Furthermore, air is undesirable in the installation due to its high oxygen content, because oxygen promotes corrosion of the installation.

Disclosure of the invention

It is an object of the invention to provide a drinking water heater of the above mentioned kind where the air cushion is automatically re-filled with air without the disadvantages known from the prior art. According to the invention this object is achieved by (e) a tapering of the outlet channel in the range below the water surface; (f) an air inlet channel connected to the atmosphere which extends to the range of the tapering of the outlet channel; and (g) an air separator for separating air entering the water through the air inlet channel.

The tapering in the outlet channel forms a venturi jet in the air inlet channel. Each time when water is tapped water will flow with an increased velocity through the tapering. Due to the venturi effect air from the air inlet channel is dragged with it. The added air is separated from the hot water afterwards. Contrary to known assemblies air is not uncontrollably added to the cold water, but to the hot water. The added air is guided through an air separator. Air bubbles are formed therein which rise upwards. The air is separated from the water. It is advantageous with such an assembly that the air can be better separated from the water with an air separator in hot water.

The assembly according to the present invention preferably is provided with a valve assembly controlling the transfer of air from the air separator to the air cushion. If the valve is closed no water can flow against the air bubble flow into the air separator and towards the outlet channel. Thereby, the venturi effect at the tapering is secured with a closed valve. If the valve is opened air can be released from the air separator. It is sufficient if the valve opens from time to time. In this case air will be accumulated before the valve until it opens the next time.

Preferably, the valve assembly operates depending on the air volume before the valve. If the collected amount of air increases the water level before the valve will decrease. Then the valve will open. Air will flow out through the open valve. It rises and re-fills the air cushion in the container. If the air is completely gone, the water level before the valve decreases again. The valve will then close. Since the container is closed the air cushion above the water level has always the same pressure as the water. Accordingly, the valve is always pressure compensated.

An air separator can have various shapes and forms. Sieves, baffles for deflecting the flow or labyrinths are well known air separators. It is important that air bubbles can be formed from the air comprised in the water which will rise upwards if they have a sufficient size.

Preferably, it is provided that the valve assembly controls a connecting channel between the range below the water surface and the air cushion. The air is collected in an air chamber before the valve in the connecting channel and is released towards the air cushion if the valve opens. It is, however, also possible that the air separator is positioned in its own chamber which is connected to the air cushion.

In particular, it can be provided that the connecting channel is tube-shaped and integrated in the outlet channel under the water surface and forming an angle with the outlet channel. The angular assembly enables a straight connecting channel which directly connects the range below the water surface to the air cushion. It is understood, however, that the angle between the vertical and the main axis of the connecting channel must be smaller than 90°, preferably in the range between 10° and 80° and most preferably between 40° and 50°. A large angle requires a very large diameter of the reservoir and a small angle limits the diameter of the connecting channel.

In an embodiment of the invention which can be produced with particularly little costs a floater is provided as a valve closing body, which opens and closes an outlet opening of the connecting channel depending on the amount of air in the connecting channel. The connecting channel may be provided with a rim inwardly projecting at its upper end, which forms a valve seat of the valve assembly and cooperating with a swimming ball forming a valve closing body of the valve assembly. The ball always floats at the water surface. If the amount of air increases and the water level decreases the ball is moved downwards in the connecting channel. Then the ball moves away from the inwardly projecting rim. The valve opens. If the water level increases the ball is moved upwards in the connecting channel. Then, the ball is pushed towards the inwardly projecting rim. The valve closes. If the valve is closed the venturi effect will occur at the tapering and new air is added to the water.

The connecting channels serves as a guide for the movement of the ball. It can have an inwardly projecting rim or a shoulder which is slightly lower. This will limit the downward movement.

In a preferred modification of the present invention the valve assembly comprises a plurality of connecting channels with the respective floater. The air is then distributed on a plurality of connecting channels. For example, two opposite connecting channels can be provided. It is, however, also possible to provide 3, 4 or even more connecting channels.

In a preferred embodiment of the invention it is provided that the air separator has at least one deflecting element in the flow in the outlet channel downstream of the tapering The deflecting element then forms the air separator. The deflecting element may be provided with legs extending into the connecting channels whereby the flow is guided through a portion of the connecting channels. Such deflection effects that air bubbles are formed which rise upwards inside the connecting channels. In such a way the air is removed from the water and water with little air content flows to the outlet channel.

In a preferred embodiment of the invention it is provided that the air inlet channel is provided with a backflow preventer opening in the direction of the outlet channel. The backflow preventer prevents that water flows out through the air inlet channel. Air flowing in the opposite direction into the assembly due to the venturi effect is passed through.

