US2864359A

US2864359A - Space heater

Info

Publication number: US2864359A
Application number: US543443A
Authority: US
Inventors: Charles O Vaughn
Original assignee: SUBURBAN APPLIANCE CO
Current assignee: SUBURBAN APPLIANCE CO
Priority date: 1955-10-28
Filing date: 1955-10-28
Publication date: 1958-12-16
Anticipated expiration: 1975-12-16

Description

c. o. VAUGHN Dec. 16, 1958 SPACE HEATER "-5 Sheets-Sheet 1 Filed 001:. 28, 1955 INVENTOR CHARLES 0. VAUGHN C. O. VAUGHN Dec. 16, 1958 SPACE HEATER 3 Sheets-Sheet 2 Filed Oct. 28, 1955 INVENTOR c/mm E5 0. mus/1w www wgg Dec. 16, 1958 a Q VAUGHN 2,864,359

SPACE HEATER Filed Oct. 28, 1955 3 Sheets-Sheet 3 F166. FIG] INVENTOR CHARLES 0. VAUGHN ATTORNEY SPACE HEATER Charles 0. Vaughn, Dayton, Tenn., assignor, by mesne assignments, to Suburban Appliance Co., a corporalieu of Tennessee Application October 28, 1955, Serial No. 543,443 15 Claims. (Cl. 126-110) The present invention relates to improvements in space heaters of the internal combustion type employing a gaseous fuel and using air as the heating medium.

An important object of the present invention'is to provide a space heater symmetrical in design, whereby it can be readily installed in a'window or wall opening of the room to be heated.

A serious problem encountered with prior art space heaters of this type, when mounted in buildings at levels high above the ground, is the difiiculty in getting to the operating parts of the device for inspection and maintenance thereof without disconnecting the whole device Unite States from the building. Therefore, it is a primary aim of my invention to provide a cabinet or housing for the operating parts which will permit removal of these parts therefrom through either the front or the rear of said cabinet, for inspection and maintenance thereof.

An additional object is in the employment of a unitary air circulating means for combustion air and air to be heated whereby such means may be readily secured to and removed from a combined combustion and heat exchange assembly for cleaning purposes, repairs or replacement. "Another serious difficulty in prior art space heaters has been their lack of sufficient heating capacity to satisfactorily warm an enclosure at low outside temperatures due to dimensional limitations which the heater must not exceed. To obviate this disadvantage, my invention provides a novel type of air circulating means and an arrangement of flow paths for the combustion air and air to be heated whereby the volumetric displacement of the air being heated is greatly increased with optimum heating of such air accompanied by effective purging of the exhaust gases from the heater.

Yet another object of my invention resides in the elimination of the need for any additional venting'or flue structure except that which is contained in the heater and still achieve an effective and safe discharge of the products of combustion from the heater to the exterior of the building.

Another object of the present invention is to prevent overheating of the motor driving the air circulating means by having such motor disposed in the flow path for the outside combustion air.

In carrying out the foregoing objects, the construction of the heater embodying my invention also provides independent and separate flow paths for the outside combustion air and the circulating inside or room air to be heated.

Additional objects and advantages of the present invention will be readily apparent from the following description considered together with the accompanying drawings, in which:

Figure 1 is a perspective view showing the front of the subject heater installed in a window;

Figure .2 is a partially cut away perspective view of the heater structure showing parts of the interior combined combustion and heat exchange assembly;-

Figure 3 is a partially cut away perspective view of the combined combustion and heat exchange assembly with the burner structure removed, showing the flow paths of combustion air and room air to be heated;

Figure 4 is a fragmentary, sectional, plan view showing the air circulating means located at the rear of the combined combustion and heat exchange assembly;

Figure 5 is a fragmentary, front-elevational view with the front panel of the cabinetremoved, showing part of the heat exchange structure and the mounting means for the combined combustion and heat exchange as sembly in the cabinet;

Figure 6 is a rear-elevational view showing the open ings in the rear panel of the cabinet for the introduction and exhaust of fluids for the combustion chamber;

Figure 7 is a rear-elevational view of the heater with the rear panel of the cabinet removed; and

Figure 8 is a longitudinal cross-sectional view of'th heater taken along section lines 88 of Figure 6.

