JP2020008217A - Water heater with instantaneous hot water function - Google Patents

Abstract

To prevent lowering of a hot water tapping temperature caused by a backflow of water in an external pipeline, and to easily execute air-bleeding and drainage even when a non-self-priming type is used as a circulation pump.SOLUTION: A water heater 1 with instantaneous hot water function includes: a burner unit 6 and a heat exchanger 7; a water supply pipe 19 connected to the heat exchanger 7; a hot water tapping pipe 20 connected to the heat exchanger 7; and a return pipe 21 connected to the water supply pipe 19, and having a circulation pump 22. A check valve 29 is provided on the downstream side of the circulation pump 22 in the return pipe 21, and between the circulation pump 22 and the check valve 29 in the return pipe 21, a branch pipe 27 which can be opened to the outside of the fixture is connected.SELECTED DRAWING: Figure 6

Description

  TECHNICAL FIELD The present invention relates to a hot water supply device with a hot water function that circulates hot water between an external pipe and a pipe in an appliance and heats the hot water with a heat exchanger so that the hot water can be supplied immediately from a hot water tap of the external pipe.

  2. Description of the Related Art There is known a water heater having a hot water function by connecting a return pipe equipped with a circulation pump to a water supply pipe connected to a heat exchanger (for example, see Patent Document 1). In this hot water supply device with a hot water function, a circulation path is formed between the tapping pipe, the external pipe, the return pipe, and the water supply pipe by connecting the tapping pipe and the return pipe with an external pipe, and the circulation path is circulated through the circulation path. Heating operation is possible by heating with a heat exchanger while circulating hot and cold water with a pump. Therefore, when the hot water tap provided on the external pipe is opened, hot water can be immediately supplied.

JP-A-2004-286397

In this hot water supply with hot water function, since the pressure loss in the heat transfer pipe of the heat exchanger is large, water in the water supply pipe may flow backward in the return pipe and flow to the external pipe. Hot water is discharged at a lower temperature.
On the other hand, pumps are classified into a self-priming type and a non-self-priming type depending on the presence or absence of self-priming ability.However, the non-self-priming type pump has higher pressure resistance and maximum working fluid temperature than the self-priming type pump, A non-self-priming type is suitable as a circulating pump for a hot-water supply water heater.
However, the non-self-priming type pump needs to fill the entire pump including the suction side with priming water, and since there is no air separation chamber, it is necessary to bleed air during construction. In addition, if it is not used for a long time in winter, it may freeze if water is not drained.

  Therefore, the present invention prevents the drop of tap water temperature due to the backflow of water to the external piping, and can easily perform air bleeding and water bleeding even if a non-self-priming type is used as a circulating pump, thereby preventing construction and freezing. It is an object of the present invention to provide a hot water supply device with an instant hot water function that can easily perform a hot water supply.

Means for Solving the Problems To achieve the above object, an invention according to claim 1 includes a burner and a heat exchanger, a water supply pipe connected to the heat exchanger, a hot water pipe connected to the heat exchanger, and a water supply pipe connected to the water supply pipe. And a return pipe provided with a circulation pump, and by connecting the tapping pipe and the return pipe with an external pipe, hot water discharged from the tapping pipe returns to the return pipe via the external pipe, and from the water supply pipe. A water heater with a hot water function in which a circulation path leading to the heat exchanger is formed,
A check valve is provided downstream of the circulation pump in the return pipe, and a branch pipe openable to the outside of the device is connected between the circulation pump and the check valve in the return pipe.
According to a second aspect of the present invention, in the configuration of the first aspect, the branch pipe is formed integrally with a part of the pipe forming the return pipe.
According to a third aspect of the present invention, in the configuration of the second aspect, the check valve is provided in a part of the piping.

According to the first aspect of the present invention, the check valve is provided in the return pipe on the downstream side of the circulation pump, and the branch pipe can be opened to the outside of the device between the circulation pump and the check valve in the return pipe. The check valve prevents a drop in tapping temperature due to backflow of water to the external piping by the check valve, and facilitates air bleeding and draining by the branch pipe even if a non-self-priming type circulating pump is used. Construction and freezing prevention can be easily performed.
According to the second aspect of the invention, in addition to the effect of the first aspect, since the branch pipe is formed integrally with a part of the pipe forming the return pipe, the branch pipe can be easily connected to the return pipe. Can be provided.
According to the third aspect of the invention, in addition to the effect of the second aspect, since the check valve is also provided in the horizontal pipe, it can be easily installed as a unit including the branch pipe and the check valve.

