NZ238923A - Hot water heater: thermostats responsive to steam vented to make-up tank - Google Patents

Description

NEW ZEALAND PATENTS ACT. 1953 No.: 238923 Date: 11 July 1991 COMPLETE SPECIFICATION "Improvements in or Relating to Apparatus for Providing Hot Water" WE, ARDRICH AUSTRALASIA LIMITED a company duly incorporated under the laws of New Zealand of Unit 5, 31 Hannigan Drive, Auckland, New Zealand, 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:- ?"* ft 9 ? 3 V-/ W ^ The present invention relates to improvements in and/or relating to apparatus of a type for providing hot water such as might be required for tea or coffee making purposes.

Many forms of hot water producing apparatus are known. Many of these use electrical immersion elements in a tank from which hot water can be dispensed. Some incorporate a direct mains water feed to provide make-up water while others provide a make-up tank into which the mains or other water (hereafter "mains water") can be fed as demanded to make up the quantity being drawn from the make-up tank into the hot water chamber. Examples of such apparatus include those disclosed in New Zealand patent specification nos. 91180 and 195541.

There is a requirement whereby in addition to a thermostatic control of the energising of the heating of the hot water tank that there additionally be a backup which will deactivate the immersion or other usually electrical element in the event of the primary thermostat which controls temperature in the hot water chamber failing.

The present invention is directed to apparatus and/or a means of providing such safety features having an enhanced reactive capability or which will at least provide the public with a useful choice.

Accordingly in a first aspect the present invention consists in a hot water heater having (1) means defining in use a main water chamber including (i) an electrically powered water heater element (ii) a valved water outlet and (iii) a steam off take, and (2) a make-up chamber to contain water at the same level as the water level in the main chamber, said make-up chamber including (i) a water level controlled valved inlet for inflow water corresponding to any water in use drawn from said valved outlet of the main chamber, (ii) passageway defining means into said main chamber to enable a gravity feed of make-up water in use from the make-up chamber to the main chamber, such make-up water corresponding to any water taken from the main chamber via the valved outlet, (iii) thermostat means to control the activation of said electrically powered water heater element, and (iv) temperature activated means, to be directly or indirectly heated by stea^^ generated in said main water chamber as a backup for said thermostat means, capable of cutting electrical current to said electrically powered water heater element, the construction and arrangement of the apparatus being such that (A) said steam off take from said main chamber is to said thermostat means in said make-up chamber, (B) said temperature activated means is an over temperature non-self reset thermostat activated at a temperature above that which it experiences when said thermostat means in normal operation would normally deactivate said electrically powered water heater element, the activation of said temperature activated means not being dependent on steam venting from said main water chamber or said make-up chamber to atmosphere, and (C) said thermostat means is cooled by the presence of inflow water from said water level controlled valved inlet above the water level in said make up chamber.

Preferably said water level controlled valved inlet is a ball valved inlet.

Preferably activation of the temperature activated means is dependent at least in part on the temperature of steam above the water level in the make-up chamber.

Preferably said steam take off from said main chamber is via a conduit which ducts to and/or about part of said thermostat means.

Preferably said thermostat means is positioned above the water level in said make-up chamber.

Preferably said inflow water inflowing via said water level controlled valved inlet cascades substantially over said thermostat means in use.

One preferred form of the present invention will now be described with reference to the accompanying drawings in which; Figure 1 is a diagrammatic view showing apparatus in accordance with the present invention.

Figure 2 shows a preferred control circuit, and Figure 3 shows an exploded form of the preferred hot water dispensing apparatus.

The full disclosure of the patent specifications previously referred to are herein incorporated by way of reference.

In the preferred form of the present invention there is provided (preferably of a conductive material) means defining a main water containing chamber 1 which includes therewithin and preferably at a position not distant from the valved outlet for water therefrom an electrical immersion element 2. The valved outlet for water from the main chamber 1 is a tap arrangement 3.

The water level in the main tank 1 (which is sealed when tap 3 is closed except for its communication to and from a make-up chamber 4) is at that level indicated as 5 which preferably is substantially the same water level within the make-up chamber 4.

The level of the make-up chamber 4 is controlled by a ball valve 6 on a conduit 7 connected preferably to mains water but which ducts water into a zone above the water level 5 in the make-up chamber 4 where it impinges on or preferably cascades over the thermostat means Tl.

