US2387175A

US2387175A - Water heater control system

Info

Publication number: US2387175A
Application number: US516693A
Authority: US
Inventors: Clark M Osterheld
Original assignee: McGraw Electric Co
Current assignee: McGraw Electric Co
Priority date: 1944-01-01
Filing date: 1944-01-01
Publication date: 1945-10-16
Anticipated expiration: 1962-10-16

Description

Oct. 16, 1945.

C. M. OSTERHELD WATER HEATER CONTROL SYSTEM Filed Jan. 1, 1944 3 sheets sheet 1 [III] III/II INVENTOR. CLARK .05 ZERHZLD My 6 g ATTORNEY Oct. 16, 1945. c. M. OSTERHELD WATER HEATER CONTROL SYSTEM 5 Sheet-Sheet 2 Filed Jan. 1, 1944 I N V EN TOR. 62 AR%% OSTER/vfll? BY M I III ATTORNEY Oct. 16, 1945. c. M. OSTERHELD WATER HEATER CONTROL SYSTEM 3 Sheets-Sheet 5 Filed Jan. 1, 1944 CBC s IN V EN TOR. 62 A Gyms a D BY ATTORNEY .a control system for a water PatentedOct. 16, 1945 WATER HEATER CONTROL SYSTEM Clark M. Osterheld, Stoughton, Wis., assignor to MeGraw Electric Company, Elgln, lll., a corporation of Delaware Application January 1, 1944, Serial l do. 516,693

13 Claims.

My invention relates to water heaters and particularly to control systems for tank water heaters.

An object of my invention is to limit the maximum energy input into a tank.

Another object of my invention is to provide heater to effect selective energization of a plurality of heaters un-' der predetermined conditions of demand for hot water.

Another object of my invention is to provide a single heater control switch mountable on a tank and controlled jointly and simultaneously by temperature conditions of water throughout the tank.

Other objects of my invention will either be apparent from a, description of a control system embodying my invention or will be set forth in the course of such description and pointed out particularly in the appended claims.

In the drawings, t

Figure 1 is a verticalseotion of a water tank showing the electric circuits and contacts when the, water in the top and bottom of the tank is cold,

v Fig. 2 is a fragmentary sectional view taken on the line 2--2 of Fig. 1,

Fig. 3 is a fragmentary view showing the position of the contacts when the water in the upper part-oi the tank is hot,

Fig. 4 is a fragmentary view showing the position of the contacts when all of the water in the tank is hot,

Fig. 5 is a top plan view of the parts shown in Fig. '3,

Fig. 6 is a fragmentary end view of the parts shown in Fig. I,

Fig. '7 is a side elevational view of a pluralposition plural-contact heater-control switch,

Fig. 8 is 9, fragmentary sectional View similar to that of Fig. 1 showing a modified form'of device embodying my invention, and,

Fig. 9 is an enlarged view of a portion of Fig. 8.

The control system and method of control embodying my invention applies more particularly to domestic hot water tanks having an upper and a lower heater therefor,the main object of my invention being to so control the heaters that there shall always be at least a small quantity of hot water available for immediate use and that the maximum energy input to heat the water shall be definitely fixed. 1

I have shown a hot water tank It surrounded by heat insulation I3 and an outer casing therearound all in a manner well known in the art. The tank is provided with a lower cold water inlet pipe I! and an upper hot water outlet pipe I9 and I may provide also supports 23' all of which are now well known in the art.

I provide an upper electric heater 2! and a lower electric heater 21 each of which may be positioned around the tank and located in a-tunnel 29.

