Systems and methods for heat pump water heaters with a muffler

Abstract

Systems and methods for a heat pump water heater with an external muffler for reducing noise are provided. The heat pump water heater may include a compressor and other components that may generate a noise during operation. The noise may emanate through air inlet and / or outlets of the heat pump water heater. To reduce the noise emitted from the heat pump water heater, a muffler designed to obstruct and / or absorb soundwaves may be secured to the air outlet and / or air inlet of the heat pump water heater. The muffler may include a cylindrical housing with baffles attached along an interior surface. The baffles may overlap one another such that sound waves are obstructed. The baffles may be perforated for facilitating airflow and / or the cylindrical structure may include a liner for absorbing sound waves. In this manner a heat pump water heater with reduced noise during operation may be achieved.

Description

SYSTEMS AND METHODS FOR HEAT PUMP WATER HEATERS WITH A MUFFLERCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Application Serial No. 63 / 579,678, filed August 30, 2023, the entirety of which is hereby incorporated by reference.TECHNICAL FIELD

[0002] The present disclosure is generally in the field of heat pump water heater systems. For example, systems and methods are provided herein for heat pump water heaters with an external muffler.BACKGROUND

[0003] Heat pump water heater systems have been developed for conveniently and efficiently heating water in residential and commercial settings. Heat pump water heater systems can offer more efficient water heating systems than traditional gas and / or electrical systems. Heat pump water heater systems, such as heat pump water heater 100 of FIG. 1 include first heat exchanger 102, second heat exchanger 104, compressor 106, and one or more expansion valves. The first heat exchanger is typically included together with the compressor in an upper portion or compartment of the heat pump water heater (e.g., upper portion 108). The second heat exchanger is typically included in or adjacent to the water tank (e.g., water tank 1 10) of the heat pump water heater and is used to heat the water within the water tank.

[0004] To facilitate thermal energy exchange between the first heat exchanger and the surrounding environment, the upper portion of the heat pump water heater typically includes an air inlet (e.g., inlet 112) and an air outlet (e.g., outlet 1 14) such that air may flow through the inlet, across the first heat exchanger and out the outlet. A fan may be positioned near the outlet such to encourage airflow across the first heat exchanger. In this manner, the first heat exchanger may exchange thermal energy with the surrounding environment.

[0005] While the heat pump water heater is known to be more efficient than gas and electric water heaters, one challenge with such heat pump water heaters is the noise generated by the compressor and other components of the heat pump water heater, whichmay emanate out of the inlet and / or outlet of the heat pump water heater. Accordingly, there is a need for improved methods and systems for heat pump water heater systems with noise reduction.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 is a schematic illustration of a heat pump water heater in accordance with one or more example embodiments of the disclosure.

[0007] FIGS. 2A-2B are schematic illustrations of a heat pump water heater system including an inlet muffler and an outlet muffler, in accordance with one or more example embodiments of the disclosure.

[0008] FIG. 3A is a schematic illustration of a muffler including overlapping baffles, in accordance with one or more example embodiments of the disclosure.

[0009] FIG. 3B is a cross-sectional view of a muffler including overlapping baffles, in accordance with one or more example embodiments of the disclosure.

[0010] FIG. 4 is a perspective view of a cylindrical housing and a baffle, in accordance with one or more example embodiments of the disclosure.

[0011] FIG. 5 is a cross-sectional view of a muffler including perforated baffles and an interior liner, in accordance with one or more example embodiments of the disclosure.

[0012] FIG. 6 is a schematic illustration of a muffler including a helical baffle arrangement in accordance with one or more example embodiments of the disclosure.DETAILED DESCRIPTION

[0013] Improved heat pump water heater systems have been developed which include an exterior outlet muffler and / or an inlet muffler to obstruct sound waves emanating from the heat pump water heater, thereby reducing noise generated by the heat pump water heater. The heat pump water heater may include heat pump components such as a compressor, an upper heat exchanger, a lower heat exchanger and / or a reversing valve. To reduce noise generated by the compressor and / or other components of the heat pump water heater, a muffler may be attached to the heat pump water heater. The muffler may include a cylindrical body and baffles extending from an interior surface of the cylindrical body- designed to obstruct sound waves as they emanate from the heat pump water heater. It is understood that other shapes (e g., rectangular, hexagon, octagon, etc.) may be used instead.