Furthermore, it can preferably be provided that the air inlet channel is provided with a failure valve with a floater which closes the air inlet channel upon rising water. The floater closes the air inlet channel so that no water can flow out even upon failure of the backflow preventer. A particularly preferred embodiment of the invention comprises (a) a bypass bypassing the tapering, (b) a backflow preventer positioned inside the bypass and opening in the direction of the outlet; and (c) a tapering with a diameter selected in such a way that the air volume entering at the outlet channel with a selected tapping volume corresponds to a selected target value.

In such an assembly different states can be distinguished: Small amounts of hot water exclusively flow through the tapering. The amount of water is not sufficient to overcome the flow resistance of the backflow preventer created by the spring. The amounts are so little that no or only a very small venturi effect is caused. Accordingly, only very little air is added to the air cushion. A larger flow volume of water will also flow entirely through the tapering. A venturi effect occurs. Air is added to the air cushion. Very large flow volumes which are caused by large tapped amounts of water will cause the backflow preventer to open. In this case a portion of the water flows through the tapering and the remainder of the water will flow through the bypass with the backflow preventer. The flow volume passing the tapering drags air with it while the flow volume through the bypass remains unchanged.

With such an assembly it can be achieved by suitable selection of the diameters of the tapering and the flow resistance of the backflow preventer that the air cushion remains about the same size even if flow volumes flow the added up amount of which is larger than needed to add the required amount of air.

Modifications of the invention are subject matter of the subclaims. An embodiment is described below in greater detail with reference to the accompanying drawings.

Brief description of the drawings

Fig. 1 is a cross sectional view of a drinking water heater with an air cushion.

Fig.2 is a cross sectional view of an air separator with an air inlet and separator for air to flow into the air cushion of the drinking water heater of Figure 1 with a closed valve.

Fig.3 corresponds to Figure 2 with an open valve.

Fig.4 shows the backflow preventer in the air inlet channel in greater detail.

Fig.5 corresponds to Figure 3, but wherein the air cushion extends into the range of the air separator.

Fig. 6 shows the outer end of the air inlet channel with closed backflow preventer for an assembly of Figure 1 in greater detail.

Fig.7 shows the outer end of the air inlet channel with open backflow preventer for an assembly of Figure 1 in greater detail.

Fig. 8 shows an air separator similar to the one in Figure 2 according to a second embodiment with a backflow preventer in a bypass along the air inlet.

Fig.9 shows the air separator of Figure 8 with an open valve.

Description of the embodiment

Figure 1 shows a cross section of a drinking water heater generally designated with numeral 10. The drinking water heater comprises a closed container (reservoir) 12. The container 12 is closed by a lid 14. The container 12 is a pressure vessel and can accommodate high pressures, such as, for example, 3 to 6 bar, as the typically occur in water installation.

Fresh drinking water enters the container 12 through an inlet channel 16. This is illustrated by an arrow 18. Generally, the drinking water is cold. The inlet channel 16 is arranged in the lower third of the container 12.

The container 12 is filled with water 22. The water surface is designated with numeral 20. The container 12 is not entirely filled up. Accordingly, an air cushion 24 is formed above the water surface 20. The pressure in the air cushion 24 is the same as the water pressure.

An outlet channel 26 extends from a range below the water surface 20 through the lid 14 to the installation. Water enters the outlet channel 26 at a lower inlet side end. This is illustrated by an arrow 30. Hot water is available for tapping and for further use at their upper end. This is illustrated by an arrow 28. A heating coil 32 extends in the inside of the container 12. The heating coil 32 operates electrically or a hot medium, such as water, flows through the coil. The heat generated by the heating coil 32 is transferred to the water 22 in the usual way. If the water 22 is heated is will expand. Then the water level formed by the water surface 20 will rise upwards. The air cushion 24 should be always large enough to prevent water from exiting through the safety valve. A small portion of the air is dissolved in the water. Accordingly, the air cushion becomes smaller in the course of the time. Air must be regularly re-filled. An air inlet channel 34 is provided for this purpose. An outer end 36 of the air inlet channel 34 extends into the atmosphere. The position of such end 36 can be almost anywhere. The end is provided on the side of the container 12 in the representation in Figure 1. It is, however, also possible to extend the air inlet channel 34 through the lid, for example, and to position the end 36 above the lid.

The outer end 36 of the air inlet channel 34 is provided with a backflow preventer 38. This is represented in Figures 4, 6 and 7 in greater detail. The spring-biased backflow preventer 38 blocks towards the outside so that no water can exit through the air inlet channel 24 towards the outside. The backflow preventer 38 is arranged in a housing 40 which closes the outer end 36 of the air inlet channel 34. The housing 40 has two portions and is provided with an inwardly projecting rim 42 at its upper end. The rim 42 forms a valve seat cooperating with a floater 44 acting as a valve closing body. The valve comprised of the rim 42 and the floater 44 secures that no water can flow out of the assembly even upon failure of the backflow preventer 38. If water rises in the air inlet channel, the floater 44 is pushed upwards into the valve seat 42. The valve will close.

