US2377785A

US2377785A - Electric furnace water heater

Info

Publication number: US2377785A
Application number: US499969A
Authority: US
Inventors: Walter E Hudson
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-08-25
Filing date: 1943-08-25
Publication date: 1945-06-05
Anticipated expiration: 1962-06-05

Description

June 5, 1945. w. E. HUDSON ELECTRIC FURNACE WATER HEATER Filed Aug. 25, 194s tiarney Patented June 5, 1945 UNITED sTATEs PATENT OFFICE ELECTRIC rFURNACE- WATER HEATER Walter E. Hudson, East Setauket, N. Y. v Application August 25, 1943, Serial No. 499,969

(Cl. 21S- 39) 19 Claims.

This invention relates to water heaters and particularly to electric water heaters for domestic use.

One object of the invention is a novel and improved heater which is characterized by its high heating efficiency and by its adaptability to quantity production at a low cost.

A further object of the invention is a novel and improved water heater which is capable of meet- I called upon to supply heated water and with the l heated water for immediate use being drawn mainly from the upper levels of the water reservoir downwardly through heating chamber.

Further objects of the invention will 'hereinafter appear.

For a better understanding of the invention reference may Ibe had to the accompanying drawing forming a part of this application wherein,

The drawing is a sectional view through the center of the water heater.

Referring to the drawing, I have shown my invention as embodied in a water heater embodying an elongated vertical tank I of suitable metal. The bottom of the tank is indicated at 2 and the tank maybe supported on a floor or on other supports at its bottom edge 3. The top closure comprises an inwardly extending flange member I9. The tank walls I, 2 and I 9 may be insulated, if desired, against the transfer of heat.

Within the tank is disposed a concentrically located enclosure or sleeve 4 telescopically arranged with a heating unit and forming a water heating and circulating chamber thereabout as hereinafter described. In the embodiment shown this telescoping member 4 is in the form of a cylinder or sleeve resting at its lower end on the bottom 2 of the main casing. This member 4 is provided at the bottom with a closing and locating plate 5 of suitable material, as for example, steel, this plate 5 being disposed within the lower end of the member. This member is located and anchored centrally of the main casing I by means of a hot water supply pipe 6 which is screwthreadedly attached to the plate 5 and passes upwardly through the bottom 2v of the main casing and centrally thereof. In order to strengthen the central bottom structure a metallic plate I is disposed centrally of the bottom 2 and exteriorly thereof with the hot water supply pipe 6 being screw-threadedly attached to this plate also. This plate 'I may be brazed or otherwise fastened to the bottom 2, as for example, as indicated by the welds 8. The pipe 6 should make a water-tight joint at the opening formed in the bottom 2 at 9 so as to form a seal against the leakage of water. If desired, a similar leak-proof seal may be provided between the pipe 6 and the

plates

5 and 1.

The elongated sleeve 4 is thus anchored concentrically of the main casing I by means of the hot water supply pipe 6 and the strengthening and

anchoring plates

5 and 1. The sleeve 4 is provided with an insulating space or jacket exteriorly thereof by the provision of a jacket I0 which is fastened and sealed along the edges I I and l2 at the bottom and lower edges thereof to the n exterior surface of the sleeve. This fastening and sealing of the jacket wall I0 to the sleeve 4 may be effected in any desirable and conventional manner.

Centrally disposed with respect to the casing I and telescopically arranged with respect to the sleeve or partition 4, a heater casing I5 extends downwardly into the sleeve 4 with an annular water-heating chamber A of small cross-sectional area provided .between the two members 4 and I5. The heater casing I5 stops short of the bottom of the casing I or the plate 5 to form a small chamber or auxiliary reservoir B vbeneath the casing I5, and extends to a-point approaching the inlet end of the supply pipe 6. Thesleeve 4 is provided with one or more restricted Openings Il for establishing communication between the chamber B and the main reservoir C surrounding the members 4 and I5. The area of the inlet or inlets I1 is restricted as compared with the cross-sectional area of the annular water heating chamber A for the purpose hereinafter described The heater casing I5 is provided at its upper end with an outwardly extending flange I8 and this :fiange is supported upon the annular top closure rI9 projecting inwardly from the casing wall I at the top. For facilitating the fastening of the flange I8 to the flange I9 an annular member or ring 20 is fastened on top of and near the inner edge of the ring I9. 'Ihis ring 20 may be fastened in any suitable manner, as for example,

