US1991280A - Electric heater - Google Patents

Description

- L. P. HYNES ELECTRIC HEATER Filed Dec. 1, 1930 5' Sheets-Sheet 1 m. '12-, was. L. P, was r 1,991,280-

ELECTRIC HEATER Filed Dec. 1, 1930 5 Sheets-Sheet 2 Feb. 12,1935.

L. P. HYNES ELECTRIC HEATER 4 Filed Disc. 1. 193 0 5 Sheets-Sheet" 3 I Feb. 12, 1935. I L. P. HYNES 8 ELECTRIC HEATER Filed Dec. 1, 1930 5 Sheets-Sheet l irln a.

Patented Feb. 12, 1935 1,991,280

UNITED STATES PATENT OFFICE ELECTRIC HEATER Lee P. Hynes, Philadelphia, Pa. Application December 1, 1930, Serial No. 499,368

28 Claims. (Cl. 219-39) This invention is an electric heater of the type ance with the invention. Figure 2 is a diagramwherein heating elements are located within a matic sectional view. Figure3 is a diagrammatic casing, through which air is forced by a fan, so as front elevation illustrating a novel form of electo insure a circulation of heated air. trical heater. Figures 4 and 5 are similar views 5 In the operation of electric heating apparatus illustrating a modified form of heater. Figure 6 5 of the type above mentioned, there is always danis a diagrammatic perspective view illustrating ger that the heater will destroy itself by building the circulation of the air through the heater. up a destructive temperature, if the fan for any Figures 7, 8 and 9 are diagrammatic views illusreason fails to operate. One of the objects of the trating a modified system of air circulation. Figinvention is to overcome this objectionable conures l0 and 11 are diagrammatic views illustratdition, by providing safety means for automatiing other modifications of the heating de cally shutting off the current to theheater, if for Figures 12 and 13 are diagrammatic views illusany reason there is a failure of the motor circuit trating the heater and fan circuits for three Phase or an undue rise of temperature within. the heatand single ph e m r p c v y, W the ing chamber. safety control means applied thereto. Fig. 14 is 15 With a three phase motor, it is undesirable to a Similar V illustrating a fi d c u put the motor circuit through the usual emer- Referring to the drawings, and particularly to gency fuse, commonly placed in the heater circuit Figures 1 and 6, 15 designates a casing which may as a last resort protection. This is because it is be constructed of any Suitab e 01" desired matenot good practice to allow the heater to build up i and p v d'wi a motor chamber 16 a d a excessive temperatures within the casing, to the heating C er e o t 0! the met degree necessary to blowthe heat fuse. In other chamber is closed by a suitable cover 18, which is words, the heat fuse should be an emergency feashown broken away in Figure The front W ture of last resort, in case all other safety factors of the heater chamber is provided with an outlet fail, and therefore not utilized in any other way. Opening 19, and the wall between the two fl Aside from this, however, there are conditions bers is'provided with an air inlet opening 20, which might damage the motor, but which would through which th Shaft 01 motor M e 50 not be prevented by any form of temperature fuse 8-8 to ot ab y S ppo e fan blower F, Withlocated in the heating chamber. For instance, in chamber 7- Air e ers e ca 15 through some external fuse on the line might blow, or some e p ning 21 o d in the space above the loose connection might produce a single phase hea r cha ber a d P ss through the condition on the three phase motor, in which motor chamber 16 is introduced into the heating event the motor would be damaged and burned c ambe th ou he Op 0 (See Figure out, unless the circuit was cut 011 in a short time. It will be noted that a certain amount of the radi- 30 In view of the above, a further object of the ated heat from the heating elementsisinterceptinvention is to provide a safety control, not ded by t e Wa be the Chambers, and a pendent upon the heat fuse normally employed mitted by said wall to the ir W hin the h mas a final safety factor, but so constructed and her 16 before it passes to the heating chamber arranged that the circuits to theheater and to throu h e Opening The Said Well also Serves the motor will be automatically broken, in-the to protect the motor from the radiant heat.

