US2129059A - Air heating and conditioning unit - Google Patents

Description

Sept. 6, 1938. G. H ERBSTER El AL AIR HEATING AND CONDITIONING UNIT 5 Sheets-Sheet 1 Filed NOV. 23, 1935 GEORGE HERBSTER JOSEPH Becvnn 1 fie-.1

ATTORNEY.

Se t. 6, 1938.. e. HERBSTER ET AL AIR HEATING AND CONDITIONING UNIT 5 Sheets-Sheet 2 Filed Nov. 23. 1935 INVENTOR5,

Grows: HsRa;7:R JOSEPH BEGVAR.

I'ORNEY.

Sept. 6, 1938. G. HERBSTER ET AL AIR HEATING AND CONDITICNING UNIT Filed NOV. 25, 1935 5 Sheets-Sheet 3 INVENTORJ.

m. "M v av E a m 55 0 HB M EH WA G 3574M w? 6J4 4 4 a P G. HERBSTER ET AL 4 2,129,059

AIR HEATING AND CONDITIONING UNIT Filed NOV. 23, 1955 5 Sheets-Sheet 4 2, NVENTOR.5

I1 '13, 5 GEORGE Hemssren JOSZSPH Bea VAR.

' ATTORNEY.

. Sept. 6, 1938. G. HERBSTER ET AL AIR HEATING AND CONDITIONING UNIT Filed Nov. '25, 1935 5 Shets-Shqet 5 M7 M. M T

INVENTORJ Gamma HERBSTER JosEP EEC VAR.

SOLO

SPEED RES/ITIING G'IJ Jul/TC ATTORNEY,

35 burners so that the temperature of the discharged the 'rtilbes- This arrangement Prevents undue 35 50 and t-Jresifictively of Fig. 1;- bustion fromv the head I. A supplem nt l, d 50 Patented Sept. 6, 1938 Y UNITED STATES PATENT OFFICE 2,129,059 AIR HEATING AND CONDITIONING UNIT George Herbster, Cleveland, and Joseph Becvar, Wickliife, Ohio, assignors to The Cleveland Cooperative Stove Company, Cleveland, Ohio Application November 23, 1935, Serial No. 51,288 3 Claims. (01.126-110) This invention relates to an air heating and p r ion nd proper correlation between the conditioning unit and particularly a unit of this various burners and fan are obtained. character suitable for installation directly in the Referring to Figs. 1 to 6 inclusive, the illusr t b h ated, trative apparatus comprises a heat exchange head One of the principal objects of the present ininto which heating med are pp y a num- 5 vention is to provide a compact, simple and .efber of gas burners, and through suitable heating flcient air heating, conditioning and humifytubes of which head air is blown by a fan. Part ing unit with cooperating means for circulating of the air, especially the slip stream from the the air through the room or rooms to be heated, fan, s p ss d through a u t hu yins 10 or supplied with conditioned air, in a manner apparatus and n mixed w h h r passe 0 such as to prevent stratification of the air in the through the tubes of the heat exchange ead. mom r r oms, For the purposes of illustration, a heat ex- Another object is to provide a unit of this char- Change d i of the yp d losed and claimed acter which is enclosed in a compact and attraci the copendihg application of ge bs e tive casing and in which the heated parts are Serial filed November 19, 1935, and 15 spaced from the casing and insulated therefrom better l rated in Figs. 1, 2 and 3 hereof, is proby two sheets of air so as to prevent substanvidsd- Thehead i comprises a upr ht boxtially any transfer of heat t t casing like structure, preferably having parallel front Another object]; to provide a, unit i whi h and rear walls to and lb respectively and being the vitiated air is continuously removed from the Sealed at the Sides- A p r li y f Ventllri tubes 20 room and utilized for purposes of combustion. 2 extend throu h he in rior of the head and Another specific object is to effect a directional p through the rear and front wells. e u es discharge of the air from the unit whereby more preferably being a d n rows in s ag ered efiective circulation of air in the room or house relationship h p t to e h other so that is obtained. heating media passing through the interior of 25 Another object is to provide a, unit of thi h the head are deflected by-each tube in a manner acter having a plurality of ga b r a of to cause the heating media to pass around and which, when operating, 1 operating at full cameinto intimate contact with the wall surface of ity and in which part only or all of t burners each tube. The tubes are so arranged that the are operable concurrently, for obtaining various Openings through the W s a a d lb are (115- 30 heating stages. posed as closely together as possible so that sub- A correlative obje t is to provide proper stantially the entire front and rear wall surfaces relation-between the rate of discharge of air by in alignment with the fan, later to be described, the fan and the amount of heat supplied by the are replacedby p nin s for admission of air to air is more nearly uniform at the different rates back pressure on e f n h n round tubes are of discharge of the air. 4 used, but if more exposed wall surface is to be Other objects and advantages will become apeliminated, the tubes y be Square e agonal parent from the following specification wherein in cross Section 50 as to fit even more Closely t 40 reference is made to the drawings in which se e e tubes 2 are tu s so that 40 Fig. 1 is a front elevation of a heating, humieven with the large entrance and discharge openfying, and air conditioning unit embodying the ings,'there is adequate space between the tubes principles of the present invention, parts thereof W th t heat e h ge head i for the pasbeing shown in section for clearness in illustrasage of heating a, nd the resistance to the tion; L flow of air due tothe contraction of the tubes 5 F1352 is a. rear elevation of the unit illustrated is negligible. 111.171 1; The head is closed at the top by a suitable Figs. 3, 4 and 5 are sectional views of the unit header 3, preferably of cast h c has 8 tak n planes indicated by th li 3. .3 4.4, passage 4 for discharge of the productsof com- Flg. 61s a top plan view of theunit, part there.- hable header 5 is provided also and forms of being shown in section for clearness in illuswith a portion of the header 4, an accumulator t tion; for receiving the products of combustion from Fig. '7 is an electrical wiring and control diathe interior of the head I and for conducting 55, gram illustrating the manner in which safetyin the same into a. flue 6 which, in turn, leads to a flue F of the room or compartment in which the unit is placed.