by brazing or welding. The flange I8 of the heater casing I5 rests upon this ring 20 and is fastened thereto in any suitable manner as for example by the bolts 2| passing through openings formed in the flange I8 and screW-threadedly attached to Screw-threaded recesses formed in the ring 20. As many securing bolts 2 I may be provided as needed for holding the casing I firmly attached to the upper closure I9 of the outer casing I of the heater, and preferably a water tight seal is maintained between this closure.

The heater casing I5 may be provided with spring spacers 22 disposed about the exterior surface thereof so as to bear against the interior surface of the sleeve or partition 4. These spring spacers or lugs 22 function to center the heater casing within the sleeve or partition 4 and preferably the openings formed in the flange I8 of the casing I5 are larger than the bolts 2I so as to facilitate adjustment and centering of the casing with respect to the telescoping member 4 which is fixed centrally of the bottom 2 of the tank or casing I.

The heater housing or casing I5 is provided with a readily removable electric heater unit. This heater unit comprises three insulating plates held firmly .in spaced relation by a central shaft or rod 25. There is a -bottom plate 26, a top plate 21 and an intermediate plate 28. The bottom plate 26 is preferably circular to conform to the cylindrical heater housing l5 and the lower end of the rod or shaft is fastened in any suitable manner lto the plate 26, as for example, by being provided with a head 25 embedded in the plate. The upper end of the rod 25 is provided with an exterior screw thread and the

plates

21 and 28 are supported on and carried by this rod or sha-ft Z5 by means of two pairs of

nuts

29 and 30. These nuts are screwed tightly against the upper and lower surfaces of the plates so as to hold them tightly in spaced relation with the plate 21 resting upon the flange I8 of the heater casing and with a dead air space D formed between the two

plates

21 and 28 and within the upper end of the heater casing. The plate 28 preferably conforms to the interior surface of the heater casing I5 so as to isolate the electric heat- 21 in any suitable manner, as for example, by passing uncoiled parts of the heaters up through the

plates

28 and 21 and through the dead air space D. In the particular embodiment shown I have illustrated these connections as rods 39 forming parts of the terminals 38 and having screw nuts engaging the upper surface of the plate 21, while the lower ends of the rods 39 are provided with similar nuts 4I screwthreadedly attached to the rods and engaging the under surface of the plate 28.

The heat radiated from the heaters 35 is insulated by the

plates

26 and 28 against the passage chamber C near the bottom thereof.

ing chamber E from the dead air space D. The

plates

21 and 28 are adjusted so as to cause the bottom pla-te 26 to rest upon or approach the bottom I5 of `the heater casing. The plate 21 is shown of the same diameter as the flange I8 and is provided with recesses 3l to accommodate the heads of the bolts 2I. Preferably the plate 21 is held tightly against the flange I8 of the heater casing so as to form a substantially air-tight seal between the space D and the outside atmosphere. Any suitable means may be provided for holding the plate 21 upon and against the flange I8 and in the particular embodiment shown, I have illustrated thumb screws 32 which are screw-threadedly attached to screw-threaded openings formed in the plate 21 and similar screw-threaded openings formed in the metal ring 28, only one of these thumb screws being shown for convenience in illustration. The flange I8 is provided with openings to accommodate these thumb screws 32.

