US2355687A - Electric heater - Google Patents

Description

Aug. 15, 1944. 1 E. VAN HlsE ELEGTRIC'HEATER Filed May 51, 1941 s sheets-sheet i INVENOR. Leser E t/Z) M ATTORNEY.

Aug- 15, 1944- L. E. VAN HlsE 2,355,687

ELECTRIC HEATER Filed May 51, 1941 3 Sheets-Sheet 2 ff m ,f2/w14 M50 l INVENTOR. esler E l/an /f/se /32 BY j/Z ATTORNEY.

Aug 15, 1944. L. E. VAN HlsE 2,355,687

ELECTRIC HEATER Filed May 3l, 1941 3 Sheets-Sheet 5 INVENTOR .-eer E Vai? H/.Se

ATTORNEY.

Patented Aug. 15, 1944 ELECTRIC HEATER Lester E. Van Bise. Los Angeles, Calif., assigner, by mesne assignments, to Norman E. Coles. Los

Angeles, Calif.

Application May 31, 1941, Serial No. 395,955 In Japan December 19, 1939 16 Claims.

This invention relates to a device for heating a liquid, such as water, by electricity. The heating may be for the purpose oi'A providing hot water, as for domestic consumption, or it may be tor the purpose of generating steam or vapo or the like. l

Numerous devices have been proposed and used for such purposel or purposes. In some of these, the heating current has been passed directly through the liquid spaced carbon elements immersed in the liquid sewing to conduct the current to and from theliquid.

It has been found that in this type of heater,

the electrodes are soon coated with deposits, especially when the usual city water is the liquid that is being treated. The resultant necessity for frequent repairs and replacements is a serious disadvantage of this kind of heater.

It is an objectof this invention to provide a heater wherein the electrodes are so arranged that after initial vaporization of the liquid, an arc discharge is formed through the vapor, the heat of the arc serving to heat and vaporize theincoming liquid.

It is another object of this invention to provide a'n electrical heater of the type using submerged elements, so arranged as to prevent deposition oi solid matter on the elements.

.It is still another object of this invention to provide such a heater wherein the incoming liquid is caused to pass about the outside of annularly arranged elements to absorb such heat as vmay pass through an outer electrode and prevent its loss through radiation bythe body of the heater.

vIt is still another object of this invention to provide a heater comprising means whereby a small now of liquid through the heater, as, by accident, will be prevented from activating the kheating elements.

tories or the like of simple and durable design v and easy of installation.

This invention possesses many other advantages, and hasA other objects which may be made more easily apparent from a consideration of several embodiments of the invention. For this purpose there are shown a few forms in the drawings accompanying and forming part of the present specification. These forms will now be described in detail, illustrating the general principles of the invention: but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of the invention is best deiined by the appended claims.

In the drawings:

Figure 1 is a longitudinal sectional view of a lavatory heater embodying the invention;

Fig. 2 'is a sectional view, taken along piane 2-2 of Fig. 1;

Figs. 3 and 4 are fragmentary longitudinal sectional views, as taken along correspondingly numbered planes of Fig. 2;

Fig..E 5 is a longitudinal sectional view, taken along 'plane 5 5 of Fig. l;

Figi 6 is a cross sectional view, taken along plane 6 8 oi Fig. 5:

Fig'. 7 is a fragmentary sectional view, taken in the plane of Fig. l, showing a terminal structure used in connection with the invention;

Fig. 8 is a section as seen on plane 8 8 of Fig. '7

Fig. 9 is an elevation of the underside of an 25 other terminal structure used in connection with fthe invention;

Fig. 10 is a sidev elevation of the structure of Fig. 9; f

Fig. 1i is a side elevation of the connector 30 used with the terminal structures:

Fig. 12 is a top plan view thereof;

, Fig. 13 is a side elevation of the cover for the body;

Fig. 14 is a view of the underside thereof;

Fig. 15 is a side elevation of the cap for the outside heating element;

Fig. 16 is a bottom pian view thereof;

Fig. 1'7 is an elevation of a modied form of the invention;

Fig. 18 is a similar view, partly in section;

Fig. 19 is a top plan view of the structure of Fig. 18; and

Fig. 20 is a fragmentary transverse section as seen on plane 20--20 of Fig. 19.

