Flame Arrestor Assembly for a Gas Water Heater Appliance

The present subject matter relates generally to water heater appliances, and more particularly to combustion assemblies for gas water heaters.

Water heater appliances utilize a variety of energy sources to create hot water in commercial and residential settings, the energy sources including electric, solar, and various fuels. For example, natural gas and propane are preferred by some customers due to, for example, the relatively quick heating rate. These fuels are supplied as a gas that is burned in a combustion chamber to provide heat energy to raise the water temperature.

A conventional unpowered gas water heater may include a standing pilot light that will ignite the main gas burner when a call for heat is required. This combustion system may be a partially pre-mixed gas system. In this regard, the primary combustion air comes directly from the outside environment through a venturi located at the combustion chamber door and the secondary air for the pilot comes through the wrapper.

Notably, gas water heater appliances are commonly subject to strict emissions standards or other government regulations. For example, nitrogen oxides (NOx) emissions are often regulated by governments and municipalities, e.g., such that they must be lower than 10 nanograms per joule. In order to meet these emissions standards, the flow of secondary air needs to be restricted to create a more fuel rich mixture which decreases flame temperature and reduces NOx emissions. However, introducing such a restriction may cause an audible sound (i.e., combustion noise) that osculates at 1300 Hertz or may result in pilot flame instability.

Accordingly, a gas water heater with features for reduced NOx emissions is desirable. More specifically, a gas water heater with improved pilot light stability, reduced noise, and improved operation would be particularly beneficial.

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

In one exemplary embodiment, a gas water heater appliance is provided including a tank for storage of water for heating, a combustion chamber wall positioned below the tank and defining a combustion chamber and a pilot air inlet, a gas burner positioned within the combustion chamber to heat the water in the tank, and an arrestor assembly mounted to the combustion chamber wall above the pilot air inlet and below the gas burner. The arrestor assembly includes a flame arrestor and a restrictor plate positioned adjacent the flame arrestor, the restrictor plate defining a bottom of the combustion chamber and comprising one or more apertures that provide fluid communication between the pilot air inlet and the combustion chamber.

In another exemplary embodiment, an arrestor assembly for a gas water heater is provided. The gas water heater includes a combustion chamber and the arrestor assembly includes a flame arrestor and a restrictor plate positioned adjacent the flame arrestor, the restrictor plate defining a bottom of the combustion chamber and comprising one or more apertures that provide fluid communication between a pilot air inlet and the combustion chamber.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one element or component from another and are not intended to signify location or importance of the individual elements or components. The terms “includes” and “including” are intended to be inclusive in a manner similar to the term “comprising.” Similarly, the term “or” is generally intended to be inclusive (i.e., “A or B” is intended to mean “A or B or both”). In addition, here and throughout the specification and claims, range limitations may be combined or interchanged. Such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. The singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise.

Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “generally,” “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components or systems. For example, the approximating language may refer to being within a 10 percent margin (i.e., including values within ten percent greater or less than the stated value). In this regard, for example, when used in the context of an angle or direction, such terms include within ten degrees greater or less than the stated angle or direction (e.g., “generally vertical” includes forming an angle of up to ten degrees in any direction, such as, clockwise or counterclockwise, with the vertical direction V).

The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” In addition, references to “an embodiment” or “one embodiment” does not necessarily refer to the same embodiment, although it may. Any implementation described herein as “exemplary” or “an embodiment” is not necessarily to be construed as preferred or advantageous over other implementations. Moreover, each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention.

Except as explicitly indicated otherwise, recitation of a singular processing element (e.g., “a controller,” “a processor,” “a microprocessor,” etc.) is understood to include more than one processing element. In other words, “a processing element” is generally understood as “one or more processing element.” Furthermore, barring a specific statement to the contrary, any steps or functions recited as being performed by “the processing element” or “said processing element” are generally understood to be capable of being performed by “any one of the one or more processing elements.” Thus, a first step or function performed by “the processing element” may be performed by “any one of the one or more processing elements,” and a second step or function performed by “the processing element” may be performed by “any one of the one or more processing elements and not necessarily by the same one of the one or more processing elements by which the first step or function is performed.” Moreover, it is understood that recitation of “the processing element” or “said processing element” performing a plurality of steps or functions does not require that at least one discrete processing element be capable of performing each one of the plurality of steps or functions.