event of a failure of the motor circuit, or an over- Any preferred form of electrical heater may be heating of the heater coil, or both. A further employed, but a desirable form is illustrated in object is to provide a heater of the character men- Figures 2 to 5, both inclusive. Referring to said tioned equipped with a heater of low storage cafigures, e fan F is Placed Within the usual yp pacity, so that the normally employed heat fuse 0f Sc o easing provided with an Outlet P may be placed close to the heater coils, and set g 6, y registering With the Outlet Open? at a relatively small margin above its normal temi g 19 of the casing, the inlet opening 20, above perature, thereby insuring much better protecmentioned, being in the side of the casing. Lo-

tion. A further object is to provide a simple and cated inside of the scroll casing 25 are heating novel form of heater. elements 27, which, in the forms illustrated in The invention will be hereinafter fully set forth Figures 2 and 3 each consisting of a plurality of and particularly pointed out in the claims. flat electric heater elements arranged edge to In the accompanying drawings: edge in parallel relation, in such manner as to Figure 1 is a perspective view illustrating an conform to the contour of the inner surface of electric heating apparatus constructed in accordthe scroll casing 25, and also to partially encircle Q the periphery of the fan F. In operation, as the fan is revolved by the motor, air is drawn in through the opening 20, and is then thrown outwardly at all points by the centrifugal force, so that the outthrown air will impinge upon the heating elements and become heated, being finally driven out through the opening 26. By placing the thin heating elements 27 around the inside of the scroll, they are exposed to the direct impinging air current and rapidly heat the air In the form illustrated in Figures 4 and 5, the heating elements 27' are similarly arranged fiat units, supported by suitable arms 28, within the casing 25, and concentric with respect to the fan 1''. By means of this arrangement, the fan causes air currents to move in a radial direction between the heater elements and in contact with the heated surfaces thereof, before being discharged into the atmosphere.

An advantage of either type of heater thus far described is that the heating elements radiate a considerable amount of heat into the fan wheel itself, because radiant heat is not absorbed directly by the air. All of the radiant heat that escapes from the internal curve of the heater elements strikes directly toward the center, into the rapidly moving fan wheel, which becomes an ideal medium for transferring the heat to the air, because the wheel has every portion of its exposed area under a maximum frictional contact with the air travelling through the heating chamber.

In the modifications illustrated in Figures 7, 8 and 9 the casing 15' is divided into the motor chamber 16- and heating chamber 17, but the wall 30 between said chambers is closed, except for an opening just large enough for the passage of the motor shaft. The motor, fan and heating elements may be arranged according to any of the forms described in connection with the preceding figures. In Figure 7, however, the heating means is shown as consistingof a plurality of parallel circular disks having central openings through which the fan extends. The disks are laterally spaced with respect to each other but axially with respect to the heater chamber, so that their flat surfaces are radially positioned with respect to the fan shaft. In Figure 8 the heater elements 2'1 are of the same type as those illustrated in Figures 2 and 3.

As will be more readily understood from Figure '7, the heating chamberl'l is located between the motor chamber 16 and an air circulating chamber 31, which connects the motor chamber 16 by a passage 32. The wall between the circulating chamber 31 and the heating chamber 17' is provided with an opening 33 through which air is introduced into the heating chamber. By this arrangement, the air enters the motor chamber 16 and passes around the heater chamber through passage 32 to the chamber 31, and thence through opening 33 into the heating chamber. The heated air is expelled in the usual way, being preliminarily heated before it enters the heating chamber. By this arrangement, a highly satisfactory transfer of heat at low heater temperatures is accomplished, because it allows-a concentrated heat source without wasting space. The forms of heater thus far described also have the advantage that the fuse X, normally placed in the heater circuit, as a safety factor, may be placed within the casing which houses the various parts. It should also be observed that the heating elements 27, which are shown in Figures 2 and 3 as forming a lining for the inner surface of the scroll casing 25, are shown in Figure 8 as themselves constituting the scroll without the surrounding casing 25.

