GB2143625A

GB2143625A - Hot water dispenser

Info

Publication number: GB2143625A
Application number: GB08416653A
Authority: GB
Inventors: Cecil Hayes
Original assignee: Still & Sons Ltd W M
Current assignee: Still & Sons Ltd W M
Priority date: 1983-06-30
Filing date: 1984-06-29
Publication date: 1985-02-13
Also published as: GB2143031B; GB8416653D0; GB2143625B; GB8317847D0; NL8402049A; GB2143031A; NL8402048A

Abstract

A hot water dispenser of a substantial size, that is with a capacity of at least one litre, having a source of cold water (74,102,228) to replenish a hot water container (50,100,200). A thermostat is provided to detect the heat of the water to be dispensed from the container, the thermostat controlling both the switching on of a heater element (54, 106, 204) in the container and the closure of an on/off valve (62, 126, 236) controlling the supply of cold water to control the temperature of water to be dispensed to prevent it dropping more than a preferred amount of about 5 DEG and to ensure the hot water container always has a ready supply of dispensable hot water with the advantage that only small amounts of cold water enter the hot water container at any one time. <IMAGE>

Description

1 GB 2 143 625 A 1

SPECIFICATION

Hot water dispenser The present invention relates to hot water dispensers for dispensing a quantity of water for making a beverage.

In known hot water dispensers used by the catering industry, a container is provided in which an immersion heater or kettle type heater element is located. To use the dispenser an outlet of the container controlled by a tap is opened and the water level drops, a plumbed in supply of cold water is then opened to replenish the container water level.

However, a significant period then elapses before the container water contents can be brought up to the requisite heat for the next dispensing operation.

A hot water dispenser according to the present invention comprises a hot water container having a capacity of at least one litre, an inlet connected to a source of cold water to replenish the container during andlor after a dispensing operation, a thermostat arranged to detectthe heat of the waterto be dispensed, the thermostat controlling both the switching on of the heater element and the closure of the on/off valve so that when the heat of water in the container drops substantially below the dispensing temperature the on/off valve prevents cold water entering the container. The normal range of temper- atures between maximum and minimum dispensing temperatures is not greater than 1WC and normally about 5'C.

The advantage of the dispenser according to the invention is that cold water replenishing the contain- er water level is only allowed to enter the container after or during dispensing in small amounts so that the container water temperature only fails slightly but not substantially below the dispensing temperature. In this way the thermostat ensures the dispen- ser always provides a ready supply of hot water at or near the dispensing temperature.

In one preferred embodiment a water level detector is provided which is arranged to ensure closure of the on/off valve when the level of water in the container reaches a predetermined upper level. in one embodiment the detector is provided in a separate container to the hot water containerwith intercommunication for water between the two containers. In this way priming or the balance in the hot water container does not affect the separate container's water level. In a second embodiment this problem is overcome by using a pair of height spacedlevelprobes.

The use of the thermostat to control the flow of water into the container as well as the heater element ensures that as the heat level drops cold water is prevented from entering the container and thus cooling the water already in the container. Thus the container water is always kept at a high tempera- ture suitable for dispensing.

In a preferred embodiment the dispenser has a water level detector arranged to close or prevent the opening of the solenoid operated on/off valve to prevent over filling of the container.

The water level detector is preferably provided in a 130 separate chamber to the container.

Three embodiments of the invention will now be described by way of example with reference to the accompanying diagrammatic drawings in which:- Figure 1 shows a cross section of a first embodiment of the invention, Figure 2 is a circuit diagram for the electrical controls of the second embodiment shown in Figure 1 1 Figure 3 shows a cross-section of a second embodiment of the invention, Figure 4 is a circuit diagram for the electrical controls of the third embodiment shown in Figure 3, Figure 5 is a cross-section of a third embodiment of the invention, Figure 6 is a circuit diagram for the electrical controls of the third embodiment, and Figure 7 is a circuit diagram showing further details of the circuitry of Figure 6.