I have diagrammatically illustrated the electric heater as mounted between the

plates

26 and 28 and comprising a multiplicity of coils 35 only two of which are shown but it being understood that preferably four and more, if desired, may be employed. These electric heaters 35 are electrically connected at their lower ends in pairs by suitable connections 35 disposed, in slots 31 formed longitudinally of the insulating plate 2B. These coils or spirals 35 may be connected with electric terminal posts 38 mounted on the plate of the heat longitudinally of the heater casing or housing and is forced to pass through the comparatively thin metal wall I5 of the heater housing into the annular water heating chamber A. This chamber A is elongated but is of comparatively small cross-section so that only a comparatively small body of water is heated at one time. The heating of the water in the chamber A results in the upward movement thereof into the upper part of the outer reservoir C of the casing, while the colder water passes through the restricted openings I1 into the chamber or auxiliary reservoir B and is forced upwardly into the water heating chamber A. The cold water is supplied through a pipe 42 which enters the The dead air space formed between the members 4 and I0 functions to insulate the heated water in the chamber A against the colder water immediately surrounding the partition or sleeve. During the normal water-heating process, when no Water is being withdrawn through the pipe 6, the natura-l circulation of the water is upwardly through the heating chamber A into the surrounding reservoir C and downwardly therethrough. However, when there is a demand for hot water the pipe 6 withdraws the water from the top of the auxiliary reservoir B and any appreciable demand of hot water results in the withdrawal of water downwardly through the chamber A. This is because the resistance to the passage of water in this direction is less than the resistance encountered by the water in passing through the restricted openings I1. The heated Water thus is drawn from the top of the reservoir C where the water is hottest, then downwardly through the heating chamber A where it is further heated during its downward passage. This reverse circulation of the water through the chamber A continues as long as there is any appreciable demand of hot water through the pipe 6, and the sleeve of water being drawn through the water heating chamber A is subjected to the large heating surface I5 about the electric heating chamber E with resultant instant and quick heating to supply a long continued demand.

The outlet pipe section 6 functions, as described above, to hold the circulating sleeve 4, I0 in the central position, and also it may be adjusted up and down by means of the screw threads shown to bring the upper end of the outlet section closer to or farther from the bottom I5 of the heater casing, The particular construction, mounting and suspension of the heater casing tend to offset the effects of expansion and contraction upon changes in temperatures.

I claim:

1. In an electric water heater, an elongated cylindrical casing, a centrally disposed cylindrical sleeve extending upwardly from the bottom of the casing to a level near the top of the casing, said centrally disposed sleeve forming with the side wall of thecasing lan annular cylindrical Water reservoir'thereabout, a cylindrical heater housing unit suspended from the top of the casing and extending downwardly into the central cylindrical sleeve and forming with the interior of the same an elongated annular water-heating chamber of small cross-sectional area, said housing stopping short of the bottom of the casing and forming a relatively small reservoir in the bottom of the sleeve with said Water-heating chamber communicating at the v'top with the Arst named reservoir and at the bottom withthe second-named reservoir, saidy second-named reservoir having a restricted communication through the wall of the enclosure at a level below thev lower end of the heater housing, said heater rhousing having atlthe top thereof a dead air space and having electric heater elements in the lower part of Said heater' housing co-extensive with the height of said :water-heating chamber, a cold 0f the casing to a levelA nearthe top of the casing, said centrally disposed sleeve forming with the side wall of the casing an annular ycylindrical water reservoir thereabout, `a cylindrical heater housing unit suspended from the top of the casing and extending downwardly into the central cylindrical enclosure and forming with the interior of thesleeve an elongated annular waterheating chamber of small cross-sectional area, said housing stopping-short of the bottom of the casing and forming a relatively small reservoir in the bottom of the sleeve with said water-heating chamber communicating at thejtop with the rstnamed reservoir'and at the bottom with the second-named reservoir, said second-named reservoir having a restricted communication through the wall of the enclosure rat a-level belowthe lower end of theheater housing, said heater housing having electric heater elements'in the lower partcf said rheater housing co-extensive with the height of said water-heating chamber,` a cold water inlet leading into the casing at a point near the bottom'thereonand a hot, water outlet disposed centrallyof the bottom of the casing and extending upwardly `to a point abovethe level of said communicating passage and to a level slightly below thebottom of the heater housing.

