SINGLE PIECE COMBUSTION PRODUCT DIVERTER FOR WATER HEATERS

Abstract

A fuel-fired water heater includes a top water outlet, a water tank, a top cover assembly having a top surface, wherein the top water outlet is disposed on the top surface to output water from the water tank, a multi-pass heat exchanger positioned in the water tank, wherein the multi-pass heat exchanger comprises flue tubes, and a top plenum at a top end portion of the water heater, wherein the top plenum has a first end and a second end.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and benefit of U.S. provisional patent application No. 63/428,198 filed Nov. 28, 2022, which is herein incorporated by reference.

FIELD

This application relates generally to water heaters, and more particularly to water heaters having single piece combustion product diverters.

BACKGROUND

Typical fuel-fired water heaters use fuels, such as natural gas, propane or oil, to heat water contained in a water tank of such water heaters. With such water heaters, a heat exchanger associated with the tank is typically used to heat the water. In some water heaters, hot gas passes through a heat exchanger once to heat the water. In other water heaters, the heat exchanger may include multiple branches, and the hot gas passes through the heat exchanger multiple times to heat the water. The multiple-branched heat exchanger can result in improved thermal efficiency. However, the arrangement of the multiple branches of the heat exchanger in the tank can present challenges to providing a top water outlet without degrading thermal efficiency of the water heater. In some cases, water heaters with a top water outlet may be preferable. Thus, a solution that allows for the construction of a water heater with a top water outlet and using a multiple-pass heat exchanger may be desirable.

A water heater is described in U.S. Pat. No. 10,801,748, the entire disclosure of which is incorporated herein by reference. This will be described in greater detail with reference to FIGS. 1-4.

FIG. 1 illustrates a perspective view of a water heater 100 that includes a water tank 102, a top cover assembly 104, and a bottom assembly 106. The water heater 100 also includes a combustion system 108 at the top end of the water heater 100. The combustion system 108 may include a down-fired burner, where hot gas flows downward into a multi-pass heat exchanger disposed in the water tank 102. The water heater 100 also includes a water inlet 112 that may be disposed, for example, closer to the bottom end of the water tank 102. The water tank 102 also includes a top water outlet 110 through the top cover assembly 104.

During operation of the water heater 100, unheated water enters the water tank 102 through the water inlet 112, and gas is heated by the combustion system 108. The unheated water gets heated inside the water tank by hot gas flowing through the multi-pass heat exchanger. The resulting heated water exits the water tank 102 through the top water outlet 110 in the top cover assembly 104. The hot gas that flows through the multi-pass heat exchanger may exit the water tank through a hot gas outlet in the bottom assembly 106.

The water heater 100 provides a top water outlet location along with the high efficiency of a multi-pass heat exchanger. By providing the top water outlet 110, the water heater 100 provides a fuel-fired water heater with a top water outlet location that is preferable in some installations.

FIG. 2 illustrates a top view of the inside of the water tank 102 of the water heater 100 of FIG. 1. FIG. 3 illustrates a cross-sectional view of the water heater of FIG. 1 without the water tank. Referring to FIGS. 1-3, the water heater 100 includes the water tank 102. A multi-pass heat exchanger 230 is positioned in the water tank 102. The multi-pass heat exchanger 230 includes a first-pass flue tube 202, second-pass flue tubes 204, 206, 208, 210, and third-pass flue tubes 212, 214, 216, 218, 220, 222, 224, 226.

The second-pass flue tubes 204, 206, 208, and 210 extend out radially from the first-pass flue tube 202 and curve/turn generally upward toward the top opening of the water tank 102. The second-pass flue tubes 204-206 are attached to the first-pass flue tube 202 forming a hot gas flow path from the first-pass flue tube 202 to the second-pass flue tubes 204-206. The hot gas in the first-pass flue tube 202 is provided by the combustion system 108, which can be a down-fired system, as more clearly illustrated in FIG. 1.

The second-pass flue tubes 204-210 are substantially parallel to the first-pass flue tube 202 after curving/turning upward. The second-pass flue tubes 204-210 may branch out from the first-pass flue tube 202 proximal to a bottom end of the water tank 102 and may extend upward for a substantial portion of the height of the water tank 102. In some embodiments, the second-pass flue tubes 204-210 may have curves or other variations in extending upward toward the top opening of the water tank 102. Top ends of the second-pass flue tubes 204-210 are terminated in top flues in the top cover assembly 104 of the water heater 100 or may otherwise be in fluid communication with the top flues in the top cover assembly 104 of the water heater 100. For example, the second-pass flue tubes 204, 206 are terminated in a first kidney-shaped top plenum 302, and the second-pass flue tubes 208, 210 are terminated in a second kidney-shaped top plenum 304.

FIG. 4 illustrates a partial detailed view of the top cover assembly 104 of the water heater 100 of FIG. 1 according to an embodiment. Referring to FIGS. 1-4, the top cover assembly 104 includes a tank cover plate 402, a top cover 404, and flue covers 406, 408. The top cover assembly 104 also includes gaskets 412, 414. The gasket 412 are positioned between the diverter 406 and the tank cover plate 402, and the gasket 414 are positioned between the diverter 408 and the tank cover plate 402.

The diverter 406 and the tank cover plate 402 may define the first kidney-shaped top plenum 302, and the diverter 408 and the tank cover plate 402 may define the second kidney-shaped top plenum 304. The gaskets 412, 414 may provide a more reliable seal of the kidney-shaped top plenums 302, 304. The tank cover plate 402 may include holes matching the arrangement of the flue tubes of the heat exchanger 230. The combustion system 108 may include a pipe 410 that is inserted into the first-pass flue tube 202 of the heat exchanger 230. The blower of the combustion system 108 may flow air into the first-pass flue tube 202 through the pipe 410.

The third-pass flue tubes 212-226 may extend in the cavity of the water tank 102 from the top end of the water tank 102 to a bottom end of the water tank 102. Top end openings of the third-pass flue tubes 212-226 are terminated or may otherwise be in fluid communication with the kidney-shaped top plenums 302, 304 in the top cover assembly 104. Hot gas from the second-pass flue tubes 204-210 flows to the third-pass flue tubes 212-226 through the top plenums 302, 304 in the top cover assembly 104. For example, the top end openings of the third-pass flue tubes 212-218 are terminated in the first kidney-shaped top plenum 302 to receive hot gas from the second-pass flue tubes 204, 206, and the top end openings of the third-pass flue tubes 220-226 are terminated in the second kidney-shaped top plenum 304 to receive hot gas from the second-pass flue tubes 208, 210.

