MXPA98010070A - Water heater ignited with gas that has an extreme bundle assembly of fund and removable pilot mounted in a pl - Google Patents

Abstract

The present invention relates to a water heater comprising: a tank adapted to maintain a quantity of water, a combustion chamber disposed below the tank and having a generally horizontal bottom side wall structure with a mounting aperture of burner extending upwards therethrough, a mounting plate structure secured below the bottom side wall structure, an apparatus for securing removably secured to the mounting plate structure towards the bottom side wall structure by above the burner mounting openings, a fuel burner secured to the mounting plate structure, to remove it downwards from the bottom side wall structure, and projecting above into the combustion chamber through of the burner mounting opening, a fuel valve device, a fuel supply line arranged externally to the combustion chamber and operatively connected directly to the fuel burner, a fuel supply line is removably coupled to the fuel valve device and prevent removal underneath the mounting plate structure of the wall structure bottom side and thus eliminating the fuel burner from the combustion chamber, to the fuel supply line that is uncoupled from the valve device, and an air intake path through which the combustion air can flow towards the combustion chamber

Description

WATER HEATER IGNITED WITH GAS THAT HAS AN EXTREME BUNDLE ASSEMBLY OF FUND AND OF REMOVABLE PILOT MOUNTED IN A PLATE. DESCRIPTION OF THE INVENTION The present invention generally relates to water heaters fired with fuel and, in a preferred embodiment thereof, more particularly provides a gas fired water heater having an end burner assembly incorporated therein. and of removable pilot mounted on a specially designed plate circumscribed through a combustion air intake structure of flame arrest. Residential and commercial gas-fired water heaters are generally formed including a vertical cylindrical water storage tank with a gas burner placed in a combustion chamber below the tank. The burner is supplied with a fuel gas through a gas supply line, and combustion air through one or more air inlet openings providing communication between the ambient air and the interior of the combustion chamber. Water heaters of this general type are extremely safe during operation. However, when gasoline or other flammable liquids are stored or used inappropriately near the water heater, there may be the possibility that flammable vapors will enter the air consumption of the water heater. There is a theory that such vapors can cause secondary combustion and that it occurs within the confines of the combustion chamber of the water heater. Accordingly, it is possible for the resulting flame to propagate out of the combustion chamber into the external environment around the water heater as a result of following the consumption path of the flammable vapor. In conventionally constructed water heaters of this general type, an access door to the combustion chamber is typically provided in a vertical side wall portion of the water heater, with heater and pilot gas supply lines extending horizontally through the the access door to the combustion chamber and connected to its associated burner and pilot structures within the combustion chamber. This access door design can possibly provide a potential leakage path between the combustion chamber and the exterior of the water heater. Another potential leakage path is presented by the inlet passage used to flow the combustion air into the combustion chamber. For water heater designs that focus on controlling the location of the entrance of flammable vapors that pass into the combustion chamber, it may be desirable to provide a sealed access structure for the combustion chamber and prevent the entry of flammable vapors to the combustion chamber through an inward flow path of unintended combustion air. The present invention is directed to these objects. In order to carry out the principles of the present invention, according to a preferred embodiment thereof, an improved water heater with fuel is provided. The water heater is representatively a gas-fired water heater, but alternatively it can be an oil-fired water heater, and includes an adapter tank to hold a quantity of water and a combustion chamber disposed below the tank and having a bottom side wall structure with a burner mounting opening extending up therethrough. A mounting plate structure is secured to the part below the bottom side wall structure, over the burner mounting opening, and is removed downwardly from the bottom side wall structure. Secured to the top side of the mounting plate structure for the downward removal with the same of the bottom side plate structure is a fuel burner, which projects upwards into the combustion chamber through the burner mounting opening in the bottom side wall structure. The burner is operatively connected to a fuel supply line which is disposed externally to the combustion chamber and which is removably coupled to a fuel valve device, representatively a thermostatic gas valve, mounted externally on the heater of water. A single seal element, illustratively an annular high temperature seal, is