In Figure 10 is shown another modified form of heater for attachment to ceilings, or other overhead supports. In this form the heater chamber 35 is formed of a suitably shaped casing depending from an air supply chamber 36 of larger diameter, suspended from a ceiling or other support in any desired manner. The motor M is also suitably supported so that one end extends through an opening 3'7 in the top wall of chamber 36, which is spaced from the ceiling, as shown. The fan F is mounted on the motor shaft and positioned to operate within the heater chamber 35. The heater consists of a plurality of annular heater elements 40 and 41 arranged concentrically with respect to each other, and with respect to the axis of the motor shaft, being spaced apart so that air circulated by the fan may pass between the respective heater elements. In other words, the surfaces of the heater units extend parallel with each other and with the axis of the fan, the element 41 in eifect constituting an annular wall of a heating chamber which is located concentrically around the fan. It will be observed that the elements 41 are positioned so as to enclose the fan, while the elements 40 are positioned below the fan. The heaters 40 may be omitted without departing from the spirit of the invention. In operation, air is drawn through the opening 37 and also through the peripheral space 38 between the chamber 36, and the heater ring 41, and is discharged downwardly in a manner which is obvious from the drawings. A suitable screen 39 covers the lower part of casing 35. The upper wall of chamber 36 is so positioned as to intercept radiant heat from the heating means within the chamber. A two-fold result is thereby obtained, first, to protect the motor from the radiant heat of the heating ele ments, and second, to pre-heat the air flowing over and in contact with said wall, before it passes through the opening 3'7 into the heater chamber. By surrounding the fan with the heater means 41, radiant heat is also transmitted to the fan and transferred thereby to the air current passing through the heating chamber. It is to be understood that Figure 10 is purely diagrammatic, and no attempt has been made to illustrate the details of structure by means of which the various parts are supported, it being obvious to those skilled in the art that this may be done in various ways.

In Figure 11 is another modification in which additional heating elements 42 are placed within the inner chamber 43 leading'to the fan chamber 44. By this arrangement, the air is heated as it is drawn into the fan chamber. a

It will be noted that in the forms illustrated in Figures 1, 6, 7, 8, 9 and 10, the various chamber walls around the heater are naturally heated by the radiant heat thrown out by the heater units which are exposed within the heating chamber, so that the air entering the fan chamber or heating chamber is pre-heated by passing over and in contact with said walls before being drawn into the heating chamber. In each instance, the fan is also heated by radiant heat from the heater units, and a part of this heat is also transferred to the air stream as it sweeps over the fan blades.

Referring to Figure 12, the motor M is of the three phase type. The lead-in wire a, which is connected with a suitable source of energy is provided with a branch b which leads through a fuse c to a manual switch d. located within a suitable control box diagrammatically illustrated. Included in the heater circuit is a standard type thermostat e, which is connected with the switch d, so that while said switch is in circuit closed position, the thermostat will control the circuit. From the switch it a conductor f leads through a standard type of heat fuse g to protect the heater circuit, and thence by a conductor it through the safety switch 2, to the coil 7' which forms part of an electromagnetic device controlling switches n, n and 11.2, the functions of which will be later described. A wire it leads from the coil 7' to the outlet terminal I.

The terminal a is also connected by means of the switch n with the heater through wire 0, the return wire p leading to the outlet terminal I through switch 122. The terminal m is connected by the switch 11. to the heater through the conductor q, and the return is also through wire p, switch n2 and terminal 1. The-arrangement is such that while current is passing through the magnetic coil 1, the switches 11, n and 11.2 are maintained in circuit closing position, against the tension of springs tending to open them, so

that the heater is in circuit with the source of energy.

The conductors q and o are also connected by branch wires r and t respectively, with the motor M, the return being through wire 8, which connects with the conductor 2), and through the switch n2 to the terminal I. The branch wires 1' and t are provided with thermally responsive devices T, which control the operation of the safety switch i, and through said switch the magnetic coil 1'. Any preferred type of thermal control safety device may be employed, but it is preferred to use a well known thermal overload relay device now on the market and illustrated conventionally in Figure 1 of the drawings. In this device the thermal overload relay is of the melting alloy type having a mica insulated heating element of nichrome wire or ribbon. The alloy is contained in a cup or cylinder 45 back of the heating element into which the stem of a control ratchet 46 extends. This ratchet normally engages a reset bar B, which is connected to the safety switch 1'. Said bar is normally under spring tension tending to move the bar and the switch in a direction to open the circuit, and the ratchet is arranged to normally hold the bar in a neutral position against the spring tension. When an overload occurs, the thermal unit gradually rises in temperature finally melting the alloy and allowing the stem of the ratchet wheel to turn, releasing the reset bar B, so that the spring tension applied to said bar will cause it to move the switch i to'the circuit breaking position, thereby deenergizing the coil 7' and permitting the switches n, n and n2 to move to open circuit positions.

