JP2020085278A - Water heater - Google Patents

Abstract

To enable a bypass pipe to be laid out without interfering with other components even in a narrow space in a housing.SOLUTION: A water heater 1 comprises: a heat exchanger 5 having a meandering heat transfer tube 11 in which a plurality of U-shaped tubes 12 penetrates in a right-left direction inside a casing 10 and is respectively exposed on the left and right side surfaces of the casing 10, at right and left ends; a burner that is installed below the heat exchanger 5, and passes combustion exhaust gas into the casing 10; a water supply tube 18 connected to the inlet side end part of the heat transfer tube 11 on the left side surface of the casing 10; and a hot water tapping tube 19 connected to the outlet end part of the heat transfer tube 11 on the right side surface of the casing 10. The water heater includes a partial bypass tube 24 that partially bypasses the heat exchanger 5 by connecting the U-shaped tube 12A exposed on the right side surface and the hot water tapping tube 19.SELECTED DRAWING: Figure 1

Description

The present invention relates to a water heater that heats water by using a heat exchanger having a meandering heat transfer tube that penetrates a casing in the left-right direction and discharges the hot water.

The water heater has a burner and a heat exchanger in a housing, and the combustion exhaust gas of a burner that ignites and burns a mixture of fuel gas and combustion air heats water passing through the heat exchanger to generate hot water. Let
The heat exchanger has a heat transfer tube penetrating a plurality of fins arranged side by side in the casing in a lateral direction at a predetermined interval in a meandering manner. Combustion exhaust gas passing between the fins and water flowing in the heat transfer tube. Water can be heated by exchanging heat with.
In such a water heater, in order to prevent the occurrence of drainage inside the heat exchanger when the hot water temperature becomes low and the boiling when the hot water temperature becomes high, there is a heat exchange between the water supply pipe and the hot water discharge pipe. By-pass mixing type that connects the bypass pipe that bypasses the reactor and mixes the water from the bypass pipe with the hot water discharged from the casing of the heat exchanger to maintain the outlet temperature from the casing within an appropriate range. Are known. Patent Documents 1 and 2 also disclose a type in which a bypass pipe is connected between the water supply pipe and the middle of the heat transfer pipe.

Japanese Patent No. 3308437 Japanese Utility Model Publication No. 8-6193

In the above-mentioned conventional bypass mixing type water heater, when connecting the water supply pipe and the hot water discharge pipe by the bypass pipe, the normal water supply pipe and the hot water discharge pipe are separately connected to both side surfaces of the casing, It is necessary to dispose a bypass pipe so as to cross the inside of the housing from side to side. For this reason, there is a possibility that the bypass pipe cannot be laid out due to interference with other components in a narrow space inside the housing, which is required to be compact in recent years.
On the other hand, when connecting between the water supply pipe and the heat transfer pipe, low temperature water is mixed with the hot water in the heat transfer pipe.Therefore, when using the water heater intermittently, the hot water in the heat transfer pipe whose temperature has dropped during operation stop The temperature drops due to the addition of water from the bypass pipe to the underflow of the hot water.

Therefore, an object of the present invention is to provide a water heater in which a bypass pipe can be laid out without interfering with other components even in a narrow space inside a housing, and undershoot during intermittent use can be mitigated. ..

In order to achieve the above-mentioned object, the invention according to claim 1 provides a meandering heat transfer tube which penetrates the inside of the casing in the left-right direction and exposes a plurality of folded-back portions at both left and right ends on left and right side surfaces of the casing. A heat exchanger having, a burner installed below the heat exchanger, which allows combustion exhaust to pass into the casing, and a water supply pipe connected to the inlet side end of the heat transfer pipe on either the left or right side surface of the casing, A hot water supply device comprising: a hot water discharge pipe connected to the discharge side end of the heat transfer pipe on the other side surface of the casing;
It is characterized in that it is provided with a partial bypass pipe that partially connects the heat exchanger by connecting the folded-back portion exposed on the other side surface to the hot water outlet pipe.
According to a second aspect of the present invention, in the configuration of the first aspect, the folded portion to which the partial bypass pipe is connected is the most upstream side of the water flow in the heat transfer tube among the plurality of folded portions exposed on the other side surface. It is characterized by being located in.

According to the first aspect of the present invention, since the folded portion exposed on the side surface of the casing is connected to the hot water outlet pipe and the partial bypass pipe partially bypassing the heat exchanger is provided, a narrow space in the housing is provided. However, the partial bypass pipe can be laid out without interfering with other parts. Further, since the hot and cold water heated to some extent is mixed with the hot water in the hot water outlet pipe, it is possible to alleviate undershoot during intermittent use.
According to the invention described in claim 2, in addition to the effect of claim 1, since the turn-back portion to which the partial bypass pipe is connected is the turn-back portion located on the most upstream side of the water passage in the heat transfer tube, Undershoot and overshoot at the time of intermittent use or when the combustion stage is switched can be alleviated.