It is a front view of a water heater. It is a bottom view of a water heater. It is a front view in the state where the front cover was removed. It is the enlarged view of the housing lower part which looked at the return pipe from the front. It is sectional drawing of the check valve part in a return pipe. It is the schematic of a hot water system.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a front view showing an example of a hot water heater with a hot water function (hereinafter simply referred to as “hot water heater”), and FIG. 2 is a bottom view. The water heater 1 has a housing 2 including a box body 3 having five closed surfaces except the front surface, and a front cover 4 having a closed front surface of the box body 3. As shown in FIG. 3 with the front cover 4 removed, a combustion device 5 including a burner unit 6, a heat exchanger 7, and an exhaust hood 8 is installed in the housing 2 from below. An exhaust pipe 9 provided at the upper end of the box main body 3 projects upward through the upper plate of the box body 3. At the top and bottom of the back of the box body 3, mounting brackets 10, 10 for installation on an indoor wall or the like are provided, and a plurality of air supply ports 11, 11,. I have.
At the bottom of the box body 3, a tubular gas connection port 12 to which an external gas pipe is connected, a tubular water supply port 13 to which an external water supply pipe is connected, and a tubular gas connection to which an external hot water supply pipe is connected. A hot water supply connection port 14 and a tubular return connection port 15 are provided.

The burner unit 6 includes a plurality of burners (not shown) therein. The burner unit 6 is connected to a gas connection port 12 to supply fuel gas to the burners, and includes a gas pipe 16 having a base valve and a proportional control valve (not shown). A fan 17 for connection and supplying combustion air to the burner is provided.
The heat exchanger 7 has a heat transfer tube 18 that penetrates a plurality of fins (not shown) in a meandering shape, and a water supply tube 19 connected to the water supply connection port 13 is connected to an input end of the heat transfer tube 18. A tapping pipe 20 connected to the hot water supply connection port 14 is connected to an outlet end of the heat transfer pipe 18.

  A return pipe 21 is connected between the return connection port 15 and the water supply pipe 19. As shown in FIG. 4, the return pipe 21 includes a tubular return connection port 15, a non-self-priming circulating pump 22 in which a downward suction pipe 22 a is connected to the return connection port 15, and a circulating pump 22. A horizontal pipe 23 having an upstream end connected to the horizontal discharge pipe 22b; and a branch pipe section 25 connected to the downstream end of the horizontal pipe 23 and branching laterally from a relay pipe 24 forming a part of the water supply pipe 19. Consists of By connecting the ends of the pipes with the clips 26, 26,..., A return pipe 21 connected from the return connection port 15 to the relay pipe 24 is formed. The upper and lower ends of the relay tube 24 are also connected by clips 26, respectively.

The horizontal pipe 23 is provided with a downward branch pipe 27. The branch pipe 27 has a lower end connected to the bottom plate of the box body 3 and has a lower end opened to the outside. A plug 28 is screwed and fixed to the lower end from below so that the lower end can be arbitrarily opened. I have.
Further, as shown in FIG. 5, a check valve 29 is provided at the downstream end of the horizontal pipe 23 to prevent the water from flowing backward from the water supply pipe 19 to the circulation pump 22 side.
Here, the horizontal pipe 23 and the branch pipe 27 are integrally formed to form a T-shaped unit in which a check valve 29 is incorporated in the horizontal pipe 23, so that the horizontal pipe 23 and the branch pipe 27 can be easily installed and removed in the instrument. . In particular, since the relay pipe 24 is also attached separately as a part of the water supply pipe 19, the circulation pump 22, the T-shaped pipe (the horizontal pipe 23 with the check valve 29 and the branch pipe 27), the relay pipe 24 and Can be easily added to the existing water heater as a circulation path forming unit U.

FIG. 6 schematically shows a hot water system 40 using the water heater 1, and omits components other than those relating to the circulation path. Reference numeral 30 denotes a bypass pipe that connects between the water supply pipe 19 and the tapping pipe 20 and bypasses the heat exchanger 7.
The hot water system 40 is constructed by connecting an external pipe 41 having a plurality of hot water taps 42 between the hot water supply connection port 14 and the return connection port 15. Thus, a circulation path is formed in which the hot water discharged from the tapping pipe 20 returns to the return pipe 21 through the external pipe 41 and returns to the heat exchanger 7 via the water supply pipe 19. Therefore, by burning the burner with the burner unit 6 while circulating hot water in the circulation path by the operation of the circulation pump 22, it is possible to perform a heat retention operation at a set temperature set by a controller (not shown) provided in the appliance. . That is, hot water can be supplied immediately by opening any of the hot water taps 42.

