A PUMP

The present invention relates to pumps, and particularly, although not exclusively to domestic water pumps. In particular, the invention relates to domestic shower pumps, and to methods of boosting the power of a domestic shower apparatus.

There are a number of shower types available on the market, one example of which is the gravity fed shower system as shown in Figure 1. Mains water source is supplied from a mains water source through conduit 2 to fill a cold water storage tank 4, which is often located in the attic. Cold water is fed under gravity through conduit 6 into a hot water storage tank 8, where the cold water is heated. Cold water is fed under gravity from the cold water storage tank 4 through conduit 10 to a cold mixer tap 14, and hot water is fed from the hot water storage tank 8 through conduit 12 under gravity to a hot mixer tap 16. A user adjusts cold and hot water taps 14, 16, respectively, in order to mix the water to the required temperature, and then deliver the mixed water under gravity through conduit 18, and out of a shower head 20. The greater the vertical distance between the shower head 20 and the water level in the cold water storage tank, the greater the flow out of the shower head 20.

However, a problem encountered with the shower system shown in Figure 1 is that the pressure and, hence, flow available at the shower head 20 is often too low for a user to have a satisfactory shower. The usual method of solving this problem is to install an electric booster pump in the hot conduit 12 and/or cold conduit 10 or a power shower unit that mixes and boosts the water from the hot and cold lines 12,10. However, electrical shower booster pumps are very inefficient and typically convert only about 1 %-6% of the electrical energy into the flow/pressure energy of the shower water supplied to the shower head.

The power contained in the flow of water to a shower may be calculated from the following formula I (Cengal, Y.A., Turner, R. H., 2001 , Fundamentals of Thermal-Fluid Sciences, Boston: Mcgraw-Hill, p142)

WorkFlow{J) = Pr essure(Pa) x Volume(m ³ )

[Formula I]

For a good quality shower of approximately 8 litres/min at a pressure of 0.5 bar, this amounts to a power requirement of approximately 6.5 Watts. In order to supply this power, an electric booster pump typically consumes 100-330 Watts. Hence, the pump is very inefficient. A further problem with booster pumps and power showers is the expense of the electrical components in each system, and the requirement of an electrical supply to be installed to power the booster pump or power shower unit, and also its running costs. In addition, installation of electrical booster pumps and power shower units legally requires technical expertise.

Hence, there is a pressing need for an alternative system for increasing the pressure in a hot and/or cold shower water supply without the problems mentioned above. One method, which attempts to achieve this, is described in GB 2,191 ,245, which discloses feeding the mains cold water supply directly into the hot water supply so that they mix together, in order to increase the flow and pressure of the mixed water for showering. However, a significant disadvantage of this arrangement is that it is difficult to accurately control the temperature of the shower water being used for the shower because the cold mains water and hot shower water are mixed together. For example, if the hot water is already at optimum showering temperature before it has even been mixed with the mains water, then once it is mixed with the cold mains water in order to increase its pressure, the temperature is decreased to significantly below optimum showering temperature. Hence, the user is presented with a dilemma of having to choose between having a shower in which the shower water is:- (i) at the correct pressure and flow, but is uncomfortably cold (due to the mixed cold mains water supply being introduced); or (ii) at the correct temperature, but at insufficient pressure and flow for an enjoyable shower.

It is therefore an object of the present invention to obviate or mitigate one or more of the problems of the prior art, whether identified herein or elsewhere, and to provide a pump exhibiting improved water flow and pressure

characteristics, and which may be used for boosting the pressure of shower water at comfortable showering temperatures.

The inventor set out to try and solve the problems inherent with the prior art shower systems and shower pumps, and investigated numerous pump designs to see which was the most efficient. In looking for a pump to meet the various requirements, the inventor found that existing electric pump designs and power showers have low efficiency for boosting the pressure of the shower water, due to using a centrifugal pump head running at relatively low flow rates. Furthermore, for all of the known pumps tested, a large percentage of energy is lost during the conversion of energy from the electric motor to the pump head to the shower water pressure, and hence, an inefficient boosting effect was observed. Accordingly, the inventor had to use significant inventive endeavour to design a novel pump for use in boosting shower water. The new shower pump, and shower system incorporating the pump, is able to efficiently boost or increase the pressure and flow rate of the shower water, thereby increasing the enjoyment for a user of a shower in which the shower pump is integrated without suffering the problems experienced with the prior art. The inventor believes that uses of the new pump he has invented are not limited solely to boosting shower water, but could be used for pumping any fluid using the pressure of another fluid.

Hence, according to a first aspect of the present invention, there is provided a pump for pumping fluid, the pump comprising a first chamber for receiving a first fluid, and a second chamber for receiving a second fluid, the pressure of the first fluid being higher than the pressure of the second fluid, and the pump comprising pumping means operable, in use, to pump the second fluid out of the second chamber using the pressure of the first fluid in the first chamber, characterised in that the first and second chambers are not in fluid communication with each other such that the first and second fluids do mix inside the pump.

The inventor believes that the pump according to the invention is unique due to the features that the first and second chambers are not in fluid communication with each other thereby preventing mixing of the fluids inside

the pump, and that the fluid in the first chamber is used to indirectly boost the pressure of fluid in the second chamber and therefore the flow rate of the second fluid therefrom.

By the term "indirectly boost", we mean the pressure of the second fluid is increased by harnessing the higher pressure of the first fluid in the pump without any direct contacting between the two fluids in the pump. Hence, the two fluids do not mix with each other within the pump. This is advantageous in many instances where the mixing of the first and second fluids is undesirable, for example, for boosting the pressure of shower water.

The first and second fluids may be the same or different. The first and second fluids may be independently gaseous or liquid. For example, both fluids may be gaseous, or one fluid may be gaseous and the other may be liquid. However, preferably both the first and second fluids are liquid, and preferably water.

Preferred embodiments of the pump are illustrated in the various Figures, and are described in the Example. Preferably, the pump comprises an inlet and an outlet for the first fluid. For example, in use, the inlet for the first fluid is preferably adapted to be in operable communication with a mains water supply. Preferably, in use, the outlet is adapted to be in operable communication with a cold water storage tank. Hence, mains water leaving the pump is preferably fed to the cold water storage tank.

Preferably, the pump comprises an inlet and outlet for the second fluid. Preferably, in use, the inlet for the second fluid is adapted to be in operable communication with a cold water supply, and preferably, a hot water supply, and more preferably hot/cold mixed water supply. Accordingly, the inlet for the second fluid is preferably adapted to receive cold water, hot water and/or hot/cold mixed water. The outlet of the second fluid may be connected to any domestic water apparatus, for example, a tap, bath, sink, or shower.

In one embodiment, the pumping means may comprise a turbine in fluid communication with the first chamber, and a centrifugal pumping means in fluid communication with the second chamber. Preferably, in use, the turbine is driven by the pressure of the first fluid, which causes the centrifugal pumping means to pump the second fluid out of the second chamber. Preferably, the centrifugal pumping means is operably attached to the turbine by a shaft and bearing assembly.

In another embodiment, the pumping means may comprise a diaphragm in operable communication with, but forming a physical barrier between, the first and second fluid chambers, wherein as the first fluid flows into the first chamber, it urges the diaphragm to urge the second fluid out of the second chamber. The diaphragm is preferably mounted within a housing, wherein, in use, the pressure of the first fluid causes the diaphragm to oscillate to thereby pump the second fluid out of the second chamber as first fluid flows into the first chamber. The diaphragm and housing may together comprise a concertina arrangement.

In a preferred embodiment, the pumping means comprises a piston in operable communication with, but forming a physical barrier between, the first and second chambers, wherein in use, as the first fluid flows into the first chamber, the piston is urged to pump the second fluid out of the second chamber. Hence, advantageously, the piston pumps the second fluid out of the second chamber by using the pressure of the first fluid within the first chamber without any mixing between the first and second fluids in the pump. Preferably, the piston is moveably mounted within a housing. The housing and piston arrangement may form a cylinder.

Preferably, the piston comprises at least one piston head, the second chamber being defined by one side of the at least one piston head and the housing, and the first chamber being defined by the opposite side of the at least one piston head and the housing. Hence, the piston head acts as a

physical barrier between the respective first and second chambers to prevent the fluids from mixing in the pump.