In that form of the invention illustrated in Figs. 1 to 16, a compact instantaneous water heater for lavatory purposes is disclosed. Therein, a pair of cylindrical electrodes, I and 2, of suitable material such as carbon, are nested con- 50 centrically within an enclosing housing or casing 3. 'I'he housing 3 and electrodes l, 2, cooperate to dene narrow vertical annular spaces l, 5 for the passage of the liquid to be heated and are mounted on a base 6. The base 6 as will be more 55 fully described later, comprises various passageways by which liquid is permitted to now from inlet 1 to the discharge spout 2. The passage oi' this liquid is controlled by valves or Iaucets l, III. One of these valves, as 2, serves to control the iiow directly from inlet 1 to spout 2. while the 5 other valve Il, serves to admit liquid to the annular spaces 4, where it is heated, before passing to spout l. By appropriately adjusting the openings of valves l, III, the temperature of the discharged liquid may be varied as desired. l

'l'he arrangement is such that the annular space 4, between elements I and 2 is relatively very narrow. Thus, the liquid entering this space passes between the electrodes in a thin sheet through which the current passes between the i electrodes in the form of a multitude of arc discharges. These heat the passing liquid and may even vaporiae a portion of it.

By appropriate choice of the space 4 between the electrodes 'I and 2, it is possible to produce 2o heating effects other than that caused directly by the electrical energy expended. Apparently there is a breakdown, by the arc, of atoms of the constituents of the liquid, releasing additional heat,

and giving a total heat output greater than that 25 represented by the expenditure of the electrical energy. Although no very speciilc rule can be stated ior the separation of the electrodes l and 2 for securing these results, it has been found that this separation should be about .045 inch when a 220 volt circuit is utilized. However, the character of the water has some eilect upon optimum spacing, it having been found'that vthe harder the water, the farther apart the electrodes may be spaced.

By reducing the ilow in accordance with the area oi the electrodes, it is possible to ensure complete vaporization, but such is obviously not desirable in the embodiment under discussion. By arranging that the liquid ilows downwardly between the electrodes. any solid matter tending to be deposited on the electrodes will be washed downwardly and out the discharge, together with any miscellaneous material carried by the liquid. Thus, any tendency of the heater to lime up is obviated.

Referring in more detail to the structure, the cylindrical carbon electrodes I and 2 are supported concentrically about a vertical axis II by means oi the hollow body 2, which is made of insulation material capable of withstanding the temperatures attained. Such material may be Bakelite, porcelain, a plastic product, or the like. This body 3 has an internal cylindrical space or cavity I 3 coaxial with axis II, is provided with 55 a ilange or wall I4 at its lower'end, having an annular recess I5 therein. This recess I5 forms a shoulder IB at the bottom of cavity I2, as well as a shoulder Il around the integral tubular extension I8 formed within body 2. These shoul- 60 ders IS and Il form supporting surfaces for electrodes 2 and I respectively. In order to give increased strength to extension Il it is made of tapering conguration so as to have an increased cross section adjacent its point of attachment I2 to wall I4.

A tubular member 2I of copper or other good conducting material closely embraces the outer electrode 2 and is in good electrical contact therewith. This member 2I serves to maintain the 70 electrode 2 coaxial with respect to cavity I3 in body 3 as well as with electrode 2, as will be presently described. Current for the electrode is supplied by a suitable connection to member 2|.

Similarly, the inner electrode I is in good electrical contact with a copper tube 22 accommodated in a central tapered bore 22. Bore 22 is oi auch size and taper that when electrode I is resting on seat Il, the electrode I is held axially by stem Il.

The terminal structures for the inner and outer electrodes I and 2 are clearly shown in Figs. l, 3 and 'l to l2. Thus at the upper end of tube 22 of the inner electrode I a metallic terminal flange 24 (see Figs. 9 and 10) is teleaeoped over the tube. This collar 24 has a wide radial extension 2l ior the accommodation ot a screw 2l to which is secured the terminal collar 2l.

The terminal structure for the outer electrode 2 includes a flanged metallic ring 22 telescoped within the upper end ot the tubular member 2| (see Figs. '7 and 8). 'I'his ring 2l has an inwardly directed extension 2l for accommodating a screw 20 to which is secured a terminal collar 2|, similar to collar 2l. A portion of ring 22 opposite extension 22 is omitted, to provide appropriate clearance for the terminal ilange 24 of the inner electrode I.

As shown most clearly in Figs. 1, 3, l5 and 16, a cover 2l of suitable insulating material extends over electrodes I and 2, and the annular space 4 between them. This cover has a central aperture 2i for accommodating tube 22 and stem Il. Aperture 26 is a close ilt over tube 22. Cover 22 has a depending flange 21, the lower face of which contacts the top of electrode, and the periphery oi which closeLv'iits within tubular member 2l. By this arrangement, member 2I and the outer electrode 2 are maintained coaxial with stem It, and hence with electrode I. To permit communication between the annular spaces 4 and l it is provided with a number ot cutaway portions 22 which are alined with openings 22 in member 2| during assembly.

