SINGLE PASS HIGH-EFFICIENCY CONDENSING WATER HEATER

FIELD OF THE DISCLOSURE

This disclosure relates to water heaters and, more particularly, to high-efficiency water heaters employing a single-pass heat exchanger.

BACKGROUND OF THE DISCLOSURE

Commercial water heaters typically heat water by generating tens of thousands, and even hundreds of thousands, of BTUs. For many years, manufacturers of water heaters, and especially manufacturers of water heaters to be used in commercial applications, have sought to increase the efficiency of the exchange of this heat energy from burned fuel to the water contained in the water heater. Accordingly, efficient heat exchange has long been an object of commercial water heater manufacturers.

SUMMARY OF THE DISCLOSURE

According to an aspect of the present disclosure, a heating system for a water heating appliance includes a heater for generating heated process air, a blower for delivering the heated process air through an airflow path, a flue that defines an upstream section of the airflow path, a heat exchange structure disposed downstream of the flue and defining a medial section of the airflow path, and a condensing section that defines a downstream section of the airflow path and is disposed downstream of the heat exchange structure. The heat exchange structure includes a heat exchange portion having airflow obstructions that generate a turbulence and transfer heat from the heated process air to a media surrounding an outer surface of the heat exchange structure. The airflow path within the heat exchange portion extends outward and generally perpendicular to a direction of the airflow path within the flue.

According to another aspect of the present disclosure, a single pass condensing water heating appliance includes an outer housing that defines a fluid reservoir therein, a heater for heating process air to define heated process air, a blower coupled to the outer housing that delivers the heated process air through an airflow path that extends through, and is in thermal communication with, the fluid reservoir, a flue disposed within the outer housing and defining an upstream section of the airflow path, a heat exchange structure having a transition that is positioned proximate an end of the flue, and a condensing section attached to the heat exchange structure and defining a downstream section of the airflow path. The heat exchange structure defines a medial section of the airflow path and includes an interior chamber having a plurality of airflow obstructions that generate a turbulence within the heated process air that increases a residency of the heated process air within the heat exchange structure. The plurality of airflow obstructions transfers heat from the heated process air to a media within the fluid reservoir.

According to another aspect of the present disclosure, a heating system for a water heating appliance includes a flue that defines an upstream section of an airflow path that directs heated process air along a central axis, an air delivery system that delivers the heated process air into the airflow path via the flue, a heat exchange structure attached to an end of the flue opposite the air delivery system, and a condensing section that is attached to the heat exchange structure and defines a downstream section of the airflow path. The heat exchange structure defines a medial section of the airflow path and has a heat exchange portion that directs the heated process air outward from the end of the flue and in a direction generally perpendicular to the central axis within the flue. The heat exchange structure further includes airflow obstructions that transfer heat from the heated process air, through a wall of the heat exchange structure and to a media surrounding an outer surface of the wall of the heat exchange structure.

According to another aspect of the present disclosure, a heating system for a water heating appliance includes a heater for heating process air, a blower for delivering the process air through an airflow path, a flue that defines an upstream section of the airflow path, and a heat exchange structure disposed downstream of the flue and defining a medial section of the airflow path. The heat exchange structure includes a heat exchange portion having airflow obstructions that transfer heat from the process air to water surrounding an outer surface of the heat exchange structure. A condensing section is included that defines a downstream section of the airflow path that is disposed downstream of the heat exchange structure. A diverter plate is disposed below the heat exchange structure for collecting condensate from the process air.

According to another aspect of the present disclosure, a water heating appliance includes an outer housing that defines a fluid reservoir therein, a blower attached to the outer housing that delivers process air through an airflow path that extends through and is in thermal communication with the fluid reservoir, and a heater for heating the process air. The water heating appliance also includes a flue disposed within a top region of the outer housing and that defines a top section of the airflow path. A heat exchange structure is attached to an end of the flue and defines a medial section of the airflow path. The heat exchange structure includes a resistive section having a plurality of heat exchange fins that direct the process air in a cyclonic motion through the plurality of heat exchange fins and between the flue and perimeter outlets of the heat exchange structure. The plurality of heat exchange fins transfer heat from the process air to water within the fluid reservoir. A condensing section is coupled with the perimeter outlets of the heat exchange structure. The condensing section defines a downstream section of the airflow path.

According to yet another aspect of the present disclosure, a heat exchange structure of a water heating appliance includes a convex outer wall that defines a central adapter, and an inner wall that opposes the convex outer wall and defines a heat exchange portion. The inner wall defines perimeter outlets. A plurality of heat exchange fins extends between the convex outer wall and the inner wall. The plurality of heat exchange fins directs the process air in a cyclonic motion from the central adapter, through the plurality of heat exchange fins and to the perimeter outlets. A lower plate is disposed below the inner wall and at least partially defines the perimeter outlets and a condensate area.

These and other features, advantages, and objects of the present disclosure will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a side perspective view of a water heating appliance that incorporates an aspect of the heat exchanger;

FIG. 2 is a side elevation view of the water heating appliance of FIG. 1;

FIG. 3 is a schematic perspective view of a water heating appliance and showing an aspect of the heat exchanger disposed within an outer housing;

FIG. 4 is a cross-sectional view of the water heating appliance of FIG. 1 taken along line IV-IV;

FIG. 5 is a perspective view of an aspect of a heat exchanger for a water heating appliance;

FIG. 6 is an enlarged cross-sectional view of an exemplary heat exchanger for the water heating appliance and showing the flue connected to an aspect of the heat exchange structure;

FIG. 7 is a top perspective view of an aspect of the restrictor plate for an aspect of the heat exchange structure;

FIG. 8 is a cross-sectional view of the water heating appliance of FIG. 2, taken along line VIII-VIII and showing the transition from the heat exchange structure to the condensing section of the water heater;

FIG. 9 is a bottom perspective view of an aspect of the heat exchange structure and showing an exemplary configuration of the heat exchange fins;

FIG. 10 is a top perspective view of the heat exchange structure of FIG. 9;

FIG. 11 is a schematic bottom plan view of the heat exchange structure of FIG. 9 and showing a flow of heated process air through the plurality of heat exchange fins of the heat exchange structure;

FIG. 12 is a cross-sectional view of the heat exchange structure of FIG. 9, taken along line XII-XII and showing an attachment interface between the heat exchange fins and the outer wall of the heat exchange structure;

FIG. 13 is a cross-sectional view of the heat exchange structure of FIG. 9 and showing another attachment mechanism for attaching the plurality of heat exchange fins to the heat exchange structure;

FIG. 14 is a bottom perspective view of an aspect of the heat exchange structure;

FIG. 15 is a bottom plan view of the heat exchange structure of FIG. 14;

FIG. 16 is a cross-sectional view of the heat exchange structure of FIG. 15, taken along line XVI-XVI and showing the plurality of heat exchange fins set within circular frames;

FIG. 17 is an exploded perspective view of the heat exchange structure of FIG. 14;

FIG. 18 is an enlarged view of the plurality of heat exchange fins of the heat exchange structure of FIG. 17 taken at area XVIII;

FIG. 19 is a bottom perspective view of an aspect of the heat exchange structure having a plurality of circular frames with bottom flanges that are connected to form an integral inner wall of the heat exchange structure;

FIG. 20 is a top perspective view of the heat exchange structure of FIG. 19;

FIG. 21 is a cross-sectional view of the heat exchange structure of FIG. 20 taken along line XXI-XXI;

FIG. 22 is a cross-sectional view of the heat exchange structure of FIG. 20 taken along line XXII-XXII;

FIG. 23 is a cross-sectional view of the heat exchange structure of FIG. 20 taken along line XXIII-XXIII;

FIG. 24 is an enlarged cross-sectional view of the heat exchange structure of FIG. 23 taken at area XXIV;

FIG. 25 is a cross-sectional view of an aspect of the heat exchange structure;

FIG. 26 is an enlarged schematic cross-sectional view of the heat exchange structure of FIG. 25, taken at area XXVI, and showing movement of the heated process air through the heat exchange portion;

FIG. 27 is an exploded perspective view of the heat exchange structure of FIG. 25;

FIG. 28 is an enlarged perspective view of an aspect of an innermost airflow obstruction of the heat exchange structure of FIG. 27;

FIG. 29 is an enlarged perspective view of an aspect of an outer airflow obstruction of the heat exchange structure of FIG. 27;

FIG. 30 is a perspective view of an aspect of a condensing section of a heat exchanger; and

FIG. 31 is an exploded perspective view of an aspect of a condensing section of the heat exchanger.

The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles described herein.

DETAILED DESCRIPTION

As required, detailed embodiments of the present disclosure are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to a detailed design; some schematics may be exaggerated or minimized to show function overview. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the concepts as oriented in FIG. 2. However, it is to be understood that the concepts may assume various alternative orientations, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise.

The present illustrated embodiments reside primarily in combinations of method steps and apparatus components related to a water heating appliance that incorporates a heat exchanger having a heat exchange structure that utilizes a plurality of heat exchange fins set within a generally spiral configuration to promote greater residency of combustion gases within the heat exchange structure to transfer heat from the combustion gases for delivery into the water disposed around the heat exchange structure. Accordingly, the apparatus components and method steps have been represented, where appropriate, by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Further, like numerals in the description and drawings represent like elements.

As used herein, the term “and/or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items, can be employed. For example, if a composition is described as containing components A, B, and/or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

In this document, relational terms, such as “first” and “second,” “top” and “bottom,” and the like, are used solely to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by “comprises . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

As used herein, the term “about” means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. When the term “about” is used in describing a value or an end-point of a range, the disclosure should be understood to include the specific value or end-point referred to. Whether or not a numerical value or end-point of a range in the specification recites “about,” the numerical value or end-point of a range is intended to include two embodiments: one modified by “about,” and one not modified by “about.” It will be further understood that the end-points of each of the ranges are significant both in relation to the other end-point, and independently of the other end-point.

The terms “substantial,” “substantially,” and variations thereof as used herein are intended to note that a described feature is equal or approximately equal to a value or description. For example, a “substantially planar” surface is intended to denote a surface that is planar or approximately planar. Moreover, “substantially” is intended to denote that two values are equal or approximately equal. In some embodiments, “substantially” may denote values within about 10% of each other, such as within about 5% of each other, or within about 2% of each other.

As used herein the terms “the,” “a,” or “an,” mean “at least one,” and should not be limited to “only one” unless explicitly indicated to the contrary. Thus, for example, reference to “a component” includes embodiments having two or more such components unless the context clearly indicates otherwise.

Aspects of the present invention advantageously provide high-efficiency and/or condensing water heaters including a heat exchanger that facilitates uniform application and easy inspection of anticorrosive coatings.

To generate heat for heating water, water heaters according to aspects of this invention receive a source of energy, such as fuel. This fuel can take the form of oil or natural gas, which is consumed by a burner to heat the water. The burner creates hot combustion or exhaust gases, which are vented through flue tubes passing through a water tank of the water heater. These flue tubes may include baffles or fins designed to create a higher temperature flux (rate of thermal transfer) near the flue wall. These fins or baffles can also enhance the level of turbulence experienced by the hot exhaust gases. This increase in turbulence, in turn, also increases the residency of the hot exhaust gases within certain areas, thereby increasing the efficiency of the water heater in transferring heat from the hot exhaust gases into the water surrounding the water heater.

As heat exchange efficiency increases, such increased efficiency gives rise to condensation of water vapor from the products of combustion. More specifically, upon burning of a mixture of fuel and air, water, in the form of vapor, is formed as a constituent of the products of combustion. As the temperatures of the combustion gases decrease as the result of successful exchange of heat from the combustion gases to water in the water heater, the water vapor within the combustion gases tends to be condensed through a phase change from gas water vapor to liquid condensate. The greater the decrease in temperature, the more condensate is formed, as described herein. In other words, as the temperatures of the combustion gases decrease, as a direct result of increasingly efficient exchange of heat energy to the circulated water, the amount of condensate formed on the heat exchange surfaces also increases.

Referring generally to non-limiting exemplary embodiments selected for illustration in FIGS. 1-31, a water heater 100 may include a water storage tank 110 (or reservoir 532) configured to store water 530 to be heated. Water heater 100 has a combustion chamber 150, and a heat exchanger 130 configured to receive combustion gases 612 from the combustion chamber 150 and to transfer heat 514 from the heated combustion gases 612 to water 530 stored in the water storage tank 110. The heat exchanger 130 includes a flue tube 132 defining part of an airflow path 524 for the heated combustion gases 612 received from the combustion chamber 150. The heated combustion gases 612 are also referred to herein as heated process air 910.

