US2115601A - Heating method and means - Google Patents

Description

E. WHITBY ET AL 2,115,601

HEATING METHOD AND MEANS A fil 26, 1938.

2 Sheets-Sheet 1 Filed March 11, 1932 INVENTORS E. Wkz'ibg Ii D. PaZZer ZJSeZsZwz 17.18. Easter flJMq/man A RNEY rawn-n O April 26, 1938. E. WHITBY ET AL 2,115,601

HEATING METHOD AND MEANS Filed March 11, 1932 2 Sheets-Sheet? INVENTORS E. PY/zz'iby' ZflflPedZer 3/9 ZYJ'SzZsZwz LElIes Zar BY d Ilka/Mn Patented Apr. 26, 1938 UNITED STATES PATENT OFFICE Pedler, Ernest Joseph Selston,

and Arthur Joseph Newman, Bristol, and Llewellyn Rolls Lester, Old Bracknell, England, assignors to Landis & Gyr, A-G., a corporation of Switzerland Application March 11, 1932, Serial No. 598,188 In Great Britain March 18, 1931 4 Claims. (01. 219-ss) The invention relates to a novel and useful method and means for heating materials in a fluent state and more particularly to such a method and means for controlling the tempera- 5 ture of a heated body of fluent material having a variable withdrawal and supply.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate one embodiment of the invention, and together with the description, serve to explain the principles of the invention.

0f the drawings:

Fig. 1 is a partially diagrammatic view in transverse vertical section of a heater embodying the invention;

Fig. 2 is a similar view of a,,modified form showing an electrically-controlled make-up valve;

Fig. 3 is a similar view of a modified.form

showing the make-up valve and the heating current controlled by the same thermostat; and

Fig. 4 is a similar view of a fourth modification wherein a make-up storage tank is eliminated.

The invention is directed to novel means for heating fluent materials such as fluids; solids in a flaky, granular, powdered or other fluent form; or mixtures of liquids and solids, which are capable of being regularly fed to a heating chamber. The invention also comprises a novel meth- 0d of controlling and maintaining the heat and/or temperature of a body of such materials. The invention is primarily applicable to the heating of fluent materials which are maintained and heated in a heating or storage chamber from which withdrawals of the hot fluid or the like are made from time to time and partially or wholly replaced by colder fluid. The replacing fluid is usually termed the make-up and this term will be so employed hereinafter.

The invention is more specifically directed to improvements in present methods and means for electrically heating water, and the hereinafter described embodiment of the invention is an electric water heater, although it will be understood that the broad features of the invention are also applicable to difierent types of heaters and to the heating and heat control of all materials designated above.

One of the primary objects of the invention is to provide a heater and a method of heating water or the like so as to prevent substantial reductions in the temperature of the supply of hot water by virtue of ingress of the cold water makeup consequent upon withdrawals of the hot wa ter. In accordance with the invention, the sup ply of the make-up is automatically controlled, preferably by thermostatic means, so that the make-up fluid is admitted to the heated body of fluid only when the temperature of said body exceeds a predetermined minimum, and the amount and/or rapidity of admission of the make-up is in proportion to the temperature and amount of fluid in the heated body, so that the predetermined temperature thereof may bemaintained substantially constant at all times. By thus regulating the ingress of make-up independently of the outflow or withdrawal of the heated fluid, the temperature of the latter can be maintained substantially as desired and there is never any appreciable cooling 01f of the heated fluid, regardless of the frequency of the withdrawals.

More specifically, the present preferred embodiment of the invention comprises an electric water heater for heating a body of water in a storage tank or container, the heater having its circuit controlled thermostatically, whereby the heating current will be cut off when the temperature of the body reaches the predetermined maximum and will be switched on when the temperature falls substantially below said maximum. The make-up water supply is connected with the heating and storage chamber by a thermostatically-controlled valve which is responsive to the temperature of the heated body of water. This valve is so controlled that cold make-up water will be admitted to the heating chamber only when the temperature of the heated body exceeds a predetermined minimum, and thereafter the admission of the make-up will be at a rate and for a time dependent upon the amount required to maintain the desired temperature and quantity of the heated water.

