US20210341177A1

US20210341177A1 - Gas burner assembly

Info

Publication number: US20210341177A1
Application number: US16/863,888
Authority: US
Inventors: Jimmy Charles Smelcer; Mark Allan Murphy; Trent Conor Snively; Billy Anthony Batey
Original assignee: AO Smith Corp
Current assignee: AO Smith Corp
Priority date: 2020-04-30
Filing date: 2020-04-30
Publication date: 2021-11-04
Also published as: EP3904765A2; CA3116151A1; EP3904765A3

Abstract

An atmospheric gas water heater includes a burner assembly. The burner assembly includes a burner having a body, and a screen member coupled to the body. A conduit is fluidly connected to the body. The conduit has an open end configured to receive gas and air. The flow of gas and air from the open end through the conduit to the body and past the screen member is defined as a downstream direction. The screen member defines a zone of combustion. The gas and the air is 100% premixed together upstream of the zone of combustion. The body of the burner has a first segment extending between a first end and a second end, and second and third segments extending from the first segment. The second segment and the third segment extend parallel to and spaced apart from each other to form a U-shape.

Description

BACKGROUND

The present invention relates to a gas burning atmospheric water heater, and more specifically a gas burner assembly of a gas burning atmospheric water heater.

SUMMARY

In one embodiment, the disclosure provides an atmospheric gas water heater including a tank containing water to be heated, a flue assembly positioned within the tank, and a burner assembly in fluid communication with the flue assembly. The burner assembly includes a burner having a body, and a screen member coupled to the body. A conduit is fluidly connected to the body. The conduit has an open end. The open end is configured to receive gas and air. A flow of the gas and the air from the open end through the conduit to the body and past the screen member is defined as a downstream direction. The screen member defines a zone of combustion. The gas and the air is 100% premixed together upstream of the zone of combustion. The body of the burner has a first segment extending between a first end and a second end, a second segment extending from the first segment at the first end, and a third segment extending from the first segment at the second end. The second segment and the third segment extend parallel to and spaced apart from each other to form a U-shape.
In another embodiment, the disclosure provides an atmospheric gas water heater including a tank containing water to be heated, a flue assembly positioned within the tank, and a burner assembly in fluid communication with the flue assembly. The burner assembly includes a burner having a body, and a screen member coupled to the body. The body has a curved surface. A conduit is fluidly connected to the body. The conduit has an open end. The open end is configured to receive gas and air. A flow of the gas and the air from the open end through the conduit to the body and past the screen member is defined as a downstream direction. The screen member defines a zone of combustion. The gas and the air is 100% premixed together upstream of the zone of combustion. During operation, the burner is configured to oscillate at a first vibration frequency. During operation, flames produced at the zone of combustion are configured to oscillate at a second vibration frequency. The curved surface of the body is configured to maintain the first vibration frequency at a frequency greater than the second vibration frequency throughout operation of the water heater.
In yet another embodiment, the disclosure provides an atmospheric gas water heater including a tank containing water to be heated, a flue assembly positioned within the tank, and a combustion chamber fluidly connected to the flue assembly. A pilot assembly is at least partially positioned within the combustion chamber. A burner assembly is positioned within the combustion chamber. The burner assembly includes a burner having a body, and a screen member coupled to the body. A conduit is fluidly connected to the body. The conduit has an open end. The open end is configured to receive gas and air. A flow of the gas and the air from the open end through the conduit to the body and past the screen member is defined as a downstream direction. The screen member defines a zone of combustion. The gas and the air is 100% premixed together upstream of the zone of combustion. The pilot assembly is mounted outside of the combustion chamber.
Other independent aspects of the disclosure will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a water heater according to one construction.

FIG. 2 is a perspective view of the water heater of FIG. 1 with portions removed, illustrating a flue assembly and a burner assembly positioned within a combustion chamber of the water heater.

FIG. 3 is bottom perspective view of a portion of the water heater of FIG. 1, illustrating the combustion chamber of FIG. 2.

FIG. 4 is a perspective view of the burner assembly of FIG. 2.

FIG. 5 is a front perspective view of the burner assembly coupled to a door assembly of the combustion chamber of FIG. 3.

FIG. 6 is a rear perspective view of the burner assembly and the door assembly of FIG. 5.

FIG. 7 is a perspective view of a portion of the burner assembly of FIG. 2.