[0014] Referring now to FIGS. 2A-2B, a heat pump water heater system having an external inlet muffler and an outlet muffler are illustrated. FIG. 2A illustrates a wireframe view of the heat pump water heater system with the external mufflers and FIG. 2B illustrates a perspective view of the heat pump water heater system. While both an inlet muffler and an outlet muffler are illustrated in FIGS. 2A and 2B, it is understood that only an inlet muffler or an outlet muffler may be used. Alternatively, one of the of the inlet muffler and the outlet muffler may be positioned inside the upper compartment housing of the heat pump water heater.

[0015] As shown in FIGS. 2A-2B, upper compartment 200 may be an upper compartment or portion of a heat pump water heater, which may have the same or similar components as heat pump water heater 100 of FIG. 1. It is understood that a muffler may similarly be attached to heat pumps having a heat exchanger elsewhere on the heat pump, other than the upper compartment. The heat pump water heater may include a lower compartment 205 below upper compartment 200, which may be a lower compartment or portion and may include a water tank and the lower heat exchanger, which may be a set of coils through which fluid (e.g., refrigerant) may flow. The water tank and lower heat exchanger may be the same as or similar to heat exchanger 104 and water tank 110 of FIG. 1. The lower heat exchanger may exchange thermal energy with the water in the tank to heat the water in the tank.

[0016] The lower heat exchanger may be connected to compressor 204, which may be any suitable compressor for heat pump water heaters capable of compressing the fluid (e.g., refrigerant) and circulating the fluid throughout the heat pump water heater. The compressor may also be connected to heat exchanger 202 which may similarly be a set of coils through which the fluid may traverse for thermal energy transfer with the surrounding environment. Heat exchanger 202 may connect to the lower heat exchanger via one or more expansion valves.

[0017] Upper compartment 200 may include a housing 201 which may be metallic, plastic, or any other suitable material. Housing 201 may include inlet 206 and outlet 208. Inlet 206 and / or outlet 208 may be one or several through holes, cuts, or perforations through which air in the surrounding environment may enter inlet 206 and exit outlet 208. Inlet 206 may be positioned on one side (or top) of heat exchanger 202 and outlet 208 may be positioned on another side (or top) of heat exchanger 202 such that air may enter inlet 206, flow through heat exchanger 202, and exit outlet 208. It is understood that themuffler may be used with inlets and / or outlets positioned on different areas of the heat pump that those shown in FIG. 2.

[0018] As inlet 206 and outlet 208 may interface with the surrounding environment, sound, pressure and / or vibration waves generated by the heat pump water heater in upper compartment 200 may emanate or otherwise escape through inlet 206 and / or outlet 208. For example, sound and / or vibration generated by compressor 204 and / or any other components of in upper housing 200 or elsewhere on the heat pump water heater may emanate out of inlet 206 and / or outlet 208.

[0019] To reduce noise and / or vibration emitted from inlet 206 and / or outlet 208. muffler 220 may be positioned adjacent to inlet 206 and / or muffler 230 may be positioned adjacent outlet 208. Muffler 220 and / or muffler 230 may be cylindrical in shape and may include a set of baffles. For example, muffler 220 and / or muffler 230 may be the same as or similar to any muffler in FIGS. 3A-7. Muffler 220 and / or muffler 230 may be designed to obstruct and / or buffer sound waves, pressure waves, and / or vibration waves, such that any sound waves, pressure waves, and / or vibration waves exiting muffler 220 and / or muffler 230 have a reduced noise level (e.g., lower decibels) than those exiting inlet 206 and / or outlet 208. For example, the muffler may reduce sound by 1 to 5 decibels.

[0020] As show n in FIGS. 2A-2B, muffler 220 may be connected to inlet 206 via connector 225. Connector 225 may have two open ends. One open end may be secured to a bottom opening of muffler 220 and another open end may be secured to housing 201 and / or inlet 206. The open end secured to the inlet 206 and / or housing 201 may be larger than the open end secured to muffler 220 and may completely cover inlet 206 such that air entering inlet 206 must travel through muffler 220 first.

