GB2162027A - Electric water heater - Google Patents

Abstract

A heater (81) for use with an apparatus for supplying instantaneous hot water for washing purposes is provided. The heater has a chamber (81) having inlet (82) and outlet (83) ports for the water. In the chamber is housed an electric heating element (88) which is electrically isolated from the water and has a first end (86) which leads into a substantially helical portion (89). The helical portion generates a substantially tubular cavity and leads into a substantially circular portion (90) the diametric plane of which is transverse to the diametric plane of the cavity. The circular portion leads into a substantially straight portion (91) which passes through the cavity and is substantially parallel to the longitudinal axis of the cavity. The straight portion terminates a second end (87). The first and second ends are connectable to an electrical supply. <IMAGE>

Description

SPECIFICATION A heater for use with an apparatus for supplying instantaneous hot water for washing purposes This invention relates to a heaterfor use with an apparatus for supplying instantaneous hotwaterfor washing purposes.

In particular, it relates to a heater of the type comprising a passageway through which the water flows when the apparatus is in use, the water being heated by an electric element located in the said passageway.

Several heaters ofthe type referred to are known.

They essentially fall into two basic categories. In the first category of known heaters, the element is of the type which is electrically isolated from the water, the element serving to heat a metal sheath which in turn heats the water. In the second category of known heaters, the element is ofthe type which is not electrically isolated from the water. This invention is directed to a heater of the first category.

A significant problem of the known heaters of the first category is that a considerable volume of water must be heated having regardtothetypeand configuration of the heating element employed.

Furthermore, having regard to the relatively large volume of water being heated, considerable back pressure results leading to a poor water pressure at the outlet particularly when the water is fed from a reservoir in the building having the heater. It is an object of the present invention to overcome these problems.

The invention therefore provides a heater for use with an apparatus for supplying instantaneous hot water for washing purposes which heater comprises a chamber having an inlet portforthe water and an outlet portforthe water; chamber having an electric heating element which is electrically isolated from the water; the heating element comprising a first end which leads into a substantially helical portion and which helical portion generates a substantially tubular cavity; the helical portion leads into a substantially circular portion the diametric plane ofwhich is transverse to the diametric plane of the cavity; the circular portion leads into a substantially straight portion which passes through the cavity and is substantially parallel to the axis of the helical portion; and the straight portion terminates in a second end, said first and second ends being connectable to an electrical supplyforthe element.

Preferably, the inlet port is located near the circular portion. The advantage of this isthatwhen the water, which may be at a pressure as low as 1.38 kPa (0.2 psi), enters the chamber the circular portion provides a smooth barrierfortheflowofwaterand directs the water around the sides of helical portion. In addition, the circular portion directs the flow of water into the cavity.

Preferably, the heater, when in use, is mounted so that the inlet port is located atthe bottom of the chamber and the outlet portion is located at the top of the chamber. The advantage ofthis is that as the water is being heated, natural convection currents facilitate the flow ofwaterthrough and around the heating element.

Preferably, the heater is used in conjunction with an apparatus of the type described in the Specification of copending Irish PatentApplication No.1558/84.

The invention will be understood in greater detail from the following description of a preferred embodi mentthereofgiven by way of example only and with reference to the accompanying drawings in which: Figure 1 is an elevation and partly cut-away view of a heater according to the invention having first heating elementtherein; Figure 2 is a perspective view of a second heating elementfor use in the heater of Figure 1; and Figure 3 is a plan view of an apparatus for heating water having a heater according to the invention therein.

Referring nowto the drawings and in particular to Figures 1 and 2 thereof, there is shown a heater8 according to the invention.

The heater 8 comprises a chamber 81 having an inlet port 82 and an outlet port 83 for water. The bottom ofthe chamber 81 is closed by a leak-proof cap 84 while the top is closed bya leak-proofcap 85 having the terminals or ends 86,87 of a heating element 88 disposed in the chamber 81. The heating element 88 is of the type which is electrically isolated from the water by a metal sheath and wherein the end 86 leads into a helical portion 89 which leads into a substantially circular portion 90 which leads into a substantially straight portion 91 which terminates in the end 87.The diametric plane ofthe circular portion 90 is transverse to the diametric plane ofthehelical portion 89.The straight portion 91 is substantially parallel to the axis ofthe helical portion 89 and passes through the cavity generated bythe helical portion89.Thecircular portion 90 is disposed centrallyabovethe inlet82.

In Figu re 2 of the drawings is shown a second electric heating element 88a which may be disposed in the chamber 81 in place ofthe heating element 88. The second heating element 88a essentially comprises two heating elements 88b, 88cofthe same shape and configuration as the heating element 88 and in parallel relationship. Likethe heating element 88, the first heating element 88b has an end 86b, a helical portion 89b, a circular portion 90b, a straight portion 91 band an end 87b. Similarly, the second heating element 88c has an end 86c, a helical portion 89c, a circular portion 90c, a straight portion 91 cand an end 87c.The ends 86b, 86c, 87b and 87e are collectively referred to and shown in Figure3 ofthedrawings as electrical connectors 11.