Furthermore, the invention is especially applicable to electric supply systems with restricted hours of supply for water heating purposes, such as those having heaters of the off-peak type,

Hence if any fluid is drawn off during the time when the supply current is switched off from the heater circuit, the temperature of this fluid, apart from radiation losses, is at the desired temperature and cannot be lowered by the inflow of cold make-up.

It will be understood that the foregoing general description and the following detailed description as well are explanatory and exemplary of the invention, but are not restrictive thereof.

Referring now in detail to present preferred embodiments of the invention, in Fig. 1 there is shown a heater of the type in which the makeup inlet valve is mechanically coupled to and operated by a thermostat. In accordance with the invention a cistern or water tank I is preferably formed with an inner heating and storage chamber 2 for containing and heating the body of hot water. The cistern preferably is constructed with an outer shell or casing and the space between it and the inner chamber 2 is preferably filled with suitable insulating material 3, as shown.

The embodied means for maintaining a supply of cold make-up water comprises a feed trough or tank 4, preferably mounted above the storage tank 2 as an integral part of the main cistern I, the tanks 2 and 4 being suitably insulated from each other as shown. Cold water is suitably admitted to the feed trough 4 through inlet pipe 6 which may be connected to a cold water supply main, and admission of the cold water to the trough is controlled by a suitable valve 5 which is responsive to the level of water in the feed trough by means of the float 5a and the connecting lever 5b. A suitable overflow pipe I is provided in the upper portion of the trough 4.

Means are provided for heating the body of water in the tank 2 and for controlling the maximum temperature of the water, comprising an electrical heating element 9 and an over-temperature thermostat I 0 which are suitably connected to the heating circuit I5 in a well-known manner, so that the thermostat controls the circuit switch (not shown). The heater 9 and thermostat II] are preferably disposed relatively near the bottom of the tank, so that they will always be immersed in water. For this purpose, the draw-off tap 8 is mounted substantially above the bottom of the tank and slightly above the level of the thermostat I0 so that a small amount of water, as shown, will always be maintained in the tank and immersing the heater and thermostat.

In accordance with the invention, means are provided for admitting make-up water from the trough 4 to the heating chamber 2 only when the temperature of the heated water reaches or slightly exceeds a predetermined minimum. As embodied, a supply tube II is provided between the trough 4 and the chamber 2 and passage of water from the tank 4 through the tube is controlled by a tapered valve I2, which is movable axially with respect to the tube I I and is mounted on the upper end of the tube-enclosed rod I3 as shown. The embodied means for raising and lowering the valve I2 comprises a thermostat I4 which is connected to the rod I3 at its lower end and near the bottom of tank 2. The thermostat may be of a known bi-metallic type, with the bimetals coiled into a spring to which the valve rod is attached and the connections so adjusted that the valve begins to lift at the desired and predetermined temperature. The thermostat may also be made up of inter-acting strips or plates, as

shown, which by their differing coeflicients of expansion perform the same function; or it will be understood that the thermostat may be of any known or suitable construction adapted to impart the desired movement to the valve rod I3.

The operation of the mechanism shown in Fig. 1 may be briefly described as follows:

When current is firstswitched on, the heating element 9 heats up the liquid until the temperature attained is that at which the thermostat I4 has been set to act. The thermostat I4 then by expansion causes the valve I2 to open to a certain extent and thus permits the ingress of cold water which mixing with the hot water causes cooling of the water surrounding the thermostat I4, thereby causing contraction of the bimetallic element and consequent closing of the valve I2. The cold water that has thus been permitted to enter the hot water tank lowers slightly the temperature of the water in the tank, but as the heating element 9 is in operation, the water is quickly heated up again until the temperature is such that the expansion of the bimetallic element again causes the valve I2 to operate and permit the entry of further water into the hot water tank 2.. This procedure continues until gradually the hot water tank is completely filled with hot water of the desired temperature for which the thermostat I4 has been set. Should the water then continue .to rise in temperature, the overtemperature thermostat II] will come into operation and automatically switch off the supply of current to the heating element 9, which supply will remain ofi unless the temperature of the water should fall below the predetermined figure when the thermostat I0 will switch on the electric current, whereby the temperature will again be raised to the desired degree.

