Connection structure between water heater and supply and exhaust pipe

Abstract

To enable connection of a supply and exhaust pipe of different type.SOLUTION: A water heater 1 comprises a connection part 14 in which an outer cylinder 40 for sucking the air into a housing 2 when a fan 15 is driven and an inner cylinder 41 arranged coaxially in the outer cylinder 40 and for exhausting a combustion exhaust gas which has passed through a combustion device 10 are made to protrude upward from an upper surface of the housing 2. To the connection part 14, a first supply and exhaust pipe which coaxially includes a first supply pipe corresponding to the outer cylinder 40 and a first exhaust pipe corresponding to the inner cylinder 41, and a second supply and exhaust pipe which coaxially includes a second supply pipe corresponding to the outer cylinder 40 and having an inner diameter larger than an outer diameter of the first supply pipe and a second exhaust pipe corresponding to the inner cylinder 41 can be connected selectively.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a forced air supply / exhaust type water heater that draws combustion air into the appliance and supplies it to a burner by driving a fan installed inside the appliance, and discharges combustion exhaust gas that has passed through a heat exchanger to the outside. and the connection structure between the intake and exhaust pipes Regarding. [Background technology]

[0002] A water heater comprises a housing containing a combustion device such as a burner, heat exchanger, and fan, and a connection part formed at the top of the combustion device, which includes an inner cylinder that protrudes upward and an outer cylinder that coaxially surrounds the inner cylinder. A separate supply and exhaust pipe is connected to this connection part, which includes an exhaust pipe that extends vertically and an air intake pipe that coaxially surrounds the exhaust pipe. The supply and exhaust pipes are arranged outside the building, with the exhaust pipe communicating with the inner cylinder and the air intake pipe communicating with the outer cylinder (see, for example, Patent Document 1). When the fan inside the housing is driven, outside air is drawn in through the air intake pipe of the intake and exhaust pipe, enters the appliance through the outer tube, and is supplied to the burner as combustion air. The combustion exhaust gas generated by combustion in the burner passes through the heat exchanger for heat exchange, then passes through the inner tube and the exhaust pipe of the intake and exhaust pipe, and is discharged outdoors. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Publication number 7-22593 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned conventional forced supply and exhaust water heater, the connection part is compatible with only one type of supply and exhaust pipe with a specific diameter, and it is not possible to connect a different type of supply and exhaust pipe with a different diameter.

[0005] Therefore, the present disclosure provides a water heater that can connect two types of supply and exhaust pipes with different diameters. and the connection structure between the intake and exhaust pipesThe purpose is to provide the following. [Means for solving the problem]

