GB2249615A - An electric heater for heating a flow of water or other liquid - Google Patents

Abstract

An electric water heater has an electrical heating resistor (R) arranged to heat water flowing through a heating chamber from an inlet (3) to an outlet (14). A partition wall (6) separates an electrical control circuit from the heating chamber. The control circuit (Ce, P, T) is arranged to regulate and supply power to the heating resistor (R) so that the water temperature may be controlled. The control circuit incorporates a triac (T) mounted to extend through the partition wall (6) and to protrude into the heating chamber. An aperture (9c) and a flow passage between a plate (13) and the wall (6) in the heating chamber directs incoming cold water onto the triac base such that the triac (T) is effectively cooled and the incoming water is pre-heated. <IMAGE>

Description

2 2 '+ 90 15 AN ELECTRIC HEATER FOR HEATING A FLOW OF WATER OR OTHER

LIQUID The present invention relates to an electric heater for heating a flow of water or other liquid. The heater may be used, for example, for heating water for a shower or other domestic purposes.

Water heaters for showers, baths, and water faucets generally may control the water temperature by at least one mechanical switch arranged to make and break an electric circuit so that power is either interrupted or supplied to an electrical resistor arranged to heat the water flowing through a heating chamber.

Such a conventional water heater has a number of inconveniences and problems which shorten the service life of the heater and may cause discomfort to a user trying to control the temperature of the heated water output.

One such inconvenience is that the conventional heater system allows only static adjustment of the water temperature, which may be, hot, warm or cold, there being no intermediate adjustment of the temperature of the water supplied. The fixed settings may be provided by manual actuation of a lever, step by step, to govern the hot warm or cold conditions.

An effort to eliminate such inconveniences was made by developing an electric water heater having continuous temperature regulation. Such an electric heater comprises an electrical heating resistor disposed within a chamber where the water is to be heated, and an electronic circuit, controlled by a potentiometer outside the device, to enable gradual and continuous adjustment of the voltage applied to the heating resistor and, consequently, continuous variation of the temperature gradient within the heating chamber.

In an electronic circuit for continuous adjustment of the temperature of water in the heating chamber, a dissipator plate is provided on the outside of the heating chamber, or on an electrical actuator chamber, and a triac is mounted on the dissipator plate. The triac is electrically connected across the terminals of the electrical heating resistor, across the movable contacts and fixed contacts mounted together with the electronic components and a potentiometer, and with these components provides the circuit for continuous temperature adjustment of the water flowing through the water chamber.

Although such a water heater does not have inconveniences associated with conventional heaters and shower baths, the positioning of the triac on the dissipator plate causes thermal energy generated by the heating of the triac to be lost, and also adds weight to the device itself because the dissipator plate has to be provided and usually takes up almost half of the area of a wall of the heating chamber, and also is of considerable thickness.

It is an object of the present invention to provide an electric heater for heating a flow of water or other liquid in which the problems and inconveniences discussed above are reduced.

According to the present invention there is provided an electric heater for heating a flow of water or other liquid comprising a liquid heating chamber through which liquid is arranged to flow, a controllable electrical heating element arranged in said heating chamber for heating the liquid flowing therethrough, and an electrical control circuit for controlling the electrical power supplied to said heating element, said liquid heating chamber being defined within an enclosure incorporating a partition wall and said electrical control circuit being disposed on the side of said partition wall outside of said liquid heating chamber, wherein said electrical control circuit comprises an electrical power switch which is mounted to protrude through said partition wall into said liquid heating chamber, and wherein a flow passage is defined within said liquid heating chamber and is arranged to direct liquid to be heated to said power switch.

As a dissipator plate, for example, is not required by an electric heater of the invention, the overall weight of the heater can be reduced as compared to known heaters.

A heater of the invention also has the advantage that power is not lost by the dissipation of heat generated by the power switch as this aids in warming the liquid flowing through the heater, and additionally cooling of the power switch also takes place.

In an arrangement of the invention the cooling of the power switch is actually achieved by the flow of cold water or other liquid into the chamber to be heated.

In an embodiment, said power switch is mounted on and extends through said partition wall, and wherein said flow passage communicates with an inlet for unheated liquid into said liquid heating chamber.

Preferably, said flow passage is defined by a plate mounted within said liquid heating chamber and extending substantially parallel to at least an adjacent part of said partition wall, and wherein an inlet pipe for unheated liquid has outlet holes therein arranged to direct jets of unheated liquid into said f low passage.