Figure 2 and Figure 3 illustrate the range of the inner end 46 of the air inlet channel 34. The inner end 46 of the air inlet channel 34 ends in an air adding fitting 54 at the lower end 48 of the outlet channel 26. The outlet channel 26 is tapered in such range 50. If hot water 22 is tapped with closed air adding fitting 54 water will flow through the outlet channel 26. The flow through the outlet channel 26 has an increased velocity in the tapered range 50. Due to the venturi effect air from the air inlet channel 34 is sucked in the direction of the arrow 52. It then enters the hot water at the lower entrance end of the outlet channel 26.

An air separator of the air adding fitting 54 is provided above the tapering 50. The air adding fitting 54 has a vertical outlet channel 26. Furthermore, two connecting channels 56 and 58 are branched off. In the present embodiment two such connecting channels 56 and 58 are provided. It is, however, also possible to use only one or even more connecting channels. The connecting channels 56 and 58 extend upwards at an inclined angle of about 45° relative to the vertical direction. In the present case the connecting channels 56 and 58 are formed by a socket at the lower end which is an integral part of the air adding fitting 54. The air adding fitting 54 of the present embodiment is a separate component which is connected to the outlet channel 26 with its upper, outlet-side end. The lower end of the outlet channel 26 is an integral part of the air adding fitting 54.

An essentially tube-shaped valve seat portion 60 and 62, respectively, is screwed onto the sockets 56 and 58 and sealed with sealings 64 and 66 thereby forming an extension of the sockets 56 and 58. An inner shoulder 72 and 74, respectively, is formed thereby. The entire air adding fitting 54 is below the water surface in Figures 2 and 3. The water surface 20 in Figure 5 is in the range of the valve seat portions 60 and 62. The valve seat portions 60 and 62 have an inwardly projecting rim 68 and 70 at their upper end. A ball 76 and 78 floats inside each of the connecting channels 56 and 58. Air which enters the connecting channels in the way described below is accumulates in an air bubble 94 in the upper range of the connecting channels. Accordingly, the balls 76 and 78 float on the such formed water surface 92 inside the connecting channels 56 and 58.

Due to the buoyancy the balls 76 and 78 are moved upwards and pushed against the rim 68 and 70 of the respective valve seat portion 60 and 62. The valve formed in such a way closes. This situation is illustrated in Figure 2. If air 94 accumulates and the inner water level 92 decreases the balls 76 and 78 are moved downwards. The valve opens for a short period of time. This situation is illustrated in Figure 3. The air is released upwards and fills the air cushion 24. Then the valve will close again. The shoulders 72 and 74 limit the downward movement of the balls 76 and 78. A deflecting element 80 is provided inside the air adding fitting 54 in the range of the sockets of the connecting channels 56 and 58 intersecting the air adding fitting. The deflecting element 80 has two legs 82 and 84. In the present embodiment the legs 82 and 84 of the deflecting element 80 form an angle of 90°. The legs 82 and 84 extend into the lower part of the connecting channels 56 and 58. The deflecting element 80 forms an air separator.

Each time, when hot water is tapped, water flows through the outlet channel 26 in the direction of the arrows 30 and 28. Water enters into the air adding fitting 54 from below. Air is added from the air inlet channel 34 to the closed air adding fitting 54 at the tapering 50 due to the venturi effect. Water enriched with air hits the deflecting element 80. The flow is deflected in the direction of the arrows 86 and 88 around the legs 82 and 84. The flow is merged behind the deflecting element 80 in the outlet channel 26. This is represented by an arrow 90.

Upon deflection the water hits the deflecting element and changes the flow direction. Air bubbles are formed thereby. The air bubbles formed in the connecting channels urge upwards and remain in the connecting channels. In such a way the air is separated from the water. Water flows further in the direction of the arrow 28. The separated air accumulates in the upper range 94 of the connecting channels 58 and 56 below the ball 76 or 78, respectively. This is illustrated in Figure 2. With increasing amount of air the water level 92 decreases. The ball 76 or 78, respectively is moved downwards together with the water level 92. Then air will be released and rise towards the air cushion 24.

In such a way each time, when hot water is tapped with closed air adding fitting air is sucked in and transmitted to the air cushion 24 in a controlled manner. Due to the separation in the air separator air will practically not enter the installation anymore.

