water heater

Abstract

To provide a water heater which can prevent erroneous assembly caused by screw-fastening.SOLUTION: A combustion unit 3 of a water heater is formed of a combustion device 4 and a gas supply unit 5, and is assembled in a plurality of steps including a first step and a second step. The combustion device 4 and the gas supply unit 5 are provided with a plurality of screw holes for screw-fastening in each of the first step and the second seat are formed. In addition to the screw holes 52, 54, which are be screw-fastened in the first step, a large number of screw holes are formed in a front wall 28 of the combustion device 4. Identification marks 57, 58 are provided at positions adjacent to the screw holes 52, 54. The identification marks 57, 58 differentiate between the screw holes 52, 54 which should be screw-fastened in the first step and the other screw holes. Since this can clarify screw holes that are used in the same step, erroneous assembly can be prevented when a worker performs screw-fastening.SELECTED DRAWING: Figure 6

Description

Technical Field

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[0001] The present invention relates to a water heater.

Background Art

[0002] Conventionally, a water heater includes a combustion device (see, for example, Patent Document 1). The combustion device includes an inner case, a support member, and a plurality of burner units. The inner case is box-shaped with the front side open. The support member is fixed to the inner surface of the rear wall portion of the inner case by spot welding or the like. The plurality of burner units are attached to the support member in a posture where the thickness direction is the left-right direction, and are supported in the inner case in a side-by-side arrangement in the left-right direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the process of assembling the combustion device, when screwing parts with a plurality of similar screw holes on the same surface, there is a problem that the screw holes to be tightened are mistaken in the same process, resulting in incorrect assembly of the parts. [[ID=三十七]]

[0005] An object of the present invention is to provide a water heater that can prevent incorrect assembly due to screwing.

Means for Solving the Problems

[0006] The water heater according to claim 1 comprises a combustion device for burning gas, a front wall fixed to the upper side of the front of the combustion device, and a plate-shaped gas supply unit fixed to the lower side of the front of the combustion device to which the front wall is fixed, and which supplies gas to the combustion device, wherein the front wall and the gas supply unit are assembled to the combustion device in a plurality of steps, wherein the lower end and both left and right ends of the front wall are fixed to the upper side of the front of the combustion device by screw fastening from the front, the upper end of the gas supply unit is overlapped with the lower end of the front wall from the front and fixed by screw fastening from the front, and the remaining part is fixed to the lower side of the front of the combustion device, and the lower end of the front wall is overlapped with a device-side fixing hole provided on the front of the combustion device and screwed in during the step of fixing the lower end of the front wall to the front of the combustion device in the plurality of steps, 1 The hole and the aforementioned 1 Different from a hole other screw holes and the aforementioned 1 Provided adjacent to the hole, the 1 S hole , provided at the lower end of the front wall The aforementioned other A first mark for distinguishing screw holes is provided, and the upper end of the gas supply unit is provided on the lower end of the front surface of the front wall in the step of fixing the upper end of the gas supply unit to the lower end of the front wall among the plurality of steps. other The screw is placed on top of the screw hole on the wall side corresponding to the screw hole and fastened with a screw from the front. 2 The hole and the aforementioned 2 Different from a hole other screw holes and the aforementioned 2 Provided adjacent to the hole, the 2 S hole , provided at the upper end of the gas supply unit The aforementioned other A second mark to distinguish it from a screw hole and It is characterized by the provision of [a feature].

[0007]

[0008]

[0009]

[0010]

[0011]

Advantages of the Invention

[0012] According to the water heater of claim 1, since the mark is provided on the component, the screw holes used in the same process can be clarified. Thereby, it is possible to prevent the operator from making an assembly mistake when tightening the screws. Also, due to the presence of the mark, for example, work instructions such as "fasten the screw hole with this mark display" can be provided.

[0013] Even if a plurality of similar screw holes are provided at similar positions on the same surface of the component, since the mark is provided, the screw holes to be tightened in the same process can be easily identified.

