Water heater manufacturing method

Abstract

To provide a sensible heat recovery type water heater, a latent heat recovery type water heater and a manufacturing method of the water heaters capable of suppressing cost of manufacture thereof.SOLUTION: A sensible heat recovery type water heater 3 includes: a burner device 300; a primary heat exchanger 100 fixed to an upper part of the burner device 300 and to recover sensible heat from combustion exhaust generated from the burner device 300; and an exhaust casing 290 disposed at a downstream side of the primary heat exchanger 100 and to discharge combustion exhaust discharged from the primary heat exchanger 100, wherein the exhaust casing 290 is configured by using a box body 291 that has an inflow port 245 at a rear side for receiving the combustion exhaust and has an outflow port 246 at a front side for discharging the combustion exhaust, and the box body 291 is used for a housing 230 of a secondary heat exchanger 200 in a latent heat recovery type water heater 2 that includes; the burner device 300; the primary heat exchanger 100; and the secondary heat exchanger 200 disposed at the downstream side of the primary heat exchanger 100 and to recover latent heat from the combustion exhaust discharged from the primary heat exchanger 100.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a sensible heat recovery water heater, a latent heat recovery water heater, and a method for manufacturing a water heater. [Background technology]

[0002] Conventionally, a water heater of sensible heat recovery type is known, for example, from the water heater described in Japanese Patent Laid-Open No. 2018-31489 (Patent Document 1 below). The water heater of Patent Document 1 includes a burner unit, a heat exchanger, and an exhaust casing. The heat exchanger recovers sensible heat from the combustion exhaust gas generated by the burner unit. The combustion exhaust gas that passes through the heat exchanger is discharged to the outside through the exhaust casing. Furthermore, a water heater described in Japanese Patent Application Laid-Open No. 2021-55888 (Patent Document 2 below) is known as a conventional latent heat recovery water heater. The water heater of Patent Document 2 includes a burner device, a primary heat exchanger, and a secondary heat exchanger. The primary heat exchanger recovers sensible heat from the combustion exhaust gas generated by the burner device. The secondary heat exchanger recovers latent heat from the combustion exhaust gas that has passed through the primary heat exchanger. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-31489 [Patent Document 2] Patent Publication No. 2021-55888 Summary of the Invention [Problem to be solved by the invention]

[0004] Sensible heat recovery water heaters like the one described above are often designed at the same time as latent heat recovery water heaters as a variation of the latter, and most of the parts are shared between the sensible heat recovery water heater and the latent heat recovery water heater. However, the exhaust casing of a sensible heat recovery water heater is often individually designed and manufactured using a newly created mold. For this reason, if the production lot number of sensible heat recovery water heaters is small, it can be difficult to keep manufacturing costs down.

[0005] The present disclosure was completed based on the above circumstances, and aims to provide a sensible heat recovery water heater, a latent heat recovery water heater, and a method for manufacturing a water heater that can reduce manufacturing costs. [Means for solving the problem]

[0006] The sensible heat recovery water heater of the present disclosure is a sensible heat recovery water heater comprising: a combustion device; a primary heat exchanger fixed to the top of the combustion device and recovering sensible heat from the combustion exhaust gas generated by the combustion device; and an exhaust casing arranged downstream of the primary heat exchanger and discharging the combustion exhaust gas discharged from the primary heat exchanger to the outside, wherein the exhaust casing is constructed using a box body having an inlet portion at the rear for receiving the combustion exhaust gas and an outlet portion at the front for discharging the combustion exhaust gas, and the box body is used as the housing of the secondary heat exchanger in a latent heat recovery water heater comprising the combustion device, the primary heat exchanger, and a secondary heat exchanger arranged downstream of the primary heat exchanger and recovering latent heat from the combustion exhaust gas discharged from the primary heat exchanger. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a sensible heat recovery water heater, a latent heat recovery water heater, and a method for manufacturing a water heater that can reduce manufacturing costs. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a front view illustrating a schematic example of the internal structure of a latent heat recovery water heater according to an embodiment. [Figure 2] FIG. 2 is an explanatory diagram conceptually illustrating the configuration of a latent heat recovery water heater. [Figure 3] FIG. 3 is a partially enlarged cross-sectional view taken along line AA in FIG. [Figure 4] FIG. 4 is a partially enlarged cross-sectional view showing a main part of the secondary heat exchanger. [Figure 5] FIG. 5 is an enlarged partial cross-sectional view taken along line BB in FIG. [Figure 6] FIG. 6 is a partially enlarged perspective view illustrating a schematic example of the internal structure of a latent heat recovery water heater. [Figure 7] FIG. 7 is a partially enlarged cross-sectional view taken along line CC in FIG. [Figure 8] FIG. 8 is a perspective view that schematically illustrates a secondary heat exchanger. [Figure 9] FIG. 9 is an exploded perspective view that schematically illustrates the housing of the secondary heat exchanger. [Figure 10] FIG. 10 is an explanatory diagram illustrating a state before the first assembly and the second assembly are attached to the main body. [Figure 11] FIG. 11 is a front view illustrating a schematic example of the internal structure of a sensible heat recovery water heater. [Figure 12] FIG. 12 is an explanatory diagram conceptually illustrating the configuration of a sensible heat recovery water heater. [Figure 13] FIG. 13 is a partially enlarged cross-sectional view taken along line DD in FIG. [Figure 14] FIG. 14 is an exploded perspective view schematically illustrating an exhaust casing of a sensible heat recovery water heater. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described.

[0010] (1) The sensible heat recovery water heater of the present disclosure is a sensible heat recovery water heater comprising: a combustion device; a primary heat exchanger fixed to the top of the combustion device and recovering sensible heat from the combustion exhaust gas generated by the combustion device; and an exhaust casing arranged downstream of the primary heat exchanger and discharging the combustion exhaust gas discharged from the primary heat exchanger to the outside, wherein the exhaust casing is constructed using a box body having an inlet portion at the rear for receiving the combustion exhaust gas and an outlet portion at the front for discharging the combustion exhaust gas, and the box body is used as a housing for the secondary heat exchanger in a latent heat recovery water heater comprising the combustion device, the primary heat exchanger, and a secondary heat exchanger arranged downstream of the primary heat exchanger and recovering latent heat from the combustion exhaust gas discharged from the primary heat exchanger.