[0021] Similarly, muffler 230 may be connected to outlet 208 via connector 235. Connector 235 may have two open ends. One open end on the right hand side in FIG. 2B and another open end may be secured to housing 201 and / or outlet 208 (e.g., at the left hand side). The open end secured to the outlet 208 and / or housing 201 may be larger than the open end secured to muffler 230 and may completely cover outlet 208 such that air exiting outlet 208 must travel through muffler 230.

[0022] It is understood that connector 225 and / or connector 235 may be metallic, plastic, and / or any other suitable material. Alternatively, muffler 220 may be connected directly to inlet 206 and / or muffler 230 may be connected directly to outlet 208 such that connector 225 and / or connector 235 may not be needed. For example, the bottom openingof muffler 220 may be sized similarly to inlet 206 and / or the bottom opening of muffler 230 may be sized similarly to outlet 208. In one example, muffler 220 and / or muffler 230 may have a shape different than a cylinder (e.g., non-uniform oblong-type shape, rectangular, octagon, hexagon, etc.).

[0023] Referring now to FIG. 3, a perspective view of an exemplary heat pump water heater muffler is illustrated in accordance with one or more example embodiments of the disclosure. As show n in FIG. 3, muffler 300 may be an external muffler for a heat pump water heater and / or may be connected either directly or indirectly (e g., via a connector) to an inlet or outlet (e.g., air vent) of the heat pump water heater. For example, muffler 300 may be the same as or similar to muffler 220 and / or muffler 230 of FIG. 2.

[0024] Muffler 300 may include cylindrical housing 302 which may be a hollow cylindrical structure. For example, the height of the cylindrical housing may be 5 inches to 15 inches, such as about 7 inches to about 12 inches, about 8 inches to about 10 inches, etc. The wall thickness may be 0.05 inches to 0.3 inches, such as about 0. 1 inches to 0.25 inches, about 0. 15 inches to 0.2 inches. Cylindrical housing 302 may include upper portion 304 and lower portion 306. Upper portion 304 may have a smaller exterior and / or interior diameter as compared to the exterior and / or interior diameter of lower portion 306. For example, the outer diameter of the lower portion may be larger than the outer diameter of the upper portion by 0.025 to 0.3 inches, such as about 0.5 to 0.2 inches, about 0. 1 to 0. 15 inches, etc. Lower portion 306 may be longer in length (e.g., axial length). Upper portion 304 may include through holes 310 and lower portion 306 may include through holes 312.

[0025] Upper portion 304 may optionally be designed to connect to a duct, such as any suitable air duct, for example via through holes 310. Lower portion 306 may optionally be designed to connect to a connector such as connector 225 and / or connector 235 of FIG. 2 via through holes 312. Alternatively, lower portion 306 may connect to an air inlet or outlet of the heat pump water heater. Upper portion 304 and lower portion 306 may be connected via bevel 308. It is understood that the muffler may alternatively be any other cylindrical or other shape and may include a constant inner and / or outer diameter.Ducting may be desirable when the heat pump is in a small space. Alternatively, it may be desirable to use ducting to guide air from a condition space. However, it is understood that the muffler may not be connected to any ducting.

[0026] Lowber portion 306 may be connected to baffles (e g., baffles 320, 322, 324, 326, 328). While five baffles are shown in FIG. 3, it is understood that additional or fewerbaffles may be included in muffler 300. Each baffle may be a semi-circular shape and / or may have a length longer than the length of the radius of muffler 300. Alternatively, baffles may have any other shape and / or size suitable for obstructing sound, vibration, and / or pressure waves. For example, a rectangular muffle may have rectangular shape. Alternatively, a cylindrical muffler may have baffles having a crescent shape.

[0027] In the alternating baffle pattern illustrated in FIG. 3, each baffle is coupled to cylindrical housing 302 along a circumferential edge and is distanced by offset amount 330 in the axial direction (e.g., along a longitudinal axis of the of cylindrical housing 302) from neighboring baffles, thereby spacing the baffles apart along cylindrical housing 300. Additionally, the baffles may be positioned in alternating fashion such that each baffle overlaps a portion of another baffle. For example, as shown in FIG. 3, baffle 326 overlaps baffle 328 by overlap amount 332 and each consecutive baffle may be positioned opposite the baffle that came before it.