For supplying heating media into the interior of the head, a plurality of gas burners are utilized. The front and rear walls Ia and lb of the head I and also the side walls depend from the head below the lower row of Venturi tubes 2 to form a combustion compartment 3 which is open at the top coextensive with the interior of the head I and is partially closed at the bottom by a suitable casting 9. Depending from the ends of the casting 9 are brackets I0 for supporting the burners and gas manifold, the brackets I0 tapering from their point of juncture with the casting 3 downwardly so as to converge toward the lower ends of the burners. Suitable side walls II may be provided on the brackets I 0 and form a housing completely surrounding the lower portions of the burners.

A row of double head burners I2 are provided for supplying the heating media, these burners preferably being of the type described and claimed in the copending application of George Herbster, Ser. No. 50,575, filed Nov. 19, 1935. The burners are arranged in a row extending transversely of the heat exchange head. As more fully described in the copending application, each burner comprises a pair of twin heads I2a arranged to discharge upwardly and mounted on a common body portion I2b, the body portion, in turn, being superimposed upon a suitable flaring mixing tube I3 which terminates at its lower end in a mixing bell 14. The burners are arranged in pairs, the pairs being connected by suitable heat radiating fins I5 formed integral with and connecting the mixing tubes I3 thereof. The outer ends of each pair of burnersare provided with suitable fins I6 by which the pair of burners can be connected to each other in accurate alignment. The heads l2a of the burners are spaced apart so as to permit entrance of air therebetween and the fins I6 are so arranged that adjacent burner heads of adjacent pairs are likewise spaced apart to permit the passage of air therebetween as better illustrated in Fig. l. The burners are thus secured in a row and the end burners of the row, in turn, are secured to the brackets Ill so as to accurately position the burners. Each bracket Ill carries a depending portion Illa to which is secured a main supply gas manifold I8, the gas manifold, in turn, being provided with a plurality of gas discharge nozzles I9, one for each burner. The nozzles I3 discharge axially of the mixing tube toward the burner heads so as to prevent impingement of the discharged gas on the side walls of the associated mixing tube. A door 20 is mounted on the front wall I the compartment 8 to permit access to the burners for cleaning and lighting. The bottom row of Venturi tubes 2 is spaced a sufllcient distance above the burners to prevent impingement of the burner flame thereon. Space is provided between the side and end walls of the compartment 8 and the burners to permit access of secondary air to the burner'heads.