FIG. 8 is a partial view of a portion of a burner of the burner assembly of FIG. 7, illustrating a baffle assembly of the burner assembly.

FIG. 9 is an end view of the baffle assembly of FIG. 8.

FIG. 10 is a partial side view of a portion of the burner and the baffle assembly of FIG. 8.

Before any independent embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure is capable of other independent embodiments and of being practiced or of being carried out in various ways.

DETAILED DESCRIPTION

Use of “including” and “comprising” and variations thereof as used herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Use of “consisting of” and variations thereof as used herein is meant to encompass only the items listed thereafter and equivalents thereof.
Relative terminology, such as, for example, “about”, “approximately”, “substantially”, etc., used in connection with a quantity or condition would be understood by those of ordinary skill to be inclusive of the stated value and has the meaning dictated by the context (for example, the term includes at least the degree of error associated with the measurement of, tolerances (e.g., manufacturing, assembly, use, etc.) associated with the particular value, etc.). Such terminology should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression “from about 2 to about 4” also discloses the range “from 2 to 4.” The relative terminology may refer to plus or minus a percentage (e.g., 1%, 5%, 10% or more) of an indicated value.
Also, the functionality described herein as being performed by one component may be performed by multiple components in a distributed manner. Likewise, functionality performed by multiple components may be consolidated and performed by a single component. Similarly, a component described as performing particular functionality may also perform additional functionality not described herein. For example, a device or structure that is “configured” in a certain way is configured in at least that way but may also be configured in ways that are not listed.
With reference to FIGS. 1 and 2, a fuel-fired atmospheric water heater 10 is illustrated with portions removed for illustrative purposes. The water heater 10 includes a tank 18 defining an interior space 22 (FIG. 2) for holding water, a flue assembly 26 extending through the tank 18, and a burner assembly 30 in fluid communication with the flue assembly 26.
The tank 18 has a first, bottom end 34 (FIG. 2) and a second, top end 38 opposite the bottom end 34 (FIG. 2). The tank 18 defines a longitudinal axis 42 extending through the bottom end 34 and the top end 38. The tank 18 supports an inlet spud 46 and an outlet spud 50. In the illustrated embodiment, the inlet spud 46 and the outlet spud 50 are positioned at and supported by the top end 38 of the tank 18. Further, the tank 18 is supported on a skirt 54 coupled to the bottom end 34.
A cold water supply pipe 58 communicates between a source of cold water (not shown) and the inlet spud 46. A dip tube 62 extends from the inlet spud 46 at the top end 38 into the tank 18 toward the bottom end 34. Additionally, a hot water pipe 66 communicates between a hot water access point or point-of-use (not shown) and the outlet spud 50. The water heater 10 may further include an anode assembly (not shown) positioned within the tank 18. The anode assembly may be supported by and extend from the top end 38 into the tank 18.
The hot water access point or point-of-use may be, for example, a faucet or a water-consuming appliance. Cold water is supplied at supply pressure (usually around 30 psi but sometimes as high as 60 psi) from the cold water source (e.g., a water utility or well pump) through the cold water supply pipe 58. When the access point is opened, the hot water pipe 66 is exposed to atmospheric pressure, which permits cold water to flow at supply pressure into a lower portion 70 of the tank 18 via the dip tube 62 and displace hot water from an upper portion 74 of the tank 18 via the outlet spud 50 and hot water pipe 66.
With reference to FIGS. 2 and 3, a combustion chamber 78 is positioned axially underneath the tank 18 relative to the longitudinal axis 42. In particular, the combustion chamber 78 is defined by a wall member 82, an intermediate member 86, and a bottom 90 spaced from the intermediate member 86 relative to the longitudinal axis 42. The wall member 82 is fixedly coupled to the tank 18. In the illustrated embodiment, although not shown, the skirt 54 surrounds the wall member 82. In other embodiments, the skirt 54 may itself define the combustion chamber 78.
The intermediate member 86 separates the combustion chamber 78 from the tank 18. The intermediate member 86 forms the bottom end 34 of the tank 18. Further, the bottom 90 of combustion chamber 78 is supported on a floor or other surface of a building (e.g., house, etc.). The illustrated bottom 90 is formed by solid material, and includes a ¼ inch foil-faced layer of insulation.