[0014] The specific screw holes to be tightened in the same process can be easily identified.

[0015]

[0016] Even for components assembled in two or more multi-steps, the work can be carried out without misidentifying the screw holes to be tightened for each step.

[0017]

Brief Description of the Drawings

[0018] [Figure 1] It is a front view of the water heater 1. [Figure 2] It is a perspective view of the combustion unit 3. [Figure 3] It is a front view of the combustion unit 3. [Figure 4] It is a perspective view of the combustion device 4. [Figure 5] It is a front view of the combustion device 4. [Figure 6] It is an exploded perspective view of the combustion unit 3. [Figure 7] It is a view showing the first step. [Figure 8]This is a diagram showing the second step. [Modes for carrying out the invention]

[0019] Embodiments of the present invention will be described below. Unless otherwise specified, the apparatus configurations described below are not intended to be the sole limiting factors, but are merely illustrative examples. The drawings are used to illustrate the technical features that the present invention may employ.

[0020] The configuration of the water heater 1 will be explained with reference to Figures 1 to 3. As shown in Figure 1, the water heater 1 is a latent heat recovery type gas water heater. The water heater 1 includes a combustion unit 3, a primary heat exchanger 6, and a secondary heat exchanger 7, etc., within the housing 2. Note that the cover provided on the front of the housing 2 is omitted in Figure 1.

[0021] As shown in Figures 2 and 3, the combustion unit 3 comprises a combustion device 4 and a gas supply unit 5. The combustion device 4 comprises an inner case 20. The inner case 20 is a rectangular box shape with an open top (see Figure 2). A burner group 25 is housed inside the inner case 20. The burner group 25 consists of multiple enrichment burners and is supported inside the inner case 20 by support members (not shown). The burner group 25 burns a mixture of gas and air to generate combustion exhaust. The burner group 25 consists of multiple enrichment burners. A fan 9 is attached to the bottom of the inner case 20 (see Figure 1). The fan 9 supplies combustion air to the burner group 25.

[0022] As shown in Figure 1, the gas supply unit 5 is formed in a plate shape and fixed to the lower front part of the inner case 20. The gas supply unit 5 distributes and supplies gas to the burner group 25. The specific structures of the combustion device 4 and the gas supply unit 5 will be described later.

[0023] The primary heat exchanger 6 is located at the top of the combustion device 4. The combustion exhaust passes upward through the primary heat exchanger 6. The primary heat exchanger 6 exchanges heat between the combustion exhaust and the water flowing through the heat transfer tubes 6A, recovering sensible heat from the combustion exhaust. The secondary heat exchanger 7 is located at the top of the primary heat exchanger 6. The combustion exhaust that has passed through the primary heat exchanger 6 passes upward through the secondary heat exchanger 7. The secondary heat exchanger 7 exchanges heat between the combustion exhaust and the water flowing through the heat transfer tubes (not shown), recovering latent heat from the combustion exhaust.

[0024] An exhaust pipe 8 is provided on the top surface of the housing 2. The exhaust pipe 8 protrudes upward from the top surface of the housing 2 and discharges the combustion exhaust that has passed through the secondary heat exchanger 7 to the outside of the housing 2. A gas inlet 11, a water inlet 12, and a hot water outlet 13 are provided on the bottom surface of the housing 2. A gas pipe (not shown) is connected to the gas inlet 11. A water pipe (not shown) is connected to the water inlet 12. Piping (not shown) to a hot water tap is connected to the hot water outlet 13.