It is preferred that the piston comprises a double-ended piston comprising first and second piston heads, which heads are both moveably mounted within the housing. Therefore, it is preferred that the pump comprises two chambers for receiving the second fluid, each second fluid receiving chamber being defined by one side of each piston head and the housing. Preferably, the pump comprises two chambers for receiving the first fluid, each first fluid receiving chamber being defined by a side of each piston head and the housing which is opposite to that of the second fluid receiving chamber. It is most preferred that the two chambers for receiving the second fluid are defined by an outer side of each piston head and the housing, and the two chambers for receiving the first fluid are defined by an inner side of each piston head and the housing. However, it should be appreciated that it is possible to have the reverse arrangement in which the two chambers for receiving the second fluid are defined by an inner side of each piston head and the housing, and the two chambers for receiving the first fluid are defined by outer side of each piston head and the housing. By the terms "inner and outer side of the piston head", we mean with respect to the central region of the pump, as illustrated in the Figures.

Preferably, the first piston head is moveable between a first position in which it creates a second chamber for receiving the second fluid, and a second position in which that second fluid chamber is substantially reduced in volume. It will be appreciated that when the first piston head is in the second position, it creates a first chamber for receiving the first fluid, and when the first piston head it is in the first position, that first fluid receiving chamber is substantially reduced in volume. Preferably, the second piston head is moveable between a first position in which it creates a second chamber for receiving the second fluid, and a second position in which that second fluid receiving chamber is substantially reduced in volume. It will be appreciated that when the second piston head is in the second position, it also creates a first chamber for

receiving the first fluid, and when the second piston head is in the first position, that first fluid chamber is substantially reduced in volume.

Preferably, the first piston head is operably attached to the second piston head by connection means so that when the first piston head is in the first position, the second piston head is in the second position, and when the first piston head is in the second position, the second piston head is in the first position. The connection means may be a connecting rod or arm or the like.

Preferably, the pump comprises a valve operable in use to feed the first fluid to the or each piston head, wherein pressure applied by the first fluid on the or each piston head urges the or each piston head to move between the first and second positions. This causes the volume of the corresponding first and second fluid receiving chambers to be varied, so that pumping occurs without any mixing between the first and second fluids. The valve preferably comprises a conduit comprising first and second outlets through which the first fluid may flow towards the or each piston head. Preferably, the valve comprises a first internal piston slideably mounted within a chamber, the first internal piston being in operable communication with the conduit, and moveable between a first position in which the first outlet is open, wherein the first fluid flows to the first piston head, and a second position in which the second outlet is open, wherein the first fluid flows to the second piston head. Preferably, the first internal piston comprises at least two channels extending therethrough, which channels are arranged to align with either the first or second outlet depending on the position of the internal piston to allow the first fluid to flow therethrough.

Hence, preferably, the double-headed piston is adapted to oscillate between a first position in which the first piston head is in its first position thereby defining the second fluid receiving chamber and the second piston head is in its second position thereby expelling the second fluid from its corresponding chamber, and a second position in which the second piston head is in its first position, and the first piston is in its second position. Hence, it should be appreciated that the oscillating action of the double-headed piston in the pump causes the second fluid to be pumped out of each chamber, and

eventually out of the second fluid outlet. Preferably, the pump comprises a conduit in operable communication with the first fluid outlet along which the first fluid may be removed from the pump once it has been used to pump the second fluid out of the second chamber of the pump. It is preferred that when the pump is in use, the conduit is operably attached to a cold water supply tank.

The inventor has found that the maximum efficiency for the pump according to the invention is achieved by having a minimum number of flow reversals (i.e. pumping actions between the first and second positions of each piston head) and, hence a high cylinder volume. In addition, the inventor believes that the larger the diameter of the cylinder formed by the piston or diaphragm in the housing, the higher the efficiency, due to the ratio of wall friction force to total driving force being smaller than would be the case for a narrower diameter piston/diaphragm and cylinder. Thus, a preferred pump according to the invention comprises a large pumping volume achieved from a shorter, large diameter piston and cylinder (rather than a long, thin one). Accordingly, preferably the ratio of the diameter of the piston to the length of the piston (ie cylinder) is at least 1 :1 , more preferably at least 2:1 , even more preferably at least 3:1 , and most preferably, at least 4:1.

Therefore, large volumes are pumped in a single stroke (from first to second position), and fewer strokes will take place in a given time, thereby reducing frictional losses.

Preferably, the pump comprises oscillation means for oscillating the piston and, hence the or each piston head, between its respective first and second positions. Advantageously, continual oscillation of the piston prevents the equalisation of pressure within the pump, which would otherwise cause the pump to stop pumping, and hence, ensures continuous pumping until the pump is de-activated by a user.

As shown in Figure 5, in one embodiment, the oscillation means may comprise a plurality of conduits or channels within the valve, along which the first fluid may flow in order to urge the or each piston head between the first

and second positions. Hence, preferably, the valve comprises two further conduits, each comprising first and second outlets through which the first fluid may flow towards channels at either end of the first internal piston. Preferably, the two further conduits are in fluid communication with the first fluid inlet of the pump. Accordingly, preferably, the first fluid is always able to flow into one or the other further conduit irrespective of the position of the first internal piston.

Preferably, the valve comprises a second internal piston that is slideably mounted within a chamber between first and second positions, which piston is in operable communication with the two further conduits and is adapted in use to direct flow of the first fluid within the valve towards either end of the first internal piston depending on the position of the second internal piston. Preferably, the second internal piston comprises at least two channels extending therethrough, which channels are arranged to align with either of the two further conduits, depending on the position of the second internal piston in the valve to allow the first fluid to flow therethrough to one end of the first internal piston.

Preferably, when the second internal piston is in either its first or second position, one end of the piston protrudes beyond a plane of the valve and into the first fluid receiving chamber. Preferably, in use, the protruding end of the second internal piston is engageable by a piston head as it moves from the second position to the first position, to thereby cause the second internal piston to be urged in to its opposite position thereby causing a change in first fluid flow within the valve so that it flows along the other further conduit. Hence, the first fluid is fed into the valve along one of the two further conduits, through one of the channels in the second internal piston, and then behind one side of the first internal piston causing it to shift position, which thereby causes the piston (and one of its piston heads) to shift from its second to the first position. As the piston head moves to its first position, it abuts the protruding end of the second internal piston, so that its position shifts, thereby aligning its other channel with the other of the two further conduits, and this in turn causes the first fluid to flow along the other of the two further conduits,

and then behind the other side of the first internal piston, causing it to shift position. Insodoing, the first and second internal pistons oscillate thereby causing the double headed piston to oscillate, such that the second fluid is continually drawn into and pumped out of corresponding second fluid receiving chambers. In addition, the first fluid is continually fed to the cold water storage tank.

As shown in Figure 14, in another embodiment of the pump, the oscillation means for oscillating the or each piston head comprises a second and third internal pistons, which are adapted in use to individually urge the first internal piston between its corresponding first and second positions, such that the first fluid is fed towards the or each piston head. Preferably, the second internal piston is in operable communication with the first internal piston and the first piston head, and the third internal piston is in operable communication with the first internal piston and the second piston head.

Preferably, the means for oscillating the or each piston head comprises biasing means operable to urge the second and third internal pistons away from the first internal piston, such that a portion thereof protrudes beyond a plane of the valve and into the first fluid receiving chamber. Preferably, a first biasing means is disposed between the first and second internal pistons, and a second biasing means is disposed between the first and third internal pistons. Preferably, the second and third internal pistons are disposed inside an arm of the piston, which connects the first and second/third piston heads together. The biasing means may comprise a spring, and preferably a helical spring.

The pump preferably comprises retaining means for at least temporarily retaining the first internal piston, and hence the first and second piston heads, either in the first or second position. Preferably, the retaining means comprises engagement means operable to engage receiving means provided in the first internal piston. The receiving means may comprise first and second slots or notches suitably sized to receive the engagement means, and hence, retain the first internal piston in either the first or second position. The first and second slots are preferably spaced apart. Preferably, in use, when the

engagement means engages the first slot, the first internal piston is arranged such that the first piston head is in its first position and the second piston head is in the second position, and when the engagement means engages the second slot, the first internal piston is arranged such that the first piston head is in its second position and the second piston head is in the first position.

