US3665156A - Heating-element protector for electric water-heater - Google Patents

Abstract

A device for preventing electrical energy flow to a water heating element when an insufficient amount of water is in contact with the element for absorbing the heat generated. The device or element protector is coupled to an exit pipe which extends into the heating tank immediately above the heating element. Normally open contact switches within the protector allow electrical energy flow to the element only when water covers the element and has entered the protector causing a diaphragm and a movable structure to force the switches closed. A helical spring and snap disc are employed to allow the switches to close and open at different pressure points. Means are provided to adjust the spring for different operating pressures. A float and chamber within the protector prevent switch activation when water does not cover the heating element.

Description

United States Patent Lee [ 1 May 23,1972

Primary Examiner-R. F. Staubly Attomey-Woodard, Weikart, Emhardt & Naughton [72] Inventor: Herbert P. Lee, 7490 N. Pennsylvania St.,

Indianapolis, Ind. 46240 57 ABSTRACT Filed: l 1970 A device for preventing electrical energy flow to a water heat- 1 N 7 240 ing element when an insufficient amount of water is in contact [2 1 with the element for absorbing the heat generated. The device or element protector is coupled to an exit pipe which extends [52] US. Cl. ..219/333, 137/202, 200/83 R, into the heating tank immediately above the heating element. 219/322, 219/332, 219/496 Normally open contact switches within the protector allow [51] Int. Cl. ..H05b 1/02 electrical n rgy flo t0 he elem n nly when water covers [58] Field of Search... ..137/202; 200/81 R, 83 R; the element and has entered the Protector causing a 219/3Q9 322424 332 333 49 diaphragm and a movable structure to force the switches closed. A helical spring and snap disc are employed to allow [56] References Cited the switches to close and open at difierent pressure points. Means are provided to adjust the spring for difierent operating UNITED STATES PATENTS pressures. A float and chamber within the protector prevent switch activation when water does not cover the heating ele- 542,516 7/1895 Brooks ..137/202 mam 1,119,980 12/1914 Mulligan.. ..137/202 X 2,591,852 4/1952 Murray ..2l9/332 8Clai|m,4Drawing Figures w* as a; I 57s e a s 90 93 92 /03 02Li Y 97 52qh 95 2 rQS V rfi/ 37 Patented May 23, 1972 3,665,156

2 Sheets-Sheet l 220v I 62 24 43 i INVEIN'IOR 7 #528627 55 BY mm/wmuumuma 02%;

AT TORNEYS Patented May 23, 1972 3,665,156

2 Sheets-Sheet 2 Fig. 3.

INVENTQR A i/ea er P [66 ATTORNEYS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an element protector.

2. Description of the Prior Art In the typical electric water heater, a heating element is immersed in the tank in order to heat the water to a predetermined temperature. Electrical energy is supplied to the element, with the internal resistance of the element resulting in the production of heat. The element is particularly susceptible to damage in the-event that an insufficient amount of water is in contact with the element to absorb the heat generated. In many cases, this will result in complete destruction of the element.

An electric water heater is installed in a new building generally before the building is complete and before the main electricity and main water are provided. Nevertheless, the installer will connect the heater to the electric power lines and the input water pipe. Subsequent to this installation, the main electricity may be turned on prior to the main water supply. Thus, the heating element will be destroyed since water heater tank does not contain water.

It is therefore desirable to prevent electrical energy flow to the element when an insufficient amount of water is in contact with the element. On the other hand, the element protector should not interrupt the flow of the electrical energy as a result of variations in the water pressure when there is sufficient water to absorb the heat from the element.

SUMMARY OF THE INVENTION heating tankimmediately above the heating element. Normally open contact switches within the protector allow electrical energy to flow to the element only when water covers the element and has entered the protector causing a diaphragm and a movable structure to force the switches closed. A float and chamber within the protector prevent activation of the switches when water does not cover the element. A helical spring and snap disc are employed to allow the switches to close and open at different pressure points. An adjustment screw is provided for changing the pressure points at which the switches open and close.

It is an object of the present invention to provide a device for preventing the flow of electrical energy to a heating element within a water heater tank when insufficient water exists within the tank to absorb the heat generated by the element.