With reference to FIG. 3, the illustrated combustion chamber 78 further includes a door assembly 94 which forms a portion of the wall member 82. The door assembly 94 includes a door 98 movably coupled to a fixed portion of the wall member 82. Specifically, an inner surface 102 (FIG. 6) of the door 98 defines a portion of the combustion chamber 78. The door assembly 94 is configured to provide access by a user to the combustion chamber 78.
Referring back to FIG. 2, the flue assembly 26 extends through the tank 18 from the combustion chamber 78 to an exhaust vent 106 positioned at the top end 38 of the tank 18. In particular, the flue assembly 26 is fluidly connected to the combustion chamber 78 through an opening in the intermediate member 86. The water heater 10 is an atmospheric water heater that does not include any powered blowers or fans to create airflow, but rather relies upon the natural convection of air and combustion exhaust through the water heater 10.
With continued reference to FIG. 2, the flue assembly 26 includes a flue 110. The flue 110 is fluidly connected to the combustion chamber 78 at a first end of the flue 110, and the exhaust vent 106 at a second end opposite the first end. In the illustrated embodiment, the flue assembly 26 includes one flue 110 extending through a center of the tank 18. The flue assembly 26 is configured to receive flue gases produced by the burner assembly 30 and direct the flue gases through the one or more flues 110 to the exhaust vent 106 for heating the water in the tank 18. With particular reference to FIG. 2, the flue 110 includes a flue baffle 114 to improve heat transfer from the flue to the water within the tank 18.
Condensation produced within the flue assembly 26 during operation of the water heater 10 is directed (i.e., by gravity) along inner walls of the flue 110 toward the combustion chamber 78. As such, the condensation is configured to be received in the combustion chamber 78 from the flue assembly 26. A drain line (not shown) may be fluidly connected to the bottom 90 of the combustion chamber 78 for withdrawing the condensation from the system.
With reference to FIGS. 2 and 4, the burner assembly 30 is positioned within the combustion chamber 78. The burner assembly 30 and combustion chamber 78, when used together, may also be collectively referred to as a combustion system. The burner assembly 30 includes a burner 120, a screen member 124, and a conduit 128 (FIG. 4). The burner assembly 30 is supported in cantilever fashion by the door 98 of the combustion chamber 78.
With reference to FIGS. 7 and 8, the burner 120 includes a body 132 having a plurality of surfaces 134, 138. In the illustrated embodiment, the body 132 has an outer surface 134 and an inner surface 138. In particular, each of the outer and inner surfaces 134, 138, respectively, is formed by a curved surface. In the illustrated embodiment, a cross-sectional shape of the body is a C-shape to form the curved surfaces. As such, a shape of the body 132 may be referred to as being semi-round. The outer surface 134 is convex and the inner surface 138 is concave. The specific shape of the burner body 132 may inhibit burner resonance, as further discussed below.
The body 132 includes a plurality of segments 142A-142C. In the illustrated embodiment, the body 132 includes a first segment 142A, and second and third segments 142B, 142C, respectively, extending therefrom. Specifically, the first segment 142A includes a first end 146 and a second end 150. The first segment 142A has a length A (FIG. 4) measured between the first end 146 and the second end 150. First and second side edges 154A, 154B extend between the first and second ends 146, 150 of the first segment 142A. The second segment 142B extends from the first end 146 parallel to the conduit 128, and the third segment 142C extends from the second end 150 parallel to the conduit 128. Additionally, the second and third segments 142B, 142C extend parallel to and spaced apart from each other such that the body 132 has a U-shape. In other words, the burner body 132 has a shape that may be termed as a horseshoe shape. The first, second, and third segments 142A-142C define a conduit-receiving space 158 located therebetween. The conduit 128 is in the conduit-receiving space 158 between the first and second segments 142B, 142C. Further, each of the first, second, and third segments 142A-142C includes the curved surfaces 134, 138.
With reference to FIG. 2, the burner assembly 30 is positioned at a predetermined location within the combustion chamber 78. In the illustrated embodiment, the burner assembly 30 is positioned at the predetermined location such that the first, second, and third segments 142A-142C are not located directly underneath the opening of the intermediate member 86. Instead, the conduit-receiving space 158 is positioned directly underneath the flue 110. This may reduce or eliminate the occurrence of condensation falling from the flue assembly 26 directly onto the burner 120. As such, the burner 120 is shaped and positioned at the predetermined location to avoid contact with the condensation from the flue assembly 26. In particular, flue gas condensate is known to be acidic, with pH values in the range of 2.5-3.5. A burner life may be increased by inhibiting or preventing contact between the flue gas condensate and the exposed surfaces of the burner 120. As such, the U-shape of the burner 120 may inhibit collection of condensation on the burner 120 (i.e., screen member 124), and/or reduce corrosion of the burner 120 or screen member 124 due to condensation.
