COMPACT FORCED AIR HEATER

Abstract: A compact, gas fired, forced air heater (10) has a burner module (26) mounted adjacent a squirrel cage blower (28) in the housing (11) of the heater. The horizontally firing burner module (26) icludes a burner tube (68) which has a flattened end (70) to aid in locating and orienting the tube, a flame holder plate (42) with secondary air holes (46) surrounding the central primary air hole (44), which in turn is concentric with the burner tube orifice (74), and a flamespreader plate (52) mounted opposite the burner tube orifice (74) such that the flameholder plate (42) lies therebetween, and the flamespreader plate (52) is in coaxial alignment with the burner tube orifice. The corners of the flame holder plate (42) may be bent to form ears (50) to help anchor the flame and enhance mixing. The housing (11) may include a heat reflector (16r) to reduce radiant heat loss through the housing (11).

Description: COMPACT FORCED AIR HEATER BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a forced air heater, and more particularly to a compact, inexpensive forced air heater of the direct gas-fired, portable type which provides higher heating efficiency, cleaner combustion and has a significantly improved BTU output capacity per unit volume in comparison to prior known heaters. Description of the Prior Art Numerous types of gas-fired air heaters have been developed and are known in the art. The most common type is typically tubular in shape, wherein- a motor-driven fan ushes air through a burner combustion chamber and out of a heater exit, as disclosed in the U.S. Patent No. 4,244,349 issued to W.W. Velie on January 13, 1981. A less common type is of a box-shaped configuration, rather than tubular, wherein air is pulled, rather than pushed, through the combustion chamber. These latter units use a forced air blower, rather than a fan, because a blower incorporates a blower housing which isolates the blower motor from the hot gases produced in the combustion chamber. These latter style heaters have more specialized applications where such items as flame containment, low noise and/or better heat distribution are important. The development goal for such heaters is to optimize size, performance and cost. For example, a known heater of this type is manufactured by the National-Riverside Company, a Division of Scheu Products Company, Incorporated of Rancho Cucamonga California, the assignee of the subject application, as their model 60FA-BE forced air propane gas portable heater. In this connection, the purpose of this invention is to provide an improved small forced air gas heater of this type which has significantly improved BTU output per cubic inch of size, is lower in cost, easier to service, and simpler in construction, and which provides more efficient heating, cleaner combustion and quieter operation. Summary of the Invention In general, a compact forced air heater in accordance with the invention comprises a combustion chamber mounted in a housing, a burner module mounted across a back open end of the combustion chamber adjacent a back wall of the housing, for introducing fuel, mixing fuel and air, igniting the fuel mixture and stabilizing the flame in the combustion chamber, and an air intake in a front wall of the housing. A forced ai blower is located between the combustion chamber and the housing front end wall for drawing air through the air intake and the housing in one direction into a rear space in back of the combustion chamber, and then past and through the burner module in an opposite direction into the combustion chamber; drawing heated air produced in the combustion chamber by the burner module out of the combustion chamber; and exhausting the heated air into a space to be heated. The burner module, which is of special construction, includes a flameholder plate mounted across the back open end of the combustion chamber and having a large central primary air hole and secondary air holes surrounding the primary air hole. A flamespreader plate is mounted on the flameholder plate opposite the primary air hole, and an elongated burner tube is located adjacent an opposite side of the flameholder plate and has at least one burner orifice in a sidewall of the tube in alignment with the primary air hole and the flamespreader plate. The flameholder plate also includes an igniting device for igniting fuel emanating from the burner orifice of the burner tube after it has mixed with air in the vicinity of the flamespreader. More specifically, the secondary air holes may form one or more circular rows or concentric circles located outside an imaginary line on the flameholder plate defined by extending a periphery of the flamespreader plate axially to the flameholder plate, with the holes in each alternating row in staggered relationship to the holes in the adjacent row(s) . A closed end of an end section of the elongated burner tube, which includes the burner orifice, is of a flattened configuration and is secured onto the flameholder plate to orient the burner orifice into alignment with the primary air hole in the flameholder plate and the flamespreader plate. The burner tube also includes an inlet section extending from the end section for connection to a fuel control valve adjacent the housing front end, with the end and inlet tube sections being integrally connected by an