Water Heater

Abstract

In a water heater provided with an inlet pipe a downstream end of which is connected with an upstream end of a water heating channel of a heat exchanger for producing hot water, an outlet pipe an upstream end of which is connected with a downstream end of the water heating channel, and a bypass pipe branching at a part of the inlet pipe, which is positioned at an upstream-end part away from an upstream end, and is connected with a part of the outlet pipe, which is positioned at a more downstream part than at an upstream end, a connecting part of the bypass pipe with the outlet pipe and another connecting part of an inlet pipe and the upstream end of the water heating channel are arranged at a same height in a setting state of the water heater.

Claims

1. A water heater provided with a heat exchanger which has a water heating channel structured by successively connecting each of a plurality of heat absorbing pipes aligned in parallel and produces hot water by heating water while flowing water in the water heating channel, and a heat resource for heating the heat exchanger, comprising, an inlet pipe upwardly extending to the heat exchanger for introducing the water into the water heating channel, a downstream end of which is connected with an upstream end of the water heating channel of the heat exchanger; an outlet pipe, an upstream end of which is connected with a downstream end of the water heating channel of the heat exchanger, the outlet pipe extending away from the heat exchanger for downwardly flowing the hot water out of the water heating channel; a bypass pipe branching at a part of the inlet pipe, which is positioned at a more upstream part than at the downstream end, the bypass pipe being connected with a part of the outlet pipe, which is positioned at a more downstream part than at the upstream end, and the bypass pipe mixing the water in the outlet pipe, wherein, as a premise that one of horizontal planes is a standard for defining height, a connecting part of the bypass pipe with the outlet pipe and a connecting part of the inlet pipe with the upstream end of the water heating channel are arranged at a same height in a setting state of the water heater.

2. The water heater as claimed in claim 1, wherein all of the heat absorbing pipes structuring the water heating channel of the water heater are arranged at a same height and in a single horizontal plane.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 is a perspective view of an embodiment of a water heater of the invention.

[0017] FIG. 2 shows main parts of the water heater shown in FIG. 1.

[0018] FIG. 3 is a partially sectional view in an A-A direction in FIG. 2.

[0019] FIG. 4 is a partially sectional view in a B-B direction in FIG. 3.

DESCRIPTION OF EMBODIMENTS

[0020] A water heater 1 as an embodiment is now explained with reference to drawings. Wordings which intend “upward” and “downward” in following explanations correspond to positional relationships in a setting state of the water heater 1.

[0021] Referring to FIG. 1, the water heater is set on an exterior wall of the like of a building such as a house by fastening with a bolt or the like. For this purpose, in a case 2 provide with the water heater 1, not only a lower fixing piece 3 protruded downward from a lower end of a rear face 2a opposite to the exterior wall of the building is provided but also an upper fixing piece, which is not shown and a function of which is similar to the lower piece 3, protrudes upward from an upper end of the rear face 2a. Further, in the case 2, each of a downstream end part 4a of an outlet pipe, which is described below, extending downward in the case 2 and suspending from a bottom face 2b, an upstream end part 5a of an inlet pipe, which is described below, crossing perpendicularly with the bottom face 2b and entering the case 2, and an upper end part 6 of a fuel-gas supply pipe protrude downwardly. A hot-water supply pipe leading to an outflow faucet is connected with the downstream end part 4a of the outlet pipe and a water supply pipe connected with a water pipe is connected with the upper end part 5a of the inlet pipe.

[0022] Furthermore, a supply and exhaust tube T which extend upwardly and has a cylindrical shape is provided at a top end of the case. In the supply and exhaust tube T, an air supply tube and an exhaust tube are independent of each other in such a manner as being arranged inward and outward in a radial direction. The supply and exhaust tube T sucks an outside air in the case 2 by a rotation of a fan which is described below. The air sucked in the case 2 is mixed with a fuel gas supplied through the above-identified fuel-gas supply pipe in a combustion casing, which is described below, and becomes a gas mixture. Additionally, the supply and exhaust tube T exhausts a combustion gas generated by combustion of the gas mixture in the above-identified combustion housing.