The bottom end openings of the third-pass flue tubes 212-226 are terminated in the bottom assembly 106 through openings in a top cover 228 of the bottom assembly 106. For example, the bottom assembly 106 may include a bottom flue 306, and hot gas flowing through the third-pass flue tubes 212-226 may flow to the bottom flue 306 and exit the bottom assembly 106 through a hot gas outlet 310 of the bottom assembly 106.

In operation, as shown in FIG. 2, water is filled in the water heater 102. Hot air is passed downward toward the bottom of the water heater 100 through the first-pass flue tube 202, which heats the water surrounding the first-pass flue tube 202 via conduction. By heating the water surrounding the first-pass flue tube 202, the hot air in the first-pass flue 202 is cooled somewhat as it passes through.

The somewhat-cooled hot air from the first-pass flue tube 202 is then passed upward through the second-pass flue tubes 204, 206, 208, and 210, each of which additionally heats the water surrounding the respective second-pass flue tubes 204, 206, 208, and 210. Again, by heating the water surrounding the second-pass flue tubes 204, 206, 208, and 210, the somewhat-cooled hot air is then further cooled.

The further cooled hot air from the second-pass flue tubes 204 and 206 is diverted by the first kidney-shaped top plenum 302 and into the third-pass flue tubes 212, 214, 216, and 230. The further cooled hot air from the second-pass flue tubes 208 and 210 is diverted by the second kidney-shaped top plenum 304 and into the third-pass flue tubes 220, 222, 224, and 226.

The further-cooled hot air from the second-pass flue tubes 204, 206, 208, and 210, is then passed downward toward the bottom of the water heater 100 through the third-pass flue tubes 212-226, each of which additionally heats the water surrounding the respective the third-pass flue tubes 212-226. Again, by heating the water surrounding the third-pass flue tubes 212-226, the further-cooled hot air is then still further cooled.

Accordingly, a portion of water in the water heater 100 that is surrounding the flue tubes is heated by conduction via the multiple passes of the hot air through the multiple flue tubes. The remainder of the water in the water heater 100 is heated via a combination of conduction with the heated water and convection. However, as shown in FIG. 2, the areas 232 and 234 illustrate where there are no flue tubes. As such, these areas of the water heater 100 can only be heated via conduction from other heated water and convection. This reduces the thermal efficiency of the hot water heater.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is set forth with reference to the accompanying drawings. In some instances, the use of the same reference numerals may indicate similar or identical items. Various embodiments may utilize elements and/or components other than those illustrated in the drawings, and some elements and/or components may not be present in various embodiments. Throughout this disclosure, depending on the context, singular and plural terminology may be used interchangeably.

FIG. 1 illustrates a water heater.

FIG. 2 illustrates a detailed view of a portion of the water heater of FIG. 1.

FIG. 3 illustrates a cross-sectional view of the water heater of FIG. 1 without the water tank.

FIG. 4 illustrates a partial detailed view of a top cover assembly of the water heater of FIG. 1.

FIG. 5 illustrates a perspective view of a water heater in accordance with one or more embodiments of the present disclosure.

FIG. 6A illustrates a top view of the inside of the water tank of the water heater of FIG. 5 in accordance with one or more embodiments of the present disclosure.

FIG. 6B illustrates a perspective view of a heat exchanger in accordance with one or more embodiments of the present disclosure.

FIG. 6C illustrates a side view of the heat exchanger of FIG. 6B in accordance with one or more embodiments of the present disclosure.

FIG. 6D illustrates a top view of the heat exchanger of FIG. 6B in accordance with one or more embodiments of the present disclosure.

FIGS. 6E-6S illustrate example baffles of the heat exchanger of FIGS. 6B-6D in accordance with one or more embodiments of the present disclosure.

FIG. 7 illustrates a cross-sectional view of the water heater of FIG. 5 in accordance with one or more embodiments of the present disclosure.

FIG. 8 illustrates a top view of a tank cover plate of the water heater of FIG. 5 in accordance with one or more embodiments of the present disclosure.

FIG. 9A illustrates a top view of a top flue cover of the water heater of FIG. 5 in accordance with one or more embodiments of the present disclosure.

FIG. 9B illustrates a bottom view of the top flue cover of the water heater of FIG. 5 in accordance with one or more embodiments of the present disclosure.

FIG. 10A illustrates a top view of a working example of the top flue cover of the water heater of FIG. 5 in accordance with one or more embodiments of the present disclosure.

FIG. 10B illustrates a bottom view of the working example of the top flue cover of the water heater of FIG. 5 in accordance with one or more embodiments of the present disclosure.

FIG. 11A illustrates a cross-sectional view of the top flue cover of FIG. 10A as cut along a line A-A in accordance with one or more embodiments of the present disclosure.

FIG. 11B illustrates a detailed view of a portion of FIG. 11A, showing the non-limiting measurements of a gasket track in accordance with one or more embodiments of the present disclosure.

FIG. 11C illustrates a detailed view of the top flue cover of FIG. 10B as cut along a line B-B, showing the non-limiting measurements of a bump-out in accordance with one or more embodiments of the present disclosure.

FIG. 12 illustrates a method of heating water in accordance with one or more embodiments of the present disclosure.

DETAILED DESCRIPTION

The systems and methods disclosed herein provides improved thermal efficiency. For example, in certain embodiments, a water heater includes a single horse-shoe-shaped plenum in conjunction with a multi-pass heat exchanger that has additional third-pass flue tubes, which increases thermal efficiency in a water tank. In some instances, the water tank may be a 120 gallon water tank. In other instances, the water tank may be less than or greater than 120 gallons. The water tank may be generally cylindrical or the like. The water tank may be any suitable size, shape, or configuration.

Turning now to the drawings, an example water heating system and method of heating water in accordance with aspects of the present disclosure will now be described in greater detail with reference to FIGS. 5-12.