In the first embodiment shown in Figures 1 and 2, a tank 50 forming a hot water container of typically about 5.7 litres capacity has a draw-off tap 52 located about half way up so that an approximate equal volume of the tank is above and below the tap. A cast-in element heater 54 forms the base of the tank and just above the base a thermostat phial 56 is mounted in the tank wal 1 and is connected to a controller 58. A conduit 60 extends through the heater 54 in the base to a shut-off valve 62 operated by solenoid 64. Elements 66 of heater 54 are connected by lines 68 to controller 58 via a thermal safety cut-out 70 in heater 54.

A further conduit 72 connects valve 62 to a cold water coontainer 74 having a typical capacity of 2.8 litres. Conduits 72 and 60 form a connecting means between the cold water container 74 and the hot water container defined by tank 50.

The controller 58 as seen in Figure 2 comprises an adjustable thermostat switch 76 controlled by phial 56 and preset to switch from a position C to a position 0 when it reaches a preset upper temperature as adjustably set between WC and WC. The controller also has a relay 78 having a coil 80 and contact arm 82 moved by the coil between open contact A and closed contact B. Between contact A and neutral line 84 is a water ready lamp 86. Connected in supply line 88 is a main on/off 90 with indicator lamp 92. It will be seen from the circuit diagram that when the heater elements 66 are connected to the main supply through thermostat switch 76 being in the C position, solenoid 64 will not be powered and valve 62 will stay shut preventing any communication between the cold and hot containers.

In order to operate the appliance water is filled manually to a minimum level 94 and main switch 90 is switched on. Indicator light 92 illuminates and switch 76 which will be in position C allows elements 66 to be powered. Having set switch 76 to a predetermined temperature upper level the water in tank 50 will continue to heat up until that temperature is reached when switch 76 will move to position 0 deenergising the heater. Ready lamp 86 will then come on and relay coil 80 will hold arm 82 onto contact B. Valve 62 will then be opened by solenoid 2 GB 2 143 625 A 2 64.

In order to operate the appliance in a pour and serve manner, a flask of cold water is poured into the cold water container 74 and cold water is then allowed to flow into tank 50. The chilling effect of the cold water causes the thermostat switch move to C energising the heater and close the valve. This action repeats, allowing small amounts of water to enter as the thermostat switch modulates between 0 and C.

This continues until the level in container 74 equalises with that in tank 50. As water is drawn off from tap 52 the cold water will slowly level up controlled by the thermostat switch 76 thus ensuring the hot water tank is not flooded with cold water and so that the water in tank 50 remains with the thermostat modulation range of about 5'C.

A second embodiment is shown in Figures 3 and 4 in which a tank 100 forms a hot water container and a reservoir 102 forms a cold water container, bot- toms of the tank and reservoir being connected by a conduit 104 forming a connecting means. The tank 100 has a heater 106 forming the base and in which is or are cast-in a heating element or elements 108. A thermostat phial 110 is located above the base in the lower part of the tank below an outlet 112 controlled by a tap 114.

The element or elements 108 are connected to a controller 116 via a thermal safety cut-out 118 by leads 120.

The cold water container 102 is provided with a float switch 122 or other suitable water level control such as level probes. A main water supply 124 is connected to container 102 via a water inlet shut-off valve 126 controlled by a solenoid 128 which when powered opens the valve and when unpowered allows the valve to stay closed.

The controller 116 is connected to all electrical power source via leads 130 and 132 in which is a main supply switch 134. A power on/off indicator lamp 136 is connected across the switch and neutral lead 130. The controller comprises a thermal control switch 138 controlled by phial 110, a first relay 140 having a coil 142 actuating switch arms 144 and 146, and a second relay 148 with coil 150 actuating switch arms 152,154,156 and 158. A water ready indicator lamp 160 is connected between relay 148 and neutral line 130. The cold water level switch 122 with switch arm 162 is also connected between relay 148 and neutral supply line 130 so that when the water is less than full the arm 162 makes with contact R the circuit between the relay and line 130.