[0011] (2) The latent heat recovery water heater of the present disclosure is a latent heat recovery water heater comprising: a combustion device; a primary heat exchanger fixed to the top of the combustion device and recovering sensible heat from the combustion exhaust gas generated by the combustion device; and a secondary heat exchanger arranged downstream of the primary heat exchanger and recovering latent heat from the combustion exhaust gas discharged from the primary heat exchanger, wherein the housing of the secondary heat exchanger is constructed using a box body having an inlet portion at the rear for receiving the combustion exhaust gas and an outlet portion at the front for discharging the combustion exhaust gas, and the box body is used for the exhaust casing in a sensible heat recovery water heater comprising the combustion device, the primary heat exchanger, and an exhaust casing arranged downstream of the primary heat exchanger and discharging the combustion exhaust gas discharged from the primary heat exchanger to the outside.

[0012] With this configuration, the exhaust casing of the sensible heat recovery water heater and the housing of the secondary heat exchanger of the latent heat recovery water heater are constructed from a common box. This eliminates the need to separately manufacture a mold for the exhaust casing of the sensible heat recovery water heater, making it possible to reduce manufacturing costs even when the production lot size of sensible heat recovery water heaters is small.

[0013] Furthermore, when the exhaust casing is designed individually, it is necessary to verify the ability to assemble the exhaust casing with other parts. However, in the above configuration, the exhaust casing and the housing of the secondary heat exchanger are constructed from the same box body, so the process of verifying the ability to assemble the exhaust casing or the housing of the secondary heat exchanger with other parts can be minimized. When assembling the exhaust casing or the housing of the secondary heat exchanger with other components, packing is placed between the edges of the inlet and outlet of the exhaust casing or the housing of the secondary heat exchanger and the other components to prevent the passage of gas. Because the exhaust casing and the housing of the secondary heat exchanger are formed from a common box body having an inlet and an outlet, the packing can also be common between the exhaust casing and the housing of the secondary heat exchanger.

[0014] (3) The method for manufacturing a water heater disclosed herein is a method for manufacturing a water heater including a combustion device and a primary heat exchanger fixed to an upper part of the combustion device and recovering sensible heat from the combustion exhaust gas generated by the combustion device, wherein the water heater includes a latent heat recovery water heater further including a secondary heat exchanger that recovers latent heat from the combustion exhaust gas discharged from the primary heat exchanger, and a sensible heat recovery water heater further including an exhaust casing that discharges the combustion exhaust gas discharged from the primary heat exchanger to the outside, and the method for manufacturing the water heater includes a step of forming a box body having an inlet portion at the rear for receiving the combustion exhaust gas and an outlet portion at the front for discharging the combustion exhaust gas, and if the water heater is the latent heat recovery water heater, further includes a step of forming a housing for the secondary heat exchanger by providing openings on both side surfaces of the box body, and a step of inserting multiple heat transfer tubes into the housing through the openings, and if the water heater is the sensible heat recovery water heater, further includes a step of forming the exhaust casing using the box body.

[0015] The method for manufacturing the water heater includes a step of forming a box body and a step of using the box body to construct a housing for a secondary heat exchanger of a latent heat recovery water heater or an exhaust casing of a sensible heat recovery water heater. Therefore, it is not necessary to separately manufacture a mold for the exhaust casing of the sensible heat recovery water heater, and it is possible to reduce manufacturing costs even when the production lot number of sensible heat recovery water heaters is small.

[0016] Furthermore, when the exhaust casing is designed separately, it is necessary to verify the ability to assemble the exhaust casing with other parts. However, in the above-described water heater manufacturing method, the exhaust casing and the secondary heat exchanger housing are constructed from the same box body, so the process of verifying the ability to assemble the exhaust casing or the secondary heat exchanger housing with other parts can be minimized. Furthermore, since the exhaust casing and the housing of the secondary heat exchanger have the same inlet and outlet portions, the gaskets placed between the rims of the inlet and outlet portions and other parts can be made common between the exhaust casing and the housing of the secondary heat exchanger.

[0017] <Embodiment> Hereinafter, an embodiment will be described with reference to the drawings. A water heater 1 of this embodiment includes a latent heat recovery water heater 2 and a sensible heat recovery water heater 3. First, the latent heat recovery water heater 2 will be described with reference to Figs. 1 to 10, and then the sensible heat recovery water heater 3 will be described with reference to Figs. 11 to 14. Note that, for multiple identical components, only some of the components will be assigned reference numerals, and the reference numerals of the other components may be omitted.

[0018] [Overall configuration of latent heat recovery water heater] As shown in FIGS. 1 to 3, the latent heat recovery water heater 2 includes a primary heat exchanger 100, a secondary heat exchanger 200, a burner device 300 (an example of a combustion device), and an exhaust hood 400.

[0019] The primary heat exchanger 100 includes two heat exchangers: a hot water supply primary heat exchanger 110 and a bath primary heat exchanger 120 .

[0020] The secondary heat exchanger 200 is disposed above the primary heat exchanger 100. The secondary heat exchanger 200 includes two heat exchangers: a hot water supply secondary heat exchanger 210 connected to the upstream side of the hot water supply primary heat exchanger 110, and a bath secondary heat exchanger 220 connected to the upstream side of the bath primary heat exchanger 120.

[0021] The burner device 300 is connected to the lower part of the primary heat exchanger 100. The burner device 300 comprises two burner groups, a hot water supply burner group 310 and a bathtub burner group 320, and a burner case 330. The hot water supply burner group 310 generates combustion exhaust gas to be sent to the hot water supply primary heat exchanger 110 and the hot water supply secondary heat exchanger 210. The bathtub burner group 320 generates combustion exhaust gas to be sent to the bathtub primary heat exchanger 120 and the bathtub secondary heat exchanger 220.

[0022] The exhaust hood 400 has a lower end connected to the primary heat exchanger 100 and an upper end connected to the secondary heat exchanger 200. The lower end of the exhaust hood 400 opens downward and communicates with the space inside the primary heat exchanger 100. The upper end of the exhaust hood 400 opens forward and communicates with the space inside the secondary heat exchanger 200.