The assembly is self-controlling: if sufficient air 94 is accumulated in the connecting channels the water level 92 is in a lower position in the air adding fitting. In this case the valve at the connecting channel is open. The air adding fitting is open and the pressure loss at the tapering 50 is low. There is essentially no venturi effect. If, however, there is only little or no air present below the valve the water level 94 is in an upper position. Then the ball closes the valve and the entire pressure loss is effective at the tapering. In this case there is a strong venturi effect and air is sucked in until the water level is in the position shown in Figure 3.

Since the pressure in the air cushion 24 is the same as the water pressure in the water 22 there are no additional forces acting on the balls. The pressure is compensated on both sides apart from the buoyant forces of the water.

Figure 5 illustrates the case occurring if very much air enters the air cushion 24. The water surface 20 in the container is then in the range of air adding fitting 54. The ball floats on this water surface and the valve is open permanently. If the valve is open practically no venturi effect occurs because the pressure compensation during tapping is effective not only in the direction of the arrow 30 but also through the openings in the valve seat bodies. Therefore, the air cushion 24 is not further increased.

Figures 8 and 9 show an alternative embodiment with an air adding fitting 154. The air adding fitting 154 is almost identical to the air adding fitting 54 described above. It must, therefore, not be described in greater detail here. Contrary to the air adding fitting 54 described above the air adding fitting 154 has not only a tapering 150 at its lower end of the outlet channel 126 but also a bypass 151. The bypass 151 bypasses the tapering with the air inlet channel 134. Therefore, hot water can either flow through the tapering 150 or through the bypass 151 to the outlet channel 126. This is illustrated by arrows 147 and 149. A backflow preventer 153 is provided in the bypass 151. The backflow preventer 153 has a flow resistance and only opens upon sufficient flow volume. The backflow preventer 153 ensures that all water flows through the tapering 150 if only small amounts of water flow through the assembly. Then the venturi effect will occur. With large flow volumes of water a portion of the water flows in the direction of arrow 149 through the backflow preventer and does not absorb any air. In such a way excessive air addition is prevented.

The above embodiments were described in great detail. It is understood, however, that many changes and variations are possible. The air separator, for example, may assume any form. Also, the position of the outer end of the air inlet channel can be selected as it suits the application. Any kind of valve may be used instead of a valve with a floater as long as it opens and closes depending on the water level of the water surface.

Claims

1. Drinking water heater comprising (a) a heatable, closed reservoir for the water to be heated; (b) an inlet for re-filling drinking water; and (c) an outlet channel for hot water the inlet side end of which ends below the water surface in the water; wherein (d) an air cushion is provided inside the reservoir above the water surface for receiving expansion water; characterized by (e) a tapering of the outlet channel in the range below the water surface; (f) an air inlet channel connected to the atmosphere which extends to the range of the tapering of the outlet channel; and (g) an air separator for separating air entering the water through the air inlet channel.

2. Drinking water heater according to claim 1, characterized by a valve assembly controlling the transfer of air from the air separator to the air cushion.

3. Drinking water heater according to claim 2, characterized in that the valve assembly is provided in a connecting channel between the range below the water surface and the air cushion.

4. Drinking water heater according to claim 3, characterized in that the connecting channel is tube-shaped and integrated in the outlet channel under the water surface and forming an angle with the outlet channel.

5. Drinking water heater according to claim 3 or 4, characterized by a floater as a valve closing body, which opens and closes an outlet opening of the connecting channel depending on the amount of air in the connecting channel.

6. Drinking water heater according to claim 5, characterized in that the connecting channel is provided with a rim inwardly projecting at its upper end, which forms a valve seat of the valve assembly and cooperating with a swimming ball forming a valve closing body of the valve assembly.

7. Drinking water heater according to any of the preceding claims 3 to 5, characterized in that the valve assembly comprises a plurality of connecting channels with the respective floater.

8. Drinking water heater according to any of the preceding claims, characterized in that the air separator is provided with at least one deflecting element in the flow in the outlet channel downstream of the tapering.

9. Drinking water heater according to claim 3 and 7, characterized in that the deflecting element is provided with legs extending into the connecting channels whereby the flow is guided through a portion of the connecting channels.

10. Drinking water heater according to any of the preceding claims, characterized in that the air inlet channel is provided with a backflow preventer opening in the direction of the outlet channel.

11. Drinking water heater according to claim 10, characterized in that the air inlet channel is provided with a failure valve with a floater which closes the air inlet channel upon rising water.

12. Drinking water heater according to any of the preceding claims, characterized by (a) a bypass bypassing the tapering, (b) a backflow preventer positioned inside the bypass and opening in the direction of the outlet; and (c) a tapering with a diameter selected in such a way that the air volume entering at the outlet channel with a selected tapping volume corresponds to a selected target value.

13. A drinking water heater substantively as herein described with reference to the accompanying drawings.