[0025] Within the housing 2, the gas inlet 11 is connected to the gas supply unit 5 via a gas pipe 19. The gas pipe 19 is equipped with a main valve and a proportional valve, etc. (not shown). The water inlet 12 is connected to the water supply section 14. The water supply section 14 is connected to the inlet of the secondary heat exchanger 7 via a water supply pipe 15. The outlet of the secondary heat exchanger 7 is connected to the inlet of the primary heat exchanger 6 via a relay pipe 17. The outlet of the primary heat exchanger 6 is connected to the hot water outlet 13 via a hot water outlet pipe 18. Bypass pipes 16A and 16B are connected between the water supply section 14 and the hot water outlet pipe 18. The bypass pipes 16A and 16B allow a portion of the water supplied from the water supply section 14 to flow through the hot water outlet pipe 18 without passing through the primary heat exchanger 6 and the secondary heat exchanger 7.

[0026] The structure of the combustion device 4 will be explained with reference to Figures 4 to 6. As shown in Figures 4 and 5, the combustion device 4 comprises an inner case 20 and a burner assembly 10. The inner case 20 comprises a case body 30 and a front wall 28. The case body 30 is a rectangular box shape with the top and front open. The front wall 28 is fixed so as to close the upper front side of the case body 30.

[0027] The structure of the case body 30 will now be described. As shown in Figure 6, the case body 30 comprises a right wall portion 31, a left wall portion 32, a rear wall portion 33, and a bottom wall portion 34. Fixing pieces 35 and 36 are formed at the front ends of the right wall portion 31 and the left wall portion 32, respectively, by bending outwards. A screw hole 351 is provided at the top of the fixing piece 35, a screw hole 352 is provided slightly above the vertical midpoint of the fixing piece 35, and a screw hole 353 is provided below the vertical midpoint of the fixing piece 35. Screw holes 351 to 353 penetrate the fixing piece 35 in the front-rear direction. A screw hole 361 is provided at the top of the fixing piece 36, a screw hole 362 is provided slightly above the vertical midpoint of the fixing piece 36, and a screw hole 363 is provided below the vertical midpoint of the fixing piece 36. The front wall 28 and the gas supply unit 5 are screwed to the fixing pieces 35 and 36.

[0028] An opening (not shown) is provided in the lower left rear portion of the bottom wall portion 34. A fan 9 is fixed so as to cover the opening from below (see Figure 1). Combustion air blown from the fan 9 flows into the case body 30 through the opening. A fixing piece 38 that protrudes upward is provided at the front end of the bottom wall portion 34. The fixing piece 38 is formed in a substantially rectangular shape that extends in the left-right direction when viewed from the front. A screw hole 381 is provided to the right of the midpoint of the fixing piece 38 in the left-right direction, and a screw hole 382 is provided to the left of the midpoint of the midpoint in the left-right direction.

[0029] The structure of the burner assembly 10 will now be described. The burner assembly 10 comprises a burner group 25, a support member (not shown), and a front plate portion 27. The burner group 25 consists of multiple light and dark burners, which are arranged side by side in the left-right direction with their thickness direction being the left-right direction. The support member integrally supports the burner group 25. The front plate portion 27 is attached to the front side of the burner group 25. Multiple pairs of upper and lower openings 271 and 272 are arranged side by side in the left-right direction on the front plate portion 27. The openings 271 and 272 correspond to the light-side inlet (not shown) and the dark-side inlet (not shown), respectively, provided on the front side of the light and dark burners. An upper fixing piece 273 is provided at the upper end of the front plate portion 27. The upper fixing piece 273 is formed in a substantially rectangular shape that is long in the left-right direction when viewed from the front. A screw hole 275 is provided slightly to the right of the left-right center of the upper fixing piece 273, and a screw hole 276 is provided to the left of the left-right center. The burner assembly 10 is inserted into the case body 30 from the front and secured with screws.

[0030] The structure of the front wall 28 will now be described. The front wall 28 is rectangular in shape, elongated in the left-right direction when viewed from the front, and is fixed to close the upper front side of the case body 30. A discharge electrode 55 for ignition and a flame rod 56 as an electrode for flame detection are fixed to the front wall 28 approximately in the left-right direction. Screw holes 41 and 42 are provided at the top and bottom of the right end of the front wall 28, and screw holes 43 and 44 are provided at the top and bottom of the left end. Screw holes 41 to 44 are holes for fixing the front wall 28 to the upper side of the fixing pieces 35 and 36 of the case body 30.

