GB2572465A - Drinking water heater with venting fitting - Google Patents

Abstract

The venting fitting (10, figure 1) is installed in a feed pipe (12, figure 1) of a drinking water heater with an air cushion. The fitting has a housing with a housing interior 102 located between a water inlet 36 and outlet 38. The fitting also has at least one air inlet 42 connected to atmosphere and having an air pressure chamber (134, figure 15) defined between an air inlet valve (e.g. backflow preventer 116) and a moveable lifting element (e.g. piston 108). Movement of the element causes a volume and pressure change in the chamber, with the air inlet valve permitting air to enter the chamber from ambient when the chamber pressure falls sufficiently. A one-way air outlet valve (e.g. grooved ring 130, figure 15) permits air to pass from the chamber into the housing interior and mix with water when the air chamber reaches a pre-set pressure. A drive moves the element. The drive may comprise a turbine wheel 74 that turns when there is water flow through the fitting to move the element back and forth via a gear system. Alternatively, an electric motor may drive the element when water flow through the fitting is sensed.

Description

Drinking water heater with venting fitting

Technical field

The invention relates to venting fitting for drinking water heaters with an air cushion for receiving expansion water, comprising:

(a) a fitting housing with a water inlet and a water outlet and a water filled housing interior arranged between the water inlet and the water outlet, (b) at least one air inlet provided at the fitting housing and adapted to be connected to atmosphere, (c) an inlet valve arranged in the air inlet, limiting an air filled pressure chamber, the pressure thereof acting in a closing direction on the inlet valve, (d) a moveable lifting element limiting the pressure chamber, the movement thereof causing a volume- and pressure change in the pressure chamber whereby the inlet valve is opened or closed; and (e) a direction dependent outlet valve opening upon reaching a set pressure in the air filled pressure chamber.

Furthermore, the invention relates to a drinking water heater with such a venting fitting and a method for operating such a venting fitting. A drinking water heater essentially consists of a closed, water filled container. The container normally has an inlet provided at its lower end. Cold drinking water is inserted 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 provided at an outlet. When hot water is tapped fresh drinking water is fed through the inlet.

Prior Art

When water is heated in a drinking water heater it expands. The expansion water generated thereby can be released through a safety valve into a drain. Water is then lost. It is, therefore, known to use expansion vessels. They will receive the expansion water and will re-fed it if possible. It is disadvantageous, however, that such expansion vessels have much volume. Its installation is difficult and the devices are relatively expensive.

The company Heatrae Sadia sells drinking water heaters with an air cushion under the trade mark Megaflo, for example on the internet at www.megaflO.com . The air cushion is provided in the same volume as the water which shall be heated. A floating separating plate separates the air cushion from the water. The air cushion enables the expansion of water without activating the safety valve. The air cushion of the known assembly must be regularly re-filled.

GB 2 431 461 A and GB 2 413 623 A describe drinking water heaters with an air cushion without a separating plate for internal expansion. A valve with a venturi jet is provided in the cold water feeding pipe for re-filling the air cushion. With such an assembly the air is moved together with the water. Air is uncontrollably inserted into the installation and into the air cushion through the jet. It is a disadvantage with such an assembly that the air comprised in the installation will cause an uneven water flow at the tap. Furthermore, air is not desired in the installation due to its high oxygen content because oxygen promotes the corrosion of the installation.

DE 20 2016 104 365 U1 discloses a drinking water heater with a venting device interior the drinking water heater. A piston is moved when water is tapped and air is inserted through a separate air inlet into the air cushion. The assembly is designed in such a way, that only one lifting movement occurs with each tapping procedure. The installation of the fitting interior the drinking water heater is disadvantageous and requires a separate air inlet.

Disclosure of the invention

It is an object of the invention to provide an improved venting fitting for drinking water heaters with an air cushion. According to the invention this object is achieved with a venting fitting of the above mentioned kind which is characterized in that (f) a drive is provided for moving the lifting element;

(g) the outlet valve is provided between the air inlet and the water filled interior of the housing, whereby air will evaporate into the water filled interior of the housing of the fitting housing if the outlet valve opens; and (h) the water inlet and the water outlet are adapted to be installed in the feeding pipe of a drinking water heater.

The invention provides that air can be inserted into the water filled housing interior of the fitting housing. This enables that the fitting can be installed in the feeding pipe of the drinking water heater and not interior the drinking water heater. This in turn allows easy installation without the need to change the boiler. Also, the exchanging of old, less effective or defect devices is possible.

Preferably, it is provided that the drive comprises a motor. It has been shown that it is particularly simple, if the motor is an electric motor which is feed with energy from an energy source with electric energy. A particularly simple assembly is achieved, if the energy source is formed by exchangeable batteries or accumulators. Then no electric cables are necessary and the assembly can be installed at any desired position.

When using a motor, it is particularly advantageous if (a) a pressure sensor is provided detecting the pressure, the pressure development and/or the pressure drop in the water filled portion of the fitting upon tapping of water; and (b) a control is provided which is fed by the signals of the pressure sensor, the control controlling the drive depending on such signals.

Alternatively the motor is controlled by experience values or other measuring values, such as, for example, the tapping behavior, and air is always inserted into the water filled portion of the venting fitting and thereby into the drinking water heater, if the experience - or measured values indicate that there is not sufficient air present in the drinking water heater. A control by a pressure sensor avoids tolerances and effects always the same water level in the drinking water heater.

