US1508982A - Electric water heater - Google Patents

Description

Sept. 16. 1924.

J. A. M DONALD ELECTRIC WATER HEATER Filed Sept. 28, 1922 INVENTE'JR.

Patented Sept. 16, 1924. I

UNITED STATES PATENT OFFICE.

ELECTRIC WATER HEATER.

Application filed September 28 1822. Serial 1T0. 591,062.

To all whom it may concern:

Be it known that 1, JAMES ALEXANDER MACDONALD, of the city of Brantford, county of Brant, Province of Ontario, Canada, a subject of the King of Great Britain, have invented certainnew and useful Improvements in Electric Water Heaters, of which the following is a specification.

This invention relates to heaters adapted for heating water, and particularly to that type used in heating water in domestic hot water boilers. The object of the invention is to devise a construction which is interchangeable so that it may be used in various Ways, as for example, by being inserted directly in the interior of a hot water boiler, or by being mounted singly or in sets in a separate casing mounted alongside the boiler.

I A further object is to devise a construction of heatin element by the use of which greater e ciency will be obtained for the amount of current used.

Another object is to so arrange the heating element in its housing that it may be removed, and replaced with a similar element or with an element of larger or smaller capacity without in any way interfering with the water connections of the boiler or casing, and to so arrange the connections that the connections outside the boiler or casing are insulated from the heat from the element, and also to so arrange the device that moisture from outside is prevented from working in to the interior of the element housing.

The above mentioned and other objects are attained by means of the constructions hereinafter described and illustrated in the accompanying drawings in which Fig. 1 is a longitudinal section of the improved heater as mounted ori the interior of a'domestic hot water boiler;

Fig. 2 a cross section through the heating element; and

Fig. 3 a cross section through the housing. In the drawings like numerals of reference indicate corresponding parts in the different figures.

1 is part of which is provided with the usual threaded opening in its side. 2 is the housing for the heater, which housing is preferably formed of brace tubing and has one closed the shell of a hot water boiler,

end. To the open end of the housin 2 is secured the sleeve 3, having a threade portion thereon adapted to fit the -threaded opening in the boiler 1.

On the end of this sleeve 3 is cast a band 4 preferably of aluminum, the sleeve being provided with grooves or recesses 5 in which the metal of theband is adapted to run to anchor the band on the sleeve. The wrench used for installing the device is applied to this band 4, and there is therefore no danger of distorting or damaging the housing 2 or sleeve 3 by the wrench. I

It will be noted on reference to the drawings that the exterior surface of the housing is provided With a series of corrugations 6, which corrugations may be formed as a spiral thread. These corrugations not only increase the heating area of the housing, but it is found'in practice that a housing provided with these corrugations is not nearly so liable to twist or warp, as a housing without these corrugations.

The heating element comprises a core or base 7, preferably of soapstone as this material possesses two important features not found in porcelain which has heretofore mainly been used for this purpose. One of these features is thatthe soapstone more rapidly absorbs and conducts heat from the resistance and the other feature is that it retains the heat fora considerable time once it has become saturated.

In this core 7 are formed, by machining, a plurality of longitudinal slits 8, and in these slits is wound the resistance winding 9. This resistance winding is formed as a ribbon and is set on edge in the slits.- At least sufiicient high temperature heat conducting dielectric cementis then placed in the slits to properly hretain the resistance winding in place. I on the setting of the cement has reached a certain point, the current is turned on the resistance winding and as it expands it forces back the cement sufliciently to always give the winding room for expansion. The winding is then at perfeet liberty to expand in the slits and there is therefore no dan er of the winding suffering from any un ue expansion strains.

To hold the resistance winding in place while the cement is being filled in the slits and setting, annular grooves 10 are formed in the core and in each of these grooves a thread is wound over the resistance windtemperature of the resistance winding and the higher temperature imparted to the core is thatthe heater operates With greater speed and efliciency and there is not-the danger of the winding burning out.

