US1715007A

US1715007A - Air heater

Info

Publication number: US1715007A
Application number: US223666A
Authority: US
Inventors: Arthur E Reuss
Original assignee: GEN IRON WORKS Co
Current assignee: GEN IRON WORKS Co; GENERAL IRON WORKS Co
Priority date: 1927-10-03
Filing date: 1927-10-03
Publication date: 1929-05-28
Anticipated expiration: 1946-05-28

Description

May 28, 1929. .A. EL-REUSS 1,115,007

' AIR HEATER Filed oct 1927 e Sheets-Sheet 1 M ZZ fif May 28, 1929. A. E. REUSS AIR HEATER Filed Oct. 3, 1927 6 Sheets-Sheet 3 INVEN TOR.

May 28, 1929. A, REUSS 1315;007

May 28, 1929. A. EfREUSS 1,715,007

' AIR HEATER I Filed Oct. 1927 6 Sheets-Stieet 5 /N l/E N TOR.

May 28, 1 929. REUSS 1,715,007

AIR HEATER Filed 001:. 3, 1927 6 Sheets$heet 6 Iig l5; 8

5 a w a v I40 Patented Ma 28,1929. i 1,715,007

UNHTED STATES QFHCE.

ARTHUR E. REUSS, OF CINCINNATI, OHIO, ASSIGNOR TO THE GENERAL IRON WORKS COMPANY, OF CINCINNATI, OHIO, A CORPORATION OF OHIO.

AIR HEATER.

Application filed October 3, 1927. Serial No. 223,666.-

It is the object of my invention to provide line 77 of Fig. 6, and partly broken away. 50 a new and improved heater or furnace in Fig. 8 is a horizontal section of my imwhich the air to be heated is forced to move proved device, taken in the plane of the line inva path reverse to its natural direction of 8-8 of Fig. 6.

movement; further, to provide a novel ar- Fig. 9 is an enlarged sectional detail, taken rangement of passages respectively for the in the plane of the line 8-8 of Fig. 6, partly as products of combustion and for the air being broken away; and, if heated; further, to provide novel forms of Fig. 10 is a horizontal section of. my imwalls and assembling of said walls for formproved device, taken in the plane of the line 10 ing crossing serpentme passages; further, to 1010 of Fig. 6.

provide a novel arrangement of serpentine The fuel for heating my improved heater o passages respectively for the products of comis exemplified as gas, although other fuel, bustion and for theair being heated; further either solid, liquid or gaseous, may be emto provide novel means for m'oistening said ployed. A fire-box 11 has the fuel element 15 air; further, to provide a novel arrangement therein, represented as gas burners 12, proof open-ended crdssing passages and deflecvided with air mixing openings 13, and pro- 5 tors for connecting the ends of neighboring jecting toward each other in pairs for propassages; further, to provide novel means for ducing combined flames, the burners being sealing said deflectors; further to provide a attached to a manifold 14, with which a feednovel arrangement of means for assembling pipe 15 connects, a controLvalve 16 being in the passages and deflectors; and, further, to the feed-pipe. provide novel means for moving the air being The body of the fire-box may be a casting, heated and enhancing the flow of the prodand is exemplified of rectangular form, and nets of combustion. provided with ribs 17 and having open ends,

The invention will be further readily unwhich are respectively closed by

sheets

18, 19.

derstood from the following description and Above the fire-box, passages 21 are shown claims, and from the drawings, in which latrectangular in. cross-section provided with ter upper walls 22, lower walls 23 and side walls Fig. 1 is a perspective view of my im- 24, 25., These passages are open-ended as 301 proved device. shown at 26, 27. The walls form .flat rec Fig. 2 is a perspective view of one come tangular tubes made out of metal sheeting, of the heater, showing the arrangement of the edges of which are connected at 28, as passages and deflectors and means for con, by means of welding. The lower one of these necting the same, partly broken away. passages, designated 29, has side walls 30, 31,

5 Fig. 3 is a sectional view of a detail. shoW- which project downwardly alongside of the ing the blower, taken on the line 33 of Fig. 1.

flanges

32, 33, extending downwardly at the g5 Fig. 4 is a vertical cross-section of a portion respective ends of the fire-box top, the lower of my improved device, taken on the line 44 ends of said side walls and said flanges beof Fig. 1. ing, secured together, as by welding.