Referring now to the figures,illustrates a partial sectional, side view of an exemplary water heaterof the present invention.provides a schematic of a gas flow control system as may be used with the example water heater of. According to the illustrated embodiment, water heaterincludes a tankthat extends along a vertical direction V between a top walland a bottom wall. Tankdefines a generally cylindrical reservoir where water (e.g., identified generally by reference numeral) is supplied for heating and storage. Specifically, cool watermay be supplied into tankby an inlet linewhere it is heated before being discharged through an outlet line. According to an example embodiment, inlet lineand outlet lineare fluidly coupled to top wallof tankby one or more fluid connections, though other fluid supply/return configurations are possible and within the scope of the present subject matter.

Specifically, during operation of water heater, waterfrom an external water supplytravels through inlet lineand fills tank. Specifically, water heatermay include a cold water dip tubethat extends along vertical direction V towards bottom wallof tank. As described in more detail below, waterwithin tankmay be heated by combusting a fuel (e.g., natural gas or propane), and the heated watermay be stored in tankuntil demanded by a consumer, e.g., by opening a water consuming device such as an external fixture. In this regard, external fixturesmay include valves, faucets, appliances, or other water consuming devices fluidly coupled to water heaterthrough a water supply system of a residential or a commercial structure. Thus, when heated wateris requested by an external fixture, heated water travels upward through outlet linewhere it is supplied to the external fixturethrough one or more conduits or pipes of the water supply system.

To heat waterwithin tank, water heaterincludes a combustion assemblythat burns a fuel or fuel mixture, e.g., including propane, natural gas, etc. Specifically, combustion assemblyincludes a combustion chamberpositioned below bottom wallof tankin which a gas burneris centrally located. Gas burneris supplied with a gaseous fuel (e.g., propane or natural gas) from a gas supply lineincluding one or more flow regulating valves (e.g., such as a gas valveas shown in). The gas is directed into a venturi, and in the process, ambient air is drawn in through a combustion air inletwhere it is entrained with the fuel to create a fuel/air mixture that is injected into gas burnerthrough the venturi. The resulting mixture of air and gas is ignited and burned by gas burnerto heat bottom wallof tankand the watercontained within tank.

Hot combustion gas may be exhausted from combustion chamberthrough a vent or fluecentrally located within tank. Heat exchange with fluealso helps heat waterin tank. A bafflemay further promote this heat exchange between combustion gases and water. Gas exits water heaterthough a vent hood, which may be connected with additional vent piping (not shown) to eject the combustion gases to an external environment.

According to example embodiments, water heatermay further include an anode rodthat provides protection against corrosion attacks on tankand other metal components of water heater. In addition, a pressure relief valveprovides for a release of water from tankin the event the pressure rises above a predetermined amount. Other safety features may be included while remaining within the scope of the present subject matter.

A thermostatmay be positioned within tankto measure the temperature of waterin tankand provide a signal to gas control valve module. As used herein, “a signal” is not limited to a single measurement of temperature and, instead, may include multiple measurements over time or continuous measurements over time. The signal may be provided through, for example, changes in current, voltage, resistance, or others. Depending upon whether the desired temperature has been reached as determined (e.g., from the signal from thermostat), gas control valve moduleregulates the flow of gas to gas burnerthrough gas supply line.

Referring now to, combustion chamberis formed by a chamber wallthat at least partially encloses combustion chamberand may also provide support for tankalong a top edge. As shown, chamber wallencircles combustion chamberand is spaced apart from gas burner. In addition, water heatermay include an outer skirt or a cabinetthat surrounds both combustion chamber walland tank, though it should be appreciated that these features may alternatively be formed as part of cabinet. As illustrated for example in, cabinetmay define an air intakefor supplying ambient air that facilitates operation of water heater.

As shown, water heaterincludes a pilot burnerthat provides a pilot lightto ignite a mixture of air and fuel at gas burnerwhen a gas valve (e.g., as part of gas control valve moduleor provided as a separate component) is open. An igniteris positioned adjacent to pilot burnerand generates a spark used to ignite gaseous fuel and provide pilot light. Gaseous fuel for pilot burneris supplied by a pilot burner fuel line. Gas valve control modulemay control the flow of gaseous fuel through pilot burner fuel lineand the flow of gas to gas burnerthrough gas supply line. Alternatively, a dedicated pilot valve may be used to regulate the flow of gas to pilot burner.