[0023] The latent heat recovery water heater 2 circulates the combustion exhaust gas generated by each burner group 310, 320 of the burner device 300 through the primary heat exchanger 100 above the burner device 300. In the primary heat exchanger 100, heat is exchanged between the combustion exhaust gas and the water flowing through the hot water supply primary heat exchanger 110 and the bath primary heat exchanger 120. The latent heat recovery water heater 2 functions to recover sensible heat from the combustion exhaust gas using the primary heat exchanger 100.

[0024] In the latent heat recovery water heater 2, the combustion exhaust gas from the burner device 300 is guided from the primary heat exchanger 100 through the exhaust hood 400 to the secondary heat exchanger 200. The combustion exhaust gas that has passed through the primary heat exchanger 100 passes through the exhaust hood 400 and enters the secondary heat exchanger 200 from the rear. In other words, the secondary heat exchanger 200 is disposed downstream of the primary heat exchanger 100 in the path of the combustion exhaust gas. The secondary heat exchanger 200 exchanges heat between the water passing through the hot water supply secondary heat exchanger 210 and the bath secondary heat exchanger 220 and the combustion exhaust gas. The latent heat recovery water heater 2 functions to recover the latent heat of the combustion exhaust gas using the secondary heat exchanger 200.

[0025] [Circuit configuration of latent heat recovery water heater] As shown in FIG. 2, the latent heat recovery water heater 2 is configured to include two circuits: a hot water supply circuit 10 and a bath circuit 20.

[0026] 1 and 2, in the hot water supply circuit 10, water flows into a water inlet pipe 12 from a water inlet 11 connected to a water supply source such as a water supply, passes through a hot water secondary heat exchanger 210 and a hot water primary heat exchanger 110 in this order, and is heated by heat exchange with the combustion exhaust gas from a hot water supply burner group 310. The water then flows through a hot water outlet pipe 13 and flows out from a hot water outlet 14.

[0027] The bath circuit 20 is a circuit that circulates and heats the hot water in the bathtub B. The bath circuit 20 uses a circulation pump P to draw the hot water in the bathtub B into the return pipe 22 from the hot water inlet 21 that is connected to an opening in the bathtub B, and passes the water through the bath secondary heat exchanger 220 and the bath primary heat exchanger 120 in that order, exchanging heat with the combustion exhaust from the bath burner group 320 to reheat the hot water. The hot water, now at a higher temperature, is then discharged into the bathtub B from the hot water outlet 24 via the supply pipe 23.

[0028] 1 and 2, the latent heat recovery water heater 2 includes a drain hose 31 and a neutralizer 32. The upstream side of the drain hose 31 is connected to a drain outlet 251 (see FIG. 4) of the secondary heat exchanger 200, which will be described later, and the downstream side of the drain hose 31 is connected to the neutralizer 32. Drain generated by the recovery of latent heat in the secondary heat exchanger 200 is discharged to the outside of the secondary heat exchanger 200 via the drain outlet 251 and is sent to the neutralizer 32 through the drain hose 31.

[0029] As shown in FIG. 1 , the latent heat recovery water heater 2 includes a controller 33 as a control device. The controller 33 is configured, for example, as a known microcomputer or the like, and is configured to acquire signals from various sensors provided in the latent heat recovery water heater 2 and to control various actuators provided in the latent heat recovery water heater 2. For example, when the latent heat recovery water heater 2 detects water flow in the water inlet pipe 12 using a water flow sensor (not shown), it operates the hot water burner group 310 to generate hot water. As another example, when the latent heat recovery water heater 2 detects water flow in the return pipe 22 using a water flow sensor (not shown), it operates the bath burner group 320 to reheat the bath.

[0030] [Primary heat exchanger] Next, the configuration of the primary heat exchanger 100 will be described. The primary heat exchanger 100 is a sensible heat recovery type heat exchanger. As shown in Figures 3 and 5, the primary heat exchanger 100 is composed of a water heater body 130, a hot water supply primary heat exchanger 110, and a bath primary heat exchanger 120. The water heater body 130, the hot water supply primary heat exchanger 110, and the bath primary heat exchanger 120 can be made of copper, for example, which has excellent thermal conductivity.

[0031] As shown in Fig. 5, the can body 130 has a generally rectangular shape in a plan view that is long in the left-right direction, and is formed into a cylindrical shape that is perforated vertically. The inside of the can body 130 is divided into left and right halves by a partition 131. The primary heat exchanger 100 is divided by the partition 131 into a hot water supply primary heat exchanger 110 on the right side of the partition 131 and a bath primary heat exchanger 120 on the left side of the partition 131.

[0032] The hot water supply primary heat exchanger 110 includes a plurality of first heat transfer pipes 111 and a plurality of connection pipes 112 that connect these together.

[0033] The first heat transfer tube 111 is a straight tube with a circular cross section. A plurality of first heat transfer tubes 111 (seven in this embodiment) are provided. Each first heat transfer tube 111 is arranged extending in the front-to-rear direction with both ends penetrating the front and rear surfaces of the can body 130. Each first heat transfer tube 111 is fixed to the penetrating portion of the can body 130 by brazing or the like. The first heat transfer tubes 111 are arranged side by side in the left-to-right direction in the right-side space partitioned by the partition section 131. The front ends or rear ends of two adjacent first heat transfer tubes 111 are connected by a connecting tube 112, so that the multiple first heat transfer tubes 111 are connected in a serpentine manner.

[0034] The opening at the rear end of the first heat transfer pipe 111 farthest from the partition 131 is a hot water supply inlet opening 114 through which water from the hot water supply secondary heat exchanger 210 flows in. The opening at the front end of the first heat transfer pipe 111 closest to the partition 131 is a hot water supply outlet opening 115 through which heated water flows out. That is, in the hot water supply primary heat exchanger 110, water that flows in from the rear side of the right side of the boiler body 130 meanders in a direction approaching the partition 131 and flows out to the front side. One end of a hot water supply relay pipe 15 is connected to the hot water supply inlet opening 114. The other end of the hot water supply relay pipe 15 is connected to the outlet of the hot water supply secondary heat exchanger 210, which will be described later. A hot water outlet pipe 13 is connected to the hot water supply outlet opening 115.