[0028] Referring now to FIG. 3B, a cross-sectional view of a muffler 300 is illustrated. As shown in FIG. 3, baffles 320, 322, 324, 326, and 328 are axially offset from one another by the same offset amount (e g., offset amount 330) and have a parallel planer orientation such that each baffle is oriented along a plane parallel to each other baffle. Additionally, each of baffles 320, 322, 324, 326 and 328 overlap another one of baffles 320, 322, 324, 326 and 328 by the same overlap amount (e.g., overlap amount 332). For example, baffles may overlap by 0.1 to 3 inches, such as about 0.5 to 2 inches, about 0.1 to 0. 15 inches, etc. It is understood that the axial distance between baffles and / or the overlap amount may alternatively vary.

[0029] As shown in FIG. 3B, baffles may be arranged in an alternating pattern. For example, a first baffle may be coupled to a right-hand side of cylindrical housing 302 and a second baffle may be axially offset from the first baffle and coupled to a left-hand side of cylindrical housing 302. The next baffle may then follow the pattern and may be coupled again to the right-hand side of cylindrical housing 302 and may be axially offset from the previous baffle and so on. In this manner the repeating pattern may continue within the cylindrical housing.

[0030] Muffler 300 may be the same for both the inlet muffler of the heat pump water heater (e.g.. muffler 220 of FIG. 2) and the outlet muffler (e.g., muffler 230 of FIG. 2) or may be different. For example, offset amount 330 and / or overlap amount 332 may be different for the inlet muffler as compared to the outlet muffler. Additionally, oralternatively, the baffle number, shape, size, thickness, material type, baffle orientation and / or pattern may be different for the inlet muffler as compared to the outlet muffler. In one example, the baffles and / or housing may be made from plastic. Alternatively, in another example, the housing and / or baffle may be made from metal.

[0031] Referring now to FIG. 4, a cylindrical housing of a muffler for a heat pump water heater is illustrated along with a baffle in accordance with one or more example embodiments of the disclosure. Cylindrical housing 400 may be the same as or similar to cylindrical housing 300 of FIGS. 3A-3B. Cylindrical housing 400 may be a hollow cylindrical structure. In one example, cylindrical housing 400 may be an integral structure. Alternatively, upper portion 402 and lower portion 404 may be two different pieces that may be connected together.

[0032] Cylindrical housing 400 may include slots (e.g., slots 410, 412, 414, 416 and 418), which may be cut through portions through a wall of cylindrical housing 400. Slots may be linear voids and may be sized to receive a baffle (e.g., baffle 450). As shown in FIG. 4, baffle 450 may be a semi-circular shape which may have length 452 which may be longer than a radius of an open end of lower portion 404 of cylindrical housing 400.

[0033] Slots in cylindrical housing 400 may be arranged in the baffle pattern illustrated in FIG. 3B, for example. As shown in FIG. 4, slots 410, 412, 414, 416 and / or 418 may be arranged such that every other slot is on a right-hand side of cylindrical housing 400 and each intermittent slot may be positioned on the left-hand side of cylindrical housing 400. While five slots are shown in FIG. 4, it is understood a greater number or fewer number of slots may be provided in cylindrical housing 400.

[0034] Baffles (e.g., baffle 450) may be inserted into a respective slot (e.g., slot 414) and may be connected to or secured to such slot along a circumference edge of the baffle. For example, edge 454 may be secured to cylindrical housing 400 at slot 414 via any suitable technique (e.g., glue, tape, welding, any other adhesive etc.). While the alternating baffle pattern of FIG. 3B is illustrated in FIG. 4, it is understood that any other pattern may be used (e.g., the helical baffle pattern of FIG. 6).

[0035] Referring now to FIG. 5, a cross-sectional view of a muffler including perforated baffles and an interior liner is illustrated in accordance with one or more example embodiments of the disclosure. Muffler 500 may be similar to muffler 300 of FIG. 3A. For example, muffler 500 may be the same as muffler 220 which may bepositioned at an air inlet of the heat pump water heater and / or muffler 230 which may be positioned at an air outlet of the heat pump water heater.