3. In an electric water heater, 'an 'elongated cylindrical casing, a centrally disposed cylindrical sleeve extending upwardly from the bottom of the casing to a level near the top ofthe casing, said centrally disposed enclosure forming with the side wall of the casing an annular cylindrical water reservoir thereabout, a cylindrical heater housing unit suspended from the top of the casing and extending downwardly into the central cylindrical sleeve yand forming with the interior thereof an elongated annular waterheatingfchamber of small cross-sectional area, said housing stopping short of the bottom of the casing and forming a relatively small reservoir in the bottom of the sleeve with said water-heating chamber communicating at the top with the rstnamed reservoir and at the bottom with the second-named reservoir, said second-named reservoir'rhaving 'a restricted vcommunication .through the wall of the enclosureat alevel belowthe lower end of thefheater housing, 4said heater housing having electric heater elements'in the lower `part of said heater housing co-extensive with the height of said water-heating chamber, a cold water inlet leading into the casing at a point near the bottom thereof, and a hot water outlet disposed centrallyiof the bottom of the. casing and extending. upwardly. toy a point above the level of said communicating passage and to a klevel slightly below the bottom of the' heater housing, said centrallyr disposed sleeve being insulated against the transfer of heat throughout the length ofthe water-heating chamber. y i

4. In an electric water heater, anl `elongated cylindrical casing, a centrally disposed cylindrical sleeve extending upwardly. from the bottom of the casingto a level near the top ofthe casing, said centrally disposed sleeve forming with the side wall `of the casing an annular cylindrical Water reservoir thereabout, a cylindrical heater housing unit suspended from the top of the casing, and extending downwardly into ther central cylindrical enclosure and forming with Athe interior of the sleeve an elongated annular waterhe'ating chamber of small crosssectional area, said housing stoppingshort of the bottom of the casing and forming a relatively small reservoir-,in the bottom of the sleeve with said water-heating chamber communicating at the top with the rstnamed reservoir and at the bottom with the second-named reservoir, said second-named reservoir having a restricted communication through the wall of the enclosure at a level below the lower end of the heater housing, ysaid heater housing having electric heater elements in the lower part of said heater housing co-extensive with the height of said water-heating chamber, a cold water inlet leading into the casing at a point near the bottom thereof, and a hot water outlet disposed centrally ofthe bottom of thecasing and extending upwardly to a point above the level of said communicating passage and to a level slightly below the bottom of the heater housing, the top of saidr casing comprising aninwardly extending flange with a metallic ring rmounted thereon and said heatervhousing havingan outf wardly extending ange at its top resting `upon andfastenedtosaid ring.

5. In a water heater', an elongated cylindrical casing, a centrally disposed cylindrical sleeve extending upwardly from the bottom of the casing to a level near the top of the casing, lsaid centrally disposed sleeve forming with theside wall of the casing an annular cylindrical water reservoir thereabout, a cylindrical heater housing unit suspended from the top of the casingyand extending downwardly into the central cylindrical sleeve and forming with the interior of the sleeve an elongated annular water-heating chamber of small cross-sectional area, said'housing. stopping short of the bottomof the casing and forming avrelatively small reservoir inthe bottom of the sleeve with saidy waterheating chamber communicating at the top with the rstnamed reservoir and atr the bottom with the second-named reservoir, said second-'named reservoir having a restricted .communication Athrough the wall of the enclosure at a level below the lower end of the heatenhousing, a cold water inlet leading into the casing at a point near the bottom` thereof, and a hot water outlet disposed centrally ofthe bottom of the casing and extending upwardly to a pointabovel-the level yofsaid communicating passage and to a level slightly below the bottom of the heater housing, the top of said casing comprising an inwardly extending flange with a metallic ring mounted thereon and said heater housing having an outwardly extending flange at its top resting upon and fastened to said ring, and a heater element separately insertable into and removable from said housing.