It is a front view of the water heater with the front cover removed. It is a perspective view of an inner trunk. It is a front view of an inner trunk. It is the side view which looked at the inner trunk from the right side.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an explanatory view showing an example of a water heater, showing a housing 2 from the front with a front cover on the front removed. The water heater 1 accommodates an inner case 3 in which a combustion device 4, a heat exchanger 5, and an exhaust hood 6 are integrally installed in order from below in a rectangular box-shaped housing 2. .. A gas distribution unit 7 for distributing and supplying a fuel gas to a burner unit (not shown) in the combustion apparatus 4 is attached to the front surface of the combustion apparatus 4, and combustion air is supplied to the burner unit on the lower surface of the combustion apparatus 4. The air supply fan 8 is installed. On the front side of the air supply fan 8 and below the combustion device 4, a controller 9 that accommodates an electrical equipment substrate is erected laterally on the inner bottom surface of the housing 2.

The heat exchanger 5 is provided with a plurality of fins (not shown) inside the square tubular casing 10 at predetermined intervals in the left-right direction, and a heat transfer tube 11 that penetrates each fin in the left-right direction and is continuous in a meandering shape. In addition, heat exchange between the combustion exhaust gas passing between the fins from below and the water flowing in the heat transfer tube 11 is possible. As shown in FIGS. 2 and 3, on the left and right sides of the casing 10, the ends of straight pipes of the heat transfer pipe 11 that pass through each fin in the casing 10 in the left-right direction are alternately connected outside the casing 10. A plurality of U-shaped tubes 12, 12,... As the folded-back portions are exposed.
The exhaust hood 6 is provided with a horizontally elongated oblong exhaust cylinder 13 on the front surface, penetrates the front cover and projects forward, and is capable of discharging the combustion exhaust that has passed through the heat exchanger 5 to the outside.

A gas inlet 14 to which an external gas pipe is connected, a water inlet 15 to which a water pipe is connected, and a hot water outlet 16 to which a pipe to a hot water tap is connected are provided on the lower surface of the housing 2. .. Of these, the gas inlet 14 is connected to the gas distribution unit 7 in the housing 2 via a gas supply unit 17 including a main valve, a proportional valve, and the like. Further, the water inlet 15 is connected to the inlet end of the heat transfer pipe 11 of the heat exchanger 5 located on the left side surface of the casing 10 via the water supply pipe 18. The hot water outlet 16 is connected via a hot water outlet pipe 19 to the outlet end of the heat transfer pipe 11 located on the right side surface of the casing 10.

The combustion device 4 includes a rectangular box-shaped inner case 20 forming a part of the inner case 3, and a burner unit in which a plurality of flat light and dark burners are juxtaposed in the left-right direction. It is accommodated via 21. An upper portion of the front surface of the inner case 20 is provided with a discharge electrode for ignition and a frame rod mounting portion 22 for flame detection, which penetrates through the inner case 20 and projects above the burner unit, and a viewing window 23. ..
The gas distribution unit 7 is assembled on the front surface of the inner case 20 so as to close the opening at the lower front surface of the inner case 20, and the gas supply unit 17 is connected to the rear surface of the lower end.

A partial bypass pipe 24 that connects the heat transfer pipe 11 and the hot water discharge pipe 19 and partially bypasses the heat exchanger 5 is disposed on the right side of the inner case 3. As shown in FIG. 4, the partial bypass pipe 24 is a U-shape in front of the lower stage located on the most upstream side of the heat transfer pipe 11 among the plurality of U-shaped pipes 12 exposed on the right side surface of the casing 10. A pipe that connects the pipe 12 (hereinafter referred to as "12A" in order to distinguish it from other U-shaped pipes 12) and the hot water discharge pipe 19 and has a smaller diameter than the U-shaped pipe 12A and the hot water discharge pipe 19. Is becoming Further, the partial bypass pipe 24 is vertically arranged at a position which overlaps with the hot water discharge pipe 19 in the front-rear direction on the front side of the hot water discharge pipe 19, and as shown in FIG. It does not stick out.