[0006] In order to achieve the above object, the present disclosure provides a combustion device including a housing for accommodating a combustion device having a fan; an outer cylinder for drawing air into the housing as the fan is driven, and an inner cylinder arranged coaxially within the outer cylinder for discharging the combustion exhaust gas that has passed through the combustion device, and a connecting portion formed by projecting these two cylinders upward from the top surface of the housing. The connection of the water heater , a first intake and exhaust pipe including a first intake pipe corresponding to the outer cylinder and a first exhaust pipe corresponding to the inner cylinder, the first intake and exhaust pipe being coaxial with each other; a second intake and exhaust pipe including a second intake pipe corresponding to the outer cylinder and having an inner diameter larger than an outer diameter of the first intake pipe, and a second exhaust pipe corresponding to the inner cylinder, the second intake and exhaust pipe being coaxial with each other; A connection structure between a water heater and an intake and exhaust pipe that can be selectively connected is. and, the first air intake pipe can be inserted into the outer cylinder, and the second air intake pipe can be attached to the outer cylinder; and both the first exhaust pipe and the second exhaust pipe can be inserted into the inner cylinder, The connection portion is characterized in that the first intake and exhaust pipes can be connected by inserting the first intake and exhaust pipes into the outer cylinder and the first exhaust pipes into the inner cylinder, and the second intake and exhaust pipes can be connected by fitting the second intake and exhaust pipes to the outside of the outer cylinder and inserting the second exhaust pipes into the inner cylinder. In another aspect of the present disclosure, in the above configuration, an outer diameter of a lower portion of the second exhaust pipe is smaller than an outer diameter of a lower portion of the first exhaust pipe, The external cylinder is provided with a first air intake pipe restricting portion on its inner surface that restricts the insertion position of the first air intake pipe and a second air intake pipe restricting portion on its outer surface that restricts the external fitting position of the second air intake pipe, the first air intake pipe restricting portion being spaced apart from the first air intake pipe, the inner cylinder is provided with a first exhaust pipe restriction portion that restricts the insertion position of the first exhaust pipe, and a second exhaust pipe restriction portion that restricts the insertion position of the second exhaust pipe at a position lower than the first exhaust pipe restriction portion, A first seal member that abuts against the outer surface of the inserted first exhaust pipe, and a second seal member that abuts against the outer surface of the inserted second exhaust pipe are provided on the inner surface of the inner cylinder, spaced apart from each other above and below. When the first intake and exhaust pipe is connected to the connecting portion, the first intake pipe inserted into the outer cylinder is restricted from insertion by the first intake pipe restricting portion, and the first exhaust pipe inserted into the inner cylinder is restricted from insertion by the first exhaust pipe restricting portion, and the first seal member abuts against the outer peripheral surface of the first exhaust pipe, When the second intake and exhaust pipe is connected to the connection portion, the second intake pipe fitted onto the outer cylinder is restricted from fitting externally by the second intake pipe regulating portion, the second exhaust pipe inserted into the inner cylinder is restricted from being inserted internally by the second exhaust pipe regulating portion, and the second sealing member abuts against the outer peripheral surface of the second exhaust pipe. Another aspect of the present disclosure is characterized in that, in the above configuration, the first exhaust pipe regulating portion is a tapered portion that tapers downward, has a diameter smaller than the outer diameter of the lower end of the first exhaust pipe, and is larger than the outer diameter of the second exhaust pipe. Another aspect of the present disclosure is characterized in that, in the above configuration, a connecting member is installed between the inner surface of the outer tube and the outer surface of the inner tube to coaxially connect the two tubes, and the upper end of the connecting portion of the connecting member that connects with the inner surface of the outer tube also serves as the first air intake pipe regulating portion. [Effects of the Invention]

[0007] According to the present disclosure, the first intake and exhaust pipe can be connected to the connecting part by inserting the first intake pipe into the outer cylinder and the first exhaust pipe into the inner cylinder, and the second intake and exhaust pipe can be connected to the connecting part by fitting the second intake pipe onto the outer cylinder and inserting the second exhaust pipe into the inner cylinder. Thus, both first and second intake and exhaust pipes of two types with different diameters can be connected to the connecting part. According to another aspect of the present disclosure, in addition to the above-mentioned effects, by providing restricting portions on the outer and inner cylinders, the first and second intake and exhaust pipes can be connected to the connecting portions at appropriate positions. Also, the gap between the inner cylinder and the first and second exhaust pipes can be reliably sealed, preventing leakage of combustion exhaust gas. According to another aspect of the present disclosure, in addition to the above effects, the first exhaust pipe restriction portion is a tapered portion that is smaller in diameter than the outer diameter of the lower end of the first exhaust pipe and larger in diameter than the outer diameter of the second exhaust pipe, thereby enabling proper positioning of the first exhaust pipe while allowing the passage of the second exhaust pipe, which is longer below the first exhaust pipe. According to another aspect of the present disclosure, in addition to the above effects, the connection portion of the connecting member with the inner surface of the outer tube also serves as the first air intake pipe regulating portion, so that the connecting member can be used to regulate the insertion of the first air intake pipe, resulting in a rational configuration with a reduced number of parts. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a front view of the water heater with the front cover removed. [Figure 2] FIG. 2 is a rear perspective view of the exhaust hood. [Figure 3] FIG. 2 is a plan view of the exhaust hood. [Figure 4] 3A shows a partial cross section taken along line AA in FIG. 3, (B) shows a partial cross section taken along line BB in FIG. 3, and (C) shows a partial cross section taken along line CC in FIG. [Figure 5] FIG. 10 is a front perspective view of the exhaust hood and the connection portion. [Figure 6] FIG. 10 is a side view of the exhaust hood and connection portion. [Figure 7] FIG. [Figure 8] FIG. 8 is a partial cross-sectional view taken along the line DD in FIG. 7. [Figure 9] 8 is a partial cross-sectional view corresponding to the cross section of line DD in FIG. 7, showing a state in which the first air supply / exhaust pipe is connected. [Figure 10] 8 is a partial cross-sectional view corresponding to the cross section of line DD in FIG. 7, showing a state in which a second intake / exhaust pipe is connected. [Figure 11] FIG. 10 is a cross-sectional view taken along the line EE in FIG. 9. [Figure 12] FIG. 11 is a cross-sectional view taken along the line FF in FIG. 10. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. FIG. 1 is a front view showing an example of a water heater with the front cover removed. The water heater 1 has a housing 2 that is rectangular when viewed from the front. The housing 2 is made up of a box body 3 that is open at the front and deep at the front and rear, and a front cover (not shown) that closes the front of the box body 3 and is shallower than the box body 3. The box body 3 has a back panel 4, left and right side panels 5, 5, a top panel 6, and a bottom panel 7. A mounting plate 8 is attached to the front of the back panel 4. Brackets 9, 9 are attached to the top and bottom of the rear surface of the back panel 4 for mounting to a vertical surface such as a wall. A combustion device 10 is installed inside the box body 3, and includes, from below, a burner unit 11, a heat exchanger 12, and an exhaust hood 13. A connection part 14 for connecting to an intake and exhaust pipe (described later) is provided above the exhaust hood 13. A fan 15 having a fan motor is provided below the burner unit 11. A controller (not shown) is provided in front of the fan 15.