The flue tube 132 has a plurality of heat conductive airflow obstructions 548, typically in the form of a flue set 574 of heat exchange fins 138. The heat exchanger 130 includes a sensible heat exchange area 930 that includes at least a portion of the flue tube 132. The sensible heat exchange area 930 includes an interior chamber 1030 defined within a heat exchange structure 542. The interior chamber 1030 includes a portion of the plurality of air flow obstructions 548, of the airflow path 524.

The heat exchanger 130 further has a latent heat exchange area 932 coupled to the heat exchange structure 542. The latent heat exchange area 932 includes a plurality of condensing tubes 140.

Referring to FIGS. 1-8, an exemplary embodiment of water heater 100 includes a water storage tank 110, a gas-fired burner 150, a single-pass condensing heat exchanger 130, a blower 170, and a condensate collector 180, such as a pan or other containing volume. Additional details of the components of water heater 100 are found herein.

Water storage tank 110, also referred to herein as a reservoir 532, is configured to store water 530 that is to be heated.

The water storage tank 110 has a top portion 112, a bottom portion 114, and a side wall 116 extending between the top portion 112 and the bottom portion 114. Generally, the top portion 112, the bottom portion 114, and the side wall 116 may form any shape that permits water 530 to be stored therein. The top portion 112 and/or the bottom portion 114 may be convex, flat, conical, semi-spherical, or any other shape suitable for water heater designs. Preferably, the side wall 116 is curved and may, e.g., form a cylindrical periphery of water storage tank 110. In at least one embodiment, however, side wall 116 optionally forms a rectangular prism. Side wall 116 may also have flat side portions and/or curved side portions.

Water storage tank 110 includes one or more cold water inlets 160 and/or one or more hot water outlets 162. The cold water inlet 160 may be configured to deliver unheated water 530 into water storage tank 110. The hot water outlet 162 may be coupled to a heated water supply line (not shown) for distributing heated water 590 from water storage tank 110. An aperture 106 may be provided in a side wall 116 of the tank (e.g., for providing a clean-out cover). Still further, water heater 100 may further include a gas-fired burner 150 in a top region 102 of the water heater 100. The single-pass condensing heat exchanger 130 extends within the water storage tank 110 from the top portion 112 of the water storage tank 110 to the bottom portion 114 of the water storage tank 110.

Although water heater 100 is configured as a downward fired water heater, water heaters in accordance with the present invention may be configured as an upward or downward fired water heater. In this configuration, as shown in FIGS. 1-3, burner 150 may be positioned at elevations near a bottom region 104 or near a top region 102 of water heater 100. In one embodiment, burner 150 may be positioned within the water heater 100, such as above top portion 112 of water storage tank 110.

Additionally, or optionally, water heater 100 includes gas burner 150 and a spark rod or other ignition source (not shown) that is positioned adjacent the gas burner 150 for igniting the fuel. Burner 150 is in fluid communication with the heat exchanger 130, which is positioned at least partially within the interior of water storage tank 110, such that the heated combustion gases 612 flow through at least a portion of the water storage tank 110. For example, heat exchanger 130 may extend from the bottom region 104 to the top region 102 of water storage tank 110 or vice versa.

In an exemplary embodiment, the heat exchanger 130 may include an upstream section 400, a downstream section 402, and a medial section 404. Heat exchanger 130 is configured to receive the combustion gases 612 directed by the blower 170 for the transfer of heat 514 from the combustion gases 612 to water 530 in the water storage tank 110.

As illustrated in FIGS. 1-8, the upstream section 400 extends within the water storage tank 110 and downward from the top portion 112 of the water storage tank 110. The upstream section 400 includes the flue tube 132 into which the combustion gases 612 are directed by the blower 170 for the transfer of heat 514 from the combustion gases 612 to water 530 in the water storage tank 110.

Additionally, or optionally, the flue set 574 of heat exchange fins 138 are in thermal communication with, and typically attached to, the flue tube 132 to supplement the transfer of heat 514 from the combustion gases 612 to water 530 in the water storage tank 110. Still further, the upstream section 400 can include baffling (not shown) thermally coupled to the flue tube 132 to supplement the transfer of heat 514 from the combustion gases 612 to water 530 in the water storage tank 110. In this manner, the baffles, fins, and other airflow obstructions 548 can enhance turbulence in the combustion gases 612 traveling therethrough. The airflow obstructions 548 can enhance turbulence in combustion gases 612, with the mean velocity through the heat exchanger 130 remaining substantially consistent at a certain water heater input. As discussed herein, water heater 100 includes fins 138, baffles and other airflow obstructions 548 for promoting the transfer of heat 514 and/or modifying the flow of the combustion gas 612 throughout the heat exchanger 130. For example, fins 138 may be provided to promote turbulent flow, modify the flow rate, and/or increase the surface area for transferring heat 514.

As depicted in FIGS. 1-8, the downstream section 402 extends within the water storage tank 110 and downward to the bottom portion 114 of the water storage tank 110. The downstream section 402, made up of the condensing tubes 140, receive the combustion gases 612 from the heat exchange structure 542 of the medial section 404 of the sensible heat exchange area 930. The condensing tubes 140 each include a condensing set 576 of the heat exchange fins 138, or other airflow obstructions 548. These airflow obstructions 548 are made of a thermally conductive material that transfers heat 514 from the combustion gases 612 to water 530 in the water storage tank 110. As described herein, the heat conductive structures or airflow obstructions 548 are thermally coupled within the condensing tubes 140 to supplement the transfer of heat 514 from the combustion gases 612 to water 530 in the water storage tank 110.

In the illustrated embodiment of FIGS. 1-8, twenty-two (22) condensing tubes 140 are provided, but the number of condensing tubes 140 can be smaller or greater depending on factors including the diameter of the condensing tubes 140, the length of the condensing tubes 140, the surface area or shape of the condensing tubes 140, the desired transfer of heat 514 to be provided by condensing tubes 140, and/or other factors or specifications (e.g., water heater input). There can be as few as one condensing tube 140 and as many as 30 or more condensing tubes 140. The number of condensing tubes can be adjusted based on size and space constraints, water heater input, desired water heater output, and other factors and constraints.

By way of example and not limitation, there may be a limitation on the maximum number of condensing tubes 140 based on manufacturing limitations, including manufacturing processes and the size of the water heater and its components. For example, in one embodiment twenty-two (22) condensing tubes 140 were fit on a 22″ diameter flat disc that can be used as a lower heat exchange surface 306 (described below) that defines respective outlets 558 of the medial section 404. Additionally, the number of condensing tubes 140 may be selected to ensure following the best welding practices for flue insertion and weld automation.

The diameter of the condensing tubes 140 may be constant along their length or may vary. Also, the diameter of the condensing tubes 140 may be the same as one another or different. In one non-limiting example, the condensing tubes 140 have an outer diameter of 2 inches, but may be smaller or larger in diameter. Condensing tubes 140 preferably have an outer diameter of 0.5 to 3 inches, and more preferably a diameter of 1 to 2 inches.

The condensing tubes 140 may extend within the water storage tank 110 toward the bottom portion 114 of the water storage tank 110. A portion of each of the condensing tubes 140 may exit the water storage tank 110 through at least one aperture in a base of the water storage tank 110. Also, another aperture in the water storage tank 110 can be provided (e.g., a hot water outlet 162 for heated water 590 defined in top portion 112 of the water storage tank 110).

Referring again to FIGS. 1-8 and 25-31, the medial section 404 is interposed between the upstream section 400 and the downstream section 402. In certain aspects of the device, the medial section 404 can be defined as a portion of the upstream section 400, which cooperatively form the sensible heat exchange area 930. Although the figures depict a single medial section 404, a plurality of medial sections 404 may be provided, each of which may be connected to the single flue tube 132 of the upstream section 400. In an exemplary embodiment, the medial section 404 includes an inlet 302, positioned to receive the combustion gases 612 from the upstream section 400, and a plurality of respective outlets 558 positioned to deliver the combustion gases 612 to the downstream section 402. The respective outlets 558 correspond to the condensing tubes 140 to transfer the combustion gases 612 from the medial section 404 to the condensing tubes 140.

In addition, the medial section 404 extends radially outwardly relative to the upstream section 400 and the downstream section 402, thereby reducing the area for upward flow of water 530 in the water storage tank 110 from an elevation corresponding to the downstream section 402 to an elevation corresponding to the upstream section 400. In this manner, relatively cooler water 592 remains in a bottom portion 114 of the interior of the water storage tank 110 while warmer water typically resides in an top portion 112 of the water storage tank 110. To achieve this, in an exemplary embodiment, the aspect ratio of a height of the medial section 404 to the diameter of a medial section 404 is approximately 0.3 or less. Still further, in this configuration, an easier water baffling system is provided via pushing cold water flow around the smaller diameter condensing tubes 140, if needed. As described herein, using heat convection, the heated water 590 tends to elevate within the water storage tank 110 and the cooler water 592 tends to descend within the water storage tank 110.

Additionally, the shape of the heat exchange structure 542 limits or meters the flow of heated water 590 in an upward direction from an area below the heat exchange structure 542 of the medial section 404 to an area above the heat exchange structure 542. Similarly, the shape of the heat exchange structure 542 also limits or meters the downward movement of cooler water 592 from the area above the heat exchange structure 542 to the area below the heat exchange structure 542. This limitation on the movement of water 530 in a vertical direction within the water storage tank 110 allows the cooler water 592 to remain near the condensing tubes 140 for a longer period of time. This increased residency of the cooler water 592 near the condensing tubes 140 allows this cooler water 592 to receive greater amounts of heat 514 from the condensing tubes 140. After receiving a sufficient amount of heat 514, enough convection is created to allow the vertical motion of the water 530 having different temperatures to move within the water storage tank 110 and around the heat exchange structure 542.

In this configuration, the medial section 404 includes an upper heat exchange surface 304 and a lower heat exchange surface 306. The upper heat exchange surface 304 defines the inlet 302 of the medial section 404. The upper heat exchange surface 304 is coupled to the upstream section 400 and is configured to transfer heat 514 from the combustion gases 612 to water 530 in the water storage tank 110. As described herein, the upper heat exchange surface 304 can have a planar surface, a domed surface, a conical surface, combinations thereof, or other similar shape that provides for an enlarged interior chamber 1030 of the heat exchange structure 542. This enlarged interior chamber 1030 provides for movement of the combustion gases 612 in a direction that is outward with respect to the flue tube 132. This outward direction of the combustion gases 612 within the heat exchange structure 542 can be perpendicular to the flue tube 132 or generally perpendicular to the flue tube 132. The term generally perpendicular includes perpendicular as well as oblique angles ranging from less than 90 degrees (perpendicular) to approximately 45 degrees, or approximately 30 degrees or other similar angle indicative of an outward motion of the combustion gases 612. This motion of the combustion gases 612 within the heat exchange structure 542 is described more fully herein.

The lower heat exchange surface 306 defines the perimeter outlets 706 of the medial section 404. The lower heat exchange surface 306 is coupled to the upper heat exchange surface 304 to at least partially define the interior chamber 1030. Within this interior chamber 1030, heat conductive airflow obstructions 548 are positioned. Additionally, the heat conductive airflow obstructions 548 are thermally coupled to an underside of the outer wall 572 that defines the upper heat exchange surface 304. The positioning of the heat conductive airflow obstructions 548 increases the thermal flux of heat 514 between the interior of the heat exchange structure 542 and the water 530 surrounding the heat exchange structure 542. In this manner, the heat conductive airflow obstructions 548 supplement the transfer of heat 514 from the combustion gases 612 to the water 530 in the water storage tank 110.

Still further, the medial section 404 includes a transition 1040 extending within the interior chamber 1030 of the heat exchange structure 542. This transition 1040 is positioned to divert or otherwise redirect the combustion gases 612 toward the heat conductive airflow obstructions 548 of the heat exchange structure 542. The medial section 404 may include a baffle extending within the medial section 404 and positioned to direct the combustion gases 612 toward the plurality of respective outlets 558 corresponding to the plurality of condensing tubes 140 of the downstream section 402. In this manner, the upper heat exchange surface 304, the lower heat exchange surface 306, the transition 1040, and the heat conductive airflow obstructions 548 cooperatively define a portion of the airflow path 524 for the combustion gases 612 from the inlet 302 to the respective outlets 558 of the medial section 404.

In an exemplary embodiment, the thermal efficiency of the water heater 100 described herein is at least 95%. For example, the thermal efficiency (TE) is at least 95% at 400,000 BTU/hr. In another example, the TE is at least 97% at 200,000 BTU/hr.

