GB2261937A - Water boilers - Google Patents

Abstract

A water boiler comprises a tank 12 with a heater 16 therein in order to heat the water. A supply line to the tank is provided with a throttling aperture 61 to ensure that the rate of feed of make-up water to replace water drawn off from the tank is at a rate to prevent rapid draw-off of hot water leading to delivery from the boiler of water which is under the desired temperature. The size of aperture 61 is matched to the heating capacity of the heater 16. Another heater 48 is activated when steam is required to produce a temporary pressurised steam space. A steam injection pipe 50 is removable. <IMAGE>

Description

Water Boilers This invention relates to water boilers, being apparatus for the provision of boiling water which can be dispensed selectively from a water outlet for any suitable use, such as for the making of hot beverages for example tea or coffee, heating edible fluent materials or for any other purpose as dictated by the user.

Water boilers for the production of water for making hot beverages are well known, and comprise essentially a tank for containing a body of water, and heating means for heating that water.

The water in the tank is heated by the heating means so as to be maintained as far as possible at a predetermined temperature, in the order of 1000C when the water is to be used for making tea. As will be understood, water may be drawn off from the tank at different rates depending upon the demand, and each boiler having regard to its volume and rating of the heating means has a maximum rate of draw off.

If that rate is exceeded, the water in the tank, being progressively replaced by cold water from a cold water inlet, reduces in temperature, when the boiler cannot be used further for a period to enable the temperature of water again to be raised to the predetermined value.

The water preferably flows from the tank under gravity and usually the water is maintained at a predetermined level inside the tank. Supplying cold water to the boiler tank to maintain said pre-determined level whilst dispensing is taking place does have the effect causing the water in the tank to cool down to a level below the predetermined temperature.

The present invention seeks to provide a water boiler wherein an improved performance may be obtained.

According to the present invention, a water boiler comprises a water tank, heating means for heating the water to a predetermined temperature, a water inlet and a water outlet, wherein the water inlet is throttled to restrict the inflow of cold water so that when the water is being drawn off the boiler at greater than a predetermined rate, the level of the water in the tank will fall due to the throttling of the water inflow.

The extent of throttling preferably is related to the rating of the heating means so that the inflow is restricted to a unit volume per unit time which is substantially equal to the rate at which the heating means can heat the inflowing water. For example, if the inflow is restricted to one pint per minute, the heating means will be such as to heat cold water to the predetermined temperature at a rate of one pint per minute. Typically such a heating means may be a 3Rw electric heater.

The throttling may be achieved by providing that the inflow is through a pipe in a supply tank, said supply pipe having a hole in the wall thereof through which the water flows, and which projects above the controlled water level in said supply tank so that in fact the inflow water is supplied at a constant head.

There are also known steam dispensing vessels which comprise pressure vessels in the nature of steam boilers having an outlet spout controlled by a valve for the dispensing of steam which is used for heating edible fluent materials and liquids, such as soups, sauces, puddings, and milk and beverages of other types. These pressure vessels are of course potentially dangerous, and therefore there are stringent regulations covering the installation and use of same.

The present invention in a preferred form provides that the boiler can provide for the issuance of steam, and in a preferred case the apparatus operates under conditions which in effect make it non-pressurized and therefore the regulations concerning pressure vessels should not apply thereto to the same extent.

In the preferred construction, said heating means comprises the first heating means for heating the body of water, the boiler further including a sub-chamber which contains some of the water of the body of water or is in hydraulic communication therewith, so that such water in the subchamber will essentially be at the same temperature as the body of water, a second heating means for heating such water in the sub-chamber above the predetermined temperature of the body of water (which is in the region of boiling point) so that such water in the sub-chamber can be made readily to give off steam which fills and/or creates a head space in the sub-chmaber, such head space being substantially closed except for a steam dispensing outlet through which steam can issue, said steam dispensing outlet being such as to be locatable in fluent material contained in a vessel for the steam heating of such fluent material, and operating means for the selective dispensing of water and steam from the water outlet and steam dispensing outlet.

The second heating means may be in the sub-chamber, and operable selectively by the operator of the equipment. When such second heating means is operated, the control system of the apparatus may arrange for the first heating means of the body of water to be switched off.

The bottom of the sub-chamber is preferably open and in free communication with the body of water in the tank. The said steam dispensing outlet may be adjustable so as to be swingable between an in-use and out-of-use position which facilitates placing the nozzle in a heating vessel and removing it therefrom. Also, it may be removable for repair and cleaning.

The apparatus may have a control system comprising temperature probes electronically sensing the temperature of the body of water at two levels e.g. a high level and a low level in order thermostatically to control the operation of the boiler for high demand and low demand, and in order to give an indication when the apparatus is ready for producing steam on demand.

The apparatus may be coupled to the mains through a suitable break tank and water reservoir, thereby preventing the flow of hot water back to the mains.

The boiler will be provided with suitable insulation as appropriate.

The first heating means and the second or sub chamber heating means may be any suitable, such as an electric heating coil.