It is another object of the present invention to provide a reliable element protector which may be easily attached to a water heater.

Yet another object of the present invention is to provide an element protector which will not interrupt the electrical energy flow as a result of pressure variations when sufficient water exists within the tank to absorb the heat generated by the element.

Related objects and advantages will be evident from the following description and drawing.

BRIEF DESCRIPTION OF THE DRAWING tector shown in FIG. 1.

FIG. 3 is a sectional view of the element protector taken along the line 3-3 and viewed in the direction of the arrows in FIG. 2.

FIG. 4 is an electrical schematic representation of the element protector connected between the source of electrical energy and the heater element.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to FIG. 1, there is illustrated a conventionalelectric water heater 10 having anouter tank 10 supported bylegs 11. Aninner tank 12 is located within outer tank 10' being surrounded on all sides by insulatingmaterial 13 for reducing or preventing heat transfer betweentank 12 and the outer environment.

Tank 12 has an outlet near its bottom connected tofaucet 14 which is mounted to outer tank 10' for draining purposes. Cold water from a main water supply, not shown, enterstank 12 throughinlet pipe 15 secured and sealed toouter tank 10 byhousing 18. The heated water exits tank 12 throughoutlet pipe 16 secured and sealed to outer tank 10' byhousing 19. Of course,pipes 15 and 16 pass through openings in the top wall oftank 12 and are sealed thereto. Pipe 20 is threaded intohousing 19 and is threaded on its opposite end to a four-way coupling 17. A conventional pressure-temperature relief valve 21 is threaded on one of the outlets of coupling 17 for safety purposes whilepipe 22 is threaded on one of the other outlets of coupling 17 to route the hot water to various user locations. The fourth outlet of coupling 17 is threaded intothreads 42, shown in FIG. 3, of waterheater element protector 23.

The water withintank 12 is heated to the desired temperature by aheater element 24 havingterminals 25 and 26 mounted to the outside surface oftank 10 for receiving electrical energy.Element 24 is located withintank 12 and is immersed in the water. 220 volt AC is used to power the heater element, shown in FIG. 2, and is routed throughfuses 29 and 30, throughelement protector 23 and finally toelement terminals 25 and 26. Of course, electrical connectors may be used at strategic locations to facilitate any wiring connections required between the terminals, element protector and the power source.

FIG. 2 is an enlarged perspective view of theelement protector 23 shown in FIG. 1. A sectional view of the element protector taken along thelines 33 in the direction of the arrows is shown in FIG. 3.Element protector 23 is a combination electrical and hydraulic assembly. The electrical mechanism is housed incontainer 31 which has alid 33 fastened to its top byscrews 34 andnuts 35.Captive nuts 35 may be secured around the top inside surface of the container wall in order to allow the fastening ofscrews 34 from the outside of the container.Hydraulic assembly 32 is fastened by itscircular flange 36 toflat portion 38 extending around the bottom ofcontainer 31 byscrews 39 andnuts 40.Diaphragm 37, having an outside diameter approximately equal to the outside diameter ofcontainer 31 andassembly 32 at itscircular flange 36, is fastened between the container and hydraulic assembly. Holes are provided indiaphragm 37 to allowscrews 39 to pass through.Screws 39 are tightened sufficiently so as to insure a water tight seal betweendiaphragm 37 andflange 36. This seal must extend around the top periphery ofchamber 53 thereby preventing escape of pressure within the chamber to be described later in this description.

A waterfloatable sphere 47 is located in float chamber 46 which is formed withinhydraulic assembly 32 by supportingmember 27 and mounting 41. Hexagonal shapedflanges 51 and 43 are formed respectively onmember 27 and mounting 41 in order to provide Wrench grasping surfaces for tightening the threads of mounting 41 to the threads ofmember 27 as shown atpoint 44. A water sealant may be placed in these threads to prevent water from leaking out through the threads from float chamber 46. A passageway ortube 45 connects float chamber 46 with coupling 17.Element protector 23 is threaded onto one of the outlets of coupling 17 bythreads 42 provided in mounting 41. The hexagonal shapedflange 43 may be grasped with a wrench in order to tighten the element protector to the coupling.

