US3797474A

US3797474A - Fuel fired space heater

Info

Publication number: US3797474A
Application number: US00361519A
Authority: US
Inventors: J Eichenlaub
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-05-18
Filing date: 1973-05-18
Publication date: 1974-03-19
Anticipated expiration: 1991-03-19
Also published as: DE2410171A1; FR2229928A1; FR2229928B3; IT1010007B; JPS5027144A

Abstract

A fuel fired space heater directing infrared in a downward direction from a radiant confined within a combustion chamber at the lower end of an elongate inclined housing, an enlarged combustion gases discharging chamber above said combustion chamber and delivering the combustion gases to an outlet, the housing having a radiant heat discharging port beneath said combustion chamber, and a flexible panel of a material highly transmissive of infrared and also being inclined with the lower edge of the inclined panel secured to the housing adjacent the radiant heat discharging port and the upper side portion of the panel being spaced from the housing or supplied by an air intake passageway, but confronting the entire port to enclose the port and deliver combustion air downwardly along the inner face of the panel for preventing deposit of dust and delivering cool combustion air for cooling the panel and supplying air to the fuel fired radiant. Space heaters for extremely dusty spaces such as turkey houses where a substantial amount of litter is on the floor usually require an extreme amount of maintenance so as to remain functional, primarily because of the dust that must be contended with in such installations. In turkey brooders, a substantial amount of the dust is airborne of which 20 percent by weight is in continuous suspension and 80 percent is sedimentary so as to settle on everything that has a somewhat horizontal surface. Insurance and other applicable codes vary from place to place and the nature of the fuel fired heating installation will be controlled accordingly. It has been a problem to accommodate the installation codes of heaters as well as to accommodate the dust problem which is always present and which is of primary importance in the design or selection of a heater for a particular installation.

Description

United States Patent [191 Eichenlaub Mar. 119, 1974 FUEL FIRED SPACE HEATER John E. Eichenlaub, 9321 Franklin Ave, West, Minneapolis, Minn. 55426 [22] Filed: May 18, 1973 [21] App]. No.: 361,519

[76] Inventor:

Primary Examiner-William E. Wayner Assistant ExaminerWilliam E. Tapolcai, Jr. Attorney, Agent, or Firm-H. Dale Palmatier; James R. Haller [57] ABSTRACT A fuel fired space heater directing infrared in a downward direction from a radiant confined within a combustion chamber at the lower end of an elongate inclined housing, an enlarged combustion gases discharging chamber above said combustion chamber and delivering the combustion gases to an outlet, the

housing having a radiant heat discharging port beneath said combustion chamber, and a flexible panel of a material highly transmissive of infrared and also being inclined with the lower edge of the inclined panel secured to the housing adjacent the radiant heat discharging port and the upper side portion of the panel being spaced from the housing or supplied by an air intake passageway, but confronting the entire port to enclose the port and deliver combustion air downwardly along the inner face of the panel for preventing deposit of dust and delivering cool combustion air for cooling the panel and supplying air to the fuel fired radiant.

Space theaters for extremely dusty spaces such as turkey houses where a substantial. amount of litter is on the floor usually require an extreme amount of maintenance so as to remain functional, primarily because of the dust that must be contended with in such installations. In turkey brooders, a substantial amount of the dust is airborne of which 20 percent by weight is in continuous suspension and 80 percent is sedimentary so as to settle on everything that has a somewhat horizontal surface.

Insurance and other applicable codes vary from place to place and the nature of the fuel fired heating installation will be controlled accordingly. It has been a problem to accommodate the installation codes of heaters as well as to accommodate the dust problem which is always present and which is of primary importance in the design or selection of a heater for a particular installation.

14 Claims, 11 Drawing Figures PMENTED m 1 9 $974 SHEET 1 BF 3 FIEZE 3L797L4T4 PATENTEDHAR 1 9 1914 SHEEI 2 OF 3 PATENTEDHARIS m4 3797L474 SHEET 3 BF 3 FUEL FIRED SPACE HEATER SUMMARY OF THE INVENTION A gas fired space heater with the flame heated radiant and combustion chamber almost entirely enclosed except for the combustion air inlet. A principal heat discharge is a radiant heat transmissive panel through which infrared from the radiant is radiated. The panel is generally horizontal and disposed beneath the radiant to transmit infrared downwardly, but the panel is slightly inclined whereby cool combustion air admitted into the combustion chamber at the upper edge of the panel will rapidly sweep along the panel and downwardly to cool and continuously clean the panel of dust.