, A spacer or separator 4I is mounted on cover 25 and within hanged ring 22, a suitable resilient gasket 42 being interposed between them. Separator 4I nts snugly within ring 22 and has a central aperture 42 for accommodating the upper end of stem Il, as well as a recessed portion 44 on its lower surface for accommodating terminal lug 24. The purpose of separator 4I is to effectively isolate the terminal structure 24--25- 26-21 of electrode I from the terminal structure 2a-22-20-2I of electrode 2, to ensure against l. arcing between them.

The assembly is made huid tight by means of a resilient ring gasket Il disposed on a shoulder II formed about the top of annular space I2. Gasket 50 is substantially on a level with gasket 42 and has a central opening l2 for accommodating ring 28. Above gasket l0 is a cap 52 (see also Figs. 13 and 14), formed of suitable insulating material. The under surface oi' cap 52 is provided with a recess B4 for accommodating ring 28 and separator 4I, and a central depression Il for receiving the upper end oi stem Il, as well as a through hole l2 for accommodating a long stud '51 which extends axially of stem Il. Stud l1 is secured in base l as by having its lower end threaded therein, a nut 52 threaded on the upper portion of the stud engagingv the upper surface oi' the cap 52, a suitable washer 59 being interposed. By means of stud l1, nut Il, etc. cap l2 may be clamped downwardly against gasket Il, spacer 4I and gasket 42. A gasket ll may also be provided between the top of stem Il and the bottom of recess Il. Further, this clamping is also effective to tightly secure body 2 to the base l.

Cap 58 is provided with recesses 53 and 84 in its upper surface to receive terminal collars 21 of the terminal collars 21, 3| comprises a cylin-` drical body13 having a threaded axial bore 14 extending through it. This bore 14 is oi two diameters, the portion of smaller diameter being to receive the mounting screw, 25, 30. The portion l of larger diameter has a headless set screw 15 threaded therein. I'his portion of the bore is intersected by a radial slot 18. The conductors 19, l are clamped respectively between the bottoms of bores 14 and set screws 15, being inserted into'the bore through slots 18. These conductors pass forwardly and downwardly of body 9, through apertures 8| into base member 8, whence they may lead to an appropriate source of electrical energy.

In order to present a smooth, finished appearance, a metallic domed cover 8,4 (Figs. 1, 3, and 6) may be provided. This cover 84 closely embraces the rear and side portions of body 3 (see Fig. 6) but is swelled out in front as indicated by 8l to accommodate leads 19, 80. The loweredge of cover 84 rests on the upper surface of base member 5, which is shaped to conform therewith. Cover 84 is held in place by the aid of a screw 88, passing through the top of cover 84 into a threaded aperture formed in the upper portion of stud 51.

Body 3 may if desired have a protective sleeve 81 of metal or the like, for purposes of reenfor'cement, over which cover 84 is telescoped.

Water or other liquid to be heated is supplied to the annular space 4 through an opening 90 (Figs. 1 and 2) formed in body 3 and-extending downwardly through a boss 9| on the bottom of body 3. The base or supporting member 6 has an aperture 92 into which boss 9| extends. A sealing gasket 99 accommodated in a recess 94 in the bottom of body 3 provides a fluid tight connection. Thus, port 90 connects with a passageway 95 formed in base 5 and leading to a control valve or faucet structure I0 to be presently described.

'Ihe water is forced upwardly, by the pressure of the source of supply, into annular space 5 about the outer electrode 2, absorbing heat therefrom that would otherwise be radiated by the body and wasted. The water then passes through openings 39, 30 into the annular space 4 between the electrodes I and 2, where it passes downwardly, being heated by the action of the arc formed between these electrodes as before mentioned. The heated water then passes into the annular space I5 (Figs. l and 4) formed in the bottom of body 3. Thence it proceeds through port 98 (Figs. 2 and 4) into a .passage 99 and is discharged through a spout 8 formed integrally with base 8. Port 98 extends through a boss |0I, similar to boss 9| and maintained in fluid tight relation to base 5 in the same way.

