Heat exchanger and water heater

Abstract

To provide a heat exchanger and a water heater capable of efficiently recovering heat, in the heat exchanger provided with meander-shaped heat transfer tubes arranged inside.SOLUTION: A heat exchanger includes: a casing into which combustion exhaust is supplied; and a plurality of heat transfer tubes housed inside of the casing. The casing includes: a side wall portion disposed at one end portion in a second direction orthogonal to a first direction in which the combustion exhaust is supplied; and an opposed wall portion opposed to the side wall portion in the second direction. The plurality of heat transfer tubes are formed into a meander shape as a whole, and have: a plurality of straight tube portions 62A arranged in the first direction with an attitude facing the second direction; and a plurality of folding tube portions 62B connecting one end portions and the other end portions in the second direction of the plurality of straight tube portions 62A. Both end portions of the heat transfer tubes are inserted and fixed to the side wall portion at intervals in the first direction, and the opposed wall portion of the casing is provided with a deflection guide 69 for deflecting the combustion exhaust flowing along the opposed wall portion to a side wall portion side.SELECTED DRAWING: Figure 12

Description

Technical Field

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

Background Art

[0002] As a heat exchanger used in a water heater, for example, a secondary heat exchanger described in Japanese Patent Application Laid-Open No. 2020-186884 (hereinafter referred to as Patent Document 1) is known. The secondary heat exchanger has a case and a heat transfer tube portion. The case includes a peripheral wall portion that surrounds a passage space for exhaust gas, a bottom wall portion provided on the lower end side of the peripheral wall portion, and a lid portion that closes an opening provided at an upper end portion of the peripheral wall portion. The peripheral wall portion includes a front wall portion provided with an exhaust gas outlet, a rear wall portion provided with an exhaust gas inlet, and a pair of side wall portions that connect both end portions of the front wall portion and both end portions of the rear wall portion and face each other in the left-right direction. The heat transfer tube portion includes a plurality of heat transfer tubes housed in the case.

[0003] The heat transfer tubes are formed in a meandering shape as a whole, and include a plurality of linear tube portions arranged in parallel in the front-rear direction in a posture facing the left-right direction, and a plurality of folding portions that connect one end portion and the other end portion in the left-right direction of the linear tube portions. Both end portions of the heat transfer tubes are directed toward one side in the left-right direction, and are inserted and fixed at intervals in the front-rear direction with respect to the side wall portion located on the one side among the pair of side wall portions of the housing.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in this type of secondary heat exchanger, considering the dimensional tolerances and assembly tolerances of each component, a clearance is designed to be ensured to a certain extent between the folded-back portion located on the other side in the left-right direction and the opposing wall portion (the side wall portion or partition located on the other side among the pair of side wall portions) facing this folded-back portion. In addition to this, since the folded-back portion is formed by bending with a predetermined curvature, there are more gaps in the arrangement region of the folded-back portion than in the arrangement region of the straight tube portion, and the exhaust resistance is reduced accordingly. Then, a part of the exhaust gas introduced into the case from the inlet and heading toward the outlet is deflected toward the folded-back portion side located on the other side, flows along the opposing wall portion, and is discharged to the outside without being sufficiently heat-exchanged.

[0006] An object of the present invention is to provide a heat exchanger and a water heater capable of efficiently recovering heat in a heat exchanger in which a serpentine heat transfer tube is disposed inside.

Means for Solving the Problems

[0007] The heat exchanger of the present disclosure is a heat exchanger including a casing into which combustion exhaust is supplied and a plurality of heat transfer tubes housed inside the casing, wherein the casing includes a side wall portion disposed at one end in a second direction orthogonal to a first direction into which the combustion exhaust is supplied, and an opposing wall portion opposing the side wall portion in the second direction, the plurality of heat transfer tubes are formed in a serpentine shape as a whole, and include a plurality of straight tube portions arranged in parallel in the first direction in a posture facing the second direction, and a plurality of folded-back tube portions connecting one ends and the other ends in the second direction of the plurality of straight tube portions, both ends of the heat transfer tube are inserted and fixed at intervals in the first direction with respect to the side wall portion, and a flow deflection guide for deflecting the combustion exhaust flowing along the opposing wall portion toward the side wall portion side is provided on the opposing wall portion of the casing.

Effects of the Invention

[0008] According to the present invention, efficient heat recovery can be performed.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present disclosure will be listed and exemplified. (1) The heat exchanger of the present disclosure is a heat exchanger including a casing into which combustion exhaust gas is supplied, and a plurality of heat transfer tubes housed inside the casing. The casing includes a side wall portion disposed at one end in a second direction orthogonal to a first direction in which the combustion exhaust gas is supplied, and an opposing wall portion opposing the side wall portion in the second direction. The plurality of heat transfer tubes are formed in a meandering shape as a whole, and include a plurality of straight tube portions arranged in parallel in the first direction in a posture facing the second direction, and a plurality of return tube portions connecting one ends and the other ends in the second direction of the plurality of straight tube portions. Both ends of the heat transfer tube are inserted and fixed with a space in the first direction with respect to the side wall portion. A flow deflection guide for deflecting the combustion exhaust gas flowing along the opposing wall portion toward the side wall portion is provided on the opposing wall portion of the casing. Since the flow deflection guide can deflect the combustion exhaust gas flowing along the opposing wall portion toward the side wall portion, it is possible to suppress the combustion exhaust gas from being discharged without being heat-exchanged.