The radiant heat transmission panel may be concavely curved from side to side relative to the substantially flat radiant so that the portion of the panel confronting the center of the radiant, where the infrared is most intense, is spaced farthest from the radiant.

The heater also incorporates a heat exchanger section with a combustion gases-carrying plenum chamber superiorily disposed relative to the combustion cham-' ber and in open communication therewith. Because of the arrangement of the plenum chamber relative to the combustion chamber, combustion gases do not move back into the combustion chamber.

The heater may be completely sealed against gaseous communication with the space being heated by exhausting from the heat exchanger to an exterior space and by also supplying air to the upper edge of the heat transmissive panel from the same exterior space which may be at the outside of the building.

Combustion air may be supplied to the heater by a duct incorporating the heat transmissive panel as a portion of the duct. Such a duct may supply combustion air from the exterior of the space being heated. In certain instances it may be desirable to exhaust the combustion gases directly into the space being heated, whereupon the space must be maintained under negative or neutral pressure, relative to the pressure within the combustion chamber so as to continuously exhaust the gases from the combustion chamber and to exhaust the atmosphere from the space being heated and as to draw fresh combustion air through such a supply duct from the exterior of the space being heated.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 isan elevation view of a space heater mounted on a ceiling in an overhead position according to the present invention.

FIG. 2 is a somewhat enlarged longitudinal section view of the heater of FIG. 1.

FIG. 3 is an enlarged transverse section taken approximately at 3-3 in FIG. 2.

FIG. 3a is a detailed transverse section view of a modified form of the invention and taken on a plane as indicated at 3a-3a in FIG. 3b.

FIG. 3b is a detailed longitudinal section view of the form of heater illustrated in FIG. 3a and taken on a plane substantially as indicated at 3b-3b in FIG. 3a.

FIG. 4 is a longitudinal section view of a modified form of space heater.

DETAILED DESCRIPTION OF THE INVENTION One form of the invention is illustrated in FIGS. 1 3 and comprises an elongate housing 10 having a cylindrical sidewall Ill and closed ends .12 and 13. The elongate housing 10 is maintained in an inclined position, and the inclination may be as much as 45 fromhorizontal. The upper end wall 13 of the housing has a combustion gases discharging outlet 113.1 formed therein, and a stack I4 may be secured as by welding to the housing so as to receive and carry away all the combustion gases from the outlet 13.1. A mounting bracket 15 is affixed to the housing 10 as by welding in order to facilitate mounting of the housing at the desired location and position so as to direct heat to the desired area.

The housing It) defines an enlarged substantially unobstructed interior plenum 16 which defines a combustion chamber I7 adjacent the lower end of the housing,

I and a combustion gases discharging chamber 18 adja- FIG. 5 is a detail elevation view with portions thereof broken away for clarity of detail and illustrating another modified form of the invention.

cent the upper end of the housing. The combustion gases discharging chamber is in unobstructed gas flow communication with the combustion chamber 17 and is always maintained at a superior elevation relative to the combustion chamber 17. A radiant 19 of ceramic or similar material has a plurality of apertures therethrough for delivering a gas and air mixture suitable for producing a small flame at each of the apertures and a multiplicity of the small flames across the whole flat infrared radiating face of the radiant 19. The radiant I9 is mounted on a suitable gas and air mixing housing 20 which receives the combustion air at the ports 21 and gas from the valve and pipeline 22. The gas burner housing 20 is mounted on the lower end wall 12 of the housing 10 and is inclined as to position so that the combustion air is delivered to the port 21 at the lower end of the housing and there is no possibility that the products of combustion or combustion gases from the flames will be recirculated into the ports 21. All of the products of combustion fromthe face of the radiant and the flames thereon will move upwardly toward the top of the housing and into the combustion products delivery and discharging chamber 18 toward the outlet 13.].

The housing 10 has an enlarged infrared and radiant heat discharging port 23 adjacent the combustion chamber 17 and extending substantially one-third to one-half around the lower periphery of the cylindrical sidewall 11 beneath the radiant 19. The port 23 has a length slightly greater than the length of the radiant l9 and the width of the port 23 between the longitudinally extending side edges 23.1 is substantially equal to the diameter of the cylindrical sidewall 11 and significantly wider than the width of the radiant 19. It should be clear that the width of the infrared. discharging port 23 as measured around the transverse periphery of the cylindrical sidewall is very significantly wider than the radiant 19 because the longitudinally extending side edges 23.1 are both closely spaced to a diametric plane extending along the axis of cylindrical sidewall 11.