In certain embodiments, gas valve control moduleincludes at least one controller. By way of example, controllermay include memory and one or more processing devices such as microprocessors, CPUs or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of water heateras further described herein. The memory can represent random access memory such as DRAM, or read only memory such as ROM or FLASH. The processor executes programming instructions stored in the memory. The memory can be a separate component from the processor or can be included onboard within the processor. Alternatively, controllermay be constructed without using a microprocessor (e.g., using a combination of discrete analog or digital logic circuitry—such as switches, amplifiers, integrators, comparators, flip-flops, AND gates, and the like) to perform control functionality instead of relying upon software.

In some embodiments, a chamber sensor, which is generally configured to detect temperature, is positioned at, on, or adjacent to the combustion chamber. For instance, chamber sensormay be attached to chamber wall(e.g., supported thereon). As shown, chamber sensormay be disposed, at least in part, within combustion chamber. Generally, chamber sensormay be any suitable temperature sensor (e.g., thermocouple, thermistor, IR sensor, etc.) configured to detect a temperature within combustion chamber. For instance, an output voltage from chamber sensormay be proportional to the temperature within the combustion chamberor at chamber sensor. The voltage signal transmitted to controller(e.g., and may be interpreted thereby) through conductors may thus represent representing the measured chamber temperature.

Further separate from or in addition to chamber sensor, water heatermay include an ambient sensor. Ambient sensormay be spaced apart from chamber sensor. In some embodiments, ambient sensoris attached to tank, such as indirectly or through the gas valve control module(e.g., such that the ambient sensoris generally fixed relative to the tank). For instance, ambient sensormay be disposed within gas valve control moduleon or in operable (e.g., electrical or wireless) communication with controller. Generally, ambient sensoris configured to detect temperature outside of combustion chamber(e.g., directly or indirectly). In some such embodiment, ambient sensorincludes or is provided as a suitable temperature sensor (e.g., thermocouple, thermistor, IR sensor, etc.) configured to detect temperate outside of combustion chamber. The voltage signal from ambient sensormay be transmitted to controller(e.g., and may be interpreted thereby). In additional or alternative embodiments, ambient sensorcommunicates (e.g., wirelessly) with a separate probe or database (e.g., weather station) to receive an ambient temperature value detected apart from the tankor water heatergenerally.

In exemplary embodiments, water heaterincludes gas valvepositioned along gas supply line. According to example embodiments, gas valvemay be incorporated as part of gas control valve moduleor may be a separate component. Controlleris in communication with gas valveto control the flow of gas therethrough by determining when gas valveis energized. For this exemplary embodiment, gas valvemay operate so that when energized, gas valveis fully open to allow a flow of gaseous fuel to gas burner. When not fully energized, gas valveis fully closed (i.e. a “fail-closed” type valve) so as to prevent the flow of gaseous fuel to gas burner.

During use, opening or closing of gas valvemay generally be directed or controlled by controller. For instance, gas valvemay be directed to the open position to create a flame at gas burner. Controllermay receive one or more signals (e.g., from thermostat) to determine whether the temperature of water in tankhas reached a desired setpoint temperature. In response to the same, the controllermay direct the gas valveto the closed position. In some embodiments, an open interval (i.e., time period in which gas valveis continuously opened or a flame is generated) may be demarcated or observed as a single cycle.

Referring now also to, aspects of combustion assemblywill be described in more detail according to example embodiments of the present subject matter. More specifically, aspects of the present subject matter are generally directed to an arrestor assemblyfor use with combustion assemblyto address various problems described herein. Specifically, arrestor assemblymay be mounted to the combustion chamber walland generally defines a bottom boundary of combustion chamber. According to the illustrated embodiment, combustion chamber wallmay generally define a pilot air inlet, e.g., which may include a plurality of perforations or apertures defined around a circumference of a bottom of combustion chamber wall. In general, arrestor assemblymay be positioned above pilot air inletand below gas burnerwithin combustion assembly.

