JP7659896B2 - Water heater - Google Patents

Description

This disclosure relates to a water heater.

Patent Document 1 discloses an example of a water heater. The water heater of Patent Document 1 includes an exhaust pipe, a mounting member attached to the inner circumferential surface of the exhaust pipe, and a flap rotatably supported by the mounting member to open and close the exhaust flow path in the exhaust pipe. The water heater of Patent Document 1 is configured with a backflow prevention mechanism that restricts the flap from rotating toward the gas reverse flow side by a closing side stopper provided on the mounting member. The closing side stopper is provided at the upper end of the mounting member, and the flap is supported by the mounting member at a height that is higher than the closing side stopper in the closed position, and operates to abut against the closing side stopper from above.

JP 2020-3148 A

In the water heater disclosed in Patent Document 1, when the flap rotates to close, only the part of the flap that is farthest from the rotation axis collides with the closing stopper, so the speed of the colliding part of the flap tends to increase. If only the part moving at a high speed collides when the flap is closed, the impact sound tends to be a sound that reflects that condition (for example, a harsh high-pitched sound).

This disclosure relates to a water heater equipped with a mechanism for rotating a flap inside an exhaust pipe, and aims to provide a technology that can easily reduce the impact caused by a collision of a part moving at a high speed when the flap is closed.

The water heater according to the present disclosure is
A housing that houses a combustion device that burns gas and a heat exchanger;
An exhaust stack which is a path for discharging combustion exhaust to the outdoors;
a backflow suppression mechanism provided in the exhaust tube to suppress a backflow of gas through the exhaust tube to the housing;
A water heater having
The backwind suppression mechanism includes a mounting member that is attached inside the exhaust stack, a flap that is supported on the mounting member so as to be rotatable about a rotation axis that is offset from the center of the exhaust stack, and a mounting member that is mounted on the mounting member,
the mounting member includes a first support portion that supports one side of the flap in the direction of the rotation shaft, and a second support portion that supports the other side of the flap in the direction of the rotation shaft,
the installation member is installed between the first support portion and the second support portion, and is disposed closer to the rotation axis than the center of the exhaust stack,
the flap has an opening/closing portion that opens and closes at least a region inside the exhaust stack that is closer to a center of the exhaust stack than the rotation shaft,
A receiving portion is provided at an upper end of the installation member to receive the impact of the flap.

The technology disclosed herein relates to a water heater equipped with a mechanism for rotating a flap inside an exhaust stack, and makes it easier to reduce the impact caused by collisions of high-speed parts when the flap is closed.

FIG. 1 is a front view illustrating a water heater according to a first embodiment. FIG. 2 is a front view illustrating the water heater of FIG. 1 with the front panel removed. FIG. 3 is a perspective view showing the vicinity of the exhaust pipe of the water heater of FIG. FIG. 4 is a perspective view that shows a schematic configuration of the backwind suppression mechanism and its vicinity in the water heater of FIG. 1 with the exhaust pipe omitted. FIG. 5 is a perspective view showing a configuration in the vicinity of the backwind suppression mechanism in the water heater of FIG. 1 in a partially enlarged schematic manner with the exhaust pipe omitted. FIG. 6 is a plan view that shows a schematic configuration of the backwind suppression mechanism and its surroundings in the water heater of FIG. 1 . FIG. 7 is a bottom view that shows a schematic configuration of the backwind suppression mechanism and its surroundings in the water heater of FIG. 1 . FIG. 8 is a schematic cross-sectional view showing a cross section of the water heater of FIG. 1 near the exhaust stack.

Below, embodiments of the present disclosure are listed and exemplified. Note that the features [1] to [3] exemplified below may be combined in any compatible combination.