The upper end edge 23.2 of the infrared discharging port 23 is maintained at a superior elevation above the lower end edge 23.3 of the port by virtue of the inclined orientation of the housing 10.

The infrared and radiant heat discharging port 23 is substantially closed by a thin and flexible panel 24 of a material which is highly transmissive of infrared and radiant heat. The panel 24 may be constructed of a film type material known principally by its trademark TEF- LON, which is transmissive of approximately 88 percent of infrared directed thereto, or a polyester resin film material known principally by its trademark MYLAR which is capable of transmitting approximately 77 percent of the infrared radiation applied thereto. It is important that the panel 24 be highly transmissive of infrared so that an excessive amount of heat is not accumulated in the panel as the infrared is transmitted therethrough. The known rigid forms of glass and variations thereof, one of which is known by its trademark VICOR, are unsatisfactory to serve to close the infrared discharging port 23 and are not suitable for this invention because such material absorbs significantly too much heat. Such rigid glass-like material cannot be cooled so as to be safe to be touched while the thin flexible film type panels 24 of the materials described are safe to touch and are capable of withstanding temperatures produced with the cooling provided.

. The film-like panel 24 is secured to the exterior of the cylindrical sidewall 11 by a spring clip 25 which is secured in the edge of the panel 24 and which is sufficiently long as to extend around more than half the periphery of cylindrical wall 11, and the resilience of the rod-type bracket 25 is sufficient to grip the wall 1 1 and securely anchor the panel 24 adjacent the lower end edge 23.3 of the periphery of port 23. The panel 24 extends somewhat more than halfway around the periphery of cylindrical sidewall 11, and as seen in FIGS. 1 and 3, the longitudinally extending side edges 24.1 of panel 24 extend longitudinally along the cylindrical sidewall 11 in spaced relation with the side edges 23.1 of the port 23. The side edges 24.1 of the flexible panel 24 actually will lie flush against the exterior surface of the cylindrical sidewall 11 so as to produce a substantially sealing relation with the housing sidewall.

The panel 24 is held away from the cylindrical sidewall 11 and away from the upper end edge 23.2 of the port 23, and substantially all portions of the panel 24 except at the longitudinally extending side edges 24.1 and at the anchoring bracket 25. The panel 24 is maintained in an inclined position, substantially as illustrated in FIGS. 1 and 2 by a plurality of elastic anchor cords or metal springs 26 which are secured to the panel 24 at grommets 24.2, and the cords 26 are secured to a mounting bracket 27 affixed as by welding to the housing sidewall 11. In the form shown, the ends of the mounting bracket or rod 27 are welded to the housing sidewall, and intermediate supporting brackets and braces may be provided for rod 27 as required.

The upper side or edge portion 24.3 of the flexible panel 24 is maintained in spaced relation with the adjoining portions 11.1 of the housing sidewall so as to cooperate therewith in defining an air passage 28 for directing combustion air into the combustion chamber to provide primary and secondary air for the fuel fired flame at the radiant. Because the air flowing through passage 28 as indicated by the arrows a is relatively cool compared to temperatures existing in the plenum l6 and more specifically the combustion chamber 17, the air remains closely adjacent and sweeps along the panel 24 so as to continuously cool the interior surface of the panel 24, thereby cooling the entire panel 24. The passage 28 is sufficiently long and broad as to be assured that the air flow therethrough is relatively smooth and without any significant turbulence so that the air will smoothly flow into the combustion chamber and toward the port 21 and the face of the radiant 19. The panel 24 is stretched taut to be free of wrinkles and to avoid causing turbulence of the flowing air.

It will be recognized that the panel 24 confronts the entire infrared and radiant heat discharging port 23, and that the panel 24 has a generally rounded and slightly conical shape throughout the whole portion of panel 24 which confronts the port 23. On the other hand, the radiant 19 is substantially planar in shape so that the flat front face of the radiant from which the infrared radiates confronts varying areas of the panel 24 in varying angles of confrontation. The areas of the panel 24 which are directly beneath the radiant 19, and lie generally parallel to the flat radiating face of the radiant 19 are spaced a maximum distance from the radiant 19 so as to avoid excessive heating; the portions of panel 24 in the vicinity of the longitudinal side edge 32.1 of the port are in the closest proximity with the radiant 19, but the angle of confrontation of these portions of the panel 24 with the flat radiating space of the radiant 19 is very substantial and therefore a rather minimum proportion of the radiant energy is directed to the nearest areas of the panel 24.