In operation, with the circuit closed through the switch d, the device is of course under the control of the thermostat e, so that the operation of the motor is governed by the temperature of the room. If, however, the motor should stop for any reason, as for instance the blowing of an external fuse on the line, or some loose connection, or a break in one of the conductors, a condition would be created which would throw the motor out of operation, whereupon the tendency of the,

heater is to build up the temperature to a destructive point. In a short time the heater temperature builds up sufficiently to melt the alloy, and thereby releases the bar B, thereby efiecting the opening of all circuits. After repairs have been made or the defective condition otherwise corrected, the thermal alloy having cooled, the switches may be reset by moving the bar B back until it is reengaged by the ratchet.

In Figure 13 thesame thermal control is shown as applied to a single phase motor. In this arrangement the terminal a is connected through the fuse c and wire b, with the switch d and and thermostat e., fuse element 9, and return wire h, safety switch i, magnetic coil 7", wire In, and terminal I, all in the same manner as the corresponding parts in Figure 11. The terminals a and l are also connected by switches 11.3 and n4, the switch n4 controlling the return from the heater. The thermal relay element T is connected with the switch 113 by means of a wire leading to the motor, both the motor and the heater circuits returning through the switch n4 and the terminal I. The operation of the parts is identical in the two systems, the only difference being in the number of poles in the control and the number of wires to the heater.

In the form of the invention illustrated in Figure 14, the lead-in wire a, branch b, fuse 0, manual switch d, thermostat e, conductor f, fuse g, return conductor h and terminal I are the same as in the form illustrated in Figure 12. The conductor h is connected with the terminal Z through a magnetic coil u, conductor 12 and switch n2. The terminal a is also connected by a conductor w, switch a: and conductor y to one of the coils of the heater H, the return being through conductor z, switch x2 and conductor .2 to the terminal I. In a similar manner the terminal m is connected by a conductor w, switch 0: and conductor 11' to another coil of the heater, the return being through the conductor z, switch .22, conductor a to terminal I. It will be observed that the magnetic coil it controls the operation of the switches a", 1: and 022, so that while said coil is energized the circuit is closed to the heater, and upon deenergizing of said coil the-circuits to the heater are automatically broken. It will also be observed that the coil u is controlled by the switch n2.

In addition to the thermostat and hand switch above described, a second thermostat e2 and hand switch d2 are provided, for controlling the circuits to the fan motor M. The switch d2 is connected with the terminal a by a conductor 02, and the thermostat e2 is suitably connected with the switch d2 in an obvious manner. Leading from the switch d2 is a conductor f2, connected by a safety switch 2 with one terminal of a magnetic 3 coil 1'2, the other terminal of said coil being connected by wire 102 with the terminal I. Said coil controls switches n, n and n2 in a manner similar to the control described in connection with Figure 12. The switch n connects the terminal a, by means of conductor t with the motor M, the return being through wire s, switch 0:, wire w and terminal I. The terminal m is connected by switch 11., through conductor t, with the motor M, the return being through wire s, switch n2 to terminal I. The thermally responsive devices T are placed between the switches 11., 11. respectively and the conductors r and t respectively, the control device including the reset each one is controlled a separate thermostat or by a separate hand switch, as desired. It

will be observed, however, that under no conditions can the heaters receive current unless the motor is running, but that on the contrary, the motor and the Ian may run without heat. This will appear from the operation which is as follows:-

The thermostat e is preferably placed at the heater inlet and may be set for any desired temperature, and controls its circuit in the same manner as described in connection with Figure 12. The thermostat oil is located in the room where a uniform temperature is to be maintained, and operates at whatever temperatures it is set for, to stop and start the fan, by energizing or deenergizing the coil 1'2, as the case may be. L the room temperature drops to the predetermined minimum, assuming the switch dii to be closed, the circuit is closed so that current flow is from terminal a, conductor it, {use lp, conductor c2, switch dli, thermostat c2, conductor 12, safety switch coil 9'2, conductor k2 and terminal 2. The closing of this circuit energizes the coil :2, thereby closing the switches a, n and n2.

