JPH10115463A - Hot water supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot water supply apparatus for obtaining hot water of stable temperature even at the time of restarting a discharge of hot water after a discharge of hot water is stopped without giving adverse influence to durability of a heat exchanger. SOLUTION: The water heater comprises a burner 1, a heat exchanger 3, a water flow passage provided with the exchanger 3, and a heating means for intermittently igniting the burner even during hot water supply stopping to heat the exchanger 3 for keeping temperature. In this case, a hot water detecting means for detecting presence or absence of hot water in the exchanger in a non-burning state before the heating means is operated is provided to thereby inhibit the operation of the heating means when no hot water exists in the exchanger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water heater for stabilizing the temperature of hot water at the time of re-starting hot water.

[0002]

2. Description of the Related Art When tapping is stopped after using a water heater, the hot water in the heat exchanger is gradually cooled. After the hot water in the heat exchanger cools down, hot water at a temperature much lower than the set temperature of hot water supply comes out first, and then the hot water at the set temperature comes out due to the combustion heating of the heat exchanger. There is a problem that the temperature variation gives a discomfort to the user of the hot water.

In order to solve such a problem, the present applicant has previously provided a heat retaining means for controlling intermittent heating of a heat exchanger after stopping hot water supply according to Japanese Patent Application No. 8-200309. Prior to this, there is provided a discriminating means for controlling the heating of the heat exchanger for a predetermined time to determine the presence or absence of hot water in the heat exchanger from the detection output of the temperature sensor attached to the heat exchanger. In such a case, a water heater that enables the heat retaining means to perform the heat retaining operation, while prohibiting the heat retaining means from operating when it is determined that there is no hot water, has been proposed.

[0004]

However, in the above-described apparatus, the heat exchanger is heated for a predetermined time even when there is no hot or cold water in the heat exchanger. Water heaters are often drained at the time of construction or due to long-term absence, etc.Therefore, if the water heater is operated in this state, the heat exchanger will be empty for a short time, This has adversely affected the durability of the heat exchanger.

[0005] The present invention solves the above-mentioned problems, and can provide hot water having a stable temperature even at the time of re-watering after the stop of hot water supply.
It is an object of the present invention to provide a water heater that does not adversely affect the durability of the heat exchanger.

[0006]

In order to achieve the above object, a water heater according to the present invention comprises a burner, a heat exchanger, and a water passage interposed between the heat exchanger, and the heat exchanger intermittently when the hot water supply is stopped. A water heater provided with a heat retaining means for heating the water, provided with hot water detecting means for detecting the presence or absence of hot water in the heat exchanger in a non-combustion state when hot water is stopped, and when hot water is detected by the hot water detecting means, A first feature is that control means is provided for enabling the heat retaining means to be operable and prohibiting the operation of the heat retaining means when no hot or cold water is detected. According to this water heater, the presence or absence of hot water in the heat exchanger is detected without performing combustion heating before the warming means is operated after the hot water is stopped. Operation will be prohibited. Therefore, there is no occurrence of an empty firing state of the heat exchanger, so that the durability of the heat exchanger is not adversely affected.

In the water heater of the present invention, in addition to the first feature, the hot water detecting means includes a temperature sensor attached to the water passage, a current control unit for varying a current supplied to the temperature sensor, and the temperature sensor. And a hot water judging unit for judging the presence or absence of hot water based on the detection result of the resistance value detecting unit when detecting a resistance value of the temperature sensor when a large current is supplied to or after a large current is supplied to the temperature sensor. This is the second feature. According to this water heater, the presence or absence of hot water can be detected without adding a new member to the hot water detecting means and without heating the heat exchanger, so that the durability of the heat exchanger is not adversely affected. Besides, the cost of the water heater is not increased.

Further, in the water heater according to the present invention, in addition to the first feature, the hot water detecting means includes a temperature sensor and an anti-freezing heater attached to the water passage, an energizing section for the anti-freezing heater, and the anti-freezing heater. A third feature is that the resistance value detecting unit detects a resistance value of the temperature sensor when or after power is supplied to the heater and a hot water determination unit that determines presence or absence of hot water based on a detection result of the resistance value detecting unit. I have. According to this water heater, the presence or absence of hot water can be detected without adding a new member to the hot water detecting means and without heating the heat exchanger in the same manner as the second feature. It does not adversely affect water quality and does not increase the cost of the water heater.

