IL142377A - Temperature-sensing arrangement for domestic water heating system, and method for assembling the same - Google Patents

Abstract

A method for introducing a temperature sensing unit (17B) into a water tank (1), comprising the steps of: providing a tube having distal and proximal ends; mounting within the tube at least one temperature sensor; inserting the tube including the at least one temperature sensor through an opening in a pipe (104) leading water to or from the tank into the space of the tank; sealing the opening in such a manner as to enable to temperature sensing unit containing measurement wires connected to the said sensor(s) to extend out of the opening, while preventing leakage of water through the said opening. 2356 י" ד באלול התשס" ד - August 31, 2004 פירוט זה נבחן בהתאם לתקנה 35 לתקנות הפטנטים, תשכ" ח-1968 This specification was examined in accordance with regulation 35 of the Patent Regulations, 5728-1968.

Description

Ref 12782/01 "7ΊΠ n n 1? nrrun nrirzi DIITTI ΏΌΊΏΏ rmoisma nvm1? nro TEMPERATURE-SENSING ARRANGEMENT FOR DOMESTIC WATER HEATING SYSTEM, AND METHOD FOR ASSEMBLING THE SAME TEMPERATURE-SENSING ARRANGEMENT FOR DOMESTIC WATER HEATING SYSTEM. AND METHOD FOR ASSEMBLING THE SAME Field of the Invention The field of the invention generally relates to electrical home appliances. More particularly, the invention relates to a temperature sensor for domestic water heating system, and a method for assembling the same.

Background of the Invention Hot water is an essential commodity in the modern world, and a water heating system is an appliance commonly used in households throughout the world.

In some countries where the price of the energy is negligible, it is common to activate the water heating system all day, resulting in a significant waste of energy.

In other countries, where energy is relatively expensive, solar energy is used for heating the water. However, the solar energy cannot generally provide hot water 24 hours a day, 365 days a year, and therefore complementary heating involving energy consumption is required. The source of energy for this purpose is, in most cases, electricity or gas.

In order to save energy, activation of the water heating is on a need-only basis. However, in most water heating systems of the prior art, the user is not provided with any indication regarding the temperature of the water in the tank, and moreover, he has no indication whatsoever as to how long the heating system has to be ON in order to provide water in the desired amount at the desired temperature. Generally, this results in the user activating the heating element of the system for a longer time than necessary, resulting in wasted energy, or a shorter time than necessary, resulting in a colder and insufficient amount of water than desired. Furthermore, even after the water heating is presumably completed, the user has no indication of the water temperature in the tank, and must open the tap and wait a relatively long time for regulating the temperature, resulting in a waste of water.

The lack of accurate temperature indication of the water in the tank, and the inability to plan in advance the necessary amount of water and its temperature causes inconvenience, and waste of energy and water. In cases wherein the user constantly activates the water heating throughout the day and night, there is even more energy waste, particularly in times when there is no need for hot water. This energy waste is added to the energy loss resulting from the temperature difference between environment and the water in the tank, which in many cases is significant.

Of course, there are times where a user requires a relatively higher temperature than other times. In the systems of the prior art, pre-planning of the water temperature is either unavailable, or unsatisfactory. In conventional water heating systems of the prior art, and particularly for safety purposes, there is an adjustable thermostat mounted in a pocket in the water tank, which senses the water temperature, and disconnects the electrical supply when a pre-assigned maximum - -temperature is reached. However, in this case, the regular user does not have access to the thermostat, or control over the pre-assigned temperature.

Fig. 1 shows a hot water tank commonly used in systems of the prior art. It should be noted that throughout this application the common components utilized in different embodiments are referred to by numerals with a same prefix but with a different suffix. The water tank 1 comprises an electric heating unit 3 for supplying energy to the water. Heating unit 3 is essentially a resistor, heated by an electric current flowing through it, and transferring heat to the surrounding water. The water tank further comprises in its lower part an inlet water pipe 8, and in its upper part an outlet water pipe 9. Two optional water pipes 104 and 105 are included in those standard water tanks that are designed to operate with solar heat collectors. Pipe 105 introduces hot water from the collector to the tank. Pipe 104 enables the cold water to exit to the solar collector. Metal flange 2 at the bottom of the tank supports the heating unit 3. Also supported by the flange is a metal sleeve 4, serving as a pocket for a standard thermostat. Insulating layer 5 blocks heat transfer to the surroundings. Thin metal 10 encloses the tank and the insulating layer 5. Remote ON/OFF switch 6, is usually located in an easily accessible place, and generally comprises a red indication that lights up when the switch is ON. When the switch is ON and the water temperature rises to the preset temperature of the thermostat, the thermostat disconnects current to unit 3. When the water temperature falls below said preset temperature, the thermostat reconnects the current to the heating element.