[0011] (2) The flow deflection guide has a protruding plate protruding toward the side wall portion. With a simple configuration of the protruding plate, the combustion exhaust gas can be guided.

[0012] (3) The protruding plate of the flow deflection guide is provided on the upstream side of the return tube portion located on the opposing wall portion side. There are more gaps around the return tube portion than around the straight tube portion. In contrast, since the protruding plate is arranged on the upstream side of each return tube portion, it is possible to effectively suppress the combustion exhaust gas from flowing into the opposing wall portion side through the gaps around the return tube portion.

[0013] (4) The return pipe portions on the side of the opposing wall portion are provided with at least three strips, and the flow deviation guide is formed in a U-shape in plan view, comprising a pair of the protruding plates arranged at intervals in the first direction, and a fixing plate connecting the pair of protruding plates and fixed to the opposing wall portion. The flow deviation guide is arranged such that the pair of protruding plates do not face the return pipe portions on the side of the opposing wall portion that are the odd-numbered ones when viewed from the upstream side in the first direction among the three return pipe portions, and surrounds the return pipe portions from both sides in the first direction. With the flow deviation guide of the same shape, the protruding plates can be arranged on the upstream side of all the return pipe portions located on the side of the opposing wall portion, so that an increase in the number of parts can be prevented, and incorrect assembly can be prevented.

[0014] (5) An exhaust pipe for discharging the combustion exhaust inside the casing upward is provided on the ceiling wall portion of the casing, and a partition plate for vertically partitioning the region where the heat transfer pipes are arranged and the lower region of the ceiling wall portion is provided inside the casing. A communication portion for shortcutting the combustion exhaust flowing through the region where the heat transfer pipes are arranged to the lower region of the ceiling wall portion is provided at a position excluding at least the end portion on the side of the opposing wall portion in the partition plate. By providing the communication portion, the combustion exhaust can flow more easily to the side wall portion side, so that the combustion exhaust flowing through the side of the opposing wall portion can be guided to the side wall portion side more favorably by the synergistic effect with the flow deviation guide.

[0015] (6) The side wall portions are arranged in a pair at both ends of the casing in the second direction. The casing has a partition wall that separates and partitions the internal space of the casing in the second direction, and the opposing wall portion is the partition wall. For example, by separating and partitioning the internal space of the casing by the partition wall, the hot water supply heat exchanger and the bath heat exchanger may be configured as one heat exchanger. Also in such a heat exchanger, the flow deviation guide can cause the combustion exhaust flowing along the partition wall to deviate to the side wall portion side.

[0016] (7) The water heater of the present disclosure includes a combustion device, a primary heat exchanger provided continuously with the combustion device through which combustion exhaust from the combustion device passes, and a secondary heat exchanger which is a heat exchanger provided continuously with the primary heat exchanger through which combustion exhaust from the primary heat exchanger passes. In a heat exchanger having a serpentine heat transfer tube disposed therein, it is possible to provide a heat exchanger and a water heater capable of performing efficient heat recovery.

[0017] <Embodiment 1> Hereinafter, Embodiment 1 of the present disclosure will be described with reference to FIGS. 1 to 13. In the following description, the front-rear direction, the up-down direction, and the left-right direction are based on the directions indicated by the four-direction arrows in each figure.

[0018] [Overall Structure of the Water Heater] FIG. 1 is a front view of the water heater 1 as seen from the front, showing a state in which the front front cover is removed. The water heater 1 has a configuration in which a combustion device 4, a primary heat exchanger 5, and a secondary heat exchanger (an example of a heat exchanger) 6 are sequentially provided from below in an inner cylinder 3 housed in a rectangular box-shaped housing 2 having an open front surface. A gas supply unit 7 for distributing and supplying fuel gas to the burner unit in the combustion device 4 is assembled on the front surface of the combustion device 4. An intake fan 8 for supplying combustion air is assembled on the lower surface of the combustion device 4. A controller 9 housing an electrical component board is installed on the lower right side of the inner cylinder 3. A path member 10 is disposed between the primary heat exchanger 5 and the secondary heat exchanger 6.

[0019] The water heater 1 includes a drain hose 14. The upstream end of the drain hose 14 is connected to the drain outlet 68 of the secondary heat exchanger 6, and the downstream end is connected to a neutralizer. Drain generated by latent heat recovery in the secondary heat exchanger 6 is discharged to the outside of the secondary heat exchanger 6 through the drain outlet 68 and sent to the neutralizer through the drain hose 14.

[0020] The water heater 1 includes a controller 9 as a control device. The controller 9 is configured as, for example, a known microcomputer or the like, and is configured to be able to acquire signals from various sensors provided in the water heater 1, and to be able to control various actuators provided in the water heater 1. For example, when the water flow sensor detects water flow in the water inlet pipe 11, the water heater 1 operates the combustion device 4 to generate hot water.