[0023] Referring to FIG. 2, a bypass pipe 7 branches from the inner pipe 5 at a more downstream part positioned away from the upstream end part 5a of the inlet pipe 5, as shown in FIG. 1, and at a more upstream part positioned than at a downstream end 5b. Main parts MP of the water heater 1 is housed in the case 2 shown in FIG. 1. The main parts MP is provided with the combustion housing 8, a heat exchanger 9 mounted on an upper end part of the combustion housing 8, the fan 10 arranged under the combustion housing 8. Further, the main parts are provided with the inlet pipe 5 upwardly extending to the heat exchanger 9 in the case 2 shown in FIG. 1, the outlet pipe 4 downwardly extending away from the heat exchanger 9 in the case 2, and the bypass pipe 7 branching from the inlet pipe 5 in the case 2, as above-mentioned, and connected with a more downstream part of the outlet pipe 4.

[0024] In the combustion housing 8 and the heat exchanger 9, opposite parts to the rear face 2a of the case 2 shown in FIG. 1 are named rear faces 8a, 9a. Although depictions in FIG. 2 are simplified, the water supply pipe WSP connected with the water pipe is connected with the upstream end part 5a of the inlet pipe 5 shown in FIG. 1. Accordingly, the bypass pipe 7 is positioned at the more upstream part than at the branching part from the inlet pipe 5 and is connected with the water supply pipe WSP through a midst part of the inlet pipe 5 leading to the upstream end part 5a. The hot-water supply pipe HSP leading to the outlet faucet is connected with the downstream end part 4a of the outlet pipe 4.

[0025] Additionally, referring to FIG. 3, the inlet 5 upwardly extends around the fan 10 and from the upstream end part 5a downwardly positioned away from the heat exchanger 9, and the downstream end 5b is connected with an upstream end 11a of the water heating channel 11, which protrudes from the rear face 9a of the heat exchanger 9.

[0026] An upstream end 4b of the outlet pipe 4 is connected with a downstream end 11b of the water heating channel 11. The downstream end 11b of the water heating channel 11 is arranged at an outside of a side face 9c of the heat exchanger 9. The outlet pipe 4 extends parallel to the side face 9c of the heat exchanger 9 from the downstream end 11b of the water heating channel 11 and linearly in a perpendicular direction of both of the rear face 9a and front face 9b opposite to the rear face 9a of the heat exchanger 9. A midst part of the outlet pipe 4 leading to the rear face 9a is downwardly bent. The downstream end 7a of the bypass pipe 7 branching from the inlet pipe 5 at the above-mentioned part pf the inlet pipe 5 is connected with a lower part of a linear part 4c of the outlet pipe 4 by downwardly bending from the upstream end 4b. In the embodiment, though the upstream end 4b of the outlet pipe 4 is connected with the downstream end 11b of the water heating channel 11 and the downstream end 7a of the bypass pipe 7 is connected with the lower part of the linear part 4c of the outlet pipe 4, it is possible that the downstream end 11b of the water heating channel is regarded as a part of the outlet pipe 4. Further, it is possible that the downstream end 11b of the water heating channel 11 is regarded as an end positioned at the most downstream part of the heat exchanger 9 and a protruding part from the front face 9b of the heat exchanger 9. At any of the above-mentioned cases, the downstream end 7a of the bypass pipe 7 is connected with a lower part of the outlet pipe 4 which is connected with a downstream end such as the downstream end 11b of the water heating channel 11.

[0027] A plurality of fins 12 are provided in a hollow part from the front face 9b to the rear face 9a of the heat exchanger 9 and each of fins 12 is arranged parallel to the front face 9b and rear face 9a. The water heating channel 11 is formed by a first heat absorbing pipe 13 having an upstream end, which forms the upstream end 11a and a main part of which has a straight-shape, four second heat absorbing pipes 14, each of which is U-shaped and a straight part 14a of each of which is arranged parallel to the first absorbing pipe 13, a U-shaped first bent pipe 15 connecting a downstream end of the first absorbing pipe 13 with an upstream end of a straight part 14a of the second absorbing pipe 14 which is adjacent to the first heat absorbing pipe 13, three second bent pipes 16 connecting each of downstream ends with each of upstream ends of straight parts 14a of the two adjacent second heat absorbing pipes 14, which are similar to the first bent pipe 15, and a third bent pipe 17 connected with a downstream end the straight part 14a of the second heat absorbing pipe 14 positioned at the most downstream part, a downstream end of which forms the downstream end 11d of the water heating channel 11 and which is similar to the first and second bet pipes 15, 16. Not only the first heat absorbing pipe 13 and each of the second heat absorbing pipes 14 are successively connected through the first and second bent pipes 15, 16 but also the third bent pipe 17 is successively connected with the second heat absorbing pipe 14 positioned at the most downstream part of the water heating channel 11. Accordingly, the water heating channel 11 meanders from the upstream end 11a to the downstream end 11b. The downstream end 11b of the water heating channel 11 may be the downstream end of the straight part 14a of the second heat absorbing pipe 14, which is positioned in the most downstream part in the heat exchanger 9 and the downstream end connected with the upstream end of the third bent pipe 17. In this case, the outlet pipe 4 can be regarded as the one containing a pipe leading from the third bent pipe 17 to the linear part 4c.