intermediate tube section. Corners of the flameholder plate may be bent obliquely or directly downstream with respect to the air flow into the combustion chamber, to enhance the mixing of the flame and the combustion air so as to provide cleaner combustion. Preferably, the forced air blower has a high speed, on the order of at least 3,000 rpm, and air flow about the flameholder plate into the combustion chamber is above approximately 1200 fpm. Brief Description of the Drawings Figure 1 is an isometric exploded view of a compact forced air heater in accordance with the invention; Figure 2 is a cross-sectional view of the compact forced air heater shown in Figure 1, in an assembled condition Figure 3 is a partial isometric exploded view of the back end of the compact forced air heater shown in Figure 1; Figure 4 is a partial rear elevational view of the embodiment of the invention shown in Figure 3; Figure 5 is a cross-sectional view taken along the line 5-5 of Figure 4; Figure 6 is a cross-sectional view taken along the line 6-6 of Figure 4; Figure 7 is a partial isometric exploded view of another embodiment of the invention; Figure 8 is a partial rear elevational view of the embodiment of the invention shown in Figure 7; Figure 9 is a cross sectional view taken along the line 9-9 in Figure 7; and Figure 10 is a cross sectional view taken along the line 10-10 in Figure 7. Detailed Description of the Drawings In general, referring to Figures 1 and 2 of the drawings, a forced air heater 10 in accordance with the invention includes an outer housing 11 having a top wa l 12 integrally connected to two sidewalls 14, a front end plate 15, a rear end plate 16 and a base plate 18. The heater 10 is of a .portable type and includes a carrying handle 20 provided on the top wall 12. The front plate 15, having an air intake screen 21 secured thereon, is mounted at the front end of the housing 11 and a power cord 22 (Figure 1) extends into the housing 11 through the front end plate 15. The integrally connected top wall 12 and sidewalls 14 are secured to the base plate 18, front end plate 15 and rear end plate 16 by screws. As described above, the forced air heater 10 is of a generally known type. However, in accordance with this invention, the forced air heater 10 is of a smaller more compact configuration (e.g., 12 x 7 x 9 inches) which produces a BTU output per cubic inch on the order of 2 1/2 times that of prior known heaters (e.g., 40 BTU per cubic inch versus 16 BTU per cubic inch.) More specifically, the heater 10 further includes a rear combustion chamber 24, a burner module or assembly 26 mounted across the back of the combustion chamber, and a forced air blower 28 mounted within the housing 11 on the base plate 18 between the combustion chamber and the front end plate 15. The general flow of air through the heater 10, when the heater is in operation, is indicated by arrows in Figure 2, namely, from the air intake 21 through the housing 11 above the blower 28 and the combustion chamber 24 in one direction to a rear space 29 behind the combustion chamber, and then in an opposite direction past and through the burner module 24 into the combustion chamber. The rear end plate 16 of the housing 11 also has a metal heat reflector 16r mounted thereon, to reflect outwardly radiating heat back into the housing. The combustion chamber 24 is of essentially box-shape construction and includes a top wall 30, sidewalls 32 and fron and back open ends 36. The burner module 26 is mounted across the back open end 36 of the combustion chamber 24 in a vertica position. The air velocity around the burner module 26 into the combustion chamber 24 preferably is above 1200 ft./minute; therefore, the capacity of the forced air blower 28, and the size of the spaces between the outer dimensions of the combustion chamber 24 and the housing 11, and between the combustion chamber and the burner module 26, are important, and are chosen so that flow passage between the combustion chamber and a flameholder plate 42 of the burner module 26 attains such a velocity. The combustion chamber 24 also acts as a conduit between the burner module 26 and the blower 28, and must be of a length sufficient to accommodate a complete combustion process. The flameholder plate 42 of the burner module 26 is of a configuration which allows the flame size to be reduced, while maintaining good combustion performance and a relatively low sound level. In this regard, the flameholder plate 42 may be of square or circular configuration, having a large central primary air hole 44, and a plurality of secondary air holes 46 formed therein in the shape of one or more circular rows for the passage of air therethrough. The flameholder plate 42 also is provided at its corners with mounting brackets 48 for securing the flameholder plate in a vertical position to the walls 30, 32 of the combustion chamber 24 and the housing base plate 18- Preferably, for best performance the diameter of the pximary air hole 44 is between 0.5 and 0.75 inches, and the secondary air holes 46 have a diameter of approximately 1/8 inch" and are spaced approximately 0.3 inch apart. The secondary air holes 46 in alternate circular rows are staggered with respect to the air holes in the adjacent row(s), as is best shown in Figures 1 and 5. The flameholder plate 42 also has ears 50 formed by bending plate corners