[0021] [Combustion device] The combustion device 4 is connected to the lower part of the primary heat exchanger 5. The combustion device 4 has an inner case 41 in the shape of a square box that fits inside the housing 2. The combustion device 4 mixes the combustion gas and air supplied to each burner unit inside the burner unit, and ejects and burns this mixed gas upward from the flame holes formed at the downstream end to generate combustion exhaust gas.

[0022] [Path member] The path member 10 is a member that connects the primary heat exchanger 5 and the secondary heat exchanger 6. The lower end of the path member 10 opens downward and communicates with the space inside the primary heat exchanger 5. Also, the upper part of the path member 10 opens forward and communicates with the space inside the secondary heat exchanger 6.

[0023] The water heater 1 circulates the combustion exhaust gas generated by each lean-rich burner of the combustion device 4 to the primary heat exchanger 5 above the combustion device 4. In the primary heat exchanger 5, heat exchange is performed between the water flowing through the primary heat exchanger 5 and the combustion exhaust gas. The water heater 1 recovers the sensible heat of the combustion exhaust gas by the primary heat exchanger 5.

[0024] In the water heater 1, the combustion exhaust gas of the combustion device 4 is guided from the primary heat exchanger 5 through the path member 10 to the secondary heat exchanger 6. The combustion exhaust gas that has passed through the primary heat exchanger 5 enters the secondary heat exchanger 6 from the rear through the path member 10. That is, the secondary heat exchanger 6 is arranged on the downstream side of the path of the combustion exhaust gas with respect to the primary heat exchanger 5. In the secondary heat exchanger 6, heat exchange is performed between the water flowing through the secondary heat exchanger 6 and the combustion exhaust gas. The water heater 1 recovers the latent heat of the combustion exhaust gas by the secondary heat exchanger 6.

[0025] [Primary heat exchanger] The primary heat exchanger 5 is a sensible heat recovery type heat exchanger. The lower end of the primary heat exchanger 5 is connected to the combustion device 4, and the upper end is connected to the secondary heat exchanger 6. The primary heat exchanger 5 includes a primary casing 51 through which the combustion exhaust gas from the combustion device 4 passes, a plurality of heat transfer fins arranged in parallel at a predetermined interval in the front-rear direction which is the thickness direction inside the primary casing 51, and a primary heat transfer pipe 52 formed in a meandering shape through each heat transfer fin in the front-rear direction. The primary casing 51 has a rectangular tubular shape penetrating in the vertical direction. A hot water outlet pipe 13 is connected to the downstream end of the primary heat transfer pipe 52.

[0026] [Secondary heat exchanger] The secondary heat exchanger 6 is a latent heat recovery type heat exchanger. The combustion exhaust gas from the primary heat exchanger 5 is introduced into the secondary heat exchanger 6 through the path member 10. As shown in FIG. 11, the secondary heat exchanger 6 includes a secondary casing 61 through which the combustion exhaust gas from the primary heat exchanger 5 passes, and a plurality of secondary heat transfer pipes (an example of heat transfer pipes) 62 housed inside the secondary casing 61. The secondary heat exchanger 6 can be made of stainless steel with excellent corrosion resistance.

[0027] As shown in FIGS. 8 and 9, the secondary casing 61 includes a front wall portion 61A and a rear wall portion 61B disposed at both ends in the front-rear direction where the combustion exhaust gas is supplied, a pair of side wall portions 61C, 61D disposed at both ends in the left-right direction orthogonal to the front-rear direction, and a bottom wall portion 61E and a ceiling wall portion 61F disposed at both ends in the vertical direction orthogonal to the front-rear direction and the left-right direction.

[0028] Of the pair of side wall portions 61C, 61D, the one located on the left when viewed from the rear is the left side wall portion (an example of a side wall portion) 61C, and the one located on the right is the right side wall portion (an example of an opposing wall portion) 61D. The left side wall portion 61C and the right side wall portion 61D are disposed opposite to each other in the left-right direction.

[0029] On the ceiling wall portion 61F of the secondary casing 61, an exhaust pipe 66 for discharging the combustion exhaust gas inside the secondary casing 61 upward is provided. An exhaust pipe (not shown) disposed indoors is connected to the exhaust pipe 66, and the combustion exhaust gas is discharged outdoors through this exhaust pipe. Inside the secondary casing 61, a partition plate 63 is provided to vertically partition the arrangement region R1 of the secondary heat transfer pipes 62 and the lower region R2 of the ceiling wall portion 61F.

[0030] An inlet 64 penetrating in the front-rear direction is provided in the rear wall portion 61B. The inlet 64 is an opening for introducing the combustion exhaust gas into the inside of the secondary casing 61. On the other hand, an outlet 65 is provided between the front edge of the partition plate 63 and the front end portion of the ceiling wall portion 61F. The outlet 65 is an opening for discharging the combustion exhaust gas from the arrangement region R1 of the secondary heat transfer pipes 62 to the lower region R2 of the ceiling wall portion 61F. In the secondary heat exchanger 6, the combustion exhaust gas flows into the arrangement region R1 of the secondary heat transfer pipes 62 through the inlet 64, circulates through the arrangement region R1 from the rear to the front, goes upward along the front wall portion 61A, then changes its direction backward and flows out through the outlet 65 to the lower region R2 of the ceiling wall portion 61F, and is discharged to the outside of the secondary casing 61 through the exhaust pipe 66. That is, the combustion exhaust gas after the latent heat is recovered by the secondary heat exchanger 6 is discharged to the outside of the water heater 1 through the exhaust pipe 66 of the secondary casing 61 and is discharged outdoors through the exhaust pipe.

