Gas inlet pipeline and gas water heating equipment

Abstract

The utility model belongs to the technical field of fuel gas water heating equipment, and discloses a gas inlet pipeline and the fuel gas water heating equipment, the arrangement of a gradually-expanding section and a gradually-shrinking section in the gas inlet pipeline enables the cross section of the gas inlet pipeline to change repeatedly, so that sound waves are reflected and interfered for multiple times in the gas inlet pipeline; due to the fact that the pipeline extending in the waveform mode has the structural characteristic of repeated bending, multiple times of reflection and interference of sound waves in the pipeline extending in the waveform mode can be caused, in the process, the path and the phase of the sound waves are changed for multiple times, and therefore sound energy is attenuated. The pipeline extending in the wave shape is adopted as the air inlet pipeline, for the same airflow flowing path, the pipeline extending in the wave shape occupies smaller space, the internal space of the gas-fired water heating equipment can be fully utilized, and the requirement of the gas-fired water heating equipment for the installation space is lowered.

Description

Technical Field

[0001] The utility model relates to the technical field of gas water heaters, in particular to an air intake pipe and a gas water heater. Background Art

[0002] The principle of the combustion system of combustion equipment such as gas water heaters and gas wall-mounted boilers is: air and gas are fully mixed in advance in a certain proportion to form a premixed gas, which is then ignited and burned in the burner.

[0003] The aerodynamic noise generated during the operation of combustion equipment is relatively large. After research, it was found that the main source of this noise is the air intake. For this reason, the existing technology proposes to use a variable diameter pipe for the air intake duct. However, in actual application, it was found that although the noise can be reduced to a certain extent, the air intake duct has high requirements for the occupied space, resulting in a larger volume of the combustion equipment and higher requirements for the installation space. Utility Model Content

[0004] One of the technical problems solved by the present invention is to provide an air intake duct that can reduce the space occupied by the air intake duct while meeting the noise reduction requirements.

[0005] The second technical problem solved by the present invention is to provide a gas water heater with low noise and small space occupation.

[0006] The first technical problem mentioned above is solved by the following technical solution:

[0007] An air intake duct includes an air intake duct, wherein the air intake duct is a duct extending in a wave-like shape, and the air intake duct has at least one gradually expanding section and at least one gradually contracting section. Along the airflow direction in the air intake duct, the cross-sectional area of ​​the gradually expanding section gradually increases, and the cross-sectional area of ​​the gradually contracting section gradually decreases.

[0008] Compared with the background technology, the air intake duct of the present invention has the following beneficial effects:

[0009] The arrangement of the gradually expanding and converging sections causes the cross-section of the air intake duct to repeatedly change, causing sound waves to reflect and interfere multiple times within the duct. Due to the repeated bending characteristics of the corrugated duct, sound waves reflect and interfere multiple times within the duct. During this process, the path and phase of the sound waves are repeatedly altered, thereby attenuating the sound energy and reducing noise. The use of a corrugated air intake duct occupies less space along its extension direction for an equivalent airflow path, fully utilizing the internal space of the gas water heater, thereby reducing the size of the gas water heater and reducing the installation space required.

[0010] In one embodiment, the air intake duct includes an air intake end portion and the duct body connected in sequence, and the tapered section is the air intake end portion;

[0011] The pipe body includes at least three pipe parts distributed in sequence along its extension direction. Among any three adjacent pipe parts, the two ends of the middle pipe part are connected to the other two pipe parts through a U-shaped pipe; at least one pipe part is a gradually expanding section.

[0012] In one embodiment, the ratio of the maximum cross-sectional area to the minimum cross-sectional area of ​​the tapered section is K, and the value range of K is 1:0.5 to 1:0.9;

[0013] And / or, the minimum cross-sectional area of ​​the tapered section is smaller than the maximum cross-sectional area of ​​the divergent section.

[0014] In one embodiment, the pipe body further includes a shaped connecting plate. Along the extension direction of the air intake pipe, the shaped connecting plate is provided between two adjacent pipe portions and the pipe portions are connected via the shaped connecting plate.