[0010] The burner unit 11 accommodates a plurality of burners (not shown) in a lower casing 16. A nozzle base 17 for supplying fuel gas to the burners is provided on the front surface of the lower casing 16. The heat exchanger 12 has an upper casing 18 connected to the upper side of the lower casing 16. A serpentine heat transfer pipe 19 is provided inside the upper casing 18. The upstream end of the heat transfer pipe 19 is connected to a water supply pipe 20, and the downstream end is connected to a hot water outlet pipe 21. The water supply pipe 20 and the hot water outlet pipe 21 are connected to external piping below the bottom plate 7.

[0011] The exhaust hood 13 is attached to the upper end of the upper casing 18. As shown in Figures 2 and 3, the exhaust hood 13 includes a box-shaped main body 25 that is open at the bottom, and a flange 26 that is rectangular and elongated in plan view and that is formed by extending outward and inward directions from the bottom end of the main body 25. The outer periphery of the flange 26 is attached to the upper casing 18. The main body 25 is formed by drawing a metal plate upward and has a horizontally elongated rectangular shape in a plan view, and includes a top surface 27, a front surface 28, a rear surface 29, and left and right side surfaces 30, 30. The boundaries between the top surface 27 and each of the front, rear, left and right surfaces are rounded portions 31, 31... that curve downward as they move away from the top surface 27 in the front, rear, left and right directions. A support bar 22 (FIGS. 1 and 5) extending in the left-right direction is attached to the rear surface portion 29. The support bar 22 is fixed to the mounting plate 8 on the back panel 4 side.

[0012] The top surface 27 is provided with a through-hole 32 that is circular in plan view. The through-hole 32 is provided in the left-right center of the top surface 27, and toward the rear. A short, cylindrical burring portion 33 that rises upward is formed on the inner edge of the through-hole 32. The through-hole 32 and the burring portion 33 are located toward the rear because the folded-back portions of the serpentine heat transfer tubes 19 also protrude rearward from the upper casing 18 of the heat exchanger 12, and therefore the combustion device 10 is positioned toward the front within the housing 2, making it possible to connect the connection portion 14 to an existing intake and exhaust pipe whose position is fixed externally.

[0013] The rear end of the burring portion 33 is close to the rear surface portion 29. For this reason, in the rear R portion 31 (hereinafter referred to as "31A" when distinguishing between them) formed between the top surface portion 27 and the rear surface portion 29, the curvature R1 is greatest on both the left and right sides away from the through hole 32 as shown in Fig. 4(A), and as it approaches the through hole 32, the curvature R2 gradually decreases as shown in Fig. 4(B), and is formed so that the curvature R1 is smallest at the position directly behind the center of the through hole 32 as shown in Fig. 4(C). As a result, even if the through-hole 32 is provided toward the rear of the top surface portion 27, the through-hole 32 and the burring portion 33 do not overlap with the rear R portion 31A. Therefore, the burring portion 33 can be easily formed on the flat top surface portion 27.