According to the illustrated embodiment, arrestor assemblymay generally include a flame arrestorand a restrictor platepositioned adjacent flame arrestorand defining a bottom of combustion chamber. Specifically, according to the example embodiment, flame arrestoris positioned below restrictor plateand is generally configured to allow free passage of air and/or gases while preventing a flame from traveling therethrough. For example, flame arrestormay be a mesh screen, a perforated plate, or any other structure that defines a plurality of small passages through which gases may flow while the passage of flames is prevented. For example, as shown schematically in, a flow of pilot airmay pass through flame arrestor, as described in more detail below.

Specifically, restrictor platemay define one or more aperturesthat provide fluid communication between pilot air inletand combustion chamber. According to the illustrated embodiment, aperturesare defined on a raised embossmentof restrictor plate. In this regard, raised embossmentmay be defined in the center of restrictor platefor directing the flow of pilot airtoward pilot burner. In this regard, for example, raised embossmentmay be positioned directly below pilot lightfor supporting combustion of pilot burner.

Notably, as explained briefly above, supplying pilot aironly through aperturesmay generate audible sounds and/or may generate pilot flame instability, resulting in the potential failure of water heaterand consumer dissatisfaction. Specifically, combustion noise may oscillate at approximately 1300 Hz when pilot airis supplied only through apertures. Accordingly, aspects of the present subject matter are directed to features of arrestor assemblydesigned to carefully regulate the flow of pilot airand the pressure drop across arrestor assembly, thereby providing improved flame stability and reduced operation noise.

Specifically, as best shown in, restrictor platemay be formed such that a gapis defined or formed between restrictor plateand combustion chamber wall. In this manner, pilot airmay flow both through aperturesand through gapinto combustion chamberto facilitate operation of pilot burner. According to example embodiments, a nominal length of gap(e.g., an average about the circumference of restrictor plate) may be between about 0.01 and 0.2 inches, between about 0.02 and 0.1 inches, between about 0.03 and 0.07 inches, or about 0.05 inches. In addition, according to an example embodiment, the total cross-sectional area of the one or more aperturesand gapmay be between about 1 and 15 square inches, between about 2 and 10 square inches, between about 3 and 8 square inches, or about 5 square inches.

It should be appreciated that gapmay be formed in any suitable manner. For example, according to the illustrated embodiment as best shown in, restrictor platemay define an arcuate profile within a vertical plane. In this regard, for example, restrictor platemay be formed as a hyperbolic paraboloid that is not flat within a horizontal plane. Forming restrictor platein this manner may create gapsbetween restrictor plateand combustion chamber wall, as described above. Although a curved or bent restrictor plateis illustrated, it should be appreciated that according to alternative embodiments, gapmay be formed by punching recesses around a perimeter of restrictor plateor machining restrictor platein any other suitable manner to define the desirable size of gap.

Referring again to, arrestor assemblymay be secured within combustion chamber wallby roll forming or any other suitable process. For example, combustion chamber wallmay be roll formed around flame arrestorsecure flame arrestorto combustion chamber wall. Restrictor platemay be supported on top of flame arrestor. In addition, according to the illustrated embodiment, a burner support bracketmay be mounted on top of restrictor platefor supporting gas burner. For example, burner support bracketmay define a plurality of weld locationswhere burner support bracketmay be welded or joined (e.g., by tack welding) to both restrictor plateand flame arrestor. Gas burnermay then be seated on top of burner support bracket. Notably, this construction improves pilot flame stability and reduces combustion noise for improved consumer satisfaction and appliance performance.

As explained herein, aspects of the present subject matter are generally directed to an ultra-low nitrogen oxide (NOx) emission storage gas water heater including a combustion chamber that includes multiple air entrances for good combustion that reduces NOx emissions. One air inlet is defined through a bottom member with strategically placed perforations, through which air enters around the gas burner through a perforated, centrally located arrestor plate. The optimized air opening reduces NOx formation, and a total open area may include apertures in the punched section plus the area created by the gap around the perimeter. The arrestor plate may undergo a stamping procedure which transforms a flat metal plate into one with contours. These contours in the metal reduce the pressure drop across the perforated arrestor plate, which in turn enhances the stability of the pilot flame during the ignition phase of a gas burner. The small air gap around the perimeter of the combustion chamber skirt provides a stable supply of secondary combustion air that stabilizes combustion oscillations and eliminates combustion noise.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.