[0036] While baffles may be intended to obstruct and / or absorb sound waves, pressure waves, vibration waves, and the like, it may be desirable to achieve a certain amount of airflow through the inlet and / or outlet of the heat pump water heater. To simultaneously reduce noise emitting from the heat pump water heater and achieve a desired airflow in the inlet and / or outlet, baffles 502 may include perforations 504 along baffles 502 to permit airflow through the perforations.

[0037] Perforations 504 may be several through holes extending through each baffle of muffler 500. It is understood that any suitable perforation size and / or shape may be used. For example, perforations may be rectangular slots instead. It is also understood that only a portion of baffle 504 may include perforations 504 and / or that the distribution of perforations 504 may be non-uniform. It is further understood that one or more perforation may vary in size and shape from the others. For example, circular, semicircular, or triangular perforations may be used. In one example a circular perforation may be used with a diameter of 0. 1 to 0.5 inches, such as about 0.2 to 0.45, about 0.25 to 0.375. etc.

[0038] Muffler 500 may further include liner 506 which may absorb pressure, sound and / or vibration waves and / or otherwise reduce noise. Liner 506 may be any suitable foam or insulation for example. For example, a foam insulation may be used. Liner 506 may extend along all or a portion of an interior wall of cylindrical housing 508 of muffler 500. Liner 506 may be positioned on both lower portion 510 and upper portion 512 or only along lower portion 510. Liner 506 may optionally be positioned on baffles 502, such as along a bottom surface and / or top surface of the baffle. Perforations 504 may also extend through liner 506.

[0039] Referring now to FIG. 6, a schematic illustration of a muffler including a helical baffle arrangement is depicted in accordance with one or more example embodiments of the disclosure. As shown in FIG. 6, muffler 600 may include cylindrical housing 602 and baffles and may be similar to muffler 300 of FIG. 3 A, but with baffles arranged in a helical pattern. While five baffles are shown in FIG. 6, it is understood that a greater or fewer number of baffles may be included.

[0040] Muffler 600 may include baffles 620, 622, 624, 626, and 628. Each baffle may be axially offset by offset amount 630. While offset amount 630 is the same for all bafflesin FIG. 6, it is understood that offset amount 630 may vary between baffles. Further the baffles may have a parallel planer orientation such that each baffle is oriented along a plane parallel to each other baffle.

[0041] Baffles of muffler 600 (e.g., baffles 620, 622, 624, 626, and 628) may each be rotationally offset from a preceding and / or seceding baffle. For example, baffle 622 may be rotated about cylindrical housing 602 by at rotational amount (e.g., a set angle) while maintaining the same planar orientation. For example, baffles may be rotated between 10 degrees. 20 degrees, 30 degrees, 40 degrees, and / or 45 degrees. When the rotational amount is constant for each successive baffle, a helical pattern may be achieved.

[0042] As shown in FIG. 6 air flow through muffler 600 may be obstructed as it must navigate the helical pattern of baffles. It is understood that baffles 620, 622, 624, 626, and 628 may be the same as or similar to baffle 450 of FIG. 4. Alternatively, any other shape, size and / or thickness for each baffle may be used. It is further understood that the rotational offset and / or axial offset amounts between baffles may be constant or may vary. It is understood that baffles of muffler 600 may optionally have perforations such as perforations 504 of FIG. 5 and / or the cylindrical housing and / or baffles of muffler 600 may optionally include liner 506 of FIG. 5. which may be a foam linear, for example.

[0043] 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 do 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

We claim:

1. A heat pump water heater comprising: a first heat exchanger; a second heat exchanger in fluid communication with the first heat exchanger; a compressor in fluid communication with the first heat exchanger and the second heat exchanger; a housing comprising an upper compartment and a lower compartment, the first heat exchanger and the compressor disposed in the upper compartment, and the upper compartment having an inlet and an outlet; a muffler positioned at the outlet and comprising a cylindrical housing, a first baffle, a second baffle, and a third baffle, the first baffle, the second baffle, and the third baffle disposed in the cylindrical housing and having a parallel planer orientation, the second baffle axially offset from the first baffle by a first amount and partially overlapping the first baffle by a second amount, and the third baffle axially offset from the second baffle by the first amount and partially overlapping the second baffle by the second amount, wherein the muffler is configured to obstruct soundwaves emanating from the upper compartment of the housing.