The apparatus will preferably be constructed of metal components, with suitable thermal insulating jackets and padding, but it is to be understood that the invention is not necessarily to be limited to the use of metallic materials.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawing of which: Fig. 1 is a diagrammatic sectional elevation of an apparatus according to the invention; and Fig. 2 is a diagrammatic sectional plan showing the disposition of main chamber and sub chamber.

Referring to the drawing, the apparatus shown in Fig. 1 has an outer casing 10, and inside the apparatus is a water tank 12 which is preferably suitably thermally insulated, and which contains a body of water 14, which in operation will be maintained at substantially boiling conditions by means of an electric heating element 16. The top of the tank 12 has a lid 18 that is open to atmosphere through a vent 20.

The tank 12 furthermore has an outlet spout 22 through which, by control of the valve 24, boiling water can be drawn off.

The valve 24 is typically manually operable.

The tank 12 is supplied with cold water from a cold water mains inlet 26 which is connected to a float controlled valve 28 contained in a water tank 30 which limits the level of water in tank 30 to a predetermined value and forms an air break in the supply system, preventing the flow of water back to the water supply pipe 26. The tank 30 has an overflow 32, and an outlet pipe 34 therefrom leads to a water reservoir 36. The pipe 34 has a vent hole 38 to permit the reservoir 36 to become completely filled with water. A feed pipe 40 leads from the base of reservoir 36 to a point towards the bottom of the tank 12. The pipe 34 projects above the level in tank 30 and has a throttling hole 61 in the pipe wall to permit water to flow from tank 30 to reservoir 36.

Located inside the tank 12 is a sub-chamber 42 and the subchamber 42 is open at the bottom end and closed by means of a removable cap 44 at the top end. The quantity of water 46 in the sub-chamber 42 can be heated by means of a "steamer" heating element 48.

The purpose of the sub-chamber 42 is to provide a steam supply to a steam injection pipe 50, and to this end the only outlet from the top of the sub-chamber 42 is indeed the outlet pipe 50. The sub-chamber has, above the heating element 48 an outlet aperture 52, the purpose of which is to allow steam to escape and to prevent the heater element 48 from becoming exposed if the pressure in the head space in sub-chamber 42 for any reason exceeds a predetermined value.

This may occur for example when the steam from the outlet is injected to a thick fluid such as soup or rice pudding. In use, the nozzle 54 will typically be located in a jug or other vessel 56 containing a quantity of liquid or fluid 58 which has to be steam heated. The nozzle 54 may be designed so as to provide effective distribution of steam throughout the liquid 58. For example the nozzle may be defined by providing four slits 60 in the end of the pipe 50, and by closing the end of the pipe by means of a washer of which the end diameter is smaller than the internal diameter pipe 50.

Pipe 50 has a knob 51 by which it may be rotated from the vertical in-use position to a horizontal out-of-use position, and back again at will. The pipe 50 may furthermore be removed from the boiler at coupling 69 by being pulled outwards, for repair and cleaning.

Finally, a baffle 62 which is a perforated plate is provided at the top of the sub-chamber 42, but under the inlet end of the pipe 50.

As shown in Fig. 2, the tank 12 is in fact of square section, and the sub-chamber 42 is defined partly by a corner of the wall of tank 12 and by a right angled plate 43. This facilitates manufacturing of the apparatus, and enables the connections to the coil 48 and dispensing tube 50 to be directly through the wall of tank 12 which also facilitates construction. Any suitable shape of tank may however be adapted.

Operation of the apparatus is fundamentally simple. The element 16 keeps the water 14 in substantially boiling condition, and the control thermostats for the water 14 may be arranged so that the unit is set for economy running or high demand running. When it is required to produce steam from the nozzle 60, and when the apparatus indicates ready, the element 48 is activated (and this may if required cause automatic termination of operation of element 16) for example by turning a key or by depressing a spring loaded switch, these activities being in parallel circuits, and the body of water 46 in the sub chamber, which is relatively small in volume compared to the body of water 14, is rapidly heated and steam is given off from the surface thereof.Steam collects in the top of the sub-chamber 42, and commences generation of a pressure therein which causes downwards displacement of the water level 66 in the sub-chamber, and elevation of the water level 68 in the tank 12. The baffle 62 hinders progress of water droplets into the pipe 50, and this effect is enhanced by taking the top of pipe 50 to a position as close to the underside of cap 44 as possible, because then there is a centrifugal separation effect of water droplets and steam, preventing the water droplets from entering pipe 50. The dimensions of the sub-chamber and main tank are arranged so that the steam arriving at the top of the chamber 42 will be substantially dry or at least moisture droplet free, so that there will be no carry over of water (as opposed to steam) directly into the vessel 56.

Experiments have been carried out with a unit basically as illustrated, and extremely encouraging results have been achieved. Thus, steam for the heating of liquids arrives at the outlet nozzle 60 some 4 to 6 seconds after activating the element 48. The system is not essentially a pressurized system, because upon termination of the operation of the heating element 48, the top chamber 42 returns to atmospheric pressure, and the levels 66 and 68 again coincide.