Referring first to Figs. 1 to 7 inclusive I have there shown a plural-contact plural-position heater control switch 3| adapted to be actuated by an upper thermally-expansible rod 33 and a lower thermally-expansible rod 35. The upper rod 33 has its upper end suitably fixedly secured as by a bracket 37 to the upper end of the tank while the lower rod 35 has its lower end fixedly secured to a bracket 38 which in turn is fixedly secured against the lower end portion of th tank H. The

brackets

31 and 39 are of high-heat conducting material and are secured in good heatreceiving relation to the tank. The heat-insulating material 23 is provided with an elongated recess ll for locating the two substantially c0- axially aligned

rods

33 and 35 which as will be noted from Fig. 1 of the drawings'are so mounted as to extend longitudinally of the tank ii and spaced therefrom. I may provide plates 43 of any suitable material spaced apart so as to prevent convection currents of air occurring in the elongated recess 8!. The two

rods

33 and 35 are made of a high expansion material such as alu- The linear temperature co-efllcient of expansion of aluminum is substantially twice that of the iron or steel .of which the usual domestic hot water tank is made.

The plural-contact plural-position switch 3| is I supported on pivot pin 49 in lugs 41. An adjusting screw 53 having a lock nut 55 thereon extends through the horizontalportion of arm 5i and is adapted to engage against the lower surface of upper rod 33. l

Frame 45 comprises a vertically upwardly-extending portion 5! having a. pair of lugs 59 ex tending therefrom toward the tank and an arm 6i is supportfid on lugs 5% as by a pivot pin 63. The lower end of arm Si is pivotally connected with a horizontal arm the right hand end portion of which is adapted to move horizontally in a pair of supporting and guiding stirrups 61 and 58 which are connected to or a part of a pair of spaced horizontal portions 69 of frame $5. The

' upper endof arm 5i is rounded and adapted to The upper end portion of member 57 has secured thereon a pair of contacts H, a block 13 of electric-insulating material being provided to suitably insulate them from frame 35; A first two-part arm 75 is pivotally supported at its lower end adjacent the inner end 'of parts 69 and has insulatedly mounted thereon at its upper end a contact bridging member H. An over center spring 19 has its upper end connected to a pivot pin on arm 15, the lower end of spring 19 being suitably secured to a vertically upwardly-extending lug 8| on arm 65.

A second swinging arm 83 is pivotally mounted adjacent the outer end portion of member 69 and has insulatedly mounted thereon at its upper end a pair of contact members 85, of L-shape. An over center spring 81 has its upper end pivotally connected to the, upper end portion of arm 83 while its lower end is connected to a lug 89 constituting'a part ofor secured to arm 65.

A stop member for the two arms and 83 includes a horizontally-extending member 9i having an inner stop lug 9S and an outer stop lug 95 thereon adapted to be engaged by the

arms

15 and 83. Reference to Fig. 7 will show that the center line of coil spring 19 is closer to the pivot Point of arm 15 than is the center line of spring 81 from the pivot point of arm 83. This has "the result that arm 15 will be caused to move over against stop lug 93 with a snap action upon movement of arm 65 in a right hand direction, without affecting the second arm. 83. Further assure these conditions the design, constructionand adhave used the 'words "hot water" hereinafter I refer to water which may have a temperature on the order of say 150 F. For simplicity it may be assumed that the temperature of the cold water is the usual normal room temperature, namely 70 F. The length of the

rods

33 and 35 will also be a minimum since they also will have a temperature of substantially 70 F. Under Justment of the

expansion rods

33 and 35 and of the plural-contact plural-position heater control switch 3! is such that the parts thereof will be in the positions shown particularly in Fig. 7 of the drawings, from which it will-be noted that the contact bridging member 11 is in engagement with the contacts H so that the upper heater alone is energized. This will result in heating up of a relatively small amount of water in the top portion of the tank with the result that the temperature of the bracket 3'! will be raised from substantially 70 F. to substantially 150 F. with the result that the upper expansion rod 33 will. V have its length increased a greater amount than will occur in the length of the upper portion of the tank with the result that the lower end portion of rod 33 will cause downward movement of adjusting screw 53 with an attendant turning movement of arm 5| in a clockwise direction.