used to seal the mounting plate structure to the bottom of the bottom side wall structure. According to one aspect of the present invention, it is necessary to decouple the fuel supply pipe from the fuel valve device to remove the mounting plate structure from the bottom side wall structure and thus expose the opening of burner assembly. In this way, the burner mounting opening can not be covered while the burner is ignited. Further, when the mounting plate structure is replaced, its operational resealing to the bottom side wall structure of the combustion chamber can be more easily and reliably achieved by using an individual seal element interposed between the mounting plate structure and the structure of the side wall of the background. An air intake path is provided through which combustion air can be flowed into the otherwise sealed sealed combustion chamber, a portion of this air inlet path being defined by a series of separate openings formed in the bottom side wall structure, and preferably in the wall structure of the mounting plate as well. According to another aspect of the present invention, there are openings that act as flame suppressors to inhibit the external flow of the flames therethrough from inside the combustion chamber, which could possibly occur in the event that Flammable vapors passing up through the openings are ignited inside the combustion chamber during the water heater operation. The combustion air inlet openings disposed on the bottom side of the combustion chamber are dimensioned and configured to, (1) freely allow the flow of combustion air upwardly therethrough to the combustion chamber, and same time (2) prevent the external flow of the flames down through the combustion chamber inlet opening. Preferably, these openings have predetermined hydraulic diameter characteristics that cause a flame to pass down through them. Illustratively, the bottom side wall structure and the mounting plate structure, each being of steel construction and having a thickness of approximately 0.635 cm. (0.25 inches), each of the series of separate combustion air inlet openings has a generally circular cross section with a diameter of approximately 0.16002 cm. (0.063 inches), and the openings have a center-to-center gap of approximately 0.3175 cm. (0.125 inches). Preferably the bottom wall structure and the mounting plate structure, each is formed from a plurality of stacked perforated steel plates (representatively four in number), wherein the perforations are in register with each other to form in combination form the combustion air inlet openings. Alternatively, the bottom side wall structure and the mounting plate structure may be of a one-piece metal construction, and the combustion air inlet openings may be formed only in the bottom side wall structure. In a preferred embodiment thereof, the water heater further includes a hollow skirt structure extending down past the bottom wall structure and having a vertical side wall portion with a separate series of inlet openings formed therein to allow air to enter. of combustion into the interior of the hollow skirt structure to be supplied thereto to the combustion chamber through the combustion air inlet openings in the bottom side of the combustion chamber. Also in the preferred embodiment of the water heater, an insulating jacket structure circumscribes the tank. The insulating jacket structure has an outer wall portion with a lower end section that circumscribes the hollow skirt structure outwardly and defines therewith a full air inlet. The lower end section of this outer jacket wall has a separate series of air inlet openings therein which allows the combustion air to flow inward towards the plenum of air to supply from there to the interior of the structure of hollow skirt through the entry openings in its vertical side wall portion. The vertical side wall portion of the skirt structure and the outer jacket wall portion preferably have aligned access openings formed therein through a horizontal portion of the outwardly extending fuel supply line before returning to up to its coupling location on the thermostatic fuel valve. The mounting plate structure, the fuel burner and a portion of the fuel supply line are removed out through the access openings when the fuel supply line is decoupled from the thermostatic fuel valve and the structure of mounting plate is removed down from the bottom side wall structure of the combustion chamber. A suitable removable cover plate • is externally attached to the water heater to cover the access openings until removal of the fuel burner is desired. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a simplified partial cross-sectional view through a gas-fired water heater, modeling the principles of the present invention and having a burner and pilot assembly mounted at the bottom end, removable , circumscribed by an air intake structure to stop external flow of flames; Figure 1A is a view similar to that of Figure 1, but with a burner and pilot assembly removed downward from the lower end of the water heater; Figure 2 is an enlarged detail view of the circular shaded area "2" in Figure 1; Figure 3 is a detailed, enlarged view of the circular shaded area "3" in Figure 1; Figure 3A is a view similar to that of the Figure 3, but showing an alternative construction of a plate structure on which the burner and pilot assembly are mounted; and Figure 4 is a side elevation view of the water burner taken along line 4-4 of Figure 1. In Figure 1 illustrated in cross section, in simplified form being a lower end portion of a water heater. water fired with specially designed fuel 10, modalizing the principles of the present invention. Illustratively, the water heater ignited with fuel 10 is a gas-fired water heater, which uses gas, natural or liquefied petroleum, but alternatively it can be a water heater ignited with oil. The water heater 10 has a vertically oriented cylindrical metal water storage tank 12 where a quantity of hot water 14 is stored, the tank 12 having a head portion with an ascending dome bottom 16 which defines the upper wall of the tank. a combustion chamber 18, which communicates with the open lower end of a combustion flue pipe 20 which centrally extends upwardly through the interior of the tank 12. An annular external side wall portion of the combustion chamber 18 is defined by an annular lower end portion 12a of the tank, which extends downwardly beyond the periphery of the bottom head portion 16. In a conventional manner, suitable inlet and outlet pipes (not shown) are connected to the tank 12, to flow respectively hot water out of the tank and flow of water that will be heated in the tank. The lower end portion 12a of the tank 12 is supported above an annular shoulder structure 22 having an open lower end 24, which is received in a lower boiler member 26 which rests on a suitable horizontal support surface such as the indicated floor 28. A separate circumferential arrangement of combustion air inlet opening 30 is formed in the vertical side wall portion of the skirt structure 22 near the end of the bottom 24 of the skirt, and an access opening 32 is formed in the skirt 22 in a left portion thereof as seen in Figure 1. Circumscribing outside the tank 12 is a cylindrical insulating jacket structure 34, having an outer annular metal jacket portion 36 which is coaxial with tank 12 and is separated outwardly thereof. A suitable insulating material, such as a foam insulator 38, is disposed within the annular space between the metallic jacket portion 36 and the tank 12. The lower end of the metal jacket portion 36 is received within the lower cauld 26, and the insulation 38 has an annular bottom end surface 38a, which is spaced apart away from the lower end of the sleeve portion 36 and is vertically adjacent an inwardly turned annular flange 40 formed on the upper end of the skirt 22 (see Figure 2). The absence of the insulation 38 vertically along the skirt 22 forms an annular air consumption plenum space 42 between the skirt 22 and a lower end section of the sleeve portion 36. At the upper end of the plenum 42, a series circumferentially separate from air inlet openings 44 is formed in the sleeve portion 36. In addition, an access opening 46 is formed in the left side of the skirt 22 (as seen in Figure 1) and is aligned with the access opening 32 formed in the left lateral portion of the skirt 22. The bottom side wall of the combustion chamber 18 is positioned on the upper side of the skirt structure and is defined by (1) a perforated bottom side wall structure, annular 48 having a circular burner mounting hole 50, and (?) a circular perforated mounting plate structure 52. As best illustrated in FIG. 2, the bottom side wall structure 48 is positioned behind the rear wall. the skirt flange 40, with an annular high temperature sealing seal 54 which is interposed between a peripheral edge portion of the bottom side wall structure 48 and the flange of the skirt 40. This peripheral edge portion of the structure bottom side wall 48 is sealed to the underside of flange 40 through a circumferentially spaced array of screws 56 extending upwardly through the periphery of the bottom side wall structure 48, and flange 40, and compressing the seal 54. Preferably, the bottom side wall structure 48 is formed of a plurality of stacked annular perforated metal plates 58 (representatively four in number), with the perforations in the plates 58 being in register with one another to define in combination a separate series of vertical combustion air intake openings 60 extending vertically from the bottom side of the bottom side wall structure 48 towards its upper side. The illustrated openings 60 have circular cross sections along their lengths, but may alternatively have other transverse configurations. Since the bottom side wall structure 48 is illustratively formed through a stacked plurality of perforated plates, it will be appreciated that if desired, it may alternatively be formed of a single thicker plate. The mounting plate structure 52 extends along the central lower side portion of the bottom side wall structure 48 and covers the burner mounting hole 50 therein (see Figures 1 and 3). A high-temperature seal 62 is interposed between the peripheral portions of the mounting plate structure 52 and the burner mounting opening 50, with a circumferentially separate array of screw 64 extending upwardly through the overlapping peripheral portions of the screw. the bottom