Fig. 2 shows a prior art system that further comprises a heat concentrator 7 in the water tank. The heat concentrator 7, which is used only in a vertically oriented tank, is a cup -like device made of any suitable material, mechanically connected to the bottom of the water tank. The heat concentrator 7 has openings at its lower part 19 for enabling water passage, and at its upper part an additional outlet opening 20. The heat concentrator 7 encloses the heating unit 3 and the thermostat 4. When the heating unit 3 is activated, hot water in concentrator 7 flows to the upper opening 20, and cold water flows through the lower openings 19 to the concentrator, creating water circulation. Layers of hot water are therefore concentrated at the upper part of the water tank. After a long period of heating, all the water in the tank becomes sufficiently hot, and the water temperature in different parts of the tank is relatively homogenic. Generally, it is common to use a heat concentrator 7 in water tanks of 80 liters or more.

Prior art US 6,002, 114, filed September 15, 1998, discloses a water heating system which comprises: 1. A water tank with four heating elements; 2. Temperature sensing devices for checking the temperature at the inlet and outlet of the water tank; 3. A sensor for checking the water flow rate at the inlet pipe of the tank; 4. CPU receiving sensor indications, for activating/deactivating said four heating elements, further comprising a circuitry for detecting failures; and 5. A display panel for showing the user the temperature of the water leaving the tank.

More particularly, US 6,002,114 deals with a commercial heating system having four electric heating elements, and a plurality of sensors. The heating elements are activated according to the water temperature at the inlet and outlet of the tank, while further considering the inlet water flow rate.

US 5,556,564 discloses a domestic water heating system having a unit for controlling the water temperature. The said system comprises: 1. Three temperature sensors, a first sensor at the top, next to the outlet of the water from the tank, a second in the middle of the tank, and a third at the bottom of the tank next to the water inlet; 2. A display panel showing the temperature measured by the upper sensor, and enabling the user to set the required temperature of water leaving the tank; 3. Two light indicators which deactivate when the middle and the lower sensors measure temperatures above the set temperature. The light indicators indicate to the user when there is enough water in the tank for use. 4. The hot water tank and the control panel are distant one from the other, and are connected by only two electric wires. The same two electric wires provide the power to the heating element, and transfer the low voltage temperature indication from the upper sensor in the tank to the control panel.

FR 2 539 238 discloses a control method and device for an apparatus for heating a fluid to reach a predetermined temperature. The device comprises a central control unit receiving a signal from a temperature probe which identifies the temperature of the fluid, a storage unit for storing a characteristics data of the apparatus used, and a circuit for setting a predetermined temperature. The central control unit tries to activate the heating so that the fluid will reach the predetermined temperature at the predetermined time. The invention is particularly useful in electric water heating systems. The system of this patent particularly intends to activate the heating durin low-rate electrical periods, for example, overnight, weekends, etc. This publication identifies the periods of low-cost electric energy in order to activate the heating particularly during these periods. The system follows the unclear and undefined expressions: TH=TF-TD, and 1< K + ta. TH is the temperature at the end of the low cost electric energy period. TF is the time at the end of the low cost electric energy, TD is the present time, K is a factor describing the intensity of the electric power at the heating element and the water volume in the tank. This formula cannot determine the time required to heat the water in the tank. All this is available for one cycle a day. The system also enables manual heat activation for times when the energy cost is higher.

US 4,568,821 discloses still another remote water heating system. The system comprises two water tanks, one tank solar heated, the other heated by electricity, oil or gas. The system comprises two temperature sensors located at the outlet pipes of each water tank. The controller of said system uses a 24-hour clock, and is assembled with solid state electronic components.

Pending Israeli Patent Ap plica. Liu Π No. 137546, entitled "Programmable Domestic Water Heating System", by the same inventors of the present application, discloses a method and system for heating water that utilizes the specific heat of the water for scheduling the time and duration of the heat activation.

All the above prior art systems are designed to provide better control over water heating systems, and to save energy. However, none of the above publications relates to the manner of assembling water temperature sensors in domestic hot water tanks. The inventors of the present application have found that the manner of assembling the temperature sensing devices, and their location is essential for obtaining accurate temperature sensing and for obtaining energy and water saving.

It is therefore an object of the invention to increase energy and water saving in a domestic water heating system.

It is -another object of the invention to provide to the user of the heating system a better control and more reliable indication relating to the temperature of the water in the tank .

It is still another object of the invention to allow easier assembling of the sensors of the invention in existing water heating systems of the prior art, on site.