downstream with respect to air flow into the- combustion chamber 24 and outward at about 45°, and then aqaHLXL downstream and inwards at about 90°, in a V-shaped conf£guxation consisting of an inner larger segment and a SHralleir tip segment. This bending is such as to place the ears 533 ini the path of the flame generated by the burner module 26, causing the ears to act as afterburners and thereby improve combustion cleanliness and properly direct tertiary combustion air. The ears 50 also increase the turbulence of the air around the burner module 26 to enhance the mixing of the flame and the combustion air. In addition, the ears 50 partially block corners 51 (best shown in Figure 4) between the flame holder plate 42 and the combustion chamber back open end 36 to force air to flow through the primary air hole 44 and the secondary air holes 46, and also to confine this air in the vicinity of the flame, thereby creating turbulence which enhances fuel-air mixing to provide more complete combustion. At the same time, the unblocked portions of the combustion chamber corners 51 permit air to flow around the flameholder plate 42 to provide tertiary air for combustion and cooling. In other words, there should be a balance of air through the primary air hole 44 and the secondary air holes 46 to the flame, and around the flameholder plate 42 at the combustion chamber corners 51. A flamespreader plate 52 is mounted on an inner side of the flameholder plate 42 opposite the primary air hole 46 by a bracket member 54 having the flamespreader plate secured to a central portion thereof, and having opposite leg portions suitably secured to the flameholder plate. Preferably, the diameter of the flamespreader plate 52 is between 1.5 and 2.5 inches, and the axial spacing of the flamespreader plate from the flameholder plate 42 is between 0.5 and 0.75 inches. The first circular row of secondary air holes 46 should have .a greater diameter than the flamespreader plate 52, such as a diameter of approximately 2.25 to 2.75 inches (i.e., the first circular row will be located outside an imaginary line defined by extending a periphery of the flamespreader plate 52 axially to the flameholder plate 42). The outermost peripheral dimension (i.e., maximum transverse direction or diameter) of the flameholder plate 42 should be 30-40% larger than the diameter of the outermost circular row of the secondary air holes 46. Larger heaters 10 may have more circular rows; however, too many rows will cause poorer performance and, therefore, the number of rows for a particular size flameholder plate 42 is critical. The burner module 24 further includes an ignitor electrode 56 and a flamesensor 58 suitably mounted on the flameholder plate 42. The ignitor electrode 56 may be a direct spark device located closely adjacent the flamespreader plate mounting bracket 54, and wired by a lead 60 to a terminal box 62 at the front of the heater 10, so as to be energized automatically when the heater is plugged into an electrical source. The flamesensor 58 functions as a flame sensing device for maintaining a fuel control valve 64 at the front of the heater 10 open when the flame is present. The control valve 64 is connectable to a suitable gas fuel source (not shown) by a fitting 67. The burner module 26 further includes an elongated burner tube 68 having an open end provided with a fitting 68f (Figure 2) for connection of the burner tube to a fitting 69 of the control valve 64. As is best shown in Figures 4 and 6, the elongated burner tube 68 also has a closed flattened end 70 which includes a longitudinally extending mounting portion 70a, a longitudinally extending portion 70b, and a right-angle spacer portion 70c. The mounting portion 70a is secured to th outer side of the flameholder plate 42 by a screw 72. Referring to Figure 6, the elongated burner tube 68 i provided with at least one burner orifice 74 in a sidewall of the tube and in alignment with the central primary air hole 44 in the flameholder plate 42. The elongated burner tube 68 als includes a first end section 68a, which includes the closed flattened end 70 and the burner orifice 74, a second elongated inlet section 68b, which includes the fitting 68f, and a curved, right-angle intermediate tube section 68c connecting the first and second sections. In a preferred embodiment, the axial spacing of the burner orifice 74 of the tube 68 from the hole in the flameholder plate 42 is from 0.4 to 1.0 inches. Adjacent one edge of the flameholder plate 42, a channel-shaped member 76, having a laterally projecting mounting flange, is secured to the flameholder plate, such as by rivets 78, so that the first end section 68a of the elongated burner tube 68 is received in a seat formed by the channel-shaped member. Thus, the mounting section 70a at the flattened end 70 of the elongated burner tube 68, and its associated screw 72, and the channel-shaped member 76, cooperate to ensure proper alignment of the elongated burner tube, to locate the burner orifice 74 of the tube in proper position on the flameholder plate 42 in alignment with the central primary air hole 44 therethrough and in opposed relationship to the flamespreader plate 52. Referring again to Figures 1 and 2, the forced air blower 28, which is of a known type, includes a housing 84 having an open air-intake opening 86 (Figure 2) located essentially