It has been found that the combustion air moving in the direction of arrows a sweep the flexible panel 24 of most of the dust and maintain the panel quite clear, regardless of the dust content of the air. Essentially no significant quantity of dust is allowed to settle on the panel 24 because of the continuous sweep of air thereacross.

In some situations it may be desirable to allow the heater 10 to operate by gravity due to the temperature of the air in the plenum 16 and the construction of the heater 10 which will cause the air and products of combustion to flow as indicated. Combustion gases may be discharged through a flue to the exterior of the space being heated. It may be desirable in certain instances to connect the outlet duct or flue 14 to a suction fan so as to produce forced flow of air and combustion products through the heater. As the hot combustion gases flow through the discharging chamber 18, the heat conductive sidewall 11 will conduct away a portion of the hear from the gases for additional heating of the space.

Combustion gases may bedischarged into the space being heated if the space is well ventilated as by fans. Combustion air may be also drawn from the space being heated.

However, it should be understood that the principal heating produced by the heater 10 is by infrared passing through the panel 24 from radiant 19.

It may be desirable to mount a heater adjacent an outside building wall W as illustrated in FIG. 4 so that the heater 10' will draw the combustion air from the exterior E of the wall and so as to discharge the combustion gases from the housing to a location at the exterior of the wall. In this form of the invention, the heater has an interior plenum 16' defining a combustion chamber 17 and a combustion gases discharging chamber 18' which is disposed at a superior elevation relative to the combustion chamber 17 and relative to the radiant 19'. In this form of the invention the combustion gases discharging flue duct 14' may be extended horizontally through the wall W. The flexible TEFLON or MYLAR infrared transmissive panel 24' is laid against the exterior of the housing sidewall 11' around the entire periphery of the infrared discharging port 23'. The combustion air is brought through a duct which extends through the wall W and draws air from the exterior E. The duct 30 incorporates an air flow smoothing plenum chamber 31 which discharges directly into the plenum 16' adjacent the upper edge of the flexible panel 24' so as to cause the incoming combustion air to flow through the inlet 32 and cool the panel 24' as previously described. This heater 10' is completely sealed as relates to the spaces at the interior side of wall W which are to be heated so as to minimize the entrance of dust into the heater and to minimize the exposure of the flame to the atmosphere within the space.

In the form of heater illustrated in FIGS. 5, 6 and 7, the heater 10.1 has a construction substantially identical to that illustrated in FIGS. 1 3. In this form of the invention, the flexible panel 24a is arranged in relation to the infrared and radiant heat discharging port 23a in the same fashion as described in connection with FIGS. 1 3. In addition, the panel 24 is formed integrally of and merges into a duct 24a of the same TEF- LON material which is clamped or connected at 35 to an air supply duct 36 which may be formed of any suitable material such as rigid metal or polyethylene, or any other suitable duct-type material. The TEFLON duct 24a is laid against the lower side of the housing sidewall and has an edge 24b secured to the heater housing sidewall adjacent the upper end edge of the infrared discharging port 23a so as to entirely seal the TEFLON duct 24a to the heater housing 10.1.

This form of heater illustrated in FIGS. 5 7 may be connected to a conventional flue or discharge duct, or this heater may discharge combustion gases directly into the space being heated in which case the space must be operated under negative pressure under influence of a fan which continuously draws air and combustion gases out of the space being heated. The combustion air may be supplied from the duct 36 from a location outside the space being heated, such as the exterior of the building. In the form of the invention illustrated in FIGS. 8 and 9, the heater 10.2 is essentially identical to identical to that illustrated in FIGS. 1 3. However, in this form of the invention, an air baffle 37 is mounted within the housing at a location adjacent the end edge of the infrared discharging port 23 so as to prevent combustion gases from flowing downwardly along the infrared transmissive panel 24 and commingling with these combustion gases for recirculation to the flame heated radiant 19.