[0031] The plurality of secondary heat transfer pipes 62 are formed in a meandering shape as a whole, and as shown in FIG. 12, a plurality of straight pipe portions 62A arranged in the front-rear direction in a posture facing the left-right direction, and a plurality of return pipe portions 62B connecting one end portions and the other end portions in the left-right direction of the plurality of straight pipe portions 62A. The plurality of secondary heat transfer pipes 62 are stacked in the vertical direction and housed in the secondary casing 61. Both end portions of the secondary heat transfer pipes 62 are inserted and fixed to the left side wall portion 61C with a space in the front-rear direction.

[0032] On the side of the right side wall portion 61D, three folded pipe portions 62B are provided, and on the side of the left side wall portion 61C, two folded pipe portions 62B are provided. In the left side wall portion 61C, there are many pipes crossing the left side wall portion 61C, such as the portions of the straight pipe portion 62A connected to the headers 67A and 67B. Therefore, the exhaust resistance is higher than that on the right side wall portion 61D side.

[0033] A pair of headers 67A and 67B are provided on the left side wall portion 61C. Among the pair of headers 67A and 67B, the front one is the front header 67A, and the rear one is the rear header 67B. The front header 67A is the portion connecting the upstream end of the secondary heat transfer pipe 62 and the downstream end of the water inlet pipe 11. The rear header 67B is the portion connecting the downstream end of the secondary heat transfer pipe 62 and the upstream end of the relay pipe 12. The relay pipe 12 is a pipe that relays and connects the upstream end of the primary heat transfer pipe 52 of the primary heat exchanger 5 and the downstream end of the secondary heat transfer pipe 62 of the secondary heat exchanger 6.

[0034] [Flow deflection guide] As shown in FIG. 8, inside the secondary casing 61 of the secondary heat exchanger 6, a pair of front and rear flow deflection guides 69 are provided. The pair of flow deflection guides 69 are fixed to the right side wall portion 61D by brazing or the like. The pair of flow deflection guides 69 are of the same shape and size.

[0035] The flow deflection guide 69 includes a pair of protruding plates 69A arranged at intervals in the front-rear direction, and a fixing plate 69B that connects the pair of protruding plates 69A to each other and is fixed to the right side wall portion 61D, and is formed in a portal shape in plan view. The protruding plate 69A of Embodiment 1 protrudes toward the left side wall portion 61C in an arrangement perpendicular to the right side wall portion 61D, but it may protrude in an arrangement inclined at an arbitrary angle with respect to the right side wall portion 61D.

[0036] The protruding plate 69A of each flow deflection guide 69 is located upstream of the corresponding return pipe portion 62B. The corresponding return pipe portion 62B is the return pipe portion 62B located on the right side wall portion 61D side, and among the pair of return pipe portions 62B closest to the protruding plate 69A, it is the return pipe portion 62B located downstream of the protruding plate 69A. Therefore, each protruding plate 69A of the flow deflection guide 69 is provided upstream of the corresponding return pipe portion 62B. The flow deflection guide 69 is provided in such an arrangement that the pair of protruding plates 69A do not face the odd-numbered return pipe portions 62B on the right side wall portion 61D side when viewed from the upstream side in the front-rear direction, and surround the return pipe portion 62B from both sides in the front-rear direction. The fixed plate 69B of the flow deflection guide 69 faces the odd-numbered return pipe portions 62B and is fixed to the inner surface of the left side wall portion 61C so that the pair of protruding plates 69A sandwich the odd-numbered return pipe portions 62B from the upstream side and the downstream side. As a result, the protruding plates 69A are positioned upstream of the odd-numbered and even-numbered return pipe portions 62B.

[0037] [Communication portion] As shown in FIG. 7, a plurality of communication portions 63A are provided at positions excluding at least the end portion on the right side wall portion 61D side of the partition plate 63 to shortcut the combustion exhaust flowing through the arrangement region R1 of the secondary heat transfer pipes 62 to the lower region R2 of the ceiling wall portion 61F. The communication portions 63A are provided at the front end portion of the partition plate 63. The communication portions 63A are constituted by circular through-holes. The plurality of communication portions 63A are provided side by side at equal intervals in the left-right direction and are formed in two rows in the front-rear direction. The two-dot chain line in FIG. 12 indicates the positions of the communication portions 63A. The front-row communication portions 63A are provided at positions corresponding to the straight pipe portions 62A in the first row in front of the secondary heat transfer pipes 62 located at the uppermost stage in the front-rear direction, and the rear-row communication portions 63A are provided at positions corresponding to the straight pipe portions 62A in the second row in front.