Each of the segments 142A-142C includes a plurality of edges 162 (FIG. 7) that form a top 164 of the body 132. The screen member 124 is movably coupled to the top 164 of the body 132. The screen member 124 includes a first side 166 and a second, opposite side (not shown). The first side 166 is in facing relationship with the combustion chamber 78. The second side is in facing relationship with the inner, curved surface 138 of the body 132. As shown in FIG. 7, the screen member 124 is also curved or rounded such that the first side 166 is convex (i.e., bends away from the inner surface 138 of the body 132). The second side of the screen member 124 compliments the curve of the first side 166. The screen member 124 is formed by a mesh material. Further, the illustrated screen member 124 comprises of a high temperature-resistant material such as metal (e.g., stainless steel Incoloy 601 metal). The screen member 124 defines a zone of combustion 168 of the burner assembly 30.
The screen member 124 is selectively movable relative to the top 164 of the body 132. In particular, the top 164 of the burner body 132 includes a flange 170 (only a top side of which is shown in FIG. 7) extending around all of the plurality of edges 162 of the body 132. The flange 170 is configured to bend or fold over outer edges of the screen member 124 such that the edges of the screen member are positioned between the flange 170. As such, the screen member 124 is movably retained to the body 132 of the burner 120. Accordingly, the screen member 124 is configured to float relative to the body 132. This may relieve thermal stresses that occur within the screen member 124 as the burner 120 is operated.
The body 132 and the screen member 124 cooperate to define an internal chamber 174 (FIG. 8) of the burner assembly 30. The conduit 128 extends from the body 132 and is fluidly connected to the internal chamber 174. As noted above, the conduit 128 is positioned in the conduit-receiving space 158 between the second and third segments 142B, 142C, respectively. Further, the conduit 128 extends parallel to and spaced from the second and third segments 142B, 142C, respectively. As such, the conduit 128 extends through the conduit-receiving space 158. In the illustrated embodiment, the conduit 128 is positioned at a center position along the length A of the first segment 142A. In other embodiments, the conduit 128 may be positioned at other axial positions along the length A of the first segment 142A.
With reference to FIG. 7, the conduit 128 includes a first end 178 and a second end 182 opposite the first end 178. The conduit 128 further includes a passage 186 extending between the first end 178 and the second end 182. In the illustrated embodiment, the second side edge 154B of the first segment 142A defines an opening 190 (FIG. 8), and the passage 186 is aligned with the opening 190 at the second end 182 of the conduit 128. Accordingly, the passage 186 of the conduit 128 is in fluid communication with the internal chamber 174 of the body 132/screen member 124. The first end 178 of the conduit 128 extends farther than each respective end of the second and third segments 142B, 142C (i.e., it extends out of the conduit-receiving space 158).
With particular reference to FIGS. 5 and 6, the conduit 128 extends from the burner body 132 through the wall member 82 of the combustion chamber 78. In the illustrated embodiment, the conduit 128 extends through the door 98 of the door assembly 94. In other embodiments, the conduit 128 may extend through the wall member 82 at any other location of the combustion chamber 78. Accordingly, the first end 178 of the conduit 128 is positioned outside of the combustion chamber 78. Specifically, in the illustrated embodiment, a portion of the conduit 128 is coupled by a plate member 194 and fasteners 198 to the inner surface 102 of the door 98 (FIG. 5). The plate member 194 is located closer to the first end 178 of the conduit 128 than the second end 182. The burner 120 is supported in cantilever fashion in the combustion chamber 78 by the conduit 128 which is rigidly mounted to the door 98.