The second embodiment operates as follows:- The tank 100 is primed with cold waterto cover the heater suitably to minimum level 170 (a volume of about a litre) and main switch 134 is switched on. Switch arm 164 of thermostat switch 138 is in connection with contact C, relay 148 is unpowered with arms 156 and 158 on contacts N and Q respectively so that relay 140 is powered with coil 142 making arms 144 and 146 making with contacts D and F respectively. The heater element(s) 108 are thus powered, whilst the valve solenoid 128 is unpowered so the cold water valve 126 is shut. When the water reaches the predetermined temper- ature set on thermostat switch 138 (50'C - 95'C) arm 164 moves to contact 0 and coil 150 of relay 148 is powered, arms 152,154, 156 and 158 make with contacts H, K, M and P respectively and solenoid 128 powers to open valve 126. Heater element 108 remains powered and cold water flows through container 102 into tank 100 to cool the hot water until switch 164 makes with contact C normally at a temperature about 3 or 5'C below the set temperature. This heating and cooling of the tank water modulates between set temperature and the 3 to 5'C below the set temperature until filling the hot and cold water containers until the cold water container is full at level 172 when the arm 162 of level switch 122 breaks the circuit with relay 148 and relay 140 is deenergised with thermostat switch arm 164 made with contact 0. At this point the solenoid 128 and element(s) 108 are deenergised whilst relay 148 is energised. Lamp 160 is on indicating the water in tank 100 is at the predetermined temperature.

Hot water may then be drawn off through tap 114 and resupply is then commenced as soon as switch 122 detects water level in container 102 drops below the upper water level 172.

It will be appreciated that the arrangement of the second embodiment ensures that water is always in between the preset temperature and just below that temperature and that a supply of hot water is always ready for dispensing. The construction of the heater ensures that scale forming in the bottom of the hot water tank can be easily removed without removal of the heater.

Tank 100 has a capacity of above 1 litre normally 5.7 litres but may be as much as 45 litres and tank 102 has a capacity of 1.7 to 2.3 litres.

A third embodiment is shown in Figures 5,6 and 7 in which a tank 200 forming a hot water container has a draw-off tap 202 located towards the bottom. A cast-in element heater 204 forms the base of the tank and mounted just above the base and supported by the heater casting is a thermostat phial 206 connected to a controller 208. A conduit 210 extends through the heater 204 from a tank inlet 212 to a 'T' junction 214, a lower branch 216 of which extends to a drain plug 218 above a drip tray 220.

The other branch 222 of the'T'junction extends upwardly to a'T'junction 224just above An upper water level 226. This other branch 222 forms a gravity feed pipe from a conduit 228 which terminates at its upper end at'T'junction 224 and at its lower end at a water flow regulator 230. Regulator 230 is a known commercially available item for inhibiting pressure surges. Conduit 228 forms a small cold water container of small but nevertheless significant volume. The remaining branch 232 of the '7junction 224 extends upwardly to a vent 234 to atmosphere ensuring that the feed down branch 222 is by means of gravity, and prevents siphoning back.

Connected to regulator 230 is a solenoid operated valve 236 controlled by controller 208 so as to open or shut the supply of mains cold water from supply conduit 238.

The tank 200 is also provided with an overflow pipe 240 just above level 226, and a pair of vertically separated level probes 242 and 244, the upper 244 of which is atthe level 226.Thetopofthetank200is 3 GB 2 143 625 A 3 closed by a lid 246. On the front of dispenser easing 248 are controls which include a combined main on/off switch and indicator lamp 250, a water ready indicator lamp 252 and a thermostat temperature control 254 movable between any setting between 50'C and 95'C. A thermal safety cut-out 256 is provided on the bottom of heater 204.

The tank may be normally drained to a lower level 258 by switching off the main switch 250 and opening the tap 202. But complete drainage is by means of drain plug 218.

In the circuit diagram of Figure 6 there is shown the combined main onloff switch and indicator lamp 250 with its switch arm 260 and lamp 262. Also shown is a relay 264 (RLB) comprising a switch arm 266 operated by solenoid coil 268 with contacts S and T operable so that with no current through coil 268 the switch 266 makes with contact S. Thermostat control 254 comprises a switch arm 270 nominally on contact X until it reaches its setting when arm moves to contact W. Solenoid operated valve 236 comprises a solenoid coil 272 and valve 274. A control box 276 includes a further relay 280 (RLA) having a relay arm 278 movable from a nominally closed position on contact V to an open position on contact U and having a solenoid coil 282 controlled by a solid state circuit triggered by probes 244 and 242 through a suitable chip IC. This is shown in more detail in Figure 7.