The head. I is preferably formed in two sections,

the upper section being of sheet aluminum and the lower section being cast iron so that-the heating of the air is'substantially the same at all portions of the head, even though the lower rows of tubes are subjected first to the heating media.

In order to blow air through the tubes 2, a motor driven propeller fan 25 is mounted in spaced rela tion to the rear of the head I. The fan 25 is driven by a suitable motor 28 which, .as better il ustrated in Figs. 2 and 3, is mounted on an upthe air'supply to the burners.

right bracket 21. The bracket is' secured to a suitable support through the medium of legs 21a which are bolted to the support by upright bolts, So that, upon removal of one bolt only, the entire bracket, with the motor and fan, can be swung around the other bolt to permit access to the fan and to the interior of the unit.

In order to prevent vibrations of the motor from reaching and causing harmonic vibrations of parts of the unit, the bracket 21 is provided, at its upper end, with yoke arms 21b with which co operate a yoke 28, the yoke arms and yoke defining an embracing support of greater diameter than the motor 25. Suitable rubber or resilient pads 29 are interposed between the motor and the yoke and yoke arms for resiliently supporting the motor.

In the plane of the fan 25 is an end wall 30 having an annular passage 30a in which the fan 25 is disposed, the wall 30 being spaced to the rear of the heat exchange head i. The wall 30, in turn, forms the rear wall of an air chamber 3| having a top wall 32 and side walls 33, this chamber 3! being uncommunicated with the interior of the heat exchange head I and the burner compartments and lower part of the main casing, later to be described so that the fan will not affect In the chamber 3| in spaced relation to the head I and to the side and front walls of the chamber 3i is a baffle wall 34, having a passage 34a permitting access to the door 20,, the wall 34 being open at the rear providing an air inlet passage 34?). Thus air from the fan is directed in surrounding relation to the combustion chamber 8 of the head I and absorbs and removes heat therefrom so as to prevent overheating of the combustion chamber. This air flows upwardly and forwardly around and in intimate contact with the head I, thus providing one air wash and then passes into the main stream from the fan.

Due to the walls 33 and 30, air from the fan is also directed around the outside of the head I and around the baffle wall 34 so as to provide a second air wash for preventing radiation of heat to the walls 33. "The flow of the first air wash stream, indicated by the arrows 38, passes around the combustion chamber 8, part passing outwardly through the passage 34a. The second air wash stream, indicated by the arrows 39, passes between the wall 34 and the wall 33, by which it is directed to the front of the head I. Thus a. double air wash is provided to prevent radiation from the head and consequent heating of the outer decorative and supporting casing.

Above the level of the combustion chamber 8, the top'wall 32 and side walls 33 terminate forwardly just in front of the wall Ia of the header, as better illustrated in Fig. 7, so that all air passing around the heat exchange head is directed along the front wall Ia of the head and consequently is intermixed with the air issuing from the tubes 2.