- - Summarv of the Invention The invention relates to a method for introducing a temperature sensing unit into a water tank, which comprises the steps of: (a) Providing a tube having distal and proximal ends; (b) Mounting within the tube at least one temperature sensor;, (c) Inserting the tube including the at least one temperature sensor through an opening in a pipe leading water to or from the tank into the space of the tank; and, (d) Sealing the opening in such a manner as to enable the temperature sensing unit containing measurement wires connected to the said sensor/s to elongate out of the opening, while preventing leakage of water through the said opening.

The invention further relates to a water heating system which comprises: (a) A water tank having a plurality of pipes leading water into or out of the tank; (b) At least one temperature sensing unit in a form of a "tube within the hollow of which at least one temperature sensor is mounted; (c) A heating device for heating the water, when activated; and (d) A control unit receiving information regarding the temperature of the water from the said temperature sensing unit, and for activating accordingly the heating device. The system is characterized in that the temperature sensing unit/s are introduced into the space of the water tank from within an opening in one of said pipes, and wherein said opening is then sealed in such a manner as to prevent leakage of water through said opening while letting the temperature sensing unit containing the measurement wires coming from the sensing device/s to penetrate through the sealing.

- - Preferably, a T connector is connected to the pipe with the temperature sensing unit, one end of said T connector forms the said opening with sealing, the other two ends of the said T connector lead water to or from the tank.

Preferably a cap with a bore is used at the said opening, the bore is sealed by a sealing material, while letting the temperature sensing unit containing measurement wires coming from the sensor/s to penetrate through the sealing.

Preferably, the pipe through which the unit is introduced into the tank is the pipe leading hot water out from the tank.

Preferably, one temperature sensor is located at the distal end of the unit, away from the sealed opening and within the 'space of the tank. Alternatively, a plurality of temperature sensors are mounted along the unit, to measure temperatures at different levels of the water in the tank.

Preferably, each temperature sensor transforms a change in temperature into a proportional change in voltage.

Brief Description of the Drawings - Fig.1 illustrates a domestic water heating system according to the prior art; - Fig. 2 illustrates another domestic water heating system according to the prior art; - Fig. 3 illustrates an installation of a temperature-sensing device in a water tank of the type of Fig. 1; - Fig. 4 illustrates an installation of a temperature-sensing device in a water tank of the type of Fig. 2; - Fig. 5a illustrates a temperature sensing unit with one temperature-sensorinside, according to a first embodiment of the invention; and - - Fig. 5b illustrates a temperature sensing unit with three temperature sensors inside, according to a second embodiment of the invention.

Detailed Description of Preferred Embodiments The invention provides a domestic water heating system with an improved manner and accuracy of sensing the temperature of the water in the water tank. Figures 3 and 4 illustrate two alternatives of installing the one or more temperature sensors in the water-heating tank.

According to the present invention, the one or more sensors are mounted within a tube-shaped a temperature sensing unit, which inserted into the tank via one of the existing pipes leading water to or from the tank.

In Fig. 3 a temperature sensing unit 17B is inserted via an existing water pipe 104 into the water tank 1. In some cases,' for example, when heat collectors are not in use, there may exist unused pipes, in this case pipes 104 and 105, connected to the tank, that are sealed by a cap. According to the invention, the cap is removed, and a temperature sensing unit 17B is inserted through pipe 104. The temperature sensing unit may include one or more temperature sensors, for measuring the temperature of the water, at different levels within the tank. Each temperature-sensor is connected to at least two wires for providing electronic indications regarding the temperature it measures. The wires of the temperature sensors are connected to a control circuit (not shown) that controls the activation of the heating system. The cap 102A is preferably a hexagonal-shaped cap having a bore 75 in its center. A conventional sealing material is used for sealing around the tube forming the temperature sensing unit, preventing the passage of water out of the tank.

It should be noted that the diameter of the temperature sensing unit 17B is generally much smaller in comparison with the diameter of pipe 104, essentially in the range of no more than 1/3 or 1/4 of the diameter of the pipe.

The temperature sensing unit 17B, including the one or more temperature sensors, can optionally be introduced into the water tank via a pipe in use. Fig. 4 shows such a case in which the temperature sensing unit 17A is introduced into the water tank via the outlet of hot water pipe 9. In that case, a T-connector 101 is used for enabling the introduction, through a first side of it, of the temperature sensing unit 17A into the water tank, while allowing the regular flow of water to pass into the hot water supply pipe 103C. The cap 102B is preferably a hexagon-type cap, similar to the cap 102A of Fig. 3, with a bore 77 through which the temperature sensing unit passes. A sealing material is used to prevent leakage of water through bore 77. Λ The diameter of the temperature sensing unit 17 A is essentially small in comparison with the diameter of the pipe 9, not to significantly disturb the flow of the water through pipe 9. It has been found by the inventors that a diameter of up to about 1/3 of pipe 9 does not cause a significant disturbance to the flow of water through pipe 9 and pipe 103.

It should be noted that the term "temperature sensor" used herein refers to any type of temperature measuring means.