[0028] The downstream end of the first heat absorbing pipe 13, the upstream and downstream ends of the straight parts of the second heat absorbing pipes 14 protrude outward so as to come near the front face 9b of the heat exchanger 9. Accordingly, the first bent pipe 15, the second bent pipes 14 and the third bent pipe 17 also protrude outward so as to come near the front face 9b of the heat exchanger 9. On the other hand, as is similar to the upstream end of the first heat absorbing pipe 13, the U-shaped part of each of the second heat absorbing pipes 14 protrudes outward so as to come near the rear dace 9a of the heat exchanger 9. The heat absorbing pipe 13 and each of the second heat absorbing pipes 14 as well as each of the fins 12 may be made of a metal with a high thermal conductivity such as copper.

[0029] As shown in FIG. 3, the first heat absorbing pipes 13 and the straight parts 14a of the second heat absorbing pipes 14 not only are arranged in parallel with a prescribed distance from the side face 9c to the other side face 9d positioned at the most upstream part, which is opposite to the side face 9c, but also pierce each of the fins 12 in a perpendicular direction. Further, all of the first heat absorbing pipe 13 and each of the straight parts 14a of the second heat absorbing pipes 14 are arranged at a same height in the water heater 1 shown in FIG. 1. The “height” referred here is defined by a perpendicular distance from a horizontal plane, which is a standard, such as the bottom face 2b of the case 2 of the water heater 1 in a setting state. In other words, each of center lines 13c, 14c of all of the first heat absorbing pipe 13 and the straight part 14a of each of the heat absorbing pipes 14 are arranged in a same horizontal plane HP. Additionally, the U-shaped part 14b of each of the second heat absorbing pipes 14, the first bent pipe 15, the second bent pipes 16 and the third bent pipe 17 as well as the first heat absorbing pipe 13 and the straight part 14a of each of the second heat absorbing pipes 14 are arranged at a same height.

[0030] In the combustion housing 8 in which the above-mentioned heat exchanger 9 is mounted on the top end part, a burner 18 is provided with a lower part from the side face 8b of the combustion housing 8 to the side face 8c arranged at a lower part of the side face 9c of the heat exchanger 9, which is opposite to the side face 8b. The burner 18 is provided with nineteen unit-burners 18a each of which is arranged at a prescribed clearance. In the burner 18, each of the unit-burner 18a is arranged from a side of the rear face 8a to a side of a front face opposite to the rear face 8a.

[0031] As is similar to the conventional water heater, a fuel gas supplied from the above-mentioned fuel gas supply pipe entering the case 2 and through a gas manifold, which is not shown, via a fuel gas pipe connected with the upstream end part 6 of the fuel gas supply pipe is mixed with a first air, which is a part of an outside air surrounding the case 2, sucked from the above-mentioned air supply tube of the air supply and exhaust tube T shown in FIG. 1 by an operation of the fun 10 and a gas mixture of the fuel gas and the first air is supplied in the unit-burners 18a. A remaining outside air sucked from the above-mentioned air supply tube through the clearances is supplied at burner ports positioned at a top end of the unit-burners 18a. Each of the unit-burners 18a is ignited by a spark generated from an ignition electrode accompanied by an operation of an igniter and therefore the burner 18 is ignited. After the ignition of the burner 18, a combustion gas generated by combustion of the fuel gas moves to the heat exchanger 9 from a combustion chamber 8d over the burner 18, passes between each of the fins 12, and is exhausted from the above-mentioned air exhaust tube of the air supply and exhaust tube T shown in FIG. 1. When the combustion gas passes between each of the fins 12 of the heat exchanger 9, sensible heat is absorbed in each of the fins 12 and is transmitted to the first heat absorbing pipe 13 and the straight part 14a of each of the second heat absorbing pipes 14. At a same time of the ignition of the burner 18, the water is suppled at the upstream end 11a of the water heating channel 11 of the heat exchanger 9 from the downstream end 5b shown in FIG. 2. The water flowing in the water heating channel 11 is heated by the transmitted heat to the first heat absorbing pipe 13 and the straight part 14a of each of the second heat absorbing pipes 14 and becomes the hot water. The hot water flows out the outlet pipe 4 from the downstream end 11b and through the upstream end 4b of the water heating channel 11.