[1] A housing that houses a combustion device that burns gas and a heat exchanger;
An exhaust stack which is a path for discharging combustion exhaust to the outdoors;
a backflow suppression mechanism provided in the exhaust tube to suppress a backflow of gas through the exhaust tube to the housing;
A water heater having
The backwind suppression mechanism includes a mounting member that is attached inside the exhaust stack, a flap that is supported on the mounting member so as to be rotatable about a rotation axis that is offset from the center of the exhaust stack, and a mounting member that is mounted on the mounting member,
the mounting member includes a first support portion that supports one side of the flap in the direction of the rotation shaft, and a second support portion that supports the other side of the flap in the direction of the rotation shaft,
the installation member is installed between the first support portion and the second support portion, and is disposed closer to the rotation axis than the center of the exhaust stack,
the flap has an opening/closing portion that opens and closes at least a region inside the exhaust stack that is closer to a center of the exhaust stack than the rotation shaft,
The water heater further comprises a receiving portion provided at an upper end of the installation member for receiving the impact of the flap.

The water heater described in [1] has a configuration in which an installation member is placed closer to the rotation axis than the center of the exhaust pipe, and a receiving portion (the portion that receives the impact of the flap) is provided at the upper end of this installation member. This configuration reduces the speed of the portion of the flap that hits the receiving portion when it closes. Therefore, this water heater makes it easier to reduce the effects caused by the impact of the portion that moves at a high speed when the flap is closed.

[2] The water heater according to [1], wherein the receiving portion includes a protruding portion that protrudes upward and has an apex that contacts the flap.

The water heater described in [2] can receive the flap with nearly point contact when supported by the installation member.

[3] The first support portion includes a first extension portion extending in a direction intersecting the rotation axis,
The second support portion includes a second extension portion extending in a direction intersecting the rotation axis,
The first extension portion and the second extension portion face each other across the center of the exhaust stack,
The first extension portion includes a first contact portion that contacts the flap,
The second extension portion includes a second contact portion that contacts the flap,
The water heater according to claim [2], wherein when the flap is in contact with the top, the first contact portion and the second contact portion are in contact with the opening and closing portion.

The water heater described in [3] can ensure contact between the top, the first contact portion, and the second contact portion when the flap is closed, allowing for contact at three or more points, which can disperse the effects of a collision.

First Embodiment
The following description relates to a water heater 1 according to the first embodiment.
1. Overall configuration of the water heater 1 Fig. 1 is a front view illustrating the water heater 1 according to the first embodiment. Fig. 2 is a front view illustrating a simplified configuration of the water heater 1 with the front cover 2A and the like removed from the housing 2.

As shown in FIG. 2, the water heater 1 includes a housing 2, a combustion device 3, a heat exchanger 4, an exhaust section 5, a fan 7, and the like. The housing 2 is a box-shaped case made of a metal material, and includes a housing body 2B that is a box-shaped body with an open front, and a front cover 2A (FIG. 1) that is attached and detached to the housing body 2B. The front cover 2A shown in FIG. 1 closes the housing body 2B from the front side. As shown in FIG. 2, the housing 2 houses each component such as the combustion device 3, the heat exchanger 4, the exhaust section 5, and the fan 7. The combustion device 3 is disposed near the center inside the housing 2. The heat exchanger 4 is disposed above the combustion device 3 inside the housing 2. The exhaust section 5 is disposed above the heat exchanger 4 inside the housing 2. The gas distribution unit 10 is disposed between the combustion device 3 and the front cover 2A. The fan 7 is disposed below the combustion device 3 inside the housing 2. In the example shown in FIG. 1 etc., the up-down direction of the water heater 1 is the longitudinal direction of the water heater 1 when viewed from the front as in FIG. 1, and is, for example, the vertical up-down direction when the water heater 1 is installed. In the example in FIG. 1, the up-down direction of the water heater 1 is the direction in which the exhaust pipe 100 extends.

The combustion device 3 is a device that burns gas (fuel gas) supplied through the gas distribution unit 10. The combustion device 3 includes an inner case 3A, a burner unit (not shown), and the like. The inner case 3A is a square box-shaped case that fits inside the housing 2. Inside the inner case 3A, a burner unit group is provided, which is a burner unit that is a flat thick and thin burner arranged in the left and right direction. Each thick and thin burner (not shown) has a thin side inlet and a rich side inlet (not shown) on the top and bottom, which open to the front and through which fuel gas and primary air are introduced, and is equipped at the top with a flame hole section consisting of a central thin flame hole and rich flame holes on both the left and right sides of the central thin flame hole. An ignition discharge electrode, a flame rod for flame detection, and the like are provided on the upper front part of the inner case 3A.