[0035] The bath primary heat exchanger 120 is equipped with a plurality of first heat transfer pipes 121 and a plurality of connecting pipes 122 similar to the first heat transfer pipes 111 and connecting pipes 112 of the hot water supply primary heat exchanger 110. The bath primary heat exchanger 120 is equipped with a plurality of first heat transfer pipes 121 (three in this embodiment). The plurality of first heat transfer pipes 121 are arranged extending in the front-to-rear direction, and both ends are fixed to the front and rear surfaces of the water heater body 130, respectively. The first heat transfer pipes 121 are arranged side by side in the left-to-right direction in the left-side space partitioned by the partition section 131. The front ends or rear ends of two adjacent first heat transfer pipes 121 are connected by the connecting pipe 122, so that the plurality of first heat transfer pipes 121 are connected in a serpentine manner.

[0036] The opening at the front end of the first heat transfer pipe 121 closest to the partition 131 is designated as the bath inlet opening 124, through which water from the bath secondary heat exchanger 220 flows in. The opening at the rear end of the first heat transfer pipe 121 farthest from the partition 131 is designated as the bath outlet opening 125, through which heated water flows out. That is, in the bath primary heat exchanger 120, water flows in from the front side near the partition 131, meandering in a direction away from the partition 131, and flows out to the rear side. One end of the bath relay pipe 40 is connected to the bath inlet opening 124. The other end of the bath relay pipe 40 is connected to the outlet of the bath secondary heat exchanger 220, which will be described later. A supply pipe 23 is connected to the bath outlet opening 125.

[0037] [Secondary heat exchanger] Next, the configuration of the secondary heat exchanger 200 will be described. The secondary heat exchanger 200 is a latent heat recovery type heat exchanger. As shown in Fig. 3, the secondary heat exchanger 200 is disposed above the primary heat exchanger 100. The secondary heat exchanger 200 and the primary heat exchanger 100 are connected by an exhaust hood 400 (described later) for introducing the combustion exhaust gas that has passed through the primary heat exchanger 100 into the secondary heat exchanger 200.

[0038] 7 and 8, the secondary heat exchanger 200 is configured to have a housing 230, a hot water supply secondary heat exchanger 210, and a bath secondary heat exchanger 220. The housing 230, the hot water supply secondary heat exchanger 210, and the bath secondary heat exchanger 220 can be made of stainless steel, which has excellent corrosion resistance.

[0039] A partition 231 is provided inside the housing 230 to divide the internal space of the housing 230 into left and right sections. The hot water supply secondary heat exchanger 210 and the bath secondary heat exchanger 220 are arranged side by side in the left-right direction within the housing 230 via this partition 231. The secondary heat exchanger 200 is divided by the partition 231 into the hot water supply secondary heat exchanger 210 on the right side of the partition 231 and the bath secondary heat exchanger 220 on the left side of the partition 231.

[0040] As shown in Fig. 9, the housing 230 includes a main body 232 having a box shape that is long in the left-right direction, a lid 233, and a packing 234. An upper opening 235 is provided at the upper end of the main body 232. The lid 233 is attached to the main body 232 so as to close the upper opening 235 from above. The packing 234 is interposed between the main body 232 and the lid 233, and prevents gas from passing between the main body 232 and the lid 233. The main body 232 can be formed by processing a box 291 (see Fig. 14), which will be described later.

[0041] The main body 232 includes a bottom wall 240, a first wall 241, a second wall 242, a third wall 243, and a fourth wall 244. The first wall 241 is provided to rise upward from the front end of the bottom wall 240. The second wall 242 is provided to rise upward from the rear end of the bottom wall 240. The third wall 243 is provided to rise upward from the right end of the bottom wall 240 and connects the right ends of the first wall 241 and the second wall 242. The fourth wall 244 is provided to rise upward from the left end of the bottom wall 240 and connects the left ends of the first wall 241 and the second wall 242.

[0042] The second wall portion 242 is provided with an inlet 245 (an example of an inlet portion) that penetrates in the front-rear direction. The inlet 245 is an opening for introducing the combustion exhaust gas into the interior of the housing 230. Two inlet ports 245 are provided, the right one for introducing the combustion exhaust gas into the hot water supply secondary heat exchanger 210 and the left one for introducing the combustion exhaust gas into the bath secondary heat exchanger 220. The first wall portion 241 is provided with an outlet 246 (an example of an outlet portion) that penetrates in the front-rear direction. The outlet 246 is an opening for discharging the combustion exhaust gas from inside the housing 230. That is, in the secondary heat exchanger 200, the combustion exhaust gas flows through the housing 230 from rear to front. A plurality of connecting portions 242A are formed around the inlet 245 in the second wall portion 242. The connecting portion 242A has an internal thread shape and is used to attach an exhaust hood 400 (described later). A plurality of connected portions 241A are formed around the outlet 246 in the first wall portion 241. The connected portions 241A have an internal thread shape and are used to attach an exhaust tube 500, which will be described later.

[0043] A right opening 247 penetrating in the left-right direction is provided in the third wall portion 243. The right opening 247 is an opening for accommodating a plurality of second heat transfer tubes 211 (first assembly 281) assembled with the closing member 260A inside the housing 230. A plurality of connected portions 243A are formed around the right opening 247 in the third wall portion 243. The connected portions 243A are female-threaded and are used to attach the closing member 260A described below.

[0044] A left opening 248 penetrating in the left-right direction is provided in the fourth wall portion 244. The left opening 248 is an opening for accommodating a plurality of second heat transfer tubes 221 (second assembly 282) assembled with the closing member 260B inside the housing 230. A plurality of connected portions 244A are formed around the left opening 248 in the fourth wall portion 244. The connected portions 244A are female-threaded and are used to attach the closing member 260B described below.

[0045] The bottom wall 240 has a protruding portion 249 and a groove 250. The protruding portion 249 is located approximately in the center of the bottom wall 240 and protrudes upward relative to the groove 250. The groove 250 is provided around the protruding portion 249 and forms the outer periphery of the bottom wall 240. A drain outlet 251 that penetrates the bottom wall 240 in the up-down direction is formed in front of the groove 250. The drain outlet 251 is provided at a position corresponding to the partition 231. The drain outlet 251 is connected to a drain hose 31 (see FIG. 3). Drainage generated by the recovery of latent heat is discharged from the drain outlet 251 via the drain hose 31. The bottom wall 240 is arranged so as to tilt downward as it approaches the front.