The operation of the circuitry of the fourth embodi- 95 ment is as follows: The dispenser is first primed by filling the tank 200 to the minimum water level 258.

The dispenser is then switched on by means of switch 260 and the fact that it is switched on is indicated by the illumination of lamp 262. Switching 100 on energizes the water level controller 208 and the heater coils in heater 204. After a period of time depending on the setting of thermostat switch 254, the thermostat switch arm 270 will change overfrom the nominally closed position on contact X to the nominally open position on contact W. This will cause solenoid coil 272 of valve 236 to be energized and thereby allow water to be passed into tank 200 at a control flow rate via regulator 230. When sufficient water has entered tank 200 thermostat phial 206 will sense the fall in water temperature causing switch arm 270 to revert to its position on contact X to de-energise solenoid 272 thus closing valve 206. The water in the tank then heats up again and the cycle of opening and closing valve 236 continues until the water level reaches level 226 of the top water probe or senser 244 at this point switch arm 278 of control relay 280 in control box 276 changes over from its nominally closed position on contact V to its nomin ally open position on contact U to de-energize the coils of heater 204 and at the same time coil 268 of relay 264 causes arm 266 to move from contact S to contact Tto energize the water "ready" light 252.

The dispenser is now ready to be used and the water temperature is maintained at the correct temperature by the action of thermostat phial 206 and its control 254 energizing the heater 204 as required. To use the dispenser, heated water is drawn off by opening tap 202 to fill flask 6. The heated water is automatically replaced at a control rate so as to maintain the water temperature at the correct temperature in tank 200 by the combined action of probes 242 and 244 energizing the heater 204 and the thermostat control 254 energizing the solenoid coil 272 for valve 274 as required.

It will be appreciated that the logic arrangements in the controller 208 control the effect of probes 242 and 244 such that hunting of the control system about the upper water level 266 is avoided and the provision of two probes effectively acts as a dampening device in the event of water bubbling or surging between the probes.

Advantages of the third embodiment are that after the water "ready" light is energized hot water drawn off from tap 202 will have a temperature control within a relatively fine differential say about 3'C, of the thermostat arrangements. This dispenser is suitable for making hot beverages between any temperature between 50' and 95' by the setting of the thermostat control 254. The dispenser is generally easy to descale because of the type of water heated used and its location in the bottom of the heated tank as is more particularly described in our co-pending Patent Application No. 8317848 filed on the same date as the present application, the subject matter of which is incorporated herein by reference.

The capacity of the second and third embodiments'tanks 100 and 200 are much the same as that of tank 50 of the first embodiment, that is at least one litre and typically 5.7 litres, but possibly as much as 45 litres sufficient at any rate to fill flask 6 of about 1.7 litres (3 pints). The minimum levels 170 and 258 are typically such that about 1 litre remains in the tanks.

1. A hot water dispenser comprising a hot water container having a capacity of at least one litre, an inlet connected to a source of cold water to replenish the container during andlor after a dispensing operation, a thermostat arranged to detect the heat of the water to be dispensed, the thermostat controlling both the switching on of the heater element and the closure of an onloff valve controlling the cold water inlet so thatwhen the heat of the water in the container drops substantially belowthe dispensing temperature the on/off valve prevents cold water entering the container, also that when the tempera- ture rises to the dispensing temperature the inlet valve can open.

2. A dispenser as claimed in claim 1 wherein the thermostat ensures closure of the on/off valve before the water in the container drops more than 10'C.

3. A dispenser as claimed in claim 1 or 2 wherein a water level detector is provided and which is arranged to ensure closure of the on/off valve when the level of water in the container reaches a predetermined upper level.

4. A dispenser as claimed in claim 3 wherein the detector is provided in a separate container to the hot water container with intercommunication for water between the two containers.

5. A dispenser as claimed in claim 3 or4 wherein the detector comprises a pair of height spaced level 4 GB 2 143 625 A 4 probes.

6. A hot water dispenser substantially as described with reference to any one or more of Figures 1 to 4,6 and 7 of the accompanying drawings.

Printed in the U K for HMSO, D8818935,12,84,7102. Published by The Patent Office, 25 Southampton Buildings, London, WC2A 'I AY, from which copies maybe obtained.