The heat exchanger 4 comprises a metal casing 4A that constitutes its outer shell, and a heat transfer tube (not shown) housed inside this casing 4A. The heat exchanger 4 introduces the combustion exhaust gas from the combustion device 3 and passes it through its interior, where heat is exchanged between the combustion exhaust gas and the water flowing inside the heat transfer tube. The combustion exhaust gas that has passed through the heat exchanger 4 is discharged to the exhaust section 5.

The exhaust section 5 includes an exhaust section main body 5A and an exhaust pipe 100. The exhaust section 5 functions to guide the combustion exhaust gas discharged from the heat exchanger 4 upward and discharge it to the outside of the water heater 1 via the exhaust pipe 100.

Fan 7 is a fan that supplies air for combustion. Fan 7 has a drive unit having a motor, blades, etc., and a supply port that supplies air for combustion, and sends the air for combustion from this supply port toward the combustion device 3. The supply port of fan 7 is fixed near the lower end of the combustion device 3.

The water heater 1 shown in Figures 1 and 2 has a gas inlet 91 to which an external gas pipe is connected, a water inlet 92 to which a water pipe is connected, and a hot water outlet 93 on the underside of the housing 2. The water inlet 92 is an inlet through which water is introduced from a water pipe provided outside the water heater 1. The water introduced into the water inlet 92 is supplied to the heat transfer tube of the heat exchanger 4 via a water supply pipe 115. A part of the water supply pipe 115 is illustrated in Figure 2. The hot water outlet 93 is a hot water outlet that discharges hot water to the outside of the water heater 1. The hot water discharged from the heat transfer tube of the heat exchanger 4 is discharged from the hot water outlet 93 via a hot water outlet pipe 116 connected to the downstream end of the heat transfer tube.

In the water heater 1 shown in FIG. 2, the gas inlet 91 is an inlet through which gas is introduced from a gas pipe provided outside the water heater 1. The gas introduced into the gas inlet 91 is supplied to the gas distribution unit 10 through a gas supply section (not shown) equipped with a main valve, a proportional valve, etc. The gas supplied to the gas distribution unit 10 is distributed to pass through a plurality of holes (not shown) provided in the combustion device 3, and is supplied to the combustion device 3 through these holes. The combustion device 3 burns the gas (fuel gas) supplied into the combustion device 3 through the gas distribution unit 10. The exhaust gas (combustion exhaust gas) generated by the combustion of the gas in the combustion device 3 flows from the combustion device 3 into the heat exchanger 4, passes through the heat exchanger 4, and is discharged from the exhaust section 5 to the outside (outside the water heater 1).

2. Details of the exhaust section 5 The exhaust section 5 shown in Fig. 2 includes an exhaust section main body 5A, an exhaust pipe 100, and a backwind suppression mechanism 90 (Figs. 3 and 8) as shown in Figs. 3 to 8. As shown in Fig. 2, the exhaust section 5 is disposed above the heat exchanger 4. The exhaust section 5 forms an exhaust flow path that discharges the combustion exhaust gas that has passed through the heat exchanger 4 inside the housing 2 and flowed upward to the outside of the housing 2.

As shown in FIG. 2, in the water heater 1, openings are provided at the lower and upper ends of the heat exchanger 4, and the combustion exhaust gas sent from the combustion device 3 toward the opening at the lower end of the heat exchanger 4 flows through the heat exchanger 4 and is discharged upward from the opening at the upper end of the heat exchanger 4.

The exhaust unit main body 5A is disposed above the heat exchanger 4 and is a guide path that guides the combustion exhaust gas that has passed through the heat exchanger 4 toward the exhaust pipe 100. The exhaust unit main body 5A forms a flow path that communicates with the opening at the upper end of the heat exchanger 4, and the combustion exhaust gas discharged upward from the heat exchanger 4 is introduced into the exhaust unit main body 5A through an opening provided at the lower end of the exhaust unit main body 5A.