centrally of the combustion chamber 24, and a discharge opening 88 (best shown in Figure 1) which is aligned with a discharge opening 90 (Figure 1) in one of the sidewalls 14 of the outer housing 11. The blower 28 further includes an annular-shaped blower wheel 92 (Figure 1) within the housing 84. The blower wheel 92 is located in the blower housing 84 essentially centrally of the combustion chamber 24 so as to draw heated air from the combustion chamber into the blower housing, and then discharge the heated air through the blower housing discharge opening 88 and the outer housing discharge opening 90 into the space to be heated. The blower housing 84 is directly supported on the base plate 18 and secured thereto by screws, not shown, and is secured to the housing sidewall 14 and the combustion chamber top wall 30, by mounting brackets 95 A blower drive motor 96 is supported on a closed end wall of the blower housing 84 on an opposite side thereof from the blower wheel 92, and includes a drive shaft 98 (Figure 2) on which the blower wheel is supported, and leads 100 connectable to suitable terminals (not shown) . For compactness, the wheel 92 should operate at high speed, having a speed above 3000 rprn, as compared to prior art heaters of this type, which use blower wheel speeds of about 1500 rpm. Further, as is indicated by the arrows at the left-hand side o Figure 2, during operation of the heater 10, the blower device 28 causes relatively cool ambient air to be drawn into the housing 11 through the air-intake screen 21 upward past the blower drive motor 96, prior to the air entering the combustio chamber 24, thereby simultaneously cooling the motor when the heater is in operation. Figures 7-10 disclose another embodiment of the invention essentially as disclosed in my copending application Serial No. 029,010, filed March 23, 1987, the disclosure of which, to the extent not inconsistent with this disclosure, is hereby incorporated by reference. In this embodiment of the invention, a burner module or assembly 26' of a slightly different configuration is mounted on the back of a combustion chamber 24', in place of the burner module 26 as in the embodiment of the invention shown in Figures 1-6. The burner module 26' includes a flameholder plate 42' of square configuration, having a large central primary air hole 44' and smaller secondary air holes 46' formed therein for the passage of air therethrough. The flameholder plate 42' also is provided at its corners with mounting brackets 48' for securing the flameholder plate to walls of the combustion chamber 24' and a housing base plate 18' (Figure 8). Further, the flameholder plate 42' has ears 50' bent downstream and then inward at about 135° to place the ears in the flame generated by the burner module 24', causing the ears to act as afterbntrners to improve combustion and combustion cleanliness. A flamespreader plate 52' is mounted on an inner side of the flameholder plate 42' by a bracket member 54' having the flamespreader plate secured to a central portion thereof, and having opposite leg portions suitably secured to the £lamer_Qlder plate. The burner module 24' further includes an irrπitαr 56' and a thermocouple 58' suitably mounted on the flameholder plate 42 ' . The embodiment of the invention shown in Figures 7-10 further includes an elongated burner tube 68' having an open fxont end provided with a fitting (not shown) for connection of t e_ burner tube to a control valve (not shown) . As is best sliowrr in Figures 8 and 10, the burner tube 68' has a closed fLatte-ned opposite end 70' which includes a mounting portion 7u_=t-"„ a longitudinally extending portion 70b', and a rigiit:—angle spacer portion 70c'. The mounting portion 70a" is seeuxed to the outer side of the flameholder plate 42' by a screw 72' : Referring to Figure 10, the elongated burner tube 68' is provided with a single burner orifice 74' in a sidewall of the tube and in alignment with the central primary air hole 44' in the flameholder plate 42'. The elongated burner tube 68' also includes a first section 68a', which includes the closed flattened end 70' and the single burner orifice 74', a second elongated section 68b', which includes the abovementioned fitting (not shown), and a curved right-angle section 68c' interconnecting the first and second sections. Adjacent one edge of the flame holder plate 42*, a channel-shaped member 76', having a laterally projecting mounting flange, is secured to the flameholder plate, such as by rivets 78', so that the first section 68a' of the elongated burner tube 68' is received by a seat formed by the channel-shaped member. Thus, the mounting portion 70a' at the flattened end 70' of the elongated burner tube 68', and its associated screw 72', and the channel-shaped member 76', cooperate to ensure proper alignment of the elongated burner tube, to locate the single burner orifice 74' of the tube in proper position on the flameholder plate 42' in alignment with the central aperture 44' therethrough and in opposed relationship to the flamespreader plate 52'. In summary, applicant has provided a new and improved forced air-type portable heater 10 which is of very compact simplified construction, has greater heating efficiency, and efficient combustion, and in which intake air.is used to eliminate hot spots in the heater, to achieve a significantly improved BTU