[0014] 5 is a perspective view of the exhaust hood 13 and the connection portion 14 from the front, FIG. 6 is a side view, FIG. 7 is a plan view of the connection portion, and FIG. 8 is a cross-sectional view taken along line DD in FIG. A cylindrical lower exhaust tube 34 is connected to the burring portion 33. The lower exhaust tube 34 is a cylinder that is fitted onto the outside of the burring portion 33 and extends upward. The connecting portion 14 includes an outer cylinder 40, an inner cylinder 41, and a connecting plate 42. The outer cylinder 40 extends upward through a through-hole (not shown) provided in the top plate 6 of the box body 3. A flange plate 43 that projects radially outward is attached to the entire circumference of the lower end of the outer cylinder 40. A receiving plate 44 (FIGS. 1 and 8) to which the flange plate 43 is fixed is provided on the mounting plate 8 above the exhaust hood 13. A through-hole 45 that opens the lower end opening of the outer cylinder 40 into the housing 2 is formed in the bottom surface of the receiving plate 44. The upper part of the outer cylinder 40 is formed with a large outer diameter portion 46 that widens upward and then extends upward to a larger diameter than the lower part. Above the large outer diameter portion 46 is formed a small outer diameter portion 47 with a smaller outer diameter, forming a stepped outer restricting portion 48 around the entire circumference between the large outer diameter portion 46 and the small outer diameter portion 47. At the upper end of the outer cylinder 40, an inward folded portion 49 is formed around the entire circumference.

[0015] The inner tube 41 is a cylinder that extends upward within the outer tube 40, with its lower end fitted onto the lower exhaust tube 34. A ring-shaped lower retaining portion 50 is formed at the lower end of the inner tube 41. The ring-shaped lower retaining portion 50 retains an O-ring 51 that abuts against the outer peripheral surface of the lower exhaust tube 34. A constricted portion 52 is formed above the lower retaining portion 50. An upper exhaust tube 53 is provided inside the constricted portion 52. The upper exhaust tube 53 is a cylinder that is positioned coaxially above the lower exhaust tube 34 and is fixed such that its lower outer peripheral surface abuts against the inner peripheral surface of the constricted portion 52 around its entire circumference. The upper portion of the upper exhaust tube 53 is formed with a tapered portion 54 that tapers upward, and a small-diameter tip portion 55 is formed above the tapered portion 54. Above the constricted portion 52, the inner tube 41 extends upward outside the tip portion 55, forming a ring-shaped space S between the tip portion 55 and the constricted portion 52. An end of a sensor tube 56 that penetrates the outer tube 40 and the inner tube 41 from the radially outer side protrudes into this space S. The sensor tube 56 is used to house a temperature sensor (not shown) and detect the temperature of the combustion exhaust gas in the space S.

[0016] A tapered lower restricting portion 60 that widens upward is formed on the inner tube 41 outside the tip portion 55. A band-shaped middle holding portion 61 that bulges outward is formed above the lower restricting portion 60. A band-ring-shaped sealing plate 62 is held inside the middle holding portion 61. An upper restricting portion 63 having a tapered shape that widens as it extends upward is formed on the upper side of the sealing plate 62. An upper holding portion 64 having a ring shape that holds an O-ring 65 is formed on the upper side of the upper restricting portion 63. The connecting plates 42 are plate-shaped and arranged radially between the inner peripheral surface of the outer tube 40 and the outer peripheral surface of the inner tube 41. Three connecting plates 42 are arranged at equal intervals around the circumference of both tubes 40, 41 to coaxially connect the outer tube 40 and the inner tube 41. Each connecting plate 42 consists of a lower plate portion 66 connected to the inner peripheral surface of the outer tube 40, an upper plate portion 67 connected to the outer peripheral surface of the inner tube 41, and an inclined plate portion 68 connecting the lower plate portion 66 and the upper plate portion 67. The lower plate portion 66 is fixed above the outer restricting portion 48 of the outer tube 40, and the upper plate portion 67 is fixed above the upper retaining portion 64 of the inner tube 41.