Referring now to the drawings, the present invention comprises an elongated outer cabinet, or housing 1 of generally rectangular shape in both transverse and longitudinal cross-section. The cabinet has front and rear panels 2 and 4 removably secured thereto by means of a transverse groove 3 on the front and rear of the upper wall of said cabinet and an inturned flange 5 on the top walls of panels 2, 4 adapted to be inserted insaid groove.

This structure is best seen in Figures 2 and 8. The front panel 2 is provided with a door 10 having a pair of louvers 12 therein and adapted to latch on said panel in a closed position by suitable locking means 11, as seen in Figure 8. On the side walls of the cabinet 1 adjacent the front panel, there may be provided openings 14. Openings may also be provided in the top and bottom walls of the front panel as well as the side walls. Screens may be disposed in these openings to prevent undesirable foreign matter from entering the interior of the heater. The rear panel 4 also has a louver section 16 thereon and laterally-spaced openings 18 therein. The purpose of this structure will be described hereinbelow.

The cabinet 1 is also provided with a peripheral angleiron 6 located intermediate the ends thereof and slightly forward of the longitudinal mid-point of said cabinet but rearward of the louvers 14. This angle-iron is provided with apertures 7 for suitable fasteners permitting the mounting of the heater, which will be obvious as the description proceeds.

The cabinet also comprises a pair of transverselyspaced tracks 20 secured to the inner surface of the bottom wall and running longitudinally therein (as seen in Figures 2 and 5).

Referring now to Figures 2, 3 and 5, a heating unit or combined combustion and heat exchange assembly, generally indicated at 22, is there illustrated. This assembly comprises a transverse vertical wall or partition member 26 located approximately at the mid-point of said unit and dividing the same into front and rear sec-' tions. This partition member is provided with two symmetrical openings 96. The front section of this assembly includes a combustion chamber or firebox 24 extending from the front ofthe assembly rearwardly to a point adjacent the partition member. This firebox is disposed along the longitudinal center line of the assembly. On the front wall of the firebox is provided a sight glass 28, pivotally mounted thereon and permitting observation of the interior of the firebox, in the combustion region. Laterally spaced from the side Walls of the firebox, in fluid communication therewith and parallel thereto, is a heat exchanger structure including transversely-spaced shells or

compartments

30 and 31. For purposes of either side of the .firebox, it being understood to those.-

skilled in the art that the number of such compartments may be varied, providing more or less heat transfer surface. The inner compartments 31 are connected to the firebox near the upper ends thereof by a pipe 32, whereas the outer compartments are connected to the inner compartments by means of a pipe 34 located near the lower ends thereof whereby thewaste. combustion gases flow in divided, tortuous paths from the firebox through the heat exchanger and then out suitable fines or tubes 36 extending rearwardly from the outer compartments. While only one-half of this heat exchanger structure is shown in Figure 5, it should be obvious from Figures 2 and 4 that similar structure is similarly arranged on the other side of the firebox.

It will be noted that the inner and

outer compartments

30 and 31 are also connected at their upper ends by a. pipe 40 of a considerably smaller transverse area than

thefpipes

32 and 34. The purpose of this structure will be described hereinafter.

The assembly 22 is provided at the bottom thereof with transversely-spaced, longitudinally disposed members 38 which have grooves therein adapted to be mounted onv the track means 20 of the cabinet member for permitting relative sliding movement of the heat generating unit with respect to the cabinet so that it may be withdrawn therefrom either through the front or the rear thereof when the panel members 2 or 4 have been removed, thereby facilitating maintenance and repairs of the unit.

A gaseous fuel-supplying means 42 is arranged in the firebox near the bottom thereof and comprises a pair of parallel gas burners 44. Communicating with these burners is a tubular stem 46 projecting rearwardly of the firebox through an opening therein into a space defined by a casing 48 which is disposed in the rear section of the assembly. Surrounding said tubular stem and joined to the firebox and said casing is a pipe or tube 51.