[0015] In one embodiment, at least one of the tube portions is provided with an air regulating plate, one end of which is rotatably connected to the tube portion via a preset rotating shaft, so that the air regulating plate can be switched between a maximum opening position and a minimum opening position;

[0016] When the air regulating plate is at the maximum opening position, the air regulating plate is arranged along the air flow direction in the air intake duct; when the air regulating plate is at the minimum opening position, the air regulating plate blocks part of the air intake duct.

[0017] In one embodiment, a limiting protrusion is provided in the tube portion where the air regulating plate is provided. The limiting protrusion is located downstream of the preset rotating shaft along the air flow direction in the air intake duct. When the air regulating plate is in the minimum opening position, the air regulating plate abuts against the leeward side of the limiting protrusion.

[0018] In one embodiment, along the air flow direction in the air inlet duct, the pipe portion of the air regulating plate is located downstream of the gradually expanding section.

[0019] In one embodiment, the air intake duct includes two half-tubes with openings facing each other, and the two half-tubes are connected to form the air intake duct;

[0020] One of the half-tubes is provided with a clamping hole, and the other half-tube is provided with a clamping protrusion, and the clamping protrusion is clamped in the clamping hole.

[0021] In one embodiment, the two half-tubes are respectively a first half-tube and a second half-tube, wherein the first half-tube forms a first sealed end at each of two circumferential ends, and the second half-tube forms a second sealed end at each of two circumferential ends;

[0022] The two first sealing ends and the two second sealing ends correspond to each other and contact the ground for sealing.

[0023] The second technical problem mentioned above is solved by the following technical solution:

[0024] A gas water heater comprises the gas inlet pipe described in any one of the above embodiments.

[0025] Compared with the background technology, the gas water heater described in the utility model has the following beneficial effects:

[0026] The gas water heater includes the above-mentioned air intake pipe, which can effectively reduce the noise of the gas water heater during operation by reducing the noise in the air intake process of the air intake pipe; and the above-mentioned air intake pipe can reduce the space occupied by the air intake pipe along the extension direction of the air intake pipe, thereby helping to reduce the internal space occupied by the air intake pipe in the volume of the gas water heater, and reducing the requirements of the gas water heater for installation space. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic structural diagram of the air intake duct provided by an embodiment of the present utility model;

[0028] Figure 2 This is a state diagram of the air intake duct when the air regulating plate provided by the embodiment of the utility model is at the minimum opening;

[0029] Figure 3 This is a state diagram of the air intake duct when the air regulating plate provided by the embodiment of the utility model is at the maximum opening;

[0030] Figure 4 yes Figure 1 A partial enlarged schematic diagram of point A in the middle;

[0031] Figure 5 yes Figure 1 A partial enlarged schematic diagram of point B in the middle.

[0032] In the picture:

[0033] 1. Pipe body; 11. Pipe section; 12. U-shaped pipe; 13. Air volume adjustment pipe;

[0034] 151, first half pipe; 1511, clamping protrusion; 1512, first sealing end; 152, second half pipe; 1521, mounting protrusion; 1522, second sealing end; 1523, sealing protrusion;

[0035] 2. Gas outlet end;

[0036] 31. Air regulating plate; 32. Preset rotating shaft; 33. Position limiting convex portion; 34. Counterweight;

[0037] 4. Molding connecting plate; 41. Sub-molding plate;

[0038] 10. Gradually contracting section; 20. Gradually expanding section. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0040] In the description of this application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0041] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. Throughout this application, unless otherwise specified, "plurality" means two or more.

[0042] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0043] The embodiment of the present invention provides an air inlet pipe and a gas water heater including the air inlet pipe. The gas water heater can be a gas wall-mounted boiler, a gas water heater, etc., which are not specifically limited here.

