US20210341177A1 - Gas burner assembly - Google Patents

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 ofFIG. 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 ofFIG. 1, illustrating the combustion chamber ofFIG. 2.
• FIG. 4 is a perspective view of the burner assembly ofFIG. 2.
• FIG. 5 is a front perspective view of the burner assembly coupled to a door assembly of the combustion chamber ofFIG. 3.
• FIG. 6 is a rear perspective view of the burner assembly and the door assembly ofFIG. 5.
• FIG. 7 is a perspective view of a portion of the burner assembly ofFIG. 2.
• FIG. 8 is a partial view of a portion of a burner of the burner assembly ofFIG. 7, illustrating a baffle assembly of the burner assembly.
• FIG. 9 is an end view of the baffle assembly ofFIG. 8.
• FIG. 10 is a partial side view of a portion of the burner and the baffle assembly ofFIG. 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 toFIGS. 1 and 2, a fuel-firedatmospheric water heater10 is illustrated with portions removed for illustrative purposes. Thewater heater10 includes atank18 defining an interior space22 (FIG. 2) for holding water, aflue assembly26 extending through thetank18, and aburner assembly30 in fluid communication with theflue assembly26.
• Thetank18 has a first, bottom end34 (FIG. 2) and a second,top end38 opposite the bottom end34 (FIG. 2). Thetank18 defines alongitudinal axis42 extending through thebottom end34 and thetop end38. Thetank18 supports an inlet spud46 and an outlet spud50. In the illustrated embodiment, the inlet spud46 and the outlet spud50 are positioned at and supported by thetop end38 of thetank18. Further, thetank18 is supported on askirt54 coupled to thebottom end34.
• A coldwater supply pipe58 communicates between a source of cold water (not shown) and the inlet spud46. Adip tube62 extends from the inlet spud46 at thetop end38 into thetank18 toward thebottom end34. Additionally, ahot water pipe66 communicates between a hot water access point or point-of-use (not shown) and the outlet spud50. Thewater heater10 may further include an anode assembly (not shown) positioned within thetank18. The anode assembly may be supported by and extend from thetop end38 into thetank18.
• 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 coldwater supply pipe58. When the access point is opened, thehot water pipe66 is exposed to atmospheric pressure, which permits cold water to flow at supply pressure into alower portion70 of thetank18 via thedip tube62 and displace hot water from anupper portion74 of thetank18 via the outlet spud50 andhot water pipe66.
• With reference toFIGS. 2 and 3, acombustion chamber78 is positioned axially underneath thetank18 relative to thelongitudinal axis42. In particular, thecombustion chamber78 is defined by awall member82, anintermediate member86, and a bottom90 spaced from theintermediate member86 relative to thelongitudinal axis42. Thewall member82 is fixedly coupled to thetank18. In the illustrated embodiment, although not shown, theskirt54 surrounds thewall member82. In other embodiments, theskirt54 may itself define thecombustion chamber78.
• Theintermediate member86 separates thecombustion chamber78 from thetank18. Theintermediate member86 forms thebottom end34 of thetank18. Further, the bottom90 ofcombustion chamber78 is supported on a floor or other surface of a building (e.g., house, etc.). The illustrated bottom90 is formed by solid material, and includes a ¼ inch foil-faced layer of insulation.
• With reference toFIG. 3, the illustratedcombustion chamber78 further includes adoor assembly94 which forms a portion of thewall member82. Thedoor assembly94 includes adoor98 movably coupled to a fixed portion of thewall member82. Specifically, an inner surface102 (FIG. 6) of thedoor98 defines a portion of thecombustion chamber78. Thedoor assembly94 is configured to provide access by a user to thecombustion chamber78.
• Referring back toFIG. 2, theflue assembly26 extends through thetank18 from thecombustion chamber78 to anexhaust vent106 positioned at thetop end38 of thetank18. In particular, theflue assembly26 is fluidly connected to thecombustion chamber78 through an opening in theintermediate member86. Thewater heater10 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 thewater heater10.
• With continued reference toFIG. 2, theflue assembly26 includes aflue110. Theflue110 is fluidly connected to thecombustion chamber78 at a first end of theflue110, and theexhaust vent106 at a second end opposite the first end. In the illustrated embodiment, theflue assembly26 includes oneflue110 extending through a center of thetank18. Theflue assembly26 is configured to receive flue gases produced by theburner assembly30 and direct the flue gases through the one ormore flues110 to theexhaust vent106 for heating the water in thetank18. With particular reference toFIG. 2, theflue110 includes aflue baffle114 to improve heat transfer from the flue to the water within thetank18.
• Condensation produced within theflue assembly26 during operation of thewater heater10 is directed (i.e., by gravity) along inner walls of theflue110 toward thecombustion chamber78. As such, the condensation is configured to be received in thecombustion chamber78 from theflue assembly26. A drain line (not shown) may be fluidly connected to the bottom90 of thecombustion chamber78 for withdrawing the condensation from the system.