wall side structure 48 and the mounting plate structure 52 and compressing the joint 62 to form a peripheral seal between the bottom side wall structure 48 and the mounting plate structure 52. As the side wall structure ring background 48, the circular mounting plate structure 52 is formed of a stacked plurality of perforated plates 66 (representatively four in number), whose individual perforations are in register with each other to form in combination in the mounting plate structure 52, a separate series of combustion air consumption openings 60 extending vertically from the bottom side of the mounting plate structure 52 to its upper side. Alternatively, the perlolated mounting plate structure can be formed of a thicker, single metal plate with the openings 60 formed therethrough, or of a non-perforated mounting plate structure 52a as shown in the Figure 3A. A gas burner 68 and an associated pilot and thermocouple assembly 70 are suitably secured to and project upward from the upper side of the mounting plate structure 52 into the combustion chamber 18. To provide external visibility of the burner flame within the combustion chamber, a suitable visual glass structure of conventional construction (not shown) is provided on the water heater. A thermostatic gas supply valve 72, which checks the temperature of the stored water 14 and correspondingly controls the ignition of the burner 68, to maintain a water temperature in the predetermined tank, is mounted externally on the outer side of the structure of jacket 34 on the left side of the water heater 10 as seen in Figure 1. The thermostatic valve 72 receives a supply of gaseous fuel through a gas line 74 and is operatively coupled to (1) the burner 68 a through a gas supply pipe 7o, and (2) the pilot / thermocouple assembly 70 through a pilot gas line 78, the body 79 of the thermocouple portion of the assembly 70, and the electrical wiring (not shown) ). The gas lines 76 and 78, the thermocouple body 79 and the electrical wiring sequentially extend downwardly from the gas valve 72 outside the jacket structure 34, pass into the skirt 22 through the access openings to the jacket and skirt 46 and 32, and then extend upwardly through the mounting plate structure to connect to the burner 68 and the pilot / thermocouple assembly 70. In this way, the pipe and wiring are advantageously maintained outside the interior of the combustion chamber with heat 18. As best illustrated in Figure 4, a slotted cover plate 80 is movably secured to the outer side of the jacket structure 34 on the jacket access opening 46 to through flanges 82 formed on the upper side portions of the cover plate and removably locked with the corresponding flanges formed on the outer metal jacket portion 36. For purposes which will be described later, the bottom side portions of the aligned access openings 46, 32 (see Figure 4) are grooved as in 84.

As illustrated in Figure 1, during the operation of the water heater 10, while the burner 68 is turned on, the ambient combustion air 86 outside P adjacent to the water heater 10 is sequentially ejected inwardly through the air openings. shirt 44, down through the skirt / sleeve plenum area 42, inwardly through the skirt wall openings 30 towards the interior of the skirt 22, and upwards towards the combustion chamber 18 through the openings 60 in the bottom side wall structure 48 and the mounting plate structure 52. The air 86 entering the combustion chamber 18 is mixed and consumed with the fuel leaving the burner 68. The resulting hot combustion gases they flow through the flue pipe 20 and are used to supply heat to the tank water 14. When it becomes necessary to inspect, servicing or replacing the burner 68 and / or the pilot / thermocouple assembly 70, the cover plate 80 (see Figure 4) is removed and the pipes 76 and 78, the thermocouple body 79 and the associated electrical wiring (no. shown) are decoupled from the thermostatic gas valve 72. In addition, through the access openings in the jacket and the skirt 46 and 32, the screws 64 (see Figure 1) are removed from the mounting plate structure 52. Then, as indicated by the arrow 88 in Figure 1A, the mounting plate structure 52 is moved down from the bottom side of the bottom side wall structure 48, thereby lowering the mounting plate structure 52, the burner 68, the pilot / thermocouple structure 70 and the associated pipe 76, 78 and the thermocouple body 79 to their positions in Figure 1A. The aligned access openings 46, 32 are configured to allow downward movement of the horizontal portion of the gas supply pipe 76, with the bottom side notches 84 of said access openings receiving a horizontal portion of the pipe 76. Removed mounting plate, burner, pilot / thermocouple assembly and related piping structures can be pulled to the left out of aligned access openings 46, 32. Mounting burner 68 and pilot / thermocouple assembly 70 on the bottom side wall structure 48 of the combustion chamber 18, using the mounting plate structure 52, several advantages are obtained with respect to the conventional design of the water heater where access is provided to the combustion chamber through an access door, which is mounted on a vertical side wall portion of the combustion chamber.