[0032] Since the above-mentioned igniter and the ignition electrode are provided with the conventional water heater, these are omitted in the figures. The ignition of the burner 18, inflow of the water in the water heating channel 11 through the inlet pipe 5, and outflow of the hot water from the water heating channel 11 to the outlet pipe 4 begin by an opening operation of the outflow faucet by a user. Similarly, the outflow of the hot water from the outflow faucet is stopped, the water flow in the water heating channel 11 is stopped, and the burner 18 is put out. Such an automatic operation of the water heater 1 as above-mentioned is similar to that of the conventional water heater. Accordingly, valve units for supplying the water and flowing out the hot water, valve units for supplying and stopping the fuel gas, and a controller or the like for controlling movement of the above-mentioned igniter and each of the above-mentioned valves are omitted in the figures.

[0033] As shown in FIG. 2, in the water heater 1, a connecting part CP.sub.1 of the bypass pipe 7 with the outlet pipe 4 is arranged at a same height of a connecting part CP.sub.2 of the inlet pipe 5 with the upstream end 11a of the water heating channel 11. Specifically, the connecting part CP.sub.1 is a part where the downstream end 7a of the bypass pipe 7 is connected with the linear part 4c of the outlet pipe 4 and the connecting part CP.sub.2 is a part where the upstream end 11a of the water heating channel 11 is connected with the downstream end 5b of the inlet pipe 5. The wordings, “same height” is defined by a standard which is such a horizontal plane as the bottom face 2b of the case 2 shown in FIG. 1 in the setting state of the state or the like. Further, in other words, a state where the connecting parts CP.sub.1, CP.sub.2 are positioned at a same height means that a state where an intersection point IP of a center line 4c.sub.1 of the linear part 4c of the outlet pipe 4 with a center line 7a.sub.1 of the downstream end 7a of the bypass pipe 7, and the center line 13a of the first heat absorbing pipe 13 structuring a part of the water heating channel 11 exist in a horizontal plane HP shown in FIG. 4.

[0034] In general, a water temperature at the upstream end 11a of the water heating channel 11 is about from 5° C. to 25° C. and a hot-water temperature at the downstream end 11b is about from 50° C. to 70° C. As a temperature of the water rises beyond 4° C., a specific gravity of the water decreases. Accordingly, a weight of the hot water at the downstream end 11b of the water heating channel 11 is lighter than that of the water at the upstream end 11a of the water heating channel 11. However, as above-mentioned, the connecting part CP.sub.1 of the bypass pipe 7 with the outlet pipe 4 and the connecting part CP.sub.2 of the inlet pipe 5 with the upstream end 11a of the water heating channel 11 are positioned at the same height and therefore, even though there is difference in the specific gravity between the water and the hot water, either the remaining hot water in the outlet pipe 4 does not upwardly flow in the outlet pipe 4 or the remaining water in a part near the upstream end 11a of the water heating channel 11, in the inlet pipe 5 and in the bypass pipe 7 does not flow in the outlet pipe 4. Accordingly, if a passing time from stoppage of outflow to resumption of outflow is prolonged, it is possible that outflow of fluid mixture at a lower temperature than at a preset temperature from the outflow faucet is suppressed.

