GB2191245A

GB2191245A - Water powered shower booster pump

Info

Publication number: GB2191245A
Application number: GB08712725A
Authority: GB
Inventors: James David Coleman; Anthony Gregory Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-05-30
Filing date: 1987-05-29
Publication date: 1987-12-09
Anticipated expiration: 2007-05-29
Also published as: GB8613239D0; GB8712725D0; GB2191245B

Abstract

A unit as shown in Fig. 1 uses the cold water supply to boost the energy of the hot water supply, by means of the Coanda Effect. The cold water supply flows from the annular nozzle over the Coanda surface 3. Hot water is entrained from its inlet connection 12. The inlet and exit conditions of the two flows can be altered and maximised thus producing a suitable shower of warm water from a variety of conditions. <IMAGE>

Description

SPECIFICATION Water powered shower booster pump We, James David Coleman BSc., of The Oast House, Little Trodgers, Lake Street, Mark Cross, Crowborough, East Sussex, TN6 3NT, and Anthony Gregory Smith BSc., of 51 Frankland Close, Weston, Bath, BA1 4EJ, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to the use of a cold water powered pump primarily used to boost the flow rate and pressure of the hot water supply for a shower unit.

There are many reasons for wanting to install a shower facility within a house. These include economy, hygiene and convenience.

Currently there are various forms of shower on the market, the most simple design being one which uses the normal household water supply with a hand held shower head attached to the hot and cold bath taps. These may either take the form of an adaptor or an add on accessory. A very common problem with these systems is that the supply head of the hot water is usually much less than that of the cold water supply. This means that adjustment of the cold water can be critical and the shower can suddenly become scalding hot or very cold. Furthermore, if a tap somewhere else in the system is opened or closed, the temperature may suddenly change. This is especiaily a problem when the shower is being used by the old or young. Another problem is when the lack of pressure in the hot water system is such that a simple shower can not be installed at all.These problems arise because U.K. building regulations dictate that the hot water tank must have a break from the inlet of the cold water main in order to prevent any drain back of contaminated water into the mains. The hot water tank can at best only be situated in the roof space, and this can not give a supply pressure similar to the cold water. Some shower manufacturers offer an electrical booster pump to solve the problem. These are expensive and noisy. In many cases they also require a qualified plumber and electrician to install them.

It is possible to install a totally electrical shower system. These use the mains cold water supply. The water passes through a coil heat exchanger and is delivered direct to the shower head. These systems are adequate, but often can not deliver the force of shower that many people require. They require a direct mains supply from the fuse box of 7 or 8 KW. The shower unit has to be fused separately and the wires have to be buried in the wall. It is consequently an expensive item to install. A further problem with these showers is that the maximum pressure and temperature of the shower delivery varies with the seasonal temperature. In the winter, the mains water is very cold and consequently the flow rate has to be reduced in order to allow the water to reach the desired temperature.

The need arises for a system whereby a normal hot water supply can be modified to provide an adequate shower without the considerable expense of electrical booster pumps and/or electrical showers.

The present invention provides a solution to the problem. A pump has been developed that uses the Coanda effect. The cold water mains supply is channelled over a Coanda surface in the form of a Coanda jet. The hot water is admitted into the unit as a secondary flow.

The Coanda jet of cold water entrains the hot water supply and mixes with it. The subsequent flow is then passed through the necessary pipe work to a suitable shower head.

The pressure difference of the two supplies allows a large improvement of the hot water flow. A valuable feature is that the system is able to cope with pressure fluctuations of the cold water supply. The hot water supply pressure is usually low but constant. As the cold water pressure changes, so will the rate of entrainment of the hot water. In this way a nearly constant temperature shower will be maintained. The pump is simple in design, construction and use. It requires no electricity.

The feature of maintaining a constant temperature is peculiar to this type of pump. Another feature is that the unit ensures very good mixing of the hot and cold flows before exit from the shqwer head. There are other means by which the cold water supply may be used to boost the hot water flow rate but it is felt that the Coanda effect provides the most effective solution.

Primarily it is envisaged that the unit will consist of an adaptor that will fit onto the bath taps. There are however several other applications. The unit could be incorporated in the initial plumbing for a house, or a unit could be designed such that it could be plumbed in as an extra and not affect the working of the normal bath taps. Use of the unit for a shower is not the only application.