The assembly operates particularly advantageously, if an inlet side pressure reducer is provided upstream of the inlet valve. Thereby, a secure pressure level is obtained which is always the same and the pressure drop can be easily determined with one single sensor only. If the air cushion is sufficiently large, a smaller pressure drop occurs than if the air cushion is only small or there is no air cushion at all present. The pressure drop during tapping with a not sufficiently large air cushion can be quickly recognized. In order to avoid that the larger pressure drop is caused by several simultaneous tapping procedures which can cause an error message the measurement can be repeated once or even several times. Only if it is ensured that the large pressure drop is caused by an air cushion which is too small air will be fed into the water filled portion of the venting fitting.

A turbine hydraulically driven by the flow between the water inlet and the water outlet can be used instead of a motor wherein the turbine has a drive outside the flow path and acting on the lifting element. It will then serve as a drive of the piston.

The turbine with such an embodiment of the invention is hydraulically driven by the flow generated when tapping water. The hydraulic force of a flow generated when tapping water is transmitted on the lifting element with the turbine. With the turbine it is possible, that the lifting element carries out more than one stroke. The lifting element carries out a reciprocal movement which continues as long as water is tapped and a flow is generated. Thereby, more air can be generated for the air cushion than it is the case with known assemblies. This is not possible with a flow having a force directly acting on the lifting element as it is the case with the prior art. The flow always acts in the same direction with the known assemblies and, thereby, only enables one single stroke. The turbine will always rotate during tapping. This modification of the invention is only useful for drinking water heaters where the tapping behavior is such that the air loss in the air cushion is just compensated.

For transmitting the force, in particular of a turbine, it is advantageous if a mechanic gear mechanism is provided between the turbine and the lifting element.

In a further modification of the invention it is provided that the inlet valve is a backflow preventer. The backflow preventer is provided for air. It will pass air into the pressure chamber when the pressure drops. Air cannot be released back through the backflow preventer when the pressure increases because it blocks the flow in this direction.

An embodiment is particularly advantageous where the air inlet is provided at a tubeshaped housing socket and the lifting element comprises a piston which is moveably guided in the longitudinal direction in the housing socket. However, different modifications for a pressure chamber may be used which enable a pressure- or volume change.

A compact assembly is achieved if the inlet valve is provided interior the piston. It is, however, also possible to provide the inlet valve at a different position between the pressure chamber and the atmosphere.

In a further modification of the invention it is provided that the piston is provided with a direction dependent outlet valve in the form of a grooved ring where air will pass in the direction of the water filled interior of the housing of the fitting housing when the threshold of the pressure in the pressure chamber is exceeded. A grooved ring is a sealing ring which is provided with an annular groove in a circumferential direction. Water side pressure acts on the entire surface of the grooved ring and presses it apart. No water can flow from the water filled interior of the housing into the air filled pressure chamber. In the other direction the grooved ring is exposed to air pressure. If the differential pressure between air pressure and water pressure exceeds a threshold which depends on the diameters, the form and the material of the grooved ring, the grooved ring is pressed together at its groove. Thereby, the passing of air into the water filled interior of the housing is enabled. The air is released and forms bubbles which rise into the air cushion in the drinking water heater. The grooved ring forms an inexpensive, reliable and easy to install valve. It is understood, however, that any other outlet valve may be used also.

Contrary to the use of a venturi-effect air is released only if the pressure in the pressure chamber exceeds a threshold. Relatively large bubbles are formed thereby. They reach the air cushion practically as a whole. Consequently, oxygen and air damaging the installation is not overly accumulated the water.

In a modification of the invention at least one further air inlet is provided with its own pressure chamber and its own lifting element. Thereby, the introduced amount of air can be increased. In particular, it can be provided that all lifting elements can be driven by the same drive. This is advantageous because the assembly requires relatively little space.

In an embodiment a turbine, for example, can be formed by an impeller tangentially exposed to the flow generated when tapping water.

For transmitting a rotational movement of a motor shaft or a turbine to the lifting member a piston rod or another element for transmitting a rotational movement of the drive to the lifting element can be provided. With the piston rod the rotational movement is converted to a linear movement of the lifting element.

In a further modification of the invention it is provided that the drive drives a shaft exerting a torque on a rotatable element having the end of the piston rod remote from the lifting element eccentrically and rotatable connected thereto. In particular, the rotatable element can be a rotatable disc. The rotatable disc can be provided with a shaft or a pin adapted to rotatably connect to the end of the piston rod. Upon rotation the piston rod and thereby the lifting element is moved back and forth. The assembly forms quasi an air pump.

Preferably, a safety valve is provided in the outlet downstream of the inlet valve. The safety valve opens upon over pressure in the drinking water heater. A safety valve integrated in the venting fitting reduces the time and effort for the installation.

Furthermore it can be provided, that a ball valve or any other shut-off valve is provided in the inlet. Thereby, the incoming flow of the drinking water heater can be shut off, for the purpose of, for example, servicing.

If a motor is used as a drive, air can be introduced at certain times, at night, for example, in one go. It does not matter then, which amount of air is introduced per time unit or per stroke. With assemblies where the amount of the introduced air depends on the tapping number and the tapped volume a compact and efficient assembly is achieved if two air inlets are provided at two coaxial, pipe-shaped housing sockets and the piston rods are rotatably connected to the same point of the rotatable element whereby the movement of the two lifting elements is effected always in the same direction. Such an assembly corresponds quasi to a V-180°-assembly. The compression of the pressure chambers is effected in an alternating rhythm. It is, however, also possible to arrange the piston rods at opposing points. Then a boxer assembly is achieved where the compression is effected simultaneously. In particular, such a linear assembly of the two housing sockets can be arranged in parallel to the pipe. Thereby only little space is required in a radial direction.

It can be provided that the flow path through the fitting housing is divided, wherein a first flow path proceeds through a backflow preventer opening in the flow direction or another flow resistance and the drive of the turbine is provided in a second flow path which is separate from the first flow path. The flow resistance causes the turbine to be driven even with small flows with a sufficient power. In particular it is advantageous if a gear is used which has a transmission ratio larger than 1, preferably larger than 2. The gear is, therefore, a reduction gear. The lifting movement is then smaller than the movement of the drive of the gear. Thereby, a stroke is possible even if there is an already increased pressure in the pressure chamber with respect to the water pressure.