FIG. 5 illustrates a perspective view of a water heater 500 in accordance with one or more embodiments of the present disclosure. In some embodiments, the water heater 500 includes water tank 502, a top cover assembly 504, and a bottom assembly 506. The water heater 500 also includes a combustion system 508 at the top end of the water heater 500. For example, the combustion system 508 may include a down-fired burner, where hot gas flows downward into a multi-pass heat exchanger disposed in the water tank 502. The water heater 500 also includes a water inlet 512 that may be disposed, for example, closer to the bottom end of the water tank 502. The water tank 502 also includes a top water outlet 510 through the top cover assembly 504.

In some embodiments, the top cover assembly 504 includes top flues that interface with second-pass and third-pass flue tubes of the multi-pass heat exchanger. The multi-pass heat exchanger has a configuration that allows the location of the water outlet 510 in the top cover assembly 504 at the top end of the water heater 500. The bottom assembly 506 may also include a bottom flue that interfaces with the third-pass flue tubes of the multi-pass heat exchanger, where the hot gas exits the water heater 500 through a hot gas outlet in the bottom assembly 506.

During operation of the water heater 500, unheated water enters the water tank 502 through the water inlet 512, and gas is heated by the combustion system 508. The unheated water gets heated inside the water tank by hot gas flowing through the multi-pass heat exchanger. The resulting heated water exits the water tank 502 through the top water outlet 510 in the top cover assembly 504. The hot gas that flows through the multi-pass heat exchanger may exit the water tank through a hot gas outlet in the bottom assembly 506.

The water heater 500 provides a top water outlet location along with the high efficiency of a multi-pass heat exchanger. By providing the top water outlet 510, the water heater 500 provides a fuel-fired water heater with a top water outlet location that is preferable in some installations.

In some embodiments, the water heater 500 and/or one or more components of the water heater 500 may have a different shape than shown without departing from the scope of this disclosure. In some alternative embodiments, the water inlet 512 may be at a different location than shown without departing from the scope of this disclosure. In some alternative embodiments, the top water outlet 510 may be at a different location on the top cover assembly than shown without departing from the scope of this disclosure.

FIG. 6A illustrates a top view of the inside of the water tank 502 of the water heater 500 of FIG. 5 in accordance with one or more embodiments of the present disclosure. FIG. 7 illustrates a cross-sectional view of the water heater of FIG. 5. Referring to FIGS. 5-7, in some embodiments, the water heater 500 includes the water tank 502. A multi-pass heat exchanger 602 is positioned in the water tank 502. The multi-pass heat exchanger 602 includes a first-pass flue tube 604, second-pass flue tubes 606, 608, 610, and 612, and third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640. The hot gas in the first-pass flue tube 604 is provided by the combustion system 508, which can be a down-fired system, as more clearly illustrated in FIG. 7.

FIG. 6B illustrates a perspective view of multi-pass heat exchanger 602. FIG. 6C illustrates a side view of the multi-pass heat exchanger 602. 6D illustrates a top view of the multi-pass heat exchanger 602. The multi-pass heat exchanger 602 provides for greater transference of heat over existing heat exchangers at higher inputs based on a larger surface area and increased air flow to allow the higher rate inputs. The multi-pass heat exchanger 602 shown in FIGS. 6A-6D may be configured to allow for effective heat transfer in a larger capacity water heater, such as a 120 gallon capacity water heater, for example. However, the multi-pass heat exchanger 602 may also be used in water heaters of other capacities as well. The multi-pass heat exchanger 602 may be made from a carbon steel material that is then coated porcelain coated but may also be made from stainless steel and/or any other type of material.

In embodiments, the multi-pass heat exchanger 602 utilizes a down fire combustion system (not shown in the figure), such as combustion system 508 (or any other combustion system described herein), mounted to a top portion 643 the multi-pass heat exchanger 602. The combustion system is coupled to the first-pass flue tube 604 such that the heat produced by the combustion system is expelled downwards into the first-pass flue tube 604. The first-pass flue tube 604 may include a 6″ diameter wedge portion connected to an 8″ diameter inch expansion portion, which may extend down the length of the first-pass flue tube 604. These dimensions are merely exemplary and the first-pass flue tube 604 may also be configured in any other size as well.

The first-pass flue tube 604 may also be supported by a support pipe 640, which may be welded to the heat exchanger 602. The support pipe 641 may not necessarily include an aperture, but rather may merely serve as a mechanism to support the first-pass flue tube 604 of the multi-pass heat exchanger 602. In some instances, the support pipe 641 may not be included and the first-pass flue tube 604 may be supported within the multi-pass heat exchanger 602 in any other suitable manner.

The heat produced by the combustion system travels down the first-pass flue tube 604 to the second-pass flue tubes 606, 608, 610, and 612. The heat then travels up the second-pass flue tubes 606, 608, 610, and 612, and into the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640 via the diverter (for example, diverter 406, diverter 408, diverter 710, and/or any other diverter described herein) at the top portion 643 of the multi-pass heat exchanger 602. Finally, the heat travels down the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640 and into a collector (not shown in the figure) located at a bottom portion 642 of the multi-pass heat exchanger 602. The collector allows the combustion gases to be vented out from the multi-pass heat exchanger 602 and also collects any condensate produced by the flue tubes as a byproduct of the combustion process. The collector may be a polymer material, however, other types of materials are also possible.

The multi-pass heat exchanger 602 may be more efficient than existing heat exchangers by allowing the heat of combustion gases within the heat exchanger 602 to be reduced from approximately 2100° F. to approximately 120° F. when the combustion gases are exhausted from the multi-pass heat exchanger 602 (based on the transference of the heat from the multi-pass heat exchanger 602). For example, the heat may be approximately 1800-2100° F. in the first flue tube 604, may be approximately 1200-1400° F. upon entering the second-pass flue tubes 606, 608, 610, and 612, may be below 500° F. upon entering the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640, and may be approximately 120° F. or below upon exiting the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640, resulting in an approximately 95% efficiency of the multi-pass heat exchanger 602. The final temperature at the end of the process may also depend on the altitude in which the multi-pass heat exchanger 602 is provided and the set point of the water heater.

In embodiments, the second-pass flue tubes 606, 608, 610, and 612 may be 3″ in diameter, and the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640 may be 2″ in diameter. However, the size, shape, number, arrangement, etc. of the first-pass flue tube 604, second-pass flue tubes 606, 608, 610, and 612, and third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640 is merely exemplary. For example, in other embodiments, the number of second-pass flue tubes may be increased from four to six and the number of third-pass flue tubes may be decreased.