The engagement means is preferably biased by biasing means into the receiving means (ie the first or second slot) as the first internal piston oscillates. The biasing means may comprise a spring. The engagement means may comprise a ball-bearing. Accordingly, preferably the receiving means and preferably the first and second slots thereof, are suitably sized to receive the engagement means.

In use, the first fluid is fed into the pump through the first fluid inlet, and then into the valve. The first fluid flows through the conduit, and behind one of the piston heads, thereby urging the piston head from the first position to the second position, and insodoing, causing the other piston head to move from the second position to the first position. The channels extending through the first internal piston is moved in and out of alignment with the conduit to thereby urge the first fluid behind the other piston head. The means for oscillating the or each piston head ensures continuous pumping. It will be appreciated that the first fluid and second fluid do not mix at all in the pump.

Preferably, the pump comprises a first conduit for the second fluid, which first conduit is in operable communication with the second fluid inlet and the or each second fluid receiving chamber. Preferably, said first conduit for the second fluid comprises a one-way valve operable to prevent the second fluid exiting the pump via the second fluid conduit. Preferably, the pump comprises a second conduit for the second fluid, which second conduit is in operable communication with the second fluid outlet and the or each second fluid receiving chamber. Preferably, said second conduit for the second fluid comprises a one-way valve operable to prevent the second fluid in the second fluid outlet from feeding back to the second fluid receiving chamber.

Preferably, the pump comprises a first conduit for the first fluid, which first conduit is in operable communication with the first fluid inlet and the or each first fluid receiving chamber. Preferably, said first conduit for the first fluid is in operable communication with the valve. Preferably, the pump comprises a second conduit for the first fluid the conduit being in operable communication with the first fluid outlet and the or each first fluid receiving chamber.

Preferably, the pump comprises flow rate control means capable of providing a substantially constant flow rate of the second fluid exiting the pump when in use. Preferably, the control means is in operable communication with the second fluid outlet. Preferably, the second fluid flow rate control means comprises a chamber for receiving the second fluid and a third fluid, and is adapted to compress the third fluid contained in the chamber as second fluid flows therein. It will be appreciated that as the or each piston oscillates between the first and second positions, the flow of second fluid from the second fluid outlet momentarily drops. Hence, it is preferred that the flow rate control means is operable to urge the second fluid present in the chamber outwardly therefrom due to the compressed third fluid therein, thereby ensuring a constant pressure and flow of the second fluid out of the chamber and eventually out of the second fluid outlet. The third fluid is preferably a gas, such as, air. For example, the flow rate control means may comprise an impulse dampener, which will be known to the skilled technician (Fawcett Christie Hydraulics Ltd, Glendale Avenue, Sandycroft Industrial Estate, Sandycroft, Deeside, Flintshire, CH5 2QP)

Preferably, the pump comprises an automatic shut-off valve capable of automatically preventing flow of the first fluid into the pump when the pump is switched off. Advantageously, this prevents the pump from leaking due to pressure caused by the first fluid in the pump. Preferably, the shut-off valve is in operable communication with the first fluid inlet of the pump, and defines a passageway having a valve seat disposed therein. It is preferred that the valve seat comprises a tapered portion of the passageway, thereby defining a narrowed section therein. Preferably, the shut-off valve is in operable communication with the second fluid outlet of the pump. Preferably, the shut-

off valve comprises closure means disposed between the first fluid inlet and the second fluid outlet, which closure means is movable between a valve- closed position, in which the closure means sealingly engages the valve seat, and a valve-open position in which the closure means is spaced from the valve seat. Preferably, the closure means is substantially resilient, for example, a flexible diaphragm. Figures 24 and 25 illustrate the valve in open and closed configurations, respectively.

The inventor believes that the pump according to the first aspect of the invention has many uses for pumping fluids. For example, the pump may be used to pump a domestic water supply for use in the house or garden, for example, into a sink, bath, or shower, or out of a hose pipe, sprinkler, or water fountain or the like. Hence, preferably, the first fluid received by the first chamber of the pump is mains water.

By the term "mains water", we refer to water that is fed to a domestic household, and which is not used directly (eg for washing up, showering or bathing, or for use in the garden). Mains water is fed from the mains supply to a cold water storage tank where it is at least temporarily stored before being fed to the pump according to the invention and used. Hence, mains water as defined herein is any water upstream of the cold water storage tank.

Cold water in the cold water storage tank may be heated, for example, for use in a bath or shower or for washing up, and is stored in a hot water storage tank. Accordingly, preferably, the second fluid is fed from a cold water storage tank and/or a hot water storage tank to the pump according to the invention. Preferably, the second fluid is domestic water for any domestic use, for example, sink water, bath water, or shower water, or water for use in the garden, such as hose pipe water, sprinkler or irrigation water, or water fountain water. Hence, in preferred embodiments, the pump according to the first aspect is a domestic water pump. It is therefore preferred that the pump comprises a domestic water pump comprising a first chamber for receiving mains water, and a second chamber for receiving a domestic water supply, the pressure of the mains water being higher than the pressure of the domestic water supply, and the pump comprising pumping means operable, in

use, to pump the domestic water out of the second chamber using the pressure of the mains water in the first chamber, characterised in that the first and second chambers are not in fluid communication with other such that the mains water and the domestic water do mix inside the pump.

However, most preferably, the second fluid is shower water.

By the term "shower water", we refer to water that is used directly for showering by someone using a domestic shower. Shower water is fed from the cold water storage tank and/or the hot water storage tank to the pump according to the invention, and from the pump to a tap, and then to a shower head. Hence, shower water as defined herein as any water downstream of the hot and/or cold water storage tanks.

Hence, in preferred embodiments, the pump according to the first aspect is a shower pump. It is therefore preferred that the pump comprises a shower pump comprising a first chamber for receiving mains water, and a second chamber for receiving shower water, the pressure of the mains water being higher than the pressure of the shower water, and the pump comprising pumping means operable, in use, to pump the shower water out of the second chamber using the pressure of the mains water in the first chamber, characterised in that the first and second chambers are not in fluid communication with other such that the mains water and shower water do mix inside the pump.

The inventor has realised that the pressure of the shower water when un- boosted is dependent on the vertical distance between the shower head and the water level in the cold water storage tank. In addition, the amount of energy available from the mains water for boosting the shower water by the pump varies with location and position, and may be calculated from Formula I. For example, the power available for driving the pump according to the invention may be about 39 Watts for a domestic mains water supply at an average pressure of about 3bar provided at a flow rate of 8 litres/min. Surprisingly, the inventor believes that 39W of power from the mains water supply is sufficient for the pump according to the invention for boosting the

pressure of shower water to produce a good shower. Furthermore, despite the relatively low energy that is available in the mains water pressure to drive the pump, the inventor has surprisingly found that pump efficiencies in excess of 60% can be achieved, thus making for a satisfactory shower even in circumstances when the mains water pressure may be low. Such power efficiencies are not achievable with prior art pumps.

Hence, advantageously, the pump according to the invention is capable of harnessing the high pressure of the mains water to indirectly increase or boost the pressure of the shower water, without mixing the mains water and shower water before the shower water exits the pump. The result is that the power and flow rate of the shower water can be boosted without experiencing any disadvantageous temperature decrease in the shower water as experienced with known shower pumps. Hence, the pump ensures the water temperature out of the shower head is less sensitive to water supply pressure fluctuations, as these affect both hot and cold flows equally. Another advantage of the pump according to the inventor is that it is very efficient, and, due to the nature of its design, it is almost silent when in use. This is a significant advantage over existing shower pumps which have a tendency to be very noisy due to their use of electric motors, which has a detrimental effect on the enjoyment of the shower. The pump is also suitable for negative head environments due to the nature of its design, as will be described hereinafter.

Preferably, the pump comprises an inlet and outlet for the mains water. Preferably, in use, the inlet for the mains water is adapted to be in operable communication with a mains water supply. Preferably, in use, the outlet for the mains water is adapted to be in operable communication with a cold water storage tank. Hence, mains water leaving the pump is preferably fed to the cold water storage tank.