With reference to FIGS. 3 and 4, an air guide member 202 is coupled to the first end 178 of the conduit 128, outside of the combustion chamber 78 and, in this regard is an extension of the conduit 128. In the illustrated embodiment, the air guide member 202 is a venturi tube having a passage aligned with the passage 186 of the conduit 128. The air guide member 202 forms a venturi portion 206 of the conduit 128. In the illustrated embodiment, the venturi portion 206 is formed as a separate piece and coupled (e.g., by welding, etc.) to the first end 178 of the conduit 128. In this embodiment, the first end 178 of the conduit 128 receives a portion of the air guide member 202. In other embodiments, the venturi portion 206 may be formed as an integral portion of the conduit 128 by shaping the first end 178 of the conduit 128 in the shape of a venturi. The venturi portion 206 draws air into the conduit 128 in response to a flow of pressurized gas flowing through the venturi portion 206.
The water heater 10 includes a gas supply assembly 220 (FIG. 3). The gas supply assembly 220 includes a valve 224 and a gas pipe 228 fluidly connected to the valve 224. In the illustrated embodiment, the valve 224 is supported by an outer surface of the tank 18, and the gas pipe 228 extends from the valve 224 toward the venturi portion 206. In some embodiments, the end of the gas pipe 228 may extend partially within the venturi portion 206. The gas valve 224 is configured to selectively supply gas to the venturi portion 206. In the illustrated embodiment, the gas valve 224 is configured to provide gas flow at a constant pressure between 3.5 inches water column and 4.0 inches water column. In some embodiments, the gas valve 224 is configured to provide gas flow at a constant pressure of 3.5 inches water column. In other embodiments, the gas valve 224 is configured to provide gas flow at a constant pressure between 3.5 inches water column and 5.0 inches water column. In particular, other water heater designs may require a constant gas pressure at 5.0 inches water column or higher. The illustrated water heater 10 is configured to be installed in locations where a supply of gas cannot be maintained above a constant pressure of 4.0 inches water column.
The gas supply assembly 220 is configured to selectively supply gas to the venturi portion 206 such that air is drawn from the surrounding atmosphere into the venturi portion 206 and into the conduit 128 (e.g., by aspiration) (FIG. 4). A downstream direction is defined as a direction of the flow of gas and air into the conduit 128 via the venturi portion 206 to the internal chamber 174 of the body 132/screen member 124. The air mixing with the gas upstream of the zone of combustion 168 (i.e., the screen member 124) may be termed as primary air.
With reference to FIGS. 8-10, the burner assembly 30 includes a baffle assembly 236 positioned within the internal chamber 174. In the illustrated embodiment, the baffle assembly 236 includes a plurality of baffle members 240, 244 having a base baffle member 240, and two curved baffle members 244 extending therefrom (FIG. 9). The base baffle member 240 extends from the first side edge 154A of the first segment 142A of the burner body 132 toward the second, opposite side edge 154B (FIG. 8). More specifically, the base baffle member 240 extends toward the opening 190. The base baffle member 240 is aligned with a center of the opening 190, and accordingly a center axis 248 of the conduit passage 186. An edge 252 (FIG. 10) of the base baffle member 240 conforms to the curved inner surface 138 of the body 132.
The curved baffle members 244 are coupled to the base baffle member 240. In the illustrated embodiment, each curved baffle member 244 is coupled to a respective side of the base baffle member 240. In one example, spot welding is used to couple the curved baffle members 244 to the base baffle member 240. In other embodiments, the base baffle member 240 and curved baffle members 244 may be formed by a single, integral piece. In particular, the curved baffle members 244 each form a gull wing shape such that the baffle assembly 236 may be termed as a gull wing baffle assembly. The baffle assembly 236 comprises of a metal material such as 20 or 22 gauge sheet aluminized steel. The baffle assembly 236 is configured to direct the primary air/gas mixture (mixed upstream of the zone of combustion 168) flowing from the conduit 128 within the internal chamber 174 of the burner assembly 30.
With reference to FIGS. 3, 5, and 6, the water heater 10 includes a pilot assembly 260. The illustrated pilot assembly 260 includes a pilot burner 264 and a spark ignitor 268. As such, the illustrated pilot assembly 260 may be referred to as a spark pilot. In other embodiments, the pilot assembly 260 may utilize a resistance heating element instead of the spark ignitor 268. The illustrated pilot assembly 260 further includes a thermocouple 272. The pilot assembly 260 is supported by the wall member 82 of the combustion chamber 78. In particular, the pilot assembly 260 is supported by the door 98 of the door assembly 94. The pilot burner 264, spark ignitor 268, and thermocouple 272 extend from the inner surface 102 of the door 98 toward the burner assembly 30 (i.e., the screen member 124) within the combustion chamber 78 (FIG. 6). An end of each of the pilot burner 264, spark ignitor 268, and thermocouple 272 is positioned proximate the burner assembly 30 (i.e., the second segment 142B). In other embodiments, the pilot assembly 260 may not include the thermocouple 272.