This will result in pressure against arm 6| to counteract thetendency of spring 91, with result ant turning movement of arm 61 in a counterclockwise direction and attendant movement of arm 65 toward the right, as seen in Fig. 7.' It

will be noted that the position of springs I9 and 81 are relatively different so that the right hand movement of arm 65 will cause swing movement movement of arm 65 in-a right hand direction will cause turning movement of the second arm 83 with a snap action against stop lug 95. Upon movement of arm 65 in a left hand direction, arm 83 will be causedto move first with arm I5 moving upon further movement of arm 65 ina left hand direction. Turning'movement-of arm l5 in a clockwise direction will cause deenergization of the upper heater 25 and energization of the lower heater 2! and turning movement of arm 83 in a clockwise direction will cause deenergization of the lower heater 21.

The arm 65 which is adapted to be moved in a straight line axially thereof is biased into its left hand limiting position by a spring 9?, and

a pair of rollers 98 are provided in portion to to permit of easy movement of bar 65.

I provide a bracket 99 which may be secured against the outside of the tank by screws iill extending into metallic blocks H33, heat-insu-= lating'material 905 being provided 'therebetween of arm 15 in a. clockwise direction before swinging movement of arm 83 will occur. This will cause engagement of contact bridging member 11 with the two contact terminals 85 with the result that the upper .heater 25 is 'deenergized but the lower heater 2! is energized. The diagram of connections is shownin Fig. 1, which shows twosupply circuit conductors W9 and 'l i i.

Heating oi the rest of the water in the tank H will continue until substantially all of the water in the tank is hot. When this occurs the temperature of bracket 39 will also be on the order of substantially 150 F. with the result that the temperature of the lower expansion rod 35 will also be on the order of 150 F. with consequent iii? to suitably heat-insulate the bracket 99 -fromi the temperature of the tank water. The bracket is provided with lateral extensions ltl at its upper and lower ends, having apertures therein to receive the

rods

33 and 35 to maintain them in alignment, it being understood that the rods may move longitudinally in the portions till.

Let it be assumed that the tank has been filled with cold Water, in which case the longitudinal dimension of the tank will be a minimum relative to its dimension afterwards when substantially all of the water in the tank has been heated to a predetermined temperature. Where I increase in length of expansion rod 35. I

The result of this expansion of rod 35h that arm at is caused to turn in a clockwise direction still further with resultant turning movement oi aunt! in a counter-clockwise direction and further right hand movement of' arm 65. When arm 68 has been moved against spring at suificlently so that the lower end of spring 31 has been moved beyond the pivot point of arm 33, the arm 83 will turn in a clockwise direction against stop so that the lower heater 2'! is deenergized by reason of the disengagement of contact terminals $5 from contact bridging member ll.

It is thus evident that the singleplural-contact plural-position switch is actuated jointly and simultaneously by the two

expansion rods

33 and 35 which, are subject to the thermal conditions of the water in the upper and in the lower parts of the tank so as to energize the upper heater only when all of the water in the tank is cold until such time as a partof the water in the upper-portion of the tank has been heated after which the upper heater is deenergized and the lower heater is energized until substantially all of the water in the tank is hot.

Referring now to Figs. 8 and 9 of the drawings I have there illustrated a modification ofthecontrol system shown inFigs. l to 7 and embodying my invention and have shown an upper rod H3 and a lower rod H secured fixedly respectively .at the uppe end of the upper rod against the upper end portion of the tank as by a bracket I I? and the lower end of the lower red as by a bracket H3. Rods H3 and iii are of non-expansible material or alloy such as Invar. The switch 3i is secured to the upper end portion of rod H5 as by a member 44 and an L-shaped lever arm III is pivotally mounted intermediate the horizontal part thereof on lugs I 23. The lower face of the upper rod H3 has secured thereto a depending lug I25 having pivotal engagement with the left hand end portion of the horizontal arm there will be a tendency for arm i2! to be turned in a clockwise direction with attendant move-v ment or arm Si in a counter-clockwise, direction and movement of arm 65 toward the right. When arm 65 and particularly spring 19 have, been moved sufliciently to the right so that the lower portion of spring 19 has been moved horizontally beyond the pivot point of arm (5, arm 15 will be moved in a clockwise direction, resulting in disengagement of bridging member 11 from contact terminal II with deenergization of the upper heaterr Contact bridging member 11 has been moved into electrical engagement with contact terminals 85 on arm 83 sorthat lower heater 21 in now energized.