Preferably, the pump comprises an inlet and outlet for the shower water. Preferably, in use, the inlet for the show water is adapted to be in operable communication with a cold water supply, and preferably, a hot water supply, and more preferably hot/cold mixed water supply. Accordingly, the inlet for the

shower water is preferably adapted to receive cold water, hot water and/or hot/cold mixed water.

Based on his findings, the inventor believes that the pump according to the first aspect of the invention may be used for boosting the pressure and hence, flow rate of a fluid.

Hence, according to a second aspect of the present invention, there is provided use of a pump according to the first aspect for indirectly boosting the pressure of one fluid using pressure of another fluid, wherein the fluids do not mix.

Furthermore, in a third aspect, there is provided a method for indirectly boosting the pressure of one fluid using pressure of another fluid, the method comprising feeding a first fluid into a first chamber of a pump, feeding a second fluid into a second chamber of a pump, the pressure of the first fluid being higher than the pressure of the second fluid, and pumping the second fluid out of the second chamber using the pressure of the first fluid in the first chamber, characterised in that the first and second chambers are not in fluid communication with other such that the fluids are not mixed inside the pump.

Following boosting of the pressure of the second fluid, preferably the use of the second aspect and the method of the third aspect comprise feeding the first and second fluids away from the shower pump, for example, to a reservoir. Preferably, the method comprises feeding the first fluid used to pump the second fluid to the reservoir at a rate which is substantially the same as the outlet flow of second fluid from the reservoir to the pump. The reservoir may be a cold water storage tank. This is advantageous as it keeps the level of water in the cold water storage tank substantially constant when the pump is in use.

The inventor believes that to date, domestic water systems do not exist which are able to indirectly boost the useable water with the pressure from the mains water supply.

Hence, according to a fourth aspect, there is provided a domestic water system comprising a pump according to the first aspect in operable communication with a mains water supply.

Preferably, the system comprises a cold water storage tank which receives mains water. Preferably, the system comprises a conduit feeding domestic useable water from the cold water storage tank to the pump. The system may comprise a conduit feeding cold water to a hot water storage tank, in which the cold water is heated to produce hot water. The domestic water system may comprise two pumps according to the first aspect of the invention. For example, the system may comprise a first pump according to the first aspect in operable communication with the cold water tank, and a second pump according to the first aspect in operable communication with a hot water tank. Alternatively, the water system may comprise one pump according to the first aspect, to which is fed both hot and cold water supplies.

Preferably, the water system comprises a conduit extending between the pump and the cold water storage tank along which mains water that has been used to boost the pressure of the water is may be fed. Preferably, said feeding is carried out at a rate which is substantially similar to the outlet flow of the water from the hot or cold water storage tank to the pump. Preferably, the domestic water system according to the fourth aspect is a domestic shower system.

The inventor also believes that he has devised a new method for installing domestic water systems.

Hence, according to a fifth aspect, there is provided a method of installing a domestic water system, the method comprising connecting a pump according to the first aspect of the invention to a mains water supply.

Preferably, the method of the fifth aspect produces the domestic water system of the fourth aspect.

In summary, the invention provides a pump, which uses the energy available in a cold water supply to indirectly boost the pressure, and hence flow rate of

a shower water supply. The pump is preferably of a piston-type with a relatively large cylinder volume with a preference for a large diameter relative to its length. The driving cold water supply is also subsequently used to top up the water in the cold water tank so that no additional water is consumed in driving the pump than would otherwise be used in the shower. It should be appreciated that the shower system according to the invention is suitable for negative head environments, due to the nature of the pump design. In addition, the shower system is less sensitive to pressure fluctuations and temperature variations during use (compared to existing products), due to the design of the pump.

Due to the separate fluid chambers in the pump, it is not possible to fluid to mix therein. Accordingly, the present invention boosts the pressure of the hot/cold water indirectly, and it is therefore easy to control the temperature of the final shower water used for showering. In addition, the mains cold water feed used to boost the shower water pressure is fed back to the cold water supply tank, and therefore does not consume any additional cold water than would otherwise be consumed in a normal shower. Hence, the inventor believes that this allows the shower pump according to the invention to be described as being environmentally friendly because no additional energy is required to power it, and no additional water will be consumed than is otherwise required. Hence, there is no waste, a key advantage that is not currently possible with available shower systems.

According to a further aspect of the present invention, there is provided a shower pump for pumping shower water, the pump being adapted, in use, to indirectly boost shower water pressure using mains water pressure.

All of the features described herein (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined with any of the above aspects in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which:-

Figure 1 shows a schematic plan of a prior art domestic shower apparatus;

Figure 2 shows a schematic plan view of a first embodiment of a domestic shower apparatus according to the invention;

Figure 3 shows a schematic plan of a second embodiment (double booster pump) of the domestic shower apparatus according to the invention;

Figure 4 shows a schematic plan of a third embodiment (single booster pump) of the domestic shower apparatus according to the invention;

Figure 5 shows a schematic cross-sectional view of a first embodiment of a booster pump according to the invention;

Figure 6 shows a schematic cross-sectional view of the booster pump shown in Figure 5 in a first configuration;

Figure 7 shows a schematic cross-sectional view of the pump shown in Figure 5 in a second configuration;

Figure 8 shows a schematic cross-sectional view of the pump shown in Figure 5 in a third configuration;

Figure 9 shows a schematic cross-sectional view of the pump shown in Figure 5 in a fourth configuration;

Figure 10 shows a schematic cross-sectional view of the pump shown in Figure 5 in a fifth configuration;

Figure 11 shows a schematic cross-sectional view of the pump shown in Figure 5 in a sixth configuration;

Figure 12 shows a schematic cross-sectional view of the pump shown in Figure 5 in a seventh configuration;

Figure 13 shows a schematic cross-sectional view of the pump shown in Figure 5 in an eighth configuration;

Figure 14 shows a schematic cross-sectional view of a second embodiment of the booster pump according to the invention;

Figure 15 shows a schematic cross-sectional view of the pump shown in Figure 14 in a first configuration;

Figure 16 shows a schematic cross-sectional view of the pump shown in Figure 14 in a second configuration;

Figure 17 shows a schematic cross-sectional view of the pump shown in Figure 14 in a third configuration;

Figure 18 shows a schematic cross-sectional view of the pump shown in Figure 14 in a fourth configuration;

Figure 19 shows a schematic cross-sectional view of the pump shown in Figure 14 in a fifth configuration;

Figure 20 shows a schematic cross-sectional view of the pump shown in Figure 14 in a sixth configuration;

Figure 21 shows a schematic cross-sectional view of the pump shown in Figure 14 in a seventh configuration;

Figure 22 shows a schematic view of a fourth embodiment (turbine pump) of the domestic shower system according to the invention;

Figure 23 shows a schematic cross-sectional view of an impulse dampener used in the shower system according to the invention;

Figure 24 shows a schematic cross-sectional view an automatic shut-off valve in an open configuration;

Figure 25 shows a schematic cross-sectional view an automatic shut-off valve in a closed configuration;

Figure 26 shows a schematic plan of a first embodiment (double booster pump) of a domestic water supply apparatus according to the invention; and

Figure 27 shows a schematic plan of a second embodiment (single booster pump) of the domestic water supply apparatus according to the invention.

Examples

The inventor set out to produce an environmentally friendly shower system, in which the pressure and, hence, flow rate of shower water passing therethrough is adequately boosted using mains water without the need to use an electric power booster or a power shower as in prior art systems. Figure 1 shows an example of an existing shower system. Figures 2-4 show various embodiments of the shower apparatus according to the invention, and Figures 5-22 show embodiments of a booster pump.

The inventor has also found that the pump he has devised is not limited solely to boosting shower water, but can also be used generally in any domestic situation, for example, for using mains water to boost the pressure of water required for a bath, or sink, or for use in the garden. For all Figures, it should be appreciated that regulation plumbing dimensions and fittings are used throughout.