6. In a water-heater, an elongated cylindrical casing, a centrally disposed cylindrical sleeve extending upwardly from the bottom of the casing to a level near the top of the casing, said centrally disposed sleeve forming with the side wall of the casing an annular cylindrical water reservoir thereabout, a cylindrical heater housing unit suspended from the top of the casing and extending downwardly into the central cylindrical sleeve and forming with the interior of the sleeve an elongated annular water-heating chamber of small cross-sectional area, said housing stopping short of the bottom of the casing and forming a relatively small reservoir in the bottom of the sleeve with said water-heating chamber communicating at the top with the first-named reservoir and at the bottom with the secondnamed reservoir, said second-named reservoir having a restricted communication through the wall of the enclosure at a` level below the lower end of the heatel` housing, a cold water inlet leading into the casing at a point near the bottom 5 thereof, and a hot water outlet disposed centrally of the bottom of the casing and extending upwardly to a point above the level of said communicating passage and to a level slightly below the bottom of the heater housing, the top of said casing comprising an inwardly extending flange with a metallic ring mounted thereon and said heater housing having an outwardly extending flange at its top resting upon and fastened to said ring, and a heater element separately insertable into the removable from said housing and comprising a centrally disposed elongated rod, a bottom insulating member fastened to the lower end of the rod, an insulating member fastened to the rod intermediate its ends and at a level above the water-heating chamber and an insulating member fastened to the top of the rod and fastened to said ring independently of the fastening of said housing, said upper insulating members forming a dead air space for insulating the heating chamber against the outside atmosphere.

7 In an electric water heater, a cylindrical casing, a centrally disposed cylindrical sleeve extending upwardly from the bottom of the casing to a level near the top of the casing, said centrally disposed sleeve forming with the side wall of the casing an annular cylindrical Water reservoir thereabout, a cylindrical heater housing unit suspended from the top of the casing and extending downwardly into the central cylindrical enclosure and forming with the interior of the enclosure an elongated annular water-heating chamber of small cross-sectional area, said housing stopping short of the bottom of the casing and forming a relatively small reservoir in the bottom of the enclosure with said water-heating chamber communicating at the top with the firstnamed reservoir and at the bottom with the second-named reservoir, said second-named reservoir having a restricted communication through the wall of the enclosure at a level below the lower end of the heater housing, said heater housing having electric heater elements in the lower part of said heater housing co-extensive with the height of said water-heating chamber, a cold water inlet leading into the casing at a point near the bottom thereof, and a hot water outlet disposed centrally of the bottom of the casing and extending upwardly to a point above the level of said communicating passage and to a level slightly below the bottom of the heater housing, said centrally disposed enclosure being double-walled throughout the length of the wa- .ter-heating chamber and containing a dead air insulating space therein.

8. A Water heater of the character described comprising an elongated vertically disposed water reservoir, telescoping members centrally disposed in the reservoir and forming an elongated annular water-heating chamber thereabout of comparatively small cross-sectional area and forming an auxiliary reservoir beneath the inner of said telescoping members, said auxiliary reservoir being in direct communication with the bottom of the main reservoir through a communicating passage of restricted area as compared with the cross-sectional area of said water-heating chamber and an outlet for hot water leading from said auxiliary reservoir.

9. A water heater of the character described comprising an elongated vertically disposed water reservoir, telescoping members centrally disposed in the reservoir and formingan elongated annular water-heating chamber thereabout of comparatively small cross-sectional area and forming an auxiliary reservoir beneath the inner of said telescoping members, said auxiliary reservoir being in direct communication with the bottom of the main reservoir through a communicating passage of restricted area as compared with the cross-sectional area of said water-heating chamber and an outlet for hot water leading from said auxiliary reservoir, and extending up to a point in said auxiliary reservoir above the level of said communicating passage.

10. A water heater of the character described comprising an elongated vertically disposed water reservoir, telescoping members centrally disposed in the reservoir and forming an elongated annular water-heating chamber thereabout of comparatively small cross-sectional area and forming an auxiliary reservoir beneath the inner of said telescoping members, said auxiliary reser- Voir being in direct communication with the bottom of the main reservoir through a communicating passage of restricted area as compared with the cross-sectional area of said water-heating chamber and an outlet for hot water leading from said auxiliary reservoir and heating means disposed in one of said telescoping members.

11. A Water heater of the character described comprising an elongated vertically disposed water reservoir, telescoping members centrally disposed in the reservoir and forming an elongated annular water-heating chamber thereabout oi comparatively small cross-sectional area and forming an auxiliary reservoir beneath the inner of said telescoping members, said auxiliary reservoir being in direct communication with the bottom of the main reservoir through a communicating passage of restricted area as compared with the cross-sectional area of said water-heating chamber and an outlet for hot water leading from said auxiliary reservoir, said telescoping members containing resilient spacing means therebetween.