When substantially all of the water in the tank has been heated to say 150 F., the entire length of tank H is such that arm i2l will have been turned sufficiently in clockwise direction to cause further sliding movement of arm 65 toward the right so that arm 83 will have been turned in a clockwise direction against stop 95 with the result of disengagement of terminals 85 from bridging member I1 and resultant deenergization of the lower heater 21. The arm 15 is prevented from following the arm 83 by contacting the stop 93.

If it be assumed that hot water is demanded and a relatively small amount is used, say about one-third of a tank full, arm 65 will be caused to move toward the left suffici'ently to cause swinging movement of arm 83 in a counter-clockwise direction to bring terminals 85 again in engagement with contact bridging member 11 whereby the lower heater 2! will again be energized, this energization continuing until substantially all of the water in the tank has again been heated to say 150 F. when bar 65 will be moved to the right to cause deenergization of the lower heater 21.

I am aware of other patents showing a very different control system for an upper and a lower tank heater comprising a control switch thermally actuated in accordance with the temperature of the water in the upper end portion of the tank and controlling not only the upper heater but also the lower heater. The lower heater is also provided with a thermally-actuable' switch. In contradistinction to this system I may point out that my improved system includes a single plural-contact plural-position switch and two rod members, one of which supports the switch, the two red members having their outer ends fixedly secured to end portions of the tank, the inner end portions' of the rods extending substantially closely toward each other, relative movement of the ends of said rods occurring as a consequence of the different thermal linear expansion of the two rods and of the tank when the tank is filled with cold water or filled with hot water,v

The device and system embodying my invention therefore provides a relatively simple control system and switch efiective for the desired purpose of limiting the energy input into a tank and of always maintaining available for immediate use at least a predetermined amount of hot water.

Various modifications may be made in the device and system embodying my invention and all modifications thereof coming clearly within the scope of the appended claims are to be considere a part thereof.

I claim as my invention:

I l. A water heater control system for a hot water tank having an upper and a lower electric heater for said tank, a single plural-contact plural-position switch for selectively controlling the energization of said heaters, an upper rod having its upper end secured fixedly to the upper end portion of said tank, a lower rod having its lower end secured fixedly to the lower end portion of said tank, said rods extending longitudinally of said tank with their inner ends spaced apart, and having difierent linear thermal expansion than said tank, means supporting said switch on the inner end of one of said rods and switchactuating means engaged by the inner end of the other rod for causing movement of said switch into a position to eilect deenergization of the lower heater and energization of said upper heater when the tank is substantially full of cold water.

2. A water heater control system for a hot water tank having an upper and a lower electric heater for said tank, a single plural-contact plural-position switch for selectively controlling the energization of said heaters, an upper rod having its upper end secured fixedly to the upper end portion of said tank, a lower rod having its lower end secured fixedly to the lower end portion of said tank, said rods extending longitudinally of said tank with their inner ends spaced apart, said rods having difierent linear thermal expansion than said tank, means supporting said switch on the inner end of one of said rods and switch-actuating means engaged by the inner end of the other rod for causing movement of said switch into a position to effect deenergization of the lower heater and energization of said upper heater when the tank is substantially full of cold water andto efiect deenergization of said upper heater and energization of said lower heater when the tank contains a predetermined quantity of hot water in the upper portion thereof.

