JPH10148398A - Hot water supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of heat exchange by passing water in a branched manner to a main heat exchanger and an auxiliary heat exchanger, and controlling the water flow quantity to branched pipes at least according to either the supply quantity of hot water or the combustion quantity of a burner. SOLUTION: Water to be fed is branched on the upstream side of a main heat exchanger 2 and an auxiliary heat exchanger 4, and passed into a water pipe 3 and a branched pipe 5. The water fed into the branched pipe 5 and the water fed into the water pipe 3 is respectively heated in the auxiliary heat exchanger 4 and in the main heat exchanger 2 respectively, and then, merged to each other, and supplied from a hot water supply pipe. A flow rate control valve 9 is provided on the upstream side of the auxiliary heat exchanger 4 in the branched pipe 5 to control the water flow quantity to the main heat exchanger 2 and the auxiliary heat exchanger 4. When the requested quantity of hot water to be supplied is small, and the combustion quantity of a burner is small, the flow rate control valve 9 makes a control so that the water flow quantity to the auxiliary heat exchanger 4 is increased. On the contrary, when the requested quantity of hot water is large, and the combustion quantity of the burner is large, the water flow quantity to the auxiliary heat exchanger 4 is decreased, and the water flow rate to the main heat exchanger 2 is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water heater that improves thermal efficiency by utilizing latent heat of combustion gas.

[0002]

2. Description of the Related Art Conventionally, there has been a method of utilizing the latent heat of a combustion gas to improve the heat efficiency of a heat exchanger. Two heat exchangers are provided upstream and downstream of the combustion gas flow path, and supplied water is supplied in series from the downstream auxiliary heat exchanger to the upstream main heat exchanger.

[0003]

However, when an auxiliary heat exchanger is provided in addition to the main heat exchanger in order to obtain high efficiency as in the prior art, it is necessary to lengthen the water passage in the auxiliary heat exchanger. Therefore, if a configuration is adopted in which water is passed in series to two heat exchangers, the length of the water passage extends about three times as compared with the case where only the main heat exchanger is used, and the water flow resistance increases. . Therefore, it is conceivable to pass water through the main heat exchanger and the auxiliary heat exchanger in parallel.At this time, regardless of the burner combustion, the water flow ratio between the main heat exchanger and the auxiliary heat exchanger is constant. In this case, in addition to a large loss in thermal efficiency, when the exhaust gas temperature of the combustion gas is too low, white smoke or dew is likely to be generated near the exhaust port of the combustion gas due to a decrease in the outside air temperature. Furthermore, even if the neutralization capacity of the neutralization device for neutralizing the strongly acidic drain generated in the auxiliary heat exchanger decreases over time, if the water flow rate to the auxiliary heat exchanger is constant, Since the amount of generated drain is the same as when the neutralizing device has a normal capacity, there is a problem that the drain is drained out of the machine without being sufficiently neutralized.

Accordingly, an object of the present invention is to solve the above-mentioned conventional problems and to provide a water heater capable of efficiently performing heat exchange.

[0005]

To achieve the above object, a water heater according to the present invention comprises a main heat exchanger, an auxiliary heat exchanger,
A water heater provided with a burner, wherein a water supply pipe to the main heat exchanger is branched to reach an auxiliary heat exchanger, and a flow control means for controlling a flow rate of water to the branch pipe is provided. This is the first feature. Further, in the water heater according to the present invention, in addition to the first feature, the flow rate control means controls a water flow rate to the branch pipe according to at least one of a hot water discharge rate and a burner combustion rate. This is the second feature. Further, in the water heater according to the present invention, in addition to the first feature, the flow rate control means is at least one of an outside air temperature detection means, an outside air humidity detection means, and a dew condensation detection means provided near the combustion gas exhaust port. A third feature is that the amount of water flowing to the branch pipe is controlled based on the detected value. Further, the water heater of the present invention includes a main heat exchanger, an auxiliary heat exchanger, a burner, a drain recovery unit for recovering drain generated in the auxiliary heat exchanger, and a neutralization device for neutralizing the recovered drain. A water heater provided with a branch pipe that branches the water supply pipe to the main heat exchanger to the auxiliary heat exchanger, and a neutralization capacity deterioration detection device that detects the deterioration of the neutralization capacity of the neutralization device, A fourth feature is that flow rate control means for controlling the flow rate of water to the branch pipe based on the signal output of the neutralization capability deterioration detection device is provided.