[0031] Six screw holes 45-50 are provided at the lower end of the front wall 28, spaced apart from each other and arranged sequentially from right to left. Between screw holes 46 and 47, two screw holes 51 and 52 are provided side by side, spaced apart. Screw hole 51 is located to the left of screw hole 46, and screw hole 52 is located to the right of screw hole 47 and below the discharge electrode 55. Screw hole 53 is provided to the right of screw hole 49. Screw hole 54 is provided between screw holes 49 and 50.

[0032] These four screw holes 51-54 are smaller than screw holes 45-50 and are the same size and shape as each other. Of these four screw holes 51-54, two screw holes 52 and 54 are the first screw holes that will be fastened in the first step described later. Therefore, an identification mark 57 is engraved to the right of screw hole 52 and adjacent to it, and an identification mark 58 is engraved to the left of screw hole 54 and adjacent to it. Identification mark 57 is in the shape of "<" to indicate screw hole 52 from the right. Identification mark 58 is in the shape of ">" to indicate screw hole 54 from the left. Identification marks 57 and 58 indicate that they are the first screw holes.

[0033] The structure of the gas supply unit 5 will now be described. The gas supply unit 5 comprises a main body portion 60 and a back plate portion 62. The main body portion 60 is formed in a plate shape and comprises a rectangular portion 601 and a downward extension portion 602. The rectangular portion 601 is formed in a roughly rectangular shape that is horizontally elongated when viewed from the front, and a roughly L-shaped notch portion 603 is provided at the lower left corner. The downward extension portion 602 extends downward from the lower right corner of the rectangular portion 601. A convex portion 64 extending in the vertical direction is provided on the front surface of the downward extension portion 602.

[0034] A protruding portion 65 extending in the left-right direction is provided at the lower end of the front surface of the rectangular portion 601. Above the protruding portion 65 on the front surface of the rectangular portion 601, four protruding portions 66 to 69 are provided from right to left. The protruding portions 66 to 69 are formed in a roughly T-shape when viewed from the front, with the left and right protruding portions 66 and 69 being wider in the left-right direction, and the protruding portions 67 and 68 between them being narrower in the left-right direction. These six protruding portions 64 to 69 bulge outwards from the front surface of the main body portion 60.

[0035] An inlet 63 is provided at the lower end of the downward extension 602. The end of the gas pipe 19 is connected to the inlet 63. Inside the downward extension 602, a first gas flow path (not shown) is provided, extending upward from the inlet 63 toward the rectangular section 601. The convex section 64 is provided at a position corresponding to the first gas flow path. Inside the rectangular section 601, a second gas flow path (not shown) is provided, extending to the left from the upper end of the first gas flow path, and four first to fourth gas flow paths (not shown) branch upward from the second gas flow path. The first to fourth gas flow paths are provided in order from right to left. Solenoid valves (not shown) are provided between the second gas flow path and each of the first to fourth gas flow paths. Each solenoid valve opens and closes the passage between the second gas flow path and each of the first to fourth gas flow paths under the control of a control unit (not shown).

[0036] The convex portion 65 is provided at a position corresponding to the second gas flow path. The convex portions 65 to 69 are provided at positions corresponding to the first to fourth flow paths, respectively. Multiple supply ports (not shown) are provided on the rear surface of the rectangular portion 601 to supply the gas that has flowed through the first to fourth flow paths to each concentration burner. The multiple supply ports are provided at positions corresponding to multiple openings 271 and 272 arranged side by side in the left-right direction on the front plate portion 27.