Referring to Figure 1 , there is shown a known gravity-fed shower system 1. Mains water flows from a mains water source 3 through conduit 2 to fill a cold water storage tank 4, which is normally located in the attic of a house. Cold water is fed under gravity from the cold water storage tank 4 through conduit 10 to a cold mixer tap 14. In addition, cold water is also fed under gravity from tank 4 through conduit 6 into a hot water storage tank 8, where the cold water is heated. Hot water is fed under gravity from tank 8 through conduit 12 to a hot mixer tap 16. A user adjusts the cold and hot water taps 14,16, respectively, in order to mix the water to the required temperature, and then deliver the mixed shower water under gravity through conduit 18, and out of a shower head 20. The greater the vertical distance between the shower head

20 and the water level in the cold water storage tank 4, the greater the flow out of the shower head 20. Hence, unfortunately, in some arrangements, the vertical distance is insufficient to produce suitable pressure for the flow of shower water out of the shower head 20.

Referring to Figure 2, there is shown a first embodiment of a shower apparatus 5 according to the invention. Mains water flows through conduit 2 to fill the cold water storage tank 4. The water level in the tank 4 is determined by a ball valve (not shown) located at the position where the conduit 2 meets the tank 4. Cold water is fed under gravity through conduit 6 from the cold water tank 4 into the hot water storage tank 8 where it is heated. Cold water is fed under gravity through conduit 10 into a booster pump 26. Hot water is also fed from the hot water tank 8 through conduit 12 under gravity into the same booster pump 26. The cold water and hot water are mixed inside a chamber in the booster pump 26, and the mixed hot/cold shower water exits the pump 26 via conduit 18 which leads to the shower head 20.

In order to boost the pressure of the mixed hot/cold shower water in the booster pump 26, the apparatus 5 is provided with a conduit 22, which extends between the mains water conduit 2 and the booster pump 26 along which cold mains water may flow. The mains water that is supplied to the pump 26 through conduit 22 is used to power the pump 26, which consequently boosts the pressure and flow of the hot and cold shower water mixed therein. Boosting the pressure of the hot/cold water in the pump 26 is described in detail hereinafter. Once the mains water that has been fed along conduit 22 has been used by the pump 26 to boost the pressure of the shower water, the mains water is then pumped out of the pump 26 and along a conduit 24, and up into the cold water storage tank 4. A user adjusts a mixer tap 11 located on, or downstream of, the pump 26 in order to deliver the hot/cold mixed shower water, which has been subsequently boosted in the pump 26 by pressure from the mains water, at the required temperature through conduit 18, and finally out of the shower head 20. The tap 11 can also be used to adjust the shower water flow rate.

Referring to Figure 3, there is shown a second embodiment of a shower apparatus 7. In the second embodiment of the apparatus 7, there are provided two booster pumps 28,30. Hence, this embodiment is referred to herein as a "double booster pump system". Mains water flows through conduit 2 to fill the cold water storage tank 4. Cold water is fed under gravity through conduit 6 into the hot water storage tank 8 where it is heated. Cold water is fed under gravity from tank 4 through conduit 10 to a first booster pump 30. Hot water is fed from the hot water tank 8 through conduit 12 under gravity to a second booster pump 28.

Mains water is fed from the supply 3 through conduit 22 and into both booster pumps 28,30 in order to boost the pressure of the cold shower water in the first booster pump 30, and of the hot shower water in the second booster pump 28. Hence, the mains water supplied through conduit 22 is used to power both pumps 28,30, which consequently independently boosts the pressure and flow of hot and cold shower water out of pumps 28,30 and along conduits 32,34. Once the mains water from the supply 3 has been used by the first and second booster pumps 28,30, it is then pumped from the pumps 28,30 through conduits 24 and up into the cold water storage tank 4. The user adjusts the mixer taps 14,16 to deliver the shower water, that has been boosted by pumps 28,30, at the required temperature through conduit 18 and out of the shower head 20.

Referring to Figure 4, there is shown a third embodiment of the shower apparatus 9. In the third embodiment, there is provided a single booster pump 28. Hence, this embodiment is referred to herein as a "single booster pump system". Mains water flows from the mains supply 3 through conduit 2 to fill the cold water storage tank 4. Cold water is fed under gravity from tank 4 through conduit 6 into the hot water storage tank 8 where it is heated. The hot water is fed from the tank 8 through conduit 12 under gravity to the booster pump 28. Mains water also flows through conduit 22 and into the booster pump 28, and also directly to the cold mixer tap 14. The mains water supplied through conduit 22 is used to power booster pump 28, which consequently boosts the pressure and flow of shower water out of the pump 28 along

conduit 32. Once the mains water from conduit 22 has been used by booster pump 28, it is pumped out of the pump 28 along conduit 24 to the cold water storage tank 4. The user adjusts the hot and cold mixer taps 14,16 to deliver cold water and hot water that has been boosted by booster pump 28, at the required temperature through conduit 18 and out of the shower head 20.

It should be appreciated that in each of Figures 2, 3 and 4, the cold water storage tank 4 will not over-flow because the amount of mains water that is re- circulated out of the booster pump(s) 26,28,30 into the cold water storage tank 4 is the same as the amount leaving the cold water storage tank 4. This means the water level in the tank 4 will not change. Hence, the ball valve where conduit 2 meets the tank 4 will remain closed at all times.

The following now describes the booster pump 26,28,30 in detail.

Referring to Figure 5, there is shown a cross-sectional view of a first embodiment 200 of the booster pump 26,28,30, which shows how shower water is fed from the hot and cold tanks 4,8 into the booster pump 200. In the embodiment shown in Figure 2, one booster pump 26 is used, and the shower water fed into the pump 26 is a mixture of water fed under gravity from the cold water storage tank 4 and the hot water storage tank 8 through conduits 10,12. In the embodiment shown in Figure 3, two booster pumps 30,28 are used, and shower water is fed into each pump 28,30 from conduits 10,12 under gravity from the cold and hot water storage tanks 4,8, respectively. In the embodiment shown in Figure 4, one booster unit 28 is in place, and shower water is fed into the pump 28 under gravity from just the hot water storage tank 8 through conduit 12.

As shown in Figure 5, the booster pump 200 consists of an inner unit 210 contained within an inner housing, and an outer unit 212 contained within an outer housing. Shower water (i.e. water that is used by an operator for showering) is fed along conduit 12 and/or 10 from the hot and cold water tanks 8,4, respectively, and into the booster pump 200 into channel 36 of the outer unit 212. The shower water flows along channels 36 (in two opposite directions), and through one-way valves 38 at either end of the pump 200.

Having passed through the one-way valves 38, the shower water then enters a channel 40 at each end of the pump 200. Due to the nature of the one-way valves 38, the shower water cannot flow from the channels 40 back into channels 36.

The inner unit 210 of the pump 200 defines two chambers 44 mutually separated by an inner network of channels 214 along which mains water flows to boost the pressure of the shower water. From channel 40, the shower water flows into channel 42 at each end of the pump 200, which leads to one of the central chambers 44. A double-ended piston 46 having piston heads 66,76 at either end is slideably mounted within the inner unit 210. Seals 19 form a slideable, but water-tight, seal between the housing of the inner unit 210 and the piston heads 66,76.

The respective volumes of the two chambers 44 depends on the position of the piston heads 66,76 of the double-ended piston 46 located therein. By way of example, in the configuration shown in Figure 5, piston head 66 (right hand head of piston 46) abuts the inner network of channels 214, thereby creating chamber 44 with a maximum volume, which can accommodate a volume of shower water. However, piston head 76 (left hand head of piston 46) abuts channel 42, thereby creating chamber 44 with a minimum volume, which therefore cannot accommodate any shower water. Furthermore, depending on the pressure head available in the system, the flow of shower water in channel 40 may also pass through the one way valves 48 located in channel 40 but after channel 42.

The double-ended piston 46 and its piston heads 66,76, oscillates back and forth within the pump 200, and, as a result, the shower water that occupies chambers 44 is forced back out of channel 42 and into channel 40. Due to the nature and position of the one-way valves 38,48, the shower water that is forced out of chambers 44 as a result of the oscillating piston 46, can only flow through the one way valves 48. Once the shower water has passed through the one way valves 48, it flows into a further channel 50 at the bottom of the pump 200. Due to the nature and position of the one way valves 48, once shower water has passed from channel 40 into channel 50, it is unable to

return back to channel 40. Having passed through channel 50, the shower water can then only flow through channel 52. When passing through channel 52, the shower water flow passes out of the pump 200 and through channels 32,34,18, and then to the shower head 20.