In the form of invention illustrated in FIGS. 3a and 4a, the heater 10.3 is substantially the same as illustrated in FIGS. 1 3 with the exception that the housing 11.3 has a substantially square or rectangular transverse shape. The thin flexible panel 24.3 is stretched taut across the open bottom of the housing which defines the infrared discharging port 23.3; and the Teflon flexible panel 24.3 is drawn tightly across the rounded lower edges of the sidewalls 11.30: of the housing, and the Teflon panel 24.3 is secured by a suitable bracket or anchor to one sidewall of the housing and is held secure at the other side of the housing by an elastic cord or spring 33.3 which is detachably secured to an anchor element such as hook 34.3 on the side of the housing. The housing 10.3 has an air supply duct and plenum 35.3 formed integrally thereof or affixedly secured thereto as illustrated in FIG. 3b. Combustion air is delivered through the duct and plenum 35.3 to the upper side edge of the Teflon panel 24.3 so that the air flows smoothly across the Teflon panel] and then upwardly into the combustion chamber 17.3. It will be seen that the Teflon panel 24.3 is also stretched in a longitudinal direction of the heater 10.3 by an elastic cord or spring.

26.3 which is secured as by grommets to one end edge of the Teflon panel 24.3 and is detachably secured to an anchor 26.3a on the end wall of the housing. This form illustrated in FIGS. 30 and 3 b is particularly well adapted to bringing air into the heater 10.3 from an exterior location, because the rectangular or square transverse configuration lends itself to easy attachment of the combustion air delivery duct and plenum 35.3.

The air delivery passage 28.3 defined between the upper side edge portion of the Teflon panel 24.3 and the bottom wall 11.3b of the housing extends entirely across the width of the housing withoutinterruption or interference so that there is essentially no influence which would tend to cause turbulence in the flow of air sweeping downwardly across the taut panel 24.3 for cooling of the panel and supplying combustion air to the radiant.

It will be seen that I have provided a new and improved fuel fired space heater directing infrared in a downward direction from a radiant confined within a combustion chamber adjacent the lower end of an elongate and inclined housing and downwardly through a flexible panel of material highly transmissive of infrared wherein the panel is drawn taut across a large radiant heat and infrared discharging portin the lower side of the housing. An air inlet is provided adjacent the upper edge of the inclined flexible panel to provide combustion air for the fuel fired radiant and to continu ously cool the flexible panel of infrared transmissive material as the inwardly flowing combustion air flows smoothly downwardly across the panel.

What I claim is:

1. A fuel fired space heater, comprising:

a flame heated radiant facing generally downwardly and directing infrared downwardly for heating such a space;

an elongate enclosed housing defining a plenum chamber having a combustion portion encompassing said radiant and also having a combustion gases discharging portion adjacent to and at a superior elevation relative to said combustion portion, said discharging portion being in open and direct gas flow communication withthe combustion portion of the plenum chamber, and the housing having a combustion gases discharging outlet communicating with the gases discharging portion of the plenum chamber and said outlet also being at a superior elevation relative to the combustion portion of the plenum chamber, the housing also having downwardly facing radiant heat discharging port disposed below said radiant and below the combustion portion of the plenum chamber, there being one lower side of the periphery of the port disposed at a lower elevation than the opposite upper side of the periphery of the port;

a thin flexible inclined panel of material highly transmissive of infrared and confronting and obstructing the entire radiant heat discharging port, the side portions of the panel being in close fitting and substantially sealing relation with the sides of the periphery of the radiant heat discharging port, the upper end of the inclined panel being in spaced and confronting relation with and beneath the housing adjacent the upper side of the periphery of the radiant heat discharging port and cooperating with the housing to define a combustion air inlet, the inner face of the flexible panel being inclined downwardly from said upper side portion and across the radiant heat discharging port to be swept clear of dust and continuously cooled by incoming combustion air being supplied from the inlet to the radiant; and

means securing said flexible panel to the housing.

2. The space heater according to claim 1 and the radiant heat discharging port being broad and exceeding the size of the radiant.

3. The space heater according to claim 1 and the housing being inclined and having upper and lower end portions, the radiant and the radiant heat discharging port being disposed adjacent the lower end portion, and the gases discharging outlet being disposed adjacent the upper end portion of the housing.

4. The space heater according to claim 3 wherein the inclined housing and the inclined flexible panel are inclined in the same direction, the housing having an inclination at least as steep as the panel.