First, these conventional vertically oriented access door structures are typically formed of several pieces, at least one of which is provided with openings for the main burner and the pilot gas line to pass through a horizontally central portion of the container. the combustion chamber. This placement and placement of the access door necessitates the use of various seal elements, which must be carefully installed when the water heater is manufactured, and then carefully replaced after subsequent service. to the burner and the pilot's structures. Using the lower mounted cover plate structure 52 of the present invention, however, only an individual seal (representatively, the seal member 62 shown in Figures 3 and 3A) is required. This makes it considerably easier to ensure that a good seal is maintained in the combustion chamber opening 50. Second, the conventionally configured combustion chamber access doors typically can be opened during burner ignition. inside the combustion chamber, thus communicating the flame of the burner with the environmental exterior towards the water heater. In the present invention, however, this condition can not occur since it is necessary to unclog the bottom side wall opening of combustion chamber 50 to decouple the gas pipe from the thermostatic gas valve 72, thus positively preventing the presence of a flame inside the combustion chamber when the opening 50 is uncovered. Third, as can be seen in Figure 1, in the present invention the gas pipes 76, 78 are disposed completely outside the combustion chamber 18, no portion of said pipe needs to run through the hot interior of the chamber of combustion. In addition, the horizontal stroke of the pipe 76, 78 is desirably supported by the mounting plate structure 52, so that neither the burner 68 nor the pilot / thermocouple assembly 70 exerts a cantilevered load on the pipe. The combustion chamber 18 is generally sealed except in the combustion air consumption openings 60 in the bottom side wall structure 48 and the mounting plate structure 52 (or only in the bottom side wall structure 48 in the mode shown in Figure 3A). In this way, the openings 60 essentially define the only passage through which the combustion air 86 can enter the interior of the combustion chamber 18. According to another key aspect of the present invention, the separation and configurations of the openings 60 are selected to cause the openings 60 (1) to allow the combustion air 86 to flow up through the openings 60 with a pressure drop, which is sufficiently low in order not to materially impede a combustion process. normal water heated with 10 fuel, while at the same time, (2) act as the retention passage of the flames preventing a downward flow of the flames through the openings 60 in the event that the flammable vapors passing up through the openings 60 are ignited inside the chamber combustion 18. To provide the combustion air inlet openings 60 with these two characteristics, their hydraulic or effective diameters and their passage lengths are selected so that the inflow of air upward through the openings 60 can occur with a minimum pressure drop, but the openings 60 act to reduce the rate of flame propagation downward in a manner that sufficient heat is drawn from the downwardly directed flames to extinguish them before they exit downwardly from the openings 60. this way, the outward flow of the descending flame through the bottom ends of the openings 60, caused by the ignition within the combustion chamber 18 of the flammable vapors entering upwardly of the combustion chamber through the openings 60, is prevented to thereby reduce the possibility that said ignition is extended to the flammable vapors externally. adjacent to the combustion chamber 18. There are two main flame control situations, which must be considered in the context of the design of water heaters. The first one refers to the high speed flame (ie, a flame that has a velocity of propagation greater than approximately 15.24 meters per second (50 feet per second)). To prevent a high-speed flame, the flame must be both decelerated and extinguished. The second situation refers to the low velocity flame (ie, a flame that has a velocity of propagation less than approximately 15.24 meters per second (50 feet per second)), in which case the extinguishing of the flame is usually sufficient to stop the flame. Whether the flame is extinguished or not, before it leaves a passage through which it travels, depends on several factors such as the length of the passage, the effective or hydraulic diameter of the passage, the speed of approach of the flame, and the differential pressure between the entrance and exit of the passage, the temperature of the material where the passage is formed. In turn, the approach speed of flame for a given fuel depends on the ratio of fuel and air mixture. The maximum velocity of the flame occurs in a stoichiometric fuel / air ratio, while the minimum velocity tends to occur in a weak fuel / air ratio. In general, as the flame velocity increases, the hydraulic diameter