• With reference toFIGS. 2 and 4, theburner assembly30 is positioned within thecombustion chamber78. Theburner assembly30 andcombustion chamber78, when used together, may also be collectively referred to as a combustion system. Theburner assembly30 includes aburner120, ascreen member124, and a conduit128 (FIG. 4). Theburner assembly30 is supported in cantilever fashion by thedoor98 of thecombustion chamber78.
• With reference toFIGS. 7 and 8, theburner120 includes abody132 having a plurality ofsurfaces134,138. In the illustrated embodiment, thebody132 has anouter surface134 and aninner surface138. In particular, each of the outer andinner surfaces134,138, 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 thebody132 may be referred to as being semi-round. Theouter surface134 is convex and theinner surface138 is concave. The specific shape of theburner body132 may inhibit burner resonance, as further discussed below.
• Thebody132 includes a plurality ofsegments142A-142C. In the illustrated embodiment, thebody132 includes afirst segment142A, and second andthird segments142B,142C, respectively, extending therefrom. Specifically, thefirst segment142A includes afirst end146 and asecond end150. Thefirst segment142A has a length A (FIG. 4) measured between thefirst end146 and thesecond end150. First and second side edges154A,154B extend between the first and second ends146,150 of thefirst segment142A. Thesecond segment142B extends from thefirst end146 parallel to theconduit128, and thethird segment142C extends from thesecond end150 parallel to theconduit128. Additionally, the second andthird segments142B,142C extend parallel to and spaced apart from each other such that thebody132 has a U-shape. In other words, theburner body132 has a shape that may be termed as a horseshoe shape. The first, second, andthird segments142A-142C define a conduit-receivingspace158 located therebetween. Theconduit128 is in the conduit-receivingspace158 between the first andsecond segments142B,142C. Further, each of the first, second, andthird segments142A-142C includes thecurved surfaces134,138.
• With reference toFIG. 2, theburner assembly30 is positioned at a predetermined location within thecombustion chamber78. In the illustrated embodiment, theburner assembly30 is positioned at the predetermined location such that the first, second, andthird segments142A-142C are not located directly underneath the opening of theintermediate member86. Instead, the conduit-receivingspace158 is positioned directly underneath theflue110. This may reduce or eliminate the occurrence of condensation falling from theflue assembly26 directly onto theburner120. As such, theburner120 is shaped and positioned at the predetermined location to avoid contact with the condensation from theflue assembly26. 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 theburner120. As such, the U-shape of theburner120 may inhibit collection of condensation on the burner120 (i.e., screen member124), and/or reduce corrosion of theburner120 orscreen member124 due to condensation.
• Each of thesegments142A-142C includes a plurality of edges162 (FIG. 7) that form a top164 of thebody132. Thescreen member124 is movably coupled to the top164 of thebody132. Thescreen member124 includes afirst side166 and a second, opposite side (not shown). Thefirst side166 is in facing relationship with thecombustion chamber78. The second side is in facing relationship with the inner,curved surface138 of thebody132. As shown inFIG. 7, thescreen member124 is also curved or rounded such that thefirst side166 is convex (i.e., bends away from theinner surface138 of the body132). The second side of thescreen member124 compliments the curve of thefirst side166. Thescreen member124 is formed by a mesh material. Further, the illustratedscreen member124 comprises of a high temperature-resistant material such as metal (e.g., stainless steel Incoloy 601 metal). Thescreen member124 defines a zone ofcombustion168 of theburner assembly30.
• Thescreen member124 is selectively movable relative to the top164 of thebody132. In particular, the top164 of theburner body132 includes a flange170 (only a top side of which is shown inFIG. 7) extending around all of the plurality ofedges162 of thebody132. Theflange170 is configured to bend or fold over outer edges of thescreen member124 such that the edges of the screen member are positioned between theflange170. As such, thescreen member124 is movably retained to thebody132 of theburner120. Accordingly, thescreen member124 is configured to float relative to thebody132. This may relieve thermal stresses that occur within thescreen member124 as theburner120 is operated.
• Thebody132 and thescreen member124 cooperate to define an internal chamber174 (FIG. 8) of theburner assembly30. Theconduit128 extends from thebody132 and is fluidly connected to theinternal chamber174. As noted above, theconduit128 is positioned in the conduit-receivingspace158 between the second andthird segments142B,142C, respectively. Further, theconduit128 extends parallel to and spaced from the second andthird segments142B,142C, respectively. As such, theconduit128 extends through the conduit-receivingspace158. In the illustrated embodiment, theconduit128 is positioned at a center position along the length A of thefirst segment142A. In other embodiments, theconduit128 may be positioned at other axial positions along the length A of thefirst segment142A.