The invention can be realized particularly well with a drinking water heater with an air cushion for receiving expansion water comprising a venting fitting described above. In addition to such a venting fitting a drinking water heater also comprises a heatable, closed container for the heated water; an inlet for re-filling drinking water; and an outlet channel for hot water which ends at its inlet side below the water surface in the water and wherein the drinking water heater is provided with an air cushion above the water surface in the container for receiving expansion water. It is understood, however, that the invention may also be used with other applications where air shall be fed into a water flow.

A venting fitting described above can be operated with a method comprising the steps of:

(a) detecting the pressure drop within the water filled portion of the venting fitting with a pressure sensor when water is tapped from a downstream drinking water heater;

(b) transmitting the value detected in step (a) to a control device;

(c) comparing the pressure drop with a stored or calculated threshold value;

(d) determining the amount of air which must be introduced into the water filled portion of the venting fitting or a value representing the amount of air; and (e) introducing air by means of a drive until the amount of air or the value representing the amount of air reaches the value determined in step (d).

In particular, it can be provided that step (a) to step (c) is repeated once or more than once before air is introduced into the water filled portion of the venting fitting.

Contrary to known assemblies a control unit is used which controls the drive. This has the advantage that the air can be introduced at freely selectable points in time and with the desired duration, i.e. also in one go. The detection of the pressure renders the assembly independent from the tapping behavior of the user and together with the controlled drive essentially provides an ever same air cushion.

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

Definitions

In this description and in the accompanying claims all terms have the meaning well known to the person skilled in the art which is defined in technical literature, norms such as DIN EN 801-1 and DIN EN 1717 and the relevant internet sites and publications, in particular of the lexical kind, such as www.wikipedia.de,www.wissen.de or www.techniklexikon.net, of competitors, research institutes, universities and associations, such as, for example, Deutscher Verein des Gas- und Wasserfaches e.V. or Verein Deutscher Ingenieure. In particular, the terms used here have not the opposite meaning of what the person skilled in the art will derive from the above publications.

Furthermore, the following meanings are the basis for the used terms:

shutoff device	is any kind of device which will block a fluid flow either entirely or partially. Typical shutoff devices are ball valves or valves.
drive	unit converting energy in mechanic kinetic energy.
fitting	is a component for the installation in or at a pipe, conduit or tubing or any other fluid installation for blocking, controlling or influencing of mass flows. A fitting may be designed as one portion only ore with a plurality of portions and is installed at one point in or at the pipe, conduit or tubing. Fittings are, for example and not exclusively: connection devices, connection fittings, main service valves, service fittings, throttle fittings, taps, tap installations, drain fittings, safety fittings, backflow protection devices, adjusting fittings.
outlet	is an outlet side opening in a housing where a mass flow can flow out. In particular, the opening may be connected to a pipe or another fitting or freely open towards the atmosphere.
axial	is the direction of the rotational axis of components which are entirely or partially rotationally symmetric, such as pipes, tubes or elongated housings. In components without rotationally symmetry it designates the main flow direction in a section of the component.
bore hole	is any kind of connection between to cavities and blind holes.
pressure pressure reducer	force per area unit is a fitting for adjusting a selected pressure in downstream components.
passage inlet	is a connection enabling mass flows. is an upstream opening in a housing where a mass flow can flow into. In particular, the opening may be connected to a pipe or another fitting or open freely towards the atmosphere.
housing	limitation for matter, components, instruments and measuring devices towards the outside. A housing can be one portion or be constituted of a plurality of connected portions and may be constituted of one or more materials.

gear	is a machine element for converting kinetic properties. It has a drive where the transmitted force is entered and an output side connected to the tool or a machine.
piston	component forming together with a surrounding housing a cavity wherein the volume is changed by movement of such component.
motor	machine carrying out mechanical work by converting energy to kinetic energy
nut	machine element for providing releasable connections. The nut is a hollow body with an inner thread.
radial	direction perpendicular to an axial direction.
Pipe	hollow body comprised of cylindrical sections. It usually serves as a pipe line.

backflow preventer safety fitting to prevent backflow. A device which is designated to

shoulder	prevent the backflow of a fluid flow in a direction opposite to a designated flow direction. transition between section having different diameters or thicknesses.
socket	rim or transition portion at an opening.
turbine	rotating flow machine, for example an impeller, which converts the drop of inner energy of a flowing fluid to mechanical power which is transferred by its shaft.
valve	component for blocking or controlling a fluid flow.
tapping	taking water from an installation, at, for example, a water tap or by means of an apparatus

Brief description of the drawings

Fig.l	is a perspective representation of a drinking water heater with an upstream pressure reducer, venting fitting, and safety valve.
Fig.2	shows the fittings upstream of the drinking water heater of figure 1 in greater detail.

Fig.3 is a perspective view of a venting fitting for the installation in an assembly with a drinking water heater shown in figure 1.

Fig.4 is a top view of the assembly of figure 3.

Fig. 5 is a side view of the assembly of figure 3.

Fig. 6 is a perspective view of the assembly of figure 3 from a further perspective.

Fig.7 shows the gear used for the venting fitting of figure 3 from a side perspective.

Fig. 8 shows the gear used for the venting fitting of figure 3 from perspective from an inclined top perspective.

Fig. 9 is a vertical cross section of the venting fitting of figure 3 along a sectional plane A-A.

Fig. 10 is a horizontal cross section of the venting fitting of figure 3 along a sectional plane F-F with a piston at the dead center.

