GB2160627A - Apparatus for supplying instantaneous hot water for washing purposes - Google Patents

Abstract

An apparatus (1) for supplying instantaneous hot water for washing purposes has an inlet (4) for water from a water reservoir; an electrically operated pump (6) for assisting the flow of the water through a chamber (8); and an outlet (10) for the water. The chamber has a heating element adapted to heat the water as it passes therethrough. The apparatus also has a first means (16, 16a, 16b) responsive to a first predetermined pressure of water through the chamber for actuating the pump; and a second means (16, 16a, 16b) responsive to a second predetermined pressure of water through the chamber for actuating the power supply to the heater. The first predetermined pressure is at least about 1.38kPa and the second predetermined pressure is about 48.25kPa. <IMAGE>

Description

SPECIFICATION Apparatus for supplying instantaneous hot water for washing purposes This invention relates to an apparatus for supplying instantaneous hot water for washing purposes. In particular, it relates to an apparatus for heating water wherein the water is heated as it flows through a chamber having an electric heating element therein.

Such apparatus is well known and provides instantaneous hot water for use in showers.

Water may be fed to the apparatus directly from a mains supply or from a reservoir housed in the building having the apparatus therein.

The present invention does not concern itself with a water supply directly from said mains but rather from said reservoir.

In the known apparatus, problems arise insofar as the minimum pressure of water supply required to operate the apparatus is in the region of 103.41kPa (15 psi) and this pressure is obtained only when the head of water is at least 9m. It is usually necessary to ensure that the electricity supply to the heating element is cut off immediately the flow of water ceases or falls below a predetermined minimum rate. However, a certain volume of water remains in the apparatus, particularly in the chamber. Because the water in the chamber absorbs the heat from the cooling heating element, the temperature of the water in the chamber can increase to an unacceptably high level which, if the apparatus is immediately reactivated, water at a dangerously high temperature will be dispensed.Furthermore, the flow valve, which ultimately controls the temperature of water emitting from the known apparatus, is located between the heating element and the water outlet. In the event of a flow valve failure leading to a closed outlet, a potential hazard may be created in the event that if the thermostat fails, the heating element would continue to operate, thereby heating the stationary water which would be rapidly converted to steam thereby causing the explosive rupturing of the flow lines. It is an object of the present invention to overcome these problems.

The invention therefore provides an apparatus for supplying instantaneous hot water for washing purposes which apparatus comprises an inlet for water from a water reservoir; an electrically operated pump for assisting the flow of the water through a chamber having a heating element adapted to heat the water as it passes therethrough; an outlet for the water; a first means responsive to a first predetermined pressure of water through the chamber for actuating the pump; and a second means responsive to a secon predetermined pressure of water through the chamber for actuating the power supply to the heating element.

The invention will be understood in greater detail from the following description of a preferred embodiment thereof given by way of example only and with reference to the accompanying drawing which is a plan view of an apparatus according to the invention.

Referring now to the drawing, there is shown an apparatus 1 according to the invention. The apparatus 1 comprises a base 2 having a duct 3 attached integrally thereto for housing a water inlet pipe 4 and electricity cables (not shown) which cables pass from the duct 3 to the base 2 via a grommet 5. The water pipe 4 leads into an electrically operated pump 6 having a conventional cooling fan 7. The pump 6, which is of the drain type, is connected via a valve 9 to a chamber 8 having a heating element therein. The chamber 8 is mounted on the base 2 by means of screws 2a. The chamber 8 may be of a known type but is preferably of the type disclosed in the Specification of co-pending Irish Patent Application No. 1 557/84.

Leading from the chamber 8 is a water outlet pipe 10 which is connectable to a flexible pipe (not shown) attached to a shower head (also not shown).

Projecting out of the chamber 8 are electrical connections 11 for the heating element housed in the chamber 8. The chamber 8 has a conventional thermostat 1 2 which monitors the temperature of water flowing therethrough which thermostat 1 2 is electrically connected to the heating element so as to cut off the supply of electricity should the temperature of the water exceed approximately 53 ( + 2"C).

Other items shown in the drawing are a relay 13, electrical connectors 14 and a switch 15.

The electric cables are not shown as a person skilled in the art would have no difficulty in making the appropriate electrical connections.

A first means responsive to a first predetermined pressure of water through the chamber for controlling the supply of electricity to the pump 6 and a second means responsive to a second predetermined pressure of water through the chamber 8 for controlling the supply of electricity to the heating element of the chamber 8 are housed in a housing 1 6.

Essentially, the housing 1 6 comprises a modified known pressure response switch. The pressure switch is basically of the type known as Eaton PD4 made by Eaton Controls Division of 1-20070 Borgo S. Giovanni, Italy. The PD4 pressure switch comprises a diaphragm which is adapted for movement against biasing rings 1 6a in response to pressure changes from water located in a tube 1 7 whch connects the housing 1 6 with the chamber 8.