The means for supplying water to the intake passage 95 may now be set forth. Base member 5 has a downwardly extending integral post |02 (Figs. l, 4 and 5) with a threaded extremity. Through it extends a water inlet passage |05 communicating with supply pipe1, joined in a l and I I, as well as the leads thereto. Holes 85 and Y l5 (Fig. 14) extendv through the cap from reconventional fluid tight manner to the end of post |02. Furthermore, this post |02 may be arranged to pass through a hollow metal casing member N5. disposed on the bottom surface of a supporting wail`l01... This supporting wall |01 may represent a portion of a wash basin or the like with which the device is adapted to cooperate. A gasket |08 may be disposed in a suitable recess |08 in the lower edge of a. flange |09 formed integrally with base member 8, and in contact with the top surface of wall |01. It is apparent that by tightening the nut I I0 on the threaded extremity of post |02 the assembly may be tightened upon wall |01 and thereby supported. It4

may be noted that as shown in Fig. 5, the conductors. 19 and 80 pass through the space formed around post |02 by the casing |05 and ange |09- and extend outwardly through an opening in casing |05.

'I'he inlet conduit |03 extends upwardly and connects with a horizontall conduit ||2 formed in the b ottol'nof base member 8. The left hand end of conduit ||2 is adapted to be placed in communication with conduit 95 leading to inlet port through a control valve or faucet structure I0. Thus there is a boss ||3 extending upwardly from the top surface of member 5 (see Fig. 1) and having a bore I4 intersecting passage and extending beyond this passage. Boss ||2 is externally threaded at its end for the accommodation of a gland n ut I I5. Fitted within bore ||4 is a tubular valve body ||6 internally threaded in its upper portion, its lower edge resting on `a sealing washer ||1, which surrounds an opening |I8 extending between passage'II2 and the interior of body IIS. Valve body I|5 has a plurality of radial apertures |20 arranged at such a height as to aline with conduit 95. In this way it is assured that the interior of valve body ||8 is in communication with conduit 95 regardless of the angular position oi' body IIS in boss III. Thus with the valve open, water can pass from passage |I2 through opening ||8 into body I|8 and thence through one or more apertures |20 into conduit 95.

A valve closure IIS, in the form of a cylindrical member, has a lower face Aadapted to seal against washer I1, and is loosely mounted on the ball end 2| of a valve stem |22. Valve stem |22 has a`n enlarged threaded portion |29fengaglng the threads in body H6. These threads have a coarse pitch, so that rotation of stem |22 through substantially less than a complete revolution suillces to lift closure I I9 a suitable distance above washer I I1. Stem |22 may be packed by suitable material |24 disposed in gland nut |I5 and may have a handle |25 secured thereon for convenient manipulation.

It may be desirable to restrict the amount of liquid that can ilow into inlet passage 95 even when valve I0 is fully opened. Forthis purpose the left hand end portion |28 of passage I I2 is provided with screw threads extending beyond opening |I8. A headless screw |21 is positioned in this threaded portion |25 which is adapted to close opening ||8. By adjusting the position of screw |21 the effective area of opening ||8 may be altered, whereby the maximum ilow of Water from passage ||2to passage 95'and thence into the inter electrode space 4 may be controlled; and accordingly the degree of heating may be regulated. A headed screw |28 serves to close the end of passage ||2 in a iluid tight manner.

The spout 8 isintended to discharge a mixture of water heated by passage between the electrodes, and water directly from inlet 1, whereby by appropriate independent regulation of the faucets 5, I5, water of a desired temperature may be obtained. Thus, a passage |25 extends to the right from inlet |55 (Flgfl) and has an upward extension for supplying water into the interior of valve body |55, of a valve 5, the general struc'- ture of which is the same as that of valve i5. for controlling the iiow of hot water. Valve l has a handle |52 for convenient manipulation.

Valve 5 is adapted to pass water into conduit |55 which communicates directly with spout 5 (Fig. 2) and is separated by wall I 54 from the hot water outlet 59.

It may sometimes happen that the valve or faucet I controlling admission of water to be heated is not tightly closed, so that a small amount of water would be admitted into the annular spaces and 5 and there heated. This would result in substantial waste of current. To

prevent this, adjacent the lower edge of electrode 2| a restricted bypass or port |55 (Fig. 1) is provided between the inlet port 50 and annular space l5 in the bottom of body 5. As shown port |55 is formed by a notch in the bottom oi' electrode 2, but it could obviously be formed equally well in body 3. This bypass |55 permits a small amount of water passing valve i5, due to leakage or otherwise to pass directly to spout 5 without entering space 5. However, it has no material eect upon the quantity of water passing into this space to be heated when valve i5 is purposely opened.