Fig. 11 is a horizontal cross section of the venting fitting of figure 3 along a sectional plane F-F with the piston between two dead centers.

Fig. 12 is a vertical cross section of the venting fitting of figure 3 along a sectional plane G-G.

Fig. 13 is a horizontal cross section of the venting fitting of figure 3 along a sectional plane D-D.

Fig. 14 is a partially cut, perspective view of the venting fitting of figure 3.

Fig. 15 is a detail of figure 10 illustrating how air is sucked through a backflow preventer into the housing socket.

Fig. 16 is a detail of figure 10 illustrating how compressed air in the housing socket flows into the water filled interior of the housing of the fitting passing a grooved ring.

Fig. 17 is a side view of a venting fitting with motor according to a second embodiment.

Fig. 18 is a vertical cross section of the assembly of figure 17.

Fig. 19 is a section of figure 18 and shows the motor in greater detail.

Fig.20 is an exploded view of the motor for a venting fitting according to figure 17.

Fig.21 is an enlarged detailed view of the piston and the inlet valve for a venting fitting according to figure 17.

Fig. 22 is a vertical cross section of the venting fitting of figure 17 along a sectional plane perpendicular to the pipe axis.

Fig.23 shows the course of the pressure drop without tapping procedure and with tapping procedure with filled and without air cushion in a drinking water heater.

Fig.24 shows the piston and air inlet- and air outlet valve in the lowest piston position.

Fig.25 is a cross section along a sectional axis C-C in figure 24 with the view from below.

Fig.26 shows the assembly of figure 24 in the upper end position of the piston.

Fig.27 shows the venting fitting of figure 17 in an installed state with a drinking water heater.

Description of the embodiments

Embodiment 1: hydraulic drive (Fig.l to Fig, 16)

Figure 1 shows a venting fitting generally designated with numeral 10. The venting fitting 10 is integrated in a pipe 12. A drinking water heater 14 is provided with water from such pipe 12. The water for the drinking water heater 14 is fed into the pipe 12 from a drinking water source (not shown) in the direction of the arrow 16. A shut-off valve 18 and a pressure reducer 20 are installed upstream before the venting fitting 10. This can be well recognized in figure 2. A safety group 22 with a safety valve and a backflow preventer are installed in the pipe 12 downstream of the venting fitting 10.

The drinking water heater 14 comprises a water-filled boiler 24. The boiler 24 not completely filled. An air cushion 28 is present above the water surface 26. Water is heated with the drinking water heater 14 by, for example, a heating coil. Hot water is provided a an outlet 31 extending into the water. If hot water is tapped at a tap (not shown) cold water is re-filled through the pipe 12.

Water expands upon heating. Thereby, pressure and temperature are increased. The air cushion allows for expansion without activating the safety valve. Air leaking from the air cushion during operation must be re-filled. The venting fitting 10 is provided for this purpose.

The venting fitting 10 is separately shown in figures 3 to 6. The venting fitting 10 is provided with a fitting housing 30. The fitting housing 30 is releasably closed with an upper lid 32 and a lower lid 34. The fitting housing 30 is provided with a tubular inlet connector 36 and a coaxial tubular outlet connector 38. The venting fitting is installed in the pipe 12 with the inlet connector 36 and the outlet connector 38 as it is shown in figure

2.

Furthermore, the fitting housing 30 is provided with two housing sockets 44 and 46. The housing sockets 44 and 46 are provided with tubular socket extensions 40 and 42, respectively. The socket extensions 40 and 42 are screwed into the sockets 44 and 46 with a thread 50 and sealed with a sealing 48. This can be well recognized in figures 9 to

11. The end of the socket extension 40 which is remote from the fitting housing 30 forms a first air inlet 52. The end of the socket extension 42 which is remote from the fitting housing 30 forms a second air inlet 54.

Figures 9 to 14 are cross sectional views of the venting fitting 10. Threaded pipe pieces 56 and 58 are screwed into the sockets 36 and 38. The threaded pipe pieces 56 and 58 are provided with a thread 60 at their free ends which can be screwed into the pipe. Water flows in the direction of arrows 62 into the fitting housing 30. The water flows in the direction of the arrows 64 out of the fitting housing 30 at the socket 38.

A wall 68 extends between the sockets 36 and 38 in the interior 66 of the housing. This can be well recognized in Figure 13. The wall 68 extends in a longitudinal direction through the interior 66 of the housing. Thereby two flow paths are generated: a first, larger flow path 70 extends through a backflow preventer 76 to the outlet socket 38. A second, smaller flow path 72 is further narrowed and tangentially flows to a turbine wheel 74.

The backflow preventer 76 opens towards the outlet socket 38 and forms a flow resistance. As long as only a small flow is generated, because, for example, only little water is tapped, only a small force is exerted on the backflow preventer 76 in the opening direction. The backflow preventer 76 will then remain closed. The entire flow flows through the second flow path 72. This causes a hydraulic drive on the turbine 74. With larger flow volumes the backflow preventer 76 will open and a flow is generated through both flow paths 70 and 72. The backflow preventer 76 causes the turbine wheel to be driven as much as possible even with small flows.

The turbine wheel 74 rotates in the direction of the arrow 78 when it is hydraulically driven by the flow in the flow path 72. The turbine wheel forms a portion of a gear which can be well recognized in the vertical cross sections in figure 9 and figure 12 and which is separately shown in figure 7 and 8.

The turbine wheel 74 rotates about a first shaft 80. The upper end of the shaft 80 is rotatably beared in a recess 82 in the lid 32. A gear wheel 84 having a smaller diameter is rotatably beared on the shaft 80 above the turbine wheel 74. The gear wheel has downwardly extending dogs 86 extending into the turbine wheel 74. Therefore, the gear wheel 84 will follow the rotational movement of the turbine wheel 74.