[0038] [Airflow of combustion exhaust] Next, the airflow of the combustion exhaust will be described with reference to FIGS. 12 and 13. The combustion exhaust that has flowed into the secondary casing 61 through the inlet 64 collides with the straight tube portion 62A of the secondary heat transfer tube 62 from the rear as shown by the arrow line in FIG. 13, thereby performing heat exchange. The combustion exhaust flows from the rear to the front in the arrangement region R1 of the secondary heat transfer tube 62. During this time, it collides with a plurality of straight tube portions 62A and moves forward. After colliding with the front wall portion 61A, it changes its direction upward and heads towards the outlet 65. The combustion exhaust flows into the lower region R2 of the ceiling wall portion 61F through the outlet 65 and flows out of the secondary casing 61 through the exhaust pipe 66.

[0039] However, since the combustion exhaust tends to flow towards a location with low exhaust resistance, as shown by the arrow line F1 in FIG. 12, a part of the combustion exhaust heads towards the right side wall portion 61D and attempts to flow forward through the gap S1 formed between the right side wall portion 61D and the secondary heat transfer tube 62. Here, if the drift guide 69 is not provided, the combustion exhaust will flow straight forward through the gap S1, resulting in a decrease in heat exchange efficiency.

[0040] Therefore, in Embodiment 1, since the drift guide 69 is provided on the right side wall portion 61D, as shown by the arrow line F2 in FIG. 12, the combustion exhaust flowing along the right side wall portion 61D collides with the protruding plate 69A and drifts towards the left side wall portion 61C side. As a result, the amount of combustion exhaust flowing through the gap S1 decreases, and the amount of combustion exhaust flowing through the spaces between the plurality of straight tube portions 62A increases, improving the heat exchange efficiency.

[0041] In addition, a plurality of communication portions 63A are provided at the front end portion of the partition plate 63, and these communication portions 63A are arranged on the left side wall portion 61C side rather than on the gap S1 side. Therefore, the drift guide 69 makes it easier for the combustion exhaust to drift. That is, the combined effect of the drift guide 69 and the communication portions 63A can guide the airflow of the combustion exhaust shown by the arrow line F2 more towards the left side wall portion 61C side.

[0042] Furthermore, as shown by the arrow F3 in FIG. 12, a part of the combustion exhaust that flows linearly forward from the inlet 64 is discharged to the outside of the secondary casing 61 through the communication part 63A as shown by the arrow F4 in FIG. 13, so that the exhaust resistance of the combustion exhaust can be reduced. Therefore, it is possible to suppress the combustion exhaust from becoming difficult to flow in the secondary casing 61 and ensure the combustion performance of the combustion device 4.

[0043] [Operation and Effect of Embodiment 1] The secondary heat exchanger 6 of Embodiment 1 is a secondary heat exchanger 6 including a secondary casing 61 into which combustion exhaust is supplied and a plurality of secondary heat transfer tubes 62 housed inside the secondary casing 61. The secondary casing 61 includes a left side wall portion 61C disposed at one end in the left-right direction orthogonal to the front-rear direction in which combustion exhaust is supplied, and a right side wall portion 61D facing the left side wall portion 61C in the left-right direction. The plurality of secondary heat transfer tubes 62 are formed in a meandering shape as a whole, and include a plurality of straight tube portions 62A arranged in parallel in the front-rear direction in a posture facing the left-right direction, and a plurality of return tube portions 62B connecting one ends and the other ends in the left-right direction of the plurality of straight tube portions 62A. Both ends of the secondary heat transfer tube 62 are inserted and fixed to the left side wall portion 61C at intervals in the front-rear direction. A drift guide 69 for deflecting the combustion exhaust flowing along the right side wall portion 61D toward the left side wall portion 61C is provided on the right side wall portion 61D of the secondary casing 61. Since the drift guide 69 can deflect the combustion exhaust flowing along the right side wall portion 61D toward the left side wall portion 61C, it is possible to suppress the combustion exhaust from being discharged without being heat-exchanged.

[0044] The drift guide 69 has a protruding plate 69A protruding toward the left side wall portion 61C. With the simple configuration of the protruding plate 69A, the combustion exhaust can be guided.

[0045] The protruding plate 69A of the drift guide 69 is provided upstream of the return tube portion 62B located on the right side wall portion 61D side. The periphery of the return pipe portion 62B has more gaps than the periphery of the straight pipe portion 62A. On the other hand, since the protruding plate 69A is arranged on the upstream side of each return pipe portion 62B, it is possible to effectively suppress the combustion exhaust gas from flowing into the right side wall portion 61D side through the gap S1 around the return pipe portion 62B.

[0046] At least three return pipe portions 62B are provided on the right side wall portion 61D side. The flow deviation guide 69 includes a pair of protruding plates 69A arranged at intervals in the front-rear direction, and a fixing plate 69B that connects the pair of protruding plates 69A to each other and is fixed to the right side wall portion 61D. It is formed in a gate shape in plan view. The flow deviation guide 69 is arranged such that the pair of protruding plates 69A do not face the odd-numbered return pipe portions 62B on the right side wall portion 61D side when viewed from the upstream side in the front-rear direction among the three return pipe portions 62B, and surrounds the return pipe portion 62B from both sides in the front-rear direction. With the flow deviation guides 69 of the same shape, the protruding plates 69A can be arranged on the upstream side of all the return pipe portions 62B located on the right side wall portion 61D side, so that an increase in the number of parts can be prevented and incorrect assembly can be prevented.