In the water heater 1 configured as described above, it is necessary to bleed air from the non-self-priming circulating pump 22 at the time of construction, and thus the circulating pump 22 is detached with the plug 28 loosened or removed. Perform a test run to drive and circulate water. Then, the air in the pipe is pushed out by the water flowing through the circulation path, reaches the return pipe 21 from the external pipe 41, and is discharged from the branch pipe 27 through the circulation pump 22. Therefore, air can be easily removed. At this time, since the water pressure from the water supply pipe 19 is applied to the check valve 29 on the downstream side of the branch pipe 27, most of the air in the pipe is discharged from the branch pipe 27 without passing through the check valve 29.
In addition, even when the plug 28 is not used for a long time in winter, if the plug 28 is loosened or removed, the drainage from the circulation pump 22 and the return pipe 21 can be easily performed via the branch pipe 27.
On the other hand, when the heat retaining operation is performed by incorporating it into the hot water system 40, even if the pressure loss in the heat transfer tube 18 of the heat exchanger 7 increases, the return pipe 21 is provided with the check valve 29. There is no possibility that the water in the pipe 19 flows backward in the return pipe 21 and flows to the external pipe 41.

As described above, according to the water heater 1 of the above-described embodiment, the check valve 29 is provided on the return pipe 21 on the downstream side of the circulation pump 22, and between the circulation pump 22 and the check valve 29 on the return pipe 21. Since the branch pipe 27 which can be opened to the outside of the appliance is connected, the check valve 29 can prevent a drop in tap water temperature due to the backflow of water to the external pipe 41, and use a non-self-priming type as the circulation pump 22. Even so, air bleeding and water bleeding can be easily performed by the branch pipe 27, and construction and freezing prevention can be easily performed.
Particularly, here, the branch pipe 27 is formed integrally with a part of the pipe (the horizontal pipe 23) forming the return pipe 21, so that the branch pipe 27 can be easily provided on the return pipe 21.
Further, since the check valve 29 is also provided in the horizontal pipe 23, it can be easily installed as a unit including the branch pipe 27 and the check valve 29.

In the above embodiment, the check valve is provided on the horizontal pipe, but may be provided on the branch pipe of the relay pipe.
Further, the return pipe is divided into a return connection port, a circulation pump, a horizontal pipe, and a branch pipe portion of a relay pipe, and the branch pipe is provided integrally with the horizontal pipe. However, the present invention is not limited to this. The division form can be changed as appropriate, such as integrally providing the branch pipe part or connecting the horizontal pipe and the branch pipe separately.
Further, the configuration of the water heater other than the return pipe is not limited to the above-described embodiment, and may be a latent heat recovery type having a sub heat exchanger, a composite type having a heating circuit for a hot water supply side and a bath side or a heating side, or the like. The present invention is applicable.

  1. Hot water supply with hot water function, 2. Housing, 3. Box body, 4. Front cover, 5. Combustion device, 6. Burner unit, 7. Heat exchanger, 8. Exhaust hood, 9 exhaust pipe, 12 gas connection port, 13 water supply connection port, 14 hot water connection port, 15 return port, 16 gas pipe, 19 water pipe, 20 .. tapping pipe, 21. return pipe, 22 .. circulation pump, 23 .. horizontal pipe, 24 .. relay pipe, 27 .. branch pipe, 28 .. plug, 29 .. check valve, 40 .. Hot water system, 41 ... external piping, 42 ... hot water tap.

Claims (3)

A burner and a heat exchanger;
A water supply pipe connected to the heat exchanger,
Tapping pipe connected to the heat exchanger,
A return pipe connected to the water supply pipe and provided with a circulation pump,
By connecting the tapping pipe and the return pipe with an external pipe, hot water discharged from the tapping pipe returns to the return pipe via the external pipe, and a circulation path from the water supply pipe to the heat exchanger. A hot water supply with a hot water function, wherein
A check valve is provided downstream of the circulation pump in the return pipe,
A hot water supply device with a hot water function, wherein a branch pipe that can be opened to the outside of the appliance is connected between the circulation pump and the check valve in the return pipe.   2. The hot water supply device with a hot water function according to claim 1, wherein the branch pipe is formed integrally with a part of the pipe forming the return pipe. 3.   The hot water supply device with a hot water function according to claim 2, wherein the check valve is provided in the partial pipe.

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