[0017] In the water heater 1 configured as described above, two types of first supply and exhaust pipes 70 and second supply and exhaust pipes 80 can be selectively connected to the connection portion 14, as shown in Figures 9 and 10. First, the first air intake / exhaust pipe 70 comprises a first air intake pipe 71 and a first exhaust pipe 72, which are coaxial. The first air intake pipe 71 is a cylinder having an outer diameter that allows it to be inserted from above into the outer cylinder 40 of the connecting part 14. The lower end of the first air intake pipe 71 can abut against the upper end of the lower plate part 66 of the connecting plate 42 when inserted into the outer cylinder 40. The first exhaust pipe 72 is a cylinder having an outer diameter that allows it to be inserted from above into the inner cylinder 41. The lower end of the first exhaust pipe 72 protrudes downward beyond the lower end of the first air intake pipe 71, and forms a first tapered section 73 that reduces in diameter as it extends downward. This first tapered section 73 can come into contact with the upper restricting section 63 provided on the inner cylinder 41 as it is inserted into the inner cylinder 41.

[0018] Therefore, when connecting the first air intake and exhaust pipe 70 to the connecting portion 14, the first air intake pipe 71 is inserted from above into the outer cylinder 40, and the first exhaust pipe 72 is inserted from above into the inner cylinder 41. Then, as shown in Figures 9 and 11, the lower end of the first air intake pipe 71 abuts against the upper end of the lower plate portion 66 of each connecting plate 42, and the first tapered portion 73 of the first exhaust pipe 72 abuts against the upper restricting portion 63 of the inner cylinder 41, restricting further insertion. At this time, the O-ring 65 of the inner cylinder 41 abuts against the outer peripheral surface of the first exhaust pipe 72 over the entire circumference, sealing the gap between the inner cylinder 41 and the first exhaust pipe 72.

[0019] Next, the second intake / exhaust pipe 80 comprises a second intake pipe 81 and a second exhaust pipe 82, which are coaxially arranged. The second intake pipe 81 is a cylinder with an inner diameter that allows it to be fitted from above onto the outer tube 40 of the connecting part 14. A tapered second lower abutment portion 83 that widens downward is provided at the lower part of the second intake pipe 81. The second lower abutment portion 83 is capable of abutting against the outer restricting portion 48 provided on the outer tube 40 as it is fitted onto the outer tube 40. A tapered second upper abutment portion 84 that widens downward is also provided above the second lower abutment portion 83. The second upper abutment portion 84 is capable of abutting against the folded-back portion 49 at the upper end of the outer tube 40 at the same time that the second lower abutment portion 83 abuts against the outer restricting portion 48. The second exhaust pipe 82 is a cylinder having an outer diameter that allows it to be inserted from above into the inner cylinder 41. The lower part of the second exhaust pipe 82 has an outer diameter that is smaller than the outer diameter of the first exhaust pipe 72 of the first intake and exhaust pipe 70 and the inner diameter of the upper restricting portion 63 of the inner cylinder 41, and the lower end protrudes downward beyond the lower end of the second intake pipe 81. The lower end of the second exhaust pipe 82 is provided with a second tapered section 85 that reduces in diameter as it extends downward.

[0020] Therefore, when connecting the second intake / exhaust pipe 80 to the connecting portion 14, the second intake pipe 81 is fitted onto the outer cylinder 40 from above, and the second exhaust pipe 82 is inserted into the inner cylinder 41 from above. Then, as shown in FIGS. 10 and 12 , the second lower abutment portion 83 of the second exhaust pipe 81 comes into contact with the outer restricting portion 48 of the outer cylinder 40, and the second upper abutment portion 84 comes into contact with the folded-back portion 49, restricting further fitting. At this time, the second exhaust pipe 82 passes through the O-ring 65 and the seal plate 62, and the second tapered portion 85 at its lower end comes into close proximity to or abuts the lower restricting portion 60. In this inserted state, the lip on the inner peripheral surface of the seal plate 62 abuts against the outer peripheral surface of the second exhaust pipe 82 over the entire circumference, sealing the gap between the inner cylinder 41 and the second exhaust pipe 82.