Figs. 5a and 5b illustrate how the temperature sensors 107 are assembled within temperature sensing unit 17. In Fig. 5a, one temperature sensor 107 is assembled within a temperature sensing unit 17A. The sensor itself is indicated as numeral 107, and numeral 108 indicates a sleeve that encloses the electrical wires 109, that are connected to a control circuit that controls the activation of the heating when necessary. The upper portion of temperature sensing unit 17A is positioned in the water tank, and the wires 109 are outside the water tank, being connected to the control circuit (not shown). Fig. 5b similarly illustrates how three sensors 107A, 107B, and 107C are assembled within the temperature sensing unit 17B, at different heights, for enabling the temperature measurement at different levels of the water within the tank.

Preferably, the temperature sensors are of the type PT 100, having each three output wires 109.

- - The invention saves the need to provide a pocket (or sleeve) 4 in the water tank for a thermostat or a temperature sensing device, as according to the invention the insertion of the temperature sensing unit is made through an existing opening of a water pipe. Moreover, the temperature measuring has been found by the inventors to be much more accurate due to the following reasons: a. In the water tanks of the prior art it is essentially impossible to assure that a thermostat or a temperature-measuring device which is inserted into the pocket 4 will reach the top of the pocket 4A, close to the area of interest in which the temperature measurement is desired. Moreover, in order to obtain a relatively reliable measurement, it is desirable for the measuring device to touch the metal top 4A of the pocket 4, which, as said could not be assured. According to the invention, there is a direct contact between the sensing device and the water. b. According to the invention the "one or more temperature sensors can be designed to be mounted essentially at any height, and at almost any location within the water tank. c. In the prior art tanks with a pocket 4 there is essentially no way of measuring the temperature by more than one sensing de_vice. at different levels of the water.

The invention provides a method for introducing one or more temperature sensors within one or more temperature sensing units into a water tank. The method of the invention is useful in both existing water tanks and in future water tanks. In the first case, the introduction of the temperature sensing units according to the invention provides a more accurate measuring. In the latter case, the introduction of the temperature sensing units according to the invention also eliminates the need to provide a dedicated pocket for a temperature-sensing device, therefore reducing the cost of production of the tank. Moreover, the invention is simple, and can be easily carried out into practice at low cost.

While some embodiments of the invention have been described by way of illustration, it will be apparent that the invention can be carried into practice with many modifications, variations and adaptations, and with the use of numerous equivalents or alternative solutions that are within the scope of persons skilled in the art, without departing from the spirit of the invention or exceeding the scope of the claims.

Claims (10)

12782/01

1. A method for introducing a temperature sensing unit into a water tank, comprising the steps of: - Providing a tube having distal and proximal ends; - Mounting within the tube at least one temperature sensor; - Inserting the tube including the at least one temperature sensor through an opening in a pipe leading water to or from the. tank into the space of the tank; - Sealing the opening in such a manner as to enable the temperature sensing unit containing measurement wires connected to the said sensor/s to elongate out of the opening, while preventing leakage of water through the said opening.

2. A water heating system comprising: A water tank having a plurality of pipes leading water into or out of the tank; At least one temperature sensing unit in a form of a tube- within the hollow of which at least one temperature sensor is mounted; A heating device for heating the water, when activated; and A control unit receivin information regarding the temperature of the water from the said temperature sensing unit, and for activating accordingly the heating device; Characterized in that the temperature sensing unit/s are introduced into the space of the water tank from within an opening in one of said pipes, and wherein said opening is then sealed in such a manner as to prevent leakage of water through said opening while letting the temperature sensing unit containing measurement wires coming from the sensing device/s to penetrate through the sealing. :

3. A system according to claim 2 wherein a T connector is connected to the pipe with the temperature sensing unit, one end of said T connector forms the said opening with sealing, the other two ends of the said T connector lead water to or from the tank.

4. A system according to claim 2 wherein a cap with a bore is used at the said opening, the bore being sealed by a sealing matea^al, while letting said temperature sensing unit containing measurementwires coming from the sensor/s to penetrate through the sealing.

5. A system according to claim 2 wherein the pipe through which the unit is introduced into the tank is the pipe" leading hot water out from the tank.

6. A system according to claim 5 wherein one temperature sensor is located at the distal end of the unit, away from the sealed opening and within the space of the tank.

7. A system according to claim 2 wherein a plurality of temperature sensors are mounted along the unit, to measure temperatures at different levels of the water in the tank.

8. A. system according to claim 2, wherein each temperature sensor transforms a change in temperature into a proportional change in voltage. 12782/01 -17-

9. A method according to claim 1, essentially as described and illustrated.

10. A system according to claim 2 essentially as described and illustrated. LU3EZATTO ft LUZ2AT O