As shown in Figure 5, after leaving channels 50, a proportion of the flow of shower water also passes into an impulse dampener 54, which is shown in greater detail in Figure 23. The impulse dampener 54 is essentially a hollow- sealed vessel, typically cylindrical in shape, and is present to maintain a constant, non-pulsing flow of shower water. The outlet to the dampener 54 that leads into channel 52 must be at the base of the dampener 54 to allow the water 240 within the dampener 54 to be forced out by the air 250 within the dampener 54. Water flows through channel 52 and into the dampener 54 and also out of conduits 32,34,18 to the shower head 20. When water 240 flows into the dampener 54, the air 250 therein is compressed. When the double ended piston 46 within the pump reverses direction, the flow through the dampener 52 and out of conduits 32,34,18 is reduced. At this point, the compressed air 250 within the dampener 54 is able to force the water 240 therein out of the dampener 54, into the channel 52, and out of channels 32,34,18 to compensate for the reduction in flow. Once the double ended piston 46 is in motion again in the opposite direction, the water forced out of the dampener 54 is replaced as a result of the pump operating again. The volume of water 240 within the dampener 54 must be sufficient to maintain a continuous flow out of channels 32,34,18 whilst the piston 46 is being reversed. Hence, the dampener 54 ensures that the flow of shower water out of the shower head 20 remains constant, and does not pulsate as a result of the double-ended piston 46 changing direction as it oscillates.

Referring to Figure 6, there is shown a cross-section of the booster pump 200 as shown in Figure 5 at a first operation stage of being boosted by mains water. As shown in Figure 6, mains water is supplied to the inner network of channels 214 of the booster pump 200 through channel 22 into the centre of the device. The mains water flows into a channel 56, which has two outlets 56a, 56b. However, only one outlet 56a, 56b will be open at any one time, as

the other will be blocked by a first, sealed, internal piston 62. The first internal piston 62 is slideable within a chamber 220, and has two channels 216,218 extending transversely thereacross. The position of the piston 62, and hence, channels 216,218 within the chamber, determines whether outlet 56a or outlet 56b is open, and whether mains water flows towards piston head 66 or piston head 76. For example, in Figure 6, outlet 56b is shown as being open with the channel 218 in alignment therewith. Hence, because of the position of the piston 62, the mains water flow can only travel from channel 56 into channel 60 through channel 218 in the piston 62. The mains water flows through channel 60 into channel 64. The outlet to channel 64 is covered by piston head 66 of the double ended piston 46. Consequently, mains water pressure builds up behind the piston head 66, and thereby forces the double-ended piston 46 to move from left to right as indicated by arrow "A", until it reaches the position shown in Figure 7.

In addition to passing into channel 60 through channel 218 in the piston 62, mains water also passes from conduit 22 into a separate channel 58 (indicated by the dashed line in Figure 6). Mains water flows through channel 58 and into a channel 68, which has two outlets 68a, 68b. However, only one outlet 68a, 68b will be open at any one time, as the other will be blocked by a second internal piston 74. The second internal piston 74 is slideable within a chamber, and includes two channels extending thereacross. The position of the piston 74, and hence, the two channels within the chamber, determines whether outlet 68a or outlet 68b is open, and hence, the direction of mains water flow. As a result of the position of second piston 74, the flow of mains water passes through channel 68 into channel 70. From channel 70, the flow passes into channel 72 where the pressure builds up behind the first internal piston 62 maintaining its position, and allowing the flow of mains water to continue behind the piston head 66.

Referring to Figure 7, there is shown a cross-section of the booster pump 200 at a second operation stage of being boosted by mains water being fed thereto along conduit 22. As a result of the pressure build up behind piston head 66, the double-ended piston 46 moves from left to right in the direction of

arrow "A". During this process, the shower water fed into chamber 44 on the right hand side of the pump from conduit 10,12 is forced under pressure out through channel 42. At the same time, piston head 76 also moves from left to right in the direction of arrow "A", and chamber 44 on the left hand side of the pump increases in volume and fills with shower water fed in through conduit 10 and/or 12. As a result of double-ended piston 46 moving from left to right, piston head 76 on the left-hand end of the double-ended piston 46 abuts left hand end 74a of the second internal piston 74. This causes the piston 74 to slide from left to right within its corresponding chamber, thereby changing its internal position to that shown in Figure 8.

Referring to Figure 8, there is shown a cross-section of the booster pump 200 at a third operation stage of being boosted by mains water being fed thereto along conduit 22. As a result of piston head 76 moving the internal position of second internal piston 74, from left to right, the right hand end 74b of piston 74 now extends beyond the surface of the network of channels 214. The result of piston 74 shifting position is that the outlet in channel 68 has also moved such that the flow of mains water cannot pass from channel 68 into channel 70 and build up in channel 72. Instead, the flow of mains water now passes from channel 68 to channel 78 and into channel 80. As a result of the pressure building up in channel 80 rather than in channel 72 (as in the second operation stage), the sealed internal second piston 62 will be shifted from left to right within chamber 220 to the position shown in Figure 9.

Referring to Figure 9, there is shown a cross-section of the booster pump 200 at a fourth operation stage of being boosted by mains water being fed thereto along conduit 22. As a result of the first internal piston 62 being shifted from left to right, the outlet to channel 56 has now changed with the channel 216 now being aligned with channel 84, such that the flow of mains water through channel 56 now passes into channel 84 rather than into channel 60. As a result of the first piston 62 moving from left to right, the mains water within channel 72 is forced out of channel 72 and into channel 82, and then out of channel 24 which leads the mains water to the cold water storage tank 4. The build up of mains water pressure is no longer in channel 72 but now in

channel 80, and thus the new position of 62 is maintained due to water pressure therein. Mains water now flows through channel 22 into channel 56 then into channel 84 and finally into channel 86 where it builds up pressure behind piston head 76, i.e. the left hand side of the double-ended piston 46. This build up of pressure behind piston head 76 causes the double-ended piston 46 to move from right to left in the direction indicated by arrow "B", as shown in Figure 10.

Referring to Figure 10, there is shown a cross-section of the booster pump 200 at a fifth operation stage of being boosted by mains water being fed thereto along conduit 22. As a result of piston 46 moving from right to left, the mains water that built up behind piston head 66, which initially caused it to move from left to right, is forced out through channel 64, then through channel 60, and out of channel 24, where it is re-circulated to the cold water storage tank 4. As a result of the double-ended piston 46 moving from right to left, the shower water that filled the left hand chamber 44 of the pump is forced out of the pump under pressure and out of the shower head 20. As a result of the piston 46 moving from right to left, the right hand chamber 44 increases in volume and becomes filled with further shower water fed in through channel 10 and/or 12. As a result of piston 46 moving from right to left, the piston head 66 abuts the right hand end 74b of the internal piston 74, and causes it to shift from right to left within its chamber to the position shown in Figure 11.

Referring to Figure 11 , there is shown a cross-section of the booster pump 200 at a sixth operation stage of being boosted by mains water being fed thereto along conduit 22. As a result of internal piston 74 being moved by piston head 66 from right to left, water flow through the internal channels causes the internal piston 62 to also move in chamber 220 from right to left to the position as shown in Figure 12.

Referring to Figure 12, there is shown a cross-section of the booster pump 200 at a seventh operation stage of being boosted by mains water being fed thereto along conduit 22. As a result of internal piston 62 moving from right to left, the direction of movement of the double ended piston 46 is also moved

from left to right, as shown in Figure 13, by re-directing the flow of mains water through channel 60.

Referring to Figure 13, there is shown a cross-section of the booster pump 200 at an eighth operation stage of being boosted by mains water being fed thereto along conduit 22.