3. A water heater control system for a hot water tank having an upper and a lower electric heater for said tank, a single plural-contact plural-position switch for selectively controlling the energization of said heaters, an upper rod having its upper end secured fixedly to the upper end portion of said tank, a lower rod having its lower end secured fixedly to the lower end portion of said tank, said rods extending longitudinally or said tank with their inner ends spaced apart and having different linear thermal expansion than said tank, means supporting said switch on the inner end of one of said rods and switch-actuating means engaged by the inner end of the other rod for causing movement or" said switch into a position to efiect deenergization of the lower heater and energization of said upper heater when the tank is substantially full of cold water and to eiiect deenergization of said upper heater and energlzation of'said lower heater when the tank contains a predetermined quantity of hot water in the upper portion thereof and to effect deenergization of said lower heater when the tank is substantially full of hot water.

i. A water heater control system for a hot water tank having an upper and a lower electric heater therefor, a single plural-contact three-position switch for selectively controlling said heaters, a pair of rods having different linear thermal expansion than said tank, the length of each rod being slightly less than one-half of the length of the tank, extending longitudinally of the tank with the outer ends fixedly secured to the end portions of the tank, said rods jointly controlling said being slightly less than one-half of the length of the tank, extending longitudinally of the tank with the outer ends fixedly secured to the end portions of the tank, said rods jointly controlling said switch in accordance with the temperature of the water throughout the tank to cause ener gization of the upper heater only, when the tank is full of cold water and to cause deenergization of the upper heater and energization of the lower heater when a predetermined part of the water in the tank has been heated-to a predetermined temperature.

6. A water heater control system for a hot water tank having an upper and a lower electric heater therefor, a single plural-contact threep0- sition switch for selectively controlling said heaters, a pair of rods having different linear thermal expansion than said tank, the length of each rod being slightly less than one-half of the length of the tank, extending longitudinally of the tank with the outer ends fixedly secured to the end portions of the tank, said rods jointly controlling said switch in accordance with the temperature of the water throughout the tank to cause energization of the upper heater only when the tank is full of cold water and to cause deenergization of the upper heater and energization of the lower heater when a predetermined part of the Water in the tank has been heated to a predetermined tembeing slightly less than one-half o1" the length of the. tank, extending longitudinally of the tank with the outer ends fixedly secured to the end portions of the tank, said rod jointly controlling said switch in accordance with the temperature of the water throughout the tank to cause energize.- tion of. the upper heater only when the tank is full of cold water and to cause deenergization of the upper heater and energization of the lower heater when a predetermined part of the water in the tank has been heated to a predetermined temperature and to cause deenergization of the lower heater when substantially all of the water in the tank has been heated to a predetermined temperature and to cause reenergization of said lower heater in case of withdrawal of a predetermined relatively small amount of hot water from the tank. 1.

8. A water heater control system for a hot water tank having an upper and a lower electric v heater therefor, a single plural-contact three-position switch for selectively controlling said heaters, a pair 02 rods having diiierent linear thermal expansion than said tank, the length of each rod being slightly less than one-half of the length.

of the tank, extending longitudinally of the tank with the outer ends fixedly secured to the end portions of the tank, said rods jointly controlling said switch in accordance with the temmrature of the water throughoutthe tank to cause energization of the upper heater only when the tank is full of cold water and to cause deenergization of the upper heater and energization of the lower heater when a predetermined part of the water in the tank has been heated toa predetermined temperature and to cause deenergization of the lower heater when substantially all of thewater in the tank has been heated to a predetermined temperature and to cause reenergization of said upper heater only in case of withdrawal of a predetermined relatively large amount of hot water from the tank.

9. A water heater control system for a bottleter tank, having a cold water inlet at its lower end and a hot water outlet at its upper end and an upper and a lower electric heater, comprisperature and to cause deenergiz'ation of the lower heater when substantially all of the water in the tank ha been heated to a predetermined tem-= perature.