40 F" g. 5 is a vertical cross-section of the fire- These passages are arranged one above the box and moistening means'for the air being other in the heater, and are spaced apart by heated, taken on the line 5-5 of Fig. 1, spaces 41, which form passages arranged beand partly broken away. tween and at right angles to the passages 21.

Fig. 6 is a vertical longitudinal section of One of the ends of the top wall of the re- -1 myimproved device, taken in the plane of spective first-named passages 21 is bent away the line 66 of Fig. 7, and partly broken from the passage to form a flange 44 at right away. angles to said top wall and secured to the end Fig. 7 is a vertical cross-section of my edge of the lower wall of the corresponding improved device, taken in the plane of the passage thereabove, as by weldmg, as shown 30 vided with a flange 60. The flange 60 and at 48. The alternate ends of said upper walls sages 21 are reversely bent toward each other, to form flanges 45, (P88 F 1g. 7), to form the other side wall of the passages 41.

- These passages are open-ended as shown at Deflectors or

return bends

51, 52, shown of semi-cylindrical form, connect neighboring passages, 21, 29', such neighboring passages being above one another, at the respective ends of said passages. (See Figs. 7 and 8.) These deflectors are shown formed in sheets 49, 50, and have connecting webs 53,- 54, therebetween, which are connected with the flanges 45, as by means, of welding. The upper wall of the upper one of the first-named passages 21 has upwardly extending flanges 55 at its respective ends. .The deflector sheet 49 has an upwardly extending flange 56. The flange 56 and the flange 55 proximate thereto are fixed together, as by means of welding.

An upper deflector 57 at the other end of the passages 21 forms one wall of an .inletport 58 for said first-named passages. The opposite wall of said inlet-port is formed by a bent sheet 59, having a curvature similar to the curvature of the wall 57, and is prothe flange 55 proximate thereto are connected together, as by means of welding. A lower deflector 61 at the same end of the lower pas sage 29 forms a deflecting wall into an extension 62 for said first-named passages 21. This extension forms 'a passage about both sides and the bottom of the fire-box. The

outer walls

63, 64, 65, of said extension passage are' formed by a sheet'of metal which is parallel with the sides and bottom wall of the fire-box. The upper end of the wall 63 is provided with an outwardly extending flange 66 and the lower end of the lower deflector 61 is provided with a flange67, the flanges 66, 67, being rigidly secured together, as by welding.

The lower end of the deflector sheet 49 is provided with a reverse bend to form a footplate 71, which rests on the top wall of the fire-box, its outer end being formed asa flange 72, which is secured to the upper end of the side wall of the fire-box, as by welding. A sheet 73 extends lengthwise of the heater, its lower end 74 lapping the flange, 7 2 and being secured thereto, as by welding.

This sheet forms the inner wall of the passage extension 75 for the heated air alongside the nest of cross-passages. This pas sage extension forms an extension of the passage 62. The outer wall of this upper end of the.passage extension is formed by a sheet 76, provided with a flange 77 at its lower end, with which a flange 78 at the upper end of the outer wall 65 is complemental, the

flanges

77, 78, being secured together, as by The outer walls of said connecting passages are-formed by said deflectors and the inner wallsthereof areformed by the side walls.

of the cross-passages 41.

The passages 21 extend throughout the major portion of the width of the furnace and, with the connecting passages, form a serpentine passage for the air to be heated. The direction ofmovement of the air in said passages is indicated by the arrows a. The air is received through the inlet port 58 and is exemplified as having a downward course in said passages above the fire-box. forced around the bot-tom of the fire-box and then ascends in the ascending stretch of the passage, and is delivered through the discharge port 81 of said passage.

The air to be 'heatedfis preferably forced in a direction reverse to the direction of natural flew of heated air, which would be upward in the serpentine passage. Theair to be heated is forced downward, as by means of a blower 85, which comprises an electric motor 86 and afan 87 in an intake chamber 88, to which a pipe 89 may lead from a suitable source, as from theoutside air, or the air may be received through said pipe from the house or rooms or space to be heated. A hood 90 is located between the blower'andthe inlet port 58, and directs the air into the and provided with usual dampers 94, direct the heated air to the desired point of use,

as to the variousrooms in the dwelling, or to other spaces to be heated. a

The products Ofcombustion are received" through an opening 101 in the rear wall '19 of the fire-box-or combustion chamber. The respective. upper walls and lower walls of the passages 21 above the fire-box form .respectively the lower wall and the upper wall of the passages 41 crossingly arranged with relation to the first-named passages, the side.