Hence, it will be appreciated from Figures 5-13 that the first embodiment of the pump 200 draws shower water in via inlet 10,22, and pumps it out through outlet 18,32,34 under pressure generated from mains water 22. The mains water feeds into the pump and flows along the system of internal channels 214 and causes the two internal pistons 62,74 to oscillate from left to right and from right to left within their respective chambers in order to maintain mains water flow into the left and right sides of the pump behind piston heads 66,76. The cyclic movement of mains water behind piston heads 66,76 causes the double ended piston 46 to continually oscillate from left to right, and from right to left as indicated by the double headed arrow "C". As the piston 46 oscillates, shower water is forced out of the pump through 18,32,34 to the shower head 20. The sequence of events of oscillating pistons 46,74,62 continues until the user turns off the shower at the mixer tap 14,16,11.

Referring to Figure 14, there is shown a second embodiment 300 of the booster pump 26,28,30 according to the invention. The general system of conduits and channels (i.e. inlet 10,12 and outlet 18,32,34 for shower water, and inlet 22 and outlet 24 for mains water) and of the oscillating double ended piston 46 of the second embodiment 300 is similar to the first embodiment 200 of the pump shown in Figure 5. However, the internal system of channels of the pump 300, which are different, are described hereinafter.

Referring to Figure 15, there is shown a cross-section of the booster pump 300 at a first operation stage of being boosted by mains water being fed thereto along conduit 22. Shower water is fed into the pump via channel 10,12, around channel 36, through one-way valve, into channel 42 and then to chamber 44. From chamber 44, the shower water is forced back out through channel 42, through one-way valve 48 and into channel 50. Channel 50 feeds

to channel 52, where the shower water exits the pump 300. Shower water is passed into the impulse dampener 54, and then back out to the shower head 20 via channels 18,32,34.

Mains water is supplied to the pump 300 through channel 22. The mains water flows into channel 88, which has two outlets 88a, 88b. However, only one outlet will be open at any one time, as the other will be blocked by a first, sealed, internal piston 92, which has two channels extending therethrough 302,304. Piston 92 is slideable within a correspondingly shaped chamber 306. Hence, due to the position of the first piston 92 in the chamber 306, the channel 302 is aligned with channels 88 and channel 90. Hence, mains water flow can only travel from channel 88 into channel 90 through outlet 88a. The mains water flow passes through channel 90 and into channel 94 as shown in Figure 15.

As shown in Figure 15, the outlet to channel 94 is covered by the left piston head 76 of the double ended piston 46. Consequently, the pressure build up created by mains water behind piston head 76 forces the double ended piston 46 to move from right to left as indicated by arrow "D" to the position shown in Figure 16.

Referring to Figure 16, there is shown a cross-section of the booster pump 300 at a second operation stage of being boosted by mains water being fed thereto along conduit 22. As a result of the pressure build up behind left hand piston head 76, the double ended piston 46 moves from right to left. During this process, the shower water fed into chamber 44 on the left hand side of the pump 300 is forced out under pressure through channel 42, through valve 48, and eventually out through channel 52 out of the pump 300. Insodoing, chamber 44 on the right hand side of the pump 300 increases in volume and fills with more shower water fed in through channel 10 and/or 12. As a result of the double ended piston 46 moving from right to left, piston head 66 abuts a second internal piston 96, which protrudes beyond face 308 of the internal system of channels. As piston head 66 continues to push the second internal piston 96 inwardly from right to left, a spring 97 attached to, or in contact with,

piston 96 is compressed behind the first sealed, internal piston 92, as shown in Figure 17.

Referring to Figure 17, there is shown a cross-section of the booster pump 300 at a third operation stage of being boosted by mains water being fed thereto along conduit 22. Once the second internal piston 96 cannot be pushed any further by the piston head 66, the spring 97 attached to, or in contact with, the piston 96 is fully compressed. As shown in Figure 17, the first piston 92 has two slots 101 , 103 into which a ball bearing 102 is urged under the biasing action of a spring 99. When spring 97 is fully compressed due to the piston 96 being pushed inwardly, there is sufficient energy in the spring 97 to displace the ball bearing 102 from the slot 101 allowing the sealed internal piston 92 to shift from right to left. As the piston 92 moves from right to left, it moves channel 302 and hence, channel 88 out of alignment with channel 94. The ball-bearing is eventually urged by the spring 99 into slot 103. As a result of piston 92 shifting from right to left, a third internal piston 104 is also urged from right to left, and insodoing, outlet 88a becomes closed off and outlet 88b becomes open and aligned with 304 and 98 as shown in Figure 18.

Referring to Figure 18, there is shown a cross-section of the booster pump 300 at a fourth operation stage of being boosted by mains water being fed thereto along conduit 22. The flow of mains water now travels from channel 22 into channel 88, and through outlet 88b into channel 98 through channel 304 in piston 92. From channel 98, the mains water flow passes into channel 100, where the pressure builds up behind the right hand piston head 66 of piston 46. As a result of the pressure build up behind piston head 66, piston 46 moves from left to right as indicated by arrow "E" to the position shown in Figure 19.

Referring to Figure 19, there is shown a cross-section of the booster pump 300 at a fifth operation stage of being boosted by mains water being fed thereto along conduit 22. As a result of the piston 46 moving from left to right, the mains water that had built up behind piston 76 to move piston 46 from right to left, is exhausted from the pump 300 through channel 94, and then out of channel 24, from where it is re-circulated back to the cold water storage

tank 4. As a result of the piston 46 moving from left to right, shower water fed into the right hand chamber 44 is forced out of 42 under pressure and through valve 48 to eventually exit the pump 300 via channel 52. At the same time, the left hand chamber 44 increases in volume and fills with further shower water drawn in through channel 10 and/or 12.

Referring to Figure 20, there is shown a cross-section of the booster pump 300 at a sixth operation stage of being boosted by mains water being fed thereto along conduit 22. As piston head 76 abuts the third internal piston 104, a spring 105 attached to, or in contact with, the third piston 104 becomes compressed between the first internal piston 92 and the third piston 104. Once piston head 76 has pushed the third internal piston 104 inwardly as far as it can go, there is sufficient energy in spring 105 to dislodge the ball bearing 102 from out of slot 103 against the biasing action of spring 99. Consequently, the second, sealed, internal piston 92 is moved from left to right, simultaneously urging piston 96 from left to right to the position as shown in Figure 21.

Referring to Figure 21 , there is shown a cross-section of the booster pump 300 at a seventh operation stage of being boosted by mains water being fed thereto along conduit 22. As a result of piston 92 shifting from left to right, channel 304 moves out of alignment with outlet 88b and channel 100, and is replaced by channel 302 which now aligns with outlet 88a and channel 94. Hence, the outlet 88a of 88 is open, and thus the above sequence of events repeat, starting with the configuration shown in Figure 15.

Hence, it will be appreciated from Figures 14-21 that the second embodiment of the pump 300 draws shower water in via inlet 10,22, and pumps it out through outlet 18,32,34 under pressure generated from mains water 22. The mains water feeds into the pump and flows along the system of internal channels and causes the three internal pistons 92,96,104 to oscillate from left to right and from right to left within their respective chambers in order to maintain mains water flow into the left and right sides of the pump 300 behind piston heads 66,76. The cyclic movement of mains water behind piston heads 66,76 causes the double ended piston 46 to continually oscillate from left to right, and from right to left as indicated by the double headed arrow "F". As the

piston 46 oscillates, shower water is forced out of the pump through 18,32,34 to the shower head 20 via impulse dampener 54. The sequence of events of oscillating pistons 92,96,104,46 continues until the user turns off the shower at the mixer tap 14, 16, 11.

Referring to Figure 22, there are shown an alternative apparatus and method for using mains water to boost flow and pressure of shower water within a shower system. The above description explains the use of mains water and a piston pump 26,28,30 to boost the pressure and flow delivered out of a shower system. An alternative method of boosting the water pressure and flow out of the shower system is to use mains water to drive a turbine 150 attached to a centrifugal pump 152. The type of turbine 150 could be, but is not restricted to, a Pelton turbine, or a similar impulse turbine. Mains water flows from conduit 22 into the turbine 150 causing it to rotate. Mains water leaves the turbine 150 via conduit 24 and returns back to the mains water storage tank 4. A sealed bearing and shaft assembly 156 translates the rotational energy from the turbine 150 to a pump head 154 of the centrifugal pump 152. Hot, cold, or mixed temperature shower water is fed into the centrifugal pump 152 via conduits 10 and/or 12, and the centrifugal pump boosts the pressure of the shower water using the energy produced by the turbine 150.