12. A water heater of the character described comprising an elongated vertically disposed water reservoir, telescoping members centrally disposed in the reservoir and forming an elongated annular water-heatingy chamber there-l about of comparatively small cross-sectional area and forming: an auxiliary reservoir beneath the inner of saidv telescoplngmemberssaid auxiliary reservoir being in direct communication with the -bottom of 'the main 'reservoir through a communicating passage of restricted area as compared with the cross-sectional area of said waterheating chamber and an outlet for hot water leadingv from ysaid auxiliaryreservoir, an electric heating means disposed in the inner of said telescoping members so as to form an electric heating chamber therein co-extensive with the height of said` water-heating chamber and said inner member having an insulating dead air 'space abovethe heating chamber. 4 y

13. A water heater ofthe character described comprising an elongated vertically disposed Water reservoir, `te'lescoping `members centrally disposed in the reservoir and forming an elongated annular water-heating chamber thereabout of comparatively small cross-sectional area and forming an auxiliary reservoir beneath the inner of said telescoping members, said auxiliary reservoir being in direct communication with the bottom of the main reservoir through ya communieating passage of restricted area as compared with the cross-sectional area of said water-heating chamber and an outlet for hot water leading from said auxiliary reservoir.

14. In a water heater, an elongated cylindrical casing, a centrally disposed cylindrical sleeve extending upwardly from the bottom of the casing to a level near the top of the casing, said centrally disposed sleeve forming with the side wall of the casing an annular cylindrical water reservoir thereabout, a cylindrical heater housing unit suspended from the top of the casing and extending downwardly into the central cylindrical sleeve and forming with the interior of the sleeve an elongated annular water-heating chamber of small cross-sectional area, said housing stopping short of the bottom of the casing and forming a relatively small reservoir in the bottom of the sleeve with said water-heating chamber communicating at the top with the iirstnamed reservoir and at the bottom with the second-named reservoir, said second-named reservoir having a restricted communication through the wall of the enclosure at a level below the lower end of the heater housing, a cold water inlet leading into the casing at a point near the bottom thereof, and a hot water outlet disposed centrally of the bottom of the casing and extending upwardly to a point above the level of said communicating passage and to a level slightly below the bottom of the heater housing, the top of said casing comprising an inwardly extending ilange with a metallic ring mounted thereon and said heater housing having an outwardly extending ange at its top resting upon and fastened to said ring, and a heater element separately insertable into and removable from said housing and comprising a centrally disposed elongated rod, a bottom insulating member fastened to the lower end of the rod', an insulating member fastened to the rod intermediate its ends and at a level abo-ve the water-heating chamber and an insulating member fastened to the top of the rod and fastened to said ring independently of the fastening of said housing, said upper insulating members .forming a dead air space for insulating the heating chamber against the outside atmosphere, said upper insulating members being held in place on said rod by means of nuts screw-threadedly engaging said -rod and engaging the upper 'and lower surfaces of the members.

15. In a' water heater, an elongated cylindrical casing, a centrally disposed cylindrical sleeve extending upwardly from the bottom of the casing to a level near the top of the casing, said centrally disposedsleeve forming with theside wall ofthe casing anannular cylindrical water reservoir thereabout,` a cylindrical heater housing unit suspended from the top of the casing and'extending downwardly into 4the central cylindrical sleeve and forming with the interior of the sleeve an elongated annular water-heating chamber` of small cross-sectional area, said housing stopping short'of thebott'orn of the'casing and forming a relatively lsmall reservoir in the bottom 0f the sleeve with said water-heating chamber communicating v'at --the top with'the first-named reservoir and at'the bottom with the second-named reservoir, said second-named reservoir having a restricted communication through the wall of the enclosure at a level below the lower end of the heater housing, a cold water inlet leading into the casing at a point near the bottom thereof, and a hot water outlet disposed centrally of the bottom of the casing and extending upwardly to a point above the level of said communicating passage and to a level slightly below the bottom of the heater housing, the top of said casing comprising an inwardly extending flange with a metallic ring mounted thereon and said heater housing having an outwardly extending ilange at its top resting upon and fastened to said ring, and a heater element separately insertable into and removable from said housing and comprising a centrally disposed elongated rod, a bottom insulating member fastened to the lower end of the rod, an insulating member fastened to the rod intermediate its ends and at a level above the water-heating chamber and an insulating member fastened to the top of the rod and fastened to said ring independently of the fastening of said housing, said upper insulating members forming a dead air space for insulating the heating chamber against the outside atmosphere, said lower insulating member having embedded therein cross-over terminals to which coiled electric heating units are fastened. v