output per cubic inch on the order of 2 1/2 times that of prior known heaters. The heater 10 includes the air intake 21, the high speed forced air blower 28 and the combustion chamber 24 arranged sequentially from the front to the back thereof, with the burner module 26 arranged vertically in the back open end of the combustion chamber and spaced from the heat reflective surface 16r on the rear housing wall 16. Thus, the forced air blower 28 can draw air into the housing 11 through the air intake 21, past the blower drive motor 96 to the rear space 29 in the housing in one direction, and then in a reverse direction into the combustion chamber 24 past and through the burner module 26, for combustion. The heated air then is drawn from the combustion chamber 24 by the blower 28 and exhausted through the housing opening 90 into the space to be heated. Further, the burner module 26 is of a unique construction, comprising the flameholder plate 42 provided with the central primary air hole 44 surrounded by the circular rows of staggered secondary air holes 46, and the elongated right-angle bent burner tube 68 having the flattened mounting and orienting portion 70a for locating the burner orifice 74 in alignment with the primary air hole 44 and the flamespreader plate 52. The flameholder plate 42 also includes the inwardly bent ears 50 which function as afterburners and facilitate air circulation to enhance the combustion process. The net result is a forced air heater of a smaller, more compact configuration which produces a BTU output per cubic inch on the order of 2 1/2 times that of prior known heaters.

Claims: WHAT IS CLAIMED IS: 1. A compact forced air heater, which comprises: a housing; a combustion chamber mounted in said housing and having a back open end; a burner module mounted across the back open end of said combustion chamber adjacent a back end wall of said housing, for introducing fuel, mixing fuel with combustion air igniting said fuel-air mixture and stabilizing the resulting flame in said combustion chamber; an air intake in a front wall of said housing; a forced air blower means between said combustion chamber and the front wall of said housing, for drawing air through said air intake and through said housing in one direction into a rear space in back of said combustion chamber, and then in an opposite direction past and through said burner module into said combustion chamber, said forced air blower means also drawing heated air from said combustion chamber, and exhausting the heated air into a space to be heated. 2. The compact forced air heater as recited in claim '1, wherein said forced air blower means has a speed of at least 3,000 rp . 3. The compact forced air heater as recited in claim 1, wherein said back end wall of said housing includes a heat reflecting member for reflecting outwardly radiating heat back into said housing. 4. The compact forced air heater as recited in claim 1, in which said burner module comprises: a flameholder plate mounted across the back open end of said combustion chamber, said flameholder plate having a large central primary air hole and a plurality of smaller secondary air holes surrounding the primary air hole; a flamespreader plate mounted adjacent one side of said flameholder plate opposite the primary air hole; a burner tube located adjacent an opposite side of said flameholder plate and having at least one burner orifice in a sidewall of the tube in alignment with the primary air hole and the flamespreader plate; and igniting means for igniting fuel emanating from the burner orifice and passing through the flame holder plate adjacent to the flame spreader plate. 5. The forced air heater as recited in claim 4, in which: said flameholder plate has peripheral portions spaced from wall portions of said combustion chamber; and said air blower means produces, air flow between said flameholder plate peripheral portions and said combustion chamber wall portions, from said rear space in said housing into said combustion chamber, at a rate above approximately 1200 fpm. 6. The compact forced air heater as recited in claim 4, in which said burner tube further comprises: a flattened end portion on a first end section downstream of said burner orifice, said flattened end portion being mounted against said flameholder plate to orient the burner orifice into alignment with the primary air hole in sai flameholder plate; and an elongated second inlet section extending upstream of said burner orifice and having a fuel coupling fitting at one end thereof, said first end section and said second inlet section being integrally connected by an intermediate burner tube section. 7. The compact forced air heater as recited in claim 4, in which the secondary air holes in said flameholder plate are located outside an imaginary line on said flameholder plate defined by extending a periphery of said flamespreader plate axially to said flameholder plate. 8. The forced air heater as recited in claim 7, in which the secondary air holes in said flameholder plate are located in circular rows about the central primary air hole in the plate. 9. The compact forced air heater as recited in claim 4, in which the spacing of the burner orifice in said burner tube from the central primary air hole in said flameholder plate is in range on the order of 0.4 to 1.0 inches. 