At one end of the core is formed, preferably integral therewith, the spacer 11 to hold the core spaced from the closed end of the housing-2. At the other end of the core preferably integral'therewith is formed the blockv 12 and in each side of this block is formed a groove 13. The ends of the resist.- ance winding 9 are led one into each of these grooves; v

Heretofore it has usually been the practice to provide suitable bolts and nuts for seto the leads. Due to temperature stresses and other cause sfthese bolts and nuts in 5. tightly with asbestos fibre 16. The outside and while doingso is preheated, and when it strikes the hot solid end of the soapstone core it is further preheated, and there is therefore no danger of moist air passing through into theinterior of the housing to I condense and drop on to the resistance winding, and there is thus also avoided the usual noise caused by condensation within the housing.

To prevent the heat from the device being conducted. to the connections outside the *tanks, washers 17 of asbestos or like material are placed between the ends of the sleeve 8 66 and band 4 and the end of the connector 18.

of sufiicient size for the passage of the wires 14. The connector 18 is secured in position by screws 19' passing through the washers 1'7 into the end of the band 4.

22 is a condulet the end of'whichis adapt- .seen that a compact and effective arrangelnent has been devised; that there is no ne- 'having a very long life.

curing the ends of the resistance winding v -of a core of refractory non-conducting maair passes very slowly through this packing,

These washers are provided with holes only wires 21.

From the construction described it will be cessity of removing the housing once it is in position; that the heating element is easily removed and replaced if necessary; that there is little danger of moist air working into the interior of the housing; that the outside connections are well heat insulated from the heating element; and finally that the method ,of mounting the winding on the core is one which will result'in the winding As stated in the preamble of the specification, it will be understood that the heater might be mounted in a separate casing from the water tank or that two or more heaters may be mounted in a single casing, and in the latter case the heaters will be so con-- nected'that one or more may be used as desired to give a'number of different heats.

What I claim as my invention is 1. In'an electric heater, the combination of a substantially solid cylindrical core of refractory nonconducting material having a plurality of narrow slits formedlongitudinally thereof; and a resistance element of lesser depth than and mounted in said slits, said resistance being held in the bottom of the slits by dielectric cement.

2. In-an electric heater, the combination terial having a plurality of slits formed longitudinally thereof; and a resistance element mounted in said slits, said slits being closed by dielectric cement, said element, being free to expand in said slits. 3. In an electric heater, the combination of a substantially solid cylindrical core of refractory non-conducting material having a plurality of narrow slits formed longitudinally thereof; and a ribbon resistance element of lesser width than the depth of the slits and set im edge in said' slits, said resistance being held in the bottom of the slits by dielectric cement. q

4. In an electric heater, the combination of a core of refractorynon-conductin material having a plurality of slits forme 1ongitudinally thereof; and a ribbon resistance element set on edge "in said slits, said slits being closed by dielectric cement, said ele ment being free to expand. H 4 5. The process of forming an electricheater having a core of refractory non-conducting material having slits formed longitudinally thereof; which consists in winding a resistance element in said slits; placing dielectric cement in said slits tohold the element in position; and supplying current to the element before the setting of the cement is complete.

6. The process of forming an electric heater having ducting material which consists in machining slits in said core longitudinally thereof;

winding a resistance element in said slits;

placing dielectric cement in said slits to old the-element in position; and supplying current to the element before the setting of the cement is complete.

7. The process of forming an electric heater having a core of refractory non-conducting material havin slits formed longitudinally thereof whic consists in winding a ribbon resistance element on the edge in said slits; placing dielectric cement in said slits to hold the element in position; and supplying current to the element before the setting of the cement is complete.

8. In an electric heater, the combination of a housing having one closed end; a solid removable core of refractory non-conducting material in said housing, a space being left at the open end of the housing; a resistance element on said core; lead wires connected with the resistance element; means for closing the .open end of the housing,-

said space being packed with a loose fibrous non-conducting material.

' 9. In an electric heater, the combination of a housing; a core of refractory non-conductingmaterial in said housing; a resistance element on said core; a tting into which lead wires may be led; means connecting the fitting to the housing;- said fitting being heat insulated from the housing.

10. In an electric heater, the combination of a housing for a heating element; a fitting into which lead wires may be led; means connecting ,the an asbestos washer between the housing and the fitting.