16. An electric water heater comprising a main casing having an opening at the top, an auxiliary casing suspended through said opening and projecting down into said main casing, said auxiliary casing being supported from the top. of said main casing and a housing disposed about the auxiliary casing and forming therewith an annular heating chamber and a removable electric heating unit disposed in said auxiliary casing and independently supported upon the top of said main casing for removalthereof without removing the auxiliary casing.

17. An electric water heater comprising a main casing having an opening at the top, an auxiliary casing suspended through said opening and projecting down into said main casing, said auxiliary casing being supported from the top of said main casing and a removable electric heating unit disposed in said auxiliary casing and comprising spaced insulator plates with coiled electric heating wires suspended between the plates said electric heating unit being independently supported on the top of the main casing for removal thereof independently of the auxiliary casing.

18. A water heater of the character described comprising a vertically disposed water reservoir,

telescoping members centrally disposed in the reservoir and forming an annular water-heating chamber therebetween of comparatively small cross-sectional area and forming an auxiliary reservoir beneath the inner of said telescoplng members, said auxiliary reservoir being in direct communication with the bottom of the main reservoir through a. communicating passage of restricted area as compared with the cross-sectional area of said water-heating chamber and an outlet for hot Water leading from said auxilary reservoir, said annular Water-heating chamber being in communication at its upper end with the upper part of the main Water reservoir, the thermal circulating path of the Water with the outlet closed being from the bottom of the main reservoir through the restricted passage to the auxiliary reservoir and thence through the annular heating chamber to the upper part of the main reservoir and when said hot water outlet is being used to supply hot water the hot water from the top of the tank being drawn directly through the annular chamber in a reverse direction to the thermal circulation.

19. A water heater of the character described comprising a vertically disposed Water reservoir, telescoping members disposed in the reservoir and forming an annular water heating chamber therebetween of comparatively small cross-sectional area, an auxiliary reservoir which is in communication with the bottom of said annular chamber and in communication with the bottom of the main reservoir through a communicating passage of restricted area, and an outlet for hot water leading directly from said auxiliary reservoir and drawing hot water downwardly from the top of the main reservoir through said annular water heating chamber.

WALTER E. HUDSON.

CERTIFICATE OF' CORRECTION.

Patent No. 2,577 :785' June 5, 19L5.

WALTER E. HUDSON.l

It is lhereby certified that error appears in the yprinted specil'canionv of the above numbered patent requiring correction as fellows.: Page h., first eolumn,y line lil, clim 6, for "the removable" read --and removable-Fl;` andthatv the said Letters Patent should be read with this eorrection therein that the Same may conform to the reciord of .the oase in the Patent Office,k

signed and Sealed this 8th day of september, A. D. 1915.

Leslie Frazer' (S6211) First Assistent Commiseioner of Patents.

colurnlfhl line )41, claim 6, for q'the removable" read --and removable-WL* and.`

CERTIFICATE oF CORRECTION; patent No. 2,577,785- June 5 1%5' WALTER E. HUDSON.

It is Aherebyl certified that error appears in` the printed specification, of. the above numbered patent requiring correction as follows.: Page lli, first that` the said Letters Patent should be read with this orrection therein thatzthlcsame may conform to the record of .the case in the Patent Office;` 'Sigdand sealed this 8th day of September, A., D. 19li5. i

Leslie Frazer (Seal) First Assistant Commissioner of Patentm