In the water heater of the first aspect, the ratio of the supply water supplied to the main heat exchanger and the auxiliary heat exchanger is controlled by flow rate control means, and the main heat exchanger and the auxiliary heat exchanger are controlled. The hot water heated in each of them is joined again and then discharged. Therefore, when the amount of hot water is insufficient due to the water flow resistance of the auxiliary heat exchanger, the flow of water to the auxiliary heat exchanger is reduced to prioritize securing the amount of hot water, or conversely, until the target thermal efficiency is obtained. It is possible to prioritize the improvement of thermal efficiency by increasing the amount of water flow to the auxiliary heat exchanger, and to optimize the water flow resistance of the auxiliary heat exchanger due to various product variations and the optimum thermal efficiency The water flow rate can be obtained. Further, in the water heater according to the second aspect, the flow rate of the supply water supplied to the main heat exchanger and the auxiliary heat exchanger is controlled by the flow rate control means, and the main heat exchanger and the auxiliary heat exchange are controlled. The hot water heated in each of the vessels joins again and is then discharged. At this time, the amount of water flowing to the branch pipe to the auxiliary heat exchanger is controlled according to at least one of the amount of hot water and the amount of combustion of the burner. Can be achieved. In other words, when a large amount of high-temperature hot water is required, the amount of water flowing to the auxiliary heat exchanger is reduced to reduce the overall water flow resistance, secure the hot water flow, and when a large amount of hot water is not required. Can increase the efficiency by increasing the flow rate of water to the auxiliary heat exchanger. Further, in the water heater according to the third aspect, the flow rate of the supply water flowing through the main heat exchanger and the auxiliary heat exchanger is controlled by the flow rate control means, and the main heat exchanger and the auxiliary heat exchange are controlled. The hot water heated in each of the vessels joins again and is then discharged. At this time, based on at least one of the outside air temperature detecting means, the outside air humidity detecting means, and the dew condensation detecting means provided near the combustion gas exhaust port, the amount of water flowing through the branch pipe to the auxiliary heat exchanger is determined. By controlling the rate of latent heat recovery by the auxiliary heat exchanger,
Heat exchange can be performed efficiently while maintaining the exhaust temperature of the combustion gas at a temperature at which the white smoke phenomenon does not occur. Further, in the water heater according to the fourth aspect, the flow rate of the supply water flowing through the main heat exchanger and the auxiliary heat exchanger is controlled by the flow rate control means, and the main heat exchanger and the auxiliary heat exchange are controlled. The hot water heated in each of the vessels joins again and is then discharged. At this time, the deterioration of the neutralization capability of the neutralization device that neutralizes the drain generated in the auxiliary heat exchanger was detected by the neutralization capability deterioration detection device, and the amount of water flowing to the branch pipe was controlled. When the neutralization capacity is deteriorated, the amount of water passing through the auxiliary heat exchanger is reduced to lower the recovery rate of latent heat, thereby suppressing generation of drain. As a result, it is possible to minimize drainage of insufficient drainage from the machine.

[0007]

FIG. 1 is a side sectional view of a water heater according to a first embodiment of the present invention, FIG. 2 is a side sectional view of a water heater according to a second embodiment of the present invention, and FIG. It is a sectional side view of a water heater showing a 3rd embodiment of the present invention.

In FIG. 1, a water heater according to a first embodiment includes a main heat exchanger 2 upstream of a drain receiver 6 in an exhaust gas passage 7 above a burner 1 and an auxiliary heat exchanger downstream of a drain receiver 6. An exchange 4 is arranged. The supply water is branched upstream of the main heat exchanger 2 and the auxiliary heat exchanger 4, and is passed through the water pipe 3 and the branch pipe 5. The water supplied to the branch pipe 5 is heated by the auxiliary heat exchanger 4 and the water supplied to the water pipe 3 is heated by the main heat exchanger 2 and merged, and then discharged from a hot water supply pipe (not shown). A flow control valve 9 is provided in the branch pipe 5 on the upstream side of the auxiliary heat exchanger 4 to control the flow of water to the main heat exchanger 2 and the auxiliary heat exchanger 4. The feed water passed through the water pipe 3 is heated by the high-temperature combustion gas in the main heat exchanger 2, while the feed water passed through the branch pipe 5 is heated by the auxiliary heat exchanger 4 in the main heat exchanger 2. Is heated by the combustion gas after the heating action, that is, utilizing the exhaust heat.

When the required hot water output is small and the burner combustion is small, the flow control valve 9 controls the flow of water to the auxiliary heat exchanger 4 so as to increase the heat exchange efficiency. be able to. Conversely, if the required hot water output is large and the burner combustion is large, the auxiliary heat exchanger 4
In order to prevent the required amount of hot water from being unable to be secured due to the water flow resistance, the amount of flowing water to the auxiliary heat exchanger 4 is reduced and the ratio of flowing water to the main heat exchanger 2 is increased to secure the amount of hot water. The thermal efficiency can be improved within the range that can be achieved.