Thetop portion 28 of float chamber 46 is dome-shaped having anair tube 49 connecting the top portion of chamber 46 with the outside environment throughopening 49.Tube 50 connects float chamber 46 withchamber 53 and enters the dome-shapedportion 28 of float chamber 46 at a point slightly above thevertical side wall 54. The functions oftubes 45, 49 and 50 will be explained in the operation section of this specification. An O-ring 48 is fastened by adhesives or other means around the opening oftube 49 intotop portion 28 and provides a sealing seat forsphere 47 when the sphere floats to the top of chamber 46.

Container 31 houses switchbox 57 which has two normally open electricalcontact switches 55 and 56.Contacts 62 and 65 are provided onswitch 56 andcontacts 63 and 64 are provided onswitch 55. Each contact is connected to a separateterminal screw 59 in order that a separate input and output terminal willbe provided for each switch.Box 57 rests on upraised portion 58 ofcontainer 31 and is fastened by the fourterminal screws 59 todiscs 60 and 61. Terminal screws 59 are securely fastened tobox 57 in order to prevent rotation of the screws whennuts 66 are tightened thereon.Lock washers 67 1 cal energy sincescrews 59 are used simultaneously as fastening devices and as electrical terminals.Screws 68 are threaded through the wall ofcontainer 31 immediately above disc 61 and abuttingly rest on the top surface of disc 61 thereby preventingbox 57 from moving upwardly.Insulated wires 69, 70, 71 and 72 are respectively connected to the fourterminal screws 59 and are secured thereon betweennuts 66 and 73.Wires 69 through 72 are then routed throughlid 33 connectingheater element 24 with the source of electrical energy as previously described. An electrical schematic representation of the element protector is shown in FIG. 4 and will be described in the operation section of this specification. Twowire holders 74 and 75 are threaded in the top wall oflid 33 and respectivelysecure wires 69, 70, and 71, 72.

As may be seen from FIG. 2,tube 76 extends throughlid 33 down todiscs 61 and 60. A cutaway view oftube 76 is shown in FIG. 3.Tube 76 extends through disc 61 and rests on the top surface ofdisc 60.Flange 81 is formed around the bottom edge oftube 76 completely surrounding the tube and fits into a complimentary recess formed in the bottom surface of disc 61.Helical spring 80 is housed intube 76 abuttingly engaging the bottom ofspacer 79 and the top offlange 82 ofmovable element 83. Anadjustment screw 77 is threaded through the top wall oftube 76 having a blunt end for forcingspacer 79 againstspring 80.Screw 77 may be turned to increase or decrease the space within which spring 80 is located and thereby changing the force which spring 80 applies to flange 82.Nut 78 is positioned between the head ofscrew 77 and the top wall oftube 76 for locking the adjustment screw. The nut should be tightened against the top wall oftube 76 in order to lockscrew 77 in place.Movable element 83 has a shank 84 for fitting withinspring 80 insuring proper seating of the spring onflange 82. In addition,element 83 has a finger 85 which extends through an opening indisc 60 abutting against a concave orconvex snap disc 86. The snap disc is made from tempered steel plate and is secured to switchbox 57 by means of a wedge-shaped groove 87 extending around theopening 88 inbox 57. The outer edge ofsnap disc 86 is located within groove 87 allowing the disc to snap from one position to another when force is applied. The disc has two positions which are the open position, illustrated and shown by line 0, and the closed position, illustrated and shown by dashed lineC. Metal ring 89 is fastened by adhesives or other means to the bottom ofdisc 60 surrounding finger 85 and being located in opening 88.Ring 89 preventsdisc 86 from dislodging from groove 87 when it is snapped to the upper positionC. Domeshaped cylinder 90 is located between the twomovable arms 99 and 100 ofelectrical switches 56 and 55 and has a rod 91 extending out from the cylinder sides adjacent the movable switch arms. Rod 91 of electrically non-conductive material is located immediately below each movable arm in such manner as to forceswitch arms 99 and 100 upwardly as cylinder moves in the direction ofarrow 92.Contact 65 will close andtouch contact 62 asmovable arm 99 moves upwardly. Likewise, contact 63 will close andtouch contact 64 asmovable arm 100 moves upwardly. The dome-shaped portion ofcylinder 90 rests against the bottom center ofsnap disc 86. The bottom ofcylinder 90 has a recess for receivingfinger 94 ofmovable member 95 wherebycylinder 90 andmember 95 form a movable structure. Anopening 96 is provided in the bottom ofbox 57 allowingcylinder 90 andfinger 94 to slide within. The upraised bottom portion 58 ofcontainer 31 has an opening for allowingfinger 94 to slide in the direction ofarrows 92 or 93. Acircular base 98 is integrally connected to the bottom offinger 94 and rests on the top surface ofdiaphragm 37.Member 95 fits within upper chamber 52 fonned betweendiaphragm 37 and upper edge portion 58. Chamber 52 is circular, as viewed looking in the direction ofarrow 92, with an upperflat wall 102 having a diameter greater than the diameter ofbase 98.Flat portion 38 extends around chamber 52 being integrally connected to wall 102 by annularsloping wall 103. Likewise,chamber 53 is formed betweendiaphragm 37OPERATION Element protector 23 prevents electrical energy from flowing toheater element 24 when insufiicient water exists within the water heater to force water out throughexit pipe 16 for movingmember 95 upwardly. Thus, damage to the heater element is prevented which could otherwise occur as a result of insufficient water being within the tank to absorb the heat generated by the element.