11. In an electric heater, the combination of a housing; a core of refractory non-conducting material in said housing; and aresistance element on said core, said housing being provided with a series of corrugations on its outer surface. t

12. In an electric heater the combination of a housing; a core of refractory non-conducting material in said housing; and a resistance element on said core, said housing being provided with a series of circumferential corrugations.

' heater, the combination 13. In an electric of a housing for a heating element, said housing having a threaded portion on its outer surface slightly spaced from one end and grooves'inthe outer surface of the end; and a band cast on said end and anchored in said grooves.

acore of refractory non-con-' fitting to the housing; andv .element set on edge in said 14. In an electric heater, the combination of a core of refractory non-conducting material; a resistance element on said core; and lead wires connected with the the resistance element, the lead wires and the ends of the element being integrally united.

15. In an electric heater, the combination of a housing and a core of refractory nonconducting material: a resistance element on said core;

said housing and connected with the ends ofthe resistance element, the lead wires and the ends of the element being integrally united.

16. In an electric heater, the combination of a core of refractory non-conducting material; a resistance element on said core, said core being provided with grooves adjacent one end into which the ends of the resistance element are led; lead wires extending into said grooves and connected with the ends of the resistance element, the wires and elements-being integrally united, said grooves being packed to enclose the joints between the wires and elements.

17. In an electric heater, the combination of a housing for a heating element, said housing being provided with a series of corrugations on its outer surface; a conduit for lead wires; means connecting the conduit to the housing; and means for checking the passa e of heat from the housing to the condui 18. In an electric heater, thecombination of a housing and a core of refractory nonconducting material; a heating element; and lead wires extending into said housing ends of and lead wires extending into and connected with the ends of the resistthe combination.

terial having a plurality of slits formed longitudinally thereof; a ribbon resistance slits, said resistance being held in position by dielectric cement; and lead wires connected with the ends of the resistance element; the lead wires and the ends of the element being integrally united.

20. In an electric heater, the combination of a core of refractory, non-conducting material having a plurality of slits formed longitudinally thereof; and a ribbon resistance element set on edge in said slits, said resistance being held in place with dielectric cement, said core also being provided with grooves adjacent one end into which the ends of the resistance element are led; lead wires entending into said grooves and connected with the ends of the resistance element, the wires and elements mg' nwith the resistance element; means for closv 7 face of the tegrally united, said to. enclose the joints element.

21. In an electric-heater, the combination of a housing having one closedend; a ,re movable core of refractory non-conducting material in said housing, a space being left at the open end of the housing; a resistance element on said core; lead wires connected with the resistance element; means for closing the open end of the housing, being packed to check the admission of moisture to the interior of the housing, said housing being provided with a series of one rugations on its outer surface.

22. In an electric heater, the combination of a housing, for a heating element, said housing having a threaded portion on its outer surface slightly spaced from one end and grooves in the outer surface of the end; and a band cast on said end and anchored in said grooves, the remainder of the outer surhousing being provided with a series of corrugations.

23. In an .electric heater, the combination of a housing having one closed end: a removable core of refractory .non conducting material in said housing .a space being left atthe open end of the housing; a resistance element on said core; lead wires connected between the wires and ingthe open end of the housing, said space being packed to check the admission of grooves being packed said space 1 moisture to the interior of the housing; and a conduit secured to said housing, said first mentioned means being adapted to prevent liieatpassing from the housing to the conuit.

24. In an electric heater, the combination of a housing having one closed end; a removable core of refractory non-conducting material in said housing, a space being left at the open end of the housing; a resistance united with the resistance element;

said space being packed to check the admis sion of moisture to the interior of the housmg.

25. In an electric heater, the combination of a housing, for a housing having a threaded portion on its outer surface adjacent one end, said end having an irregular outer surface; and a band cast'on said end having the irregular outer surface.

26. In an electric heater, the combination of a housing for a heating element; a fitting into which lead wires may be led; means connecting the fitting to the housing, said fitting being adapted to be rotarily adjustable relative to the housing, said fitting being heat insulated from the housing.

Signed at Brantford, Ont., this 18th da-v of September, 1922.

'- JAMES ALEXANDER mnnomw housing,

heating element, said

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