The exhaust unit body 5A is configured as a hood section in which the flow path narrows as it moves upward. Inside the exhaust unit body 5A, a space is configured through which the combustion exhaust flows, and the combustion exhaust that passes through the heat exchanger 4 and flows upward passes through the internal space of the exhaust unit body 5A and flows toward the exhaust pipe 100. Exhaust-related components may be housed inside the exhaust unit body 5A.

The exhaust pipe 100 is a path for discharging the combustion exhaust gas to the outdoors and is a flow path for guiding the combustion exhaust gas. As shown in FIG. 3, the exhaust pipe 100 is configured in a cylindrical shape. As shown in FIG. 8, the exhaust pipe 100 has a plurality of cylindrical sections 100A, 100B, 100C, and 100D configured as a cylinder centered on a center C1 (see FIG. 8). The plurality of cylindrical sections 100A, 100B, 100C, and 100D are integrally configured in a form connected vertically, and the exhaust pipe 100 has an overall cylindrical shape. The center C1 is the center (central axis) of the plurality of cylindrical sections 100A, 100B, 100C, and 100D included in the exhaust pipe 100. The center C1 is, for example, an axis in the vertical direction. The inner and outer circumferential surfaces of the cylindrical sections 100A, 100B, 100C, and 100D are cylindrical surfaces centered on the center C1.

The exhaust pipe 100 has a flow path for the combustion exhaust gas inside. The combustion exhaust gas that flows upward from the exhaust unit main body 5A passes through the exhaust pipe 100 and is discharged to the space outside the water heater 1. The exhaust pipe 100 is configured so that at least a portion of it is exposed to the outside of the housing 2. In the configuration of Figures 1 and 2, the opening 100Z provided at the upper end of the exhaust pipe 100 is the exit (exhaust port) for the combustion exhaust gas. The combustion exhaust gas that passes through the exhaust pipe 100 is discharged to the outside of the water heater 1 from the opening 100Z (exhaust port). As shown in Figures 1 to 3, most of the area of the exhaust pipe 100, including the vicinity of its upper end (near the opening 100Z, which is the exhaust port), is exposed to the outside of the housing 2.

The opening 100W provided at the lower end of the exhaust tube 100 is an inlet for introducing the combustion exhaust that has flowed through the internal space 80 of the exhaust unit main body 5A into the exhaust tube 100. The inside of the exhaust tube 100 and the inside of the exhaust unit main body 5A are connected, and the combustion exhaust that has flowed through the internal space 80 of the exhaust unit main body 5A enters the exhaust tube 100 through the opening 100W and flows through the space inside the exhaust tube 100 toward the opening 100Z.

The backwind suppression mechanism 90 shown in Figs. 4 to 8 is a mechanism that suppresses the backflow of gas in the exhaust stack 100 shown in Fig. 3 toward the housing 2 (specifically, the flow of gas from the opening 100Z side toward the opening 100W side). The backwind suppression mechanism 90 is provided inside the exhaust stack 100. The backwind suppression mechanism 90 mainly comprises an attachment member 110, a flap 120, and an installation member 130. In Figs. 4 and 5, the exhaust stack 100 is omitted, and the position of the exhaust stack 100 is conceptually indicated by a two-dot chain line 100'.

The mounting member 110 shown in Figs. 4 and 5 is a member that is mounted inside the exhaust tube 100 (see the two-dot chain line 100'). The mounting member 110 includes a main body 118, a first support part 111 that supports one side of the flap 120 in the direction of the rotation axis C2, and a second support part 112 that supports the other side of the flap 120 in the direction of the rotation axis C2. In the example of Figs. 4 and 5, the main body 118 is configured in a semi-cylindrical shape and is configured to be fixed inside the exhaust tube 100. The first support part 111 includes a first extension part 111A that extends from the main body 118 and extends in a direction intersecting the rotation axis C2. The second support part 112 includes a second extension part 112A that extends from the main body 118 and extends in a direction intersecting the rotation axis C2.