Additionally, or optionally, the pressure drop of the combustion gases 612 in the heat exchanger 130 is reduced. In an exemplary aspect of the device, the pressure drop of the combustion gases 612 is reduced by up to approximately 20% to approximately 25% or more as compared to conventional heat exchangers with comparable or conventional spiral coil heat exchangers. In one non-limiting example, the pressure drop can be reduced to be under a certain number of inches (e.g., approximately 4 inches or less), although other pressure drops are contemplated. In another non-limiting example, the pressure drop can be reduced by a range of approximately 20% to approximately 25% relative to conventional water heaters that do not include the single-pass heat exchanger described herein, including but not limited to, a conventional gas side pressure drop for a typical spiral coil heat exchanger at 200,000 BTU/hr. (Natural Gas), which is approximately 5.5 in. w.c.

To achieve these efficiency parameters, heat exchanger 130 is configured to obtain a desired flow of combustion gases 612 through heat exchanger 130 that promotes high transfer of heat 514 between the combustion gases 612 and the water 530 stored in water storage tank 110 and/or promotes stratification within the water storage tank 110 for isolating condensation formation in sections of heat exchanger 130 from where condensation is undesirable, as described herein.

Referring again to FIGS. 1-31, during an exemplary operation of the water heater 100, the cold water inlet 160 of water storage tank 110 delivers unheated water 530 into water storage tank 110. The gas-fired burner 150 is configured to generate combustion gases 612 for delivery into the single-pass heat exchanger 130, particularly into the flue tube 132 as directed by the blower 170 for the transfer of heat 514 from the combustion gases 612 to water 530 in the water storage tank 110. To facilitate this transfer of heat 514 from the combustion gases 612 to water 530 in the water storage tank 110, heat conductive airflow obstructions 548, such as the flue set 574 of heat exchange fins 138, are thermally coupled to the flue tube 132 to supplement the transfer of heat 514 from the combustion gases 612 to water 530 in the water storage tank 110.

The inlet 302 of the medial section 404 receives the combustion gases 612 from the upstream section 400 and the respective outlets 558 of the medial section 404 deliver the now cooled combustion gases 612 to the downstream section 402. Heat conductive airflow obstructions 548 of the heat exchange structure 542 are thermally coupled to the upper heat exchange surface 304 to supplement the transfer of heat 514 from the combustion gases 612 to water 530 in the water storage tank 110. The condensing tubes 140 of the downstream section 402 receive the cooled combustion gases 612 from the respective outlets 558 which correspond to the condensing tubes 140. In this manner, the condensing tubes 140 are configured for transferring additional amounts of heat 514 from the cooled combustion gases 612 to water 530 in the water storage tank 110, as described herein.

The condensing set 576 of heat conductive airflow obstructions 548 are thermally coupled within the condensing tubes 140 to supplement the transfer of heat 514 from the combustion gases 612 to water 530 in the water storage tank 110. The heat conductive airflow obstructions 548 positioned along the airflow path 524 may be affixed to the flue tube 132, the condensing tubes 140, and the upper heat exchange surface 304, respectively, by way of any suitable means, such as, e.g., mechanical means including welding, binding, treading, riveting, etc., and non-mechanical means, such as, heat-resistive adhesives or the like.

In one embodiment, the heat conductive airflow obstructions 548 can be integrally formed in the flue tube 132, the upper heat exchange surface 304, or the condensing tubes 140. It is also contemplated that the heat conductive airflow obstructions 548 can be fin strips that can be welded, attached or otherwise affixed to interior surfaces of the flue tube 132, the condensing tubes 140, and/or the upper heat exchange surface 304, respectively. An end portion 148 extending from the condensing tubes 140 exits water storage tank 110 through a bottom surface of the water storage tank 110.

Referring again to FIGS. 1-31, reference numeral 130 generally refers to a heat exchanger that is incorporated within a water heating appliance 512, such as a condensing water heater 100. The heat exchanger 130 receives heat 514 from a heater 516, typically in the form of a combustion source 518, such as a gas burner 150. The heat exchanger 130 allows heated air 520, in the form of process air 522 or combustion gases 612, to pass therethrough via the airflow path 524. Heat conductive structures 526 within the heat exchanger 130 receive this heat 514 and transfer the heat 514 from the heat conductive structures 526 to the outer surface 528 of the heat exchanger 130. A fluid media, typically in the form of water 530, in turn, receives heat 514 from the outer surface 528 of the heat exchanger 130 to increase the temperature of the water 530 within a reservoir 532, also referred to herein as a water storage tank 110. According to the various aspects of the device, a heating system 534 for a water heating appliance 512 includes a heater 516 for heating the process air 522 to define heated process air 910. A blower 170 operates for delivering the process air 522 through an airflow path 524. A flue tube 132 defines an upstream section 400 of the airflow path 524 within the water heating appliance 512. A heat exchange structure 542 is disposed downstream of the flue tube 132 and defines a medial section 404 of the airflow path 524. The heat exchange structure 542 includes a heat exchange portion 912 having airflow obstructions 548. These airflow obstructions 548 absorb heat 514 from the heated process air 910 and transfer this heat 514 into the media surrounding the outer surface 528 of the heat exchange structure 542. As described herein, this media is typically in the form of water 530 to be heated within the water heating appliance 512. A diverter plate 556 is disposed below the heat exchange portion 912 of the heat exchange structure 542. This diverter plate 556 receives condensate 630 that accumulates within the heat exchange structure 542 during operation of the water heating appliance 512. A condensing section 552 of the heat exchanger 130 is disposed below the diverter plate 556 and defines a downstream section 402 of the airflow path 524. The condensing section 552 is disposed downstream of the heat exchange structure 542.

Referring to FIGS. 6-29, the airflow obstructions 548 are typically in the form of heat exchange fins 138 that are attached to an outer structure of the heat exchanger 130, such as an outer wall 572. In this manner, these airflow obstructions 548 interact with the heated process air 910. The airflow obstructions 548, being thermally conductive, absorb heat 514 from the process air 522 and transfer this heat 514 to the outer wall 572 of the heat exchanger 130. Accordingly, the outer wall 572 of the heat exchanger 130 increases in temperature due to the transfer of heat 514 from the process air 522, through the airflow obstructions 548. It is contemplated that the airflow obstructions 548 can be defined within each section of the heat exchanger 130. Accordingly, a flue set 574 of heat exchange fins 138 can be defined within the flue tube 132. Heat exchange fins 138 within the heat exchange structure 542, which can also be referred to as a finned dome or finned heat exchange structure, can be used to produce a generally outward and cyclonic motion 660 of the process air 522 to extend the residency of the process air 522 within the heat exchange structure 542, as will be described more fully herein. A condensing set 576 of heat exchange fins 138 can also be defined within the condensing section 552 of the heat exchanger 130. Each of these sections of heat exchange fins 138 operate to extract heat 514 from the process air 522 to heat the water 530 within the reservoir 532.

As exemplified in FIGS. 1-31, the density of heat exchange fins 138 may increase as the process air 522 moves downstream within the heat exchanger 130. This configuration of the heat exchange fins 138 is intended to increase the transfer of heat 514 as the process air 522 moves downstream within the airflow path 524. Accordingly, the heat exchange structure 542 and the condensing section 552 of the heat exchanger 130 typically include more heat exchange fins 138. As greater amounts of heat 514 are extracted from the process air 522 within the medial section 404 and the downstream sections 402 of the heat exchanger 130, greater amounts of heat 514 are thereby transferred into the reservoir 532. Due to the placement of the heat exchange fins 138 within the heat exchange structure 542, it is intended that greater amounts of heat 514 are extracted within the medial section 404 and the downstream section 402 of the heat exchanger 130.

As this water 530 within the medial section 404 and the downstream section 402 of the water heating appliance 512 increases in temperature, it increases in temperature at a faster rate than the water 530 within the upstream section 400 of the water heating appliance 512. Therefore, as shown in detail in FIGS. 25-26, the heated water 590, through fluid convection 594, moves upward within the reservoir 532. Contemporaneously, the lower temperature water within the upstream section 400 of the water heating appliance 512 tends to flow downward as this cooler water 592 tends to have a greater fluid density. Through this process of convection 594, the water 530 within the reservoir 532 naturally flows in a generally vertical direction between the upstream section 400 of the heat exchanger 130 and the downstream section 402 of the heat exchanger 130. Through this mechanism, water 530 within the reservoir 532 having different temperatures is mixed. As a consequence, this water 530 is thoroughly and evenly heated to allow large amounts of water 530 to be heated within the water heating appliance 512.

The water heating appliance 512 described herein is typically used for commercial and industrial applications. It is contemplated that this water heating appliance 512 can be used for larger residential applications or residential applications of various sizes.

Referring again to FIGS. 1-8, the water heating appliance 512 includes the reservoir 532 that stores water 530 to be heated. The water heating appliance 512 includes a combustion chamber 150 that is positioned upstream of the airflow path 524. The heat exchanger 130 contains the airflow path 524 and receives combustion gases 612, in the form of heated process air 910, from the combustion chamber 150. As described herein, delivery of the heated process air 910 through the airflow path 524 engages the heat exchange fins 138 and, as a result, transfers heat 514 from the process air 522 to the water 530 stored within the reservoir 532.

The heat exchanger 130 includes a single flue tube 132 that defines an upstream section 400 of the airflow path 524 for receiving the heated process air 910 from the combustion chamber 150. The flue set 574 of heat exchange fins 138 defined within the flue tube 132 transfers a portion of the heat 514 from the process air 522 into the water 530 surrounding the flue tube 132. Downstream of and below the flue tube 132, the heat exchanger 130 includes the heat exchange structure 542. This heat exchange structure 542 generally transfers heat 514 without producing condensate 630, or only small amounts of condensate 630, within the airflow path 524. This heat exchange structure 542 is attached to the flue tube 132 via a flue adapter 632 positioned within a top surface 788 of the outer wall 572 for the heat exchange structure 542. The heat exchange structure 542 includes a resistive section 638 that includes a plurality of obstructive heat exchange fins 138. Below the resistive section 638 of the heat exchange structure 542 is the condensing region 640 that is coupled to a restrictor plate 310 of the heat exchange structure 542. This condensing region 640 can include the plurality of condensing tubes 140 that extend downward from the heat exchange structure 542.

As exemplified in FIGS. 1-8, the heat exchanger 130 receives the process air 522 from the blower 170 and moves the process air 522 through the airflow path 524 in a single-pass configuration. Accordingly, the process air 522 is not recycled through the heat exchanger 130, but rather proceeds through the airflow path 524 in a sequential and non-repeating fashion. In this manner, use of the heat exchange fins 138 within the heat exchanger 130 captures a substantial amount of the heat 514 within the heat exchanger 130 for thermal transfer to the water 530 surrounding the heat exchanger 130. This creates a highly efficient heat exchanger 130 while only moving the process air 522 through the heat exchanger 130 in a single pass.

As the thermal efficiency of the heat exchanger 130 increases, this increased efficiency produces condensate 630 from the water vapor contained within the combustion gases 612 that form the process air 522. Upon the burning of a mixture of air and fuel, water 530, in the form of vapor, is formed as a constituent of the products of combustion. As this process air 522 from the combustion chamber 150 moves through the airflow path 524 and heat 514 is absorbed by the heat exchange fins 138, the temperature of the process air 522 decreases. As additional amounts of heat 514 are extracted from the process air 522 and transferred through the outer wall 572 of the heat exchanger 130 and into the water 530 of the reservoir 532, the water vapor within the combustion air tends to precipitate as condensate 630 in greater quantities. Typically, this condensate 630 is formed in the condensing region 640 of the heat exchanger 130.

As exemplified in FIGS. 9-29, greater densities and numbers of heat exchange fins 138 can be present within the heat exchange structure 542 and within the plurality of condensing tubes 140 present within the medial section 404 and downstream section 402 of the airflow path 524, respectively. Because of this, it is typical that greater condensation occurs within the plurality of condensing tubes 140, which are positioned above a condensate collector 180 of the water heating appliance 512. Stated another way, as heat 514 is absorbed by the heat exchange fins 138 and the temperature of the process air 522 decreases to be below a dew point of this process air 522, greater quantities of condensate 630 are formed from this process air 522. Because the last temperature decrease of the process air 522 occurs within the condensing tubes 140 of the condensing region 640, this is typically where the temperature of the process air 522 will fall below the dew point. Accordingly, condensate 630 is primarily formed in this condensing region 640. As a result, this condensate 630 is captured within the condensate collector 180 so that it can be drained from the heat exchanger 130 and the water heating appliance 512. To accomplish the expulsion of the captured condensate 630, the condensate collector 180 includes a fluid path that directs this condensate 630 to a drain or other external collection area of the water heating appliance 512.