'I'he mode of operation of the device will be apparent from the foregoing. Upon manipulating either of the handles |25 and |52 or both to open their associated valves I5, 5, water is discharged through spout 5, the relative extent of opening of the valves controlling the proportion of the water that is heated and hence the temperature of the water delivered. Due to the fact that the flow of liquid between the electrodes is downward, any tendency for sediment to collect is obviated. Foreign material or dirt is washed out by the stream.

The device is not restricted to use as an instantaneous heater of liquid, but by appropriate However, instead of a supporting base 5, bodyA is provided with a simple closure member |56 on its lower end and is intended to be supported in any convenient manner, as for example by the pipes which conduct fluid to and from the heater. 2

As clearly shown in Fig. 20, cover member |55 has a central hub |55 for threadedly receiving stud 51 by means of which the upper and lower covers |55 and |55 are clamped to the body |55. Cover |55 has a radially extending threaded boss |55 having a port |50 intersected by a port |5|. Port IBI terminates in an nlarged space I 52 for receiving boss 9|. Inlet pipe |55 for the liquid to be heated is secured by a conventional connection to boss |55 in a fluid tight manner and therebyfcommunicates with inlet port 55 of body |55. Cover |55 has a similar space |55 (see ll'ig. 18) for receiving boss |5| through which extends a discharge port. A downwardly extendingthreadedboss |55hasaport |55 forcooperating with port 55. A discharge pipe |51 is threadedly connected to boss |55.

As a means'of precisely regulating the inflow of liquid through port |5|, a cone pointed screw |55 is provided. This screw is threadedly en- Based in bos |55 formed on boss |55 and having a threaded portion axially alined with port |5|. By adjusting the axial position of screw |55 the effective opening of port |5| can be altered. A closure cap |1| is threadedly attached to the exterior of bou |55.

For conveniently controlling the flow of liquid to the heater within the limit set by adjusting screw |55, a valve |12 (Fig. 1'?)l is provided in inlet conduit |55.

What is claimed is:

1. The method of electric heating which cornprises passing an arc through vaporized liquid disposed between electrodes presenting active surfaces suiliciently close to produce heating by atomic breakdown, said electrodes being permanently spaced at about .045 inch apart when a source of current at 220 volts is utilized.

2. In a device of the character described. a pair of electrodes so spaced as to form a passageway between them for the accommodation of liquid to be heated, means for supplying liquid to the passageway, including a valve and means forming an outlet from the passageway, there being a continuously open restricted bypass from the valve to said outlet and paralleling said passageway.

3. In a iiuid heater, a pair of electrodes form-- ing a substantially vertical passage between them, means forming a second substantially vertical passage adjacent one of the electrodes, means ior supplying liquid to said second passage adjacent the bottom thereof, means for permitting 1iquid to iiow from the second passage to the rst passage at the top oi' said passages, means for passing a current through 1iquid between said electrodes, means forming an outlet from the bottom of the first passage, and means forming a restricted bypass opening between the bottoms of said passage.

4. In a iluid heater, a pair of electrodes so spaced as to form a passage between them for the accommodation oi' liquid to be heated, means for supplying liquid to the passage including a valve, means forming an outlet from the e, and means independent of the valve, forming a restricted port between the supply and the outlet, whereby a limited vquantity of liquid passing the valve will enter the outlet without entering the passage.

5. In a water heater, a body having a closed cavity, electrodes within said cavity defining a space for the passage of water, said water in said space being adapted to be heated by the passage of current between said electrodes, a base for supporting the body, said base having a water inlet as well as a discharge spout, means for passing water from the inlet to the interelectrode space, means for passing water from said space to said spout, means in said base for passing water directly from the inlet to the spout, and means for independently controlling the passage of water through said space to the spout and directly t0 the spout.

oi' annular spaces, the outer oi said spaces being l between the body and the outside electrode, the other-.space being between the electrodes, means whereby said spaces are in communication, a base member generally conforming with the -shape of the body for supporting the body. said base having passageways forming a water inlet as well as a discharge spout, means forming a passage fromv said inlet to one of said annular spaces, means forming an outlet from the other of said spaces to said spout, means forming a passage from said inlet directly to said spout, and valve means for independently controlling said passages.