Connected with the tubular member 46-of the fuelsupply means are conventional fuel-controlling elements, such as. electromagnetically operated valve 50 and a pressure regulator 52, the former being associated with ap propriate room temperature sensing means for automatic control of the heat generated. There is also provided a conventional manual resetting means 64 extending from the front of the unit where it is accessible through door 10, to a pilot valve member 53 for igniting a pilot burner in a manner well known in the art. These last-named elements form no part of the present invention and, there fore, will not be described in detail herein. Located at the rear of the fuel-supplying means are fittings adapted to be joined to appropriate fuel connections. In this regard, suitable openings are provided in the casing 48 and thecabinet 1 for the reception of these connections. The fuel-supplying means is removably supported within the casing 48 and the firebox 24 by means of mounting

brackets

47, 49 and the tube 51. Disposed at the rear of tubular stem 46 is a flaring end portion having gen erally elliptical openings on either side thereof. These latter openings are closed by flap valves 54 pivotally connected to said tubular stem at 56'and provided with a downwardly projecting arm 58 terminating in an internallythreaded hole. Adapted to be threaded in this hole is a slender rod 60 extending tovthe front of the fuel-supplying means and terminating adjacent and coaxial with an aperture 61 formed in the front wall of the firebox. This aperture is covered by a metal plate 63,removably attached to the firebox. A suitable gasket seal isinterpo'sed between the plate and the firebox wall. A-kerf or slot 62 is cut in the forward end of the rod for manipulation thereof by an appropriate tool where,- bythe position of the flap valves may be varied.

The casing 48 has a removable rear wall 66 which; may. be connected thereto by bolts and wing nuts, as illustrated in Figure 3. The upper wall of this casing has a pair of

apertures

68, 70 thereintFigure 4) with apera ture 68 communicating with an L-shaped conduit 72, the latter terminating in an opening registering with a corresponding opening in the rear wall 66. This opening in the rear wall 66 is surrounded by a square, funnel-like element 74 having a gasket member 76 thereon and adapted to be positioned against the inner surface of the rear panel 4 of the cabinet 1 registering with the louver 16 providing a passageway for outside air into the assembly 22.

An air circulating assembly is removably attached to the upper wall of the casing 48 and to the partition member 26. This assembly comprises three

housings

78, 80 and 82 forming a unitary structure, and which may be joined together by welding, with the central housing 82 substantially hermetically sealed from the outer housings. Disposed within housing 82 is a motor 84 and a blower 86 separated from each other by a perforated plate 88. Coaxial with the motor and blower 86 are

blowers

90 and 92 located in the

housings

78 and 80, respectively. These last named housings terminate in openings at their forward ends having a circumferential mounting flange 79 for attachment to the partition member, circumscribing the openings 96 in the latter. Additionally, these last named housings comprise circular openings 94 in their outer side walls. It is to be noted that housing 82 is directly above

openings

68, 70 in the casing 48 with the plate 88 disposed intermediate these openings. The purpose of this. arrangement will be clear as the description proceeds.

The partition member 26 extends to the top wall of casing 48 and byvirtue of the alignment of the

housings

78, 80 with the openings 96, air discharged from the

blowers

90, 92 is free to enter into the front section of the assembly 22 and pass in heat transfer relationship withthe heat exchanger structure and the firebox.

It will be noted that spacer members 98 are provided between the compartments 39, 31 and the firebox 24 at the upperends thereof. These spacers not only add strength to this part of the assembly 22, but also act in connection with the forward extension of bottom wall 45 of the casing 48 to enclose the front or combustion and radiator sections of assembly 22 on all sides except the front and back. The bottom wall 45 has the longitudinally running grooved members 38 secured thereto.

The space heater of the present invention is designed to be installed either in a wall opening or in a window; When it is desired to mount the heater in a wall, the cabinet is inserted in a suitably sized opening from the inside and pushed back until the flange 6 fits snugly against the wall. The next step is to fasten the flange to the wall by screws or nails, using the holes provided in the flange. Then the joint should be made water and air-tight by means of appropriate materials, such as caulking compounds. After this is done, the heat generating unit is inserted into the cabinet and the fuel and electric connections are made and the heater is ready for operation.