[0046] As shown in FIGS. 6 to 8 and 10, a closing member 260A, and a first header 265A and a second header 270A attached to the closing member 260A are provided on the right side of the housing 230. As shown in FIG. 10, the closing member 260A is a plate-shaped member that closes the right opening 247 of the third wall portion 243. The closing member 260A has a plate-shaped portion 261, a plurality of (seven in this embodiment) first through holes 262, a plurality of (seven in this embodiment) second through holes 263, and a plurality of insertion holes 264. The first through holes 262, the second through holes 263, and the insertion holes 264 are provided so as to penetrate the plate-shaped portion 261 in the left-right direction. The plurality of first through holes 262 and the plurality of second through holes 263 are arranged spaced apart in the front-rear direction. The plurality of first through holes 262 are arranged on the front side of the plate-shaped portion 261, and the plurality of second through holes 263 are arranged on the rear side of the plate-shaped portion 261. The insertion holes 264 are holes through which the connecting member 243B (see FIG. 8) is inserted, and are arranged near the outer edge of the closing member 260A. The insertion hole 264 is provided at a position corresponding to the connected portion 243A. The connecting member 243B is inserted into the insertion hole 264 and connected to the connected portion 243A, thereby fixing the closing member 260A to the third wall portion 243. An annular packing (not shown) is provided between the third wall portion 243 and the closing member 260A. This prevents gas from passing between the third wall portion 243 and the closing member 260A.

[0047] As shown in Fig. 6, first header 265A is a portion that connects the inlet of hot water supply secondary heat exchanger 210 to the downstream side of water inlet pipe 12. As shown in Fig. 7, first header 265A has a first header main body 266, a first header cover 267 that covers the opening of first header main body 266, and hot water supply inlet portion 268. Hot water supply inlet portion 268 is connected to the downstream side of water inlet pipe 12.

[0048] The second header 270A is a portion that connects the outlet of the hot water supply secondary heat exchanger 210 and the piping on the inlet side of the hot water supply primary heat exchanger 110 (specifically, the upstream end of the hot water supply relay pipe 15). The second header 270A has a second header main body 271, a second header lid 272 that covers the opening of the second header main body 271, and a hot water supply outlet portion 273. The hot water supply outlet portion 273 is connected to the upstream side of the hot water supply relay pipe 15.

[0049] As shown in FIG. 7, the hot water supply secondary heat exchanger 210 is configured to include a plurality of second heat transfer pipes 211. The second heat transfer pipes 211 extend in a serpentine manner along a predetermined planar direction. The plurality of second heat transfer pipes 211 are stacked vertically and housed in the housing 230. The second heat transfer pipes 211 have one end and the other end that open in the same direction (rightward). One end (front side) of each second heat transfer pipe 211 is inserted into a first through hole 262 of the closing member 260A (see FIG. 10) and communicates with the hot water supply inlet 268. The other end (rear side) of each second heat transfer pipe 211 is inserted into a second through hole 263 of the closing member 260A (see FIG. 10) and communicates with the hot water supply outlet 273. In the hot water supply secondary heat exchanger 210, water is passed through the second heat transfer pipes 211 in parallel to perform heat exchange.

[0050] Similarly to the right side of the housing 230, the left side of the housing 230 is also provided with a closing member 260B, and a first header 265B and a second header 270B attached to the closing member 260B. The closing member 260B is a plate-shaped member that closes the left opening 248 of the fourth wall portion 244. The configuration of the closing member 260B is similar to that of the closing member 260A described above, and therefore a description thereof will be omitted.

[0051] The first header 265B is the part that connects the inlet of the bath secondary heat exchanger 220 to the downstream side of the return pipe 22. The first header 265B has a first header body 266, a first header cover 267, and a bath inlet section 269. The bath inlet section 269 is connected to the downstream side of the return pipe 22.

[0052] The second header 270B is the part that connects the outlet of the bath secondary heat exchanger 220 to the piping on the inlet side of the bath primary heat exchanger 120 (specifically, the upstream end of the bath relay pipe 40). The second header 270B has a second header main body 271, a second header cover 272, and a bath outlet section 274. The bath outlet section 274 is connected to the upstream side of the bath relay pipe 40.

[0053] As shown in FIG. 7, the bath secondary heat exchanger 220 is configured with multiple second heat transfer pipes 221, similar to the hot water supply secondary heat exchanger 210. The second heat transfer pipes 221 have one end and the other end that open in the same direction (left). One end (front side) of each second heat transfer pipe 221 is inserted into the first through hole 262 of the closing member 260B (see FIG. 10) and communicates with the bath inlet 269. The other end (rear side) of each second heat transfer pipe 221 is inserted into the second through hole 263 of the closing member 260B (see FIG. 10) and communicates with the bath outlet 274. In the bath secondary heat exchanger 220, water is passed through each second heat transfer pipe 221 in parallel to perform heat exchange.

[0054] [Burner device] The burner device 300 burns combustion gas to generate combustion exhaust. As shown in FIG. 3, the burner device 300 includes a burner case 330, a hot water supply burner group 310 (see FIG. 2), and a bath burner group 320 (see FIG. 2). The burner case 330 is provided below the can body 130 of the primary heat exchanger 100. The burner case 330 has a generally rectangular shape in plan view that is elongated in the left-right direction and is open at the top end. The burner case 330 has a square cylindrical shape similar to the can body 130. The interior of the burner case 330 is divided into left and right spaces by a partition 331. The partition 331 provided in the burner case 330 is connected to the lower end of the partition 131 of the primary heat exchanger 100. As a result, the left and right spaces within the burner case 330 are partitioned in a manner that they are connected to the left and right spaces within the can body 130 of the primary heat exchanger 100, respectively.

[0055] As shown in Figure 2, the hot water supply burner group 310 is arranged on the right side of the burner device 300 (the space on the right side separated by the partition 331 in the burner case 330), and the bath burner group 320 is arranged on the left side of the burner device 300 (the space on the left side separated by the partition 331 in the burner case 330). As a result, the hot water supply burner group 310 is arranged below the hot water supply primary heat exchanger 110 and supplies combustion exhaust to the hot water supply circuit 10. The bath burner group 320 is arranged below the bath primary heat exchanger 120 and supplies combustion exhaust to the bath circuit 20.