walls of said last-named passages being formed by the bent ends of.the upper and lower wallsof-the first-named passages 21, as hereinbefore explained. 7.) The. ends of neighboringpassages 41 12b 3 (See Figs. "6 and above one another are connected at the respective ends of said passages by means of

deflectors

102, 103, which are formed in

deflector sheets

104, 105, at the respective ends of said passages 41. p

The said sheets are. provided with connectmg webs 106, connected with the side walls of the passages 21 at alternate sides of said passages 21, as by welding. (See,Fig."6.) The other sheet 124 of one of said corner The upper end of the deflector sheet 104 is pieces forms an lend-wall for the deflectors provided with an upwardly extending flange 107 connected with the side wall of the upper 5 first-named passage 21, as by welding. The

lower end of said sheet is provided witha flange 108, connected with the side Wall of the lower passage 21.

The upper end of the deflector sheet 105 is extended as a wall 109 of the outlet-port 110, which wall extends crosswise at the front end of the furnace. The opposite wall 111 of said. outlet-port is formed by a sheet of metal extending crosswise of the furnace, and is provided with an upwardly turned flange-112 connected with the upperside wall of the upper passage 21.

The deflectors are shown curved and form connecting passages 113, 114, between the proximate open ends of neighboring passages 41. The outer walls of said connectin passages are formed by said deflectors and the inner walls thereof are formed by the side walls of the cross-passages 21. A de flector 115 forms the outer wallof a connecting passage 116, which connects with the fire-box. -The innerwall of the passage 116 is formed by the side wall, of the lower air passage 29. The upper and lower ends of said last-named deflector are respectively provided with

flanges

117, 118, secured respectively to the side wall of thelowerpassage 21 and'to the wall 19 at the-lowerside of the opening 101, as by means of welding.

A serpentine passage extending back and forth is thus provided for the products of combustion, the course of the products of combustion being indicated by the arrows b. The products of combustion have a serpen- 40 tine course back and forth between the passagesthi'ough which the air bein heated moves back and forth in a serpent ne path.

The products of combustion are separated from the heated air .by the single thickness of sheet-metal which forms the dividing-wall between the passages through which the products of combustion and the air respectively pass, providing for extreme transferrence of heat to said air.

Theends of the deflectors, the ends of the outlet ports, and the ends of the extension passages for the air being heated are, as thus far described, open. J

The open-ends of the deflectors are at the respective corners of the heater or furnacearranged at right angles to each other, as exemplified in Figs. 2 and 8. Right angular corner-pieces 121' are provided at the corners at one side of the heater.

Each of these corner-pieces comprises a sheet 122, which form end walls for each of the deflectors 52, for the inlet-port 58, and

. the connecting portion 1230f the air passage above the fire-box.

102 and 115. The other of these corner-pieces 121 comprises a sheet 125, which forms an end wall for the other end of each of the deflectors 103 and the outlet-port 110. These respective sheets and Walls are secured together, as by means of welding.

The corners in the angles of said corner pieces are connected with the superposed.

edges of the walls of said

passages

21, 29 and 41, as by 'means of welding.

The outer edges of said corner-pieces are respectively provided with

flanges

126, 127, secured to the

walls

128, 129, 130, of an outer casing 131 for the heater.

The other ends of the

deflectors

102, 115, and the opposite ends of the deflectors 51 at the other side of the heater, and the opposite ends of the upper passage '7 5 of the delivery portion of the heated air conduit are closed by corner-pieces 132.

One of these corner-pieces is provided with a sheet 134, whichis connected to the other ends of the

deflectors

102 and 115. The other of these corner-pieces is provided with a sheet 135, which is connected to the other ends of the deflectors 103 and the outlet-port 110, as by means of welding for closingsaid ends.

Saidcorner-pieces comprise sheets 136 across the ends of the open-ended deflectors 51 and across the ends of the upper delivery portion 75 of the heated air passage, being connected with said ends, as by means of welding to form a tight joint. a

The corner in the angle of said corne pieces is connected with the superposed edges of the walls of the respective passages at said.

corners, as by means of welding.

The outer edges of said corner-pieces are provided with

flanges

137, 138. The flanges 137 are connected respectively with the

walls

128, 130, and the flanges 138 are connected with the wall 139 of the outer casing.