must be reduced and the length of the passage increased. In the illustrated preferred embodiment of the present invention, the four stacked metal plates 58 in the combustion chamber bottom side wall structure 48 (and the four stacked metal plates 66 in the mounting plate structure 52 shown in FIG. Figure 3) each has a thickness of approximately 0.16002 cm (0.063 inches). Accordingly, the total thickness of each of the bottom side wall structure 48 and the mounting plate structure is approximately 0.635 cm (0.25 inches). In this way, if each of these two structures is formed from a single layer of metal (preferably steel), the individual metal layer could similarly have a thickness of about 0.635 cm (0.25 inches). Preferably, the diameter of each of the openings 60 is approximately 0.16002 cm (0.063 inches), and the center-to-center clearance of the openings 60 is approximately 0.3175 cm (0.125 inches). As previously mentioned, the openings 60 have circular cross sections but can be provided with non-circular cross sections, having equivalent hydraulic diameters, if desired. In developing the water heater 10 of the present invention, it has been found that the use of specially configured combustion air inlet openings 60 in the bottom side of the combustion chamber 18 serves to extinguish low velocity flames, and extinguishing and decelerating high velocity flames, in a manner that prevents their downward flow through the openings 60. Since these flame counter-flow stop openings have been illustratively shown as being arranged along the bottom of the chamber of combustion 18, will be appreciated by those skilled in the art that they may be located anywhere on the water heater, and are effective for their intended purpose, so long as they essentially define the Lndi L lual passage. .- the combustion between the. • combustion chamber. The above detailed injury is clearly understood as it is given by way of illustration and example., PL spirit and scope of the present invention being limited only by the appended claims.

Claims (1)

1. CLAIMS i. A water heater characterized in that it comprises: a tank adapted to maintain a quantity of water; a combustion chamber arranged behind the tank and having a structure of the bottom side wall with a burner mounting opening extending upward therethrough; a mounting plate structure secured to the bottom side wall structure, over the burner mounting opening, and being removable therefrom; a fuel burner secured to the mounting plate structure, to be removed with the same side wall structure at the bottom, and projecting upwards into the combustion chamber; . a fuel supply line arranged externally to the combustion chamber and operatively connected to the fuel burner; and an air intake path through which the combustion air can move toward the bust chamber. . '.. KL water heater in accordance c < The I . • Lv üid Le • i .., n L, characterized poi.rio L c.iLentador d < • Water ••:; a calt'iii idm le agua > > Come on > > No gas 3. The water heater according to claim 1, characterized in that: said water heater further comprises a fuel valve device, and the fuel supply line is removably coupled to the thermostatic fuel valve and prevents the removal of the structure of mounting plate of the bottom side wall structure until the fuel supply line is decoupled from the fuel valve device. The water heater according to claim 3, characterized in that the fuel valve device is a thermostatic fuel valve. The water heater according to claim 1, characterized in that the air intake path includes a separate series of openings formed in the bottom side wall structure. The water heater according to claim 5, characterized in that the pull inlet path further includes a separate series of openings formed in the mounting plate structure. /. The water heater according to claim 1, characterized in that the path of ent ada. > air has an operating portion for (I) freely allowing the inflow of combustion air in a first direction into the combustion chamber and (II) preventing the outward flow of the flame from the combustion chamber through the combustion chamber. of the air path inlet portion in a second opposite direction in the first direction. The water heater according to claim 7, characterized in that the air inlet path portion includes a separate series of openings formed in the bottom side wall structure. 9. The water heater according to claim 8, characterized in that the air entry path portion further includes a separate series of openings formed in the mounting plate structure. THE. The water heater according to claim 8, characterized in that the separate series of openings formed in the bottom side wall structure have characteristics of predetermined hydraulic diameter? [Ue to make an extinguish a 1. Lama passing downwards to ravés from the same. LL. The water heater is in accordance with the claim, characterized by the fact that the structure of the water tank or bottom has an area of approximately 0. 