Additionally, the second-pass flue tubes 606, 608, 610, and 612 may also include one or more baffles to slow the progression of the combustion heat through the second-pass flue tubes 606, 608, 610, and 612, which provides for maximum transference of heat form the heat exchanger 602 to the water in the water heater. Baffles may also be provided within the first-pass flue tube 604, the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640, and/or in any other combination of the different flue tubes.

FIGS. 6E-6S illustrate example baffles of the heat exchanger of FIGS. 6B-6D. FIGS. 6E-6S show various examples of baffles 652 that may be provided in various flue tubes 650 (which may be any of the flue tubes, such as first-pas flue tubes, second-pass flue tubes, third-pass flue tubes, etc.) or combinations of flue tubes (for example, baffles may be provided in both the second-pass flue tubes, third-pass flue tubes, etc.). Additionally, FIG. 6E shows baffles 652 inserted into top of flue tube 650 and extending into the flue tube 650 to a predetermined depth (which may be any depth, including the entire length of the flue tube). FIGS. 6Q-6S show details of the designed gap between the wall of the flue tube 650 and baffle 652. In embodiments, the baffles may be bent in direction against a main center spine of a flue tube to slow down the progression of the heat through the flue tube, in turn increasing the transference of heat from the multi-pass heat exchanger 602 to the water in the water heater. The baffles may be made from a stainless steel material, however, other materials are also possible.

FIG. 7 illustrates a cross-sectional view of the water heater 500 in accordance with one or more embodiments of the present disclosure. As shown in FIG. 7, the water heater includes a horse-shoe-shaped top plenum 702 located at the top of the water heater 500, a bottom flue located at the bottom of the water heater 500, a flue cover 708, a horse-shoe-shaped diverter 710, a tank cover plate 712, a gasket 714, a pipe 716, a hot gas outlet 718, and a plurality of screws, a sample of which is indicated as screw 706. In embodiments, the horse-shoe-shaped diverter 710 may be a single piece diverter and the diverters 406 and 408 may be two-piece diverters.

In some embodiments, the second-pass flue tubes 606, 608, 610, and 612 extend out radially from the first-pass flue tube 604 and curve/turn generally upward toward the top opening of the water tank 502. This is more clearly shown in FIG. 7, wherein the second-pass flue tube 606, for example extends out radially from the first pass flue tube 604 and curves/turns generally upward toward the tope opening of the water tank 502. The second-pass flue tubes 606, 608, 610, and 612 are attached to the first-pass flue tube 604 forming a hot gas flow path from the first-pass flue tube 604 to the second-pass flue tubes 606, 608, 610, and 612. This is more clearly shown in FIG. 7, wherein the second-pass flue tube 606, for example is attached to the first pass flue tube 604 forming a hot gas flow path from the first-pass flue tube 604 to the second-pass flue tube 606.

As used herein, the phrase “horse-shoe-shaped plenum” refers to the three-dimensional volume of the plenum having a semi ring torus, partial annulus, or similar shape. That is, the plenum has a curved or semi-circular profile in which opposed ends are positioned at least at 180 degrees from one another, relative to the circle defining the semi-circular profile, and in which the opposed ends are separated from one another so as not to make contact with one another.

Returning to FIG. 6, in some embodiments, the second-pass flue tubes 606, 608, 610, and 612 may be substantially parallel to the first-pass flue tube 604 after curving/turning upward. The second-pass flue tubes 606, 608, 610, and 612 may branch out from the first-pass flue tube 604 proximal to a bottom end of the water tank 502 and may extend upward for a substantial portion of the height of the water tank 502. In some embodiments, the second-pass flue tubes 606, 608, 610, and 612 may have curves or other variations in extending upward toward the top opening of the water tank 502. Top ends of the second-pass flue tubes 606, 608, 610, and 612 may be terminated in top flues in the top cover assembly 504 of the water heater 500 or may otherwise be in fluid communication with the top flues in the top cover assembly 504 of the water heater 500. For example, the second-pass flue tubes 606, 608, 610, and 612 may be terminated in the horse-shoe-shaped top plenum 702.

In some embodiments, the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640 may extend in the cavity of the water tank 502 from the top end of the water tank 502 to a bottom end of the water tank 502. Top end openings of the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640 may be terminated or may otherwise be in fluid communication with the horse-shoe-shaped top plenum 702 in the top cover assembly 504. Hot gas from the second-pass flue tubes 606, 608, 610, and 612 flows to the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640 through the horse-shoe-shaped top plenum 702 in the top cover assembly 504.

In some embodiments, the bottom end openings of the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640 may be terminated in the bottom assembly 506 through openings in a top cover 642 of the bottom assembly 506. For example, the bottom assembly 506 may include a bottom flue 704, and hot gas flowing through the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640 may flow to the bottom flue 704 and exit the bottom assembly 506 through a hot gas outlet 310 of the bottom assembly 506.

In some embodiments, the first-pass flue tube 604, the second-pass flue tubes 606, 608, 610, and 612, and the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640 may be configured with respect to each other to allow for placing the hot water outlet 510 in the top cover assembly 504 of the water heater 500. For example, the second-pass flue tubes 606, 608, 610, and 612 may be intermingled with the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640 around the first-pass flue tube 604. The second-pass flue tubes 606 and 608 are less than ninety degrees apart from each other relative to the circle defining a cross-section of the hot water heater 500, and the second-pass flue tubes 610 and 612 are less than ninety degrees apart from each other relative to the circle defining the cross-section of the hot water heater 500. Further, the second-pass flue tubes 606 and 608 are each greater than 90 degrees apart from the second-pass flue tubes 610 and 612 relative to the circle defining the cross-section of the hot water heater 500. Each second-pass flue tube 606, 608, 610, and 612 is also flanked by one of the third-pass flue tubes 614, 616, 618, 620, 630, 632, 634, and 636, where two of the third-pass flue tubes 614, 616, 618, 620, 630, 632, 634, and 636 are interspersed between two of the second-pass flue tubes 606, 608, 610, and 612. Further, the third-pass flue tubes 622, 624, 626, and 628 are disposed in area 640 between the third-pass flow tubes 620 and 630.