A pilot gas line 276 extends from the gas valve 224 to the pilot burner 264 (FIG. 3) for selectively supplying gas to the pilot burner 264. In the illustrated embodiment, the thermocouple 272 is positioned above the burner 120 relative to the longitudinal axis 42, and the spark ignitor 268 is positioned next to the thermocouple 272. Each of the pilot burner 264, spark ignitor 268, and thermocouple 272 extends from outside of combustion chamber 78 through the door 98. As such, the pilot burner 264, spark ignitor 268, and thermocouple 272 may be accessed by a user outside of the combustion chamber 78. In other embodiments, other components of the pilot assembly 260 may be positioned through the door 98 outside of the combustion chamber 78. This may facilitate cleaning, servicing, repair, and/or replacement of parts of the pilot assembly 260.
In operation, when there is a call for heat, the gas valve 224 is selectively opened to provide gas flow at a constant pressure. In the illustrated embodiment, the gas flow is at a constant pressure of 3.5 inches water column. The gas flow is then injected through an orifice of the gas valve 224 into the air guide member 202 such that the gas flows through the air guide member 202 and subsequently the conduit 128. Air is drawn into the gas flow stream by aspiration, and effectively mixes with the gas flow to form a desirable homogeneous air/gas mixture before the air/gas mixture reaches the screen member 124. In particular, the air that is being drawn into the air guide member 202 is the primary air. Accordingly, the primary air dilutes the gas flow prior to the gas flow reaching the zone of combustion 168.
The baffle assembly 236 directs the primary air/gas mixture entering the internal chamber 174 of the burner 120 from the conduit 128 to one side or the other of the base baffle member 240. In particular, the curved baffle members 244 separate the primary air/gas mixture into two paths, each path directed through one of the second and third segments 142B, 142C, respectively, of the burner 120. Accordingly, the baffle assembly 236 may facilitate the distribution and flow of the primary air/gas mixture through the internal chamber 174. More specifically, the baffle assembly 236 may facilitate maintaining an even balance of pressure underneath the screen member 124 (i.e., zone of combustion 168), thereby reducing and/or preventing overheating in localized areas of the screen member 124. Once the air/gas mixture flows past the screen member 124 in the downstream direction (e.g., the air/gas mixture enters the combustion chamber 78 via the screen member 124) proximate the lighted pilot burner 264, the air/gas mixture is ignited by the pilot burner 264.
The burner assembly 30 is configured such that the gas and the air are 100% premixed together upstream of the zone of combustion 168 (i.e., the screen member 124). In particular, all of the air entering and flowing through the combustion system 30, 78 is introduced through the venturi portion 206. The gas is entrained within the air resulting in a gas/air mixture ready for combustion at the screen member 124 of the burner assembly 30. In particular, the valve 224, the conduit 128 including the venturi portion 206, and/or the screen member 124 is configured such that the gas and air is 100% premixed together. This may be achieved based on one or more of the following: a predetermined flow rate of gas controlled by the valve 224, an airflow rate of air controlled by the venturi portion 206, a size (e.g., length, diameter, etc.) of the conduit 128, and/or a velocity of the air/gas mixture exiting the burner 120 (i.e., past the screen member 124). For example, the screen member 124 is configured as a backpressure device to limit the exit velocity of the air/gas mixture through the screen member 124. More specifically, the screen member 124 includes a plurality of holes or perforations which define the amount of open surface area relative to a total surface area of the screen member 124. The open area (i.e., perforations or holes in the screen member 124) relative to the total surface area of the screen member 124 determines the exit velocity of the air/gas mixture. As such, the amount of open area relative to the total surface area of the screen member 124 is selected to achieve a predetermined exit velocity of the air/gas mixture. In the illustrated embodiment, the open area relative to the total surface area of the screen member 124 is between 25% and 30%. In some embodiments, the open area relative to the total surface area of the screen member 124 is between 15% and 40%. The screen member 124 is further configured to evenly distribute the air/gas mixture at any point located on the zone of combustion 168. Accordingly, the air/gas mixture may be uniformly distributed on the zone of combustion 168 such that an even loading on the screen member 124 and/or an even balance of pressure underneath the screen member 124 (i.e., zone of combustion 168) is achieved, thereby reducing and/or preventing overheating in localized areas of the screen member 124. The control of the exit velocity may also inhibit or prevent flashback.