7. A water heater control system for a hotwater-tank having an upper and a lower electric ers, a pair of rods having. difierent linear thermal expansion than said tank, the length or each rod heater therefor, a single plural-contact three-po v sition switch for selectively controlling said heating a single plural-contact three-position switch for selectively controlling said heaters and means for'actuating said switch comprising an upper rod having its upper end fixedly secured to the upper end of the tank, a lower rod having its lower end fixedly secured to the lower end of the tank, said rods extending longitudinally of said tank with their inner ends spaced apart, said rods having a linear thermal expansion difierent than that of the tank, means supporting said switch on the inner end of one of said rods and switch-actuating means engaged by the inner end of the other rod for causin movement of said switch into a position to eficct energization of said upper heater only when the tank is substantially full of cold water. I

10. A water heater control system for a hot water tank having a cold water inlet at its lower end and a hot water outlet at its upper end and an. upper and a lower electric heater, comprising a single-plural-contact three-position switch for selectively controlling said heaters and means for actuating said switch comprising an upper rod having its upper end fixedly secured to the upper end of the tank, a lower rod having its lower end fixedly secured to the lower'end of the tank, said rods extending longitudinally of said tank with their inner ends spacedapart, said rods having a linear thermal expansion difierent than that i; i l

of cold water and to cause deenergization of the upper heater and energization of the lower heater when a predetermined part of the water. in the tank has been heated toa predetermined temperature.

11. A water heater control system for a hot water tank having a cold water inlet at its lower assigns end and a hot water outlet at its upper end and an upper and a lower electric heater, comprising a single plural-contact three-position switch for selectively controlling said heaters and means for actuating said switch comprising an upper rod having its upper end fixedly secured to the upper end of the tank, a lower rod having its lower end fixedly secured, to the lower end 01 the tank, said rods extending longitudinally of saidfltank with their inner ends spaced apart, said rods having a linear thermal expansion greater than that of the tank, means supporting said switch on the inner end of one of said rods and switch actuating means engaged by the inner end or the other rod for causing movement of said switch into a position to eflect energization of said upper heater only when the tank is substantially full of cold-water and to cause deenergization of the upper heater and 'energization of the lower heater when a predetermined part of the water in the tank has been heated to a predetermined temperature and to cause deenergization of the lower heater when substantially all of the water in the tank has been heated to a predetermined temperature.

12. A water heater control system for a hot water tank having a cold water inlet at its lower end and a hot water outlet at its upper end and actuating said switch comprising an upper rod having its upper end fixedly secured to the upper end of the tank, a lower rod having its lower end fixedly secured to the lower end of the tank,

said rods. extending longitudinally oi said tank with their inner ends spaced apart, said rods having a linear thermal expansion less than that of the tank, means supporting said switch on the inner end of one 01' said rods and switch-actuating means engaged by the inner end of the other rod for causing movement of said switch into a position to eflect energization of said upper heater only when the tank is substantially full of cold water and to cause deenergization of the upper heater and energization of the lower heater when a predetermined part of the water in the tank has been heated to a predetermined temperature and to cause deenergization or the lower heater when substantially all of the water in the tank has been heated to a predetermined temperature and to cause reenergization of said lower heater in case of withdrawal of a predetermined relatively small amount of hot water from the tank.

13. A water heater controlsystem for a hot water tank having a cold water inlet at its lower end and a hot water outlet at its upper end and an upper and a lower electric heater, comprising a single plural-contact three-position switch for selectively controlling said heaters and means for actuating said switch comprising an upper rod having its upper end fixedly secured to the upper end of the tank, a lower rod having its lower end fixedly secured to the lower end of the tank, said rods extending longitudinally of said tank with their inner ends spaced apart, said rods having a linear thermal expansion greater than that of the tank, means supporting said switch on the inner end of the lower of, said rods and switchactuating means engaged by the inner end of the upper: rod for causing movement of said switch into a position to effect energization of said upper heater only when the tank is substantially full of cold water. i

' CLARK M. OS'I'ERHELD.