Should hot water be drawn oif from the tank by means of the tap 8, cold water make-up will first flow out of the feed trough 4 through the feed pipe II into the hot water container 2, whereby the water surrounding the thermostat I4 will have a lower temperature, so aifecting this thermostat that it will close the valve I2 thereby preventing the entry of further cold make-up until the temperature of the water in the storage chamber has been brought up again, when the thermostat I4 will again open the valve I2 and the operation of the valve in this manner will continue until the tank 2 is again full of hot water at the desired temperature.

Although in the figure the thermostat I4 and the valve I2 controlled by the thermostat are shown at opposite ends of the tube II the valve can be placed in any suitable position other than that indicated. The thermostat I4 can be placed in any position suitable for its being appropriately aifected by the temperature of the water in the storage container.

Although in the above description it has been stated that the valve either opens or closes under the action of the thermostat the valve may be constructed so that it takes up a balanced position proportionate to the rating of the elements, and the temperature of the incoming water.

Referring now to the modified form of the invention shown in Fig. 2, a heater generally simi lar to that hereinbefore described in connection with Fig. 1 has the make-up controlling valve electrically actuated in response to the movements of the thermostat. In Fig. 2 and in the succeeding figures, parts similar to those described in connection with Fig. 1 are given the same reference numerals. As embodied, the valve II 2 is seated for vertical movement with respect to the angled inlet tube III as shown. The stem I9 of the valve extends upwardly from the valve seat through a tube or casing I20 and into a water-tight chamber I2I formed in the portion of the make-up trough 4 directly above the valve. The valve stem I9 constitutes the core of a sole- .noid I8 which is thus adapted to actuate the valve I I2 and control the movements thereof.

In accordance with this embodiment of the invention, the solenoid is electrically controlled by a thermostat II4 which is responsive to the temperature of the water in the heating chamber 2. Thermostat I I4 is maintained in a suitable casing H5 in the lower part of the heating tank 2 and thereby immersed in the heated water. The thermostat is adapted to control a switch in the enerheating element 9. When the temperature of the hot water falls below the predetermined limit, thermostat II4 will break the contact at I6 and the solenoid I will be de-energized. thereby closing valve II2 until the temperature of the water again has been raised sufllciently to re-actuate the thermostat. A sequence of operations, similar to that hereinbefore described in connection with the embodiment of Fig. 1, will then take place until-the tank is full of hot water within the predetermined temperature limits.

A further modification of the invention embodies the novel principle of controlling both the maximum temperature switch for the water heating current and the operation of the valve regulating the inflow of make-up water. As shown in Fig. 3, a single thermostat, responsive to the temperature of the heated body of water is adapted to open the make-up water valve at a predetermined minimum temperature and to open the heating circuit when the water temperature rises to the predetermined maximum. As embodied, two electric heating units 209 are mounted at the bottom of the tank 2 and between them a thermostat 2I4 which, through rod 2I3, actuates the make-up water valve 2I2. The rod 2I3 is extended above the valve and into the switch box 200 on the top of the cistern I. A switch, comprising the bridge piece 20I, formed at the upper end of rod 2I3, and two upwardly-urged spring contacts 202 are mounted in the switch box. The switch 20I-202 controls the circuit 203 for the heating unit 209.

In the operation of this device, the valve 2I2 and the circuit 203 will remain closed until the temperature of the water in tank 2 rises above the predetermined minimum. When the temperature has reached this minimum limit, the valve 2I2 will open and makeup water will be admitted to the tank in proximity to the heating units 209 and thermostat 2I4. The heating circuit however remains closed, because the spring contacts 202 follow the bridge 20 to some extent in its upward movement. When sufiicient makeup water has been admitted to the heating tank to lower the temperature, valve 2I2 will again close and this sequence of operations will be repeated until the tank 2 is filled with hot water, all without interrupting the flow of current to heating units 209.