In the water heater of the present invention, in addition to the first feature, the hot water detecting means includes a float type water level detector disposed in the water passage and a presence / absence of hot water based on a detection result of the water level detector. The fourth feature is that the determination unit is constituted by a hot and cold determination unit. According to this water heater, the presence or absence of hot water can be detected only by disposing a float type water level detector in the water passage, so that the durability of the heat exchanger is not adversely affected as in the fourth feature. In addition, since the configuration of the control is not complicated, the cost of the water heater is not increased.

Further, in the water heater according to the present invention, in addition to the first feature, the hot water detecting means may include an electrode type water level detector disposed in the water passage and the presence or absence of hot water based on the detection result of the water level detector. The fifth feature is that the determination unit is constituted by a hot and cold determination unit. According to this water heater, the presence or absence of hot water can be detected only by disposing the electrode type water level detector in the water passage, so that the durability of the heat exchanger is not adversely affected as in the fourth feature. In addition, since the configuration of the control is not complicated, the cost of the water heater is not increased.

[0011]

FIG. 1 is an overall configuration diagram showing an embodiment of a water heater according to the present invention. FIG. 2 is an explanatory diagram of hot water temperature control by the heat retaining means according to the embodiment of the water heater of the present invention.
FIG. 3 is a schematic flowchart of the overall control according to the embodiment of the water heater of the present invention. FIG. 4 shows a second embodiment of the water heater of the present invention.
FIG. 6 is a circuit diagram of a current control unit and a resistance value detection unit that vary the current supplied to the temperature sensor and constitute an embodiment of the hot and cold water detection unit which is a feature of the present invention. FIG. 5 is an explanatory diagram showing a change of hot water in a water passage by hot water detecting means which is a second feature of the water heater of the present invention.

As shown in FIG. 1, the water heater comprises a burner 1, a combustion chamber 2, a heat exchanger 3, and a fan 4. The fuel gas is supplied to the burner 1 through the hot water supply capacity switching solenoid valves 5, 6, and 7, and is mixed with the combustion air supplied from the fan 4 to form a flame in the burner 1 and burn. The ignition of the fuel gas is performed by a spark plug 10. The high-temperature combustion gas generated by the combustion is passed through the heat exchanger 3 to the water passage 12.
The water sent from a is heated and supplied to the curran 13 as hot water from the water passage 12b. The combustion gas after heating the water is exhausted outside the vessel. In addition, 9 is an embers safety device and 11 is a flame detection device.

In the water heater having such a configuration, according to the control method conventionally used, when the curan 13 is opened and the water amount detecting device 15 detects the minimum operating water amount (hereinafter referred to as MOQ) or more, the fan 4 Is started, a fuel gas is supplied to the burner 1 with a predetermined delay time, and the fuel is ignited and burned by the spark plug 10. The amount of combustion air and the amount of fuel gas are set so that the tapping temperature detected by the temperature sensor (tapping thermistor) 16 provided on the tapping pipe 12b is set to the set temperature set by the temperature setting means of the remote controller of the water heater (not shown). Control. Further, when the curan 13 is closed and the water amount detected by the water amount detection device 15 falls below the MOQ and the tapping stops, the gas solenoid valve 18 provided upstream of the hot water supply capacity switching solenoid valves 5, 6, 7 is closed to extinguish the fire. Fan 4 returns to Kallang 1
When the ignition switch 3 is opened, a fan standby operation for maintaining the air volume at the time of ignition is performed for a predetermined time after the extinguishing so that the ignition operation can be performed immediately, and the operation is stopped after a predetermined time.