In order to maximize the heat exchange between the process air 522 and the water 530 within the reservoir 532, the heat exchange fins 138 are positioned in a particular configuration to maintain a higher residency of the process air 522 within the heat exchange structure 542. To this end, the heat exchange fins 138 are positioned to generate turbulence and restrict the flow of the process air 522 to maintain a greater residency of the process air 522 within the airflow path 524. In particular, greater residency is desired within the heat exchange structure 542. Accordingly, the heat exchange fins 138 within the resistive section 638 of the heat exchange structure 542 are positioned to direct the process air 522 in the outward and cyclonic motion 660 toward an outer perimeter 662 of the heat exchange structure 542.

Referring again to FIGS. 1-8, the water heating appliance 512 includes an outer wall 572 that surrounds the reservoir 532 of the water heating appliance 512. The heat exchanger 130 is positioned within the reservoir 532. Accordingly, the airflow path 524 extends through the heat exchanger 130 and, consequently, through the reservoir 532 of the water heating appliance 512. The water heating appliance 512 includes a mechanical section 680 that is typically located at a top region 102 of the water heating appliance 512. This mechanical section 680 can be used to house the combustion chamber 150 and the blower 170. This mechanical section 680 can be positioned above the reservoir 532 or, in certain aspects of the device, adjacent to the reservoir 532.

Referring again to FIGS. 1-31, the water heating appliance 512 includes an outer housing 702 that defines the fluid reservoir 532 therein. The blower 170 is attached to the outer housing 702 and delivers process air 522 through an airflow path 524 that extends through, and is in thermal communication with, the reservoir 532. A heater 516 is attached to the outer housing 702 and operates to increase the temperature of the process air 522. The flue tube 132 is disposed within a top region 102 of the outer housing 702 and defines an upstream section 400 of the airflow path 524. The heat exchange structure 542 is attached to an end 704 of the flue tube 132 and defines a medial section 404 of the airflow path 524. The heat exchange structure 542 includes the resistive section 638 having a plurality of heat exchange fins 138 that direct the process air 522 in a cyclonic motion 660 through the plurality of heat exchange fins 138 and between the flue tube 132 and a perimeter outlet 706 of the heat exchange structure 542. The plurality of heat exchange fins 138 transfers heat 514 from the process air 522 and into the water 530 within the fluid reservoir 532. The condensing section 552 is attached to the perimeter outlet 706 of the heat exchange structure 542, typically through the use of an air diverter plate 556. The condensing section 552 defines a downstream section 402 of the airflow path 524.

Referring again to FIGS. 4-29, the heat exchange structure 542 includes the restrictor plate 310 that defines a boundary between the resistive section 638 and the condensing region 640 of the heat exchange structure 542. This restrictor plate 310 directs the process air 522 from a non-condensing resistive section 638 of the heat exchange structure 542 and to the condensing region 640 of the heat exchange structure 542.

Within this resistive section 638, the heat exchange fins 138 can extend between the outer wall 572 and the restrictor plate 310. As the process air 522 moves through this resistive section 638, the positioning of the heat exchange fins 138 causes the process air 522 to be redirected in a generally outwardly cyclonic motion 660 through the plurality of heat exchange fins 138. As described herein, this configuration of the heat exchange fins 138 provides a greater residency of the process air 522 within the resistive section 638. In other words, the process air 522 resides and moves through the heat exchange fins 138 for an extended period of time. Accordingly, greater amounts of heat 514 can be transferred to the water 530 within the reservoir 532 via the heat exchange fins 138 and the outer surface 528 of the heat exchanger 130. In certain aspects of the device, an inner wall 980 can be positioned on the restrictor plate 310. In such an aspect of the device, the resistive section 638 can be defined between the outer wall 572 and the inner wall 980. The restrictor plate 310 can be positioned below the inner wall 980 and can extend outward to the perimeter outlets 706 that direct the process air 522 from the resistive section 638 to the condensing region 640 of the heat exchange structure 542.

As exemplified in FIGS. 7-29, the plurality of heat exchange fins 138 within the resistive section 638 of the heat exchange structure 542 are typically positioned within concentric rings 730 that extend outward from the flue adapter 632 and to the perimeter outlets 706 defined by the restrictor plate 310. Each of these concentric rings 730 of heat exchange fins 138 includes individual heat exchange fins 138 that are positioned at an angle with respect to a circle 732 that extends through each of the heat exchange fins 138 within a particular concentric ring 730. Accordingly, the angular positioning of the heat exchange fins 138 deflects the flow of the process air 522 toward a residency space 734 that is defined between adjacent concentric rings 730. The angle of the heat exchange fins 138 is designed to cause the process air 522 to reside within the residency space 734 for a period of time before passing through the next concentric ring 730 of heat exchange fins 138 and into the next residency space 734. It is this movement of the process air 522 that results in the outwardly cyclonic motion 660 of the process air 522 within the heat exchange structure 542.

Within the heat exchange fins 138 of each concentric ring 730 and between these concentric rings 730, various turbulence flows 750 are created that maintain the process air 522 within the resistive section 638 of the heat exchange structure 542. This phenomenon creates greater residency of the process air 522 within the resistive section 638 of the heat exchange structure 542. Accordingly, the various flows of process air 522 that move through the resistive section 638 of the heat exchange structure 542 engage many of the heat exchange fins 138. Each of these heat exchange fins 138 absorbs at least a portion of the heat 514 from the process air 522 and transfers this heat 514 through the outer wall 572 of the heat exchange structure 542, and into the water 530 of the reservoir 532 for the water heating appliance 512.

Referring to FIGS. 9-13, in certain aspects of the device, each of the heat exchange fins 138 can be welded, individually, to the underside 760 of the outer wall 572 of the heat exchange structure 542. As exemplified in FIG. 12, each of these heat exchange fins 138 can be set within a recess 762 defined within the outer wall 572 for the heat exchange structure 542. Accordingly, positioning recesses 762 for each of the heat exchange fins 138 can be defined within the underside 760 of the outer wall 572. As exemplified in FIG. 13, each of the heat exchange fins 138 can be welded to the underside 760 of the outer wall 572, without the need for the positioning recesses 762. In each of these instances, the heat exchange fins 138 are welded, adhered, soldered, or otherwise attached to the underside 760 of the outer wall 572 of the heat exchange structure 542.

As exemplified in FIGS. 4, 6, and 9-17, the heat exchange fins 138 can be welded at a top edge 780 to the underside 760 of the outer wall 572 for the heat exchange structure 542. The bottom edge 782 of each of the heat exchange fins 138 may be set apart from the inner wall 980 or the restrictor plate 310 or may be positioned in a close engagement or surface-to-surface engagement with respect to the inner wall 980 or the restrictor plate 310. Through this configuration, small amounts of condensate 630 that may be produced during operation of the water heating appliance 512 can flow along the convex curvature 784 of the inner wall 980 or the surface of the restrictor plate 310 and under the bottom edges 782 of the various heat exchange fins 138. To assist in moving amounts of condensate 630 that may be produced within the resistive section 638 of the heat exchange structure 542, fluid channels 786 can be defined within the top surface 788 of the inner wall 980 or the restrictor plate 310 to promote the movement of condensate 630 toward and through the perimeter outlets 706 of the restrictor plate 310 and onto the condensing region 640 of the heat exchange structure 542.

According to the various aspects of the device, the various heat exchange fins 138 can have a generally rectangular configuration. It is also contemplated that the heat exchange fins 138 can include various angled or curved surfaces that promote a desired level of turbulence as the process air 522 moves through the plurality of heat exchange fins 138 in the resistive section 638. By creating a desired level of turbulence, the desired residency of the process air 522 within the resistive section 638 of the heat exchange structure 542 can be achieved. Extending the residency of the process air 522 within the resistive section 638 of the heat exchange structure 542 has the effect of extracting additional amounts of heat 514 from the process air 522 and transferring this heat 514 into the water 530 of the reservoir 532. Typically, the desired level of turbulence and residency will result in the temperature of the process air 522 nearing, but not falling below, the dew point of the process air 522. As described herein, it is desired that the temperature of the process air 522 falls below the dew point within the condensing region 640 of the heat exchange structure 542 and within the condensing tubes 140.

Referring now to FIGS. 14-18, the heat exchange fins 138 can be positioned within concentric rings 730 that are positioned successively outward from the flue adapter 632 and to the perimeter openings of the restrictor plate 310. Each of these concentric rings 730 of heat exchange fins 138 can be set within a frame 790. Each of these frames 790 are typically positioned concentrically with respect to one another and can be shaped to generally match the shape of the heat exchange structure 542. The various heat exchange fins 138 can be attached to the frames 790 or can be cut out from the frames 790 and bent at an angle with respect to the various circular frames 790 of the heat exchange structure 542. The frames 790 are typically circular in shape. Additionally, the frames 790 can include an upper member 792 that is attached, typically through welding, to the underside 760 of the outer wall 572 for the heat exchange structure 542. The lower member 794 of the circular frame 790 is typically within a close engagement with the top surface 788 of the inner wall 980 or the restrictor plate 310 or a surface-to-surface engagement with this top surface 788. The various heat exchange fins 138 are then positioned between the upper member 792 and the lower member 794 of the circular frames 790 at an angle to promote the turbulence of the process air 522 within the resistive section 638 of the heat exchange structure 542.

As discussed herein, each of these heat exchange fins 138 can be cut out from a generally cylindrical ring. When each of the heat exchange fins 138 are bent inward or outward with respect to the circular frame 790, the upper member 792 and the lower member 794 of the circular frames 790 are formed. Additionally, various vertical supports 810 can be formed between the individual heat exchange fins 138 of each circular frame 790. In certain aspects of the device, the vertical supports 810 form a connection point, typically in the form of a bending portion 812, of each of the heat exchange fins 138. This bending portion 812 extends between the upper member 792 and the lower member 794 of the circular frames 790. The various heat exchange fins 138 extend at an oblique angle with respect to these bending portions 812 to form the angular configuration of the plurality of heat exchange fins 138.

As exemplified in FIGS. 16-29, it is contemplated that the inner wall 980 can be attached to the lower member 794 of the circular frames 790. In this configuration, the inner wall 980 can be suspended from the circular frames 790. Accordingly, the outer edge of the restrictor plate 310 forms the plurality of perimeter openings, or a singular outer opening that extends around the restrictor plate 310.

Referring again to FIGS. 4-29, the various heat exchange fins 138 are made from a metallic material having good thermal conductivity. Typically, the innermost concentric ring 730 proximate the flue adapter 632 is made of stainless steel or other non-corrosive metal. This material choice is intended to prevent corrosion of this innermost concentric ring 730 and the respective set of heat exchange fins 138. The outer concentric rings 730 of the heat exchange fins 138 can be made of stainless steel, carbon steel, various steel alloys, or other materials having good thermal conductivity.

According to the various aspects of the device, as exemplified in FIGS. 1-31, the positioning of the heat exchange fins 138 is designed to maintain a generally consistent air pressure within the resistive section 638 of the heat exchange structure 542. In doing so, the process air 522 moving through this resistive section 638 tends to not experience a significant drop in air pressure as it moves between the various heat exchange fins 138. Preventing this air pressure drop is important to prevent the process air 522 from moving too quickly through the resistive area of the heat exchange structure 542. A decrease in pressure of the process air 522 typically results in an increase in velocity of this pressure air as it moves between the plurality of heat exchange fins 138. Accordingly, the angular configuration and spacing of the heat exchange fins 138 within the resistive section 638 of the heat exchange structure 542 is designed to prevent this pressure drop to maintain an efficient transfer of heat 514 from the process air 522, through the heat exchange fins 138, and into the water 530 of the reservoir 532.

A bottom wall of the heat exchange structure 542 includes a diverter plate 556 that diverts the process air 522 moving through the heat exchange structure 542 into the plurality of flue tubes 132 that extend downward from the heat exchange structure 542. Within these plurality of flue tubes 132, the temperature of the combustion gases 612 typically drops between the dew point of the process air 522 such that larger amounts of condensate 630 are produced within these flue tubes 132. As described herein, a condensate collector 180 is positioned below the flue tubes 132 and within a bottom section of the water heating appliance 512. This condensate collector 180 collects the condensate 630 that is formed through the various portions of the airflow path 524 and allows for the movement of this condensate 630 to a drain or other area external to the water heating appliance 512. The condensate collector 180 also includes air exhaust spaces 816 connected to an exhaust outlet 818. Accordingly, the exhaust gases from the water heating appliance 512 can be delivered to an area outside of the structure housing the water heating appliance 512 via the exhaust outlet 818. Additionally, the appliance 512 can include a condensate outlet 820 that delivers the captured condensate 630 from the condensate collector 180 and delivers the condensate 630 to an external drain..