When the temperature of the water finally reaches the predetermined maximum, the thermostat 2I4 will be deflected sufiiciently to raise bridge 20 beyond the limit of movement of the spring contacts 202 and the supply of current to the heating elements will thereby be cut off and will remain off until radiation losses or other causes lower the temperature of the stored hot water sufliciently to cause a closing of the switch.

In all of the hereinbefore described heaters, a vent pipe I00 may be provided between the top of tank 2 and the space above the level of the tank 4. A further modification is shown in Fig. 4, wherein the heating and control devices operate generally similarly to those shown and described in connection with Figure 1, but wherein the separate tank or trough for the cold make-up water is dispensed with. In this form, the currentsupply circuit 300 of heating unit 3 I9 is controlled by a maximum temperature thermostat 30I through a switching arrangement 302, which is generally similar in construction to that shown in Fig. 2 for controlling the solenoid.

The make-up water is admitted directly from the cold water main 5, the valve 305 being controlled by a minimum temperature thermostat 306 acting through a sliding rod 301 and a bell crank lever 308. The valve 305 is independent of and in series with the float-controlled valve 5.,

In operation, assuming the tank 2 to be only partially filled; the switch 302 closed; the float lever b in its lowermost position as shown; and the valve 305 controlled by the thermostat 306; the sequence of operations is the same as that in the heater shown in Fig. 3, so long as the tank is only partially fllled. However, when the level of the water in tank 2 nears the top of the tank, the float lever 5b will begin to rise and will ultimately close the valve 5 and thus prevent further entrance of make-up. Then the heating of the water will continue until the temperature has risen sufliciently to cause the over-temperature thermostat 30I to open the switch and cut oif the current to the heating element.

The invention in its broader aspects is not limited to the specific steps and mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages.

What we claim is:-

1. A mechanism for heating water including in combination a container for a body of. water, means for drawing off water at a predetermined level near the bottom of said container, heating means acting on the water below said predetermined level, a feed water reservoir supplying water to said chamber by gravity, a valve at said reservoir, a thermostat in, said container below said predetermined level, and connections from said thermostat to said valve for controlling the admission of water from said reservoir to said container, and separate thermostatic means for controlling the heating means.

2. A mechanism for heating water including in combination a container for a. body of water, means for drawing off water at a predetermined level near the bottom of. said container, heating means acting on the water below said predetermined level, a feed water supply for said container, a valve in said supply for admitting feed 7 water to the container, a thermostat in said container below said predetermined level, anJi fifitric circuit controlled by said thermostat, andvan electromagnet in said circuit, and connected to control said valve andn-separate thermostatic means for controlling the heating meansz- 3. A mechanism for heating water including in combination a container for a body of water, means for drawing off water at a predetermined level near the bottom of the container, electric heating means acting on the water below said predetermined level, a feed water supply, thermostatic means in the chamber below said predetermined level for controlling the heating means circuit, and valve means for regulating admission of feed water to the container, and thermostatic means controlling said valve means, the valvecontrolling thermostat being conditioned to open and shut the valve at temperatures lying within the range of the circuit-opening and closing temperatures of the heater thermostat.

4. A mechanism for heating water including in combination a container for a body of water, means for drawing off water at a predetermined level near the bottom of the container, electric heating means acting on the water below said predetermined level, a feed water supply, and thermostatic means located in the lower part of the container for controlling the action of said heating means and for electromagnetically controlling the admission of water from said supply means, the thermostatic control of the water supply being adapted to admit and shut off feed water to the container at temperatures lying within the range of the circuit-opening and closing temperatures of the heater thermostat.

ERNEST WHITBY.

IVOR AUGUSTUS DURANT PEDLER. ERNEST JOSEPH SELSTON. ARTHUR JOSEPH NEWMAN. ILEWEILYN ROLLS LESTER.

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