In general, the third-pass flue tubes 614, 616, 618, 620, 630, 632, 634, and 636 are each spaced from an adjacent one of the second-pass flue tubes 606, 608, 610, and 612 by the same circumferential distance relative to the circle defining the cross-section of the hot water heater 500. As such, compared to third-pass flue tubes that are between second-pass flue tubes and that are separated by less than ninety degrees relative to the circle defining the cross-section of the hot water heater 500, a much larger circumferential space relative to the circle defining the cross-section of the hot water heater 500 exists between third-pass flue tubes 614 and 636 that are between second-pass flue tubes 606 and 612. The much larger circumferential space relative to the circle defining the cross-section of the hot water heater 500 between the third-pass flue tubes 614 and 636 aligns with the top water outlet 510, as shown in FIG. 5. This allows the water heater 500 to have the top water outlet 510 without degrading the thermal efficiency of the water heater 502.

In contrast with typical water heaters discussed above with reference to FIGS. 1-4, and as will be described in greater detail below, in accordance with aspects of the present disclosure, hot air passed through the third-pass flue tubes 622, 624, 626, and 628 will heat water in the tank that is surrounding the third-pass flue tubes 622, 624, 626, and 628 via conduction. Similarly, as will be described in greater detail below, hot air passed through the third-pass flue tubes 638 and 640 will heat water in the tank that is surrounding the third-pass flue tubes 638 and 640 via conduction. Therefore, the volume of the columns of water in within the water tank as shown by areas 644 and 646 will not rely solely on conduction with other heated water in water tank 500 and convection for heating. On the contrary, in accordance with aspects of the present disclosure, the volume of the columns of water in within the water tank as shown by areas 644 and 646 will additionally be heated by conduction from third-pass flue pipes. This will greatly increase the thermal efficiency of the water heater 500 over the water heater 100.

In some alternative embodiments, the second-pass flue tubes 606, 608, 610, and 612 and the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640 may be interspersed with each other in a different arrangement without departing from the scope of this disclosure. In some alternative embodiments, the flue tubes of the heat exchanger 602 may have different absolute and relative dimensions without departing from the scope of this disclosure. In some alternative embodiments, the heat exchanger 602 may include fewer or more flue tubes than shown without departing from the scope of this disclosure. In some instances, the second-pass flue tubes may include a 3″ outer diameter, and the third-pass flue tubes may include a 2″ outer diameter. Multiple combination of tube sizes can be accommodated and may be used herein. For example, larger tanks and diverters may allow for larger tubes. The tubes may be any suitable size, shape, or configuration.

Referring to FIGS. 5-7, in some embodiments, the top cover assembly 504 includes the tank cover plate 712, the top cover 708, and the flue cover 708. In some embodiments, the top cover assembly 504 also includes gasket 714, 414. For example, the gasket 714 may be positioned between the flue cover 708 and the tank cover plate 712, and the gasket 414 may be positioned between the diverter 408 and the tank cover plate 712.

In some embodiments, the flue cover 708 and the tank cover plate 712 may define the horse-shoe-shaped top plenum 702. The gasket 714 may provide a more reliable seal of the horse-shoe-shaped top plenum 702. This will be described in greater detail with reference to FIGS. 8 and 9.

FIG. 8 illustrates a top view of the tank cover plate 712 of the water heater 500 in accordance with one or more embodiments of the present disclosure.

Referring to FIGS. 5-8, in some embodiments, the tank cover plate 712 may be positioned at the top end of the water tank 502. The tank cover plate 712 may have holes arranged in a configuration that matches the configuration of the flue tubes of the heat exchanger 602.

To illustrate, the tank cover plate 712 may have tube holes 804, 806, 808, and 810 that are sized to receive the second-pass flue tubes 612, 610, 608, and 606, respectively. The tank cover plate 712 may have tube holes 812, 814, 816, 818, 820, 822, 824, 826, 828, 830, 832, 834, 836, and 838, that are sized to receive the third-pass flue tubes 638, 636, 634, 632, 630, 628, 626, 624, 622, 620, 618, 616, 614, and 640, respectively. The tank cover plate 712 also includes a water outlet hole 802 that may be aligned with the top water outlet 510 of the water heater 500. For example, a water outlet pipe may be extended down into the water tank 502 through the water outlet hole 802. By arranging the tube holes 804, 806, 808, and 810 and the tube holes 812, 814, 816, 818, 820, 822, 824, 826, 828, 830, 832, 834, 836, and 838 to correspond to the second-pass flue tubes 612, 610, 608, and 606 and the third-pass flue tubes 638, 636, 634, 632, 630, 628, 626, 624, 622, 620, 618, 616, 614, and 640, respectively, an adequate area is provided between the tube holes 812 and 838 of the tank cover plate 712 to place the water outlet hole 802 such that the water heater 500 can include the top water outlet 510 in the top cover assembly 504. In some instances, the water outlet hole 802 may include a 1.5″ connection. Smaller connections can be accommodated. Larger size tanks can accommodate larger connections. The water outlet hole 802 may be any suitable size, shape, or configuration.

In some embodiments, a central opening 840 may be positioned to align with the first-pass flue tube 604 and to receive a mounting flange 844 above the first-pass flue tube 604, as shown in FIG. 8C.

In some embodiments, mounting standoffs, such as a mounting standoff 842 may be used to securely attach the flue cover 708 to the tank cover plate 712 using, for example, screws. By using the mounting standoffs, screws that are used to attach the flue cover 708 to the tank cover plate 712 can avoid penetrating through the tank cover plate 712.

FIG. 9A illustrates a top view of the horse-shoe-shaped diverter 710. FIG. 9B illustrates a bottom view of the horse-shoe-shaped diverter 710. As shown in the figures, the horse-shoe-shaped diverter 710 has a semicircular portion 902 bounded by one end 904 and a second end 906, wherein the end 904 is separated from the end 906 by a space 908. The horse-shoe-shaped diverter 710 additionally has a single mounting lip 910 that spans an outer periphery 912 of the semicircular portion 902, an outer periphery 914 of the end 904, an inner periphery 916 of the semicircular portion 902, and an outer periphery 918 of the end 906.

The mounting lip 910 includes a plurality of screw holes. In this instance, the mounting lip 910 includes screw holes 920, 911, 924, 926, 928, 930, 932, and 934 about the outer periphery 912 of the semicircular portion 902, and includes screw holes 936, 938, 940, 942, 944, and 946 about the inner periphery 916 of the semicircular portion 902. These screw holes enable the flue cover 708 to be fastened to the tank cover plate 712 using fasteners. The mounting lip 910 additionally includes divots 948 and 950, which may provide clearance for various other components.