Additionally, the exit velocity controlled by the screen member 124 permits combustion to occur immediately downstream of the screen member 124 relative to the downstream direction such that the heat from the combustion flame is absorbed by the screen member 124, thereby limiting a flame temperature of the combustion flame to below a predetermined temperature at which nitrogen oxide forms. As such, nitrogen oxide emissions from the combustion flame remain below a predetermined maximum level that can be produced for a natural gas-fired water heater.
Further, since all gas entering the combustion system 30, 78 is combusted at the zone of combustion 168 (i.e., the screen member 124), no secondary air is necessary to dilute any gas remaining downstream of the screen member 124. In addition, the pilot assembly 260 is fed by natural convection of air flow through the burner assembly 30. Thus, no additional openings in the bottom 90 or combustion chamber door 98 are required to provide the pilot assembly 260 with combustion air. Accordingly, a flammable vapor screen does not need to be provided at the bottom 90 of the combustion chamber 78. In other words, there are no other openings in the bottom 90 of the combustion chamber 78 for providing secondary air into the combustion chamber 78 that need to be covered by a flammable vapor screen. With only one opening in the combustion chamber 78 (i.e., the open first end 178 of the conduit 128) to ingest flammable vapors, the water heater 10 may be configured to minimize the amount of flammable vapors entering the combustion chamber 78.
During operation of the water heater, the burner body 132 has a first, natural vibration frequency, and flames produced by the burner assembly at the zone of combustion 168 oscillate at a second, predetermined vibration frequency. The first vibration frequency occurs due to pressure pulses within the combustion chamber 78. The second vibration frequency is based on the oscillation of flame speed pulsations (i.e., combustion rate fluctuations) that pass through the screen member 124. Burner resonance may occur when the first vibration frequency synchronizes with the second vibration frequency such that the pressure pulses are in phase with the fluctuations in the heat released from combustion. The curved or round shape of both the burner body 132 and the screen member 124 may increase a stiffness of the burner 120 to affect the first vibration frequency. In other words, the first vibration frequency is determined by the round-shape of the burner 120. A radius of the curvature of the body 132 is selected such that the first vibration frequency is substantially greater than the second vibration frequency. In some embodiments, the shape of the burner 120 is configured such that the first vibration frequency is between 1.25 and 1.75 times greater than the second vibration frequency. In some embodiments, the shape of the burner 120 is configured such that the first vibration frequency is 1.5 times greater than the second vibration frequency. In other embodiments, the first vibration frequency is greater than the second vibration frequency by 150 Hz or more. In yet other embodiments, the first vibration frequency is greater than the second vibration frequency by 300 Hz or more. In yet still other embodiments, the first vibration frequency is between 100 Hz and 350 HZ greater than the second vibration frequency. Accordingly, the shape of the burner 120 is configured such that the first vibration frequency is at a frequency where the surfaces of the burner body 132/screen member 124 are not in resonance with the second vibration frequency or any of its harmonics. Further, the round shape of the burner 120 is configured to maintain the first natural vibration frequency at a greater frequency than the second predetermined vibration frequency throughout operation of the burner 120. Accordingly, burner resonance is inhibited or completely eliminated during operation.
Accordingly, various embodiments of an atmospheric gas water heater 10 having a burner assembly 30 are described herein that is operable to use only primary air to dilute gases for combustion to heat the water within a tank 18. The burner assembly 30 further has a U-shape and is positioned within the combustion chamber 78 to avoid condensation produced in a flue assembly 26. Further, the burner 120 of the burner assembly 30 is shaped to reduce or inhibit burner resonance. The pilot assembly 260 is accessible by a user outside of the combustion chamber 78 to facilitate service and replacement of parts. Operation of the burner assembly 30 is reliable under a minimum gas supply of 3.5 inches water column.
Although the disclosure has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the disclosure as described. Various features and/or advantages of the disclosure are set forth in the following claims.