, The corners of said outer casing are preferably rounded, as at 140, for pleasing appearance of the heater. The casing is also provided with a top plate 141 connected with upright walls of the casing by angle irons 142,

as by means of welding. The topplate may also be connected with the upper wall of the upper cross-passage 21 by means of channel plates .143, connected respectively with said wall and said top-plate by meansof welding. All of the joints between the combustion chamber, the passages for the products of combustion and the passagesfor the air are securely made, to prevent passage of the products of'combustion into the air passages, or vice versa, and to prevent a. mixture of the @air to be used for heating and the products of combustion.

\ the fire-box, which are" shown as plates, are

The front wall 18 and the rear'wall 19 of v and rear dle 168.-

secured to the respective ends of said chamber, as by means of welding. These plates are shown as extending to the bottom wall 145 of thecasing. The outer upright walls of the casing are connected to'the bottom wall by means of angle irons- 146, as b means of Welding. The end walls of the re-box and the bottom wall or plate of the casing may be connected together, as by means of angle irons 147 by means of welding. (See Fig. 6.)v

. The bottom wall 64 of the lower cross-' passage of-the air conduit belowthe fire-box is connected at its'respective ends to the respegtive front and rear plates of the fire-box,

as by means of brazing.

The casing may be supported on legs 1.49 shown as angle irons provided with feet. 150, the angle irons being received through the bottom of the casing and secured to the

front plates

18, 19, as by means of weld- The fire-box or combustion chamber is shown provided, with an inlet opening 151, the walls of which are formed by a channel frame 152. 'The front wall of the casing and the front wall of the fire-box are provided with complemental openings, the margins of which are secured to the channel frame, as

by means of welding, A door 153, hinged by.

hinges 154 to the front wall of the casing is provided for said opening. The door is pro- The respective closures comprise an inner wall 165 of a curvature corresponding to the general curvatures of the. deflectors. Outwardly extending walls 166 extend from said inner wall, an outer wall 167 being received across the outer ends of said outwardly ex-' tending walls and forming a box-like structure for the closure, which is. preferably securely closed to form an air-tight cavity in.

the closure, which serves as an insulating space. The closure is provided with a han- "The closure is provided with a marginal groove 169, in which a packingfl'l'ZO is received. The packing'coacts with the outer end. of the wall 162 of theaopening, to form ,a fume-tight seat for said closure. The closure is arranged to be clamped in placeto insure the. sealing of said seat by means of jaws 171 having clamping lugs (see Fig. 9) and pivotally received about screws172 fixed in'the outer wall of the deflector, and having thumbnuts 17 3 received about their outer threadend ends for clamping the closure in place.

The wall of the casing is throughout its inner face provided with a heat insulating lining 175, consisting for instance of asbestos heat-insulating block sheeting. The top space 176 above the upper air passage 21 is preferably a dead-air space, being closed around its edges by means of the channel-pieces 143 and the flanges 55.

In the present constructlon the products of combustion are r'eceivedthrough the crosspassages and .deflec'tors provided therefor,

which cross-passages are exemplified as rectangular in cross-section, extending, back and forth throughout substantially the horizontal cross-sectional area of the heater, and having thecross-passages for the air being heat-.

ed, also exemplified as rectangular in crosssection. extending back and forth crossingly between the same, andextending substantial- .ly throughout the horizontal cross-sectional area of the heater.

Single walls of metal are thus provided by this construction between the passages for the products of combustion and. the passages for the air being heated, enabling substantially.

all of the heat in the products of combustion to be transferred to the air being heated.

The spaces 1.81 162, into which the deflecc tors 51, 52-, for the air being heated, extend are preferably dead-air spaces, being sealed all around,and the

spaces

183, 184, into which the

deflectors

102, 115,-103, forthe products of combustion, extend are also preferably dead-air spaces, being sealed all around. N0 heat is therefore lost .to the outside of the heater. Any heat radiated by any of the lower deflectors into said respective spaces is absorbed by deflectors thereabove. The lower deflectors of the serpentine passage for the products of combustion aid in reheating the products of combustion passing through deioa fiectors thereab'ovefor again transferrin the heat thus absorbed to the air being heate Means are provided for moistening the air. These means are exemplified as an absorbent, pad 189 from which moisture may be absorbed by the air passing the same. This absci-bent pad is shown located below the combustion chamber. The lower wall 64 of the lower cross-passage is shown provided with perforations 190, through which moisture from the absorbent pad may be drawn into I v the lower cross passage 62 by the air passing through the latter. (See Figs. 5 and 7.) The absorbent pad-is preferably separated from the pad of heat insulating material between said lower wall and the lower wall of the cas irons, surrounding the body of'absorbentmaing, as by means of a frame 191 .of channelterial, between said body and the body of I heat-insulating material, and fixed to the lowerwall 64.