Enclosing all of the apparatus described is a casing 40 comprising side walls 40a spaced from the wall 33 and a rear wall 40b spaced to the rear of the fan 25. The rear wall 401) carries rearwardly extending flanges 4| which, at their rear limits, are formed to provide slideways 42 and which also define'the air inlet passage to the fan. A suitable filter screen 43 is removably fitted in the slideways 42 for filtering the air admitted to the fan, thus insuring cleaner air in the room being heated and also preventing combustible material from entering with the air and accumulating within the casing Fig. 3, a suitable spring 46 and toggle connection i and an enclosing flange 52.

being provided for normally retaining the door in upright position. The outer casing 4D is provided with a floor 48 and depending legs 50. The

rear wall of the casing extends below the level of the floor 48 and has air inlet openings 49 so that air from the room floor level may pass into that part of the casing lying belowthe casing floor 48. The legs 50 have passages 5| through which air from beneath the floor 48 may flow upwardly between the walls 33 and 40a, as indicated by the arrows 5la. The door 45, in turn, is comprised of two walls spaced apart to form an air passage therebetween, the inner wall being provided with aseries of air inlet passages a and, spaced thereabove and just below the level ot the door 20, with passages 4512. Thus air from below the floor 48 is directed upwardly, as indicated by the arrow 450, to provide an air wash between the walls of the door 45. Primary and secondary air for the burners is supplied through passages 48a formed in the floor 48.

For assuring the proper flow of air around and over the head I, deflectors 33a (see Fig. 6 are provided on the inner face of the side walls 33 of the inner casing so as to cause all air to be deflected gradually toward and along the front wall of the heat exchange head. Correspond ingly, on top of the heat exchange head are deilectors 52 which also serve the purpose of preventing concentration of heat in the corners oi the outer casing. Q

The casing is closed by a suitable top 53 which is preferably heat insulated and which swings upwardly, as indicated by the dotted line in Fig. 3, for permitting access into theinterior thereof. v p In order to provide the proper directional dis-' charge of air from the casing the front all 400 has an opening 40d which is substantial] coax-'- tensive with and in alignment with the heat exchange head I. thus carried by the front wall comprised of a plurality of directional vanes 6| The vanes 6| are sloped at an angle 01 about 15 to the horizontal -in their normal position andare of such dimensions and. spacing that the lower edge of each vane terminates above the plane of the upper edge of the next succeeding vane, thus providing projected clear spaces as indicated at X in Fig. 3. As a result there is no choking of the'flow of air or too great direct impingement thereof on the grill. The/grill is mounted in the front wall 40c for rotation about a horizontal axis extending forwardly and rea'rwardly of the head I. Thus, if it is desired to deflect" the airfrom the head downwardly. the grill 50 may be positioned as illustrated in Fig. 1. By rotating the grill about its axisrin Fig. l in a clockwise direction the air would be deflected to the left and if turned the air would .be deflected upwardly. An additional turning of 90 in the samedirectlon deflects the air to the right. Thus the air may be deflected in any direction desired for obtaining thedesired circulation, merely by rotatingthe grilljl. Ina-'15 larger-units; the grill may besupported anti-iris tlonaliy on the wall4llc, i

a front wall 400 which. at its Mounted within this opening-and 400 is a grill 50 preparatory to its discharge through the head I both for the purposes of maintaining the proper quality of air and for rendering the heating more efficient. For this purpose, there is provided near the bottom of the air inlet compartment 3|, between the head I and the wall 30, a water receptacle 10. Preferably, the receptacle carries a header II which, as better illustrated in Fig. 4, has an air inlet passage 12 at one end, the air inlet passage being controlled by a suitable damper 13. For operating the damper 13, a suitable shaft 13a. is gear connected thereto by complementary bevel gears 13?), this shaft, in turn, extending to the top of the apparatus and terminating in a suitable indicator knob 130. By turning the knob Be, the amount of air passed through the humifying receptacle can be accurately controlled. Y