[0021] (Effect of disclosure regarding connections to intake and exhaust pipes) In the water heater 1 of the above form, a first air supply / exhaust pipe 70 having a first air supply / exhaust pipe 71 corresponding to the outer tube 40 and a first exhaust pipe 72 corresponding to the inner tube 41, which are coaxially connected to the connection part 14, and a second air supply / exhaust pipe 80 having a second air supply / exhaust pipe 81 corresponding to the outer tube 40 and having an inner diameter larger than the outer diameter of the first air supply pipe 71 and a second exhaust pipe 82 corresponding to the inner tube 41, which are coaxially connected to the connection part 14. The first air intake and exhaust pipe 70 can be connected to the connection portion 14 by inserting the first air intake pipe 71 into the outer tube 40 and the first exhaust pipe 72 into the inner tube 41, and the second air intake and exhaust pipe 80 can be connected by fitting the second air intake pipe 81 to the outside of the outer tube 40 and inserting the second exhaust pipe 82 into the inner tube 41. According to this configuration, both of the first and second intake and exhaust pipes 70, 80 of two types with different diameters can be connected to the connection portion .

[0022] The outer diameter of the lower part of the second exhaust pipe 82 is smaller than the outer diameter of the lower part of the first exhaust pipe 72, and the outer tube 40 has a lower plate part 66 (an example of a first air intake pipe regulating part) of the connecting plate 42 on the inner surface which regulates the insertion position of the first air intake pipe 71, and an outer regulating part 48 (an example of a second air intake pipe regulating part) on the outer surface which regulates the external fitting position of the second air intake pipe 81, each spaced apart from the others. On the other hand, the inner tube 41 is provided with an upper regulating portion 63 (an example of a first exhaust pipe regulating portion) that regulates the insertion position of the first exhaust pipe 72, and a lower regulating portion 60 (an example of a second exhaust pipe regulating portion) that regulates the insertion position of the second exhaust pipe 82 at a position lower than the upper regulating portion 63. Additionally, an O-ring 65 (an example of a first sealing member) that abuts against the outer surface of the inserted first exhaust pipe 72 and a sealing plate 62 (an example of a second sealing member) that abuts against the outer surface of the inserted second exhaust pipe 82 are provided on the inner surface of the inner tube 41, spaced apart from each other above and below. When the first intake and exhaust pipe 70 is connected to the connection portion 14, the first intake pipe 71 inserted into the outer tube 40 is restricted from being inserted by the lower plate portion 66, and the first exhaust pipe 72 inserted into the inner tube 41 is restricted from being inserted by the upper restricting portion 63, and the O-ring 65 abuts against the outer surface of the first exhaust pipe 72. On the other hand, when the second intake and exhaust pipe 80 is connected to the connection portion 14, the second intake pipe 81 fitted onto the outer tube 40 is restricted from fitting externally by the outer regulating portion 48, and the second exhaust pipe 82 inserted into the inner tube 41 is restricted from being inserted internally by the lower regulating portion 60, and the sealing plate 62 abuts against the outer peripheral surface of the second exhaust pipe 82. This configuration allows the first and second supply and exhaust pipes 70, 80 to be connected at appropriate positions to the connecting portion 14. Also, the gap between the inner cylinder 41 and the first and second exhaust pipes 72, 82 can be reliably sealed, making it possible to prevent leakage of combustion exhaust gas.

[0023] The upper restricting portion 63 is a tapered portion that tapers downward to a diameter smaller than the outer diameter of the lower end of the first exhaust pipe 72 and larger than the outer diameter of the second exhaust pipe 82 . Therefore, it is possible to properly position the first exhaust pipe 72 while allowing the second exhaust pipe 82, which is longer than the first exhaust pipe 72, to pass downward. A connecting plate 42 (an example of a connecting member) that coaxially connects the two tubes 40, 41 is installed between the inner surface of the outer tube 40 and the outer surface of the inner tube 41, and the upper end of the lower plate portion 66, which is the connection part of the connecting plate 42 with the inner surface of the outer tube 40, also serves as the first air intake pipe regulating part. Therefore, the connecting plate 42 can be used to restrict the insertion of the first air supply pipe 71, resulting in a rational configuration with a reduced number of parts.