4 to 8, both the first extension portion 111A and the second extension portion 112A extend along the direction of an imaginary plane perpendicular to the center C1, specifically, along an imaginary plane perpendicular to the center C1 and including the rotation axis C2. As shown in FIGS. 6 and 7, the mounting member 110 has the first extension portion 111A and the second extension portion 112A facing each other across the center C1 of the exhaust stack 100. The first extension portion 111A includes a first contact portion 111Z that contacts the flap 120. The second extension portion 112A includes a second contact portion 112Z that contacts the flap 120. Both the first extension portion 111A and the second extension portion 112A are configured to extend from the main body portion 118. The first contact portion 111Z is provided on the tip side and upper end side of the first extension portion 111A. In the example of FIG. 4 and FIG. 5, the first contact portion 111Z constitutes the tip and upper end of the first extension portion 111A. The second contact portion 112Z is provided on the tip side and upper end side of the second extension portion 112A. In the example of FIG. 4 and FIG. 5, the second contact portion 112Z constitutes the tip and upper end of the second extension portion 112A. The first contact portion 111Z and the second contact portion 112Z are positioned near the flap 120 when the flap 120 is in the closed position, for example, and are not in contact with the flap 120.

The flap 120 is an opening/closing member that is rotatably supported by the mounting member 110. The flap 120 is generally configured in a plate shape, specifically in a disk shape. The flap 120 can rotate around a rotation axis C2 that is offset from the center C1 of the exhaust tube 100. The flap 120 has a shaft portion 124 and an opening/closing portion 122. The opening/closing portion 122 is configured in a plate shape, specifically in a disk shape. The opening/closing portion 122 is a lid-shaped portion of the flap 120 that has the function of opening and closing the flow path in the exhaust tube 100. The opening/closing portion 122 opens and closes at least the area on the center C1 side of the exhaust tube 100 from the rotation axis C2 in the exhaust tube 100. The shaft portion 124 is a portion that constitutes the rotation axis C2 and is a portion that is rotatably supported by the mounting member 110. In the examples of Figures 4 and 5, the shaft portion 124 is a shaft member that is integrally configured with the opening/closing portion 122. In the examples of Figs. 4 and 5, a part of the first support 111 functions as a bearing that rotatably supports one axial side of the shaft 120, and a part of the second support 112 functions as a bearing that rotatably supports the other axial side of the shaft 120. The rotation axis C2 is an axis that forms the center of rotation of the flap 120. In the examples of Figs. 4 to 8, the rotation axis C2 extends along the plate surface of the flap 120, and the plate surface of the flap 120 and the rotation axis C2 are parallel. In the examples of Figs. 4 to 8, the direction of the rotation axis C2 is a direction that intersects with the vertical direction, and specifically, for example, a direction that is perpendicular to the vertical direction. In the example of Fig. 5, the rotation axis C2 is an axis that passes through the center of the shaft 124, and the direction of the rotation axis C2 is the direction of the shaft 124.

As shown in Figs. 4 and 5, the installation member 130 is installed on the mounting member 110. In the example shown in Figs. 4 and 5, the installation member 130 is installed between the first support portion 111 and the second support portion 112. The installation member 130 extends in a direction intersecting the vertical direction, for example, along a direction perpendicular to the vertical direction. Specifically, one end of the installation member 130 is fixed to the first support portion 111, and the other end is fixed to the second support portion 112. As shown in Figs. 6 to 8, the installation member 130 is disposed closer to the rotation axis C2 than the center C1 of the exhaust pipe 100. The installation member 130 is disposed in a form extending along the rotation axis C2.

As shown in Figures 4, 5, and 6, a receiving portion 132 that receives the impact of the flap 120 is provided at the upper end of the erection member 130. The receiving portion 132 includes a protruding portion 134 that protrudes upward and has an apex 136 that contacts the flap 120. In the example of Figures 4 to 6, the receiving portion 132 is configured by the protruding portion 134, but the receiving portion 132 may include a shape other than a protruding portion. The apex 136 is the portion of the protruding portion 134 that contacts the flap 120.

In this configuration, as shown in Figure 8, the flap 120 can rotate around the rotation axis C2. For example, when the combustion exhaust gas flows from the lower side to the upper side inside the exhaust pipe 100, the flap 120 is displaced to the open position as shown in Figure 8 by the pressure of the combustion exhaust gas. In this state, the vicinity of the mounting member 110 is in an open state (an open state in which gas can easily pass through), and the combustion exhaust gas flows through the mounting member 110 in the open state.