• With reference toFIG. 7, theconduit128 includes afirst end178 and asecond end182 opposite thefirst end178. Theconduit128 further includes apassage186 extending between thefirst end178 and thesecond end182. In the illustrated embodiment, thesecond side edge154B of thefirst segment142A defines an opening190 (FIG. 8), and thepassage186 is aligned with theopening190 at thesecond end182 of theconduit128. Accordingly, thepassage186 of theconduit128 is in fluid communication with theinternal chamber174 of thebody132/screen member124. Thefirst end178 of theconduit128 extends farther than each respective end of the second andthird segments142B,142C (i.e., it extends out of the conduit-receiving space158).
• With particular reference toFIGS. 5 and 6, theconduit128 extends from theburner body132 through thewall member82 of thecombustion chamber78. In the illustrated embodiment, theconduit128 extends through thedoor98 of thedoor assembly94. In other embodiments, theconduit128 may extend through thewall member82 at any other location of thecombustion chamber78. Accordingly, thefirst end178 of theconduit128 is positioned outside of thecombustion chamber78. Specifically, in the illustrated embodiment, a portion of theconduit128 is coupled by aplate member194 andfasteners198 to theinner surface102 of the door98 (FIG. 5). Theplate member194 is located closer to thefirst end178 of theconduit128 than thesecond end182. Theburner120 is supported in cantilever fashion in thecombustion chamber78 by theconduit128 which is rigidly mounted to thedoor98.
• With reference toFIGS. 3 and 4, anair guide member202 is coupled to thefirst end178 of theconduit128, outside of thecombustion chamber78 and, in this regard is an extension of theconduit128. In the illustrated embodiment, theair guide member202 is a venturi tube having a passage aligned with thepassage186 of theconduit128. Theair guide member202 forms aventuri portion206 of theconduit128. In the illustrated embodiment, theventuri portion206 is formed as a separate piece and coupled (e.g., by welding, etc.) to thefirst end178 of theconduit128. In this embodiment, thefirst end178 of theconduit128 receives a portion of theair guide member202. In other embodiments, theventuri portion206 may be formed as an integral portion of theconduit128 by shaping thefirst end178 of theconduit128 in the shape of a venturi. Theventuri portion206 draws air into theconduit128 in response to a flow of pressurized gas flowing through theventuri portion206.
• Thewater heater10 includes a gas supply assembly220 (FIG. 3). Thegas supply assembly220 includes avalve224 and agas pipe228 fluidly connected to thevalve224. In the illustrated embodiment, thevalve224 is supported by an outer surface of thetank18, and thegas pipe228 extends from thevalve224 toward theventuri portion206. In some embodiments, the end of thegas pipe228 may extend partially within theventuri portion206. Thegas valve224 is configured to selectively supply gas to theventuri portion206. In the illustrated embodiment, thegas valve224 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, thegas valve224 is configured to provide gas flow at a constant pressure of 3.5 inches water column. In other embodiments, thegas valve224 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 illustratedwater heater10 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.
• Thegas supply assembly220 is configured to selectively supply gas to theventuri portion206 such that air is drawn from the surrounding atmosphere into theventuri portion206 and into the conduit128 (e.g., by aspiration) (FIG. 4). A downstream direction is defined as a direction of the flow of gas and air into theconduit128 via theventuri portion206 to theinternal chamber174 of thebody132/screen member124. The air mixing with the gas upstream of the zone of combustion168 (i.e., the screen member124) may be termed as primary air.
• With reference toFIGS. 8-10, theburner assembly30 includes abaffle assembly236 positioned within theinternal chamber174. In the illustrated embodiment, thebaffle assembly236 includes a plurality ofbaffle members240,244 having abase baffle member240, and twocurved baffle members244 extending therefrom (FIG. 9). Thebase baffle member240 extends from thefirst side edge154A of thefirst segment142A of theburner body132 toward the second,opposite side edge154B (FIG. 8). More specifically, thebase baffle member240 extends toward theopening190. Thebase baffle member240 is aligned with a center of theopening190, and accordingly acenter axis248 of theconduit passage186. An edge252 (FIG. 10) of thebase baffle member240 conforms to the curvedinner surface138 of thebody132.
• Thecurved baffle members244 are coupled to thebase baffle member240. In the illustrated embodiment, eachcurved baffle member244 is coupled to a respective side of thebase baffle member240. In one example, spot welding is used to couple thecurved baffle members244 to thebase baffle member240. In other embodiments, thebase baffle member240 andcurved baffle members244 may be formed by a single, integral piece. In particular, thecurved baffle members244 each form a gull wing shape such that thebaffle assembly236 may be termed as a gull wing baffle assembly. Thebaffle assembly236 comprises of a metal material such as 20 or 22 gauge sheet aluminized steel. Thebaffle assembly236 is configured to direct the primary air/gas mixture (mixed upstream of the zone of combustion168) flowing from theconduit128 within theinternal chamber174 of theburner assembly30.