Should it be desired to have the device mounted in a window, it would be necessary first to raise the window to the proper height and position the cabinet substantially equi-distant from both side jambs of the window with the mounting flange 6 disposed immediately to the rear ofjthe window sill and the bottom sash. This flange may be secured to the sash and window sill in the same manner as described for its connection to a wall opening above. Insulating filler panels 100 are arranged on both. sides of the device by fastening them to the flange and the adjoining window structure and thereby provide a substantially air-tight joint. Suitable weather-stripping may also be employed around the joints of the window to insureanair-tight connection. Once again, when the mounting of the cabinet is completed, the operating parts of thedevice-are assembled, the fuel and electric connections. are; made, and the heater is then ready for operationi Assuming that the device has --been mountedin either a wall opening or a window, as described above, its operation will now be explained. The main fuel supply valve is turned on, and with the room thermostat set to a low temperature, the pilot reset button 64 is depressed and the pilot burner is lighted by opening sight glass 28 and inserting an igniting means therethrough. After lighting the pilot burner, the room thermostat is set to the desired temperature and the device is now ready for automatic operation. When there is a call for heat, as sensed by the thermostat, the electromagnetically operated main burner valve 58 will be opened and fuel will then flow to the burners 44 where it will be ignited by the pilot flame, and simultaneously therewith, the motor 84 will be turned on and drive the

blowers

86, 90 and 92. Rotation of blower 86 results in the induction of outside air through louver 16, which air flows into conduit 72 in the casing 48 and then into housing 82 through opening 68. This air then passes through the perforations in the partition member 88 to be impelled by the blower 86 out opening 79 through the casing 48 and into the firebox 24 for combustion supporting purposes. This fiow path can best be seen inFigures 3 and 4. It should also be noted at this point, that part of the combustion supporting air will enter tubular stem 46 when valve members 54 at the rear thereof are opened and thereby effect a primary mixing of fuel and air before combustion, while. the fuel is flowing to the burners. As these valve mem: bers are adjustable, the amount of the combustion air. used for primary mixing with the fuel can be regulated. Such adjustment can be accomplished by removing the front panel of the cabinet detaching plate 63 and inserting a screw driver in the kerf 62 of rod 60, turning the same in the desired direction. The remaining portion of the combustion air which does not enter tubular stem 46, passes under pressure through tube 51 into the combustion region surrounding the burners 44, providing a further mixing of the fuel mixture with air, resulting in optimum combustion characteristics. Because of the pressure of such air, it will also operate to purge the burning gases out of the firebox, through the heat exchanger structure and out flues 36 and openings 18 in the rear of the cabinet member to be discharged to the atmosphere at a safe distance'from the building wall. Baffie members 102 are provided over each opening 18 to prevent heavy gusts of wind from entering flues 36 and thereby disturb the flow pattern of the combustion system and perhaps cause the flame to be extinguished.

During the operation of the burner, the exhaust gases flow in tortuous paths from the firebox through

pipes

32, 34 and compartments 3t), 31, thereby heating the same. Since the two

compartments

30, 31 are also connected at their upper ends by pipe 40, combustion gases will pass directly from the firebox into the outermost compartanent, thereby tending to maintain the temperature of the latter substantially the same as that of the inner compartments 3% for more effective heating of the air that contacts these outer compartments.

While combustion is taking place and blower 86 is operating to provide proper combustion air,

blowers

90 and 92 are also operating to circulate the room air for heating purposes. This is accomplished in the following manner: Room air is drawn into the heater through louvers or openings 14 in the side walls of the cabinet member and flows rearwardly toward said blowers, during which time it is preheated by passing in heat exchange relationship with the outer surface of each outermost compartment 38. Such air then enters into each blower housing 78, 8t throughv the opening 94 therein to be impelled in a forward direction through the apertures 96 in partition member 26, whereby the air is further heated as it passes between and in contact with the firebox and heat exchanger structure.

through the louvers 12 in the front panel'Z.

As this air leaves the heat exchanger structure, it discharges back into the room It is obvious that the flow of outside combustion air will be in'dependentof the flow path of the circulating room 'air due to the construction of the blower housings and thereby objectionable quantities of the cold outside air will be prevented from entering the space to be heated.