[0037] A screw hole 71 is provided slightly above the vertical midpoint of the right end of the rectangular portion 601. A screw hole 72 is provided in the approximate center of the rectangular portion 601, between the convex portions 66 and 67, and a screw hole 73 is provided between the convex portions 68 and 69. A screw hole 74 is provided slightly to the right of the horizontal midpoint of the upper end of the rectangular portion 601, and a screw hole 75 is provided to the left of the horizontal midpoint. Furthermore, numerous holes 77 are provided in the rectangular portion 601 and the downward extension portion 602. Note that in Figures 6 and 8, although numerous holes 77 are provided in the main body portion 60 of the gas supply unit 5, only one hole is indicated by the reference numeral 77 for clarity.

[0038] The back plate portion 62 is fixed to the rear surface of the main body portion 60 and is formed in a roughly rectangular shape that is elongated in the left-right direction to match the shape of the rectangular portion 601. The left end of the back plate portion 62 protrudes to the left from the left end of the rectangular portion 601. A screw hole 76 is provided in the portion that protrudes to the left, approximately in the center in the vertical direction.

[0039] In the main body 60 of the above configuration, screw holes 71 to 76 are second screw holes that will be fastened with screws in the second step described later. Therefore, an identification mark 81 is engraved to the left of screw hole 71 and adjacent to it, an identification mark 82 is engraved below screw hole 72 and adjacent to it, an identification mark 83 is engraved below screw hole 73 and adjacent to it, an identification mark 84 is engraved to the left of screw hole 74 and adjacent to it, and an identification mark 85 is engraved to the right of screw hole 75 and adjacent to it. Furthermore, an identification mark 86 is engraved to the right of screw hole 76, which is located at the left end of the rectangular portion 601 and adjacent to it, at the left end of the back plate portion 62. Identification marks 81 to 86 indicate that they are second screw holes by positioning one vertex of the "△" shape toward the corresponding screw hole.

[0040] Referring to Figures 6 to 8, the assembly process of the combustion unit 3 will be explained. In this embodiment, the first step of fixing the front wall 28 to the combustion device 4 and the second step of fixing the gas supply unit 5 to the combustion device 4 will be explained.

[0041] The first step will be explained with reference to Figures 6 and 7. With the burner assembly 10 fixed inside the case body 30, the worker positions the front wall 28 on the upper side of the opening front of the case body 30. At this time, the screw holes 41 and 42 on the right end of the front wall 28 correspond to the screw holes 351 and 352 of the right fixing piece 35 of the case body 30, and the screw holes 43 and 44 on the left end correspond to the screw holes 361 and 362 of the left fixing piece 36 of the case body 30. Furthermore, the screw hole 52 of the front wall 28 corresponds to the right screw hole 275 provided on the upper fixing piece 273 of the front plate portion 27, and the screw hole 54 of the front wall 28 corresponds to the left screw hole 276 provided on the upper fixing piece 273 of the front plate portion 27.

[0042] Here, in the front wall 28, the first screw holes to be fastened with screws in the first step are the four screw holes 41-44, plus two screw holes 52. 54 However, at the lower end of the front surface which is on the same plane as the front wall 28, there are two screw holes 52 and 54 In addition, screw holes 45-50, screw holes 51, 53 They are arranged in a mixed pattern in the left-right direction. Therefore, in this embodiment, by checking the identification marks 57 and 58, the worker can identify the screw hole 52 and 54 The first step is to fasten the screws. 1 It's immediately obvious that these are screw holes.

[0043] The worker fastens screws 91-94 to screw holes 351, 352, 361, and 362, respectively, through screw holes 41-44 in the front wall 28. Furthermore, screws 95 and 96 are fastened to screw holes 275 and 276, respectively, through screw holes 52 and 54, identified by identification marks 57 and 58. The first step is completed and the combustion device 4 is finished when the front wall 28 is fixed to the upper part of the opening front of the case body 30 (see Figures 4 and 5). In this way, even if similar holes are located close together and mixed, it is easy to find the screw holes 52 and 54 that should be fastened in the first step, thus preventing incorrect assembly of the front wall 28 to the case body 30 due to mistakes in the screw holes.