At its opposite end, the "header 1| is provided with a deflectional hood '14 opening forwardly toward the head I. The passage 12 is disposed so that the fan blades are turning theretoward'. As indicated by the arrow 25a in Fig. 2, the normal tendency of the air within the air chamber 3| is to circulate downwardly toward the passage 12; alongthe top of the header 'Il toward the hood l4, and upwardly at the opposite end. As a result, a higher pressure is built up adjacent the passage 12 than adjacent the hood 14 so that the air flows through into the passage 12 through the receptacle and header I0 and 'II and out through an opening 14a beneath the" hood 14. The outer surface of the hood I4 slopes in the direction of flow of the air therepast and thus assists in creating a lower pressure zone at the opening 14a in the header H. As a result, a continuous flow of air through the receptacle and in contact with water therein is assured. In order to assist in the evaporation and absorption of water by the passing air stream. upright wicks 15 of absorbent material such as tufa rock and the like are mountedin the receptacle 10, the wicks extending from within the water in the receptacle 10 above the level thereof. In this manner a much larger water evaporating surface is provided so that the air passing through the receptacle is humifled to the proper degree. A suitable filling spout I6 is provided in the receptacle so that water may be introduced by hand if desired.

This structure makes possible circulation of a part only of the air from the fan into contact with the water and utilizes the fan ior eflecting circulation. o

In order to obtain the greatest efliciency, it is necessary that gas burnersoperate at their full rated capacity at all times while in operation. Consequently the burners H are so arranged that part of them may be burned at one time or all of them operated simultaneously. Most general field conditions are met by having one pair of the six pairs of burners adapted for constant operation and four pairs adapted for. operation only during higher heat requirements. Again, it is desirable that the rate of discharge of air by the fan be correlated to the amount of heat supplied to the head i by the burners, the fan operating at lower speed and lower delivery when only part of the burners I! are in operation and'at higher speed and higher capacity when all burners are in operation.

It has been found that once a house or coma partment has been heated to the proper tem- ;perature for comfort. much less heat is required 3 Generally, it is desirable to humidity the air slip stream of the to maintain a temperature in the comfort zone if proper circulation is maintained. Heretofore, especially with natural circulation, when a predetermined temperature has been reached, the source of heat has been entirely cut oil or materially reduced with a consequent material decrease in circulation. Thereupon the air begins to stratify very rapidly, the heated air rising along the ceiling and the colder air settling along the floor. As a result the room soon becomes uncomfortable while a few feet above the floor level the air is adequately warmed and, in fact, is too warm for comfort. With the present structure, once the proper temperature has been obtained, the heat supply is reduced materially but circulation of the smaller quantity of heated air only suflicient to replace the heat actually lost and to prevent stratification is provided. Much of the heat supposedly lost from a room is not lost but merely is located in the upper strata. With the present heater, the air is constantly drawn from the floor level, warmed appreciably and then discharged, thus afiording constant circulation free from stratification so that the air which normally lies along the ceiling and is ineffective flows or is forced down to the zone normally occupied by the occupants of the room. For accomplishing this result and rendering the structure entirely safe, the following control system is provided, and best illustrated in Fig. 5. In the bottom portion of the outer casing is a main gas inlet 88 which leads to a gas pressure regulator 8! of the diaphragm operated type from which extends the main feed line 82. The main feed line 82 is provided with a control cock 82a which is manually operated.

Beyond the cock 82a, the line 82 is connected to a thermostatic cutoff valve 83 which, in turn, is connected to a suitable Y- connection comprising branches 84 and 85, the valve 83 being operable when closed to block the fiow of gas to both branches. The branch 84 leads to the upper compartment 86a of a gas manifold which compartment supplies gas to the central pair of burners I2. The branch 85 leads around the burners to the rear of the casing to a main solenoid control valve 81 which is connected to a feed line 88 leading to the lower portion. 86b of the gas manifold. The lower portion of the gas manifold supplies only the two outermost pairs of burners, the gas supply thereto being under the cg trol of the solenoid valve 81.