[0044] like Figures 1 to 3As shown, the air intake duct includes an air intake duct, which is a wave-shaped extending duct. The air intake duct has at least one gradually expanding section 20 and at least one gradually converging section 10. Along the airflow direction in the air intake duct, the cross-sectional area of ​​the gradually expanding section 20 gradually increases, and the cross-sectional area of ​​the gradually converging section 10 gradually decreases.

[0045] The arrangement of the diverging section 20 and the converging section 10 causes the cross-section of the air intake duct to repeatedly change, causing sound waves to reflect and interfere multiple times within the duct. Due to the repeated bending characteristics of the corrugated duct, sound waves are repeatedly reflected and interfered within the duct. During this process, the path and phase of the sound waves are repeatedly altered, thereby attenuating the sound energy and reducing noise. The use of a corrugated duct for the air intake duct allows for a smaller space along its extension direction for an equivalent airflow path. This fully utilizes the internal space of the gas water heater, thereby reducing the size of the gas water heater and reducing the installation space required.

[0046] Specifically, the intake duct sequentially connects the intake end and the duct body 1. The duct body 1 includes at least three tube sections 11 distributed sequentially along its extension direction. Of any three adjacent tube sections 11, the middle tube section 11 is connected to the other two tube sections 11 at both ends via a U-shaped tube 12. Exemplarily, the duct body 1 includes three tube sections 11, i.e., the duct body 1 is an S-shaped duct, with the three tube sections 11 distributed sequentially along the vertical direction. In other embodiments, the duct body 1 may also utilize a corrugated duct with more bends.

[0047] In some embodiments, as Figures 1 to 3 As shown, the air intake end is a tapered section 10; at least one pipe section 11 is a gradually expanding section 20. For example, along the air flow direction in the air intake duct, the pipe section 11 in the middle is the gradually expanding section 20, such as the pipe section 11 in the middle is a tapered pipe.

[0048] In other embodiments, the air inlet end can be set as a gradually expanding section, and at least one pipe portion 11 can be set as a gradually contracting section; the air inlet end can be set as a pipeline with a constant cross-sectional area, and both the gradually expanding section and the gradually contracting section can be set on the pipe body 1; the multiple pipe portions 11 of the pipe body 1 can also be set to alternate between gradually contracting sections and gradually expanding sections.

[0049] In some embodiments, as Figures 1 to 3 As shown, the ratio of the maximum cross-sectional area to the minimum cross-sectional area of ​​the tapered section 10 is K, and the value range of K is 1:0.5 to 1:0.9. This arrangement can prevent the cross-sectional area of ​​the tapered section 10 from changing sharply, causing a sharp increase in the airflow velocity and generating noise.

[0050] It should be noted that K can be any one of 1:0.5, 1:0.6, 1:0.7, 1:0.8, and 1:0.9. For example, K=1:0.8.

[0051] In some embodiments, as Figures 1 to 3 As shown, the minimum cross-sectional area of ​​the tapered section 10 is smaller than the maximum cross-sectional area of ​​the gradually expanding section 20. Through simulation experiments, it was found that such a setting can effectively ensure the sound-absorbing effect of the tapered section 10 and the gradually expanding section 20.

[0052] In some embodiments, as Figure 2 and Figure 3 As shown, the air inlet duct also includes an air outlet end 2, which is used to connect to a fan, which is an exhaust fan. In other embodiments, the fan can also be a blower, with the air outlet of the blower connected to the inlet of the air inlet end.

[0053] At least one of the tube sections 11 is provided with an air damper 31. One end of the air damper 31 is pivotally connected to the tube section 11 via a pre-set rotating shaft 32, allowing the air damper 31 to switch between a maximum and minimum opening position. When the air damper 31 is at its maximum opening, it aligns with the airflow within the intake duct. When the air damper 31 is at its minimum opening, it partially blocks the intake duct.

[0054] For ease of description, the pipe portion 11 where the air damper 31 is mounted is referred to as the air volume regulating pipe 13. The fan generates suction, creating a negative pressure within the intake duct, allowing air to enter the intake duct from the intake end. When the fan operates at low speed, the force exerted by the airflow on the air damper 31 is small, resulting in a smaller intake volume.