[0044] Referring to Figure 8, the second step will be explained. Once the first step is completed, the worker performs the second step. The worker positions the gas supply unit 5 relative to the lower front part of the case body 30 to which the front wall 28 is fixed. At this time, the screw hole 71 of the gas supply unit 5 is opposite to the screw hole 353 of the right fixing piece 35 of the case body 30, the screw hole 72 is opposite to the screw hole 381 of the fixing piece 38 of the case body 30, the screw hole 73 is opposite to the screw hole 382 of the fixing piece 38 of the case body 30, the screw hole 74 is opposite to the screw hole 51 of the front wall 28, the screw hole 75 is opposite to the screw hole 53 of the front wall 28, and the screw hole 76 is opposite to the screw hole 363 of the left fixing piece 36 of the case body 30.

[0045] In this gas supply unit 5, the second screw holes to be fastened in the second step are the six screw holes 71 to 76. However, on the front surface of the gas supply unit 5, which is on the same plane, there are numerous other holes 77 scattered throughout, in addition to these screw holes 71 to 76. Therefore, in this embodiment, by checking the identification marks 81 to 86, the worker can at a glance distinguish that the screw holes 71 to 76 are the second screw holes to be fastened in the second step.

[0046] The worker fastens screws 101-106 to screw holes 353, 381, 382, ​​51, 53, and 363, respectively, through screw holes 71-76 of the gas supply unit 5. The second step is completed when the gas supply unit 5 is fixed to the lower front part of the case body 30, and the combustion unit 3 is completed (see Figures 2 and 3). In this way, even if similar holes are located close together and mixed, it is easy to find the screw holes 71-76 that should be fastened in the second step, thus preventing incorrect assembly of the gas supply unit 5 to the case body 30 and front wall 28 due to mistakes in the screw holes.

[0047] Furthermore, the shapes of the identification marks 57 and 58 indicating the first screw holes and the shapes of the identification marks 81 to 86 indicating the second screw holes are different from each other. As a result, in the combustion unit 3, which is assembled in multiple steps including the first and second steps, even beginners unfamiliar with the process can screw in the first screw holes, which are tightened in the first step, and the second screw holes, which are tightened in the second step, without making a mistake, allowing the work to proceed smoothly.

[0048] Furthermore, since the identification marks 57 and 58 on the front wall 28 and the identification marks 81 to 86 on the gas supply unit 5 are all engraved, it is possible to prevent these identification marks from disappearing from the parts. In addition, since the identification marks can be formed without increasing the pressing process in the manufacturing of the front wall 28 and the gas supply unit 5, it can be implemented at low cost.

[0049] In the above description, screw holes 52 and 54 are the "Phase of the Invention" 1This is an example of a "screw hole". Screw holes 71-76 are the "first" of the present invention. 2 This is an example of a "slotted hole". Identification marks 57 and 58 are examples of the "first mark" of the present invention. Identification marks 81 to 86 are examples of the "second mark" of the present invention.

[0050] As described above, the combustion unit 3 of the water heater 1 in this embodiment consists of a combustion device 4 and a gas supply unit 5, and is assembled in multiple steps, including a first step and a second step. The combustion device 4 and the gas supply unit 5 are provided with multiple screw holes that are fastened with screws at least in each of the first and second steps. For example, the front wall 28 of the combustion device 4 is provided with numerous screw holes in addition to the screw holes 52 and 54 that are to be fastened with screws in the first step. Identification marks 57 and 58 are provided at positions adjacent to the screw holes 52 and 54, respectively. The identification marks 57 and 58 distinguish the screw holes 52 and 54 that are to be fastened with screws in the first step from the other screw holes. This makes it possible to clearly identify the screw holes used in the same step, thus preventing assembly errors when workers fasten screws. In addition, the presence of identification marks 57 and 58 allows for work instructions to be given to workers, for example, "Fasten the screw holes with this mark."