It should be noted that with the arrangement of dual blowers for the circulating room air, the heating capacity of such a compact unit, as here described, is greatlyincreased since air is drawn in from both sides of the device, and, furthermore, flow paths for such air whereby it is preheated as it flows rearwardly towards the blower inlets, result in optimum heating of such air and a great saving in fuel costs.

By means of the removable front and rear panels for the cabinet member, access may readily be had to either the front or rear of assembly 22 for inspection and maintenance thereof. In this connection, when either the front or rear panel is removed and the fuel and electric connections are disengaged, the entire assembly 22 may be withdrawn from the cabinet by means of the track and

groove structure

20, 38, permitting sliding movement of the assembly 22 in either a forward or rearward direc{ tion. With this arrangement, those operating parts, such as are located in the rear of the assembly 22, may be readily inspected, replaced or repaired, irrespective of the level above the ground that the device is mounted, without having to resort to a dismounting of the entire. device from the window or wall structure. The unitary air circulating assembly is mounted on the casing 48 and partition member 26 by bolts or similar fasteners so that it may be readily removed from such structure for cleaning purposes or replacement by a similar assembly. It is to be noted that the motor 84 is positioned in the outside combustion air flow path so that such air, when flowing to the firebox, will pass over said motor, tending to cool the same and prevent over-heating thereof.

It is obvious, as was mentioned hereinbefore, that the number and disposition of the openings in the cabinet for the circulating room air can be varied and this will not disturb the general flow pattern involved in the illus-, trated embodiment of my invention. With openings in the top and bottom wall of the cabinet air would also' be drawn in a rearward direction over the spacer members 98 in the top of the firebox and also under the bottom of casing member 48 to the blower housings 78 and 80where it would mix with the air drawn in through the side openings. I

It should be apparent to those skilled in the art that the blower 86 for outside combustion air may be elim-f inated and the heater would still operate to draw in outside air due to the natural draft set up by the combus-fl While specific structures have been shown and de scribed, it is to be understood that departures may be made therefrom within the spirit of my invention. Therefore, it is my intention that the present invention should not be limited to such specific structures but be measured' by the scope of the accompanying claims.

What is claimed is:

1. In a fuel burning heater, a heating unit comprising a forward section, an intermediate vertical wall having ap ertures therein, and a rear section; said forward section comprising a centrally disposed firebox of parallelepiped configuration having fuel-burning means therein, means for supplying fuel to said fuel-burning means, and later. ally spaced compartments communicatively connected to. said firebox on either side thereof and providing divided,'

tortuous paths for the products of combustion leaving the firebox; said rear section comprising a casing communicating with said firebox and having a top wall and rear wall, said top wall being provided with transversely-,

spaced openings therein and said rear wall also being provided with an opening therein, a conduit connecting said latter opening with one of said transversely-spaced openings in the top wall, and a first housing having an open bottom arranged on the top wall of said casing and enclosing the openings therein, a pair of laterally-spaced housings secured to said first housing on opposite sides thereof and having inlet and outlet means therein, said latter housings being removably secured to said intermediate Wall with their outlet means encircling said apertures in the latter; a prime mover arranged in said first housing and each of said housings having a blower therein coaxially connected with said prime mover, and said first housing further comprising a perforated plate intermediate the spaced openings in the top wall of said casing and. dividing said latter housing into communicating chambers.

2. In a room heater of the internal combustion type, a generally rectangular, tubular cabinet being opened at the front and rear ends thereof, an external flange on said cabinet, intermediate the ends thereof, for mounting said cabinet in a window or wall opening, transverselyspaced tracks extending longitudinally in said cabinet on the bottom wall thereof, a heating unit arranged in said cabinet, said unit including guide means engaging said tracks to slidably support said unit in said cabinet, front and rear panels removably connected to said cabinet, said cabinet having circulating room air inlet openings formed adjacent the front thereof, said front panel having circulating room air outlet openings formed therein, and said rear panel having combustion air inlet and exhaust gas outlet openings therein, said heating unit further including a combustion chamber communicating with said combustion air inlet opening and a heat exchanger communicatively connected to said combustion chamber to receive the products of combustion therefrom, and means forming intercommunicating circulating room-air passageways for the conduction of air in heat exchange relation with said combustion chamber and said heat exchanger and cooperating with said room air inlet and outlet openings, duct means for said heat exchanger communicating with said exhaust gas outlet opening, and air blower means arranged to draw air, in through said room-air inlet openings, to pass it through said air passageways and to discharge it through said room-air outlet openings.