According to the various aspects of the device, an exemplary embodiment of the heat exchanger 130 having the heat exchange structure 542 has a thermal efficiency of at least approximately 95 percent. By way of example, and not limitation, a thermal efficiency of the exemplary heat exchanger is at least approximately 95 percent at 400,000 BTU/hr. In another example, the thermal efficiency can be at least approximately 97 percent at 200,000 BTU/hr. The pressure drop of the combustion gases 612 within the heat exchanger 130 can be reduced when compared with conventional heat exchangers. In at least one non-limiting example, the pressure drop can be reduced to be under a certain number of inches, such as about 4 inches or less. In another non-limiting example, the pressure drop can be reduced to a range of from approximately 20 percent to approximately 25 percent relative to a conventional water heater that does not include a single-pass heat exchanger, as described herein. Accordingly, the single-pass heat exchanger described herein has been shown to be more efficient than conventional spiral coil heat exchangers. Therefore, greater efficiencies can be achieved in thermal transfer through the use of the single-pass heat exchanger described herein.

Referring again to FIGS. 1-31, the heat exchange structure 542 for the water heating appliance 512 can include a convex outer wall 572 that defines a central inlet or a flue adapter 632. An interior wall, typically in the form of the inner wall 980, opposes the convex upper wall and defines a heat exchange cavity therebetween for the resistive section 638. The inner wall 980 in combination with the restrictor plate 310 defines the perimeter outlets 706.

In certain aspects of the device, the inner wall 980 and the restrictor plate 310 can be a single integral member that extends across the heat exchange structure 542. It is also contemplated that the inner wall 980 and the restrictor plate 310 can be separate components. In such an aspect of the device, the inner wall 980 can rest upon the restrictor plate 310 and the perimeter outlets 706 are disposed around the outer edge of the restrictor plate 310 of the heat exchange structure 542. A plurality of heat exchange fins 138 extends between the convex outer wall 572 and the interior wall or inner wall 980. The plurality of heat exchange fins 138 directs the process air 522 in a generally cyclonic motion 660 from the flue adapter 632, through the plurality of heat exchange fins 138, and to the perimeter outlets 706 of the restrictor plate 310. Using this configuration of the heat exchange fins 138, the heat exchange structure 542 defines a large surface area against which the process air 522 engages to transfer heat 514 from the process air 522, through the heat exchange fins 138, and to the water 530 of the reservoir 532 that surrounds the heat exchanger. A lower wall, typically in the form of the air diverter plate 556, is positioned below the restrictor plate 310 to define a condensing region 640. The plurality of flue tubes 132 extends downward from this air diverter plate 556.

Referring again to FIGS. 1-8, the heat exchange structure 542 can be positioned within the reservoir 532, typically approximately halfway down from a top portion 112 of the reservoir 532 or approximately two-thirds down from the top portion 112 of the reservoir 532. Various other positions are contemplated of the heat exchange structure 542 within the reservoir 532.

According to the various aspects of the device, the plurality of heat exchange fins 138 within the resistive area of the heat exchange structure 542 can be positioned in any one of various configurations. Typically, the concentric rings 730 of heat exchange fins 138 are evenly spaced between the flue adapter 632 and the perimeter outlets 706 of the restrictor plate 310. It is also contemplated that the spacing of these concentric rings 730 of heat exchange fins 138 can vary to maintain the air pressure of the process air 522 as it moves through the resistive area of the heat exchange structure 542. Additionally, the size of the fins can vary within the resistive area. Accordingly, the shape of the outer wall 572 and the shape of the inner wall 980 may have separate convex curvatures 784 such that the resistive area can increase in height or decrease in height as the process air 522 moves from the flue adapter 632 to the perimeter outlets 706 of the restrictor plate 310. Again, this configuration of the various heat exchange fins 138 is intended to maintain the air pressure of the process air 522 as it moves to the resistive area and to prevent pressure drop of the process air 522.

Referring again to FIGS. 14-29, the bending portion 812 of the circular frames 790, from which the heat exchange fins 138 extend, can be used to bend the heat exchange fins 138 inward toward the flue adapter 632 or outward toward the perimeter outlets 706. Typically, the heat exchange fins 138 will bend in the same direction. However, it is also contemplated that changes in the way that the heat exchange fins 138 extend from the bending portion 812 can vary between the various concentric rings 730.

Referring now to FIGS. 19-29, the heat exchange structure 542 includes a plurality of circular frames 790 that form the concentric rings 730 of heat exchange fins 138 for the heat exchange structure 542. Each of these circular frames 790 are positioned concentrically with respect to one another, and typically with respect to the flue adapter 632. The various heat exchange fins 138 can be attached to the circular frames 790 and can be cut out from the frames 790. The heat exchange fins 138 can then be bent at an angle with respect to the various circular frames 790 of the heat exchange structure 542. The formation, positioning, material, and manipulation of the heat exchange fins 138 are similar to that of other aspects of the device that include the circular frames 790.

Typically, as described herein, the circular frames 790 can include an upper member 792 that is attached to the underside 760 of the outer wall 572 for the heat exchange structure 542. The circular frames 790 can also include a lower member 794. Each lower member 794 can include a bottom flange 850 that is positioned at an angle with respect to the upper member 792 and the vertical supports 810 for each circular frame 790. Typically, this bottom flange 850 will extend from a respective circular frame 790 to an inner-facing surface 852 of an adjacent circular frame 790. Through this configuration, the bottom flanges 850 can be attached to an adjacent circular frame 790 through welding, adhesives, or other attachment mechanism or method. The bottom flanges 850 can be integral with the lower member 794, or can be attached to the lower member 794 through adhesives or welding. Typically, the bottom flanges 850 are defined by bent portions of the respective lower members 794 for the circular frames 790.

Referring still to FIGS. 19-29, through the use of these bottom flanges 850 of the circular frames 790, the various bottom flanges 850 can form an integral shell 860 that defines a lower boundary 862 of the resistive section 638 for the heat exchange structure 542. Through the use of the bottom flanges 850, the inner wall 980 can be attached to the inner-facing surface 852 of the innermost circular frame 864 and positioned below the flue adapter 632. Accordingly, the inner wall 980 can extend across the space defined by the innermost circular frame 864 to enclose the resistive section 638 of the heat exchange structure 542.

As described herein, each of the heat exchange fins 138 can be cut out from a cylindrical ring that forms the circular frames 790. Each cylindrical ring can include the bottom flange 850 that is bent, attached, or otherwise formed to a position that is perpendicular or substantially perpendicular to the vertical supports 810 for the circular frame 790. It should be understood that “perpendicular or substantially perpendicular” is meant to describe and include angles that are within approximately 30 degrees of perpendicular with respect to the vertical supports 810 for the circular frame 790. Additionally, “perpendicular or substantially perpendicular” can also refer to a configuration of the bottom flanges 850 that follow the convex shape of the inner wall 980.

Referring still to FIGS. 19-29, the vertical supports 810, as described herein, are positioned between the angled heat exchange fins 138. In certain aspects of the device, the vertical supports 810 can also define the bending portions 812 for the various heat exchange fins 138. In such an aspect of the device, the various heat exchange fins 138 are cut or punched out from the cylindrical body that forms the circular frame 790 and bent along the bending portions 812 in a certain orientation with respect to the circular frames 790 to define the heat exchange fins 138.

Use of the circular frames 790 having the bottom flanges 850 that form the integral shell 860 can be utilized for minimizing the need for an additional inner wall 980 that extends across the entire resistive section 638 of the heat exchange structure 542. Additionally, use of the bottom flanges 850 of the various circular frames 790 provides a different manufacturing method and assembly for forming the lower boundary 862 of the resistive section 638.

By way of example and not limitation, using the bottom flanges 850 of the circular frames 790, the integral shell 860 can be formed progressively as each of the circular frames 790 is installed to the outer wall 572 of the heat exchange structure 542. As each circular frame 790 is installed to the outer wall 572, the bottom flange 850 for the outermost circular frame 880 can be attached to an area defining the perimeter outlet 706 of the heat exchange structure 542 that is positioned at an outer perimeter 662 of the heat exchange structure 542.

In certain aspects of the device, an outer ring 878 can be attached to the bottom flange 850 for the outermost circular frame 880 and extend to form the perimeter outlet 706. Each subsequent circular frame 790 can be attached inward of the previous circular frame 790. An outward edge 882 of each of the bottom flanges 850 can then be attached to the inner-facing surface 852 for the lower member 794 of the adjacent circular frame 790. This attachment seals the resistive section 638 to prevent the escape of process air 522 moving through the airflow path 524.

It is also contemplated that the various circular frames 790 can be manufactured or installed from the innermost circular frame 864 and progressively outward to the outermost circular frame 880 and the outer ring 878.

As described herein, and as illustrated in FIGS. 19-29, use of the circular frames 790 having an integral bottom flange 850 creates the resistive section 638 that is made up of the various heat exchange fins 138 of the circular frames 790. These heat exchange fins 138 are configured to generate the general flow of a cyclonic motion 660 of process air 522 moving through the resistive section 638. The turbulence flows of process air 522 that moves through the various residency spaces of the resistive section 638 causes heat to be transferred from the process air 522 to the heat exchange fins 138 and into the water surrounding the outer surface 528 of the heat exchanger 130.

Referring again to FIGS. 1-31, during operation of the appliance 512, the condensing function of the heat exchanger 130 operates to gradually and thoroughly cool the process air 522 that is received from the combustion chamber 150. Typically, the temperature of the process air 522 within the resistive section 638 of the heat exchange structure 542 will be maintained above the dew point of the process air 522. Accordingly, the condensate 630 produced within this area is kept to a minimum. As the process air 522 moves to the air diverter plate 556 and into the plurality of condensing tubes 140, greater amounts of heat can be exchanged from the process air 522 and into the water 530. Accordingly, the process air 522 is cooled below the dew point and greater amounts of condensate 630 can be collected within these areas. Condensate 630 that is precipitated within the airflow path 524 can be collected within the air diverter plate 556. It is contemplated that this condensate 630 can travel through the plurality of condensing tubes 140 to the condensate collector 180. It is also contemplated that dedicated condensate drains 830 (shown in FIG. 8) can be defined within the air diverter plate 556 such that this condensate 630 can travel through dedicated pathways to the condensate collector 180. Accordingly, the process air 522 can move through separate channels from the condensate drains 830 to maintain the efficiency of heat exchange from the process air 522 through the various fins 138 of the heat exchanger 130.

Referring still to FIGS. 1-31, the heating system 534 for the water heating appliance 512 includes the heater 516 for generating heated process air 910. As discussed herein, this heated process air 910 is typically in the form of a combustion gas 612 that is created through the burning of fuel, such as natural gas. The heated process air 910 can also be generated through an electrical heater, such as an electrically resistive element, or other similar heating system. A blower 170 is included in the heating system 534 for delivering the heated process air 910 through the airflow path 524. Coupled to the heater 516 and the blower 170 are a flue tube 132 that defines an upstream section 400 of the airflow path 524. A heat exchange structure 542 is disposed downstream of the flue tube 132 and defines a medial section 404 of the airflow path 524. The heat exchange structure 542 includes a heat exchange portion 912 having airflow obstructions 548 that generate turbulence within the heated process air 910. Through the use of this turbulence within the heated process air 910, a greater and more thorough transfer of heat from the heated process air 910 to the media surrounding the outer surface 528 of the heat exchange structure 542 is accomplished. The airflow path 524 within the heat exchange portion 912 extends outward and generally perpendicular to a central axis 914 of the airflow path 524 within the flue tube 132.

As discussed herein, the heat exchange portion 912 of the heat exchange structure 542 redirects the heated process air 910 from the flue tube 132 to move through the airflow obstructions 548. Using the airflow obstructions 548 and the turbulence generated thereby, the heated process air 910 has a longer residency within the heat exchange portion 912. In this manner, greater amounts of heat can be extracted from the heated process air 910 for delivery into the media surrounding the heat exchange structure 542. The condensing section 552 defines the downstream section 402 of the airflow path 524. This condensing section 552 is disposed downstream of the heat exchange structure 542. Accordingly, the flue tube 132 and the heat exchange structure 542 define a sensible heat exchange area 930. The condensing section 552 defines a latent heat exchange area 932 that causes a condensation of humidity within the heated process air 910. The heated process air 910 transitions to cooled process air 934 as the heated process air 910 moves through the flue tube 132 and the heat exchange structure 542 that make up the sensible heat exchange area 930. This cooled process air 934 is then delivered to the condensing section 552. Within the condensing section 552, as discussed herein, additional heat 514 is extracted therefrom. This additional cooling cause humidity to condense from the process air 522, thereby generating dehumidified process air 936 within the latent heat exchange area 932.