FIG. 4 shows an electrical schematic of the element protector connected between the element and source of power. 220 volts alternating current is connected throughfuses 29 and 30 across contacts 62-65 ofprotector 23 toheater element 24 viaterminals 25 and 26. Electrical energy is prevented from flowing throughheater element 24 when the contacts of theelement protector 23 are in the open position. When the contacts of the element protector are in the closed position, contact 65 mates withcontact 62 andcontact 63 mates withcontact 64 thus, allowing the electrical energy to flow from the 220 volt AC power source to the heater element. The closing and opening of the contacts is controlled by water moving into and out ofchamber 53.

FIG. 3 shows the condition when the water heater does not contain sufficient water withintank 12 so as to force water out throughexit pipe 16. Therefore,sphere 47 rests on the bottom of chamber 46 andmember 95 rests on top ofdiaphragm 37. In addition, the electrical switches are in the normally open position and electrical energy is prevented from flowing to the heater element. As water enterstank 12 viapipe 15, the water level intank 12 will gradually rise. Eventually, water will exitpipe 16, passing through coupling 17 and intotube 45. Chamber 46 will then fill withwater forcing sphere 47 in the direction ofarrow 92 until the sphere seats on O-ring 48 thereby sealingtube 49 from chamber 46. Pressure will then be applied tomember 95 in the direction ofarrow 92 only when water has exitedtank 12 forcingsphere 47 against 0- ring 48. Air pressure will escape outtube 49 without applying force tomember 95 unless water has coveredelement 24 and has entered chamber 46 forcingsphere 47 to seat on the O ring. Therefore, to insure that the protector will activate only afterelement 24 is beneath the tank water level line, theexit pipe 16 should extend down to a point near the top ofelement 24. As the water pressure within chamber 46 increases, the water will move in the direction ofarrow 92 throughtube 50 and intochamber 53. Eventually, the pressure inchamber 53 will be sufiiciently great so as to forcediaphragm 37 andmember 95 in the direction ofarrow 92 and thereby forcingcylinder 90 and rod 91 upwardly, closing contacts 62-65 and 'As an example of one embodiment of the element protector, let us assume thatspring 80 exerts 6 pounds of force onelement 83 regardless of the position ofdisc 86. Let us further assume thatdisc 86 will snap from one position to another position when 4 pounds of force are applied to the disc. Thus,disc 86 will snap from the 0 position to the C position whencylinder 90 applies at least 10 pounds of force, 6 pounds to overcome the force exerted byspring 80 and 4 pounds of force to overcome the internal resistance ofdisc 86, to the bottom of thedisc 86 in the direction ofarrow 92. Likewise,disc 86 will snap from the C position to the 0 position whencylinder 90 applies 2 pounds of force or less to the bottom of the disc sincespring 80 viaelement 83 will apply 6 pounds of force in the direction ofarrow 93 to the top of the disc overcoming the internal disc resistance of 4 pounds. Further let us assume thattank 12 is empty. Thus, insufiicient pressure will exist inchamber 46 and 53 to forcemember 95 in the direction ofarrow 92 anddisc 86 will be in the 0 position as shown in FIG. 3. In addition,contact 65 will not be touchingcontact 62, and contact 63 will not be touchingcontact 64 thus preventing flow of electrical energy toheater element 24.