10. The compact forced air heater as recited in claim 9, in which: said flamespreader plate has a diameter in a range on the order of 1.5 to 2.5 inches; the central primary air hole in said flameholder plate has a diameter in a range on the order of 0.5 to 0.75 inches; the spacing of the central primary air hole in said flameholder plate from said flamespreader plate is in a range on the order of 0.5 to 0.75 inches; the secondary air holes in said flameholder plate are approximately 1/8 inch in diameter and approximately 0.3 inch apart, with the secondary air holes in alternate rows staggered with respect to one another; the inner circular row of secondary air holes in said flameholder plate has a diameter on the order of 2.25 to 2.75 inches; the outer circular row of secondary air holes in said flameholder plate has a diameter in a range on the order of 3.5 to 6.0 inches; and said flameholder plate has a periphery located from the center of the plate a distance on the order 30 to 40% larger than the diameter of the outer circular row of secondary air holes. 11. The compact forced air heater as recited in claim 4, in which said flameholder plate has peripheral portions bent over in a direction extending from said burner tube toward said flamespreader plate to promote mixing and to function as afterburners. 12. The compact forced air heater as recited in clai 11, in which said flameholder plate bent-over portions are in two segments, said segments including a larger segment which i inclined from the plate, and then a smaller tip segment which is bent inward relative to said larger segment and forming a V-shaped con iguration. 13. A burner module for a forced air gaseous fuel heater, which comprises: a flameholder plate, said flame holder plate having a large central primary air hole and a plurality of smaller secondary air holes surrounding the primary air hole: a flamespreader plate mounted adjacent one side of said flameholder plate and concentric with the primary air hole; a burner tube, said burner tube being located adjacent to the flame holder plate but on an opposite side of said flameholder plate from the flame spreader plate and having at least one fuel orifice in alignment with and perpendicular to the primary air hole and said 'flamespreader plate; and igniting means for igniting fuel emanating from the fuel orifice of said burner tube. 14. The burner module as recited in claim 13, wherein said burner tube further comprises: a flattened end portion on a first end section downstream of the fuel orifice, said flattened end portion being mounted against said flameholder plate to orient the fuel orifice with respect to the central primary air hole in said flameholder plate; and an elongated second inlet section extending upstream of said orifice and having a fuel coupling fitting at one end thereof, said first end section and said second inlet section being integrally connected by an intermediate burner tube section. 15. The burner module as recited in claim 13, in which the secondary air holes in said flameholder plate are located outside an imaginary line on said flameholder plate defined by extending a periphery of said flamespreader plate axially to said flameholder plate. 16. The burner module as recited in claim 15, in which the secondary air holes in said flameholder plate are located in circular rows about the central primary air hole in the plate. 17. The burner module as recited in claim 13., in which the spacing of the burner orifice in said burner tube from the central primary air hole in said flameholder plate is in a range on the order of 0.4 to 1.0 inches. 18. The burner module as recited in claim 17, in which: said flamespreader plate has a diameter in a range on the order of 1.5 to 2.5 inches; the central primary air hole in said flameholder plate has a diameter in a range on the order of 0.5 to 0.75 inches; the spacing of the central primary air hole in said flameholder plate from said flamespreader plate is in a range on the order of 0.5 to 0.75 inches; the secondary air holes in said flameholder plate are approximately 1/8 inch diameter and approximately 0. inch apart, with the secondary air holes in alternate rows staggered with respect to one another; the inner circular row of secondary air holes in said flameholder plate has a diameter on the order of 2.25 to 2.75 inches; the outer circular row of secondary air holes in said flameholder plate has a diameter in a range on the order of 3.5 to 6.0 inches; and said flameholder plate has a periphery located from the center of the plate a distance on the order 30 to 40% larger than the diameter of the outer circular row. of secondary air holes. 19. The burner module as recited in claim 13, wherein said flameholder plate has peripheral portions bent over in a direction extending from said burner tube toward said flamespreader plate to function as combustion enhancers and afterburners. 20. The burner module as recited in claim 19, wherein said flameholder plate bent-over portions are in two segments, said segments including a larger segment which is initially inclined from the plate and then a smaller tip segment which is bent inward relative to said larger segment and forming a V-shaped configuration.

Inventors: VELIE WALLY W, VELIE, WALLY, W.
Applicants: SCHEU MFG CO, SCHEU MANUFACTURING COMPANY
Application year: 1988
Main classification: F24H3
IPC codes: F23D14, F24H3