While the circuit is closed through the switches n, n, 112, a branch circuit to the heater is also maintained from terminal a by means oi conductor w, switch 3:, and conductor 1/, the heatcand returned by conductor 2, switch r2, conduc-- tor z to terminal I. At the some time, the ter minal m is connected with the heater by means of conductor is", owltol'l :r, conductor 11 and returned through conductor a, switch 2:2, conductor to terminal I.

lrihould the temperature rise above the prede termincd medium in the vicinity of the fan, the circuit will be broken by the thermostat e, thereby deenergizing the coil 2;, and permitting the switches .r, :2 and mil to automatically move to open circuit positions, thereby shutting on all current flow to the heater. The fan motor, however, is unaffected by this operation. Again, assuming that the fan motor and the heaters are normally operating with all the circuits closed, if the room temperature rises to a predetermined normal position the thermostat c2 operates to break the circuit throu h the coil 9'2, and deencrgizing 0! said coils permits the automatic breaking of the circuits through the switches n, 1! and n2, thereby opening the circuits to the heater coils. As soon as the circuit is broken at switch 112, the coil 0 is deenergized, thereby permitting the switches as, x and .122 to move to circuit breaking positions, thereby opening the circuits to the fan. Assmning the parts to be in normal operating positions with the circuits closed, it there is an overheating, such as efiects the operation of the thermally responsive control, the bar B will break the circuit by moving switch 2 to open circuit position, thereby deenergizing the coil 9'2 and breaking the circuits at switches 1t, 11. and n2. The moving of the switch 112 to open circuit position automatically deencrgiscs the" coil 14. and breaks the circuiis to the heaters through switches :r, :r and :22.

What I claim isz 1. In an cle c heater, a fan chamber Wall formed of a ty of flat members, each morn- "lui arraiiigcd as u. some t of the other units, 11 rrrrnged laterally with i other and axially with respect to respect to en the chamber.

2. In an electric heater, a fair chamber wall formed of a plurality of hot members. each morn her being constructed and arranged as a com plete heater unit independent 01 the other units, said units being arranged edge to edge and in perallel relalton.

3. In an electric heater, a fan chamber wall formed of a plurality of flat m be" each memher being constructed and a as a corn plete heater unit independent ither units, said heater elements being arranged laterally with respect to each other and axially with respect to the chamber, said heating elements being provided with exposed flat surfaces so positioned to reflect heat radially into the chamber,

4. In an electric heater, 2. Ian chamber wall provided with a plurality of parallel flat annular heating elements arranged in concentric relation, said heating elements being also arranged laterally with respect to each other and axially oi the chamber.

5. In an electric heater, a fan chamber wall formed of a plurality or flat electric heater ciemerits arranged in parallel relation, said heater elements being arranged laterally with respect to each other and axially with respect to the chamber, and means constructed and arranged to control the now or conducted and radiant heat to an air stream traveling over both surfaces or said wall.

6. In an electric heater, a tan chamber well formed of a plurality oi iiat electric heater elements arranged edge to edge and extending in lines parallel to the direction or air iiow through said chamber.

7.11 on electric heater, a casing having it H heating chamber, a plurality oi parallel at heater elci'zionts within said chamber, said iii-eating elements being arranged laterally with l'espect to each other and axially with respect to the chamber, in such manner to provide a fan chamber, a an within said fan chamber, a motor within said casing, and a wall in said heating chamber located between the motor and the heating elements so as to intercept radiant heat which tends to pass to the fan motor.

8. In an electric heater, a casing having a fan chamber wall provided with a plurality of perallel electric heater units concentric with the axis of the fan, said heater units being arranged latorally with respect to each other but axially or the chamber, a. fan within said chamber, a motor for said Ian, and a wall interposed between the Ian and the motor and positioned to intercept radiant heat.