3. In a room heater of the internal combustion type, means forming a cabinet structure having a front wall and a rear wall, combustion air inlet and exhaust gas outlet openings arranged in the rear of the cabinet structure, circulating room air inlet and outlet openings arranged in the front of the cabinet, a heating unit mounted in said cabinet, said heating unit comprising a partition dividing said unit into two sections, one of said sections being disposed adjacent said circulating room air openings and including a combustion chamber and a heat exchanger communicatively connected to said combustion chamber to receive the products of combustion therefrom and defining circulating room-air passageways therethrough. means in said one section cooperating with said cabinet to define a circulating room air passageway surrounding said one section, and the other section of said heating unit including a casing disposed subjacent said partition and in fluid communication with said combustion chamber, duct means extending from said heat exchanger to said exhaust gas outlet openings, a blower assembly in said other section comprising a plurality of laterally-spaced coaxial blowers, a housing for each blower, one of said housings being centrally disposed with respect to the other housings and being removably connected to said casing and means establishing COl'IllTlll',

nication between said combustion air inlet opening and said casing, the other housings being connected to said one housing and also being removably connected. to said partition, the latter housings each having inlet means communicating with said surrounding circulating roomair passageway and also having outlet means communicating with said circulating room-air passageways in said heat exchanger through openings in said partition, the latter passageways communicating with the cabinet circulating room-air outlet openings.

4. The structure defined in claim 3 wherein fuel burner means is arranged in the combustion chamber and extends into the casing, and means in said casing for controlling the flow of fuel to said burner means.

5. The structure defined in claim 3 wherein the blowers are arranged in coaxial relationship, a prime mover for said blowers mounted in one of the housings, and means for pneumatically isolating the centrally disposed housing from the other housings.

6. in a fuel burning heater, a heating unit adapted for mounting in a room wall opening, said unit including a combustion chamber having a front wall portion, a fuel burner in said combustion chamber, said burner having a tubular stem extending rearwardly of said front wall portion, means for supplying fuel to said stem, said stem terminating in a plurality of openings for the admission of air into said stem for primary mixing with fuel within said stem, valve means for closing said openings, adjusting means operatively connected to said valve means for regulating the position thereof, said adjusting means extending from said valve means into said combustion chamber to a position adjacent said front wall portion, and said front wall portion being provided with an opening for access to said adjusting means.

7. A fuel-burning heater unit comprising a forward section, a rear section and an intermediate vertical wall separating said sections, a combustion chamber in the forward section, a laterally-spaced compartment in said forward section and communicatively connected to said combustion chamber and defining therewith a passageway for air to be heated, a flue extending from said compartment for the discharge of the gases of combustion passing from said combustion chamber to said compartment, fuel-burning means in said combustion chamber, means for supplying fuel to said fuel-burning means, a casing in said rear section having a top wall with an opening therein, a housing mounted on the top wall of said casing over the opening therein, means whereby air may be introduced into said housing, an air pump in said housing, said air pump discharging air through said opening, and conduit means extending from said opening to said fuel-burning means for the conduction of combustion air from said air pump to said fuel-burning means.

8. A fuel-burning heater unit comprising a forward section, a rear section and an intermediate vertical wall separating said sections, a combustion chamber in said front section, a compartment at each side of said combustion chamber in said front section, said compartments being spaced from said combustion chamber, communicatively connected thereto and defining with said combustion chamber passageways for air to be heated, a flue extending from each compartment for the discharge of gases of combustion passing from said combustion chamber to said compartments, fuel-burning means in said combustion chamber, means for supplying fuel to said fuel-burning means, a casing in the rear section having a top wall with two openings therein, a housing mounted on said top wall over the openings therein, conduit means extending from one of the openings in the top wall to the combustion chamber, a conduit connected to the other of said openings in the top wall for the supply of air therethrough to said housing, and an air pump in said housing, said air pump forcing air introduced into said housing through said last named opening and through said first-named opening and said conduit means to said combustion chamber.