There are situations that arise whereby domestic appliances require plumbing in to a separate hot and cold water supply. Most devices specify a minimum head of approximately three metres. In cases where the hot water tank is not able to meet this specification, it could be possible to install a unit to provide the necessary boosted flow of hot water. Old plumbing systems are often prone to this problem, and the unit would provide a cheap solution to this awkward situation.

A prototype construction according to the invention is more particularly described with reference to the accompanying drawing wherein: Figure 1 is a sectional elevation of the basic pump unit.

Referring now to the drawing, Fig. 1, a section is shown of an axisymmetric version of the unit which comprises four main parts; these being the inlet chamber body 1, the unit inlet 2, the Coanda surface 3, and the divergent section 4. The inlet chamber body 1 is fixed to the divergent section 4 via an interference fit at 5 which provides sealing. The Coanda surface 3 is also fixed to the divergent section 4 by an interference fit.

The advantage of producing the Coanda surface and divergent section in separate pieces is that different Coanda surface shapes can be used without reproducing the divergent section. This has been useful during the development stages of the work. The interference fits may be positively secured although to date this has not been found to be necessary. The unit inlet is secured via the screw thread on its inner surface which mates with a corresponding thread on the inlet chamber body.

This method of attachment also enables the nozzle exit size to be altered as required. The inlet chamber 6 of the unit is supplied with the cold water supply through a manually operated on/off valve 7. The water then passes via the passages 8 into the nozzle supply chamber 9, and exits the annular nozzle 10 which is formed by the unit inlet 2 and the top of the Coanda surface 3. The nozzle exit surfaces are angled at slightly less than 90 degrees to the unit axis. The cold water, which may also be referred to as the primary flow, forms a jet which attaches to the Coanda surface 3. In following this surface which may be smooth or stepped the jet entrains a secondary flow. The primary and secondary flows continue to mix in the divergent section 4 before entering a pipe 11. This resultant flow produces suction at the unit inlet 2 which enables the unit to pump the hot water supply from its inlet connection 12. The ability to control the nozzle size as detailed above allows the efficiency of the unit to be precisely controlled and optimised. In this way, the unit can cope with a wide range of inlet conditions for both the hot and cold water supply. To allow extra control, a variable geometry shower head may be fitted to the system. This can be altered to vary the back pressure on the unit.

Various modifications may be made within the scope of this invention. For example the unit may be of a rectangular section; the number of parts used may be reduced, perhaps by casting; the nozzle angular position relative to the body axis may be varied; the unit inlet and Coanda surface shapes may be varied in order to optimise performance.

Claims

1. A unit which transfers energy from one water supply to another water supply.

2. A unit according to claim 1 in which the two supplies are allowed to mix.

3. A unit according to claim 1 in which there is a mixing region between the Coanda surface and the divergence.

3. A unit according to claim 1 in which the two supplies are not allowed to mix.

4. A unit according to claims 1 and 2 in which the more energetic supply is used as the primary flow in a jet pump and in which the secondary supply is entrained by said pump.

5. A unit according to claims 1,2 and 4 in which the jet pump makes use of the Coanda effect.

6. A unit according to claim 5 in which the Coanda effect is maximised by using an initial Coanda surface followed by an immediate divergence.

7. A unit according to claim 5 in which there is a mixing region between the Coanda surface and the divergence.

8. A unit as described in any of the preceding claims which is used to provide a domestic shower of water.

9. A unit in which the flow rate of both supplies can be regulated.

10. A unit in which the resultant flow can be regulated after energy has been transferred.

11. A unit as in the drawing fig. 1.

CLAIMS Amendments to the claims have been filed, and have the following effect: Claims 1 to 8 above have been deleted or textually amended.

New or textually amended claims have been filled as follows:- Claims 8 to 9 above have been re-numbered as 4 to 5 and their appendancies corrected.

1. A unit in which a supply of water is allowed to mix with and transfer energy to another supply of water by means of the Coanda effect for the purposes of creating a domestic shower.

2. A unit according to claim 1 in which the Coanda effect is maximised by using an initial Coanda surface followed by an immediate divergence.