As shown in FIG. 9B, a single gasket track 952 additionally runs about the outer periphery, around both ends of the horse-shoe shape and around the inner periphery. The gasket track 952 is bounded on an outer side by the mounting lip 910 and on an inner side by the horse-shoe-shaped plenum 702. The gasket track 952 is formed between a first protrusions 954 and a second protrusion 956.

The first protrusion 954 is continuous and circumscribes the outer periphery 912 of the semicircular portion 902, the outer periphery 914 of the end 904, the inner periphery 916 of the semicircular portion 902, and the outer periphery 918 of the end 906. Similarly, the second protrusion is continuous and circumscribes the outer periphery 912 of the semicircular portion 902, the outer periphery 914 of the end 904, the inner periphery 916 of the semicircular portion 902, and the outer periphery 918 of the end 906. Thus, the gasket track 952 formed by the first protrusion 954 and the second protrusion 956 is continuous and circumscribes the outer periphery 912 of the semicircular portion 902, the outer periphery 914 of the end 904, the inner periphery 916 of the semicircular portion 902, and the outer periphery 918 of the end 906.

Further, the gasket track 952 has a plurality of bump-outs. In this instance, the gasket track 952 includes a bump-outs 958, 960, 962, and 964, each of which locally enlarge the horse-shoe-shaped plenum 702 to receive the slightly larger in diameter second-pass flue tubes 612, 610, 608, and 606, respectively.

In some embodiments, the horse-shoe-shaped diverter 710 may be positioned on the tank cover plate 712 covering the second-pass flue tubes 612, 610, 608, and 606 and the third-pass flue tubes 638, 636, 634, 632, 630, 628, 626, 624, 622, 620, 618, 616, 614, and 640. As described with respect to FIG. 9B, the gasket 714 can be positioned in gasket track 952 between the flue cover 708 and the tank cover plate 712 to provide a more reliable seal between the flue cover 708 and the tank cover plate 712.

Because the flue tubes of the heat exchanger 602 are matched with respective holes of the tank cover plate 712, horse-shoe-shaped diverter 710 covers the second-pass flue tubes 612, 610, 608, and 606 and the third-pass flue tubes 638, 636, 634, 632, 630, 628, 626, 624, 622, 620, 618, 616, 614, and 640 and defines a top flue structure together with the tank cover plate 712. The horse-shoe-shaped top plenum 702 defines one hot gas flow path from the second-pass flue tubes 612, 610, 608, and 606 to the third-pass flue tubes 638, 636, 634, 632, 630, 628, 626, 624, 622, 620, 618, 616, 614, and 640.

To illustrate, the hot gas is provided by the combustion system 508 through the first-pass flue tube 604, where the hot gas flows to the second-pass flue tubes 612, 610, 608, and 606 and is routed through the horse-shoe-shaped top plenum 702 to the third-pass flue tubes 638, 636, 634, 632, 630, 628, 626, 624, 622, 620, 618, 616, 614, and 640. The hot gas is then transferred to the bottom flue 704 and exits through the hot gas outlet 718.

In some alternative embodiments, the heat exchanger 602 may include fewer or more flue tubes than shown and the tank cover plate 712 may have corresponding number of openings without departing from the scope of this disclosure.

FIG. 10A illustrates a top view of a working example of the horse-shoe-shaped diverter 710 with non-limiting measurements depicted. As depicted in FIG. 10A, in some instances, the screw holes may be disposed on the inner and outer radius of the mounting lip 910 at various angles and distances from the center point of the flue cover 708.

In one instance, let line 1002 be a reference line of angle 0° about a center point 1004 of the horse-shoe-shaped diverter 710. The screw holes 924, 926, 928, 930, 932, 934, 920, and 922 are disposed at angles of 20°, 66°, 115°, 160°, 200°, 243°, 289°, and 340°, respectively, from the line 1002 about the center point 1004. Further, each of the screw holes 924, 926, 928, 930, 932, 934, 920, and 922 are disposed at an outer radius 1006, from the center point 1004, of about 12.8 inches.

In this instance, the screw holes 938, 940, 942, 944, 946, and 936 are disposed at angles of 0°, 66°, 115°, 180°, 243°, and 289°, respectively, from the line 1002 about the center point 1004. Each of the screw holes 938, 940, 942, 944, 946, and 936 are disposed at an inner radius 1008, from the center point 1004, of about 6.8 inches.

It should be noted that any number of screw holes may be used herein. More so, the screw holes may be disposed at any radius and angle about the horse-shoe-shaped diverter.

In this instance, the semicircular portion 902 has an outer radius 1010, from the center point 1004, of about 13.3 inches, and an inner radius 1012, from the center point 1004, of about 6.5 inches.

FIG. 10B illustrates a bottom view of the working example of horse-shoe-shaped diverter 710 with non-limiting measurements depicted. As depicted in FIG. 10B, let line 1014 be a reference line of angle 0° about the center point 1004 of the horse-shoe-shaped diverter 710. In some instances, the bump-outs 964, 958, 960 and 952, which locally enlarge the horse-shoe-shaped plenum 702 to receive the slightly larger in diameter second-pass flue tubes 612, 610, 608, and 606, respectively, may be located at 28°, 152°, 208°, and 332° degrees, respectively. The bump-outs may be any suitable size, shape, or configuration to accommodate the second-pass flue tubes.

Further, in this instance, each of the divots 948 and 950 have a curvature corresponding to a radius of about 0.5 inches.

In some instances, the horse-shoe-shaped diverter 710 includes a basic dimension of about 26.6 inches. The horse-shoe-shaped diverter 710 can be any suitable size, shape, or configuration. The horse-shoe-shaped diverter 710 can be scaled for larger or smaller heat exchanger systems.

FIG. 11A illustrates a cross-sectional view of horse-shoe-shaped diverter 710 of FIG. 10A as cut along a line A-A. FIG. 11B illustrates a detailed view of a portion 1102 of FIG. 11A, showing the non-limiting measurements of the gasket track 952. For example, in some instances, the first protrusion 954 and the second protrusion 956 may be spaced apart by about 0.448 inches. In addition, the first protrusion 954 may include a length of about 0.687 inches, and the second protrusion 956 may include a length of about 0.775 inches.