Referring to Figures 24 and 25, there is shown a schematic cross-sectional view of an automatic shut-off valve 400, which is used in the shower systems described in Figures 2, 3 and 4. The valve 400 is used to automatically shut off further mains water from flowing into the pump 26,28,30 when the shower and pump are not in use. This prevents the risk of mains water leakage from the pump, which could otherwise occur due to constant pressure of mains water into the pump, when shower water is not being pumped thereby.

As illustrated in Figure 2, the automatic shut off valve 400 is positioned in the mains water supply channel 22 upstream of where the mains water supply enters the pump 200,300, and is ideally integrally formed with the pump. The valve 400 is closely arranged with channel 52, along which shower water exits the pump, which leads to conduits 18,32,34 and to the mixer taps 14,16, and

ultimately to the shower head 20. It should be noted that there is no mixing between the mains water or the shower water inside the valve 400 due to a flexible, diaphragm 404, which separates channel 22 with channel 52 as shown in Figure 24. The valve 400 is not shown in Figures 3 and 4, for clarity.

Referring to Figure 24, the automatic shut-off valve 400 is shown in the open configuration, with the flexible diaphragm 404 forming a planar barrier between channel 22 (for mains water) and channel 52 (for shower water). The automatic shut off valve 400 is in this position when the shower mixer taps 14,16,11 are open allowing shower water to pass therethrough. The internal cross-section of the valve 400 tapers inwardly through a "bottle neck" region 402 through which water may pass, and then follows a 90 degree turn from where it connects to the pump as feed 22. When the valve is open, mains water flow therethrough is unrestricted, and so mains water flows through the shut-off valve 400 as indicated by arrow "F", and into the body of the pump. Mains water exits the pump along channel 24 and is fed to the cold water storage tank 4.

When the pump is on, shower water is pumped out of the chambers 44, through valves 48, and out through channels 50,52 and then to the impulse dampener 54. The shower water flows out of the pump via the impulse dampener 54, and continues to the shower head 20. However, as shown in Figure 24, channel 52 forms a T-section with a short arm section 420 extending towards conduit 22. A dividing wall 406 extends across the lumen of the arm section 420, and has an aperture 408 extending therethrough. A small proportion of the shower water exiting the pump in channel 52 passes through the aperture 408, which leads to small chamber 422 behind the flexible diaphragm 404. Once the shower water flow occupies the chamber 422, pressure builds up behind the diaphragm 404. However, the shape of the diaphragm 404 remains unchanged due to the high pressure on the opposite side caused by the mains water supply 22 feeding into the pump, which urges the diaphragm to maintain the planar configuration extending across the arm section 420, as shown in Figure 24. Hence, the shut-off valve 400 remains

open due to the high pressure of the mains water flowing through the conduit 22.

Referring to Figure 25, the automatic shut-off valve 400 is now shown in the closed configuration. This occurs automatically and is caused by closing the mixer taps 14, 16, 11 As a result of closing the taps 14,16,11 and stopping the shower, the shower water pressure in chamber 422 behind the diaphragm 404 increases as no shower water exits the shower. Due to the area of the diaphragm 404 facing the chamber 422 being greater than the area of the diaphragm 404 facing conduit 22 (as shown in Figure 25), the flexible diaphragm 404 is flexed towards the taper section 402 in conduit 22. Hence, the diaphragm is displaced to the point where it seals against the exit to the "bottleneck", which effectively forms a valve seat. As a result, the mains water supply 22 to the pump is automatically cut off. Once the mixer taps 14,16,11 are opened again, the pressure behind the diaphragm 404 is released as shower water is drawn towards the shower head 20, and the bottle neck 402 is opened again thereby allowing more mains water to flow therethrough.

In summary, advantages of the shower apparatus reside in the manner in which pressure from the mains water supply 3 is used to boost the pressure and hence flow rate of shower water, i.e. either cold water, hot water, or mixed hot/cold water. The booster pump 26,28,30 is able to harness the high pressure of mains water to indirectly increase the pressure of the shower water, without mixing the mains water and shower water before the shower water is fed to the shower head 20. This means the power can be boosted without experiencing any disadvantageous temperature fluctuations in the shower water.

The dampener 54 serves to maintain a constant flow rate of shower water out of the pump. It becomes partly filled with shower water 240 and air 250 during use of the pump 200, 300. When the shower water flow passes into the dampener 54, the air therein is compressed. When the direction of the double- ended piston 46 is reversed during oscillation thereof, the flow of shower water out of channel 52 momentarily drops. At such a time, the shower water in the dampener 54 is forced outwardly therefrom by the compressed air

within the dampener 54, ensuring a constant pressure and flow of shower water.

The design of the booster pump 200 is also advantageous as the interrelationship between the network of channels 214, and the various internal pistons 62,74,46 make it impossible for the pressure either side of the double- ended piston 46 to equalise, which would otherwise cause the pump to stop pumping. The same is true for pump 300 having the three internal pistons 92,96,104, which are all in a biased relationship with each other via springs 97,99, 105. Furthermore, the biased ball-bearing 102 is urged into slot 101 or 103 depending on the position of the piston 92 thereby ensuring the correct alignment of channel 88 with either channel 94 or 100. Finally, the incorporation of the automatic shut-off valve 400 in the pump is a useful feature for ensuring the mains water flowing into the pump along conduit 22 is automatically stopped when the taps 14,16,11 are closed. This reduces the likelihood of leakage from the pump.

The inventor have also found that the booster bump 28,30 of the invention can be incorporated into any domestic water system, and is not solely limited to use for boosting shower water.

Referring to Figure 26, there is shown an embodiment of a domestic water apparatus 600. In the first embodiment of the apparatus 600, there are provided two booster pumps 28, 30. Hence, this embodiment is referred to herein as a "double booster pump system". Mains water flows from a mains supply 3 through conduit 2 to fill the cold water storage tank 4. Cold water is fed under gravity through conduit 6 into the hot water storage tank 8 where it is heated. Cold water is fed under gravity from tank 4 through conduit 10 to a first booster pump 30. Hot water is fed from the hot water tank 8 through conduit 12 under gravity to a second booster pump 28.

Mains water is fed from the supply 3 through conduit 22 and into both booster pumps 28,30 in order to boost the pressure of the cold water in the first booster pump 30, and of the hot water in the second booster pump 28. Hence, the mains water supplied through conduit 22 is used to power both pumps

28,30, which consequently independently boosts the pressure and flow of hot and cold water out of pumps 28,30 and along conduits 32,34. Once the mains water from the supply 3 has been used by the first and second booster pumps 28,30, it is then pumped from the pumps 28,30 through conduits 24 and up into the cold water storage tank 4. The user adjusts the hot and cold taps 428,426 respectively to separately deliver the water, that has been boosted by pumps 28,30, out of the taps 428, 426 and into the bath, sink, or out of the hose pipe, sprinkler, water fountain etc.

Referring to Figure 27, there is shown a second embodiment of the domestic water apparatus 800. In the second embodiment, there is provided a single booster pump 28. Hence, this embodiment is referred to herein as a "single booster pump system". Mains water flows from the mains supply 3 through conduit 2 to fill the cold water storage tank 4. Cold water is fed under gravity from tank 4 through conduit 6 into the hot water storage tank 8 where it is heated. The hot water is fed from the tank 8 through conduit 12 under gravity to the booster pump 28. Mains water also flows through conduit 22 and into the booster pump 28, and also directly to the cold tap 426. The mains water supplied through conduit 22 is used to power booster pump 28, which consequently boosts the pressure and flow of water out of the pump 28 along conduit 32. Once the mains water from conduit 22 has been used by booster pump 28, it is pumped out of the pump 28 along conduit 24 to the cold water storage tank 4. The user adjusts the hot and cold taps 428,426 to separately deliver cold water and hot water that has been boosted by booster pump 28, out of the taps 428, 426 and into the bath, sink, or out of the hose pipe, sprinkler, water fountain etc.