In the water heater 1 configured as described above, when the hot water tap connected to the pipe of the hot water outlet 16 is opened and water is passed through the appliance, the controller 9 that detects this opens the gas flow path of the gas supply unit 17. Is opened to supply the fuel gas from the gas distribution unit 7, and the air supply fan 8 is operated to supply the combustion air. Therefore, the fuel gas supplied from the nozzle of the gas distribution unit 7 is supplied to each concentration burner together with the primary air. Then, when the discharge electrode is continuously discharged by the controller 9, the air-fuel mixture ejected from the flame hole portion of each density burner burns. The combustion exhaust gas of the burner unit is heat-exchanged with the water passing through the heat transfer pipe 11 of the heat exchanger 5 from the water supply pipe 18, becomes hot water of the set temperature, and is discharged from the hot water discharge pipe 19. The controller 9 controls the opening/closing of the gas inlet of the gas distribution unit 7 by operating the solenoid valve of the gas supply unit 17 in accordance with the required combustion amount, thereby gradually controlling the number of burners of the rich and thin burners in the burner unit. To do.

At this time, a part of the hot water flowing in the heat transfer tube 11 and the hot water flowing in the U-shaped tube 12</b>A on the most upstream side flows to the hot water outlet pipe 19 via the partial bypass pipe 24, and thus By setting the diameter and the length, the outlet temperature from the casing 10 can be maintained in an appropriate range in which boiling and drainage are prevented. In particular, the hot water heated on the upstream side of the heat transfer pipe 11 is mixed with the hot water discharged from the hot water discharge pipe 19, so that even if the water heater 1 is used intermittently or the combustion stage of the burner unit is switched to the small side. Undershoot of tap water temperature is alleviated. When the combustion stage is switched to the large side, the overshoot of the tap water temperature is alleviated.
Further, since the partial bypass pipe 24 is connected to the U-shaped pipe 12A on the lower front side of the hot water discharge pipe 19, the partial bypass pipe 24 can be connected without trouble even in a narrow space between the housing 2 and the inner case 3. Further, since the inner body 3 is assembled only on the right side surface side, the assembling work can be easily performed and the visual confirmation after the connection can be surely performed from the front side.

As described above, according to the water heater 1 of the above-described embodiment, the U-tube 12A (folded portion) exposed on the right side surface of the casing 10 and the hot water outlet pipe 19 are connected to partially bypass the heat exchanger 5. By providing the bypass pipe 24, the partial bypass pipe 24 can be laid out without interfering with other components even in a narrow space in the housing 2. Further, since the hot and cold water heated to some extent is mixed with the hot water in the hot water outlet pipe 19, the undershoot at the time of intermittent use can be alleviated.
In particular, here, the U-shaped pipe 12 to which the partial bypass pipe 24 is connected is the U-shaped pipe 12 located on the most upstream side of the water passage in the heat transfer pipe 11 among the U-shaped pipes 12 exposed on the right side surface of the casing 10. Since it is set to 12 A, undershoot and overshoot at the time of intermittent use or when the combustion stage is switched can be alleviated.

The disposition of the partial bypass pipe is not limited to the above-described form, and the diameter and the length may be changed, and the U-shaped pipe to be connected may be changed. If there is no problem in workability, it can be arranged on the rear side of the tap pipe.
Further, the partial bypass pipe may be arranged not only on the right side of the casing but also on the left side face if the hot water outlet pipe is connected to the left side face.
Further, the configuration of the water heater itself is not limited to the above-mentioned form, but may be a latent heat recovery type with a sub heat exchanger, an exhaust hood with an exhaust pipe protruding upward from the housing, a bath circuit or The present invention can be applied to a case where a heating circuit is also provided.

1 ·· Water heater, 2 · · Housing, 3 · · Inner shell, 4 · · Combustion device, 5 · · Heat exchanger, 7 · · Gas distribution unit, 8 · · Air supply fan, 9 · · Controller, 10・・Casing, 11・・Heat transfer pipe, 12,12A・・U-shaped pipe, 17・・Gas supply part, 18・・Water supply pipe, 19・・Hot water pipe, 20・・Inner case, 24・・Partial bypass tube.

Claims (2)

A heat exchanger having a meandering heat transfer tube that penetrates the inside of the casing in the left-right direction and exposes a plurality of folded-back portions at both left and right ends on the left and right side surfaces of the casing,
A burner that is installed below the heat exchanger and that passes combustion exhaust gas into the casing;
A water supply pipe connected to the inlet side end of the heat transfer pipe on one of the left and right side surfaces of the casing;
A hot water supply device comprising a hot water outlet pipe connected to the outlet side end of the heat transfer pipe on the other side surface of the casing,
A water heater comprising a partial bypass pipe that connects the folded-back portion exposed on the other side surface to the hot water outlet pipe and partially bypasses the heat exchanger. The folded-back portion to which the partial bypass pipe is connected is positioned on the most upstream side of the water passage in the heat-transfer pipe among the plurality of folded-back portions exposed on the other side surface. The water heater according to claim 1.

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