The first protrusion 954 and the second protrusion 956 may include rounded inner corners at their respective bottom edges. For example, in some instances, the first protrusion 954 may include a rounded inner corner 1104 having a radius of curvature of about 0.070 inches, whereas the second protrusion 956 may include a rounded inner corner 1106 having a radius of curvature of about 0.060 inches. Further, in some instances, the distance from a surface 1108 of the mounting lip 910 to a base 1110 of the gasket track 952 may be about 0.502 inches.

FIG. 11C illustrates a detailed view of horse-shoe-shaped diverter 710 of FIG. 10B as cut along a line B-B, showing the non-limiting measurements of the bump-out 958. For example, the semicircular portion 902 may have a cross-sectional distance 1112 of about 3.501 inches, whereas the bump-out 958 may have a cross-sectional distance 1114 of about 4 inches. The bump-outs may be any suitable size, shape or configuration. As depicted in FIG. 11C, the overall height of the horse-shoe-shaped diverter 710 may be about 2.075 inches. Further, a distance from the top of the first protrusion 954 to the adjoining surface 1112 of mounting lip 910 may be about 0.498 inches.

The dimensions shown in FIGS. 11A-11C are for illustrative purposes. The horse-shoe-shaped diverter 710 may be any suitable size, or configuration.

A method 1200 of heating water in accordance with aspects of the present disclosure will now be described in greater detail with reference to FIG. 12. As depicted in FIG. 12, the method 1200 starts (S1202), and water is provided (S1204). For example, as discussed above with reference to FIG. 5, unheated water enters the water tank 502 through the water inlet 512.

Returning to FIG. 12, after water is provided (S1204), hot fluid is provided (S1206). For example, as discussed above with reference to FIGS. 5-7, gas is heated by the combustion system 508 and is provided into the multi-pass heat exchanger 602 via pipe 716. It should be noted that in the embodiments discussed above, a hot gas is provided. However, in accordance with aspects of the present disclosure, any heated fluid may be used.

Returning to FIG. 12, after hot fluid is provided (S1206), the water is heated (S1208). For example, as shown in FIG. 6, water is filled in the water tank 502. Hot air is passed downward toward the bottom of the water heater 500 through the first-pass flue tube 604, which heats the water surrounding the first-pass flue tube 604 via conduction. By heating the water surrounding the first-pass flue tube 604, the hot air in the first-pass flue 604 is cooled somewhat as it passes through.

The somewhat-cooled hot air from the first-pass flue tube 604 is then passed upward through the second-pass flue tubes 606, 608, 610, and 612, each of which additionally heats the water surrounding the respective second-pass flue tubes 606, 608, 610, and 612. Again, by heating the water surrounding the second-pass flue tubes 606, 608, 610, and 612, the somewhat-cooled hot air is then further cooled.

The further cooled hot air from the second-pass flue tubes 606, 608, 610, and 612 is diverted by the single horse-shoe-shaped top plenum 702 and into the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640.

The further-cooled hot air from the second-pass flue tubes 606, 608, 610, and 612, is then passed downward toward the bottom of the water heater 500 through the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640, each of which additionally heats the water surrounding the respective the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640. Again, by heating the water surrounding the third-pass flue tubes 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, and 640, the further-cooled hot air is then still further cooled.

Accordingly, a portion of water in the water heater 500 that is surrounding the flue tubes is heated by conduction via the multiple passes of the hot air through the multiple flue tubes. The remainder of the water in the water heater 500 is heated via a combination of conduction with the heated water and convection. However, as shown in FIG. 6, the volume within the water tank as shown by areas 644 and 646 have third-pass flue tubes therein. As such, the volume of the columns of water in within the water tank as shown by areas 644 and 646 are heated via conduction from conduction from the third-pass flue tubes. This increases the thermal efficiency of the hot water heater 500 over the hot water heater 100 discussed above with reference to FIG. 2.

Returning to FIG. 12, after the water is heated (S1208), method 1200 stops (S1210).

A water heater in accordance with aspects of the present disclosure includes a multi-pass heat exchanger that has a top plenum that provides a first hot gas flow path from a set of second-pass flue tubes to a set of third-pass flue tubes, wherein the set of second-pass flue tubes comprises an integer number n flue tubes, wherein the set of third-pass flue tubes comprises an integer number m flue tubes, and wherein m>2*n. In other words, the number of third-pass flue tubes are greater than twice the number of second-pass flue tubes. This is to be contrasted with the water heater as discussed above with reference to FIG. 2, wherein each second-pass flue tube is adjacent to two respective third-pass flue tubes. Therefore, in the water heater as discussed above with reference to FIG. 2, a number m third-pass flue tubes is equal to two times a number n second-pass flue tubes.

Because the water heater in accordance with the present disclosure includes a single, horse-shoe-shaped plenum and a set of second-pass flue tubes that comprises an integer number n flue tubes, and a set of third-pass flue tubes that comprises an integer number m flue tubes, and wherein m>2*n, the thermal efficiency is increased as more areas within the water tank are filled with flue tubes as discussed above with reference to FIG. 6.

It should be apparent that the foregoing relates only to certain embodiments of the present application and that numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the disclosure.

Although specific embodiments of the disclosure have been described, numerous other modifications and alternative embodiments are within the scope of the disclosure. For example, any of the functionality described with respect to a particular device or component may be performed by another device or component. Further, while specific device characteristics have been described, embodiments of the disclosure may relate to numerous other device characteristics. Further, although embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that the disclosure is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as illustrative forms of implementing the embodiments. Conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments could include, while other embodiments may not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments.

Claims

1. A water heater comprising:

a top water outlet;

a water tank;

a top cover assembly having a top surface, wherein the top water outlet is disposed on the top surface to output water from the water tank;

a multi-pass heat exchanger positioned in the water tank, wherein the multi-pass heat exchanger comprises flue tubes; and

a top plenum disposed at a top end portion of the water heater, wherein the top plenum comprises a single horse-shoe-shaped plenum.

2. The water heater of claim 1,

wherein the multi-pass heat exchanger includes a first-pass flue tube, a second-pass flue tube, and a third-pass flue tube,

wherein the first-pass flue tube is configured to pass hot air to the second-pass flue tube,

wherein the second-pass flue tube is configured to pass the hot air from the first-pass flue tube to the top plenum, and

wherein the top plenum is configured to divert the hot air from the second-pass flue tube to the third-pass flue tube.