A larger gear wheel 88 cogs the smaller gear wheel 84. The larger gear wheel 88 is tightly connected to a downwardly extending shaft 90. The fitting housing 30 forms an essentially horizontal intermediate bottom 92. The intermediate bottom 92 is thickened in the range of the shaft 90 in a vertical direction, i.e. parallel to the shaft 90. A bore hole having a vertical longitudinal axis is provided in the thickened portion 94. The shaft 90 extends through the bore hole in the thickened portion 94 into the range below the intermediate bottom 92. This can be well seen in Figure 9.

A further, smaller gear wheel 96 is fixed to a shaft 90 below the intermediate bottom 92. The gear wheel 96 is torque proof connected to the shaft 90 and therefore, will follow a rotational movement of the shaft 90 and thereby of the gear wheel 88. A larger gear wheel 98 cogs the gear wheel 96. The gear wheel 98 rotates below the intermediate bottom 92 about the shaft 80, i.e. about the same rotational axis as the turbine wheel 74. The shaft 80 extends through a bore hole in the non-thickened range of the intermediate bottom 92. As can be seen in Figure 8 the gear wheel 98 has a larger diameter than the turbine wheel 74. Accordingly, the gear wheel 98 rotates slower than the turbine wheel 74.

A crank pin 100 is rotatably beared in an eccentric bore hole of the gear wheel 98. The crank pin 100 downwardly extends from the gear wheel 98 into the water filled interior 102 of the housing below the intermediate bottom 92. Two piston rods 104 and 106 diametrically opposite extend into the sockets 44 and 46. The free end of each piston rod is rotatably connected about a vertical axis to a lifting element in the form of a piston 108 and 110, respectively.

The socket extension 42 is provided with a longitudinal bore hole 112. The socket extension 40 is connected to a longitudinal bore hole 114. A piston 108 is movably guided in an axial direction in the longitudinal bore 112. A piston 110 is movably guided in an axial direction in the longitudinal bore 114. If the gear wheel 98 with the crank pin 100 rotates a translatoric movement of the pistons 108 and 110 is caused. The assembly with a common crank pin 100 for both pistons corresponds to the inverted power transmission of a V-180°-motor. This means that the pistons 108 and 110 will always move in the same direction - to the left or to the right in figure 9. In an alternative embodiment (not shown) two opposite crank pins are used. Only one piston is connected to each of the crank pins. The pistons will then move in opposite directions, i.e. both will move outwards or both will move inwards. This alternative embodiment corresponds to the inverted power transmission of a boxer motor.

The bore holes are slightly broadened at the free ends of the socket extensions 42 and 40 of the sockets 44 and 46 and form a shoulder. A backflow preventer 116 and 118 each is inserted into the bore holes 112 and 114, respectively, into the broadened bore hole up to the shoulder 124 forming a stop and fixed with a nut 120 and 122, respectively. This can be well seen in figure 15. The backflow preventers 116 and 118 are cartridge-like shaped and well known in the art. The backflow preventers 116 and 118 open inwardly in the direction of the arrows 126. This means that air from the atmosphere can be introduced into the bore holes 112 and 114, respectively, but cannot exit through the backflow preventer 116.

If the piston 108 moves towards the left as it is indicated in figure 15 the volume in the pressure chamber 134 is increased. Thereby, the air pressure drops. The backflow preventer 116 opens and air flows in the direction of the arrows 126 through the backflow preventer 116 into the pressure chamber 134. After reaching the dead center the piston moves back outwards, i.e. towards the right in figure 15. Then the volume in the pressure chamber 134 drops and the air pressure is increased.

A slit 140 is formed between the piston skirt and the inner wall of the bore hole 112. The slit 140 is connected to the water filled interior 102 of the housing 30 and, thereby, also filled with water. There is water pressure at the grooved ring on the side of the piston. Air pressure is present at the grooved ring on the side of the pressure chamber. If the air pressure in the pressure chamber 134 exceeds a threshold above the water pressure which is determined by the diameters, the material and the form of the grooved ring, the grooved ring 128 will be slightly pushed together in the range of the groove. Air from the pressure chamber 134 can pass the grooved ring 128 and the piston 108 and flow into the slit 140 and into the water filled interior 102 of the housing 30. This is well indicated by arrows 142 in figure 16. The piston 110 has the same design as the piston 108.

Larger bubbles are generated because the pressure difference between the water pressure and the air pressure in the pressure chamber 134 must be overcome. The bubbles rise in the interior 102 of the housing through a bore hole 144 into the range above the intermediate bottom 92 and into the flow path between the sockets 36 and 38. This is illustrated by arrows 146 and 148 in figure 12.

Figure 9 illustrates how the pistons 108 and 110 operated in opposite directions and thereby pump air into the interior 102 of the housing 30 and through the bore hole 144 in an alternating rhythm. The air enters the boiler 24 with the flow and can, thereby, fill the air cushion 28. The piston movement always occurs when a flow through the housing 30 is generated, i.e. when water is tapped at a tap.

The hydraulic force of the flow is continuously transferred to the pistons 108 and 110 by the turbine wheel. A longer flow duration will cause a longer piston movement through the use of the turbine and the introduction of more air.

Embodiment 2: motor drive (Fig, 17 to Fig,27)

Figure 17 shows an alternative venting fitting generally designated with numeral 210. The venting fitting 210 is integrated in a pipe 212. A drinking water heater 214 is provided with water from such pipe 12. The water for the drinking water heater 214 is fed into the pipe 212 from a drinking water source (not shown) in the direction of the arrow 262. This is shown in Figure 27.