[0024] Below, a modified example relating to the disclosure of the connection portion of the intake and exhaust pipes will be described. In the above embodiment, the first and second exhaust pipes of the first and second intake and exhaust pipes have different downward protrusion lengths relative to the connection portion, with the second exhaust pipe being longer than the first exhaust pipe, but the opposite may be true, or both exhaust pipes may be the same length. In this case, the first exhaust pipe restriction portion can serve as both the first and second exhaust pipe restriction portion (in the above embodiment, either the O-ring or the sealing plate can be used). In the above embodiment, the first air intake pipe restricting portion also serves as the connecting plate, but the first air intake pipe restricting portion may be formed separately from the connecting plate. The connecting members are not limited to the connecting plates of the above-described embodiment. The number and shape of the connecting members may be changed as appropriate. For example, rod-shaped connecting members may be provided between the outer cylinder and the inner cylinder in the radial direction. In the above embodiment, the second intake pipe regulating portion and the first and second exhaust pipe regulating portions are tapered regulating portions, but this is not limited to this and the regulating portions may be formed using ribs or protrusions that protrude radially. In the above embodiment, when the first intake and exhaust pipes are connected, the first intake pipe abuts against the first intake pipe restricting portion, and the first exhaust pipe abuts against the first exhaust pipe restricting portion, but it is also possible for only one of the first intake pipe and the first exhaust pipe to abut against the corresponding restricting portion, with the other pipe approaching the corresponding restricting portion and restricted from moving. In the above embodiment, the lower exhaust stack of the exhaust hood does not have to be disposed rearward.

[0025] (Effect of disclosure regarding exhaust hoods) The water heater 1 of the above embodiment comprises a housing 2 whose rear surface is a surface to be installed on a vertical surface, and a combustion device 10 provided within the housing 2, including a burner unit 11 (an example of a burner), a heat exchanger 12 above the burner unit 11, and an exhaust hood 13 provided above the burner unit 11 and having a lower exhaust pipe 34 (an example of an exhaust pipe) connected to its upper surface. The exhaust hood 13 has a top surface 27 that is a rectangular flat surface in a plan view, and its four sides are drawn to bulge upward and connect to the front, rear, left, and right surfaces via rounded portions 31, and a burring portion 33 to which the lower exhaust pipe 34 is connected is formed on the periphery of a through hole 32 formed in the top surface 27. The through hole 32 is positioned rearward from the center of the top surface 27 in the front-to-rear direction, and the R portion 31A on the rear side of the top surface 27 is formed so that the curvatures R3 to R1 gradually decrease as one approaches the through hole 32 from the outside in the left-to-right direction. According to this configuration, the position of the burring portion 33 does not straddle the flat top surface portion 27 of the exhaust hood 13 and the R portion 31A on the rear side thereof. Therefore, even when an exhaust hood 13 is used in which the burring portion 33 is located toward the rear, the burring portion 33 can be formed without distortion, and the dimensional accuracy of the burring portion 33 can be maintained.

[0026] Modifications relating to the disclosure of the exhaust hood will be described below. The main body of the exhaust hood does not have to be rectangular in shape extending in the left-right direction in plan view as in the above embodiment, but may be rectangular in shape extending in the front-rear direction in plan view or may be square in plan view. In the above embodiment, the burring portion is located in the center of the top surface in the left-right direction, but it may be located to either the left or right. In this case, the rear R portion should also be formed so that the curvature decreases as it approaches the burring portion. The rearward position of the burring portion is not limited to the above-described form, and it may be closer to the center than the above-described form.

[0027] Additionally, as common to all disclosures, the water heater may be a latent heat recovery type having a primary heat exchanger and a secondary heat exchanger. The heat exchanger may be divided into two circuits: a hot water supply circuit and another circuit (for example, a bath circuit or a heating circuit). [Explanation of symbols]

[0028] 1·· Water heater, 2·· Housing, 3·· Box body, 10·· Combustion device, 11·· Burner unit, 12·· Heat exchanger, 13·· Exhaust hood, 14·· Connection part, 15·· Fan, 25·· Main body part, 26·· Flange part, 27·· Top surface part, 29·· Rear surface part, 31 (31A)·· R part, 32·· Through hole, 33·· Burring part, 34·· Lower exhaust pipe, 40·· Outer pipe, 41·· Inner pipe, 42·· Connecting plate, 48·· Outer regulation part , 51,65··O-ring, 53··upper exhaust pipe, 60··lower restriction portion, 62··seal plate, 63··upper restriction portion, 66··lower plate portion, 67··upper plate portion, 68··inclined plate portion, 70··first intake and exhaust pipe, 71··first air intake pipe, 72··first exhaust pipe, 73··first tapered portion, 80··second intake and exhaust pipe, 81··second air intake pipe, 82··second exhaust pipe, 83··second lower abutment portion, 84··second upper abutment portion, 85··second tapered portion.