2. The heat pump water heater of claim 1 , further comprising a fourth baffle and a fifth baffle, the fourth baffle axially offset from the third baffle by the first amount and partially overlapping the third baffle by the second amount, and the fifth baffle axially offset from the fourth baffle by the first amount and partially overlapping the fourth baffle by the second amount.

3. The heat pump water heater of any one of claims 1 to 2, wherein the first baffle, second baffle, and third baffle each have a semi-circular shape.

4. The heat pump water heater of any one of claims 1 to 3, further comprising a second muffler positioned at the inlet of the upper compartment and configured to obstruct second soundwaves emanating from the upper compartment.

5. The heat pump water heater of claim 4, wherein the second muffler comprises a second cylindrical housing, a sixth baffle, a seventh baffle, and an eighth baffle, the sixth baffle, the seventh baffle, and the eighth baffle having a second parallel planer orientation, the seventh baffle axially offset from the sixth baffle by a third amount and partially overlapping the sixth baffle by a fourth amount, and the eighth baffle axially offset from the seventh baffle by the third amount and partially overlapping the second baffle by the fourth amount.

6. The heat pump water heater of any one of claims 1 to 5, wherein the second baffle is rotationally offset by a third amount from the first baffle and the third baffle is rotationally offset by the third amount from the second baffle.

7. The heat pump water heater of any one of claims 1 to 6, further comprising a connector having a first open end and a second open end, wherein the connector is coupled at the first open end to the upper compartment at the outlet and is coupled at the second open end to the muffler.

8. The heat pump water heater of claim 7, wherein the second open end is larger than the first open end.

9. The heat pump water heater of any one of claims 1 to 8, wherein the muffler comprises a foam liner coupled to and extending along an inner surface of the cylindrical housing.

10. The heat pump water heater of any one of claims 1 to 9, wherein the first baffle, the second baffle, and the third baffle are perforated.

11. The heat pump water heater of any one of claims 1 to 10, wherein the cylindrical housing has a first end having a first diameter and a second end having a second diameter different than the first diameter.

12. The heat pump water heater of claim 11, wherein the first diameter is larger than the second diameter.

13. The heat pump water heater of claim 1 1 , wherein the first end of the cylindrical housing is configured to be coupled to the upper compartment and the second end is configured to be coupled to a duct.

14. The heat pump water heater of claim 13, wherein one or more of the first end or the second end of the cylindrical housing has a set of through holes.

15. A muffler for reducing sound generated by a heat pump water heater, the muffler comprising: a cylindrical housing having a first open end with a first diameter and a second open end with a second diameter smaller than the first diameter, the first diameter configured to be coupled to a heat pump water heater, the heat pump water heater having a compressor, an inlet, and an outlet; a first baffle having a semi-circular shape and a first length longer than the length of a radius of the cylindrical housing, the first baffle coupled to the cylindrical housing along a first portion of the first circumference of the first baffle; a second baffle having the semi-circular shape and the first length, the second baffle coupled to the cylindrical housing along a second portion of the second circumference of the second baffle, and the second baffle oriented with respect to the first baffle such that the second baffle overlaps the first baffle by a first amount; a third baffle having the semi-circular shape and the first length, the third baffle coupled to the cylindrical housing along a third portion of the third circumference of the third baffle, and the third baffle oriented with respect to the second baffle such that the third baffle overlaps the second baffle by a second amount, wherein the muffler is coupled to the heat pump water heater at the outlet of the heat pump water heater and is configured to obstruct soundwaves generated by the compressor and emanating out of the outlet.

16. The muffler of claim 15, further comprising a foam liner coupled to and extending along an interior surface of the cylindrical housing, the foam liner configured to absorb the soundwaves.

17. The muffler of any one of claims 15 to 16, wherein each of the first baffle, the second baffle, and the third baffle are perforated.

18. The muffler of any one of claims 15 to 17, wherein the first open end has a first set of through holes configured to secure the muffler to the heat pump water heater via a connector.

19. The muffler of claim 18, wherein the second open end has a second set of through holes configured to secure the muffler to a duct.

20. The muffler of any one of claims 15 to 19, wherein the second baffle is rotationally offset by a third amount from the first baffle and the third baffle is rotationally offset by the third amount from the second baffle.

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