Connected in the line 82 in advance of the cock 82a is a by-pass conduit 89 controlled by a suitable stop cock 89a. The conduit 89 supplies gas to the primary pilot light 98, the flow of gas thereto being controlled accurately by an adjusting needle valve 98a. Th pilot 98 is for igniting the service burners and is preferably in the form of an elongated tube having a series of jets arranged in a row lengthwise so that they terminate at the lower end adjacent a supplemental control pilot 9I. Arranged in heating relation to the pilot 9| is a bi-metal thermostatic bar 92 which is responsive to temperature changes of the pilot SI and operates the cutoff valve 83, cutting of! the supply of gas consequent upon the'supplemental pilot 8| becoming e22 ting-dished for an interval.

For supplying gas to the supplemental pilot SI, a gas conduit 93 is connected to the line 32 through the valve 83 in advance of the valve plug, so as to receive gas continuously from the line 82 when the cock 82a is open. The tube 88 extends beneath the burners and up along the sideof the outer casing interiorly thereof to the top of the apparatus wherein it is connected to a manually controlled cook 94. Leading from the cock 84 is a return line 85 which leads to the supplemental pilot 9| so that the pilot 9| can be turned on and oil by hand. Connected to the line 88 is a gas pressure operated diaphragm switch 91 having electrical contactors 91a for efiecting an electrical connection, laterto be described, consequent upon admission of gas into the vline 88 by the solenoid 81. Both in solenoid valves of this type and in pressure regulators employing a diaphragm, gas may escape past the diaphragm and into the room and to prevent this, a suitable conduit 98 is connected both to the switch 9] and pressure regulator 8I, as better illustrated in Fig. 2, and leads to a bleeder conduit 98, which leads into the exhaust stack of the apparatus.

For operating the burners in accordance with room temperatures, the solenoid valve 81 is connected by suitable conductors Hit and IM respectively to a room thermostat and to one side of a ll-vo1t A. G. circuit, a suitable wall socket lillla being mounted on the rear of the apparatus for rendering a connection of the thermostat more easy. The solenoid may be operated di rectly on a li0-volt circuit or a suitable stepdown transformer may be provided, if desired, so that the solenoid operates on lower voltage. Also leading from the same side of the 110-volt circuit as the conductor II is a, conductor Hi2 which leads to one post of a reactance control of the fan motor 25. One post of the fan is connected to the control resistance I03 through a binding post I84. The control has also a shunt binding post I85 so that the resistance may be shunted for efiecting higher speed of the fan. The binding post I is connected to a suitable conductor I 05a which leads to one contactor 81a of the switch 81 and continues by a conductor I05b to the same side ofv the l-volt line as the conductor I82, preferably by connecting conductors I02 and l05b at the resistance I83. Thus when contact is made through the switch 91, the current flows around all or part of the resistance I83 and the fan may operate at greater speed than when the current must pass through the entire resistance I03, as is the case when the switch 91 is open.

As explained it is necessary to open the valve 94 in order to operate the supplemental pilot and admit gas to any of the burners. The valve 94 also carries an electric switch having a movable blade element III), connected to the opposite side of the 110-vo1t AJC. circuit from the conductor I02 by a conductor Illla, and which, when the valve is turned to admit gas to the supplemental pilot, connects the circuit through conduits IIOa and III. As better illustrated in Fig. 7, the conductor III leads to a suitable plug fuse H2 and from this plug to the other pole of the motor 26. Thus when the valve 84 is open, the supplemental pilot operates, heating the bi-metal 92 and opening the valve 83, at the same time closing the circuit through the motor and all of the resistance I03 so that the motor runs at low speed. The room thermostat H3 is connected in the circuit by the conductor I80 and a conductor H4 and conductor Hi and when it closes, completes a circuit through the solenoid valve 81 so that the valve opens, admitting gas to the pressure operated switch 97a. At the same time it admits gas through the conduit 88 to the outer pairs of service burners. This pressure operates the switch 910. closing the circuit which shunts out a large part of the resistance Ill so that the motor operates at high speed.