Claims

1. a housing for accommodating a combustion device equipped with a fan; The connection part of the water heater includes an outer cylinder for drawing air into the housing as the fan is driven, and an inner cylinder arranged coaxially within the outer cylinder and for discharging the combustion exhaust gas that has passed through the combustion device, and the connection part is formed by projecting the outer cylinder upward from the top surface of the housing, a first intake and exhaust pipe including a first intake pipe corresponding to the outer cylinder and a first exhaust pipe corresponding to the inner cylinder, the first intake and exhaust pipe being coaxial with each other; A connection structure between a water heater and an air supply and exhaust pipe, which can selectively connect a second air supply and exhaust pipe that is coaxially provided with a second air supply pipe that corresponds to the outer cylinder and has an inner diameter larger than an outer diameter of the first air supply pipe, and a second exhaust pipe that corresponds to the inner cylinder, the first air intake pipe can be inserted into the outer cylinder, and the second air intake pipe can be attached to the outer cylinder; and both the first exhaust pipe and the second exhaust pipe can be inserted into the inner cylinder, A connection structure between a water heater and an air supply and exhaust pipe, characterized in that the first air supply and exhaust pipe can be connected to the connection portion by inserting the first air supply pipe into the outer cylinder and the first exhaust pipe into the inner cylinder, and the second air supply and exhaust pipe can be connected to the connection portion by fitting the second air supply pipe to the outside of the outer cylinder and inserting the second exhaust pipe into the inner cylinder.

2. an outer diameter of a lower portion of the second exhaust pipe is smaller than an outer diameter of a lower portion of the first exhaust pipe, The external cylinder is provided with a first air intake pipe restricting portion on its inner surface that restricts the insertion position of the first air intake pipe and a second air intake pipe restricting portion on its outer surface that restricts the external fitting position of the second air intake pipe, the first air intake pipe restricting portion and the second air intake pipe restricting portion being spaced apart from each other above and below; the inner cylinder is provided with a first exhaust pipe restriction portion that restricts the insertion position of the first exhaust pipe, and a second exhaust pipe restriction portion that restricts the insertion position of the second exhaust pipe at a position lower than the first exhaust pipe restriction portion, a first seal member that contacts the outer peripheral surface of the inserted first exhaust pipe and a second seal member that contacts the outer peripheral surface of the inserted second exhaust pipe are provided on an inner peripheral surface of the inner cylinder, the first seal member being spaced apart from the second seal member; When the first intake and exhaust pipe is connected to the connection portion, the first intake pipe inserted into the outer cylinder is restricted from insertion by the first intake pipe restricting portion, the first exhaust pipe inserted into the inner cylinder is restricted from insertion by the first exhaust pipe restricting portion, and the first seal member abuts against the outer peripheral surface of the first exhaust pipe, The connection structure between a water heater and an air supply and exhaust pipe as described in claim 1, characterized in that when the second air supply and exhaust pipe is connected to the connection portion, the second air supply pipe fitted onto the outer tube is restricted from fitting externally by the second air supply pipe regulating portion, the second exhaust pipe inserted into the inner tube is restricted from being inserted internally by the second exhaust pipe regulating portion, and the second sealing member abuts against the outer surface of the second exhaust pipe.

3. The connection structure between a water heater and a supply and exhaust pipe as described in claim 2, characterized in that the first exhaust pipe regulating portion is a tapered portion that tapers downward, having a diameter smaller than the outer diameter of the lower end of the first exhaust pipe and a diameter larger than the outer diameter of the second exhaust pipe.

4. A connecting member that connects the two tubes coaxially is installed between the inner surface of the outer tube and the outer surface of the inner tube, and the upper end of the connecting portion of the connecting member that connects with the inner surface of the outer tube is also used as the first air supply pipe regulating portion.

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