[0055] When the fan is operating at a high speed, the airflow exerts a large driving force on the air regulating plate 31, and the air regulating plate 31 will be pushed up and rotate around the preset rotating shaft 32, thereby increasing the opening of the air volume regulating tube 13 and increasing the air intake. If this driving force is large enough, the air regulating plate 31 can be pushed to a horizontal position, so that the air intake reaches a maximum.

[0056] When the driving force of the air flow acting on the air regulating plate 31 decreases, the air regulating plate 31 will gradually rotate downward under the action of its own weight and the counterweight block 34, reducing the opening of the air volume regulating tube 13 and reducing the air intake.

[0057] In some embodiments, a limiting protrusion 33 is provided within the tube portion 11 where the air regulating plate 31 is disposed. When the air regulating plate 31 is at its minimum opening, the air regulating plate 31 abuts against the leeward side of the limiting protrusion 33. This arrangement allows the air regulating plate 31 to rotate under a relatively low force, thereby increasing the opening of the air volume regulating tube 13.

[0058] In other embodiments, the air regulating plate 31 may be at the minimum opening position, and the air regulating plate 31 may be arranged vertically, that is, the limiting protrusion 33 is located directly below the preset rotating shaft 32 .

[0059] Exemplarily, the preset rotating shaft 32 is arranged in the middle of the air volume regulating tube 13 in the vertical direction. In order to ensure that wind still passes through the air volume regulating tube 13 when the air regulating plate 31 is in the minimum opening position, the upper end of the air regulating plate 31 is always spaced apart from the upper inner wall of the air volume regulating tube 13.

[0060] Exemplarily, the air volume regulating tube 13 is a circular tube, and accordingly, the limiting protrusion 33 is an arc-shaped boss extending along the circumference of the air volume regulating tube 13 .

[0061] For example, the air volume regulating tube 13 is arranged horizontally, which is beneficial for the air regulating plate 31 to rotate from the maximum opening position to the minimum opening position by its own weight.

[0062] In some embodiments, as Figure 2 and Figure 3 As shown, a counterweight 34 is provided at one end of the air regulating plate 31 away from the preset rotating shaft 32, which is beneficial for the air regulating plate 31 to return to the minimum opening position under the action of its own weight and the counterweight 34 when the speed of the fan is reduced to a certain level.

[0063] For example, the air regulating plate 31 and the counterweight 34 are integrally formed, eliminating the need for additional connectors and reducing the number of components. In other embodiments, the air regulating plate 31 and the counterweight 34 can be connected by welding, snap-fitting, or fastening.

[0064] In some embodiments, along the airflow direction within the air intake duct, the air volume regulating tube 13 is located downstream of the diverging section 20. Exemplarily, the air volume regulating tube 13 is an S-shaped tube located within the lowest tube portion 11. The middle tube portion 11 of the S-shaped tube is the diverging section 20. The cross-sectional area of ​​the air volume regulating tube 13 is equal to the maximum cross-sectional area of ​​the diverging section 20.

[0065] The aperture of the air volume regulating tube 13 is larger, the air flow is more stable, it is easier to control the opening angle of the air regulating plate 31, and the accuracy of air volume control is higher.

[0066] like Figure 1 and Figure 4 As shown, in order to facilitate the installation of the air regulating plate 31, in some embodiments, the air intake duct includes two half-tubes with openings facing each other, and the two half-tubes are connected to form the air intake duct; the outer wall of one of the half-tubes is provided with a clamping hole, and the other half-tube is provided with a clamping protrusion 1511, and the clamping protrusion 1511 is clamped in the clamping hole.

[0067] This arrangement allows the two half-tubes to be detachable, making it easy to install the air regulating plate 31 inside the air volume regulating tube 13, and making subsequent maintenance more convenient.