Absorbent strips 192 connect with the absorbent pad and depend therefrom, these strips being flexible. The strips and pad are of such materialasto absorb water by capillary attraction. The strips may hang into a body of water in areservoir 193, shown as a drawer sliding in guideways 194 on the bottom wall of the furnace. A plate 195 supports the absorbent pad and is provided with slots through, which the strips, pass. The

plate and absorbent pad and strips are re-' movable by removing the guideway 194.

A pipe 196 extends from the drawer and has a funnel 197 at its outer end. The top of the funnel is at the level of the desired heightof water in the reservoir. The reservoir is arranged to be filled through the funnel. The desired height of the reservoiris indicated by the water in the funnel remaining at the height of the top of the funnel. The pipe 196 and funnel may be used as a handlefor the reservoir. When the reservoir is moved in or out its rear and front walls respectively pass under the depending strips, which strips flex out of the way of said walls. When the reservoir is pushed inwardly the strips will automatically position themselves in the body of water in the reser- V011.

The outlet-port connects with a hood 201, from which a flue202 extends.

If it should be found, in the installation of the heater, that the heatremaining in the products of combustion passing from the heater is not sufiicient to cause natural rise thereof in the flue, the outward movement of said products of combustion maybe supplemented by an artificial draft obtained from the blower.

As an exemplification of this, the hood 90 may be provided with a pipe-203,.connecting said hood 90 with the flue, the latter connection being preferably at a point above a damper 204: in said flue. (See Figs. 1 and 3.) A gate 205 is adjustable to regulate the passage of air through said pipe or to entirely close the same. The gate is connected with a handle 206 for operating the gate. The damper 204 regulates the passage of roducts of combustion in the flue but prefera ly does not close the flue.

In order to take care of condensation in the products of combustion, the upper portion of the serpentine passage for the products of combustion is provided with a depression 207 which is shown in the wall 109. The condensation in the products of combustion collects in said depression and is dischargedthrough a pipe 208 to a suitable point outside of the heater.

' The sheets, angle irons, channel irons and other parts of the heater, except otherwise specified,'may be made of metal, and all permanent joints may be suitably made, as by welding. The fines or passages above the fire-box form a stack of crossing tubes which are rectangular in cross-section and rigidly 7 of combustion and for air being heated, and

a pair of series of deflectors at the ends ,of said respective series of passages, said deflectors-connecting neighboring ones of said respective series of passages for forming crossing serpentine passages, said deflectors provided with connecting webs at the inner a pair of series ends of said deflectors connecting superposed deflectors, and means securing said webs of the deflectors for each of said series of passages to the Walls of the other of said series of passages with said deflectors extending outwardly from said walls.

2. An air heater comprising a pair of series of crossing passages respectively for products of combustion and for air being heated, and a pair of series of deflectors at the ends of said respective series of passages, said deflectors connecting neighboring ones of said respective series of passages for forming crossing serpentine passages, said deflectors provided with connecting webs at the inner ends of said deflectors connecting superposed deflectors, means securing said webs of the deflectors for each of said series of passages to thewalls of the other'of said series of passages with saiddeflectors extending outwardly from said walls, and means for orcing the air being heated through its passage in a general direction which is downward.

3. An air heater comprising a pair of series of crossing passages respectively for products of -combustion and for air being heated, said crossing-passages substantially rectangular in cross-section, the upper walls of one of said series of passages forming the lower walls of the other of said series of passages, and the ends ofsaid walls of one of said series of passages bent to form the sides of-the other of said series of passages, and a pair of series of curved deflectors at the ends of said respective series of passages connecting neighboring ones of said respective series of passages forming deflecting passages of substantiallythe same cross-sect onal areas as thecrosssectional areas of said respective series of passages, superposed deflectors of said respec- .tive series of curved deflectors connected by webs integral with said deflectors, means securing said webs of said deflectors for each of said series of passages to the walls of the other of said series of passages, said series of I passages and said deflectors forming cross ing serpentine passages.

, ation of said deflector at said opening.