Then, the presence or absence of hot water in the heat exchanger 3 is determined by the hot water detecting means. When the determination means determines that hot water is present, the heat switch provided in the remote control device is turned on. Means that the intermittent ignition of the burner 1 after the stoppage of the hot water activates the heat retaining means for heating and maintaining the heat exchanger, thereby preventing the cooling of the hot water staying in the heat exchanger and, therefore, stabilizing when the hot water is again supplied. It supplies hot water at the temperature. If the heat keeping means is not operated when the heat keeping switch is turned off, no fuel gas is consumed during the stoppage of hot water supply, and no noise is generated when the burner is ignited. For example, when using a water heater in an ordinary household, if there is a family member who does not need the hot water function, if you are worried about noise when bathing late at night, if you want to save fuel gas, etc. It is possible not to operate the heat retaining means.

As shown in FIG. 2, the heat retaining means sets an ignition time for intermittently igniting the burner 1 to a relatively short time in order to prevent boiling of hot water in the heat exchanger, and to set an ignition interval. Is variable according to the difference between the incoming water temperature detected by a temperature sensor (incoming water thermistor) 14 provided in the water pipe 12a and the set temperature of the remote control device. For example, the ignition time is set to 5 seconds, the interval is 30 minutes when the incoming water temperature is 20 ° C and the set temperature is 40 ° C, and the interval is 30 seconds when the incoming water temperature is 5 ° C and the set temperature is 40 ° C. In addition, the greater the difference between the incoming water temperature and the set temperature, the shorter the interval, and the smaller the difference, the longer the interval, the less waste of fuel. Alternatively, the ignition time may be varied within a range of several seconds according to the difference between the incoming water temperature and the set temperature as described above, or a temperature sensor may be provided in the heat exchanger 3 and the temperature detected by the temperature sensor may be changed. Fire may be extinguished when a predetermined temperature is detected. In addition, an outside air temperature may be used instead of the above-mentioned incoming water temperature.

Further, when the burner 1 is ignited intermittently, the amount of combustion must be suppressed as much as possible to prevent boiling of the hot water in the heat exchanger 3. Therefore, at the time of intermittent ignition, only the hot water supply capacity switching electromagnetic valve 7 is opened to burn with the minimum unit of hot water supply capacity. Further, the gas pressure may be controlled by the proportional valve 17 to, for example, the minimum gas pressure. In addition, the thermal insulation means controls its operation with a thermal insulation switch provided in the remote control device, and arbitrarily sets the operation time zone with the remote control device,
The heat retaining means can be operated during the set time period. Therefore, if the heat retention means is automatically activated during the bathing time period, which is almost constant every day, or during the morning and evening when the water heater is frequently used, it will be more efficient and stable in accordance with the usage of the water heater Hot water at a constant temperature can be supplied, and noise can be suppressed only during a certain period of time.

FIG. 3 is a schematic flowchart of the overall control according to the embodiment of the water heater of the present invention. When the operation switch of the remote control device is turned on and the water heater is in the hot water standby state (S1), the hot water detecting means for detecting the presence or absence of hot water in the heat exchanger according to the present invention operates (S2), and the hot water is turned off. If it is detected, the above-mentioned heat retaining means is activated (S3). During the operation of the heat retaining means, the water heater 13 is opened, and if water passing above the MOQ is detected (S4), the water heater stops the heat retaining operation. Hot water is supplied (S5), and if water is not detected (S4), the process returns to the step (S2) of detecting the presence or absence of hot water. On the other hand, if hot water is not detected in step (S2), the process proceeds to water flow detecting step (S6). If water flow equal to or higher than MOQ is detected, the water heater turns on hot water (S5) and no water flow is detected. Then, the process returns to the step of detecting hot and cold water (S2).

FIG. 4 shows an embodiment of the invention of claim 2 which is a hot and cold water detecting means according to the present invention.
4A is a time chart, and FIG.
FIG. 4C is a circuit diagram of a current control unit and a resistance value detection unit for varying the current supplied to the temperature sensor 16, and FIG. 4C illustrates another modified circuit of the current control unit and the resistance value detection unit for varying the current supplied to the temperature sensor 16. FIG. FIG. 5 is an explanatory diagram showing a change in detected temperature of the temperature sensor 16 by the hot and cold water detecting means according to the second aspect of the invention.