• With reference toFIGS. 3, 5, and 6, thewater heater10 includes apilot assembly260. The illustratedpilot assembly260 includes apilot burner264 and aspark ignitor268. As such, the illustratedpilot assembly260 may be referred to as a spark pilot. In other embodiments, thepilot assembly260 may utilize a resistance heating element instead of thespark ignitor268. The illustratedpilot assembly260 further includes athermocouple272. Thepilot assembly260 is supported by thewall member82 of thecombustion chamber78. In particular, thepilot assembly260 is supported by thedoor98 of thedoor assembly94. Thepilot burner264,spark ignitor268, andthermocouple272 extend from theinner surface102 of thedoor98 toward the burner assembly30 (i.e., the screen member124) within the combustion chamber78 (FIG. 6). An end of each of thepilot burner264,spark ignitor268, andthermocouple272 is positioned proximate the burner assembly30 (i.e., thesecond segment142B). In other embodiments, thepilot assembly260 may not include thethermocouple272.
• Apilot gas line276 extends from thegas valve224 to the pilot burner264 (FIG. 3) for selectively supplying gas to thepilot burner264. In the illustrated embodiment, thethermocouple272 is positioned above theburner120 relative to thelongitudinal axis42, and thespark ignitor268 is positioned next to thethermocouple272. Each of thepilot burner264,spark ignitor268, andthermocouple272 extends from outside ofcombustion chamber78 through thedoor98. As such, thepilot burner264,spark ignitor268, andthermocouple272 may be accessed by a user outside of thecombustion chamber78. In other embodiments, other components of thepilot assembly260 may be positioned through thedoor98 outside of thecombustion chamber78. This may facilitate cleaning, servicing, repair, and/or replacement of parts of thepilot assembly260.
• In operation, when there is a call for heat, thegas valve224 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 thegas valve224 into theair guide member202 such that the gas flows through theair guide member202 and subsequently theconduit128. 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 thescreen member124. In particular, the air that is being drawn into theair guide member202 is the primary air. Accordingly, the primary air dilutes the gas flow prior to the gas flow reaching the zone ofcombustion168.
• Thebaffle assembly236 directs the primary air/gas mixture entering theinternal chamber174 of theburner120 from theconduit128 to one side or the other of thebase baffle member240. In particular, thecurved baffle members244 separate the primary air/gas mixture into two paths, each path directed through one of the second andthird segments142B,142C, respectively, of theburner120. Accordingly, thebaffle assembly236 may facilitate the distribution and flow of the primary air/gas mixture through theinternal chamber174. More specifically, thebaffle assembly236 may facilitate maintaining an even balance of pressure underneath the screen member124 (i.e., zone of combustion168), thereby reducing and/or preventing overheating in localized areas of thescreen member124. Once the air/gas mixture flows past thescreen member124 in the downstream direction (e.g., the air/gas mixture enters thecombustion chamber78 via the screen member124) proximate the lightedpilot burner264, the air/gas mixture is ignited by thepilot burner264.
• Theburner assembly30 is configured such that the gas and the air are 100% premixed together upstream of the zone of combustion168 (i.e., the screen member124). In particular, all of the air entering and flowing through thecombustion system30,78 is introduced through theventuri portion206. The gas is entrained within the air resulting in a gas/air mixture ready for combustion at thescreen member124 of theburner assembly30. In particular, thevalve224, theconduit128 including theventuri portion206, and/or thescreen member124 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 thevalve224, an airflow rate of air controlled by theventuri portion206, a size (e.g., length, diameter, etc.) of theconduit128, and/or a velocity of the air/gas mixture exiting the burner120 (i.e., past the screen member124). For example, thescreen member124 is configured as a backpressure device to limit the exit velocity of the air/gas mixture through thescreen member124. More specifically, thescreen member124 includes a plurality of holes or perforations which define the amount of open surface area relative to a total surface area of thescreen member124. The open area (i.e., perforations or holes in the screen member124) relative to the total surface area of thescreen member124 determines the exit velocity of the air/gas mixture. As such, the amount of open area relative to the total surface area of thescreen member124 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 thescreen member124 is between 25% and 30%. In some embodiments, the open area relative to the total surface area of thescreen member124 is between 15% and 40%. Thescreen member124 is further configured to evenly distribute the air/gas mixture at any point located on the zone ofcombustion168. Accordingly, the air/gas mixture may be uniformly distributed on the zone ofcombustion168 such that an even loading on thescreen member124 and/or an even balance of pressure underneath the screen member124 (i.e., zone of combustion168) is achieved, thereby reducing and/or preventing overheating in localized areas of thescreen member124. The control of the exit velocity may also inhibit or prevent flashback.