[0068] For example, the outer wall of one half-tube is provided with two groups of mounting protrusions 1521 arranged at intervals along its circumference, and the two groups of mounting protrusions 1521 are respectively arranged on opposite sides of the opening of the half-tube, and each group of mounting protrusions 1521 is provided with a plurality of clamping holes arranged at intervals along the axial direction of the half-tube; the outer wall of the other half-tube is provided with clamping protrusions 1511 corresponding to the clamping holes one by one, so as to improve the connection stability between the two half-tubes.

[0069] In other embodiments, both half-tubes may be provided with flanges, and the flanges may be connected via a plurality of fasteners such as bolts distributed along the extension direction of the air intake duct.

[0070] In some embodiments, as Figure 1 and Figure 4 As shown, the two half-tubes are respectively the first half-tube 151 and the second half-tube 152. The first half-tube 151 forms a first sealed end 1512 at both ends of the circumference, and the second half-tube 152 forms a second sealed end 1522 at both ends of the circumference; the two first sealed ends 1512 and the two second sealed ends 1522 correspond to the ground contact seal one by one to ensure the sealing effect at the connection position of the two half-tubes to prevent air leakage.

[0071] For example, a first notch is provided at the connection position between the two circumferential end surfaces and the inner circumferential surface of the first half tube 151, so that first sealed end portions 1512 are formed at the circumferential ends of the first half tube 151; a second notch is provided at the connection position between the two circumferential end surfaces and the outer circumferential surface of the second half tube 152, so that second sealed end portions 1522 are formed at the circumferential ends of the second half tube 152, and the two first sealed end portions 1512 are connected to the two second notches in a one-to-one correspondence, and the two second sealed end portions 1522 are connected to the two first notches in a one-to-one correspondence.

[0072] In some embodiments, as Figure 1 and Figure 4 As shown, a sealing protrusion 1523 is provided on the outer wall of the second half tube 152. The sealing protrusion 1523 and the second sealing end 1522 form a U-shaped opening. In other words, a U-shaped opening is defined on the circumferential end surface of the first half tube 151. When the first sealing end 1512 is inserted into the U-shaped opening, the sealing protrusion 1523 abuts against the outer circumferential wall of the first sealing end 1512, further enhancing the sealing effect.

[0073] When air flows through a corrugated duct, the unconnected ends of two adjacent tube sections 11 are not in contact, making them susceptible to slippage under the impact of the airflow. This can cause airflow sloshing within the corrugated duct and increase noise. To address this, in some embodiments, two adjacent tube sections 11 arranged along the extension direction of the intake duct are connected by a shaped connecting plate 4.

[0074] Specifically, taking the corrugated pipe as an S-shaped pipe as an example, two fixed connecting plates 4 are provided, and any two pipe sections 11 arranged adjacent to each other along the extension direction of the intake pipe are connected by the fixed connecting plates 4. This arrangement can improve the stability between the different pipe sections 11, prevent the airflow from impacting the inner wall of the pipe and causing the corrugated pipe to shake, and reduce noise.

[0075] If the air intake pipe is split into two half pipes, each shaping connecting plate 4 includes two sub-shaping plates 41, and the two sub-shaping plates 41 of each shaping connecting plate 4 correspond one-to-one to the two half pipes, so that each half pipe can be ensured to have good stability.

[0076] In some embodiments, as Figure 1 and Figure 5 As shown, the mounting protrusion 1521 located between two adjacent tube sections 11 along the extension direction of the intake duct is provided on one of the sub-forming plates 41, while the corresponding sealing protrusion 1523 is provided on the other sub-forming plate 41. Exemplarily, the sealing protrusion 1523 is formed on the sub-forming plate 41 by punching, simplifying the processing of the sealing protrusion 1523 and reducing processing costs. In other embodiments, the mounting protrusion 1521 and the sealing protrusion 1523 located between two adjacent tube sections 11 along the extension direction of the intake duct can also be provided independently of the forming connecting plate 4.

[0077] The gas water heater provided by the embodiment of the present invention includes the air intake pipe provided by any of the above embodiments. By reducing the noise in the air intake process of the air intake pipe, the noise during the operation of the gas water heater can be effectively reduced; and the above-mentioned air intake pipe can reduce the space occupied by the air intake pipe along the extension direction of the air intake pipe, thereby helping to reduce the volume of the gas water heater, so as to reduce the requirements of the gas water heater for the installation space.