Referring to FIG. 2, a water heater according to a second embodiment includes a main heat exchanger 2 upstream of a drain receiver 6 in an exhaust gas passage 7 above a burner 1 and an auxiliary heat exchanger downstream of a drain receiver 6. An exchange 4 is arranged. The supply water is branched upstream of the main heat exchanger 2 and the auxiliary heat exchanger 4, and is passed through the water pipe 3 and the branch pipe 5. The water supplied to the branch pipe 5 is heated by the auxiliary heat exchanger 4 and the water supplied to the water pipe 3 is heated by the main heat exchanger 2 and merged, and then discharged from a hot water supply pipe (not shown). Also, among the outside air temperature sensor 20, the outside air humidity sensor 21, and the dew condensation sensor 22 near the combustion gas exhaust port,
At least one of them is provided, and the flow rate to the main heat exchanger 2 and the auxiliary heat exchanger 4 is controlled by the flow control valve 9 provided in the branch pipe 5 based on the detection value of each sensor. For example,
When the temperature detected by the outside air temperature sensor 20 becomes equal to or lower than a predetermined temperature, the amount of water passing through the auxiliary heat exchanger 4 is reduced, and the recovery rate of latent heat by the auxiliary heat exchanger 4 is reduced, so that the exhaust gas temperature of the combustion gas is reduced to a certain temperature. By keeping the above, it is possible to prevent the generation of white smoke and dew near the exhaust port. The recovery rate of latent heat may be reduced stepwise with a decrease in outside air temperature, or when the outside air temperature reaches a predetermined temperature, it is continuously reduced in proportion to the subsequent temperature decrease. Is also good. Similarly, when the outside air humidity sensor 21 or the condensation sensor 22 detects the occurrence of humidity or condensation above a predetermined value, the flow rate control valve 9 reduces the flow rate of water to the auxiliary heat exchanger 4 to reduce the recovery rate of latent heat. To reduce the

Referring to FIG. 3, a water heater according to a third embodiment includes a main heat exchanger 2 upstream of a drain receiver 6 in an exhaust gas passage 7 above a burner 1 and an auxiliary heat exchanger downstream of a drain receiver 6. An exchange 4 is arranged. The supply water is branched upstream of the main heat exchanger 2 and the auxiliary heat exchanger 4, and is passed through the water pipe 3 and the branch pipe 5. The water supplied to the branch pipe 5 is heated by the auxiliary heat exchanger 4 and the water supplied to the water pipe 3 is heated by the main heat exchanger 2 and merged, and then discharged from a hot water supply pipe (not shown). When water is heated using the exhaust heat in the auxiliary heat exchanger 4, the water in the combustion gas is condensed to generate drain. This drain shows strong acidity because the components of the combustion gas are dissolved, and if drained as it is, the drainage path and structures may be corroded. It is neutralized by the summing device 8. A pH sensor 25 is provided in the drainage path of the neutralized drain. When the neutralization treatment capacity decreases over time, the acidity of the drain drained increases, but the auxiliary heat exchanger 4 is controlled by the flow control valve 9 provided in the branch pipe 5 according to the detection value of the PH sensor. The amount of drainage can be reduced by reducing the amount of water passing through the auxiliary heat exchanger 4 and decreasing the recovery rate of latent heat by the auxiliary heat exchanger 4. Therefore, before the hot water heater continues to operate, the neutralizer is activated by a warning sound or warning on the display of the remote control of the water heater before the strongly acidic drain corrodes the drainage passages and structures. Replacement of the neutralizing agent can be encouraged.

The neutralization capability deterioration detecting device is not limited to the PH sensor, and the sensor portion is made of a conductive metal material, and the neutralization process is performed by detecting a change in the electric resistance of the sensor portion which is corroded by the drain. You may make it detect the fall of capability.

The flow control valve 9 may be provided in the water pipe 3 downstream of the branch between the water pipe 3 and the branch pipe 5 and upstream of the junction.