[0047] An exhaust pipe 66 for discharging the combustion exhaust gas in the secondary casing 61 upward is provided on the ceiling wall portion 61F of the secondary casing 61. The exhaust pipe 66 is arranged at a position closer to the left from the right side wall portion 61D of the secondary heat exchanger 6, or at a position closer to the center in the left-right direction. Inside the secondary casing 61, a partition plate 63 is provided to partition the arrangement region R1 of the secondary heat transfer pipes 62 and the lower region R2 of the ceiling wall portion 61F in the vertical direction. A communication portion 63A is provided at a position excluding at least the end portion on the right side wall portion 61D side of the partition plate 63 to shortcut the combustion exhaust gas flowing through the arrangement region R1 of the secondary heat transfer pipes 62 to the lower region R2 of the ceiling wall portion 61F. By providing the communication portion 63A and arranging the exhaust pipe 66 on the downstream side further closer to the left side, the combustion exhaust gas can flow more easily toward the left side wall portion 61C side. Therefore, due to the synergistic effect with the flow deviation guide 69, the combustion exhaust gas flowing through the right side wall portion 61D side can be guided more favorably to the left side wall portion 61C side.

[0048] <Embodiment 2> Next, Embodiment 2 of the present disclosure will be described with reference to FIG. 14. The water heater 201 of Embodiment 2 includes a secondary heat exchanger 206 having a different form from the water heater 1 of Embodiment 1. Since the configurations other than the secondary heat exchanger 206 are the same as those of Embodiment 1, the description thereof will be omitted, and the same reference numerals as those in Embodiment 1 will be used for the same configurations as those in Embodiment 1.

[0049] The secondary heat exchanger 206 includes a secondary casing 230, a secondary heat exchanger 210 for hot water supply, and a secondary heat exchanger 220 for bath use. These secondary casing 230, secondary heat exchanger 210 for hot water supply, and secondary heat exchanger 220 for bath use can be made of stainless steel with excellent corrosion resistance.

[0050] Inside the secondary casing 230, a partition wall 231 is provided that separates and partitions the internal space of the secondary casing 230 in the left-right direction. The secondary heat exchanger 210 for hot water supply and the secondary heat exchanger 220 for bath use are arranged side by side in the left-right direction inside the secondary casing 230 via this partition wall 231. The secondary heat exchanger 206 is partitioned by the partition wall 231 into a secondary heat exchanger 210 for hot water supply on the left side of the partition wall 231 and a secondary heat exchanger 220 for bath use on the right side of the partition wall 231. The partition wall 231 is disposed between a left side wall portion 261C and a right side wall portion 261D, and is provided in an arrangement facing the respective side wall portions 261C and 261D in the left-right direction.

[0051] The secondary heat exchanger 210 for hot water supply is configured to have a plurality of secondary heat transfer pipes 211 for hot water supply. The secondary heat transfer pipes 211 for hot water supply are formed in a meandering shape as a whole, and include a plurality of straight pipe portions 211A arranged in parallel in the front-rear direction in a posture facing the left-right direction, and a plurality of return pipe portions 211B connecting one ends and the other ends in the left-right direction of the plurality of straight pipe portions 211A. The plurality of secondary heat transfer pipes 211 for hot water supply are stacked in the vertical direction and housed in the secondary casing 230. Each of the secondary heat transfer pipes 211 for hot water supply has one end and the other end that open to the left. Both ends of the secondary heat transfer pipes 211 for hot water supply are inserted and fixed to the left side wall portion 261C with a space in the front-rear direction. The secondary heat exchanger 210 for hot water supply performs heat exchange by passing water in parallel through each of the secondary heat transfer pipes 211 for hot water supply.

[0052] The secondary heat exchanger 220 for the bathtub is configured to have a plurality of secondary heat transfer pipes 221 for the bathtub in the same manner as the secondary heat exchanger 210 for hot water supply. The secondary heat transfer pipes 221 for the bathtub are formed in a meandering shape as a whole, and include a plurality of straight pipe portions 221A arranged in parallel in the front-rear direction in a posture facing the left-right direction, and a plurality of return pipe portions 221B connecting one ends and the other ends in the left-right direction of the plurality of straight pipe portions 221A. The plurality of secondary heat transfer pipes 221 for the bathtub are stacked in the vertical direction and housed in the secondary casing 230. Each of the secondary heat transfer pipes 221 for the bathtub has one end and the other end that open to the right. Both ends of the secondary heat transfer pipes 221 for the bathtub are inserted and fixed to the right side wall portion 261D with a space in the front-rear direction. The secondary heat exchanger 220 for the bathtub performs heat exchange by passing water in parallel through each of the secondary heat transfer pipes 221 for the bathtub.