[0051] Furthermore, in the first step, the screw holes 52 and 54 to be screwed can be clearly identified by the identification marks 57 and 58, thus preventing accidental screwing into other screw holes. Also, after the first step, by checking the identification marks 57 and 58 on the front wall 28, it is easy to visually determine whether the screw holes 52 and 54 have been properly screwed and whether any screws have been mistakenly screwed into other screw holes. This allows for the removal of screws from any incorrectly screwed holes and the correct screwing into the intended screw holes 52 and 54 before performing the second step.

[0052] It should be noted that the present invention is not limited to the above embodiments, and various modifications are possible. The identification marks 57 and 58 provided on the front wall 28 and the identification marks 81 to 86 provided on the gas supply unit 5 are all engraved, but they may be provided by other methods, such as printing or attaching identification mark stickers. Also, the shapes of the identification marks 57 and 58 and the identification marks 81 to 86 may differ from those in the above embodiments, as long as the target screw hole can be distinguished from other untargeted screw holes. In addition to symbols as in the above embodiments, arrows or letters may also be used. Since the identification marks 57 and 58 and the identification marks 81 to 86 identify screw holes that are screwed in in separate processes, it is desirable that they have different shapes from each other, but they may be the same. Also, the color of the identification marks may be changed for each process.

[0053] Furthermore, in the above embodiment, for the sake of explanation, the first and second screw holes that are fastened with screws in the first and second manufacturing processes of the combustion unit 3, respectively, and the identification marks provided adjacent to them have been described. However, in other processes as well, it is preferable to provide identification marks adjacent to the screw holes that are fastened with screws in the same process.

[0054] Although water heater 1 is a latent heat recovery type water heater, it may also be a sensible heat recovery type water heater with a single heat exchanger. [Explanation of Symbols]

[0055] 1. Water heater 3 Combustion Unit 4. Combustion device 5. Gas supply unit 20 Inner Cases 28 Front wall 30 Case Body 52, 54 screw holes 57, 58 Identification marks 60 Main body 71-76 screw holes 77 holes 81-86 Identification Mark

Claims

[Claim 1] A combustion device that burns gas, A front wall fixed to the upper side of the front surface of the combustion device, A plate-shaped gas supply unit is fixed to the lower side of the front surface of the combustion device to which the front wall is fixed, and supplies gas to the combustion device. Equipped with, A water heater in which the front wall and the gas supply unit are assembled to the combustion device in multiple steps, The front wall is fixed to the upper side of the front surface of the combustion device by screw fastening from the front, with its lower end and both left and right ends fixed to the upper side of the front surface of the combustion device. The gas supply unit is such that its upper end is superimposed on the lower end of the front wall from the front and fixed by screws from the front, while the remaining portion is fixed to the underside of the front surface of the combustion device. The lower end of the front wall is In the step of fixing the lower end of the front wall to the front surface of the combustion device, among the plurality of steps described above, a first screw hole is provided on the front surface of the combustion device, and the screw is fastened from the front by overlapping it with the device-side fixing hole provided on the front surface of the combustion device, Other screw holes different from the first screw hole, A first mark is provided adjacent to the first screw hole, and is used to distinguish the first screw hole from the other screw holes provided at the lower end of the front wall. A system was established, The upper end of the gas supply unit is In the step of fixing the upper end of the gas supply unit to the lower end of the front wall, among the plurality of steps, a second screw hole is provided that is overlapped from the front with a wall-side screw hole corresponding to the other screw hole provided at the lower end of the front surface of the front wall and fastened with a screw, Other screw holes different from the second screw hole mentioned above, A second mark is provided adjacent to the second screw hole, and is used to distinguish the second screw hole from the other screw holes provided at the upper end of the gas supply unit. The establishment A water heater characterized by the following features.

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