The venting fitting 210 is provided with an inlet connector 236. This can be well recognized in figure 17 and figure 18. A shut-off valve 218 and a pressure reducer 220 are installed behind the inlet connector 236. This can be well recognized in figure 18. In the present embodiment the shut-off valve 218 and the pressure reducer 220 are integrated into the fitting. Thereby, the costs and efforts for installation are reduced. It is understood, however, that it is also possible to design the venting fitting 210 without a shut-off valve and/or without a pressure reducer 220. Such components may then be installed as separate components because they may be present already.

A safety group 222 with a safety valve and a backflow preventer 276 are integrated into the venting fitting 210 upstream of the outlet connector 238. As with the pressure reducer the safety group 222 may also be used in the form of a separate fitting and must not necessarily integrated into the venting fitting 210 as it is the case with the present embodiment.

The drinking water heater 214 corresponds to the drinking water heater 14 of the first embodiment. Also, the function of the venting fitting 210 corresponds to the function of the venting fitting 10 of the first embodiment.

The venting fitting 210 is provided with a fitting housing 230 which in the present embodiment consists of several portions. The fitting housing 230 is provided with a tubular inlet connector 236 and a coaxial tubular outlet connector 238. The venting fitting is installed in the pipe 212 with the inlet connector 236 and the outlet connector 38 as it is shown in figure 27.

Furthermore, the fitting housing 230 is provided a housing socket 244. The housing socket 244 extends in a downward direction. A further housing portion 246 is inserted into the housing socket 244 and fixed with a nut 250 and sealed with a sealing 248. This can be well recognized in figure 19.

The end of the second housing portion 246 which is remote from the fitting housing 230 has a tubular extending from the housing socket 244 and is open at its lower end. This can be well seen in the exploded view in figure 20.

Water flows in the direction of arrows 262 into the fitting housing 230. The water flows through the open shut-off valve 218 and the pressure reducer 220. A backflow preventer 276 is arranged in the flow path downstream of the pressure reducer 220 coaxially to the longitudinal axis of the tubular interior of the housing. The backflow preventer prevents that water flows back from the drinking water heater 214 into the installation. Downstream of the backflow preventer 276 the water flows in the direction of the arrows 264 out of the fitting housing 230 at the outlet socket 238.

The fitting housing 230 is provided with a further socket 22 f extending upwards in the representation. The interior of the socket 221 is connected to the range downstream of the backflow preventer 276 before the outlet socket. A safety group 222 is arranged in the socket 221. The safety group 222 will open upon overpressure in the drinking water heater 214 and water flows out until the pressure is sufficiently reduced.

The range inside the socket 244 which in this embodiment extends downwards is also connected to the water filled interior 266 of the housing of the fitting 230 between the backflow preventer 276 and the outlet socket 238. This can be well recognized in figure

19. Air is pushed into the water filled portion 266 inside the housing through such socket 244 as it is described below.

The end of the second housing portion 246 remote from the fitting housing 230 is tubular at the extension of the housing socket 244 and downwardly open. This can be well recognized in the exploded view in figure 20.

Water flows into the fitting housing 230 in the direction of the arrows 262. Then, the water flows through the open shut-off valve 218 and the pressure reducer 220. A backflow preventer 276 is arranged coaxially to the longitudinal axis of the tubular interior of the housing in the flow path downstream of the pressure reducer 220. The backflow preventer 276 prevents that water from the drinking water heater 214 flows back into the installation. At the outlet socket 238 downstream of the backflow preventer the water flows out of the fitting housing 230 in the direction of the arrow 264.

The fitting housing 230 is provided with a further socket 221 upwardly extending in the representation. The interior of the socket 221 is connected to the range downstream of the backflow preventer 276 before the outlet socket. A safety group 222 is provided in the socket 221. The safety group 222 opens upon overpressure in the drinking water heater 214 and water flows out until the pressure is sufficiently reduced.

The range inside the socket 244 downwardly extending in the present embodiment is also connected to the water filled interior 266 of the housing of the housing fitting 230 between the backflow preventer 266 and the outlet socket 238. This can be well recognized in figure 19. Air is pushed into the water filled portion 266 inside the housing through the socket 244 as described below.

The housing portion 246 is provided with a longitudinal bore hole 252. A piston 254 is moveably guided in an axial direction in the longitudinal bore hole 252. The piston 254 limits the underside of an air filled pressure chamber 256 in the housing portion 246. The pressure chamber 256 is upwardly limited by an air outlet valve 258. The air outlet valve 258 is designed like a backflow preventer and opens upwards in the representation in the direction of the water filled interior 266 of the housing. If the air pressure in the pressure chamber 256 is higher than the water pressure the air outlet valve 258 will open. Then air will flow from the pressure chamber 256 through the air outlet valve 258 into the water filled interior 266 of the housing 230.

The piston 254 is moveably guided in the longitudinal bore hole 252 coaxially to the moving direction of the valve closing body of the air outlet valve 258. An air inlet valve 260 sits in the piston. The open air inlet valve is shown in figure 21 in greater detail. The piston 254 is provided with a through bore 268 in a longitudinal direction for receiving the air inlet valve 260. A lower portion 270 and an upper portion 272 of the through bore 268 are connected by a guiding bore 274 and four connecting bores 276. Figure 25 is a cross section along the sectional line C-C in figure 24 where the position of the four connection bores 276 can be well seen.

The lower portion 272 of the through bore has a larger diameter than the guiding bore hole 274. Thereby, an annular shoulder 280 is formed at the inner wall of the through bore. The guiding bore hole 274 ends in an upper portion 272 of the through bore hole 268 which has a larger diameter than the guiding bore hole 274. Thereby, an annular shoulder 282 is formed at the inner wall of the through bore. The upper portion 272 is again wider at the uppermost end whereby a further annular shoulder 284 is formed at the inner wall of the through bore 268.