The terms “upstream section,” “medial section,” and “downstream section” that are used in relation to the water heating appliance 512 refer to the sequential progression of process air 522 as the process air 522 moves through the airflow path 524. These terms do not necessarily relate to the orientation of these sections within the appliance. It is contemplated that the orientation of the upstream section 400, the medial section 404, and the downstream section 402 may be positioned along a wide range of directional orientations. By way of example, and not limitation, the upstream section 400 may be positioned above the medial section 404 and the downstream section 402. Alternatively, it is contemplated that the upstream section 400 may be positioned within a base of the appliance such that the process air 522 moves in an upward direction toward the medial section 404 and the downstream section 402 of the airflow path 524. Lateral movement of the process air 522 through the airflow path 524 is also contemplated.

Referring again to FIGS. 1-31, the airflow obstructions 548 defined within the heat exchange portion 912 of the heat exchange structure 542 typically are defined by a plurality of fins 138. Each fin 138 of the plurality of fins 138 can be positioned in an angular orientation with respect to the adjacent fins 138 of the plurality of fins 138. Accordingly, the positioning of these fins 138 or other airflow obstructions 548 generate turbulence within the heated process air 910 moving through the heat exchange structure 542. As discussed herein, the turbulence causes greater residency of the heated process air 910 within the heat exchange portion 912.

According to the various aspects of the device, the heated process air 910 moving through the heat exchange portion 912 and the airflow obstructions 548 is described as moving generally perpendicular to the direction of the airflow path 524 within the flue tube 132. It is contemplated that this movement of the heated process air 910 through the heat exchange portion 912 can be redirected at a deflecting member 950 of the heat exchange structure 542. Using this deflecting member 950, the heated process air 910 is redirected from an axial direction 952 along the central axis 914 of the flue tube 132 to an outward direction 954 that is oblique or generally perpendicular to the axial direction 952 and through the airflow obstructions 548 of the heat exchange portion 912. Accordingly, the motion of the heated process air 910 is in a generally outward direction 954 with respect to a central axis 914 of the flue tube 132.

Additionally, as described herein, and as illustrated in FIGS. 9-29, the turbulence generated by the airflow obstructions 548 within the heat exchange portion 912 causes the heated process air 910 to remain within the heat exchange portion 912. The expanded volume of the heat exchange portion 912 also provides for this greater residency of the heated process air 910 within the heat exchange portion 912. In addition, to accommodate this motion of the heated process air 910 in the outward direction 954, the heat exchange structure 542 includes the outer wall 572 that forms a generally frusto-conical shape, which can include a generally conical shape, a dome shape, a flattened disk shape, a combination of these shapes, or other similar geometry. This configuration of the heat exchange structure 542 provides for the motion of the heated process air 910 in the outward direction 954 and through the heat exchange portion 912 of the heat exchange structure 542. Also, the plurality of fins 138 that can be used to form the airflow obstructions 548, are typically attached to an inner surface 970 of the outer wall 572 of the heat exchange structure 542. Through this connection, heat 514 can be transferred via the heated process air 910, through the fins 138, and then through the outer wall 572 of the heat exchange structure 542 for transferring into the media surrounding the heat exchange structure 542.

Referring still to FIGS. 19-29, according to the various aspects of the device, the heat exchange structure 542 includes an inner wall 980 that opposes the outer wall 572. This inner wall 980 can be utilized to define a portion of the airflow path 524 between the outer wall 572 and the inner wall 980 for the heat exchange structure 542. The plurality of fins 138 typically extend from the outer wall 572 toward the inner wall 980. In certain aspects of the device, the fins 138 can engage each of the outer wall 572 and the inner wall 980 so that at least a portion of the fins 138 extend fully between the inner surface 970 of the outer wall 572 and a top surface 788 of the inner wall 980. Additionally, it is contemplated that in certain aspects of the device, the plurality of fins 138 are positioned in generally concentric rings 730 of fins 138. In such an aspect of the device, each ring 730 of fins 138 can be disposed at an angle with respect to a corresponding concentric circle 732. In this manner, the heated process air 910 moving through the plurality of fins 138 experiences turbulence that is generated by the plurality of fins 138. Also, the motion of the heated process air 910 through the plurality of fins 138 can be in a generally cyclonic motion 660 as the heated process air 910 moves in the outward direction 954. In this manner, the heated process air 910 may engage most or all of the fins 138 of each concentric circle 732 of the heat exchange structure 542. Through this configuration of the fins 138 and other airflow obstructions 548, the heated process air 910 is redirected by the fins 138 and is generally prevented from moving in a directly outward radial direction from the flue tube 132. Rather, the configuration of the heat exchange structure 542 and the plurality of fins 138 disposed therein causes the heated process air 910 to move in a circuitous path 990 through the plurality of fins 138, which may be in the form of the cyclonic motion 660 described herein. The circuitous path 990 may also be an undulating path, a sinusoidal path, an irregular path, combinations thereof, or other similar patterns of movement through the airflow obstructions 548 of the heat exchange structure 542. Using this circuitous path 990 created by the plurality of fins 138, greater amounts of heat 514 can be extracted from the heated process air 910 and transferred into the media surrounding the heat exchange structure 542.

Referring now to FIGS. 1-8 and 25-31, the condensing section 552 includes an exhaust outlet 818. In this manner, the flue tube 132, the heat exchange structure 542, and the condensing section 552 cooperate to provide a single pass condensing heat exchanger 130. This single pass condensing heat exchanger 130 allows for the motion of heated process air 910 to move continuously and sequentially through the airflow path 524. Because the water heating appliance 512 provides for a single pass of the heated process air 910, heat 514 is continuously extracted from the heated process air 910 as it moves through the airflow path 524. Ultimately, after the process air 522 leaves the condensing section 552, the now dehumidified process air 936 is expelled through the exhaust outlet 818.

During operation of the water heating appliance 512, the heated process air 910 is created by the heater 516, this heated process air 910 moves through the flue tube 132. The flue set 574 of the fins 138 that is disposed within the flue tube 132 extracts some heat 514 from the heated process air 910. The heated process air 910 is then directed into the heat exchange structure 542 where the heated process air 910 moves through the plurality of fins 138. Larger amounts of heat 514 are extracted from the plurality of fins 138 within the heat exchange structure 542. This heat 514 is directed into the media surrounding the heat exchange structure 542. Accordingly, the temperature of the heated process air 910 is greatly reduced within the heat exchange structure 542. Accordingly, cooled process air 934 is directed from the perimeter outlet 706 of the heat exchange structure 542 and into the condensing section 552 of the airflow path 524. This cooled process air 934 is typically of a temperature that is less than the heated process air 910, but still above a dewpoint of the process air 522 moving through the airflow path 524. Accordingly, while the temperature of the heated process air 910 is decreased through the plurality of fins 138 within the heat exchange structure 542, the temperature of the process air 522 is not decreased to a point where condensation of humidity within the process air 522 occurs. The cooled process air 934 is then moved into the condensing section 552. Within this condensing section 552, greater amounts of heat 514 are further extracted from the cooled process air 934. In this manner, the temperature of the process air 522 falls below the dewpoint of the process air 522. Once the temperature of the process air 522 reaches the dewpoint and moves below the dewpoint, humidity within the process air 522 is condensed and condensate 630 is produced. This condensate 630 is directed through the condensing tubes 140 of the condensing section 552 to form dehumidified process air 936 that is then directed to the exhaust outlet 818 for the appliance 512. The condensate 630 produced within the condensing section 552 is directed to a drain 830 for removal from the appliance 512.

According to the various aspects of the device, as exemplified in FIGS. 1-31, the water heating appliance 512 having the single pass condensing heat exchanger 130 includes an outer housing 1020 that defines the reservoir 532 therein for storing a fluid to be heated. The heater 516 for heating process air 522 is attached to the upstream section 400 of an airflow path 524, where the heater 516 operates to define the heated process air 910. A blower 170 is coupled to the outer housing 1020 and delivers the heated process air 910 through the airflow path 524 that extends through, and is in thermal communication with, the reservoir 532. The flue tube 132 is disposed within the outer housing 1020 and defines the upstream section 400 of the airflow path 524. The heat exchange structure 542 includes a transition 1040 in the form of the deflecting member 950 that is positioned proximate to an end 704 of the flue tube 132. The heat exchange structure 542 defines the medial section 404 of the airflow path 524. The heat exchange structure 542 includes an interior chamber 1030, which defines the heat exchange portion 912, having the plurality of airflow obstructions 548, typically in the form of the heat exchange fins 138. These heat exchange fins 138 generate turbulence within the heated process air 910 that increases a residency of the heated process air 910 within the heat exchange structure 542. The plurality of heat exchange fins 138, and other airflow obstructions 548, transfer heat 514 from the heated process air 910 to the media within the reservoir 532. As described herein, the heated process air 910 is converted to cooled process air 934 within the heat exchange structure 542. The condensing section 552 is attached to the heat exchange structure 542 and defines the downstream section 402 of the airflow path 524. The deflecting member 950 of the heat exchange structure 542 defines the transition 1040 that directs the heated process air 910 towards the airflow obstructions 548, including the heat exchange fins 138. The deflecting member 950 of the heat exchange structure 542 includes a heat-resistant material. This heat-resistant material can include ceramic, masonry, metals, a combination thereof, and other similar heat-resistive materials.

The flue tube 132 extends along the central axis 914. The heated process air 910 moves through the flue tube 132 along the central axis 914. The transition 1040 of the heat exchange structure 542 defined by the deflecting member 950 redirects the heated process air 910 to travel in a direction that is one of perpendicular to the central axis 914 and oblique to the central axis 914, as described herein. The expanded volume of the heat exchange structure 542 provides for a greater residency of the heated process air 910 within the heat exchange portion 912 of the heat exchange structure 542. Accordingly, the plurality of fins 138 and other airflow obstructions 548 provide for a greater exchange of heat 514 from the heated process air 910 and into the media surrounding the heat exchange structure 542.

The condensing section 552 of the airflow path 524 is positioned downstream of the heat exchange structure 542. The condensing section 552 includes the plurality of condensing tubes 140 that are oriented generally parallel with the central axis 914. The plurality of condensing tubes 140 directs the process air 522 from the heat exchange structure 542 to the exhaust outlet 818. As described herein, within the condensing tubes 140 of the condensing section 552, the temperature of the process air 522 is reduced through the extraction of heat 514 from the now cooled process air 934. This extraction of additional heat 514 causes the temperature of the cooled process air 934 to fall below the dewpoint of the process air 522 such that the humidity within the process air 522 undergoes a phase change from a vapor to a liquid. Through this phase change, condensate 630 is formed in the process and a significant amount of heat 514 is given off as a result of this phase change. In turn, the process air 522 becomes dehumidified process air 936 that is directed to the exhaust outlet 818.

Within this latent heat exchange area 932, the condensation of vapor to liquid condensate 630 extracts large amounts of heat 514 from the cooled process air 934. This heat 514 is directed through the condensing set 576 of fins 138 and the outer sleeve 1050 and into the media surrounding the condensing section 552 of the airflow path 524. This phase change of moisture within the process air 522 from vapor to liquid is accomplished through the single pass condensing water heating appliance 512. The single pass configuration of the water heating appliance 512 is accomplished through the cooperation of the flue tube 132, the heat exchange structure 542, and the condensing tubes 140 of the condensing section 552. Through this configuration, the process air 522 can move through the airflow path 524 in a single pass. Accordingly, the process air 522 is not redirected or recirculated through portions of the airflow path 524. Accordingly, the single pass configuration of the appliance 512 provides for efficient and highly effective extraction of heat 514 from the process air 522 as the process air 522 moves sequentially through the airflow path 524.