As water enterstank 12 viapipe 15, the water level within the tank will increase until eventually theheater element 24 is immersed in water. As water is added totank 12, water will eventually exitpipe 16 and enter coupling 17. Further increases in the water pressure withintank 12 will force water to enter chamber 46 ofprotector 23 viatube 45.Sphere 47 will float to the top of chamber 46 as the water level within the chamber increases.Tube 49 is provided to allow any trapped air to escape.Tube 49 will be sealed from the chamber when the water level within the chamber is sufficient to forcesphere 47 to seat on O-ring 48. Further increases in the pressure withintank 12 will force water uptube 50 and intochamber 53.Member 95 rests ondiaphragm 37 havingfinger 94 fitting into the bottom ofcylinder 90. Of course, the top portion ofcylinder 90 abutsdisc 86 which has finger 85 ofelement 83 resting on its top surface. As previously mentioned, rod 91 extends throughcylinder 90 at a point immediately below'the two arms ofelectrical switches 55 and 56. In the present example,disc 86 will snap from the 0 position to the C position when at least 10 pounds of force is applied to the bottom of the disc. Thus, if the area ofdiaphragm 37 exposed tochamber 53 is 1 square inch, for example, when the pressure withinlower valve chamber 53 equals or exceeds 10 pounds per square inch,diaphragm 37 andmember 95 will move in the direction ofarrow 92 forcingcylinder 90 to snapdisc 86 from the O to the C position. As cylinder90 moves in the direction ofarrow 92, rod 91 abuttingmovable arms 99 and I00 will force the arms upwardly thus forcingcontact 65 to touchcontact 62 andcontact 63 to touchcontact 64. Electrical energy is thus routed through the contacts from the power source to the heater element.

Electrical switches 55 and 56 will stay in the closed position until the pressure withinchamber 53 is less than or equals 2 pounds per square inch. Thus, electrical energy will be provided to the heater element and will not be interrupted as a result of variations of pressure withintank 12 unless the pressure decreases to the point when the pressure withinchamber 53 is less than or equals 2 pounds per square inch.Spring 80 will apply sufficient force viaelement 83 todisc 86 forcing the disc to the 0 position and also forcingcylinder 90 to move in the direction ofarrow 93 when the pressure withinchamber 53 equals or is less than 2 pounds per square inch. In addition, as cylinder'90 moves in the direction ofarrow 93, switches 55 and 56 will revert to their nonnally open positions witharms 99 and 100 moving downwardly providing forelectrical contacts 62 through 65 to assume an open position interrupting the flow of electrical energy toheater element 24.

Many variations in the above described structure are contemplated within the scope of the present invention. For example, a variety ofdifferent discs 86 and springs 80 may be used requiring different levels of pressure to force the disc or spring from one position to another position. Of course, spring will apply a different amount of force toelement 83 depending upon the space within which the spring is contained.Spring 80 will apply a force greater than 6 pounds ifspacer 79 is adjusted downwardly byscrew 77. Likewise,spring 80 will apply less than 6 pounds ifscrew 77 is adjusted upwardly allowingspacer 79 to move up.Protector 23 may be used in a variety of locations on water heaters, as long as it is above the heater element.

It will be evident from the above description that the present invention provides an apparatus for preventing the flow of electrical energy to a heater element within a water heater when insufficient water is in contact with the heater element to absorb the heat generated by the element. It will be further evident from the above description that the present invention provides a reliable heater element protector which may be easily attached to a water heater. The description and drawings herein should be considered as illustrative and not restrictive as variations can be made within the scope of the invention.