I ranged, a pair of series of deflectors at the sages between said neig boring passages ucts of combustion and for air being heated in said last-named serpentine passage in a 1 ing a current of air into said flue to assist the heated air, a passage communicating with said condensation from and heat insulating material along the inner and said crossing serpentine passages, said said serpentine passage for the air bemg heat- -edhaving an upper end, a blower communisaid serpentine passage forsaid. products of eating therewith for vforcing movement in sa1d\1ast-named serpentine passage in a dig-pipe connectlngwith said depression-and excurrent of air into said flue to assist the natural flow of the products of combustion, means for controlling the flow in *said last named passage, and a damper in said flue, and said last-named passage connecting with said flue above said damper.

4. An air heater comprising a pair of series ofcrossing passages, said passages comprising side walls, a pair of series of deflectors at the ends of said respective series of passages connecting neighboring ones of said respective series of assages and forming connecting passages etween neighboring passages of said series about the side walls of lntermediate, passages, forming serpentine conduits respectively for products of combustion and for air being heated, a casing outside said deflectors, a deflector of said serpentine conduit for said products of combustion provided with an opening, a wall for said opening connecting with said casing outside said deflector, and a closure forsaid opening in said wall, said closure provided with an inner wall which forms a substantial continular in cross-section arranged one above the other and havlng spaces substantially recflues provided with flanges at their ends and closed at their sides, the upper and lower walls of said flues forming the lower andupper walls of said spaces, said flanges of said flues bent to form'side walls for said spaces which thereby form flues at substantial right angles to said first-named flues, and deflectors connecting neighboring ends of said respective flues for forming crossing serpentine passages respectively for the products of com- 5. An air heater comprising a pair of series I of passages having sid wall ro ing-1y are recting the products of. combustion and the air in alternate paths in crossing directions.

9. In a heating device, the combination of a plurality of rectangular flues arranged one above the other and having rectangular spaces therebetween, said flues provided with flanges at their respective ends and closed at their sides, the upper and lower walls of said flues forming the lower and upper Walls of said spaces, said flanges of said flues bent to form side walls for said spaces to provide flues at substantial right angles to said first-named flues, and thereby forming a stack of crossing flues having closed sides alternately superposed at the four sides of said stack, and a ends of said respective series of passages connectlng neighbormg ones of said respectlve series of passages forrnm connecting pasabout the sides of intermediate passages, said deflectors extendin outwardly beyond said side walls and wit said passages forming crossing serpentine passages respectively for the products ofcombustion and for the air being heated, a casing outside said'deflectors,

face of 'said casing, there being adead air space between said heat insulating'material bent portions forming deflectors and intermediate webs integral with said'deflectors, said deflectors respectively encompassin neighboring ends and intermediate close sides, and means attaching said webs of said sheets .to said closed sides for forming crossing serpentine passages respectively for the products of combustion and for the air being heated 10. An air heater comprising an inclosing casing a pair of series of crossing alternating superposed passages respectively for products of combustion and for air being heated, and a pair oi series of deflectors at the ends of said respective series of passages, said deflectors connecting neighboring ones of said respective series of passages for forming deflectors extending into said dead air space. 6. An air heater comprising a pair of crossmg serpentine passages respectively for prod:

said serpentine passage for said products of combustion having a flue at its upper end,

eating, therewith for forcing movement of air direction reverse to -the natural flow of said heated air, and a passage communicating with said blower and said flu'e for introducnatural flow of the products of combustion. 7 An air heater comprising a pair of crossing serpentine passages respectively for products of combustion and for air being heated,

combustion having a flue at its upper end, sald serpentine passage for the air being heat tion of saidserpentine passage for said proded having an upper end,"a blowencommuniucts o f'combustion provided with a depression in said casing for condensation, and a rection reverse to the natural flow of the tending to outside said casing for draining said blower and said flue for introducing a Outside Said w g 8Q In a heating device, the combination of a plurality of flues substantially rectangu tangular in cross-section therebetween, said Inustion and for air being heated and for disheet at eachiof said sides having outwardly said depression to 11. An air heater comprising a pair oi? series of rossing serpentine passages respectively for products of combustion and for air being heated, a blower communicating with 5 said serpentine passage'for said air being heated for forcing movement of air in said last-named serpentinepassage, and a passage communicating with said blower and hav ng connection with saidserpenti'ne passage for said products of combustion. for assisting the 1 naturalfiow of the" products of combustion through said last-namedserpentine passage.

In testimony whereof, I have hereunto signed my name.

ARTHUR n. REUSS.