GB2306209A

GB2306209A - Preventing scaling of level sensing electrodes in water boilers

Info

Publication number: GB2306209A
Application number: GB9620867A
Authority: GB
Inventors: Stephen Goldacre; Malcolm Coles
Original assignee: CALOMAX
Current assignee: CALOMAX
Priority date: 1995-10-12
Filing date: 1996-10-07
Publication date: 1997-04-30
Anticipated expiration: 2016-10-07
Also published as: GB9520938D0; GB2306209B; GB9620867D0

Abstract

A water boiler for making hot beverages and liquid foodstuffs comprises a body 10 for the main bulk of water, heating means (not shown) for heating the water, and electrodes 42,44,46 for sensing the level of the water, the electrodes being positioned in a separate chamber 36 which is in communication with the cold water feed 32 so that the body and the chamber are supplied with cold water simultaneously. These electrodes will be less likely to scale up than were they positioned in the body 10. Preferably the water is fed to the body and the chamber via a solenoid in batches. An electrode may additionally be provided in the body for detecting the build up of scale in the body. A stand by sensor 56 may control the temperature of the water in the body whilst the water is at the level of the upper electrode 44.

Description

Improvements relating to water boilers This invention relates to water boilers, especially those water boilers which are used for the supply of hot water for making beverages such as tea, coffee and the like, or for the making of liquid foodstuffs, such as soups and mineral supplements.

Water boilers are of course well known and are used in cafeterias, hotels and recreational clubs, throughout the country. It is a fact however that the water in the United Kingdom and no doubt in other countries varies in hardness from location to location, and that these water boilers become "scaled up" and have to be cleaned periodically. The scaling is a deposit from the water, and its presence is generaily undesirable, as at best it affects the performance of the boiler, but in more specific cases, it can lead to the rendering ineffective the detection of the water levels in the main body of the boiler in which the water is contained, insofar as the main body usually houses level detection electrodes which are used to control the supply of the water to the boiler.

If these electrodes beccme furred up with scale, they cease to perform their function effectively.

This invention in at least one aspect seeks to provide an improved water boiler wherein the aforesaid disadvantage is obviated or mitigated.

According to the invention there is provided a water boiler comprising a body for holding water to be heated, heating means for heating the water in the boiler body, and level detection means for detecting the level of water in the body, characterised in that the level detection means comprises electrodes in a second chamber which is in hydraulic communication with the body by a connection which causes incoming cold water to flow simultaneously to both the body and the chamber, whereby the water in the chamber which serves as the means for controlling the water level in the body, remains at a temperature which is less than that in the body.

The advantage of the above arrangement is that the electrodes, being in cooler water than the water in the body will tend to scale up less than the inside of the body or indeed not at all, if the water in the chamber can be kept cool enough.

Preferably, the chamber is a tube which extends vertically and is connected at its lower end to the cold water mains, as is the bottom of the body which lies adjacent the said lower end of the tube. The mains preferably is connected through a solenoid valve to the body and the chamber.

n a particularly preferred arrangement, the solenoid valve is controlled so as to ensure that the water is supplied to the body and chamber in batches when the body is being filled or replenished and the boiler may also have a control circuit connected to the heating means to provide that as each batch of water is charged into the body, it is heated to a required temperature before the next batch is introduced and so on.

Also, the boiler may have a further temperature sensitive device which acts as a standby sensor keeping a watch on the temperature of the water of the body whilst the water is at the level of the upper sensor, so that when the standing water cools, during normal operation or from the boiler having been switched off overnight, the heater maintains the desired pre-set temperature in the body.

As a further feature of the invention which can also form a second invention by itself, there may be a body electrode in the body for detecting the build up of scale in the body itself. This provides an advantage that a warning signal of scale build up in the body can be obtained readily.

The boiler may be a wall mounted boiler or a ccunter mounted boiler and will be provided with the conventional water supply and venting arrangements.

Although the following temperatures are not to be taken as limiting of the invention, they do give an idea of the typical levels of temperature which may be involved.

TEMP OF THE WATER IN THE BOILER: 98"C TEMP OF THE WATER IN THE CHAMBER: 60"C An embodiment of a boiler according to the invention will now be described with reference to the accompanying drawings, wherein; Fig. 1 is a front view of the boiler with the cover removed; and Fig. 2 is a side view of the boiler shown in Fig. 1 with the cover remove.

Referring to the drawings, reference 10 represents a box body which is made of stainless steel. It is of rectangular form and it has a front 12, a back 14, a left side 16, a right side 18, a bottom 20 and a top 22. The front 12 has, as is conventional, a dispensing nozzle 24 by which water is dispensed into, for example, a cup or jug. The body 10 preferably is covered in heat insulating cladding.

The body 10 is supplied with cold water from the mains via a supply pipe 26 which is in turn connected to a solenoid valve 28 whose operation is controlled by a printed circuit board 30. From the solenoid valve 28, the incoming water passes into a feed pipe 32 which delivers the water to the body 10 at the lower region of the left side 16. The pipe 32 has a branch arm 34 which leads into a vertical tube 36 forming a cold or cool water chamber. Chamber 36 extends for approximately the same height as the body 10 and it contains level sensing devices which serve to control the eight of the water in the body 10 as will be described.

At the top of the tube 36, there is a condenser 38 into which steam from the body 10 passes. Such steam flows through a steam pipe 40 connecting the top of the body 10 with the condenser 38. The top of the tube 36 also connects with the condenser 38. The steam which is condensed is unabie to flow into tube 36 due to the internal arrangement of condenser 38, and flows back into the body 10.