The invention claimed is: i

1. Protector apparatus for the electric heater element of a liquid storage and heating tank and comprising:

a closed liquid storage tank having an electric heating element therein and having an inlet for flowing water under pressure thereinto;

mounting means readily connectable to a liquid conduit fitting of said tank, said mounting means being located externally of said tank;

a float chamber on said mounting means and communicating with said fitting, said chamber having a vent to atmosphere and having a float therein operable upon flotation by liquid to close said vent, said chamber being disposed above the elevation of said element and receiving liquid from said tank only when said element is below the surface level of the liquid in said tank;

electric switch means on said mounting means and normally open during absence of pressure in said tank;

switch operator means coupled to said switch means and communicating with said chamber and operable in response to attainment of a predetermined moderate positive gauge pressure in said chamber to close said electric switch means.

2. The apparatus of claim 1 wherein:

said mounting means include pipe threads connectable to standard pipe fittings.

3. The apparatus of claim 1 wherein:

said switch operator means is operable in response to a predetermined positive gauge pressure in said chamber somewhat lower than said moderate pressure to open said electric switch means.

4. The apparatus ofclaim 3 wherein:

said switch operator means has a movable structure for operating said electric switch means, and a diaphragm supporting said structure and sealably covering a cavity connected to said chamber; and

said diaphragm receives pressure from said chamber via said cavity and transmits force to said movable structure to operate said electric switch means.

5. The apparatus of claim 4 and further comprising:

a spring on said mounting means; and

an element having a first and second given configuration being reversibly changeable from the one configuration to the other configuration by force.

6. The apparatus of claim 5 wherein:

said element changes configuration as a result of force applied from said movable structure and said spring, thereby allowing said movable structure to operate said electric switch means.

7. The apparatus of claim 6 and further comprising:

adjusting means for changing the force applied by said spring to said element.

8. The apparatus of claim 7 and further comprising:

a container for housing said electric switch means; a hydraulic assembly for housing said float chamber and float; I said diaphragm being fastened between said container and said hydraulic assembly.

Claims (8)

1. Protector apparatus for the electric heater element of a liquid storage and heating tank and comprising: a closed liquid storage tank having an electric heating element therein and having an inlet for flowing water under pressure thereinto; mounting means readily connectable to a liquid conduit fitting of said tank, said mounting means being located externally of said tank; a float chamber on said mounting means and communicating with said fitting, said chamber Having a vent to atmosphere and having a float therein operable upon flotation by liquid to close said vent, said chamber being disposed above the elevation of said element and receiving liquid from said tank only when said element is below the surface level of the liquid in said tank; electric switch means on said mounting means and normally open during absence of pressure in said tank; switch operator means coupled to said switch means and communicating with said chamber and operable in response to attainment of a predetermined moderate positive gauge pressure in said chamber to close said electric switch means.

2. The apparatus of claim 1 wherein: said mounting means include pipe threads connectable to standard pipe fittings.

3. The apparatus of claim 1 wherein: said switch operator means is operable in response to a predetermined positive gauge pressure in said chamber somewhat lower than said moderate pressure to open said electric switch means.

4. The apparatus of claim 3 wherein: said switch operator means has a movable structure for operating said electric switch means, and a diaphragm supporting said structure and sealably covering a cavity connected to said chamber; and said diaphragm receives pressure from said chamber via said cavity and transmits force to said movable structure to operate said electric switch means.

5. The apparatus of claim 4 and further comprising: a spring on said mounting means; and an element having a first and second given configuration being reversibly changeable from the one configuration to the other configuration by force.

6. The apparatus of claim 5 wherein: said element changes configuration as a result of force applied from said movable structure and said spring, thereby allowing said movable structure to operate said electric switch means.

7. The apparatus of claim 6 and further comprising: adjusting means for changing the force applied by said spring to said element.

8. The apparatus of claim 7 and further comprising: a container for housing said electric switch means; a hydraulic assembly for housing said float chamber and float; said diaphragm being fastened between said container and said hydraulic assembly.

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