GB1586481A - Water heaters or boilers - Google Patents

Description

(54) IMPROVEMENTS IN AND RELATING TO WATER HEATERS OR BOILERS (71) We, W.M. STILL & SONS LI MITED, a British Company of Fellows Road, Hastings, East Sussex, TN34 3TX, 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 water heaters or boilers of the type operating under atmospheric pressure wherein steam is produced and is particularly but not exclusively concerned with boilers of the type known as "expansion boilers" in which during use, water is heated to boiling temperature.

Expansion boilers of the type to which this invention relates comprises a water container or vessel, connected to a cold water supply tank or cistern, and heated either by electricity or by any other means e.g. gas or steam, a tray, trough or the like being located within the container in the upper region thereof with the side and/or end walls of the tray or trough extending above the predetermined normal water level in the vessel. A draw-off tap communicates with the tray or trough. When the draw-off tap is opened to discharge water from the tray or trough and hence from the boiler, additional heat is automatically supplied to heat the water in the vessel causing it to expand and the level to rise in the vessel until it overflow the top edges of the walls of the tray or trough which act in effect as a 'weir'. This acts to keep the tray or trough full of boiling water.Cold water is fed into the vessel from a supply tank, cistern or the like to replace that discharged from the boiler. When the drawn-off tap is closed the heat supplied to the vessel is autpmatically reduced but remains sufficient to maintain the water in the tray/trough at a predetermined temperature. Such a boiler will hereafter be referred to as "an expansion boiler of the type described".

An expansion boiler of this type provides water at a suitable temperature for hot beverages such as tea, coffee and the like and at atmospheric pressure.

When the boiler is in use, water in the container is heated to boiling point immediately prior to discharge or is stored at a suitable predetermined temperature which is relatively high so that the water can rapidly be brought to boiling point when water is drawn off. During both conditions, steam is generated which is discharged into the atmosphere.

This steam tends to condense on the ceiling or on other surfaces of the room in which the boiler is situated, or in the atmosphere of the room tending to result in a damp environment. Also this discharge causes a continuous loss of energy.

A boiler in accordance with this invention has the space in its heated water container or vessel above the predetermined water level, connected to a condensing chamber position within a cold water supply tank or cistern. This condensing chamber is preferably open to atmosphere and has a condensate discharge outlet.

In use, steam which is generate in the water container or vessel both during drawoff of boiling water and during normal heating of the water stored in the container, condenses in the condensing chamber in the cold water supply tank or cistern and thus gives off heat to the water in that tank, which heat is usefully used as and when water from the 'cold' water tank is used to make-up water drawn-off from the main boiler vessel. This also has the advantage of preventing steam from being discharged into the atmosphere.

Preferably the main water container/boiler vessel and the cold water supply tank are located in an outer casing which is ventilated to allow adequate air flow through the casing around the component parts of the boiler.

The boilder is preferably "an expansion boiler of the type described" and the heated water container or vessel preferably has an inner chamber positioned centrally within the main vessel, the top edge of the inner chamber being positioned just above the normal water level and constituting the 'weir' edges. Hence, when water is heated by a heating element located in the inner chamber, it expands and flows over the edge into a collecting trough positioned around the inner chamber and spaced from the wall of the main vessel. The draw-off tap communicates with this trough.

Whilst the water may be heated by any convenient heating element, it is preferred to use an electrical heating element which extends down into the open top of the inner heating chamber. This heating element, when the appliance is in an idle or storage condition, acts to keep the water hot enough to enable the appliance rapidly to supply boiling water on demand. When the drawoff tap is opened this preferably operates a switch fully to energize the heating element rapidly to produce boiling water.

The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawing which illustrates a preferred embodiment of expansion boiler of the type described in accordance with the invention.

The boiler comprises a rectangular main water container or vessel 2 connected to a rectangular cold water supply tank or cistern 4 by means of a water pipe 6 connecting the bottom portions of the water container and the supply tank. The tank 4 is positioned alongside the water container.

The main water container has an inner heater chamber8 open at its top and bottom surfaces and into which an electrical heating element 10 extends. The top edge 12 of this inner heater chamber is positioned just above the normal water level 14, and a trough 16 extends around the outer surface of the inner heater chamber with the outer wall 18 of the trough spaced from the outer wall of the main water container. Consequently when water is heated on full energization of the electrical heating element 10, the water within the inner chamber 8 expands and flows over the 'weir' edge 12 into the trough 16 from which it may be drawn off through an outlet 20 controlled by a draw-off cock diagrammatically illustrated at 22. This cock 22 is connected to a switch for the heating element 10 so that the heating element is fully energized when the cock is open.Thus on opening of the cock, water within the inner chamber is brought rapidly to boiling point, expands, flows into the trough 16 and is discharged through the cock 22.

As water is discharged from the main boiler vessel, water from the cold water tank or cistern 4 enters the bottom of the main heater vessel through the pipe 6 to make-up for the water discharged.

When the cock 22 is closed, the energy input to the heater element 10 is reduced so that the temperature of the water within the inner heated chamber is maintained only at a suitable storage temperature of about 208"F by means of a thermostate (not shown). The level of the water in the heater vessel, which is also that 14 within the water cistern is maintained by operation of a ball cock generally indicated at 24 within the cold water cistern which acts to control flow bf fresh cold water into the cistern through a pipe 26.