[0014]

The water heater of the present invention having the above-described structure has the following effects. That is, in the water heater according to the first aspect, the branch water flows through the main heat exchanger and the auxiliary heat exchanger, and the flow control unit that controls the amount of water flowing through the branch pipe to the auxiliary heat exchanger is provided. If the amount of hot water is insufficient due to the flow resistance of the auxiliary heat exchanger,
Reduce the amount of water flowing to the auxiliary heat exchanger to give priority to securing the hot water output, or increase the amount of water flowing to the auxiliary heat exchanger to give priority to improving the thermal efficiency until the target thermal efficiency is obtained. It is possible to efficiently obtain the required hot water flow rate by always securing the optimal water flow rate to each heat exchanger corresponding to the water flow resistance of the auxiliary heat exchanger and the target thermal efficiency. be able to. Therefore, under the same conditions of the set temperature and the amount of hot water, the required amount of combustion of the burner can be reduced as compared with a case where the control of the flow rate of water to the auxiliary heat exchanger is not performed, so that the gas consumption is reduced. be able to. As a result, the load at the time of combustion of the burner is reduced and a margin is generated, so that the combustion section including the burner can be downsized, and the water heater as a whole can be downsized. Further, in the water heater according to claim 2, the flow rate control means controls the amount of water flowing to the branch pipe according to at least one of the amount of hot water and the amount of combustion of the burner. That is, when the required amount of hot water is small and the combustion amount of the burner is small, heat exchange can be performed efficiently by controlling the flow rate control means to increase the flow rate of water to the auxiliary heat exchanger. . Conversely, when the required hot water output is large and the burner combustion is large, the auxiliary heat exchanger is reduced by reducing the water flow to the auxiliary heat exchanger and increasing the water flow to the main heat exchanger. To prevent the required amount of hot water from being unable to be secured due to the water flow resistance.
Thermal efficiency can be improved within a range in which the amount of hot water can be secured. Further, in the water heater according to claim 3, the flow rate control means is configured to perform the branching based on a detection value of at least one of an outside air temperature detection means, an outside air humidity detection means, and a dew condensation detection means provided near a combustion gas exhaust port. By controlling the water flow through the pipes, the efficiency of latent heat recovery by the auxiliary heat exchanger is adjusted, and heat is efficiently exchanged while maintaining the exhaust gas temperature of the combustion gas at a temperature at which white smoke does not occur. be able to. Further, in the water heater according to claim 4, the flow rate control means controls the flow rate of the branch pipe based on the signal output of the neutralization capacity deterioration detecting device. It is possible to reduce the amount of water flowing into the tank and reduce the recovery rate of latent heat, thereby suppressing drainage. As a result, drainage of insufficiently neutralized drainage can be minimized.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a water heater showing a first embodiment of the present invention.

FIG. 2 is a side sectional view of a water heater according to a second embodiment of the present invention.

FIG. 3 is a side sectional view of a water heater showing a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Burner 2 Main heat exchanger 3 Water pipe 4 Auxiliary heat exchanger 5 Branch pipe 6 Drain receiver 7 Exhaust gas flow path 8 Neutralizer 9 Flow control valve 20 Outside air temperature sensor 21 Outside air humidity sensor 22 Dew condensation sensor 25 PH sensor

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hidenori Hata 93, Edo-cho, Chuo-ku, Kobe-shi, Hyogo Pref. (72) Inventor Itsuo Nagai 93, Edo-cho, Chuo-ku, Kobe-shi, Hyogo (72) Inventor Ryoji Kutsuna 93, Edo-cho, Chuo-ku, Kobe, Hyogo Prefecture Inside Noritz Co., Ltd. (72) Inventor Takahiro Matsuda 93, Edo-cho, Chuo-ku, Kobe City, Hyogo Pref.

Claims (4)

[Claims] 1. A water heater comprising a main heat exchanger, an auxiliary heat exchanger, and a burner, wherein a water supply pipe to the main heat exchanger branches to a branch pipe leading to the auxiliary heat exchanger. And a flow control means for controlling a flow rate of water to the branch pipe. 2. The water heater according to claim 1, wherein the flow control means controls the amount of water flowing to the branch pipe according to at least one of the amount of hot water and the amount of combustion of the burner. . 3. The flow control means according to claim 1, wherein said flow rate control means is connected to said branch pipe based on at least one of an outside air temperature detecting means, an outside air humidity detecting means and a dew condensation detecting means provided near a combustion gas exhaust port. The water heater according to claim 1, wherein an amount of water is controlled. 4. A main heat exchanger, an auxiliary heat exchanger, a burner, a drain recovery section for recovering drain generated in the auxiliary heat exchanger, and a neutralization device for neutralizing the recovered drain. A water heater, a branch pipe branching from a water supply pipe to the main heat exchanger and leading to the auxiliary heat exchanger, and a neutralization capacity deterioration detection device for detecting deterioration of the neutralization capacity of the neutralization device. And a flow control means for controlling a flow rate of water to the branch pipe based on a signal output of the neutralization capability deterioration detecting device.