[0053] The arrangement regions of the secondary heat transfer pipes 211 and 221 are partitioned by the partition wall 231 into an arrangement region R3 of the secondary heat transfer pipes 211 for hot water supply and an arrangement region R4 of the secondary heat transfer pipes 221 for the bathtub. In the arrangement region R3 of the secondary heat transfer pipes 211 for hot water supply, a pair of flow deflection guides 69 is provided in the front-rear direction. The pair of flow deflection guides 69 is fixed to the left side surface of the partition wall 231 by spot welding, brazing, or the like.

[0054] At least at a position excluding the end portion on the partition wall 231 side in the partition plate 63, a communication portion 263A is provided that shortcuts the combustion exhaust flowing through the arrangement region R3 of the secondary heat transfer pipe 211 for hot water supply to the lower region R2 of the ceiling wall portion 61F. In the second embodiment, since the drift guide 69 is provided on the left side surface of the partition wall 231, the combustion exhaust flowing into the secondary casing 230 from the inlet 264 heads toward the left side surface of the partition wall 231 and then, as shown by the arrow line F5 in FIG. 14, collides with the protruding plate 69A and heads toward the left side wall portion 261C side. Therefore, since the amount of combustion exhaust flowing through the gap S2 formed between the partition wall 231 and the secondary heat transfer pipe 211 for hot water supply is reduced, the heat exchange efficiency can be improved.

[0055] As described above, in the second embodiment, the side wall portions 261C and 261D are arranged in a pair at both end portions in the left - right direction in the secondary casing 230. The secondary casing 230 has a partition wall 231 that separates and partitions the internal space of the secondary casing 230 in the left - right direction. The opposing wall portion facing the left side wall portion 261C is the partition wall 231.

[0056] By separating and partitioning the internal space of the secondary casing 230 by the partition wall 231, even when the secondary heat exchanger 210 for hot water supply and the secondary heat exchanger 220 for the bathtub are configured as one heat exchanger, the drift guide 69 can cause the combustion exhaust flowing along the partition wall 231 to drift toward the left side wall portion 261C side.

[0057] <Other Embodiments> The present disclosure is not limited to the embodiments described by the above description and drawings. For example, the features of the above - described or below - described embodiments can be combined in any non - conflicting range. Also, any feature of the above - described or below - described embodiments can be omitted if it is not explicitly stated as essential. Furthermore, the above - described embodiments may be modified as follows.

[0058] (1) In Embodiments 1 and 2, an example is given in which the fixed plate 69B of the drift guide 69 is configured to connect the pair of protruding plates 69A. However, one fixed plate 69B may be provided for each protruding plate 69A, and the drift guide may be configured so as to form an L shape in plan view as a whole.

[0059] (2) In Embodiments 1 and 2, an example is given in which the protruding plate 69A is provided in an arrangement not facing the bent pipe portion 62B. However, the protruding plate may be provided in an arrangement facing the bent pipe portion 62B.

[0060] (3) In Embodiments 1 and 2, an example is given in which the drift guide 69 is configured separately from the left side wall portion 61C or the partition wall 231. However, the drift guide may be configured integrally with the left side wall portion 61C or the partition wall 231.

Explanation of Reference Numerals

[0061] 1, 201: Water heater 2: Housing 3: Inner cylinder 4: Combustion device 5: Primary heat exchanger 6, 206: Secondary heat exchanger 7: Gas supply unit 8: Intake fan 9: Controller 10: Path member 11: Water inlet pipe 12: Relay pipe 13: Hot water outlet pipe 14: Drain hose 41: Inner case 51: Primary casing 52: Primary heat transfer pipe 61: Secondary casing 61A: Front wall portion 61B: Rear wall portion 61C: Left side wall portion (side wall portion) 61D: Right side wall portion (opposing wall portion) 61E: Bottom wall portion 61F: Ceiling wall portion 62: Secondary heat transfer pipe 62A: Straight pipe portion 62B: Bent pipe portion 63: Partition plate 63A: Communication portion 64: Inlet 65: Outlet 66: Exhaust pipe 67A: Front header 67B: Rear header 68: Drain outlet 69: Drift guide 69A: Protruding plate 69B: Fixed plate 210: Domestic hot water secondary heat exchanger 211: Domestic hot water secondary heat transfer pipe 211A: Straight pipe portion 211B: Bent pipe portion 220: Bath secondary heat exchanger 221: Bath secondary heat transfer pipe 221A: Straight pipe portion 221B: Bent pipe portion 230: Secondary casing 231: Partition wall 261C: Left side wall portion 261D: Right side wall portion 263A: Communication portion 264: Inlet R1: Arrangement area of the secondary heat transfer pipe 62 R2: Lower area of the ceiling wall portion 61F R3: Arrangement area of the secondary heat transfer pipe 211 for hot water supply R4: Arrangement area of the secondary heat transfer pipe 221 for bathtub S1: Gap S2: Gap

Claims

1. A heat exchanger comprising a casing into which combustion exhaust is supplied, and a plurality of heat transfer tubes accommodated inside the casing, wherein: the casing includes a side wall portion disposed at one end in a second direction orthogonal to a first direction in which the combustion exhaust is supplied, and an opposing wall portion opposing the side wall portion in the second direction; the plurality of heat transfer tubes are formed in a meandering shape as a whole, and include a plurality of straight tube portions arranged in parallel in the first direction in a posture facing the second direction, and a plurality of return tube portions connecting one ends and the other ends of the plurality of straight tube portions in the second direction, and both ends of the heat transfer tubes are inserted and fixed to the side wall portion with a space therebetween in the first direction; a flow deflection guide for deflecting the combustion exhaust flowing along the opposing wall portion toward the side wall portion is provided on the opposing wall portion of the casing; the flow deflection guide has a protruding plate protruding toward the side wall portion; the protruding plate of the flow deflection guide is provided upstream of the return tube portion located on the opposing wall portion side, the heat exchanger.