9. A fuel-burning heater unit as set forth in claim 8 in which the casing in the rear section has a rear wall having an opening, the housing is removably mounted on said casing and the opening in the rear wall is connec.ed through said conduit to the opening in the top wall of the casing through which air is supplied to said housing.

10. A fuel-burning heater unit as set forth in claim 9 in which the housing is provided with laterally-spaced, vertical walls dividing said housing into an intermediate housing overlying the openings in the top wall of said casing and an end housing at each side thereof, an air blower in each of said end housings, and means for condacting air from said air blowers into said front section to pass over the compartments connected to the combustion chamber.

11. A fuel-burning heater unit as set forth in claim 10 in which said intermediate housingis pneumatically isolated from said end housings, said air pump and a motor are located in said intermediate housing and said air pump and said blowers are co-axially aligned and each are driven by said motor.

12. A space heater adapted for mounting in an opening in a wall comprising a cabinet having top, bottom and side walls and being open at each end, transverselyspaced, longitudinally-extending tracks of inverted V-shape in cross section located on the inside of the bottom wall, a heating unit within said cabinet, said heating unit having transversely-spaced guide means mounted on said tracks, said guide means being complementary to and fitting over said inverted V-shaped tracks, whereby said heating unit may he slid along said tracks and removed through an open end of said casing, said heating unit including a heater, a heat exchanger communicatively connected to said heater, and blower means for blowing air over said heat exchanger and out of said casing through openings therein.

13. A space heater adapted for mounting in an opening in a wall comprising a cabinet having top, bottom, side, front end and rear end walls, the front end wall anzl the adjoining front portion of the cabinet being adapted to extend into a space behind said wall, a heating unit in said cabinet, said heating unit comprising a heater in a forward portion of said cabinet, a heat exchanger compartment communicatively connected to said heater at one side thereof, said heat exchanger compartment, being spaced both from the heater and the adjacent side wall of the cabinet and forming a Wall portion of a passageway for air to be heated between said heat exchanger compartment and the heater and also defining a wall portion of a further passageway between said heat exchanger compartment and the adjacent side wall of the cabinet,

and blower means in a rearward portion of said cabinet, the intake of said blower means being in communication with the passageway for air to be heated between the heat exchanger compartment and the adjacent side wall of the cabinet, conduit means extending from the discharge of said blower means to the passageway for air to be heated between said heater and said heat exchanger compartment, the cabinet having an opening in the front portion thereof positioned to admit air from outside the cabinet into the passageway between the heat exchanger compartment and the adjacent side wall of the cabinet, said .abinet also having an opening in the front wall, whereby said blower means will draw air in through said opening in the front portion of the cabinet and over the outer wall of the heat exchanger compartment and discharge it through the passageway defined by the heater and the inside wall of the heat exchanger compartment and out through the opening in the front wall of the cabinet.

14. A space heater as set forth in claim 13 in which a heat exchanger is positioned in a like manner at each side of the heater and the cabinet has openings in each of is side walls, near the front, for the passage of air from outside the cabinet into the passageways between the heat exchanger compartments and the side walls of the cabinet.

15. A space heater as set forth in claim 14 in which there are two blowers, one for drawing air in through each of the openings in the side walls of the cabinet and over the outer wall of the heat exchanger compartment adjacent thereto and discharging it through the passageway defined by the heater and said adjacent heat exchanger compartment and out through the front wall of the cabinet.

References Cited in the file of this patent UNITED STATES PATENTS 8,104 Pierce May 20, 1851 2,178,703 Robbins Nov. 7, 1939 2,249,285 Degler et al. July 15, 1941 2,386,115 Holthouse Oct. 2, 1945 2,482,552 Korsgren Sept. 20, 1949 2,496,505 Thompson Feb. 7, 1950 2,508,131 Zink May 16, 1950 2,561,100 Dahlstrom July 17, 1951 2,581,942 Collins et al. Jan. 8, 1952 2,685,875 Eichhorn Aug. 10, 1954 2,720,876 Salners et a1. Oct. 18, 1955