635 cm (0.25 inches), and each of the separate series of normed openings in the bottom side wall structure has a generally circular cross section with a diameter ie around 0.16002 cm (0.063 inches). The water heater according to claim 11, characterized in that the separate series of openings formed in the bottom side wall structure has a center-to-center separation of about 0.3175 cm (0.125 inches). 13. The water heater according to claim 8, characterized in that the bottom side wall structure is formed from a stacked plurality of perforated metal plates, whose perforations are in register with each other and define in combination separate series of openings formed in the bottom side wall structure. The water heater according to claim 9, characterized in that the separate series of openings formed in the bottom wall side structure and the mounting plate structure have predetermined hydraulic diameter characteristics making >;? extinguish a flame that passes down through them. L5 The water heater in accordance with the L4 reivlndicacliin, raised character because the bottom side wall structure and the mounting plate structure, each having a thickness of approximately 0.635 cm (0.25 inches), and each of the openings formed in the bottom wall structure and the mounting plate structure has a generally circular cross section with a diameter of about 0.16002 cm (0.063 inches). The water heater according to claim 15, characterized in that the separate series of openings formed in the bottom wall side structure and the mounting plate structure have a center-to-center gap of approximately 0.3175 cm (0.125). inches). The water heater according to claim 9, characterized in that the bottom side wall structure 5 and the mounting plate structure are formed from a stacked plurality of perforated metal plates, whose perforations are in register between yes and define in combination said separate series of openings formed in the bottom side wall structure and the mounting plate structure. 18. The water heater according to claim 8, characterized in that the combustion bed L a is sealed except for the separate series of openings formed in the wall structure later L > r? Londo. . 19. The water heater according to claim 9, characterized in that the combustion chamber is sealed except for the separate series of openings formed in the side wall structure of fcndo and the mounting plate structure. 20. A water heater characterized in that it comprises: a tank adapted to maintain a quantity of water; a combustion chamber arranged behind the tank and having a bottom side wall structure with a burner mounting opening extending upwardly therethrough; a separate series of combustion air inlet openings formed in the bottom side wall structure; a hollow skirt structure extending downwardly beyond the bottom side wall structure and having a vertical side wall portion with a separate series of inlet openings formed therein to allow the flow of combustion air through the same towards < d. the interior of the hollow skirt structure for supplying from there to the combustion chamber through the separate shafts ^ combustion air inlet openings in the bottom side wall structure; a mounting plate structure removably secured to the bottom side wall structure above the burner mounting opening; a fuel burner secured to the mounting plate structure, for the removal therefrom of the bottom side wall structure, and projecting upwards into the combustion chamber; and a fuel supply line disposed outside the combustion chamber and operatively connected to the fuel burner. 21. The water heater according to claim 20, characterized in that the water heater is a gas-fired water heater. 22. The water heater according to claim 20, characterized in that it further comprises: an insulating jacket structure circumscribing the tank, said insulation jacket structure having an outer wall portion with an inner end section circumscribing the outside skirt structure and defines with it a full air inlet, the lower end section of the outer wall portion having a separate series of air inlet openings therein [that allow the combustion air to flow towards inward towards the plenum of air to supply from there to the interior of the hollow skirt structure through the inlet openings in its lateral wall portion. 23. The water heater according to claim 22, characterized in that: the vertical side wall portion of the hollow skirt structure and the outer wall portion of the insulation jacket structure generally have 0 access openings aligned in the same, the water heater further comprises a fuel valve device carried externally to the side wall portion of the insulating jacket structure, The fuel supply line extends outwardly through the openings of access and is removably coupled to the fuel valve device; and The mounting plate structure, the fuel burner, and a portion of the fuel supply pipe are removable outwardly through the access openings when the fuel supply pipe is uncoupled from the valve. fuel and the mounting plate structure is removed from the lat wall "") "> r il background of the combustion chamber. 