Preferably there is provided an off take steam conduit 8 from above the water level 5 in the main chamber 1 such that steam generated by the hot water therein passes through to the thermostat means Tl such that when the water in the main chamber is preferably at boiling the steam temperature is such as to deactivate the immersion element 2 by an appropriate actuation of the thermostat means Tl. The arrangement however that there be a direct in feed of the cold mains water via the valved conduit 7 directly to the thermostat means Tl means that the greatest possible temperature difference is capable of being sensed more immediately by the thermostat than would be the case if the in feed water first required admixture with water contained within the make-up tank 4 and for that then to have some influence on an environment about the thermostat means Tl.

In use an amount of water (say X) is drawn from the outlet tap 3 from the main chamber 1 and a corresponding amount of make-up water (X) flows from the make-up tank 4 down into tank 1 via the make-up conduit 9. The inflow via conduit 7 is also X.

A backup over temperature non-self reset thermostat T2 is preferably provided above the water level 5 in the make-up tank 4 such that the steam environment issuing from tank 1 via conduit 8 influences both Tl and T2 and is such that upon a failure of thermostat means Tl the pressure and/or temperature of the steam build up on excessive heating of the water in tank 1 trips T2 to cause a deactivation of the electrical supply to the immersion electrical element 2.

A person skilled in the art will appreciate the form that the non-self reset thermostat control over temperature conditions T2 should possess unlike the characteristics of the thermostat means Tl. 9 s ft Q 9 1 Any appropriate configuration of the main chambers 1 and 4 can be used but ideally with the association of the two together such that there is on standing the prospect of some warming up of the water within the make-up chamber 4 and of course the capability of the two chambers to have a substantially common water level 5.

Figure 3 shows an exploded view of a preferred structural arrangement. It includes an overflow pipe 10.

It is believed that arrangement providing the immediacy of the activation of the immersion electrical element while also providing for the redundancy of one of two thermally activated means (directly or indirectly) to meet safety standards provides a worthwhile advance over previous automatic boiling water dispenser apparatus or the like. 238 923

Claims (8)

WHAT WE CLAIM IS: Q

1. A hot water heater having

(1) means defining in use a main water chamber including

(i) an electrically powered water heater element

(ii) a valved water outlet and

(iii) a steam off take, and

(2) a make-up chamber to contain water at the same level as the water level in the main chamber, said make-up chamber including

(i) a water level controlled valved inlet for inflow water corresponding to any water in use drawn from said valved outlet of the main chamber,

(ii) passageway defining means into said main chamber to enable a gravity feed of make-up water in use from the make-up chamber to the main chamber, such make-up water corresponding to any water taken from the main chamber via the valved outlet,

(iii) thermostat means to control the activation of said electrically powered water heater element, and

(iv) temperature activated means, to be directly or indirectly heated by steam generated in said main water chamber as a backup for said thermostat means,

capable of cutting electrical current to said electrically powered water heater element,

the construction and arrangement of the apparatus being such that

(A) said steam off take from said main chamber is to said thermostat means in said make-up chamber,

(B) said temperature activated means is an over temperature non-self reset thermostat activated at a temperature above that which it experiences when said thermostat means in normal operation would normally deactivate said electrically powered water heater element, the activation of said temperature activated means not being dependent on steam venting from said main water chamber or said make-up chamber to atmosphere, and

(C) said thermostat means is cooled by the presence of inflow water from said water level controlled valved inlet above the water level in said make up chamber.

2. Apparatus of Claim 1 wherein said water level controlled valved inlet is a ball valved inlet.

238923ture activated means is dependent at least in part on the temperature of steam above the water level in the make-up chamber.

4. Apparatus of any one of the preceding claims wherein said steam take off from said main chamber is via a conduit which ducts to and/or about part of said thermostat means.

5. Apparatus of any one of the preceding claims wherein said thermostat means is positioned above the water level in said make-up chamber.

6. Apparatus of any one of the preceding claims wherein said inflow water inflowing via said water level controlled valved inlet cascades substantially over said thermostat means in use.

7. Apparatus of any one of the preceding claims wherein the electrical circuitry of the apparatus is substantially as hereinbefore described with reference to the accompanying drawings.

8. Apparatus substantially as hereinbefore described with reference to the accompanying drawings.