Referring again to FIGS. 1-31, the heating system 534 for the water heating appliance 512 includes the flue tube 132 that defines the upstream section 400 of the airflow path 524. As described herein, the flue tube 132 directs the process air 522 along the central axis 914. The air delivery system, typically in the form of a blower 170, delivers the heated process air 910 into and through the airflow path 524 via the flue tube 132. The heat exchange structure 542 is attached to an end 704 of the flue tube 132, opposite the air delivery system. The heat exchange structure 542 defines the medial section 404 of the airflow path 524. The heat exchange structure 542 includes a transition 1040, typically in the form of the deflecting member 950, that directs the heated process air 910 in the outward direction 954 from the end 704 of the flue tube 132 and in a generally perpendicular or oblique direction with respect to the central axis 914 of the flue tube 132. The heat exchange structure 542 also includes the airflow obstructions 548 that transfer heat 514 from the heated process air 910. This heat 514 is transferred from the airflow obstructions 548 and through an outer wall 572 of the heat exchange structure 542. From the outer wall 572 of the heat exchange structure 542, the heat 514 is transferred into the media, typically water, surrounding the outer surface 528 of the outer wall 572 for the heat exchange structure 542. The condensing section 552 of the airflow path 524 is attached to the heat exchange structure 542 and defines the downstream section 402 of the airflow path 524. The flue tube 132 and the heat exchange structure 542 define the sensible heat exchange area 930 and the condensing section 552 defines the latent heat exchange area 932 that causes a condensation of humidity within the process air 522. As described herein, the airflow obstructions 548 are typically defined by plurality of fins 138. Typically, each fin 138 of the plurality of fins 138 is positioned in a pattern of generally concentric circles 732. Within these concentric circles 732, each fin 138 is positioned in angular orientation with respect to adjacent fins 138 of the plurality of fins 138.

According to the various aspects of the device, the temperature of the heated process air 910 moving through the sensible heat exchange area 930 can be extremely high as it leaves the combustion area and moves through the flue tube 132. This high temperature of the heated process air 910 may affect certain components disposed within the airflow path 524. To protect these components from an accelerated heat degradation, the heated process air 910 may be allowed to move faster through certain upstream areas of the airflow path 524 to manage the transfer of heat 514 from the heated process air 910 and through the plurality of fins 138 that are disposed within the airflow path 524. Accordingly, within the heat exchange structure 542, the airflow obstructions 548 and upstream section 400 of the heat exchange structure 542 may be positioned to allow for a more expedient motion of process air 522 through the airflow obstructions 548. This expedient motion can correspond to a diminished level of turbulence and proportionally diminished residency of the heated process air 910 within portions of the heat exchange structure 542. Accordingly, at least a portion of the innermost airflow obstructions 1060 may be defined by a plurality of fins 138 that extend only partially from the inner surface 970 of the outer wall 572 and towards the inner wall 980. In this manner, the heated process air 910, having a high temperature, can move past the innermost airflow obstructions 1060 in the more expedient motion that may experience a lesser degree of turbulence.

Because the heated process air 910 within these upstream sections 400 has a high temperature, greater amounts of heat 514 are still transferred from the heated process air 910 and through the innermost airflow obstructions 1060. These innermost airflow obstructions 1060 deliver or transfer heat and, in turn, decrease the temperature of the heated process air 910 that then moves into the outer airflow obstructions 1062 which provide greater amounts of turbulence and greater amounts of residency within the heat exchange structure 542. The configuration of the innermost airflow obstructions 1060 and the outer airflow obstructions 1062 is used to balance the amount of heat 514 transferred through the airflow obstructions 548 and the amount of heat 514 that can be extracted from the heated process air 910. One of the purposes of this configuration is to prevent the airflow obstructions 548 from being heated to a temperature that meets or exceeds a degradation temperature of the material that makes up the airflow obstructions 548.

As shown in an exemplary manner in FIGS. 14-29, the configuration of the various airflow obstructions 548 is generally calibrated to provide for a generally consistent extraction of heat 514 from the heated process air 910 as it moves through the airflow obstructions 548. Accordingly, the heated process air 910 having a higher temperature may move faster through certain airflow obstructions 548 to initially decrease the temperature of the heated process air 910 from the highest temperature to a lowered temperature. The outer airflow obstructions 1062 provide for greater amounts of turbulence and longer residency of the heated process air 910 within the airflow obstructions 548 so that heat 514 can be continuously extracted from the process air 522 and transferred through the outer wall 572 of the heat exchange structure 542 for heating the media surrounding heat exchange structure 542.

In certain aspects of the device, the plurality of airflow obstructions 548 within the heat exchange structure 542 may include a gradient of turbulence producing obstructions. In this manner, as the process air 522 moves outward from the innermost airflow obstructions 1060 to the outer airflow obstructions 1062, one or more sets of intermediate airflow obstructions 1064 may be positioned between the innermost and the outer airflow obstructions 1060, 1062. The intermediate airflow obstructions 1064 can provide for a greater amount of turbulence than the innermost airflow obstructions 1060 where needed to prevent overheating of the airflow obstructions 548 as heat 514 is transferred from the process air 522 to the media surrounding the heat exchange structure 542.

Through this configuration, the heated process air 910 is quickly and efficiently cooled as the process air 522 moves through the heat exchange structure 542 without causing heat degradation of the airflow obstructions 548. Through these various configurations, the air leaving the heat exchange structure 542 and entering the condensing section 552 is in the form of the cooled process air 934, as described herein. Again, the cooled process air 934 typically has a temperature that is above the dewpoint of the process air 522 but is well below the temperature of the heated process air 910 entering the heat exchange structure 542.

According to the various aspects of the device, the various airflow obstructions 548 can take the form of any one of various shapes and profiles. The innermost airflow obstructions 1060 can take the form of two rings 730 that extend concentrically around the end of the inlet of the heat exchange structure 542. These rings 730 can extend downward from the inner surface 970 of the outer wall 572 and toward the inner wall 980 of the heat exchange structure 542. The positioning of the ends of the two rings 730 allows for an outward movement of at least a portion of the heated process air 910 in a generally outward direction 954. These rings 730, which can make up a range from approximately the first ring to approximately the six innermost rings 730 of airflow obstructions 548, produce a lesser amount of turbulence within the heated process air 910. Accordingly, this heated process air 910 is able to move more expediently from the innermost ring 730, to each subsequent ring 730 of the innermost airflow obstructions 1060 and into the intermediate airflow obstructions 1064, where included, and the outer airflow obstructions 1062.

Referring again to FIGS. 14-29, after leaving the innermost airflow obstructions 1060, the heated process air 910 can enter the outer airflow obstructions 1062, which may include the intermediate airflow obstructions 1064. The intermediate airflow obstructions 1064 can take the form of the circular frames, as described herein, or individual fins 138 that are attached to the inner surface 970 of the outer wall 572 for the heat exchange structure 542. Similarly, the remainder of the outer airflow obstructions 1062 can take the form of the individual circular frames 790, as described herein, or the individual fins 138 that are attached to the inner surface 970 of the outer wall 572 for the heat exchange structure 542.

In certain aspects of the device, the intermediate airflow obstructions 1064 and the outer airflow obstructions 1062 may be similarly configured. It is also contemplated that the intermediate airflow obstructions 1064 and the outer airflow obstructions 1062 can define different configurations of fins 138 or other airflow obstructions 548 to produce varying degrees of turbulence and residency of the heated process air 910 as it moves through the heat exchange portion 912 of the heat exchange structure 542.

Referring now to FIGS. 1-8 and 25-31, according to the various aspects of the device, the condensing tubes 140 of the condensing section 552 of the airflow path 524 can include a multicomponent condensing tube 140 that is used to extract heat 514 from the cooled process air 934. Each condensing tube 140 can include the outer sleeve 1050. Within the outer sleeve 1050, inserts 1052 can be disposed. These inserts 1052 can include the various condensing sets 576 of fins 138 through which the cooled process air 934 travels. As the cooled process air 934 travels through the condensing sets 576 of fins 138, heat 514 is extracted from the cooled process air 934 and delivered through the outer sleeve 1050 and into the water 530 surrounding the condensing section 552 of the reservoir 532. Each condensing tube 140 can include one insert 1052 within the outer sleeve 1050 or can include multiple inserts 1052 that are cooperatively disposed within the outer sleeve 1050. Typically, there are approximately two inserts 1052 within the outer sleeve 1050. The multiple inserts 1052 cooperate with one another to produce an outward biasing force 1080. This outward biasing force 1080 urges the outer surface of the inserts 1052 against the inward surface of the outer sleeve 1050. This biasing force 1080 minimizes the existence of gaps between the inserts 1052 and the outer sleeve 1050. By minimizing these gaps, the cooled process air 934 is directed through the condensing set 576 of fins 138 and little, if any, of the cooled process air 934 is able to escape around the outside of the inserts 1052. This configuration produces a more efficient transfer of heat 514 from the cooled process air 934 and into the media surrounding the condensing tubes 140.

According to the various aspects of the device, for assisting in the transfer of heat 514 from the heated process air 910 or cooled process air 934 and into the media, the temperature of the media surrounding the airflow path 524 can vary depending upon the temperature of the media within the reservoir 532. Through this configuration, the coolest water, which is typically the most dense, tends to travel downward and reside in an area surrounding the condensing section 552. Because this water is the coolest, heat 514 can typically be transferred from the cooled process air 934 and into the cold water surrounding the condensing tubes 140. While the term “cooled process air” is utilized herein, the temperature of the cooled process air 934 may be well above approximately 150° F. Contemporaneously, the cold water surrounding the condensing tubes 140 has typically received little heat 514 and may only be slightly above the temperature of tap water. Accordingly, the temperature differential between the cooled process air 934 and the cold water surrounding the condensing tubes 140 provides a sufficient differential to provide for the transfer of heat 514 from the cooled process air 934 into the cold water surrounding the condensing tubes 140. As the cold water within the reservoir 532 is heated, this now warmed water tends to rise within the reservoir 532, as described herein. Accordingly, gradients of temperature can be found within the reservoir 532 where the warmest water is positioned at the top of the reservoir 532 while the coldest water is positioned at the base of the reservoir 532 for the appliance 512. It is typical that the hot water outlet 162 for the appliance 512 is found proximate the top of the reservoir 532 so that the heated water 590 can be delivered from the heating appliance 512 for use within a particular structure.

According to the various aspects of the device, the deflecting member 950 of the heat exchange structure 542 is typically disposed within a receiver 1090 defined within the inner wall 980 of the heat exchange structure 542. Accordingly, the deflecting member 950 is fixed along the central axis 914 of the flue tube 132. As the heated process air 910 leaves the flue tube 132 and enters the heat exchange structure 542, the deflecting member 950 receives the heated process air 910, which has an extremely high temperature, which may be in excess of approximately 1,000 degrees Fahrenheit. The deflecting member 950, again, which is made of a heat-resistant material, defines a transition 1040 from the axial motion of the heated process air 910 within the flue tube 132 to the outward motion of the heated process air 910 within the heat exchange structure 542. In this manner, the deflecting member 950 redirects this heated process air 910 towards the plurality of airflow obstructions 548 within the heat exchange portion 912 of the heat exchange structure 542. Because the deflecting member 950 is made of a heat-resistant material, the heated process air 910 is able to move in a direction normal to the surface of the transition 1040. Accordingly, the deflecting member 950 tends to not experience heat degradation through interaction with the extreme amount of heat 514 that is received through the engagement with the heated process air 910.

The deflecting member 950 can be in the form of a block, a panel, a tile, or other similar member that is disposed within the inlet of the heat exchange structure 542 and received by the inner wall 980 thereof.

In certain aspects of the device, the deflecting member 950 can be contoured to promote the transitional redirection of heated process air 910 from along the central axis 914 to the generally outward direction 954 that may be generally perpendicular or oblique to the central axis 914. In such a configuration, the deflecting member 950 can take the form of various faceted surfaces, curved surfaces, angled surfaces, or other similar surfaces that are able to redirect the heated process air 910 from along the central axis 914 to a direction that is oblique or generally perpendicular to the central axis 914.

In an exemplary embodiment, water heater 100 may have a blower 170 positioned in the top region 102 of the water heater 100 and configured to generate downward flow of the combustion gases 612 into the single-pass heat exchanger 130. For example, the blower 170 is configured to produce pressure, e.g., negative or positive pressure depending on the positioning of blower 170, to facilitate flow of the combustion gases 612 through heat exchanger 130 and/or condensate collector 180. Suitable blowers and/or compressors will be understood by one of skill in the art.

Additionally, water heater 100 may include a condensate collector 180 or a condensation trap 180 positioned to receive condensate from the plurality of condensing tubes 140 of the downstream section 402 of the heat exchanger 130 and to deliver the condensate from the water heater 100. One of skill in the art would readily understand that any condensate collector 180 capable of separating combustion gases 612 and condensate 630 may be employed without deviating from the present invention. Condensate 630 and combustion gases 612 received from heat exchanger 130 enter condensate collector 180 from end portions 148 of the condensing tubes 140. Under gravity, condensate 630 flows to a lower elevation in condensate collector 180.

In another exemplary embodiment, a water heater 100 may include a water storage tank 110 configured to store water 530 to be heated. Water heater 100 has a combustion chamber 150, and a heat exchanger 130 configured to receive combustion gases 612 from the combustion chamber 150 and to transfer heat 514 to water 530 stored in the water storage tank 110.