The top of the main water container or vessel is closed by a lid 28 and the space generally indicated at 30 within the vessel, above the water level 14, is connected to a condensing chamber 32 located within the cold water cistern by means of a pipe 34.

The condensing chamber 32 is connected to atmosphere through a pipe 36 extending up, out from the water cistern and to a condensate discharge pipe 38.

In use, steam generated in the main water container both during draw-off, when the heater 10 is energized to its maximum extent and during the storage period, when the heater 10 is energized to a lesser extent, passes into the space 30. From there the steam flows through the pipe 34 into the condensing chamber 32 within the cold water tank, where the steam condenses giving up its heat to the water within the cistern 4. This heat is, in effect, partially 'stored' by the water in the water cistern and is used as and when water from this cistern passes into the main water vessel to "makeup" for water drawn therefrom.

It will be appreciated that the boiler or main water vessel 2 operates at atmospheric pressure due to the fact that the space 30 above the water level is connected to atmosphere through the pipe 34, condensing chamber and pipe 36.

As steam is prevented from discharge to the atmosphere, a boiler in accordance with the invention avoids the problem of steam condensing on surfaces adjacent the boiler or in the atmosphere surrounding the boiler.

The component parts of the boiler described above are enclosed within an outer casing generally indicated at 40 which casing is such as to allow adequate air flow through the appliance.

The main heating element can either be on all the time to maintain the temperature for storage, governed, for example, by a thermostat or a separate pilot heating element could be employed to produce heat during the storage period.

Equally, both the main and pilot elements can work together (for initial quick heatup).

If the pilot element is an electric element it may be positioned adjacent the heater 10.

If gas is used as the heating medium, the pilot heater is positioned beneath the heating chamber.

WHAT WE CLAIM IS: 1. A boiler wherein the space in its heated water container or vessel, above the predetermined water level, is connected to a condensing chamber positioned within a cold water supply tank or cistern.

2. A boiler as claimed in accordance with Claim 1 in which the condensing chamber is open to atmosphere thus enabling the boiler to operate at atmospheric pressure.

3. A boiler as claimed in Claim 1 or 2 which is an expansion boiler of the type described.

4. A boiler as claimed in Claim 2 wherein the heated water in the water container/ vessel comprises a heater chamber positioned within the main body of the vessel having an open top and bottom and containing a heating element, the top edge of the inner chamber being positioned just above the predetermined water level and constituting the 'weir' edge over which the water flows when expansion takes place due to heating, and a trough to receive water flowing over the said 'weir' edge, the trough surrounding the inner heater chamber and being spaced from the outside wall of the vessel, the trough being connected to an outlet through a draw-off clock.

5. A boiler as claimed in any one of the preceding claims wherein the cold water make-up cistern is positioned alongside the main water container or vessel, the water level in the water cistern and hence in the main water container being controlled by a ball cock device positioned within the water cistern.

6. A boiler as claimed in any one of the preceding claims wherein the main water vessel and cold water or make-up cistern are positioned within an outer case which is ventilated to allow air to flow through the appliance around the component parts thereof.

7. A boiler as claimed in any of the preceding claims wherein the heating element is electrically powered.

8. A boiler as claimed in any of the preceding claims in which the heater from the main water container is energized to its maximum extent as a result of the opening of a water draw-off cock.

9. An expansion boiler substantially as hereinbefore described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. Equally, both the main and pilot elements can work together (for initial quick heatup). If the pilot element is an electric element it may be positioned adjacent the heater 10. If gas is used as the heating medium, the pilot heater is positioned beneath the heating chamber. WHAT WE CLAIM IS:

1. A boiler wherein the space in its heated water container or vessel, above the predetermined water level, is connected to a condensing chamber positioned within a cold water supply tank or cistern.

2. A boiler as claimed in accordance with Claim 1 in which the condensing chamber is open to atmosphere thus enabling the boiler to operate at atmospheric pressure.

3. A boiler as claimed in Claim 1 or 2 which is an expansion boiler of the type described.

4. A boiler as claimed in Claim 2 wherein the heated water in the water container/ vessel comprises a heater chamber positioned within the main body of the vessel having an open top and bottom and containing a heating element, the top edge of the inner chamber being positioned just above the predetermined water level and constituting the 'weir' edge over which the water flows when expansion takes place due to heating, and a trough to receive water flowing over the said 'weir' edge, the trough surrounding the inner heater chamber and being spaced from the outside wall of the vessel, the trough being connected to an outlet through a draw-off clock.

5. A boiler as claimed in any one of the preceding claims wherein the cold water make-up cistern is positioned alongside the main water container or vessel, the water level in the water cistern and hence in the main water container being controlled by a ball cock device positioned within the water cistern.

6. A boiler as claimed in any one of the preceding claims wherein the main water vessel and cold water or make-up cistern are positioned within an outer case which is ventilated to allow air to flow through the appliance around the component parts thereof.

7. A boiler as claimed in any of the preceding claims wherein the heating element is electrically powered.

8. A boiler as claimed in any of the preceding claims in which the heater from the main water container is energized to its maximum extent as a result of the opening of a water draw-off cock.

9. An expansion boiler substantially as hereinbefore described with reference to the accompanying drawing.