In FIG. 4 (a), a current control section B1 constituting the hot and cold water detecting means A1 alternately controls a period T1 for supplying a large current to the temperature sensor 16 and a period T2 for supplying a small current. For example, a large current supply time T1 of 3 seconds
And a small current supply time T2 of 30 seconds to 60 seconds are repeatedly set. As shown in FIG.
During the large current supply time T1 for 2 seconds, the applied voltage (24 V) is applied to the switch 2 to the temperature sensor 16 (negative thermistor).
1 is connected to the series circuit of the resistor 22 and the temperature detector 16 via the switch 21 during the small current supply time T2.
3 is added to the series circuit of the temperature sensor 16 and the resistance value of the resistor 22 is set to be extremely small as compared with the resistance value of the resistor 23. From second to 60 seconds, a small current (for example, 1 mA) flows through the temperature sensor 16. still,
Reference numeral 24 denotes a resistance value detection unit C1 connected in parallel to the temperature sensor 16.
Is a voltmeter.

FIG. 5 (a) shows a change in the detection voltage of the temperature sensor 16 after the temperature sensor 16 is energized at 100 milliamps for 3 seconds while hot water is present in the heat exchanger 3.
FIG. 5B shows a change in the detection voltage of the temperature sensor 16 after energization under the same conditions in a state where there is no hot or cold water in the heat exchanger 3. In FIG. 5A where hot water is present, it is necessary to return to a detection temperature (voltage) higher by 0.5 degrees than the detection temperature (voltage) of the temperature sensor 16 at the start of the large current supply after the stop of the large current supply. Fig. 5 (b), which requires seconds and has no hot water
It can be seen that it takes 29 seconds to return to the detection temperature (voltage) 0.5 degrees higher than the detection temperature (voltage) of the temperature sensor 16 at the start of the large current supply after the stop of the large current supply. Therefore, the hot water judging section (not shown) applies a large current to the temperature sensor 16 for 3 seconds to self-heat, then detects a temperature change of the temperature sensor 16 during the small current supply time T2, and starts supplying the large current. The time required to return to a temperature (voltage) higher than the detected temperature (voltage) by a certain temperature (voltage) is measured, and if the measured recovery time is shorter than a predetermined time, it is determined that there is hot and cold water in the heat exchanger 3 and measured. If the return time is longer than the predetermined time, it is determined that there is no hot or cold water in the heat exchanger 3.

In FIG. 5A, the temperature (voltage) detected by the temperature sensor 16 at the time when the temperature sensor 16 is energized at 100 milliamps for 3 seconds with hot water in the heat exchanger 3 is shown in FIG. It is clear that the temperature (voltage) is lower than the temperature (voltage) detected by the temperature sensor 16 after energizing under the same condition in the state where there is no hot water in the heat exchanger 3 in (b). Therefore, the hot water judging unit (not shown) measures the difference between the detected temperature (voltage) at the start of large current supply and the detected temperature (voltage) at the end of large current supply,
If the difference is small, it may be determined that there is hot water in the heat exchanger 3, and if the measured difference is large, it may be determined that there is no hot water in the heat exchanger 3. FIG. And a circuit diagram of a resistance value detection unit. The circuit diagram of FIG.
The difference from the circuit diagram of (b) is the resistance value detection unit C2.
In the circuit diagram of FIG. 4C, a current detection resistor 25 is connected in series with the temperature sensor 16, and a voltmeter 24 is connected in parallel to the current detection resistor 25. Although the present embodiment has been described using the temperature sensor 16, the same control may be performed using the temperature sensor 14 attached to the water passage 12a.