The specific operation can be more fully understood by an exemplary description thereof in connection with Fig. 7. Referring to this figure and Figs. 1 and 5, the operation is as follows: the stop cock 89a is opened and the pilot 90 is lighted. Next the cock 82a is opened admitting gas to the valve 83 which is now closed. In this condition the apparatus may remain indefinitely ready for actual use. When heat is desired, the cock 94 is opened and admits gas to the supplemental pilot burner 9| which heats the the mostatic bi-metal 92 and opens the valve 83. The operation of the switch 94 for this purpose closes a circuit so that the fan operates at low speed. The openingbf thevalve Ola-also admits gas to the solenoid valve 81 at which point it is blocked. Heat is supplied only by the center pair of burners 12. when more heat is required, the thermostat Ill closes, completing a circuit through the solenoid 81 which opens and admits gas through the conduit 08 to the outer pairs of burners so that all burners are operating. At the same time, it admits gas to the valve 91. The gas pressure closes the circuit through the contactors 910, thus connecting thefan with the resistance I03 partially or fully shunted out. depending on the connection provided. As a result, concurrent increase in the speed of the fan and ignition of the outer sets of burners iseffected. After this operation is completed, the larger volume of heat is supplied until the room thermostat H3 again breaks the circuit at which times only the central burners operate and the switch 91 opens thus cutting the fan to low speed. This condition is continuous until the room thermostat again operates to demand more heat.

It might be that in some manner the fan is prevented from operation, in which case the structure would become overheated. Such heat, however, before endangering the apparatus destroys the fuse plug 2 and breaks the circuit so that the solenoid closes and only the central set of burners operate. The central burners alone are not sumcient to overheat the exchanger and other apparatuseven when the fanis not operating, so complete safety is assured.

Having thus described our invention, we claim:

1. In an air conditioning apparatus, a combustion chamber, a heat exchanger superimposed thereon and in communication therewith, a fan at the rear of and spaced from the exchanger for supplying a stream of air. a casing surrounding the chamber, exchanger and fan with its walls in spaced relation thereto, and having a discharge passage in front of the exchanger. a baille in the casing surrounding the chamber and spaced therefrom and from the casing walls and having an inlet opening admitting air from the fan, and a discharge opening remote therefrom, a baiile in the casing surrounding the exchanger and said first battle in spaced relation thereto and to the said casing for receiving air from the fan, and having a discharge passage in front of the exchanger, and means for admitting air between the second baille and walls of the casing.

2. In an air conditioning apparatus, a combastion chamber, a heat exchanger superimposed thereon and in communication therewith, a fan at the rear of and spaced from the exchanger for supplying a stream of air, a casing surrounding the chamber, exchanger and fan with its walls in spaced relation thereto, and having a discharge passage in front of theexchanger, a baiiie surrounding the chamber and spaced therefrom and from the casing walls and having an inlet opening admitting air from the fan, and a discharge opening at the front, a firing door in the combustion chamber aligned with said opening, and a second baiile in front of said discharge opening and spaced from the first battle and from the casing and having an opening aligned with the discharge opening in the first bailie, a door on said second bame for closing the opening in the second balls, and means to admit air from the fan between the said bailles whereby said air may flow from between the baiiies through the opening in the first baiiie and air' wash the firing door.

3. In an air conditioning apparatus, a combustion chamber, a heat exchanger superimposed thereon and in communication therewith, a fan at the rear of and spaced from the exchanger for supplying a stream of air, a casing surrounding the chamber, exchanger and fan with its walls in spaced relation thereto, and having a discharge passage in front of the exchanger, a baiiie surrounding the chamber and spaced therefrom and from the casing walls and having an inlet opening admitting air from the fan, and a discharge opening at the front and being open at the top for discharge of air. a firing door in the combustion chamber aligned with said discharge opening, and a second baiiie in front of said discharge opening and spaced from the first baflle and from the casing and having an opening aligned with the discharge opening of the first battle, a door on said second balls for closing the opening therein, and means to admit air from the fan between the said baffles whereby said air may flow from between the baffles through the opening in the first baile and air wash the firing door.

- GEORGE HERBSTER.

JOSEPH BEOVAR.

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