9. In an electric healer, a. casing, a tan chamber within the casing, parallel flat electric heater elements within said Ian chamber, said heating elements being arranged laterally with respect to each other but axially with respect to the chamber, and also constructed and arranged to heat a portion 0! the chamber wall by radiation, a blower located within said fan chamber, a motor Ior said Ian, and means within said casing constructed and arranged to direct a stream of air over the heated surface of the Ian chamber, and thence through the Ian chamber in direct con tact with said heater elements.

10. In an electric heater, a casing, a fan ohms bcr within the casing, a plurality or :ilat par lei electrically heated air directing mom thin the fan chamber, said heater members being arranged laterally with respect to each other but axially with respect to the chamber, and also constructed and arranged to heat a portion of the chamber wall by radiation, a blower located within said fan chamber, a motor for said fan, and means within said casing constructed and arranged to direct a stream of air over the heated surface of the fan chamber and thence through the fan chamber in direct contact with said heater elements.

11. In an electric heater, a casing, a fan chamber within the casing, a plurality of flat heater elements surrounding said fan and arranged in parallel relation, said heater elements being arranged laterally with respect to each other but axially with respect to the chamber, and also constructed and arranged to heat a portion of the chamber wall by radiation, a blower located within said fan chamber, a motor forsaid fan, and means within said casing constructed and arranged to direct a stream of air over the heated surface of the fan chamber and thence through the fan chamber in direct contact with said heater elements.

12. In an electric heater, a casing, a fan chamber within the casing, laterally spaced fiat heater elements within said fan chamber, said heater elements being arranged laterally with respect to each other but axially with respect to the chamber, and also constructed and arranged to heat a portion of the chamber wall by radiation, a blower located within said fan chamber, a motor for said fan, and means within'said casing constructed and arranged to direct a stream of air over the heated surface of the fan chamber and thence through the fan chamber in direct contact with said heater elements.

13. In an electric heater, a casing, a fan chamber within said casing, a plurality of parallel electric heater elements within said fan chamber, said heater elements being arranged laterally with respect to each other but axially with respect to the chamber, .and also'constructed and ar-- ranged to heat a portion of the chamber wall by radiation, a blower located within said fan chamber and positioned to be heated by radiation from said heater elements, a motor for the fan, and means within said casing constructedand arranged to direct an air stream over the heated surface of the fan chamber and thence through the fan chamber in direct contact with said heater elements and said fan.

14. In an electric'heater, a casing, a fan chamber within said casing, a plurality of flat parallel heater elements within said fan chamber, said heater elements being arranged laterally with respect to each other but axially with respect to the chamber, and also constructed and arranged to heat a portion of the chamber wall by radiation, a blower located within said chamber, a motor for said fan, means within said'casing constructed and arranged to direct an air stream over the heated surface of the fan chamber, and thence through the fan chamber in direct contact with the heater elements, and a shield interposed [between the heating elements and the motor and positioned to intercept radiant heat from said heater elements.

15. In an electric heater, 9, scroll-shaped chamber for a centrifugal fan having its periphery formed of a plurality of fiat members, each member being constructed and-arranged as a complete heater unit independent of the other units, said units being supported edge to edge and interposed between the side walls of the chamber.

16. In an electric heater, a casing, a fan mounted to rotate within said casing, a plurality of flat parallel annular electric heater elements located within said casing and concentric to the 17. In an electric heater, a fan chamber having a curved wall constructed of thin flat heater strips arranged in parallel relation to direct the air flow, an air intake chamber, a motor within said intake chamber, and means constructed and arranged to direct a flow of cool air over the motor, the outer surface of the curved fan chamber and into the fan chamber on the side opposite the motor and then around the inside of the fan chamber wall to an outlet.

18. In an electric heater, a casing, a wall composed of thin curved flat heater members dividing the easing into chambers, a rotor within the inner chamber having surfaces exposed to radiant heat from said wall and adapted to create an air stream, and means constructed and arranged to direct the air stream from the other chamber over the outside surface of the electrically heated well, over the surface of said rotor, then over the inside surface of the electrically heated wall.