Alternatively, or additionally, said electrical power switch extends through an opening in said partition wall, and said flow passage is defined by said partition wall and a plate spaced f rom said partition wall, said plate being affixed to an end of said power switch protruding into said liquid heating chamber, and wherein an inlet pipe for unheated liquid has outlet holes therein arranged to direct jets of unheated liquid into said flow passage.

For example, the spacing between said plate and said partition wall is greater than the amount by which said power switch protrudes into said liquid heating chamber.

In an embodiment, said inlet pipe extends substantially axially within said liquid heating chamber. Preferably, said outlet holes are disposed in a portion of the inlet pipe adjacent or adjoining said partition wall, and are spaced radially and are aligned substantially circumferentially.

Preferably, said electrical power switch comprises a triac.

An embodiment of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 shows a front view of a water heater with continuous temperature adjustment, partially cutaway; Figure 2 shows an enlarged detail of the heater of Figure 1 showing the mounting of a triac; Figure 3 shows a front view of a partition wall of the heater of Figure 1; and Figure 4 shows a view of the heater of Figure 1 in a plane rotated 90' relative to the plane of Figure 1, and partially cutaway.

The figures illustrate a water heater of the present invention which is arranged to heat water flowing therethrough, for example, for providing temperature controlled hot water for a shower or the like. In the embodiment illustrated, the heater is installed such that the water flow therethrough is substantially horizontal.

The heater shown in the drawings comprises a generally tubular-shaped body 1 provided with a dished end wall 2 on which an externally threaded tubular projection 3 for entry of cold water is formed. An extreme edge of said tubular body 1 incorporates an orthogonal annular rim 4 provided with a plurality of holes 5 through which retaining bolts (not illustrated) are arranged to extend to affix said rim 4 to a circular plate 6 defining a partition or intermediate wall. This partition or intermediate wall 6 separates and seals the water heating chamber relative to an outer portion or dry chamber of the tubular body 1. The dry chamber is closed by a generally frustoconical dome 7 and houses the electrical and electronic components of an electrical control circuit providing temperature regulation.

The intermediate wall 6 isolating the heating chamber from the dry chamber or electrical or electronic circuit housing carries and positions an electrical resistor R which is electrically connected to terminals 8 which extend through the intermediate wall 6. Centrally thereof a rod enclosed in two coaxial tubes 9, 9a extends through the intermediate wall 6 substantially orthogonally thereto. The coaxial tubes 9, 9a are surrounded simultaneously by a return spring 9b having a rear end which bears against a circular part 10. The periphery 101 of the circular part 10 is flexible such that the circular part 10 forms a -6 plunger arranged, under the pressure of incoming water into the heating chamber, to move and displace the rod and part of the tube 9a axially rearwardly within the heating chamber.

The outer tube 9, which encloses tube 9a and the push rod of circular part 10, incorporates, midway between its upper peripheral surface, adjoining the intermediate wall 6, four holes 9c which are circumferentially aligned and radially spaced. The holes 9c face a point where a triac T or other power switch is installed or secured, so that the incoming flow of cold water is aimed directly at the base of the triac T, as illustrated in the figures.

The intermediate wall 6 is provided with an opening 11 in its lower surface through which the triac T extends. This triac T is electrically connected across terminals 8 of the electrical resistor R, across the movable contacts and fixed contacts mounted together with suitable electronic components Ce and with a potentiometer P, thus completing the components which form a continuous temperature regulator for the heater.

With the triac T extending through the intermediate wall 6, a sealing ring 12 is provided thereon, and a.small dividing plate 13 is disposed substantially parallel to and spaced from the intermediate wall 6. The wall 6 and dividing plate 13 define a flow passage for cold water flowing through the inlet 3 and inlet tube or pipe 9 and hence out of the holes 9c. The cold water in the flow passage is directed against ' the protruding base of the triac T. The dividing plate 13 is thus kept plunged in the portion of water in the heating chamber, separating the cold water that flows through holes 9c for improved cooling of the triac T.

The intermediate wall 6 further incorporates an orthogonally and forwardly extending hot-water outlet tube 14 which extends out of the frustoconical dome 7, and which covers and protects the electrical and electronic components from the front housing.

This dome 7 is perforated centrally to enable a shaft of the potentiometer P to extend therethrough, said shaft being provided with a manual actuator knob 15 on its free end outside the said dome 7.

It will be appreciated that with the base of the triac T in direct contact with the flow of cold water in the heating chamber, the heat given off by the triac is dissipated by this flow of cold water, causing heat to be exchanged between the triac T and the water, which improves heater efficiency and avoids loss of power.

This dissipation of the heat generated in the triac T is optimised by the dividing plate 13, which is preferably manufactured of heat-insulating material, as the said dividing plate 13 separates the water being heated from the cold water of the inlet which flows through the holes 9c. The cold water flowing around the triac T is thus unaffected by the water undergoing heating.