7. In a water heater, a generally cylindrical body having an enclosed circular cavity, a pair of circular nested electrodes mounted coaxially in said cavity and deilning a pair of vertical annular spaces, one of said spaces being between the electrodes, the other space being between the outer electrode and the wall of the cavity, means whereby said spaces are in communication at their upper ends, a base member on which the body is supported, said base havingpassageways forming a water inlet as well as a discharge spout, means forming a passage from said inlet to the bottom of said outer space, a vvalve for controlling said passage, means forming a passage from the bottom of said inner space to said spout, a passage from aid inlet directly to said spout, and a valve for controlling said last mentioned passage.

8. In an electric heater, a pair of coaxial cylindrical electrodes dening a vertical annular space between them, means for passing a current through liquid between said electrodes, a base supporting both of said electrodes at the bottom, and a spout carried by the base,7 said base having a passageway between the lower end of said annular space and the spout, said base having another passageway for passing liquid upwardly into the upper part of said annular space.

9. In an electrical heater, a base member having inlet and outlet passages, a pair of concentric inner and outer electrodes forming a vertical annular space between them, a central tapered supporting post cooperating with a corresponding tapered aperture in the inner electrode, and supported on the base, and means forV maintaining the outer electrode in coaxial position with respect to the inner electrode and disposed adjacent the top of the electrodes, said inlet and outlet passages communicating with opposite ends of the annular space.

10. In an electrical heater, a base member having inlet and outlet passages, av support made from insulation material and disposed on the.

base, said support having a tapered central post.

an inner cylindrical electrode telescoped over said ing inlet and outlet passages, a support made from insulation material and disposed on the base, said support having a tapered central post, an inner cylindrical electrode telescoped over said post, an cuter cylindrical electrode deiinlng a vertical annular space with said inner electrode, and having a lower edge disposed on said support, a spacer member of insulation material disposed between the upper ends of said electrodes, said support having an annular portion extending upwardly around and spaced from the outer electrode, and a cover member of insulation material disposed over the electrodes and in iiuid tight relation to said annular portion.

v12. In an electrical heater, a base member having inlet and outlet passages, a support made from insulation material and disposed on the base, said support having a central post, an inner cylindrical electrode disposed on said post, an outer cylindrical electrode dening a vertical annular space with said inner electrode, and having a lower edge disposed on said support, a spacer member or insulation material disposed between the upper ends of said electrodes, said support having an annular portion extending upwardly around and spaced from the outer electrode, and a cover member of insulation material disposed over the electrodes and in iiuid tight relation to said annular portion, said inlet\ passage communicating with the space around the outer electrode, and said outlet passage communicating with the lower portion of the annular space between the electrodes.

v 13. In an electrical heater, a base member having inlet and outlet passages, a pair of concentric inner and outer electrodes forming a vertical annular space between them, and means for maintaining said electrodes in true concentric relation and for supporting said electrodes on the base, said means having an annular portion spaced from and surrounding the outer electrode. said inlet passage communicating with the space around the outer electrode, and said outlet passage communicating with the lower portion of the annular space between the electrodes.

14. In an electrical heater, a base member having inlet and outlet passages, a pair of concentric inner and outer electrodes forming a vertical annular space between them, and means for maintaining said electrodes in true concentric relation and for supporting said electrodes on the base, said means having an annular portion spaced from and surrounding the outer electrode, said inlet passage communicating with the space around the outer electrode, a cover member of insulation material disposed over the annular -f space and supported by aid of said annular portion of the support, and terminal structures for the electrodes supported by the cover member.

15. In an electrical heater, a base member having inlet and outlet passages, a pair of concentric inner and outer electrodes forming a vertical annular space between them, and means for maintaining said electrodes in true concentric relation and for supporting said electrodes on the base, said means having an annular portion spaced from and surrounding the outer electrode, said inlet passage communicating with the space around the outer electrode, a cover member of insulation material disposed over the annular space and supported by aid of said annular portion of the support, and terminal structures for the electrodes supported by the cover member, each of said terminal structures including a metal ring in electrical connection with the respective electrodes, the rings being concentric, as well as an ear extending from the ring.

16. In an electrical heater, a base member having inlet and outlet passages, a pair oi' concentric inner and outer electrodes forming s. vertical eninsulation msterisl disposed over the mnuhr nularspsce between them, and means for msinspsee end supported by nid of nid annuler porteining seid electrodes in' true concentric relstion ot the support, und termine! structures for tion and for supporting said electrodes on the the electrodes, each bovina e eonduetor receiving base, said means havin: an annular portion s member supported mpectively in recesses in the spaced from and surrounding the outer electrode, cover.

said inlet passage communicating with the space mm E, VAN HIBI. around the outer electrode. s cover member ot

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