A gas burner of the atmospheric type for water heating appliances, particularly heaters of the so-called instant type

Abstract: A gas burner (1) of the atmospheric type for water heaters comprises a plurality of flame diffusers (2) arranged at a common level in parallel flame rows and in fluid communication with at least one header conduit (6,7) provided at the top with plural flame passageways (8) extending through a top wall (6a,7a) thereof and being substantially coplanar with the diffusers (2). The burner (1) allows of correct mutual ignition of the flames upon starting and has advantageous simple construction features.

Description: This invention relates to a gas burner of the atmospheric type, intended for use in water heating appliances and comprising a plurality of flame diffusers arranged to lie at a common level in parallel flame rows. The expression "gas burner of the atmospheric type" means here a device in which the theoretical combustion air is partly pre-mixed with the fuel gas at the burner inlet by the gas flow (primary air) and partly fed to the flames (secondary air) by natural draft. As is known, gas burners of the atmospheric type are widely used in water heating appliances, such as home water heaters or boilers of the so-called instant type for heating sanitary water and/or interior spaces. Of such atmospheric type gas burners, the so-called "element burners" are preferred for use in that field. Element burners comprise a plurality of flame diffusers which are flattish in shape and arranged to lie at a common level in parallel flame rows. The diffusers are either packed on suitable frames or welded crosswise to a feed header tube which also carries a mixing device such as a Venturi nozzle. While such burners provide a uniform flame bed in operation, on starting they not infrequently develop problems from unreliable mutual ignition. This mutual ignition i.e. propagation of the flame from one diffuser to the next at the start of the burner operation, takes place in a somewhat erratic fashion giving rise to a typical "backflash". In addition, burners of this type carry comparatively high manufacturing costs due to they being material intensive and involving complicated assembly procedures. An example of such prior art is known from FR-A-1492997. The underlying technical problem of this invention is, therefore, to provide a gas burner of the atmospheric type, which affords correct mutual ignition of the flames on starting, as well as being low in cost and easy to assemble. This problem is solved according to the invention by a burner as indicated being characterized in the appended claims. With the individual flame rows of the diffusers interconnected by the flame passageways provided by the header conduit, the difficulties of mutual ignition which typically affect similar state-of-art devices are eliminated altogether. Further, for a given bulk, the burner of this invention can deliver a higher thermal power which will be proportional to the increased volume flow rate of the gas/air mixture issuing from the header conduit. Further features and advantages of a gas burner according to the invention will become apparent from the following description of a preferred embodiment thereof, given by way of example with reference to the accompanying drawings. In these drawings: Figure 1 is a plan view of a gas burner of the atmospheric type according to the invention; Figure 2 shows the burner of Figure 1 in a lognitudinal section taken along line II-II in Figure 1; Figure 3 is an enlarged detail view of Figure 2; Figure 4 is a cross-sectional view of the burner shown in Figure 1, taken along line IV-IV in Figure 1; Figure 5 is a further cross-sectional view of the burner shown in Figure 1, taken along line V-V in Figure 1; and Figure 6 is an enlarged-scale detail view of Figure 5. With reference to the drawing figures, generally shown at 1 is a gas burner of the atmospheric type according to this invention. The burner 1 comprises a box-type body 3 formed conventionally by joining together, as by seam folding, two juxtaposed metal sheets which have been dished to respectively define a top portion 4 and a bottom portion 5 of the burner. Formed in the box-type body 3 of the burner 1 are a plurality of flame diffusers 2 arranged to lie at a common level and in parallel flame rows. Provided between the flame diffusers 2 are a plurality of slits 9, set at pitch distances apart and extending parallel to the diffusers, which slits are to function as passageways for the secondary combustion air. The flame diffusers 2, which are formed by suitably dishing the top 4 and bottom 5 portions of the burner 1, comprise a box-type body 12 having at the top plural openings 15, with each opening constituting one flame passageway. In addition, each box-type body 12 has a partition 13 fixed therein which is through-penetrated by holes 14 and allows even delivery of a gas/air mixture to the openings 15. The diffusers 2, being formed at mutual spacings, are in fluid communication with two header conduits 6, 7 which extend across them and are formed by suitably dishing the top 4 and bottom 5 portions of the burner. Each header conduit 6, 7 is provided upwardly with plural openings 8 constituting as many flame passageways and extending through a top wall 6a, 7a thereof. It is a characteristic feature of this invention that the walls 6a and 7a, and hence the flame passageways 8, are substantially coplanar with the diffusers 2. As can be gathered from Figure 6, the conduits 6, 7 are also formed by suitably dishing the top 4 and bottom 5 portions of the burner 1. In a preferred embodiment of the invention, a partition 10. through-penetrated by holes 11, is fixed inside each header conduit 6, 7 in the region of the joint between the top 4 and bottom 5 portions of the burner 1. The burner 1 of this invention further comprises two mixing devices 16 and 17, e.g. of the so-called Venturi type, which are conventionally supported on the body 3 parallel to two intermediate flame diffusers 2. The mixing devices 16 and 17 include chambers 18, 19 carrying on their interiors respective Venturi nozzles in fluid communication with the conduits 6 and 7 through openings, all designated 21, formed in the side walls of the conduits. Of said nozzles, shown in Figure 4 is the one provided in the mixing device 16, as indicated at 20. The burner 1 of this invention, when run through repeated ignition tests, has shown none of the ignition faults which affect state-of-art gas burners of the atmospheric type. In operation, the burner 1 developed a most even flame bed and a very high thermal power for a given bulk. Additionally, the burner 1 of this invention is uniquely simple in construction, it incorporating to a single box-type body 3 both the flame diffusers 2 and the header conduits 6 and 7, each formed with its own flame passageways 8. This body 3 leads to advantageous lower costs by having just two stamped or dished metal sheets joined to each other as by a seam folding process. Of course, other manufacturing techniques and materials may be used to advantage for making the burner 1 or component parts thereof, such as an aluminum die-casting method. Advantageously, the construction of the body 3 of the burner 1 allows one or more gas/air mixing devices to be arranged either parallel or perpendicular to the flame diffusers 2, thereby making in either case for optimum utilization of the available space within each water heater unit. By using two or more gas/air mixing devices, moreover, it becomes advantageously possible to improve the burner flexibility to suit different operational conditions. In addition, the provision of perforated partitions 10 and 13 affords a more uniform distribution of the gas/primary air mixture and attendant less chance of backfiring. Finally, the constructional features of the burner 1 enable the dimensions, and hence the thermal power delivered by the burner, to be adjusted as desired by simply changing the number of the flame rows at the dishing stage.