The apparatus illustrated has particular advantage when functional to dispense hot water. To achieve this dispensing, valve 24 is opened and the water flows out under gravity. Assuming that the tank is full when dispensing starts and that all of the water is at the predetermined temperature for dispensing, water can be drawn off at a high rate and the level of water in tank 12 falls because the water is not made up at the same rate due to the throttling of the inflow by the hole 61, so that undesired cooling of the tank water cannot take place.

All water dispensed therefore is at the predetermined temperature until, if the high rate of dispensing continues, the water level in tank 12 falls to the water outlet, but even when this level is reached dispensing of the water at the predtermined temperature can continue at the rate at which water flows through hole 61 if the heating means 16 is, as it will be, capable of heating cold water to the predetermined temperature at the same rate as the cold water flows into the tank 12. Should dispensing cease before the level of the outlet valve 24 is reached, again the water flows into the tank at the same rate controlled by hole 61, and this inflowing water is heated at the same rate by heating means 16 so that the water in the tank 12 will always be at the predetermined temperature. Optimum dispensing of hot water is achieved.

The invention extends to boilers with or without the steam generator means.

The rating of the heating means 16 will be related to the desired inflow rate of water through aperture 61. The higher the heater rating, the higher the inflow rate which can be provided, improving the response times of the boiler.

By the arrangement described, it is not possible to discharge water from the tank 12 at other than the correct temperature; as the water in the tank never drops below the predetermined level the steam side of the apparatus functions effectively at all times which is a particularly important advantage.

At all times, the water in the tank 12 can be maintained at the correct operating temperature.

By having the heating element 48 in the lower end of subchamber 42, any scaling which occurs on the element 48, resulting in the dropping of scale material, will not result in clogging of the bottom end of the sub chamber 42, as such scale material will fall to the bottom of tank 12.

As indicated herein, the element 16 may be thermostatically controlled by electronic temperature sensitive probes detecting the temperature of the top of the water in tank 12 for economy running, and detecting the temperature of the bottom of the tank 12 for high demand running.

Although the head space above level 66 is substantially closed, it may be described to have an anti-vacuum passage leading into the headspace from above the level 68 and from atmosphere to prevent liquid from siphoning back from the vessel 56 to the headspace above level 66. This anti-vacuum passage should be sufficiently small to prevent excessive escape of steam during normal operation conditions of the apparatus.

Claims (11)

1. A water boiler comprising a water tank, heating means for heating the water to a predetermined temperature, a water inlet and a water outlet, wherein the water inlet is throttled to restrict the inflow of cold water so that when the water is being drawn off the boiler at greater than a predetermined rate, the level of water in the tank will fall due to the throttling of the water inflow, and wherein said throttling is achieved by providing an aperture in a supply pipe connecting the water inlet and water tank.

2. A water boiler according to claim 1, wherein the said supply pipe extends through a supply tank, and the supply pipe projects above the controlled water levels in the supply tank, the said aperture being in that part of the supply pipe which is in the supply tank so that in fact the water inflow is supplied at a constant head.

3. A water boiler according to claim 1 or 2, wherein the boiler provides also for the issuance of steam, and it is adapted to operate under conditions which make it nonpressurised.

4. A water boiler according to claim 3 wherein said heating means comprises the first heating means for heating the body of water, the boiler further including a sub chamber which contains some of the water of the body of water or is in hydraulic communication therewith, so that such water in the sub chamber will essentially be at the same temperature as the body of water, a second heating means for heating such water int he sub chamber above the predetermined temperature of the body of water (which is in the region of boiling point) so that such water in the sub chamber can be made readily to give off steam which fills and/or creates a head space in the sub chamber, such head space being substantially closed except for a steam dispensing outlet through which steam can issue, said steam dispensing outlet being such as to be locatable in fluent material contained in a vessel for the steam heating of such fluent material, and operating means for the selective dispensing water and steam from water outlet and steam dispensing outlet.

5. A water boiler according to claim 4 wherein the second heating means is in the sub chamber, and is operable selectively by the operator of the equipment.

6. A water boiler according to claim 5, wherein the second heating means is arranged so that when operated, the control system of the apparatus may arrange for the first heating means of the body of water to be switched off.

7. A water boiler according to claim 6 wherein the bottom of the sub chamber is open and in free communication with the body of water tank.

8. A water boiler according to claim 7 wherein the steam dispensing outlet is adjustable so as to be swingable between an in-use and out-of-use position which facilitates inserting the nozzle in the heating vessel and removing it therefrom.

9. A water boiler according to any preceding claim wherein the boiler has a control system comprising temperature probes electronically sensing the temperature of the body of water at two levels e.g. a high level and a low level in order thermostatically to control the operation of the boiler for high demand and low demand, and in order to give an indication when the apparatus is ready for producing steam on demand.

10. A water boiler according to any preceding claim including a break tank and water reservoir, for preventing the flow of hot water back to the mains.

11. A water boiler substantially as hereinbefore described with reference to the accompanying drawings.