On the other hand, when outside air flows into the exhaust stack 100 from the top to the bottom, the flap 120 is displaced to the closed position as shown by the two-dot chain line in FIG. 8. In this state, the area around the mounting member 110 is closed by the flap 120 and is in a closed state (a closed state in which gas cannot pass through as easily as in the open state), blocking or suppressing the flow of gas from the top to the bottom. When the flap 120 is displaced to the closed position, the flap 120 comes into contact with the top 136 of the receiving portion 132 as shown by the two-dot chain line in FIG. 8. This contact maintains the flap 120 in the closed position.

In addition, the positional relationship between the center C1, the rotation axis C2, and the receiving portion 132 may be such that the rotation axis C2 is closer to the receiving portion 132 than the center C1 of the exhaust stack 100. In this configuration, the receiving portion 132 can be brought into contact with the flap 120 on the side closer to the rotation axis C2, and the speed of the portion in contact with the receiving portion 132 can be further reduced. Conversely, the center C1 of the exhaust stack 100 may be closer to the receiving portion 132 than the rotation axis C2. In this configuration, it becomes easier to reduce the force applied to the receiving portion 132 while reducing the speed of the portion in contact with the receiving portion 132 to a certain extent.

3. Example of Effects The water heater 1 is configured such that the installation member 130 is disposed closer to the rotation axis C2 than the center of the exhaust pipe 100, and the receiving portion 132 (the portion that receives the impact of the flap 120) is provided at the upper end of the installation member 130. Due to this configuration, the speed of the portion that hits the vicinity of the receiving portion 132 when the flap 120 is closed is suppressed. Therefore, this water heater 1 makes it easy to suppress the effects caused by the collision of the portion that moves at a high speed when the flap 120 is closed.

For example, if the installation member 130 is not provided, when the flap is closed, only the part with a high speed (the part that hits the first contact portion 111Z and the second contact portion 112Z) hits the mounting member 110, and problems caused by such collisions (for example, a problem that high-speed collisions are concentrated in some places, a problem that harsh high-pitched sounds are likely to occur) are likely to occur. However, the water heater 1 according to the embodiment described above can support the base side of the flap 120 by the receiving portion 132 of the installation member 130. Specifically, in a normal closing operation in which the flap 120 is displaced from the open position to the closed position, the flap 120 does not contact the first contact portion 111Z and the second contact portion 112Z at the time when it hits the top portion 136, so only the part close to the rotation axis C2 hits the top portion 136. Therefore, it is easy to suppress only high-speed collisions from occurring, and harsh high-pitched sounds are unlikely to occur.

In addition, the configuration of this embodiment may be such that the flap 120 does not always contact the first contact portion 111Z and the second contact portion 112Z when the flap 120 is in the closed position, but when the flap 120 is in the closed position, the first contact portion 111Z and the second contact portion 112Z may contact the flap 120 depending on the situation to regulate the displacement. For example, during product manufacturing or construction, the flap 120 may be in a positional relationship where it does not contact the first contact portion 111Z and the second contact portion 112Z when in the closed position (specifically, a relationship of a nearby position that does not slightly contact the flap 120 below the flap 120 in the closed position), and when the flap 120 shifts (shifts downward) to the closed position due to aging, it may come into contact with the first contact portion 111Z and the second contact portion 112Z. Alternatively, during normal operation when the force that displaces the flap 120 downward when the flap 120 is displaced to the closed position is not so large, the flap 120 does not come into contact with the first contact portion 111Z and the second contact portion 112Z when the flap 120 is displaced to the closed position, but when a strong force that presses the flap 120 downward is applied when the flap 120 is displaced to the closed position or when the flap 120 is in the closed position, the flap 120 may be slightly deformed more than during normal operation and may come into contact with the first contact portion 111Z and the second contact portion 112Z. With this configuration, the first contact portion 111Z and the second contact portion 112Z can prevent the flap 120 from being displaced excessively downward due to aging or the like.