The heat exchanger 130 includes the sensible heat exchange area 930 coupled to the flue tube 132. The flue tube 132 defines the upstream section 400 of the airflow path 524for the products of combustion received from the combustion chamber 150. In certain aspects of the device, the flue tube 132 can include the flue set 574 of heat exchange fins 138. Additionally, or optionally, the flue tube 132 comprises a cylindrical core, and the cylindrical outer wall surrounds the cylindrical core, such that the cylindrical outer wall and the cylindrical core define at least one flow path for the products of combustions received from the combustion chamber 150. The flue tube 132 comprises an internal surface extending along the axial direction 952, and wherein the flue set 574 of the heat exchange fins 138 extend from a portion of the internal surface and radially inward relative to the axial direction 952. In an exemplary embodiment, the cylindrical wall of the flue tube 132 includes the flue set 574 of heat exchange fins 138. This flue set 574 can be positioned along a portion of the interior of the flue tube 132, or can extend a majority of the height or the entirety of the height of the flue tube 132.

The sensible heat exchange area 930 includes an interior chamber 1030 having a plurality of heat conductive airflow obstructions 548, typically in the form of heat exchange fins 138. Additionally, or optionally, the interior chamber 1030 has an outer wall 572 with the plurality of heat exchange fins 138 extending therefrom. The outer wall 572 typically includes a concave surface (e.g., a domed or conical shape). The interior chamber 1030 can include a restrictor plate 310 positioned to divert the combustion gases 612 from the interior chamber 1030 to the condensing tubes 140. In an exemplary embodiment, the restrictor plate 310 includes a plurality of openings along an outer edge and according to a pattern, with the pattern defining a portion of the airflow path 524 for the products of combustion received from the combustion chamber 150.

The heat exchanger 130 further has a latent heat exchange area 932 coupled to the interior chamber 1030 of the heat exchange structure 542. The latent heat exchange area 932 includes the plurality of condensing tubes 140. Each of the plurality of condensing tubes 140 comprises a core, typically cylindrical in shape, extending in the axial direction 952, an internal surface, and a condensing set 576 of heat exchange fins 138 extending from a portion of the internal surface and radially inward relative to the axial direction 952. In an exemplary embodiment, the condensing set 576 of heat exchange fins 138 comprises aluminum.

In certain aspects of the device, the condensing tubes 140 can include a metallic outer sleeve 1050, typically made of steel or a steel alloy. Within the metallic outer sleeve 1050, each condensing tube 140 can include the condensing insert 1052 that defines the condensing set 576 of the heat exchange fins 138. The condensing insert 1052 can be a single generally cylindrical insert. The condensing insert 1052 can also be made up of two or more components that are inserted into the metallic outer sleeve 1050. These components link together and define an outward flexion of each of these components. This outward flexion presses the components against the inward surface of the metallic outer sleeve 1050. This pressure forms a tight seal around the insert 1052. By forming this seal, the combination of the outer sleeve 1050 and the insert 1052 directs the process air through the condensing set of heat exchange fins 138 of the condensing tubes 140. At the same time, the process air 522 is prevented from circumventing the condensing set 576 of fins 138 by preventing the combustion gases 612 from traveling between the outer sleeve 1050 and the insert 1052.

In still another embodiment, the invention provides a water heating system. The system includes components as discussed in the above embodiments, including a burner, such as burner 150, configured to create products of combustion and a vent configured to vent the products of combustion from the water heater 100. The system also has flue tube 132, defining an airflow path 524 for the products of combustion received from the burner 150 and extending toward the vent. The flue tube 132 includes a flue set 574 of the heat exchange fins 138. The system comprises a sensible heat exchange area 930 coupled to the flue tube 132, and the sensible heat exchange area 930 has an interior chamber 1030 having a plurality of fins 138. The system also includes latent heat exchange area 932 coupled to the interior chamber 1030. The latent heat exchange area 932 has the plurality of condensing tubes 140.

In operation of high efficiency gas-fired appliances (e.g., water heater) according to aspects of this invention, there are two heat exchanger sections: a heat exchanger section designed for high temperature flue gases (e.g., sensible heat exchange area 930) and a heat exchanger section designed for flue gases that drop below dewpoint so the higher heating value (HHV) of the fuel can be extracted through the phase change of vapor in the combustion gases 612 to liquid condensate 630 (e.g., latent heat exchange area 932).

The high temperature heat exchanger section can handle high temperature gases and is configured to extract most of the lower heating value (LHV) of the burned fuel. Further, the non-condensing heat exchanger section does not typically experience condensation that happens when flue gases reach the respective dewpoint.

The latter heat exchanger section preferably provides a sufficient surface area in the coldest area of the heating appliance to drop flue gases below dewpoint (e.g. approximately 150° F.). This condensing heat exchanger section is preferably designed to handle acid condensation that forms or can form from products of combustion. As an alternative to the embodiment disclosed in the figures, the sensible heat exchange area can be created using a long path-length of tubing that extends from the top of the tank to the bottom of the tank, which then returns to the top to enter the condensing region.

A single-pass heat exchanger 130 like the embodiment disclosed in the figures preferably overcomes one or more challenges, such as: (1) preferably avoiding the need for a recirculation pump to prevent overheating at the top of the tank; (2) preferably avoiding encountering limitations on how many BTUs can be handled by the design; and (3) preferably avoiding complexity to create enough surface area for the required BTUs of the appliance.

As noted above, water heater 100 includes a single-pass heat exchanger 130, in which combustion gases 612 are directed into a flue tube 132, which preferably includes baffling or fins to assist in more uniform heat extraction.

The medial section 404 includes an upper heat exchange surface 304, which extends radially outwardly relative to the upstream section 400 and the downstream section 402. As described herein, this shape of the medial section 404 reduces the area within the tank provided for vertical flow of water 530 in the water storage tank 110 between an elevation corresponding to the downstream section 402 and an elevation corresponding to the upstream section 400. In this manner, relatively cooler water 592 remains in a lower interior of the water storage tank 110 while warmer water resides in an upper interior of the water storage tank 110. Additionally, because the upper heat exchange surface 304 of the heat exchange structure 542 extends radially outwardly, heat 514 extraction is spread out over a horizontal plane within the heat exchange structure 542 of the medial section 404. Heat conductive airflow obstructions 548, such as the heat exchange fins 138, further increase surface area of contact between the metal of the heat exchanger and exhaust gases. Accordingly, as the combustion air or process air 522 engages the airflow obstructions 548, heat 514 from the process air 522 is transferred by the heat exchange fins 138. In turn, this heat is transported by conduction to the water-backed surface of the upper heat exchange surface 304. Thus, the heat exchange fins 138 within the interior chamber 1030 increase the thermal flux of the heat exchange structure 542 and increase the BTU capability of the water heater or the water heater system. One skilled in the art would understand that the present invention may not require the heat exchange fins within an appliance that requires lower BTUs.

Still further, the transition 1040 positioned adjacent or below the heat exchanger fins 138 to force flue gases through the fins 138, thereby improving heat exchange between the combustion gases 612 and the water-backed heat exchange structure 542. In operation, combustion gases 612 exit the interior chamber 1030 of the heat exchange structure 542, which houses the heat exchange fins 138, via the outer periphery of the upper heat exchange surface 304. In certain aspects of the device, the outer periphery of the heat exchange area is defined by a restrictor plate 310, as described herein.

One skilled in the art would understand from the description herein, that the configuration (e.g., geometry, arrangement, etc.) of the heat exchanger fins 138 within the interior chamber 1030 of the medial section 404 and relative to one or more components of medial section 404 (e.g., transition 1040, etc.) is not limited to what is illustrated in the figures. Rather, the heat exchanger fins 138 and transition 1040 are positioned relative to each other and within the interior chamber 1030 of the medial section 404 to divert the combustion gases 612 toward the heat exchange fins 138 and more evenly distribute the combustion gases 612 into the condensing tubes 140.

Regarding the condensing tubes 140, the individual condensing tubes 140 may have a relatively smaller diameter compared to that of the flue tube 132. For example, the condensing tubes 140 are designed to withstand acidic condensation. To achieve this, aluminum fins 138 or baffling which are thermally coupled to the condensing tubes 140 are provided and designed to extract heat 514 from the combustion gases 612 while protecting the condensing tubes 140 from acidic condensation. Additionally, or optionally, the condensing set 576 of the fins 138 are designed for maximum surface area to extract heat 514 from the flue gases and conduct this heat 514 to the water-backed walls of the condensing tubes 140. Alternatively, the condensing tubes 140 can be lined with glass and include baffling to extract heat from the flue gases into the water-backed walls of the tubes.

According to the various aspects of the device, the configuration of the airflow path 524 and the various airflow obstructions 548 defined therein creates a heat exchange appliance 512 that can extract a great amount of heat 514 from heated process air 910 such that the heated process air 910 moves through the airflow path 524 through a single pass only and does not need to be recirculated through the airflow path 524 to extract greater amounts of heat. A single pass of the heated process air 910 through the airflow path 524 extracts enough heat 514 to cause the condensation of humidity within the process air 522 within the condensing section 552 of the airflow path 524.

According to an aspect of the present invention, heating system for a water heating appliance includes a heater for generating heated process air, a blower for delivering the heated process air through an airflow path, a flue that defines an upstream section of the airflow path, a heat exchange structure disposed downstream of the flue and defining a medial section of the airflow path, and a condensing section that defines a downstream section of the airflow path and is disposed downstream of the heat exchange structure. The heat exchange structure includes a heat exchange portion having airflow obstructions that generate a turbulence and transfer heat from the heated process air to a media surrounding an outer surface of the heat exchange structure. The airflow path within the heat exchange portion extends outward and generally perpendicular to a direction of the airflow path within the flue.

According to another aspect, the airflow obstructions include a plurality of fins, wherein each fin of the plurality of fins is positioned in an angular orientation with respect to adjacent fins of the plurality of fins.

According to another aspect, the flue and the heat exchange structure define a sensible heat exchange area, and wherein the condensing section defines a latent heat exchange area that causes a condensation of humidity within the heated process air, wherein the heated process air transitions to cooled process air as the heated process air moves through the airflow path.

According to another aspect, the heated process air moves through the flue along a central axis of the airflow path, wherein the condensing section includes a plurality of condensing tubes that are oriented parallel with the central axis, and wherein the heat exchange portion of the heat exchange structure directs the heated process air in a direction that is oblique to the central axis.

According to another aspect, the heat exchange structure includes an outer wall that forms one of a conical shape and a dome shape, and wherein the plurality of fins are attached to an inner surface of the outer wall.

According to another aspect, the heat exchange structure includes an inner wall that opposes the outer wall to define a portion of the airflow path therebetween, and wherein the plurality of fins are disposed between the outer wall and the inner wall.

According to another aspect, the plurality of fins are positioned in concentric rings of fins, and wherein each ring of fins is disposed at an angle with respect to a corresponding concentric ring.

According to another aspect, the condensing section includes an outlet, and wherein the flue, the heat exchange structure, and the condensing section cooperate to define a single pass condensing heat exchanger where the heated process air moves sequentially through the airflow path.

According to another aspect, the transition of the heat exchange structure directs the heated process air toward the airflow obstructions, and wherein the transition of the heat exchange structure includes a heat-resistive material.

According to another aspect, the flue defines a central axis, and wherein the heated process air moves through the flue along the central axis, and wherein the transition redirects the heated process air to travel in a direction that is one of perpendicular to the central axis and oblique to the central axis.

According to another aspect, the condensing section includes a plurality of condensing tubes that are oriented parallel with the central axis, and wherein the plurality of condensing tubes direct the heated process air from the heat exchange structure to an outlet.

According to another aspect, the airflow obstructions include a plurality of heat exchange fins, wherein each fin of the plurality of fins is positioned in an angular orientation with respect to adjacent fins of the plurality of fins.

According to another aspect, the plurality of fins are positioned in concentric rings of fins.

According to another aspect, the heat exchange structure includes an outer wall that forms one of a conical shape and a dome shape, and wherein the plurality of airflow obstructions are attached to an inner surface of the outer wall.

According to another aspect, the airflow obstructions include a plurality of fins, wherein each fin of the plurality of fins is positioned in concentric circles and positioned in an angular orientation with respect to adjacent fins of the plurality of fins.

It will be understood by one having ordinary skill in the art that construction of the described disclosure and other components is not limited to any specific material. Other exemplary embodiments of the disclosure disclosed herein may be formed from a wide variety of materials, unless described otherwise herein.

Number	Date	Country
63670331	Jul 2024	US
63655762	Jun 2024	US
63618024	Jan 2024	US

SINGLE PASS HIGH-EFFICIENCY CONDENSING WATER HEATER

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