Each of the heating elements 88b, 88c may operate together or independently as desired.

The chamber 81 has an internal diamater of at least 40mm preferably about 54mm and a length at least 100mm preferably about 174mm. Itwill,therefore, be appreciated that a relatively small volume of water is housed in the chamber 81 and having regard to the factthatthe heating element88a has a rating of unto 8.4kW the time taken to heat the water in the chamber 81 is considerably less when compared with known heaters ofthe first category hereinbefore referred to.

The heater 8 may be used in an apparatus of the type described in the Specification of co-pending Irish Patent Application No. 1558/84. Figure 3 ofthe drawings shows such an apparatus 1 which essentially comprises a water pipe 4which leads into an electrically operated pump 6 having a cooling fan 7.

The pump 6 is connected to the heater8 via a valve 9.

The heater8 is mounted on a base 2 by means of screws 2a. Attached to the water outlet 83 is a water outlet pipe 10 leading to a shower head (not shown).

The other components of Figure 3 viza thermostat 12, a relay 13, a terminal block 14, and a pressure switch 16 are described in the Specification of Irish Patent Application No.1558/84 referred to above. A switch 15 is also provided which will electrically disconnect one or both ofthe elements 88 or88b and 88c,as appropriatetoenablethe userto have a cold shower orto accommodate the intake of water at a relatively highertemperature due to seasonal variations.

To use the apparatus 1, the valve 9 is opened so that water flows passively into the heater 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 (0.2 psi) will activate a first set of contacts in the pressure switch 16 thereby triggering the pump 6to operate.As soon as the pump 6 operates, the pressure ofwaterflowing through the heater8will increase substantiallyto a level of about 48.26 kPa (7psi) where a second set of contacts are activated which operate the relay 13 to switch on the heating elementinthe heater8. Ifforanyreason, including shutting the valve 9, the pressure of water passing through the heater8falls below48.26 kPa the second set of contacts will again operate to shut offthe electrical supply to the heating element but the pump 6 will continue to operate. Thus, the element of the heater is cooled in a stream ofwaterwhich enables the residual heatofthe elementto be dissipated quickly and safely.As the water pressure falls furtherto 1.38 kPa the first set of contacts operate to switch offthe pump 6 until finally, the valve 9 is closed completely thereby stopping the flow ofwaterthrough the apparatus 1.

From the drawings, it will be appreciated that a very simple plumbing layout is possible. Furthermore, the layout provides for minimum resistance to the flow of water and thereforethe pump 6 can have a relatively low pumping pressure capacity and can be a drain pump of a well known type used in dishwashers or clothes washing machines.

Furthermore, in the apparatus 1, the valve 9 serves to initiate the flow ofwaterthrough the apparatus 1 whichflowtriggersthe 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 have been eliminated. In addition, the safety features which are desirable in such an apparatus are simple and effective.

Itwill be appreciated thatthe heater 8 may also be used as an in-line heaterforwaterwhich is not necessarily intended for use in a shower. Thus, the heater 8 could be attached to water supply just upstream of a tap of a sink or wash basin, the heating elements 88 or88b or88c, as the case may be, being activated byth a flow ofwaterthrough the chamber 81 using an appropriate electrical circuit incorporating a pressure sensitive switch. Considerable savings in electricity costs may be expected from the use of a heater according to the invention as it is only necessaryto heatwaterwhich is required for immediate use. Fu rthermore, the compact size of the heater according to the invention enables relatively easy installation just upstream of a water outlet such as a tap.

Claims (9)

1. A heaterfor use with an apparatusforsupplying instantaneous hotwaterforwashing purposes which heatercomprise a chamber having an inlet portforthe water and an outlet portforthe water; the chamber having an electric heating element which is electrically isolated from the water; the heating element comprising a first end which leads into a substantially helical portion and which helical portion generates a substan tiallytubularcavity; the helical portion leads into a substantially circular portion the diametric plane of which istransverse to the diametric plane ofthe cavity; the circular portion leads into a substantially straight portion which passes through the cavity and is substantially parallel to the longitudinal axis of the cavity; and the straight portion terminates in a second end, said first and second ends being connectable to an electrical supplyforthe element.

2. A heater as claimed in claim 2 which further comprises a second heating element in substantially parallel relationship with the first heating element, said first and second heating elements being operable independently of each other or in unison.

3. Aheaterasclaimed in claim 2wherein the inlet port is located near the circular portion(s).

4. Aheaterasclaimed inanyofclaims 1-3wherein the heater, when in use, is mounted so that the inlet port is located atthe bottom of the chamber and the outlet port is located near or at the top of the chamber.

5. A heateras claimed in any of claims 1-4wherein the internal diameterofthe chamber is atleast40mm and the length is at least 1 OOmm.

6. A heater as claimed in any of claims 1-5 wherein the internal diameter of the chamber is about 54mm and the length of the chamber is about 1 74mm.

7. A heater as claimed in any of claims 1-7 wherein the heating capacity of the or each heating element is about 4.2 kW.

8. A heater substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

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