3. The water heater of claim 2,

wherein the first-pass flue tube is centrally disposed within the water tank,

wherein the second-pass flue tube is radially disposed from the first-pass flue tube, and

wherein the third-pass flue tube is radially disposed from the first-pass flue tube and is adjacent to the second-pass flue tube.

4. The water heater of claim 3, further comprising:

a second second-pass flue tube radially disposed from the first-pass flue tube; and

a second third-pass flue tube radially disposed from the first-pass flue tube,

wherein the third-pass flue tube is additionally adjacent to the second third-pass flue tube, and

wherein the second third-pass flue tube is additionally adjacent to the second second-pass flue tube.

5. The water heater of claim 3, further comprising:

a second third-pass flue tube radially disposed from the first-pass flue tube,

wherein the second third-pass flue tube is adjacent to the third-pass flue tube, and

wherein the top water outlet is disposed adjacent to the second third-pass flue tube.

6. (canceled)

7. The water heater of claim 1, further comprising:

wherein the multi-pass heat exchanger includes a plurality of second-pass flue tubes, and a plurality of third-pass flue tubes,

wherein the plurality of second-pass flue tubes includes the second-pass flue tube,

wherein the plurality of third-pass flue tube includes the third-pass flue tube,

wherein the plurality of second-pass flue tubes includes a number n second-pass flue tubes,

wherein the plurality of third-pass flue tubes includes a number m third-pass flue tubes, and

wherein m≠n.

8. (canceled)

9. The water heater of claim 1, further comprising:

a gasket,

wherein the top cover assembly includes a horse-shoe-shaped diverter mounted to a tank cover plate such that the top plenum is defined by a space between the horse-shoe-shaped diverter and the tank cover plate, and

wherein the horse-shoe-shaped diverter includes a single gasket track configured to receive the gasket.

10. The water heater of claim 9,

wherein the flue tubes include a second-pass flue tube and third-pass flue tube,

wherein the second-pass flue tube has a first diameter and the third-pass flue tube has a second diameter that is less than the first diameter,

wherein the single gasket track includes a bump-out having an increased cross-sectional area configured to receive the second-pass flue tube.

11. The water heater of claim 10, wherein the top water outlet is located adjacent to the third-pass flue tube.

12. The water heater of claim 10, further comprising:

a bottom plenum proximal to a bottom end of the water heater,

wherein hot gas enters the bottom plenum from the third-pass flue tube,

wherein the second-pass flue tube and the third-pass flue tube are terminated in the top plenum.

13. (canceled)

14. The water heater of claim 12,

wherein the top cover assembly includes a tank cover plate having tube holes and a water outlet hole,

wherein the tube holes are arranged to match a configuration of the second-pass flue tube and the third-pass flue tube,

wherein the second-pass flue tube and the third-pass flue tube are terminated in the top plenum through the tube holes, and

wherein the water outlet hole is aligned with the top water outlet.

15. The water heater of claim 1, further comprising:

a second third-pass flue tube adjacent to the third-pass flue tube,

wherein a second-pass flue tube is adjacent to the second third-pass flue tube,

wherein the multi-pass heat exchanger includes a first-pass flue tube,

wherein hot gas from a combustion system flows through the first-pass flue tube, and

wherein a portion of the hot gas that flows through the first-pass flue tube flows to the second-pass flue tube.

16. (canceled)

17. The water heater of claim 1, further comprising:

a combustion system attached to a mounting flange,

wherein the flue tubes include a second-pass flue tube and third-pass flue tube,

wherein the top plenum provides a hot gas flow path from the second-pass flue tube to the third-pass flue tube, and

wherein the mounting flange is attached to the top cover assembly.

18. A water heater comprising:

a top water outlet;

a water tank;

a top cover assembly having a top surface, the top water outlet disposed on the top surface to output water from the water tank;

a multi-pass heat exchanger positioned in the water tank, the multi-pass heat exchanger comprising:

a first-pass flue tube;

a set of second-pass flue tubes;

a set of third-pass flue tubes; and

a top plenum at a top end portion of the water heater, the top plenum having a first end and a second end, the first end of the top plenum is separated from the second end of the top plenum so as to define a space, the space including an aperture sized to receive a water outlet pipe through the top water outlet.

19. The water heater of claim 18, further comprising a gasket,

wherein the top cover assembly includes a horse-shoe-shaped diverter mounted to a tank cover plate such that the top plenum is defined by a space between the horse-shoe-shaped diverter and the tank cover plate, and

wherein the horse-shoe-shaped diverter includes a single gasket track configured to receive the gasket.

20. The water heater of claim 19,

wherein each of the set of second-pass flue tubes has a first diameter and each of the third-pass flue tubes has a second diameter that is less than the first diameter,

wherein the single gasket track includes a set of bump-outs, each having an increased cross-sectional area configured to receive a respective one of the set the second-pass flue tubes.

21. The water heater of claim 18, wherein the set of second-pass flue tubes are interspersed with the set of third-pass flue tubes.

22. (canceled)

23. The water heater of claim 18, further comprising a bottom plenum proximal to a bottom end of the water heater,

wherein hot gas from a combustion system flows through the first-pass flue tube to the set of second-pass flue tubes and to the set of third-pass flue tubes,

wherein the hot gas enters the bottom plenum from the set of third-pass flue tubes, and

wherein the top cover assembly includes a tank cover plate that defines the top plenum.

24. (canceled)

25. The water heater of claim 23,

wherein the tank cover plate has tube holes and a water outlet hole, and

wherein the tube holes are arranged to match a configuration of the set of second-pass flue tubes and the set of third-pass flue tubes.

26. A method of heating water, the method comprising:

providing, via water input pipe, un-heated water into a water heater comprising: a top water outlet; a water tank; a top cover assembly having a top surface, the top water outlet disposed on the top surface to output water from the water tank; and a multi-pass heat exchanger positioned in the water tank, the multi-pass heat exchanger comprising a top plenum at a top end portion of the water heater, the top plenum having a first end and a second end, the first end of the top plenum separate from the second end of the top plenum so as to define a space, the space including an aperture sized to receive a water outlet pipe through the top water outlet; and

heating, via the heat exchanger, the un-heated water.

27. (canceled)