• Additionally, the exit velocity controlled by thescreen member124 permits combustion to occur immediately downstream of thescreen member124 relative to the downstream direction such that the heat from the combustion flame is absorbed by thescreen member124, 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 thecombustion system30,78 is combusted at the zone of combustion168 (i.e., the screen member124), no secondary air is necessary to dilute any gas remaining downstream of thescreen member124. In addition, thepilot assembly260 is fed by natural convection of air flow through theburner assembly30. Thus, no additional openings in the bottom90 orcombustion chamber door98 are required to provide thepilot assembly260 with combustion air. Accordingly, a flammable vapor screen does not need to be provided at the bottom90 of thecombustion chamber78. In other words, there are no other openings in the bottom90 of thecombustion chamber78 for providing secondary air into thecombustion chamber78 that need to be covered by a flammable vapor screen. With only one opening in the combustion chamber78 (i.e., the openfirst end178 of the conduit128) to ingest flammable vapors, thewater heater10 may be configured to minimize the amount of flammable vapors entering thecombustion chamber78.
• During operation of the water heater, theburner body132 has a first, natural vibration frequency, and flames produced by the burner assembly at the zone ofcombustion168 oscillate at a second, predetermined vibration frequency. The first vibration frequency occurs due to pressure pulses within thecombustion chamber78. The second vibration frequency is based on the oscillation of flame speed pulsations (i.e., combustion rate fluctuations) that pass through thescreen member124. 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 theburner body132 and thescreen member124 may increase a stiffness of theburner120 to affect the first vibration frequency. In other words, the first vibration frequency is determined by the round-shape of theburner120. A radius of the curvature of thebody132 is selected such that the first vibration frequency is substantially greater than the second vibration frequency. In some embodiments, the shape of theburner120 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 theburner120 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 theburner120 is configured such that the first vibration frequency is at a frequency where the surfaces of theburner body132/screen member124 are not in resonance with the second vibration frequency or any of its harmonics. Further, the round shape of theburner120 is configured to maintain the first natural vibration frequency at a greater frequency than the second predetermined vibration frequency throughout operation of theburner120. Accordingly, burner resonance is inhibited or completely eliminated during operation.
• Accordingly, various embodiments of an atmosphericgas water heater10 having aburner assembly30 are described herein that is operable to use only primary air to dilute gases for combustion to heat the water within atank18. Theburner assembly30 further has a U-shape and is positioned within thecombustion chamber78 to avoid condensation produced in aflue assembly26. Further, theburner120 of theburner assembly30 is shaped to reduce or inhibit burner resonance. Thepilot assembly260 is accessible by a user outside of thecombustion chamber78 to facilitate service and replacement of parts. Operation of theburner assembly30 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 (20)

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 ofclaim 1, wherein the gas is only diluted by the air entering the burner assembly via the conduit.

3. The atmospheric gas water heater ofclaim 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 ofclaim 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 ofclaim 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 ofclaim 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 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, the body having a curved surface, 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,

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 ofclaim 7, wherein the gas is only diluted by the air entering the burner assembly via the conduit.

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

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

13. The atmospheric gas water heater ofclaim 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

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 pilot assembly is mounted outside of the combustion chamber.

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

16. The atmospheric gas water heater ofclaim 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 ofclaim 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 ofclaim 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 ofclaim 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 ofclaim 14, wherein the pilot assembly includes a pilot burner, a spark ignitor, and a thermocouple.

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