[0056] An ignition plug 311 and a flame rod 312 are arranged in the space above the hot water supply burner group 310. Similarly, an ignition plug 321 and a flame rod 322 are arranged above the bath burner group 320. Wiring (not shown) is connected to the rear ends of the ignition plugs 311, 321 and the flame rods 312, 322, respectively.

[0057] [Exhaust hood] As shown in Figure 3, the exhaust hood 400 is disposed between the primary heat exchanger 100 and the secondary heat exchanger 200. The exhaust hood 400 connects the upper end opening of the can body 130 of the primary heat exchanger 100 with the inlet 245 at the rear of the housing 230 of the secondary heat exchanger 200, forming a passage for the combustion exhaust. The interior of the exhaust hood 400 is divided into left and right sections by a partition 401. The partition 401 connects the upper end of the partition 131 of the primary heat exchanger 100 with the rear end of the partition 231 of the secondary heat exchanger 200, forming spaces corresponding to the hot water supply circuit 10 and the bath circuit 20, respectively.

[0058] As shown in FIG. 6, the exhaust hood 400 is configured to have an exhaust hood main body 410 and an exhaust hood rear portion 420.

[0059] The exhaust hood body 410 is formed to bulge upward in the front-to-rear direction, gradually increasing in height from the front end toward the rear. The rear end of the exhaust hood body 410 opens rearward, and a plate-shaped mounting portion 411 is provided around the periphery of this opening. The exhaust hood rear portion 420 is formed in the shape of a square dish that bulges rearward. The lower portion of the exhaust hood rear portion 420 is attached to the mounting portion 411 of the exhaust hood body 410 so as to close the rear opening of the exhaust hood body 410.

[0060] The exhaust hood rear part 420 has an insertion hole 421 at a position corresponding to the connected part 242A of the second wall part 242. The connecting member 242B is inserted into the insertion hole 421 and connected to the connected part 242A, thereby fixing the exhaust hood rear part 420 to the second wall part 242. As shown in FIG. 4 , an annular packing 422 is provided between the second wall part 242 and the exhaust hood rear part 420. The packing 422 prevents gas from passing between the second wall part 242 and the exhaust hood rear part 420.

[0061] [Exhaust stack] As shown in FIG. 1, exhaust pipe 500 is fixed to the front of housing 230 and is formed in a generally rectangular tubular shape that protrudes generally horizontally forward. This exhaust pipe 500 protrudes to the front of the outer box (not shown) through a through-hole provided in the front panel of an outer box that covers the outside of latent heat recovery water heater 2, and functions to discharge the combustion exhaust gas after latent heat is recovered in secondary heat exchanger 200 to the outside of latent heat recovery water heater 2. Also, as shown in FIG. 4, exhaust pipe 500 is provided at the front of exhaust pipe 500 with exhaust outlet 501. Exhaust outlet 501 is formed in a generally elliptical shape that is long in the left-right direction when viewed from the front. A flange portion 502 that protrudes outward in a flange-like shape is provided at the rear end of exhaust pipe 500. Flange portion 502 is formed in a generally rectangular ring shape that is long in the left-right direction when viewed from the front.

[0062] The flange portion 502 has an insertion hole 503 at a position corresponding to the connected portion 241A of the first wall portion 241. The connecting member 241B is inserted into the insertion hole 503 and connected to the connected portion 241A, thereby fixing the flange portion 502 to the first wall portion 241. As a result, the exhaust tube 500 is fixed to the front side with respect to the front portion of the housing 230, and the exhaust outlet 501 of the exhaust tube 500 is disposed in front of the outlet 246 of the housing 230. Therefore, the exhaust tube 500 can discharge the combustion exhaust gas received from the outlet 246 of the housing 230 to the outside through the exhaust outlet 501. An annular packing 504 is provided between the first wall portion 241 and the flange portion 502. The packing 504 prevents gas from passing between the first wall portion 241 and the flange portion 502.

[0063] [Latent heat recovery water heater manufacturing method] The configuration of the latent heat recovery water heater 2 of this embodiment has been described above, and next, a method for manufacturing the latent heat recovery water heater 2 will be described. The method for manufacturing the latent heat recovery water heater 2 of this embodiment includes the process of manufacturing the secondary heat exchanger 200, which will be described below. The processes for manufacturing the components other than the secondary heat exchanger 200 (primary heat exchanger 100, burner device 300, exhaust hood 400, exhaust stack 500, etc.) and the process of assembling these components with the secondary heat exchanger 200 are not particularly limited.

[0064] [Secondary heat exchanger manufacturing method] The method of manufacturing the secondary heat exchanger 200 includes the steps of forming the box body 291, constructing the housing 230 using the box body 291, and inserting the second heat transfer pipes 211, 221 into the housing 230. As shown in Fig. 14, the box body 291 is open at the top and has a box shape that is long in the left-right direction. An inlet 245 is provided in the rear wall (second wall 242) of the box body 291, and an outlet 246 is provided in the front wall (first wall 241) of the box body 291. Connected portions 241A and 242A are formed in the first wall 241 and the second wall 242. The box body 291 is formed by drawing a metal plate or the like. The box body 291 is also used as an exhaust casing 290 of the sensible heat recovery water heater 3 described later. A lid 233 that covers the box body 291 from above is also formed by drawing a metal plate or the like.

[0065] A right opening 247 and a left opening 248 are provided in the right and left wall portions of the box body 291, thereby forming a main body 232, which is a part of the housing 230 (see FIG. 9). The right opening 247 and the left opening 248 are formed by, for example, punching or cutting. Connected portions 243A and 244A are formed around the right opening 247 and the left opening 248. A drain outlet 251 is provided in the bottom wall of the box body 291.

[0066] Plate-shaped closing members 260A and 260B are formed by processing a metal plate. A plurality of first through holes 262, a plurality of second through holes 263, and a plurality of insertion holes 264 are formed in closing members 260A and 260B. The first through holes 262, the second through holes 263, and the insertion holes 264 are formed by, for example, punching or cutting.