2. A heat exchanger comprising a casing into which combustion exhaust is supplied, and a plurality of heat transfer tubes accommodated inside the casing, wherein: the casing includes a side wall portion disposed at one end in a second direction orthogonal to a first direction in which the combustion exhaust is supplied, and an opposing wall portion opposing the side wall portion in the second direction; the plurality of heat transfer tubes are formed in a meandering shape as a whole, and include a plurality of straight tube portions arranged in parallel in the first direction in a posture facing the second direction, and a plurality of return tube portions connecting one ends and the other ends of the plurality of straight tube portions in the second direction, and both ends of the heat transfer tubes are inserted and fixed to the side wall portion with a space therebetween in the first direction; a flow deflection guide for deflecting the combustion exhaust flowing along the opposing wall portion toward the side wall portion is provided on the opposing wall portion of the casing; the flow deflection guide has a protruding plate protruding toward the side wall portion; at least three return tube portions are provided on the opposing wall portion side; the flow deflection guide includes a pair of protruding plates arranged with a space therebetween in the first direction, and a fixing plate connecting the pair of protruding plates and fixed to the opposing wall portion, and is formed in a gate shape in plan view. The offset flow guide is a heat exchanger provided in such an arrangement that the pair of protruding plates do not face the return pipe portions on the side of the opposing wall portions that are the odd-numbered ones when viewed from the upstream side in the first direction among the three return pipe portions, and that the return pipe portions are surrounded from both sides in the first direction. **Claim 3**: A heat exchanger comprising a casing into which combustion exhaust gas is supplied, and a plurality of heat transfer pipes housed inside the casing, wherein the casing includes a side wall portion disposed at one end in a second direction orthogonal to a first direction in which the combustion exhaust gas is supplied, and an opposing wall portion facing the side wall portion in the second direction, the plurality of heat transfer pipes are formed in a meandering shape as a whole, and include a plurality of straight pipe portions arranged in parallel in the first direction in a posture facing the second direction, and a plurality of return pipe portions connecting one ends and the other ends in the second direction of the plurality of straight pipe portions, and both ends of the heat transfer pipes are inserted and fixed to the side wall portion with a space therebetween in the first direction, an offset flow guide for deflecting the combustion exhaust gas flowing along the opposing wall portion toward the side wall portion is provided on the opposing wall portion of the casing, the offset flow guide has a protruding plate protruding toward the side wall portion, an exhaust pipe for discharging the combustion exhaust gas inside the casing upward is provided on a ceiling wall portion of the casing, and a partition plate for vertically partitioning a region where the heat transfer pipes are arranged and a lower region of the ceiling wall portion is provided inside the casing, a heat exchanger provided with a communication portion for shortcutting the combustion exhaust gas flowing through the region where the heat transfer pipes are arranged to the lower region of the ceiling wall portion at a position excluding at least an end portion on the side of the opposing wall portion in the partition plate. **Claim 4** At least three return pipe portions are provided on the side of the opposing wall portion. The offset flow guide includes a pair of the protruding plates arranged at intervals in the first direction, and a fixing plate that connects the pair of protruding plates and is fixed to the opposing wall portion, and is formed in a gate shape in plan view. The offset flow guide is provided in such an arrangement that the pair of protruding plates do not face the return pipe portions on the side of the opposing wall portions that are the odd-numbered ones when viewed from the upstream side in the first direction among the three return pipe portions, and that the return pipe portions are surrounded from both sides in the first direction. The heat exchanger according to claim 1. **Claim 5** An exhaust pipe for discharging the combustion exhaust gas in the casing upward is provided on the ceiling wall portion of the casing, and a partition plate for partitioning the arrangement region of the heat transfer pipe and the lower region of the ceiling wall portion vertically is provided inside the casing. A communication portion for shortcutting the combustion exhaust gas flowing through the arrangement region of the heat transfer pipe to the lower region of the ceiling wall portion is provided at a position excluding at least the end portion on the opposing wall portion side of the partition plate. The heat exchanger according to claim 1, claim 2, or claim 4.

6. The side wall portions are arranged in a pair at both ends of the casing in the second direction, the casing has a partition wall for separating and partitioning the internal space of the casing in the second direction, and the opposing wall portion is the partition wall. The heat exchanger according to any one of claims 1 to 5.

7. A combustion device, A primary heat exchanger provided continuously with the combustion device and through which the combustion exhaust gas from the combustion device passes, A water heater including a secondary heat exchanger which is provided continuously with the primary heat exchanger and through which the combustion exhaust gas from the primary heat exchanger passes, and which is the heat exchanger according to any one of claims 1 to 6.

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