FIG. 6 is a diagram showing the overall configuration of a water heater provided with hot water detecting means A2 according to the third aspect of the present invention. By using the anti-freezing heater 26 and the temperature sensor 14 attached to the water passage 12a in the vicinity of the heater 15, an energizing section (not shown) for the anti-freezing heater 26 (not shown) and the temperature sensor 1 are provided.
4 and a hot water judging unit (not shown) for judging the presence or absence of hot water based on the detection result of the resistance detecting unit. In this embodiment, the anti-freezing heater 26 is energized by the energizing section,
The degree of increase in the temperature of the hot water in the water passage 12a due to the energization is detected by the resistance value detection unit, and the presence or absence of the hot water in the water passage 12a is determined by the hot water determination unit based on the detection result.
For example, the difference between the detected temperature of the temperature sensor 14 after energizing the freeze prevention heater 26 for a certain period of time and the detection temperature at the start of energization, that is, an increase in the detected temperature of the temperature sensor 14 before and after the energization of the freeze prevention heater 26 for a certain period of time. It is determined by the gradient. Further, as another example, the anti-freezing heater and the temperature sensor are connected to the anti-freezing heater attached to the tapping metal 28 fixed to the casing 27 of the water heater or the anti-freezing heater 29 attached to the water passage 12b near the tapping metal 28. The sensor 16 may be used instead. Further, as another embodiment, an antifreeze heater and a temperature sensor are attached to an outer wall surface of the heat exchanger 3 or an antifreeze heater attached to a water passage 12a wound around the outer wall surface of the heat exchanger 3. Heater and temperature sensor 14 or temperature sensor 16
Alternatively, a temperature sensor attached to the bend portion of the heat exchanger 3 can be used.

FIG. 7 is a sectional view of a main part of a water heater provided with the hot water detecting means A3 according to the fourth aspect of the present invention. The feature of the hot and cold water detecting means A3 is that a float type water level detector A33 is attached and the water level detector A3 is provided.
3 in that a hot water judging unit (not shown) for judging the presence or absence of hot water based on the detection result is provided. That is, in FIG.
Reference numeral 31 denotes a water supply fitting attached to the casing 27 of the water heater, and the water supply fitting 31 is connected to the external water supply pipe through the water passage 12.
a, in which a disc-shaped filter 32 is housed. A float 34 is integrally attached to the cylindrical filter body 33 to which the filter 32 is attached. When hot water is present in the water passage 12a, the upper end of the filter body 33 contacts the upper wall 35a of the filter chamber 5. A detector 37 such as a magnetic sensor performs a detection operation in response to a magnet 36 provided in the filter body 33. Conversely, when there is no hot or cold water in the water passage 12a, the filter body 33 descends the filter chamber 5 and its lower end abuts against a stopper 39 attached to the guide spindle 38 of the filter body 33, and the detector 37 detects the operation. do not do. Therefore, in the detection of hot water when the hot water is stopped, the hot water judging section judges whether there is no hot water or not depending on whether the detector 37 is in the detecting operation state.

FIG. 8 is a sectional view of a main part of a water heater provided with the hot water detecting means A4 according to the fifth aspect of the present invention. The feature of the hot water detecting means A4 is that an electrode type water level detector A44 is attached, and a hot water determining section (not shown) for determining the presence or absence of hot water based on the detection result of the water level detector A44 is provided. is there. In FIG. 8, reference numeral 40 denotes a water level detection electrode attached to the water passage 12a of the water heater. This electrode 40 is provided on the wall of the copper tube forming the water passage 12a.
Are fixed through the water passage 12a. On the other hand, the earth 42 is attached to the copper pipe wall forming the water passage 12a, and a power supply 43 and an ammeter 44 are connected in series between the water level detection electrode 40 and the earth 42. Water channel 12
When there is hot water in a, the ammeter 44 detects the energization when the switch 45 is turned on, and when there is no hot water in the water passage 12a, the ammeter 44 does not detect the energization even when the switch 45 is turned on. When the hot water is stopped, detection of hot water
5 is turned on, and the hot water judging section judges whether there is no hot water or not depending on whether the ammeter 44 detects the energization.

【The invention's effect】

As described above, the water heater of claim 1 is
The following effects are obtained. Before starting the heat retaining means after stopping hot water supply, the presence or absence of hot water in the heat exchanger is detected without performing combustion heating, and if there is no hot water in the heat exchanger, the operation of the heat retaining means is prohibited. As a result, there is no occurrence of an empty firing state of the heat exchanger, so that the durability of the heat exchanger is not adversely affected. In the water heater according to the second aspect, the presence or absence of hot water can be detected without adding a new member to the hot water detecting means and without heating the heat exchanger at all, so that the durability of the heat exchanger is adversely affected. In addition to not providing the water heater, the cost of the water heater is not increased, and the power consumption is sufficient for the self-heating of the temperature sensor, so that the running cost can be suppressed. Furthermore, in the water heater according to the third aspect, the presence or absence of hot water can be detected without adding a new member to the hot water detecting means and without heating the heat exchanger at all, which adversely affects the durability of the heat exchanger. In addition, there is no increase in the cost of the water heater. Claim 4
In the water heater according to the fifth aspect, since the durability of the heat exchanger is not adversely affected and the control configuration is not complicated, the cost of the water heater is not increased.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a water heater according to the present invention.