[0067] The metal plate is processed to form partitions 231 that separate the interior of the housing 230. The partitions 231 are formed by, for example, bending. The partitions 231 are disposed inside the main body 232.

[0068] 10, a plurality of second heat transfer tubes 211 are fixed to the closing member 260A. In this embodiment, the front end of each of the second heat transfer tubes 211 is inserted into the first through hole 262, and the rear end of each of the second heat transfer tubes 211 is inserted into the second through hole 263, and in this state, each of the second heat transfer tubes 211 is fixed to the closing member 260A by, for example, welding or brazing. In this way, a first assembly 281 is produced in which the plurality of second heat transfer tubes 211 and the closing member 260A are integrally assembled.

[0069] Furthermore, a first header 265A is fixed by welding or brazing to the end of the second heat transfer tube 211 inserted into the first through hole 262 of the closing member 260A (see FIGS. 7 and 8). A second header 270A is fixed by welding or brazing to the end of the second heat transfer tube 211 inserted into the second through hole 263 of the closing member 260A (see FIGS. 7 and 8).

[0070] The blocking member 260B and the plurality of second heat transfer tubes 221 are assembled in the same manner as above to produce the second assembly 282. The first header 265B and the second header 270B are also fixed to the second assembly 282 in the same manner.

[0071] A first assembly 281 in which the plurality of second heat transfer tubes 211 and the closing member 260A are integrally assembled is inserted into the main body 232 (housing 230) from the right opening 247. The plurality of second heat transfer tubes 211 are disposed in the main body 232, and the right opening 247 is closed by the closing member 260A. The closing member 260A is fixed to the third wall 243 by connecting the connecting member 243B inserted into the insertion hole 264 of the closing member 260A to the connected portion 243A.

[0072] The second assembly 282, in which the plurality of second heat transfer tubes 221 and the closing member 260B are integrally assembled, is inserted into the main body 232 (housing 230) from the left opening 248. The plurality of second heat transfer tubes 221 are disposed in the main body 232, and the left opening 248 is closed by the closing member 260B. The closing member 260B is fixed to the fourth wall 244 by connecting a connecting member (not shown) inserted into the insertion hole 264 of the closing member 260B to the connected portion 244A.

[0073] A step is then performed in which the upper opening 235 of the main body 232, to which the first assembly 281 and the second assembly 282 are attached, is closed with the lid 233. By performing these steps, the secondary heat exchanger 200 is completed (see FIG. 8).

[0074] [Assembly of the secondary heat exchanger with the exhaust hood and exhaust stack] Secondary heat exchanger 200 is connected to exhaust hood 400 at its rear surface and to exhaust stack 500 at its front surface (see FIG. 4). In detail, connecting member 242B inserted into insertion hole 421 of exhaust hood 400 is fixed to connected portion 242A of second wall portion 242 of housing 230 via packing 422. Also, connecting member 241B inserted into insertion hole 503 of exhaust stack 500 is fixed to connected portion 241A of first wall portion 241 of housing 230 via packing 504.

[0075] [Sensible heat recovery water heater] Next, a sensible heat recovery water heater 3 according to an embodiment will be described with reference to Figures 11 to 14. The sensible heat recovery water heater 3 is equipped with a primary heat exchanger 100, a burner device 300, an exhaust hood 400, and an exhaust pipe 500, which are the same as those of the latent heat recovery water heater 2. In the following description of the configuration of the sensible heat recovery water heater 3, a description of the same configuration as the latent heat recovery water heater 2 will be omitted. The sensible heat recovery water heater 3 is equipped with an exhaust casing 290 instead of the secondary heat exchanger 200.

[0076] As shown in Figure 11, sensible heat recovery water heater 3 is not provided with secondary heat exchanger 200, so water introduced into sensible heat recovery water heater 3 is introduced directly into primary heat exchanger 100 without passing through secondary heat exchanger 200. That is, water inlet pipe 12 is connected to hot water supply inlet opening 114 (see Figure 5), and return pipe 22 is connected to bath inlet opening 124 (see Figure 5). In detail, as shown in Figure 12, hot water supply circuit 10 of sensible heat recovery water heater 3 flows water from water inlet 11 into water inlet pipe 12, passes water through hot water primary heat exchanger 110, and heats the water by exchanging heat with the combustion exhaust gas from hot water supply burner group 310, and then flows through hot water outlet pipe 13 and discharges hot water from hot water outlet 14. In addition, the bath circuit 20 of the sensible heat recovery water heater 3 uses a circulation pump P to draw hot water from the bathtub B into a return pipe 22 from a hot water inlet 21 connected to an opening in the bathtub B, and while passing the water through the bath primary heat exchanger 120, reheats the hot water by heat exchange with the combustion exhaust from the bath burner group 320, and then discharges the hot water, which has become hotter, into the bathtub B from a hot water outlet 24 via a supply pipe 23.

[0077] In the sensible heat recovery water heater 3, the latent heat of the combustion exhaust is not recovered, and therefore no drain is generated. For this reason, the sensible heat recovery water heater 3 does not have the drain hose 31, drain outlet 251, neutralizer 32, etc. that the latent heat recovery water heater 2 has (see FIG. 2).

[0078] [Exhaust casing] 14, exhaust casing 290 is box-shaped and includes box body 291, packing 234, and lid 233. That is, exhaust casing 290 of sensible heat recovery water heater 3 is made up of the same materials as those used to form housing 230 of secondary heat exchanger 200 of latent heat recovery water heater 2. Therefore, it is not necessary to provide a separate mold for manufacturing exhaust casing 290.

[0079] As shown in Fig. 13, exhaust casing 290 is disposed at the position of casing 230 of secondary heat exchanger 200 in latent heat recovery water heater 2 (see Fig. 4). That is, exhaust casing 290 is attached to exhaust hood 400 and exhaust stack 500, similar to casing 230 of secondary heat exchanger 200. Exhaust casing 290 is configured to take in combustion exhaust air from exhaust hood 400 through inlet 245 and discharge the combustion exhaust air from outlet 246 to exhaust stack 500. Similar to casing 230, a partition 231 is provided inside exhaust casing 290.