24. The water heater according to claim 20, characterized in that the separate series of combustion air inlet openings formed in the bottom side wall structure are dimensioned and configured to (I) freely allow the upward combustion air to flow through the combustion chamber, and (II) prevent flames from flowing outwardly downward through the combustion chamber. 25. The water heater according to claim 24, characterized in that the separate series of openings formed in the bottom side wall structure have predetermined hydraulic diameter characteristics which cause a flame to pass through which the flame passes downwards. same. The water heater according to claim 25, characterized in that the bottom side wall structure has a thickness of approximately 0.635 cm (0.25 inches), and each of the separate series of openings formed in the side wall structure bottom has a generally circular cross section with a diameter of approximately 0.16002 cm (0.063 inches). 27. The contour water heater with claim 26, characterized in that the separate series of openings formed in the bottom side wall structure has a center-to-center gap of approximately 0.3175 cm 0.125 inches). The igua heater according to claim 25, characterized in that the bottom side wall structure is formed from a stacked plurality of perforated metal plates, whose perforations are in register with each other and define in combination separate series of openings formed in the bottom side wall structure. 29. A water heater characterized in that it comprises: a tank adapted to maintain a quantity of water; a combustion chamber disposed below the tank and having a bottom sidewall structure; a fuel burner extending upwards through the bottom side wall structure towards the combustion chamber; an externally arranged fuel supply line of the combustion chamber and operatively connected to the fuel burner; and a separate series of openings formed in the bottom side wall structure and circumscribing the burner > L 'fuel, d¡. is ubortu rs •• stando Lined and configured to (L) freely allow the flow of combustion air upward into the combustion chamber, and (II) prevent the external fl ow of the flames from the combustion chamber down through of the openings. 30. The water heater according to claim 29, characterized in that the fuel burner is removed downwards from the combustion chamber. The water heater according to claim 29, characterized in that the water heater is a gas-fired water heater. 32. The water heater according to claim 29, characterized in that the separate series of openings formed in the bottom side wall structure have predetermined hydraulic diameter characteristics which cause a flame to pass through which the flame passes downwards. same. 33. The water heater according to claim 32, characterized in that the bottom side wall structure has a thickness of approximately 0.635 cm. (0.25 inches), and each of the separate series of openings formed in the bottom sidewall structure has a generally circular cross section with a diameter of approximately 0.16002 cm (0.0o j inches). 34. The water heater according to claim 33, characterized in that the separate series of openings formed in the bottom side wall structure has a center-to-center separation of about 0.3175 cm (0.125 inches). 35. The water heater according to claim 29, characterized in that the bottom side wall structure is formed from a stacked plurality of perforated metal plates, whose perforations are in register with each other and define in combination separate series of openings formed in the bottom side wall structure. SUMMARY A fuel-fired water heater having a "combustion chamber disposed below the storage tank portion of an astia heater." The bottom side wall of the combustion chamber is defined by a perforated annular wall structure. with a perforated mounting wall structure being removably secured to the underside of the wall structure above the central opening therein A burner and associated pilot / thermocouple assembly are secured to the upper side of the mounting plate and they project upwards into the combustion chamber, with the pipe and the burner cabling and the pilot / thermocouple assembly extending externally below the combustion chamber, outwardly through a side wall access passage, and then returning upward along the outside of the water heater to heat to a thermostatic fuel valve To remove the burner mounted on the bottom plate and the pilot / thermocouple assembly, the fuel supply pipe must first be uncoupled from the thermostatic valve, thus ensuring that the access plate can not be removed while the burner Its on. The combustion chamber is essentially sealed to prevent the flow of combustion air thereto except through the perforations in its bottom side wall structure. These perforations are configured and sized to allow the flow of combustion air upwards into the combustion chamber with a minimum pressure drop, while also acting as a flame arrester to prevent the downward flow of the flames potentially caused by the entrance of the combustion chamber. Upflow of flammable vapors and their subsequent ignition inside the combustion chamber.