The pressure switch PD4 has been modified so that the water inlet tube 1 7 has a diameter of about 5mm which is considerably in excess of the usual diameter of about 0.5mm of the inlet tube used in such pressure switches. The PD4 pressure switch operates such that when the first predetermined pressure of water through the chamber 8 is achieved the diaphragm operates a first set of contacts and when the second predetermined pressure of water flows through the chamber 8, the diaphragm operates a second set of contacts.

The terminals 1 6b of the contacts are illustrated on the housing 16. The first set of contacts is electrically connected to the pump 6 and the second set of contacts is electrically connected to the heating element via the relay 13.

To use the apparatus 1, the valve 9 is opened so that water flows passively into the chamber 8 and to the outlet pipe 10. A head of water as little as 50mm and at a pressure of as low as 1.38kPa (0.2psi) will activate the first set of contacts of the pressure switch 1 6 thereby actuating the pump 6.As soon as the pump 6 operates, the pressure of water flowing through the chamber 8 will increase substantially to at least 48.25kPa (7psi) when the second set of contacts is activated thereby switching on the heating element in the chamber 8 via the relay 1 3. If for any reason, including shutting the valve 9, the pressure of water passing through the chamber 8 falls below 48.25kPa (7psi), the second set of contacts will be deactivated thereby shutting off the electrical supply to the heating element but the pump 6 will continue to operate.

Thus, the heating element is cooled in a stream of water which enables the residual heat of the element to be dissipated quickly and safely. As the water pressure falls further to 1.38kPa the first set of contacts is deactivated thereby shutting of the electrical supply to the pump 6 until finally, the valve 9 is closed completely thereby stopping the flow of water through the apparatus 1.

From the drawing, it will be appreciated that a very simple plumbing layout is possible in such an apparatus and if the chamber 8 and associated heating element is of the type disclosed in the Specification of Irish Patent Application 1557/84 referred to above is used, the heating element can have a rating of up to 8.4kW. Furthermore, the layout provides for minimum resistance to the flow of water and therefore the pump 6 can have a relatively low pumping machines. In addition, the pressure switch can be of any suitable type which will have a relatively large diameter tube 1 7 to enable a rapid response to changes in pressure to take place.

Furthermore, in the apparatus 1, the valve 9 serves to initiate the flow of water through the apparatus 1 which flow activates the pump 6 and the heating element as described. Thus, the need for several independent manually operated switches necessary to operate the pump 6 and the heating element has been eliminated. In addition, the safety features which are desirable in such an apparatus are simple and effective. By locating the valve 9 downstream of the pump 6 and upstream of the chamber 8, in the unlikely event of failure of the valve 9 and the thermostat 1 2 resulting in stationary water being heated, the resulting steam can escape passively through the outlet 10.

A switch 1 5 may be provided which will electrically disconnect one or both of the elements 88 or 88b and 88c, as appropriate, to enable the user to have a cold shower or to accommodate the intake of water at a relatively higher temperature due to seasonal variations.

In the case of the chamber 8 in which the heating element has a rating of less than 4kW, the relay 1 3 may be omitted as the second set of contacts of the pressure switch 1 6 may directly switch the heating element on. The use of a heating element having a rating below 4kW may be appropriate in installations when the temperature of the incoming water is relatively high.

In the case of a heater 8 having the second heating element and wherein the heating elements thereof each has a rating below 4kW, the relay 1 3 may be omitted and the first heating element may be switched on directly by means of the first set of contacts of the pressure switch 1 6 simultaneously with the pump 6. The second heating element may be switched on using the second set of contacts of the pressure switch 1 6.

It will be appreciated that the first and second predetermined pressure are adjustable having regard to the requirements of the installation.

Claims (1)

1. An apparatus for supplying instantaneous hot water for washing purposes which apparatus comprises an inlet for water from a water reservoir; an electrically operated pump for assisting the flow of the water through a chamber having a heating element adapted to heat the water as it passes therethrough; an outlet for the water; a first means responsive to a first predetermined pressure of water through the chamber for actuating the pump; and a second means responsive to a second predetermined pressure of water through the chamber for actuating the power supply to the heating element.

2. An apparatus as claimed in claim 1 wherein said first predetermined pressure is at least about 1 .38kPa.

3. An apparatus as claimed in claim 1 or claim 2 wherein said second predetermined pressure is at least about 48.25kPa.

4. An apparatus as claimed in any of claims 1-3 wherein the heating element has a rating of up to about 8.4kW.

5. An apparatus as claimed in any of claims 1-3 wherein the chamber has a pair of heating elements each having a rating of about 4.2kW.

6. An apparatus as claimed in claim 5 wherein said first means is adapted also to actuate the power supply to one of said heating elements and while the said second means actuates the power supply to the other of said two heating elements.

7. An apparatus as claimed in any of claims 1-6 wherein a valve for controlling the flow of water through the apparatus is located downstream of the pump and upstream of the chamber.

8. An apparatus as claimed in any of claims 1-7 wherein the outlet is connectable to a shower head.

10. An apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

11. Any novel feature or combination of features herein described.