[0080] [Effects of the embodiment] As described above, in this embodiment, exhaust casing 290 of sensible heat recovery water heater 3 and casing 230 of secondary heat exchanger 200 of latent heat recovery water heater 2 are configured from a common box body 291. In other words, the manufacturing method for water heater 1 of this embodiment includes a step of forming box body 291 and a step of using this box body 291 to configure casing 230 of secondary heat exchanger 200 of latent heat recovery water heater 2 or exhaust casing 290 of sensible heat recovery water heater 3. This eliminates the need to separately manufacture a mold for exhaust casing 290 of sensible heat recovery water heater 3, making it possible to reduce manufacturing costs even when the manufacturing lot size of sensible heat recovery water heater 3 is small.

[0081] Furthermore, when the exhaust casing 290 is designed individually, it is necessary to verify the fitment of the exhaust casing 290 to the exhaust hood 400 and the exhaust stack 500. However, in this embodiment, the exhaust casing 290 and the housing 230 of the secondary heat exchanger 200 are constructed from the same box body 291, so the process of verifying the fitment of the exhaust casing 290 or the housing 230 of the secondary heat exchanger 200 to the exhaust hood 400 and the exhaust stack 500 can be minimized. Furthermore, since the common exhaust pipe 500 is fixed in the same manner to each of the exhaust casing 290 and the housing 230, which are made up of a common box body 291, the work required to verify the fitment of the exhaust pipe 500 to the through hole in the front panel can be minimized.

[0082] When assembling the exhaust casing 290 or the housing 230 of the secondary heat exchanger 200 with the exhaust hood 400 and the exhaust stack 500, packings 422, 504 are arranged between the rims of the inlet 245 and outlet 246 of the exhaust casing 290 or the housing 230 of the secondary heat exchanger 200 and the exhaust hood 400 and the exhaust stack 500. Since the exhaust casing 290 and the housing 230 of the secondary heat exchanger 200 of this embodiment are configured from a common box-shaped body 291 having the inlet 245 and outlet 246, the packings 422, 504 can also be common between the exhaust casing 290 and the housing 230 of the secondary heat exchanger 200.

[0083] <Other embodiments> The present disclosure is not limited to the embodiments described above and in the drawings. For example, any combination of features of the above-described or following embodiments is possible within a range that does not contradict. Furthermore, any feature of the above-described or following embodiments may be omitted unless explicitly stated as essential. Furthermore, the above-described embodiment may be modified as follows.

[0084] In the embodiment, a water heater 1 is exemplified in which the secondary heat exchanger 200 is divided into a hot water secondary heat exchanger 210 and a bath secondary heat exchanger 220, but the water heater of the present disclosure may also be a water heater in which the secondary heat exchanger is composed only of a hot water secondary heat exchanger. [Explanation of symbols]

[0085] 1...Water heater, 2...Latent heat recovery water heater, 3...Sensible heat recovery water heater 10...Hot water supply circuit, 11...Water inlet, 12...Water inlet pipe, 13...Hot water outlet pipe, 14...Hot water outlet, 15...Hot water supply relay pipe, 20...Bath circuit, 21...Hot water inlet, 22...Return pipe, 23...Supply pipe, 24...Hot water outlet, 31...Drain hose, 32...Neutralizer, 33...Controller, 40...Bath relay pipe 100... Primary heat exchanger, 110... Primary heat exchanger for hot water supply, 111... First heat transfer pipe, 112... Connecting pipe, 114... Hot water supply inlet opening, 115... Hot water supply outlet opening, 120... Primary heat exchanger for bath, 121... First heat transfer pipe, 122... Connecting pipe, 124... Bath inlet opening, 125... Bath outlet opening, 130... Boiler body, 131... Partition section 200... Secondary heat exchanger, 210... Secondary heat exchanger for hot water supply, 211... Second heat transfer tube, 220... Secondary heat exchanger for bath, 221... Second heat transfer tube 230... Housing, 231... Partition, 232... Main body, 233... Lid, 234... Packing, 235... Upper opening, 240... Bottom wall, 241... First wall, 241A... Connected part, 241B... Connecting member, 242... Second wall, 242A... Connected part, 242 B...Connecting member, 243...Third wall, 243A...Connected part, 243B...Connecting member, 244...Fourth wall, 244A...Connected part, 245...Inlet (an example of an inlet), 246...Outlet (an example of an outlet), 247...Right side opening, 248...Left side opening, 24 9...extension portion, 250...groove portion, 251...drain discharge port, 260A, 260B...blocking member, 261...plate-shaped portion, 262...first through hole, 263...second through hole, 264...insertion hole, 265A, 265B...first header, 266...first header body, 267...first header cover body, 268...hot water supply inlet portion, 269...bath inlet portion, 270A, 270B...second header, 271...second header body, 272...second header cover body, 273...hot water supply outlet portion, 274...bath outlet portion, 281...first assembly, 282...second assembly body 290...exhaust casing, 291...box body 300... burner device (an example of a combustion device), 310... hot water supply burner group, 311, 321... spark plugs, 312, 322... flame rods, 320... bath burner group, 330... burner case, 331... partition section 400...exhaust hood, 401...partition portion, 410...exhaust hood body, 411...mounting portion, 420...exhaust hood rear portion, 421...insertion hole, 422...packing 500...exhaust pipe, 501...exhaust outlet, 502...flange portion, 503...through hole, 504...packing B: Bathtub, P: Circulation pump

Claims

[Claim 1] A method for manufacturing a water heater including a combustion device and a primary heat exchanger fixed to an upper portion of the combustion device and recovering sensible heat from combustion exhaust gas generated in the combustion device, The water heater includes a latent heat recovery water heater further including a secondary heat exchanger that recovers latent heat from the combustion exhaust gas discharged from the primary heat exchanger, and a sensible heat recovery water heater further including an exhaust casing that discharges the combustion exhaust gas discharged from the primary heat exchanger to the outside, The method for manufacturing the water heater includes a step of forming a box having an inlet portion at a rear side for receiving combustion exhaust gas and an outlet portion at a front side for discharging the combustion exhaust gas, When the water heater is a latent heat recovery type water heater, the method further includes the steps of: forming openings on both sides of the box body to form a housing for the secondary heat exchanger; and inserting a plurality of heat transfer tubes into the housing through the openings. When the water heater is a sensible heat recovery water heater, the method for manufacturing a water heater further includes a step of constructing the exhaust casing using the box body.

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