[0078] In the specific contents of the above-mentioned specific implementation methods, the various technical features can be combined in any non-contradictory manner. In order to make the description concise, not all possible combinations of the above-mentioned technical features are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0079] The specific contents of the above-mentioned specific embodiments only express several embodiments of the present invention. Although the description is relatively specific and detailed, it should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be based on the appended claims.

Claims

1. The air intake duct is characterized in that: The air intake duct is a duct extending in a wave-like shape, and has at least one gradually expanding section (20) and at least one gradually contracting section (10). Along the airflow direction in the air intake duct, the cross-sectional area of ​​the gradually expanding section (20) gradually increases, and the cross-sectional area of ​​the gradually contracting section (10) gradually decreases.

2. The air intake duct according to claim 1, characterized in that: The air intake pipe comprises an air intake end and a pipe body (1) connected in sequence, and the tapered section (10) is the air intake end; The pipe body (1) comprises at least three pipe sections (11) distributed in sequence along its extension direction; in any three adjacent pipe sections (11), the pipe section (11) located in the middle is connected to the other two pipe sections (11) at both ends via a U-shaped tube (12); and at least one of the pipe sections (11) is a gradually expanding section (20).

3. The air intake duct according to claim 2, characterized in that: The ratio of the maximum cross-sectional area to the minimum cross-sectional area of ​​the tapered section (10) is K, and the value range of K is 1:0.5 to 1:0.9; And / or, the minimum cross-sectional area of ​​the tapered section (10) is smaller than the maximum cross-sectional area of ​​the divergent section (20).

4. The air intake duct according to claim 2, characterized in that: The pipe body (1) further comprises a shaped connecting plate (4), and along the extension direction of the air intake pipe, the shaped connecting plate (4) is provided between two adjacently arranged pipe portions (11) and the pipe portions are connected via the shaped connecting plate (4).

5. The air intake duct according to claim 2, characterized in that: An air regulating plate (31) is provided in at least one of the tube portions (11), and one end of the air regulating plate (31) is rotatably connected to the tube portion (11) via a preset rotating shaft (32), so that the air regulating plate (31) can be switched between a maximum opening position and a minimum opening position; When the air regulating plate (31) is at the maximum opening position, the air regulating plate (31) is arranged along the air flow direction in the air intake duct; when the air regulating plate (31) is at the minimum opening position, the air regulating plate (31) blocks part of the air intake duct.

6. The air intake duct according to claim 5, characterized in that: A limiting convex portion (33) is provided in the pipe portion (11) where the air regulating plate (31) is provided. The limiting convex portion (33) is located downstream of the preset rotating shaft (32) along the air flow direction in the air intake duct. When the air regulating plate (31) is at the minimum opening position, the air regulating plate (31) abuts against the leeward side of the limiting convex portion (33).

7. The air intake duct according to claim 5, characterized in that: Along the air flow direction in the air intake duct, the pipe portion (11) of the air regulating plate (31) is located downstream of the gradually expanding section (20).

8. The air intake duct according to claim 6, characterized in that: The air intake duct comprises two half-tubes with openings facing each other, and the two half-tubes are joined together to form the air intake duct; One of the half-tubes is provided with a clamping hole, and the other half-tube is provided with a clamping protrusion (1511), and the clamping protrusion (1511) is clamped in the clamping hole.

9. The air intake duct according to claim 8, characterized in that: The two half-tubes are respectively a first half-tube (151) and a second half-tube (152); the first half-tube (151) has two circumferential ends each forming a first sealed end (1512); the second half-tube (152) has two circumferential ends each forming a second sealed end (1522); The two first sealing ends (1512) and the two second sealing ends (1522) correspond to each other one by one and are sealed in surface contact.

10. Gas water heater, characterized in that: The air intake duct comprises the air intake duct according to any one of claims 1 to 9.

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