FIG. 2 is an explanatory diagram of hot water temperature control by a heat retaining means according to the embodiment of the water heater of the present invention.

FIG. 3 is a schematic flowchart of overall control according to the embodiment of the water heater of the present invention.

FIG. 4 is a circuit diagram of a current control unit and a resistance value detection unit of a temperature sensor which constitutes an embodiment of the hot and cold water detecting means according to the second aspect of the present invention.

FIG. 5 is an explanatory diagram showing a change of hot and cold water in the water passage by the hot and cold water detecting means according to the invention of claim 2;

FIG. 6 is an overall configuration diagram of a water heater provided with hot water detecting means according to the invention of claim 3;

FIG. 7 is a cross-sectional view of a main part of a water heater provided with hot water detecting means according to the invention of claim 4;

FIG. 8 is a sectional view of a main part of a water heater provided with the hot and cold water detecting means according to the invention of claim 5;

[Explanation of symbols]

 Reference Signs List 1 burner 2 combustion chamber 3 heat exchanger 4 fan 12a water passage 13b water passage 14 temperature sensor 16 temperature sensor A1 hot water detecting means B1 current control section C1 resistance value detecting section C2 resistance value detecting section A2 hot water detecting means A3 hot water detecting means A33 Water level detector A4 Hot water detector A44 Water level detector

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[Procedure amendment]

[Submission date] December 13, 1996

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 6

FIG. 2

FIG. 3

FIG. 7

FIG. 8

FIG. 4

FIG. 5

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Takeda 93, Edo-cho, Chuo-ku, Kobe, Hyogo Pref. In Noritz (72) Inventor Yutaka Nakamura 93 Edocho, Chuo-ku, Kobe, Hyogo Co., Ltd.Inside Noritz (72) Haruaki Mitsuda 93 Edocho, Chuo-ku, Kobe, Hyogo Co., Ltd. In Noritz (72) Inventor Tomohiro Nishihata 93 in Edo-cho, Chuo-ku, Kobe-shi, Hyogo

Claims (5)

[Claims] 1. A water heater comprising a burner, a heat exchanger, and a water passage interposed between the heat exchanger and a heat retaining means for intermittently heating the heat exchanger when the hot water is stopped. Hot water detecting means for detecting the presence or absence of hot water in the exchanger in a non-combustion state is provided, and when hot water is detected by the hot water detecting means, the warming means can be operated, and when hot water is not detected, the warming means is activated. A water heater characterized by comprising control means for inhibiting operation. 2. A temperature sensor attached to a water passage, a current control unit for varying a current supplied to the temperature sensor, and the temperature sensor when a large current is supplied to the temperature sensor or after a large current is supplied to the temperature sensor. 2. The water heater according to claim 1, comprising: a resistance value detecting section for detecting the resistance value of the hot water and a hot water judging section for judging presence or absence of hot water based on a detection result of the resistance value detecting section. 3. A hot-water detecting means for detecting a resistance value of a temperature sensor and an anti-freezing heater attached to a water passage, an energizing section for the anti-freezing heater, and a temperature sensor when energizing or after energizing the anti-freezing heater. 2. The water heater according to claim 1, comprising a resistance value detecting section for performing the operation and a hot water judging section for judging the presence or absence of hot water based on the detection result of the resistance value detecting section. 4. The hot water detecting means comprises a float type water level detector provided in the water passage and a hot water judging section for judging the presence or absence of hot water based on the detection result of the water level detector.
The water heater described. 5. The hot water supply according to claim 1, wherein the hot water detecting means comprises an electrode type water level detector disposed in the water passage and a hot water judging section for judging presence or absence of hot water based on a detection result of the water level detector. vessel.