In the tube 36 there are three electrode sensors, namely a low level sensor 42, a high level sensor 44 and an emergency sensor 46. The body has electric heating means (not shown) which serves to heat the water in the body 10 and the heating means is controlled by the circuit board 30.

The arrangement operates as follows.

If there is no water in the body 10, when the unit is switched on, a first indicator light 48 is switched on and it flashes. The low level sensor 42 senses that there is no water in the unit and prevents the heating means from operating. The solenoid valve 28 opens and a batch of water is allowed to flow into the body 10 until the water level reaches the low level sensor 42, whereupon the heating means is switched on and begins to heat that batch of water. The heating means is located below the low level sensor 42 and therefore if the low level sensor 42 is covered with water so is the heating means. As soon as that batch of water is up to the desired temperature the indicator light 48 switches from a flashing mode to a constant mode indicating ready, the solenoid valve 28 is again operated, and a further batch of water is introduced 2nto the body 10. As soon as that batch 15 up to the desired temperature, the solenoid valve 28 is again operated, and a further batch of water is introduced into the body 10. This is repeated until the water level reaches the upper sensor 44.

With the boiler in the ready condition, as indicated by the constant illumination of light 48, water can be drawn off as required. Should the water level at any time fall below that of the sensor 44, it will be automatically replenished in the manner above described. In the normal operation of the boiler, the boiler will always have some standing water therein, even when it is switched off overnight. In the morning, the standing water may have cooled, and when the boiler is initially switched on, light 48 will indicate the flashing mode asking the user to wait until such times as the heating means brings the standing water up to temperature. Water can be drawn off even although the level of water in the body 10 is not at the level of sensor 44, but during this time, the boiler will be working to replenish the water so as to raise the water level to sensor 44.

Should sensor 44 'not function properly so that the water level rises to sensor 46, an indicator light 50 is illuminated to indicate a fault so that the boiler can be serviced. The illumination of the warning light may be flashing or constant as required and if one mode of fault warning is indicated by flashing, another fault mode can be indicated by constant illumination of light 50. Thus, as indicated herein the equipment may additionally have a scale sensor inside the body 10 which can be used to indicate a fault warning via light 50 in the event that the build up of scale inside the body becomes too great.

It will be noticed that the chamber 36 s a tube located outside the body 10, and that as cold water enters the body 10, it simultaneously enters the tube 36. Both tube 36 and body 10 will ultimately be vented to atmosphere, for example through the vent pipe 52 and therefore the levels of water in the chamber 36 and body 10 will be essentially the same. Sensing of the levels by the sensors 42, 44 and 46 in the chamber 36 is therefore sensing of the water levels in body 10.Because chamber 36 is outside body 10, the water contained therein will always be cooler than that in the body 10 and therefore there will be less tendency for the sensors 42, 44 and 46 to scale up, and they will operate therefore more reliably and for a longer period than in the case of the conventional arrangement wherein the sensors are contained in the body 10, providing considerably enhanced operation of the boiler.

The two temperature sensing devices in the body 10 are indicated by reference numerals 54 and 56. Reference numeral 54 indicates a fill up temperature sensor, whilst 56 indicates a standby temperature sensor. These sensors preferably are thermistors. Thermistor 54 is located to the underside of the inlet of pipe 32 into body 10, so that the incoming water will fall on the thermistor 54, which causes the temperature detected by the thermistor 54 to fall to a level which causes switching on of the heater. When the water sensed by the thermistor 54 reaches a predetermined elevated temperature, the heater is switched off.

The standby thermistor 56 serves to check the temperature of the standing water in the body 10 whilst the water is at the level of the upper sensor 44, maintaining the temperature of the water at the desired pre-set temperature sy operating the heater.

The boiler may also have a pressure relief valve to relieve excess pressure in the body 10, and a temperature cutout (on the condenser 38) for shutting down the machine automatically in the event that too high a temperature is reached.

Claims

CLAIMS.

1. A water boiler comprising a body for holding water to be heated, heating means for heating the water in the boiler body, and level detection means for detecting the level of water in the body, characterised in that the level detection means comprises electrodes in a second chamber which is in hydraulic communication with the body by a connection which causes incoming cold water to flow simultaneously to both the body and the chamber, whereby the water in the chamber which serves as the means for controlling the water level in the body, remains at a temperature which is less than that in the body.

2. A water boiler according to claim 1, wherein the chamber is a tube which extends vertically and is connected at its lower end to the cold water mains, as is the bottom of the body which lies adjacent the said lower end of the tube. The mains preferably is connected through a solenoid valve to the body and the chamber.

3. A water boiler according to claim 1 or 2, wherein the solenoid valve is controlled so as to ensure that the water is supplied to the body and chamber in batches when the body is being filled or replenished.

4 A water boiler according to claim 1, 2 or 3, wherein the boiler has a control circuit connected to the heating means to provide that as each batch of water is charaed into the body, it is heated to a required temperature before the next batch is introduced and so on.

5. A water boiler according to any preceding claim, wherein the boiler has a further temperature sensitive device which acts as a standby sensor keeping a watch on the temperature of the water of the body whilst the water is at the level of the upper sensor, so that when the standing water cools, during normal operation or from the boiler having been switched off overnight, the heater maintains the desired pre-set temperature in the body.

6 A water boiler according to any preceding claim, wherein there is a body electrode in the body for detecting the build up of scale in the body itself.

7 A water boiler according to any preceding dlaim, wherein the boiler is set to operate at the following temperatures;- TEMP OF THE WATER IN THE BOILER: 980C TEMP CF THE WATER IN THE CHAMBER: 600C

8. A water boiler comprising a body for holding water to be heated, heating means for heating the water in the boiler body including a body electrode in the body for detecting the build up of scale in the body itself.

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