19. In an electric heater, a casing, a heating chamber'within the casing formed of a scrollshaped wall composed of thin fiat heater strips arranged in parallel relation, a centrifugal fan wheel within said heating chamber, a partition within the casing spaced from the surface of the heating chamber at a position to intercept radiant heat therefrom, and means cooperating with said fan and constructed and arranged to force an air stream over the exterior of said heater strips and to cause the air stream to then pass over the inside surfaces of said heater strips.

'20. man electric heater, a casing, a heating ,chamber'within the casin the wall of which is constructed of a plurality of thin fiat electric heating members arranged in parallel relation, a centrifugal fan wheel in heat-receiving proximity to said heating members, partitions within said casing spaced from the heating members and positioned to direct the'flow of an air stream through said casing, said partitions being so positioned that the air stream will absorb heat therefrom.

21. In an electric heater, a casing, an internal fan chamber of scroll shape, the wall of which structed and arranged to intercept radiant heat rays and to conduct their heat energy into the air stream. I

22. In an electric heater, a casing, annular flow directing partitions composed of flat parallel electric heating elements and forming a fan chamber, a fan within said chamber, a motor for said fan, said motor and said fan being concentric to the axis of the annular members, and means constructed and arranged to direct an air stream over both sides of the heating members and the interior walls ofsaid casing.

23. In an electric heater, a casing having an inlet chamber, a heating chamber provided with parallel walls formed of annular flat electric heater elements, a fan within said heating chamber. means constructed and arranged to direct the air flow over both sides of each wall, means to intercept radiant heat and to convey it to the air stream, and means to heat the air before and after passing the Ian wheel.

24. In an electric heater, a casing having an air chamber and a heating chamber in communication with each other, a fan within the heating chamber, and electrical heating means also within the heating chamber, said heating means being spaced from and surrounding the fan, said heating means and said fan being so relatively positioned, constructed and arranged that radiant heat emanating from the heating means is absorbed by the fan and transferred by the fan to the air stream passing through the chambers.

25. In an electric heater, a heater chamber having an air inlet opening in one wall thereof, a motor positioned outside of said chamber and having a shaft projected through said opening, a fan mounted on said shaft and located within said chamber, and heating means within the chamber and so positioned as to surround the fan, said heating means and said wall being so relatively positioned, constructed and arranged that radiant heat from the heater means is intercepted by said wall and transmitted to the air flowing in contact with said wall and entering said chamber through said opening.

26. In an electric heater, a chamber having air inlet and air outlet openings, a motor located outside of the chamber and having its shaft extended into the chamber, a fan mounted on the motor shaft and located inside of said chamber, a plurality of thin flat circular heater rings supported within the chamber in positions parallel with each other and concentric to the fan, and a wall positioned to shield the motor from radiant heat emanating from said heater rings, said fan, said heater rings and said shield being so positioned, constructed and arranged that air flowing through said chamber will pass radially over the surfaces of the heater rings and also pass over other surfaces which are heated by radiant heat, so as to conduct the radiant heat into the air stream.

27. An electric heater comprising a motor, a fan driven thereby, a cylindrical electrically heated wall spaced concentrically around the periphery of the tan in such manner as to constitute a fan chamber, said fan and said well being so relatively positioned that the fan blades will intercept radiant heat emanating from said wall, means for guiding a flow of cool air around the motor into the fan chamber, means for shielding the motor from radiant heat emanating from said wall, said last mentioned means being so positioned as to heat the air flow as it enters the fan chamber, and a protection enclosure for the motor fan and cylindrical wall, said enclosure having air inlet and air outlet openings.

28. An electric heater comprising a casing having a wall provided with an air inlet opening, a motor located adjacent said inlet opening and having its shaft projected therethrough, a fan mounted on said shaft, a heating chamber of annular cross section located within said casing, means for heating the wall of said heating chamher, said heated wall being located concentrically around the fan in such spaced relation that the fan will absorb radiant heat emanating from said heated wall and transmit it to the inflowing air, means associated with said air inlet opening for causing the entering air to create a cooling airflow over the motor, said casing wall, the heated wall of the heating chamber and the fan motor being so positioned with respect to each other that the casing wall protects the motor from radiant heat emanating from said heated wall and transfers said heat to the entering air stream, and a protective closure wall for said casing.

LEE P. HYNES.

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