A spindle 286 is moveably guided in the guiding bore 274. The spindle 286 forms the lower portion of a valve closing body 288 for the air inlet valve 260. The valve closing body 288 is provided with an annular groove in the upper range accommodating a sealing 290. The annular shoulder 284 forms the valve seat of the air inlet valve 260. If the sealing 290 hits the shoulder 284 in a lower position of the valve closing body 288 the air inlet valve 260 is closed. This is shown in figure 19 and figure 26. The movement of the valve closing body 288 is downwardly limited by the annular shoulder 282 which forms a stop.

A spring abutment 292 is screwed on the lower end of the spindle 286. A spring 296 is provided between the spring abutment 292 and the annular shoulder 280. The spring 296 pushes the valve closing body 288 downwards into a closed position. If the piston 254 is moved downwards the volume in the pressure chamber is increased. Then the pressure in the pressure chamber 256 drops. The force of the reduced pressure in the pressure chamber 256 acting on the valve closing body 288 is smaller than the atmospheric pressure acting from below on the valve closing body 288 through the through bore 268 with the connection bores 276 which are open at the lower end towards the atmosphere. The valve closing body 288 will then be moved downwards. The air inlet valve 260 opens. Air from the atmosphere enters the pressure chamber 256 through the through bore 268, the connection bores 276 and passing the sealing 290 until the pressure conditions are level.

When the piston 254 is moved upwards the volume in the pressure chamber 256 is reduced again. Thereby, the pressure in the pressure chamber is increased. The air inlet valve 260 is closed. Due to the increased pressure the air outlet valve 258 opens as soon as the air pressure in the pressure chamber 256 is higher than the water pressure in the water filled interior 266 of the fitting housing 230. Air will be released into the water with open air outlet valve 258 until the pressure conditions are level again. This is shown in Figure 26. In such a way air from the atmosphere can be introduced into the pressure chamber 256 by a downwards movement of the piston and pressed from the pressure chamber 256 into the water filled interior 266 with an upwards movement. It is understood, that the terms up, down, downwards and upwards relate to the accompanying drawings and can be replaced by different positions and orientations with a different orientation of the valve.

The piston movement is achieved by means of a motor 300 as a drive instead of by hydraulics as in the first embodiment. Figure 20 is an exploded view of the components required for this purpose. A bearing with a cylindrical opening 302 is integrated in the tubular housing portion 246. The longitudinal axis of the opening 302 extends perpendicular to the longitudinal axis of the tubular housing portion 246. A bearing bushing 304 is inserted into the opening 302 of the bearing from the left in figure 20. This can be well recognized in figure 19.

The axis 308 of a rotating disc 306 is beared in the bearing bushing 304. The axis 308 is connected to the driving shaft 310 of the motor 300 and is driven by it. In the present embodiment a gear 312 is used between the motor 300 and the driving shaft 310.

A pin 312 is eccentrically formed onto the rotating disc 306 on the side remote to the bearing. When the driving shaft 310 and thereby the rotating disc 306 rotate about their own axis the pin 312 carries out a circular movement due to its eccentric position. A piston rod 314 is stuck onto the pin 312. The piston rod 314 of the present embodiment is a flat stick with rounded ends. A pin receiver 316 is provided at the lower end of the piston rod 314 rotatably accommodating the pin 312. The upper end of the piston rod extends between two downwardly extending extensions 318 of the piston 254. A fixing pin 320 is stuck through corresponding bores 322 in the extensions and in the piston rod 314 and fixed.

The rotational movement of the driving shaft 310 is transferred through the rotating disc 306 and the piston rod 314 to a translational movement of the piston 254. The piston 254 exercises a reciprocal movement pumping air into the pressure chamber 256 and from the pressure chamber into the water.

A control with a schematically indicated circuit board 324 is used for controlling the motor. The control receives the signals of a pressure sensor 326. The pressure sensor 326 sits in a socket 328 which is laterally integrated in the housing portion 246. The pressure sensor detects the pressure in the water filled interior 266 downstream of the air outlet valve 258.

The motor 300 and the components for transmitting the rotation of the driving shaft to the piston are commonly provided in the housing portion 246 and the pressure sensor 326 in a housing 330. Batteries or accumulators 332, which can be well recognized in figure 22, are provided as an energy source for the motor 300. The accumulators 332 are also provided inside the housing 330.

The motor 300 is controlled by the control 324 as follows: When water is tapped from the drinking water heater 214 at first the pressure in the entire water installation drops. The pressure drop depends on the tapped amount of water and from the volume velocity. Figure 23 shows the course 334 of the pressure drop delta P depending on the volume flow m³/h if no water is tapped. The course 336 of the pressure drop is rather flat with a normally filled air cushion in the drinking water heater. This is the case because the air cushion can better than water react to pressure changes and compensate them. If, however, the air cushion is only small or there is no air cushion anymore in the drinking water heater 214, then a steeper pressure drop 338 occurs with the volume velocity. The detection of the pressure drop can be particularly easily effected with a pressure sensor if there are always the same pressure conditions in the inlet range of the fitting. This can be ensured in a particularly advantageous way with a pressure reducer.

The pressure sensor detects the pressure conditions and the control 324 determines from the detected values if and to which extent the air cushion must be re-filled. The determination can be carried out several times in order to avoid erroneous measurements.

With the next idle phase of the system, such as at night, when no water is tapped, the motor can be started and air is pumped in. In such a way only the air cushion is filled, but no air is transported to the tap point or into the pipe system.