Claims: A gas burner of the atmospheric type, for use in water heating appliances and comprising a plurality of flame diffusers (2) arranged to lie at a common level in parallel flame rows, characterized in that it comprises: at least two header conduits (6,7) extending across and in fluid communication with said flame diffusers (2), each of said header conduits (6,7) being provided at the top with a plurality of flame passageways (8) extending through a top wall (6a,7a) thereof and being substantially coplanar with said diffusers (2); and at least one gas/air mixing device (16,17) in fluid communication with said flame diffusers (2) and said at least two header conduits (6,7). A gas burner according to Claim 1, characterized in that it comprises a box-type body (3) consisting of two mutually associated portions, being respectively a top portion (4) and a bottom portion (5). A gas burner according to Claim 2, characterized in that it further comprises, placed between said top (4) and bottom (5) portions, a first partition (10) provided with throughgoing holes (11) and extending across said at least one header conduit (6,7). A gas burner according to Claim 2, characterized in that each flame diffuser (2) comprises a box-type body (12) provided at the top with a plurality of flame passageways (15). A gas burner according to Claim 4, characterized in that a second partition (13) provided with throughgoing holes (14) extends inside each box-type body (12) of said flame diffusers (2). A gas burner according to Claim 1, characterized in that said at least one gas/air mixing device (16,17) comprises a Venturi nozzle (20). A gas burner according to Claim 2, characterized in that said top (4) and bottom (5) portions are stamped or dished metal sheets.

Inventors: SCANFERLA GIORGIO, SCANFERLA, GIORGIO
Applicants: SCANFERLA GIORGIO, SCANFERLA, GIORGIO
Application year: 1993
Main classification: F23D14
IPC codes: F23D14