Claims

What is claimed is:

1. An atmospheric gas water heater comprising:

a tank containing water to be heated;

a flue assembly positioned within the tank; and

a burner assembly in fluid communication with the flue assembly, the burner assembly including,

a burner having a body, and a screen member coupled to the body, and

a conduit fluidly connected to the body, the conduit having an open end, the open end configured to receive gas and air,

wherein a flow of the gas and the air from the open end through the conduit to the body and past the screen member is defined as a downstream direction,

wherein the screen member defines a zone of combustion,

wherein the gas and the air is 100% premixed together upstream of the zone of combustion, and

wherein the body of the burner has a first segment extending between a first end and a second end, a second segment extending from the first segment at the first end, and a third segment extending from the first segment at the second end, the second segment and the third segment extending parallel to and spaced apart from each other to form a U-shape.

2. The atmospheric gas water heater of claim 1, wherein the gas is only diluted by the air entering the burner assembly via the conduit.

3. The atmospheric gas water heater of claim 1, further comprising a combustion chamber configured to receive the burner assembly, wherein all of the air entering the combustion chamber is directed through the body of the burner and past the screen member.

4. The atmospheric gas water heater of claim 1, wherein the conduit includes a venturi portion, and wherein the venturi portion is positioned at the open end.

5. The atmospheric gas water heater of claim 1, wherein the conduit is positioned between the second segment and the third segment, and wherein the conduit is fluidly connected to the first segment.

6. The atmospheric gas water heater of claim 1, wherein the burner assembly includes an internal chamber defined by the body and the screen member, wherein a baffle assembly is positioned within the internal chamber for directing the air and gas within the internal chamber, and wherein the baffle assembly is positioned within the first segment.

7. An atmospheric gas water heater comprising:

a tank containing water to be heated;

a flue assembly positioned within the tank; and

a burner having a body, and a screen member coupled to the body, the body having a curved surface, and

wherein the screen member defines a zone of combustion,

wherein the gas and the air is 100% premixed together upstream of the zone of combustion,

wherein during operation, the burner is configured to oscillate at a first vibration frequency,

wherein during operation, flames produced at the zone of combustion are configured to oscillate at a second vibration frequency, and

wherein the curved surface of the body is configured to maintain the first vibration frequency at a frequency greater than the second vibration frequency throughout operation of the water heater.

8. The atmospheric gas water heater of claim 7, wherein the gas is only diluted by the air entering the burner assembly via the conduit.

9. The atmospheric gas water heater of claim 7, further comprising a combustion chamber configured to receive the burner assembly, wherein all of the air entering the combustion chamber is directed through the body of the burner and past the screen member.

10. The atmospheric gas water heater of claim 7, wherein the conduit includes a venturi portion, and wherein the venturi portion is positioned at the open end.

11. The atmospheric gas water heater of claim 7, wherein the first vibration frequency is at least 1.5 times greater than the second vibration frequency.

12. The atmospheric gas water heater of claim 7, wherein a cross-sectional shape of the body is a C-shape to form the curved surface.

13. The atmospheric gas water heater of claim 7, wherein the body includes a flange, and wherein the screen member is movably coupled to the body by the flange.

14. An atmospheric gas water heater comprising:

a tank containing water to be heated;

a flue assembly positioned within the tank;

a combustion chamber fluidly connected to the flue assembly;

a pilot assembly at least partially positioned within the combustion chamber; and

a burner assembly positioned within the combustion chamber, the burner assembly including,

a burner having a body, and a screen member coupled to the body, and

wherein the screen member defines a zone of combustion,

wherein the pilot assembly is mounted outside of the combustion chamber.

15. The atmospheric gas water heater of claim 14, wherein the gas is only diluted by the air entering the burner assembly via the conduit.

16. The atmospheric gas water heater of claim 14, wherein all of the air entering the combustion chamber is directed through the body of the burner and past the screen member.

17. The atmospheric gas water heater of claim 14, wherein the conduit includes a venturi portion, and wherein the venturi portion is positioned at the open end.

18. The atmospheric gas water heater of claim 14, wherein the combustion chamber is defined at least partially by a wall member, the wall member having an outer surface and an inner surface, and wherein the pilot assembly is mounted to the outer surface and extends through the wall member from the outer surface through the inner surface and into the combustion chamber.

19. The atmospheric gas water heater of claim 18, wherein the combustion chamber includes a door assembly having a door movably mounted to a fixed portion of the wall member, the door forming a portion of the wall member, and wherein the pilot assembly is mounted to the door.

20. The atmospheric gas water heater of claim 14, wherein the pilot assembly includes a pilot burner, a spark ignitor, and a thermocouple.