In the water heater 1, the receiving portion 132 includes a protruding portion 134 that protrudes upward and has a top portion 136 that contacts the flap 120. Therefore, when the water heater 1 receives the flap 120 by the installation member 130, it can receive it in a manner close to point contact.

When the flap 120 closes, the water heater 1 can ensure contact between the top 136, the first contact portion 111Z, and the second contact portion 112Z, allowing for contact at three or more points, dispersing the effects of a collision.

In a configuration in which the installation member 130 is not provided (for example, a configuration in which the installation member 130 is omitted from the configuration of FIG. 4), when the flap 120 collides with the first contact portion 111Z and the second contact portion 112Z, there is a concern that large vibrations may occur or continue near the first contact portion 111Z or the second contact portion 112Z, and the sound caused by such vibrations may cause discomfort to the user. However, if the installation member 130 is fixed to the first extension portion 111A and the second extension portion 112A as in this configuration, even if the flap 120 collides with the first contact portion 111Z or the second contact portion 112Z, the vibration of the first extension portion 111A and the second extension portion 112A is suppressed, and the above-mentioned discomfort caused by the vibrations is easily reduced.

<Other embodiments>
The present invention is not limited to the embodiments described above and in the drawings. For example, the features of the above or later described embodiments can be combined in any combination within a range that does not contradict. Furthermore, any feature of the above or later described embodiments can be omitted unless it is clearly stated as essential. Furthermore, the above described embodiments may be modified as follows.

In the embodiment described above, one protrusion is provided on the installation member 130, but multiple protrusions may be provided.

In the embodiment described above, the installation member 130 is provided at a position closer to the rotation axis C22 than the center C1 of the exhaust tube 100, but the installation member 130 may be provided at a position closer to the center C1 of the exhaust tube 100 than the rotation axis C2.

It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered restrictive. The scope of the present invention is not limited to the embodiments disclosed herein, but is intended to include all modifications within the scope of the claims or within the scope equivalent to the claims.

1: Water heater 2: Housing 3: Combustion device 4: Heat exchanger 90: Backwind suppression mechanism 100: Exhaust pipe 110: Mounting member 111: First support portion 111A: First extension portion 111Z: First contact portion 112: Second support portion 112A: Second extension portion 112Z: Second contact portion 120: Flap 122: Opening/closing portion 130: Installation member 132: Receiving portion 134: Protruding portion 136: Top portion C1: Center of exhaust pipe C2: Rotation axis

Claims (3)

A housing that houses a combustion device that burns gas and a heat exchanger;
an exhaust stack which is a path for discharging the combustion exhaust gas that has passed through the heat exchanger to the outdoors;
a backflow suppression mechanism provided in the exhaust tube to suppress a backflow of gas through the exhaust tube to the housing;
A water heater having
The backwind suppression mechanism includes a mounting member that is attached inside the exhaust stack, a flap that is supported on the mounting member so as to be rotatable about a rotation axis that is offset from the center of the exhaust stack, and a mounting member that is mounted on the mounting member,
the mounting member includes a first support portion that supports one side of the flap in the direction of the rotation shaft, and a second support portion that supports the other side of the flap in the direction of the rotation shaft,
the installation member is installed between the first support portion and the second support portion, and is disposed closer to a center of the exhaust stack than the rotation shaft, and closer to a center of the exhaust stack than the rotation shaft,
the flap has an opening/closing portion that opens and closes at least a region inside the exhaust stack that is closer to a center of the exhaust stack than the rotation shaft,
The water heater further comprises a receiving portion provided at an upper end of the installation member for receiving the impact of the flap. The water heater according to claim 1 , wherein the receiving portion includes a protruding portion that protrudes upward and has an apex that contacts the flap. the first support portion includes a first extension portion extending in a direction intersecting the rotation axis,
The second support portion includes a second extension portion extending in a direction intersecting the rotation axis,
The first extension portion and the second extension portion face each other across the center of the exhaust stack,
The first extension portion includes a first contact portion that contacts the flap,
The second extension portion includes a second contact portion that contacts the flap,
The water heater according to claim 2 , wherein the first contact portion and the second contact portion are in contact with the opening and closing portion when the flap is in contact with the top portion.

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