In order to reduce the energy consumption it can be provided that the pressure sensor transfers to an idle state after one or several measurements or after a given time interval where little or no electric energy is used. Flow detecting means can be provided. An example for such flow detecting means can be formed by a magnet 227 at the valve closing body of the backflow preventer 276. The magnet 277 cooperates with a Reed contact 279 in the housing near the valve seat or in or at the valve seat of the backflow preventer 276. When the backflow preventer opens during a tapping procedure, the valve closing body with the magnet 277 moves away from the Reed contact 279. It then detects a signal and sends it to the control 324. The control then switches the pressure sensor to an active state where the pressure is measured. The pressure sensor is active and uses energy only if there is a change of the hydraulic system.

The fitting may also be used without a pressure reducer and without a safety valve.

The embodiments described above serve to illustrate the invention claimed in the claims. Features which are disclosed together with further features may normally be also used alone or in combination with other features which are explicitly or implicitly disclosed in the text or in the drawings with respect to the embodiments. Sizes and diameters are indicated by way of example only. The person skilled in the art will derive suitable ranges from his/her own specific knowledge and must, therefore, not be discussed here in greater detail. The disclosure of a precise embodiment of a feature does not mean that the invention shall be limited to such a precise embodiment. Moreover the feature may be realized by many others which are well known to the person skilled in the art. The invention may, therefore, not be only realized in the form of the described embodiments but by all embodiments which are covered by the protective scope of the accompanying claims. In particular, further drives or more or less pistons or other lifting elements may be provided. Also, backflow preventers may be replaced by suitable flow resistances. Sockets may be integrated or have several portions, such as having socket extensions. There may be coaxial arrangements for the sockets or others.

The terms up, down, left and right only relate to the accompanying drawings. It is understood, that the claimed devices may also assume a different orientation. The term comprising and the term including mean that further not-mentioned components may 5 be provided. The term essentially, mainly or mostly means all features which have a property or a content more than others, i.e. more than all other components or features of the kind, i.e. with two components more than 50%.

Claims (16)

1. Venting fitting (10; 210) for drinking water heaters (14; 214) with an air cushion (28) for receiving expansion water, comprising:

(a) a fitting housing (30; 230) with a water inlet (36; 236) and a water outlet (38; 238) and a water filled housing interior (102; 266) arranged between the water inlet and the water outlet, (b) at least one air inlet (40, 42) provided at the fitting housing (30; 230) and adapted to be connected to atmosphere, (c) an inlet valve (116, 118) arranged in the air inlet, limiting an air filled pressure chamber (134), the pressure thereof acting in a closing direction on the inlet valve (116, 118), (d) a moveable lifting element (108, 110) limiting the pressure chamber (134), the movement thereof causing a volume- and pressure change in the pressure chamber (134) whereby the inlet valve (116, 118) is opened or closed; and (e) a direction dependent outlet valve (128) opening upon reaching a set pressure in the air filled pressure chamber (134), characterized in that (f) a drive is provided for moving the lifting element;

(g) the outlet valve (128) is provided between the air inlet and the water filled interior of the housing (102), whereby air will evaporate into the water filled interior of the housing (102) of the fitting housing (30) if the outlet valve (128) opens; and (h) the water inlet (36) and the water outlet (38) are adapted to be installed in the feeding pipe (12) of a drinking water heater (14).

2. Venting fitting according to claim 1, characterized in that the drive comprises a motor.

3. Venting fitting according to claim 2, characterized in that the motor is an electric motor which is feed with energy from an energy source with electric energy.

4. Venting fitting according to claim 3, characterized in that the energy source is formed by exchangeable batteries or accumulators.

5. Venting fitting according to any of the preceding claims, characterized in that (a) a pressure sensor is provided detecting the pressure, the pressure development and/or the pressure drop in the water filled portion of the fitting upon tapping of water; and (b) a control is provided which is fed by the signals of the pressure sensor, the control controlling the drive depending on such signals.

6. Venting fitting according to any of the preceding claims, characterized in that an inlet side pressure reducer is provided upstream of the inlet valve.

7. Venting fitting according to any of the preceding claims, characterized in that the inlet valve is a backflow preventer (116, 118).

8. Venting fitting according to any of the preceding claims, characterized in that the air inlet is provided at a tube-shaped housing socket (40, 42) and the lifting element comprises a piston (108, 110) which is moveably guided in the longitudinal direction in the housing socket (40, 42).

9. Venting fitting according to claim 8, characterized in that the inlet valve is provided interior the piston.

10. Venting fitting according to any of the preceding claims, characterized by a piston rod (104, 106) or another element for transmitting a rotational movement of the drive to the lifting element (108, 110).

11. Venting fitting according to any of the preceding claims, characterized in that the drive (74) drives a shaft (80) exerting a torque on a rotatable element (98) having the end of the piston rod remote from the lifting element eccentrically and rotatable connected thereto.

12. Venting fitting according to any of the preceding claims, characterized in that a safety valve is provided in the outlet downstream of the inlet valve.

13. Venting fitting according to any of the preceding claims, characterized in that a ball valve or any other shut-off valve is provided in the inlet.

14. Drinking water heater (14) with an air cushion (28) for receiving expansion water comprising a venting fitting (10) according to any of the preceding claims.

15. Method for operating a venting fitting according to any of the claims 1 to 13 with the steps of:

(a) detecting the pressure drop within the water filled portion of the venting fitting with a pressure sensor when water is tapped from a downstream drinking water heater;

(b) transmitting the value detected in step (a) to a control device;

(c) comparing the pressure drop with a stored or calculated threshold value;

(d) determining the amount of air which must be introduced into the water filled portion of the venting fitting or a value representing the amount of air; and (e) introducing air by means of a drive until the amount of air or the value representing the amount of air reaches the value determined in step (d).

16. Method according to claim 15, characterized in that step (a) to step (c) is repeated once or more than once before air is introduced into the water filled portion of the venting fitting.