Although a preferred embodiment has been described and illustrated, it will be appreciated that variations and modifications to the invention may be made within the scope of the appended claims.

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Claims (16)

1. An electric heater for heating a flow of water or other liquid comprising a liquid heating chamber through which liquid is arranged to flow, a controllable electrical heating element arranged in said heating chamber for heating the liquid flowing therethrough, and an electrical control circuit for controlling the electrical power supplied to said heating element, said liquid heating chamber being defined within an enclosure incorporating a partition wall and said electrical control circuit being disposed on the side of said partition wall outside of said liquid heating chamber, wherein said electrical control circuit comprises an electrical power switch which is mounted to protrude through said partition wall into said liquid heating chamber, and wherein a flow passage is defined within said liquid heating chamber and is arranged to direct liquid to be heated to said power switch.

2. An electric heater as claimed in Claim 1, wherein said power switch is mounted on and extends through said partition wall, and wherein said flow passage communicates with an inlet for unheated liquid into said liquid heating chamber.

3. An electric heater as claimed in Claim 2, wherein said flow passage is defined by a plate mounted within said liquid heating chamber and extending substantially parallel to at least an adjacent part of said partition wall, and wherein an inlet pipe for unheated liquid has outlet holes therein arranged to direct jets of unheated liquid into said flow passage.

4. An electric heater as claimed in any preceding claim, wherein said electrical power switch extends through an opening in said partition wall, and said flow passage is -g- defined by said partition wall and a plate spaced from said partition wall, said plate being affixed to an end of said power switch protruding into said liquid heating chamber, and wherein an inlet pipe for unheated liquid has outlet holes therein arranged to direct jets of unheated liquid into said flow passage.

5. An electric heater as claimed in Claim 4, wherein the spacing between said plate and said partition wall is greater than the amount by which said power switch protrudes into said liquid heating chamber.

6. An electric heater as claimed in any of Claims 3 to 5, wherein said inlet pipe extends substantially axially within said liquid heating chamber.

7. An electric heater as claimed in any of Claims 3 to 6, wherein said outlet holes are disposed in a portion of the inlet pipe adjacent or adjoining said partition wall, and are spaced radially and are aligned substantially circumferentially.

8. An electric heater as claimed in any preceding claim, wherein said electrical power switch comprises a triac.

9. An electric heater as claimed in any preceding claim, wherein said controllable electrical heater element comprises a heating resistor.

10. An electric heater as claimed in any preceding claim, for heating water, and having an inlet pipe for flowing cold water into said chamber, and an outlet pipe through which heated water is to be discharged, said heater element being mounted in said heating chamber adjacent an end of said outlet pipe.

11. An electric heater for heating a flow of water or other liquid substantially as hereinbefore described with reference to the accompanying drawings.

12. An arrangement for a triac in shower baths or throughgoing heaters, of the type comprised of an electrical heating resistor, disposed within the chamber where the water is heated, said electrical heating resistor being wired to an electrical and electronic energizing circuit disposed in the device's dry chamber, kept separate from the water chamber by a bottom or intermediate wall whereon the triac is mounted, which triac continually regulates the power supplied to the electrical heating resistor, characterised in that the triac is mounted by running directly through the said intermediate wall, with its electrical connecting terminals facing the device's dry chamber and with its base or bottom wall running through the intermediate plate or wall and carrying a small dividing plate held parallel to the intermediate plate and plunged in the portion of cold water coming from outlet holes provided on the cold water inlet tube, aiming the jets of cold water directly at the triac.

13. An arrangement for a triac in shower baths or throughgoing heaters, according to Claim 12, characterised in that the triac runs through an opening provided on the lower portion of the intermediate wall, with a small dividing plate being affixed to its base, whereby the cold water in the heating chamber, coming from the holes, is directed permanently to the base of the triac.

14. An arrangement for a triac in shower baths or throughgoing heaters, according to Claim 12, characterised in that a distance is provided between the dividing plate and intermediate wall, which distance is slightly greater than the portion of the triac plunged in the heating chamber.

15. An arrangement for a triac in shower baths or throughgoing heaters, according to any of the previous Claims 12 to 14, characterised in that the heat generated by the triac is dissipated and transferred to the coldwater flow issuing from the holes in the water inlet tube located axially within the heating chamber.

16. An arrangement for a triac in shower baths or throughgoing heaters, according to Claim 15, characterised in that the cold-water flow inlet holes are radially disposed on a peripheral portion of tube adjoining the intermediate wall, with these holes being aligned aside one another and facing the base of the triac.