5. The space heater according to claim 1 wherein the housing has a rounded transverse shape, the radiant heat discharging port extending transversely through a significant portion of the housing periphery, the flexible panel having a rounded transverse shape similar to the transverse shape of the housing.

6. The space heater according to claim 1 wherein the housing has a rectangular transverse shape, the radiant heat discharging port extending transversely across the bottom of the housing, and the flexible panel being pulled taut across the port.

7. The space heater according to claim 5 and the flexible panel being taut in the longitudinal direction to smoothly directing combustion air flowing thereover.

8. The space heater according to claim 5 and the radiant having a downwardly facing and substantially flat flame heated radiating face, the spacing and angle of confrontation between various areas of the transversely rounded flexible panel and the flat radiating face of the radiant varying to vary the infrared applied to and through the panel.

9. The space heater according to claim 1 and a combustion air supply duct connected with said air inlet.

10. The space heater according to claim 9 and said duct being formed integrally of and in one piece with said flexible panel.

11. The space heater according to claim 9 and said duct incorporating a plenum chamber adjacent the air inlet and smoothing the flow of combustion air across the panel.

12. The space heater according to claim 1 and resiliently stretchable means securing the flexible panel to the housing and drawing the panel taut across the radiant heat discharging port.

13. The space heater according to claim 5 and resiliently stretchable means on the housing and connected to the upper end of the flexible panel and extending longitudinally of the elongate housing and drawing the panel taut across the port.

14. A fuel space heater, comprising:

a flame heated source of infrared;

a housing defining a combustion chamber with said source of infrared confined therein, the housing also having a heat exchange chamber adjacent to, above and in open gas flow communication with the combustion chamber, the housing having walls of heat-conductive material adjacent the heat exchange chamber, the housing having an infrared discharge port opening in a downward direction from the combustion chamber, and a combustion air inlet adjacent one side of the port; and

an inclined panel of infrared translucent material underlying and obstructing said port, one upper edge portion of the inclined panel being disposed adjacent said air inlet to receive cooling air downwardly across the inclined panel.

V UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No, 3, 424 r Dated Invenmfls) J hn E Eich-enlaub It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown belpw:

In Claim 14, line 29, after "fuel" insert-fire d-'.

Signedv and sealed this 2nd day of 'July 1974,-

sBALj Attest: e

EDWARD M, FLETCHBRJR. QMARSHALL' DANN Attesting. Officer Commmis'sioner of Patents FORM nap-1050 (10,59)

Claims

1. A fuel fired space heater, comprising: a flame heated radiant facing generally downwardly and directing infrared downwardly for heating such a space; an elongate enclosed housing defining a plenum chamber having a combustion portion encompassing said radiant and also having a combustion gases discharging portion adjacent to and at a superior elevation relative to said combustion portion, said discharging portion being in open and direct gas flow communication with the combustion portion of the plenum chamber, and the housing having a combustion gases discharging outlet communicating with the gases discharging portion of the plenum chamber and said outlet also being at a superior elevation relative to the combustion portion of the plenum chamber, the housing also having downwardly facing radiant heat discharging port disposed below said radiant and below the combustion portion of the plenum chamber, there being one lower side of the periphery of the port disposed at a lower elevation than the opposite upper side of the periphery of the port; a thin flexible inclined panel of material highly transmissive of infrared and confronting and obstructing the entire radiant heat discharging port, the side portions of the panel being in close fitting and substantially sealing relation with the sides of the periphery of the radiant heat discharging port, the upper end of the inclined panel being in spaced and confronting relation with and beneath the housing adjacent the upper side of the periphery of the radiant heat discharging port and cooperating with the housing to define a combustion air inlet, the inner face of the flexible panel being inclined downwardly from said upper side portion and across the radiant heat discharging port to be swept clear of dust and conTinuously cooled by incoming combustion air being supplied from the inlet to the radiant; and means securing said flexible panel to the housing.

14. A fuel space heater, comprising: a flame heated source of infrared; a housing defining a combustion chamber with said source of infrared confined therein, the housing also having a heat exchange chamber adjacent to, above and in open gas flow communication with the combustion chamber, the housing having walls of heat-conductive material adjacent the heat exchange chamber, the housing having an infrared discharge port opening in a downward direction from the combustion chamber, and a combustion air inlet adjacent one side of the port; and an inclined panel of infrared translucent material underlying and obstructing said port, one upper edge portion of the inclined panel being disposed adjacent said air inlet to receive cooling air downwardly across the inclined panel.