[0035] As shown in FIGS. 3 and 4, in the water heater 1, the first heat absorbing pipe 13, the second heat absorbing pipes 14, the first bent pipe 15, the second bent pipes 16, and the third bent pipe 17 forming the water heating channel 11 of the heat exchanger 9 are arranged at the same height and in a single horizontal plane. As compared with a heat exchanger provided with a plurality of the water heating channels 11 formed by such heat absorbing pipes or the like as the above-mentioned, each of the water heating channels 11 of which is arranged in a perpendicular direction, i.e., arranged in a different horizontal plane, and is successively connected, in the case where a water temperature at the upstream end 11a of the water heating channel 11 positioned in the lowest horizontal plane is as low as that of the water heating channel 11 arranged in a single horizontal plane and a hot-water temperature at the downstream end 11b of the water heating channel 11 arranged in the highest horizontal plane is as high as that of the water heating channel 11 arranged in a single horizontal plane, a temperature change amount of the water heating channel 11 of the heat exchanger 9 is larger than that of each of the water heating channels 11 provide with the heat exchanger and arranged in the different horizontal planes. The above-mentioned explanation is now specifically described as follows: A heat exchanger provided with two water heating channels 11 is exemplified. One of the water heating channels 11 is arranged in one horizontal plane and the other in the other horizontal plane. The former names an upper water heating channel 11 and the latter a lower water heating channel 11. The upper water heating channel 11 is successively connected with the lower water heating channel 11, the upstream end 11a is provided with the lower water heating channel 11, and the downstream end 11b is provided with the upper water heating channel 11. In this heat exchanger, since relatively hot water after being heated in the lower water heating channel 11 flows in the upper water heating channel 11, the hot water with relatively small heat conductivity remains in the upper water heating channel and therefore the temperature change amount per one water heating channels is smaller. On the contrary, in the heat exchanger 9 in which the water heating channel 11 is arranged in the single horizontal plane, since all of the heat absorbing pipes are arranged at the same height, the hot water and the water remain in one water heating channel 11 and therefore the heat temperature change amount is larger. Further, in order to absorb same amount of heat, it is necessary for the heat changer 9 with one water heating channel 11 that a length of the water heating channel 11 is longer and amount of the remaining hot water and water in the water heating channel 11 is more as compared with the heat exchanger provided with two water heating channels 11. Accordingly, suppressing movement of the hot water and the water is harder after the stoppage of outflow and the outlet pipe 4 has a length to some extent so that the hot water upwardly flows and backflows in the water heating channel 11, resulting in easily taking place the reverse flow of the hot water. However, the suppress of the reverse hot-water flow becomes excellent by the heat exchanger 9 aligned the water heating channel 11 in the single horizontal plane because, as above-mentioned, the connecting part CP.sub.1 of the bypass pipe 7 with the outlet pipe 4 and the connecting part CP.sub.2 of the inlet pipe 5 with the upstream end 11a of the water heating channel 11 are arranged at the same height.

[0036] Though the invention is described base on the above-mentioned embodiment, the invention is not limited to the above-mentioned embodiment. The shape and the number or the like of the heat absorbing pipe structuring the water heating channel 11 is not specifically limited, for example. Further, the shape or the like of the inlet pipe 5, the outlet pipe 4 and the bypass pipe 7 is not specifically limited. Furthermore, the structure of the valve units except the main parts MP, the controller, the burner 18 or the like are not specifically limited. In addition, a plurality of the water heating channels 11 each of which is arrange at a different height in the heat exchanger 9 so long as the connecting part CP.sub.1 of the bypass pipe 7 with the outlet pipe 4 and the connecting part CP2 of the inlet pipe 5 with the upper end 11a of the water heating channel 11 are arranged at the same height. In this case, each of the water heating channels 11 can be arranged at the different height by interposing a member, such as a header, which branches in a perpendicular direction both near the downstream end 5b of the inlet pipe 5 and near the upstream end 4b of the outlet pipe 4, and each of the water heating channels 11 is connected with each of branched water channels provided with the above-mentioned member and arranged in a perpendicular direction. In other words, each of the water heating channels 11 arranged in a different horizontal plane at a constant distance is connected both with the inlet pipe 5 and with the outlet pipe 4. Further, in the above-mentioned case, the connecting part CP.sub.1 of the bypass pipe 5 with the outlet pipe 4 is arranged at a more upstream part of the above-mentioned member and the connecting part CP.sub.2 of the inlet pipe 5 with the upstream end 11a of each of the water heating channels 11 is arranged at a more downstream part of the above-mentioned member.

[0037] It is possible that the invention is also adapted to a water heater with which the heat exchanger 9 and a heat exchanger for heating a room or the like are provided.

EXPLANATION OF SYMBOLS

[0038] 1 Water heater

[0039] 4 Outlet pipe

[0040] 4b Upstream end of outlet pipe 4

[0041] 5 Inlet pipe

[0042] 5b Downstream end of inlet pipe 5

[0043] 7 Bypass pipe

[0044] 9 Heat exchanger

[0045] 11 Water heating channel

[0046] 11a Upstream end of water heating channel

[0047] 13 Heat absorbing pipe, i.e., first heat absorbing pipe

[0048] 14 Heat absorbing pipe, i.e., second heat absorbing pipe

[0049] 18 Heat resource, i.e., burner

[0050] CP.sub.1 Connecting part pf bypass pipe 7 with outlet pipe 4

[0051] CP.sub.2 Connecting part of inlet pipe 5 with upstream end 11a of water heating channel 11