JP3273005B2 - Water heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot water supply apparatus for supplying hot water to a bathtub or a kitchen.

[0002]

2. Description of the Related Art For example, in an instantaneous gas water heater, a heat exchanger which is heated by a gas burner and raises the temperature of water supplied from a water supply pipe, and a hot water supply from the heat exchanger via a water supply pipe. A hot water supply temperature sensor for detecting the temperature of hot water to be supplied;
And a running water sensor for detecting the presence or absence of running water passing through the heat exchanger.

[0003] In such a gas water heater, when water supply to the heat exchanger is detected by the flowing water sensor,
The heat exchanger is heated by the gas burner, and the hot water whose temperature has been raised when passing through the heat exchanger is discharged to the hot water supply pipe.

However, in this case, hot water is supplied from the end of the hot water supply pipe after the water staying in the heat exchanger and the hot water supply pipe is supplied. Therefore, there is a time delay before the hot water is actually supplied, and the usability is poor.

Therefore, in order to reduce such a time delay, a heat exchange temperature sensor for detecting the temperature of hot water near the outlet of the heat exchanger is provided, and even when hot water supply is stopped (when flowing water is not detected by the flowing water sensor). There has been known a gas hot water supply device which performs heat retention control for intermittently operating a gas burner so that the temperature detected by the heat exchange temperature sensor is maintained within a predetermined range (Japanese Patent Application Laid-Open No. 9-243169).

[0006] By performing the heat retention control in this manner, the amount of water to be supplied to the tip of the hot water supply pipe from the outlet of the heat exchanger to the tip of the hot water supply pipe before the hot water is actually supplied. Since only water can be used, the delay time can be reduced as compared with a case where the heat retention control is not performed.

By the way, when the gas burner is operated in a state where there is no water in the heat exchanger, that is, when performing so-called dry heating, the heat exchanger may be deteriorated or damaged. Therefore, water presence / absence detection means for detecting the presence / absence of water in the heat exchanger is provided, and when the presence / absence detection means detects that there is no water in the heat exchanger, execution of the heat retention control is prohibited, It is common practice to prevent the above-mentioned empty burning.

As a method for detecting the presence or absence of water, the rate of temperature rise of the thermosensitive resistor when the thermosensitive resistor is self-generated and the self-heating are stopped. A method is known which utilizes the fact that the rate of decrease in the temperature of the heat-sensitive resistor later differs between when the heat-sensitive resistor is in the air and when it is in the water (Japanese Patent Publication No. 7-89074).

However, the inventors of the present application have found that when the presence or absence of water in the heat exchanger is detected based on a change in temperature of the heat-sensitive resistance element when the heat-sensitive resistance element causes self-heating, Due to various external factors, even though water actually exists in the heat exchanger, it is erroneously detected that there is no water in the heat exchanger, and it is found that execution of the heat retention control may be prohibited. did.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hot water supply apparatus in which execution of heat keeping control is prevented from being prohibited due to erroneous detection of the presence or absence of water in a heat exchanger.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a heat exchanger for heating water supplied by a water supply pipe by a heating means, and hot water heated by the heat exchanger. A hot water supply pipe, a hot water supply temperature sensor for detecting a temperature of hot water supplied from the hot water supply pipe, a heat exchange temperature sensor for detecting a temperature of hot water near an outlet of the heat exchanger, and passing through the heat exchanger. A running water sensor for detecting the presence or absence of flowing water, and a water presence detection for applying a voltage to the thermosensitive resistor to such an extent that the thermosensitive resistor self-heats and judging from the temperature change whether or not the thermosensitive resistor is in water. A hot water supply control for adjusting a heating amount of the heating means so that a detected temperature of the hot water supply temperature sensor coincides with a predetermined hot water supply target temperature when flowing water is detected by the flowing water sensor; Running water is detected And when the presence or absence of water in the heat exchanger is detected by the water presence / absence detection means, and when the temperature detected by the heat exchange temperature sensor falls below a predetermined heat retention start temperature, the heating means And a hot-water supply control means for performing heat-retention control for operating for a heating time determined according to a predetermined heat-retention target temperature.

[0012] The degree of temperature rise of the heat-sensitive resistance element when the heat-sensitive resistance element self-heats is higher when the heat-sensitive resistance element is in the air than when the heat-sensitive resistance element is in the water. Also increases. This is because water has a higher heat radiation effect than air.

Therefore, based on such a difference in temperature change of the thermal resistance element, it is determined whether the thermal resistance element is in the air or not.
By determining whether or not there is water, it is possible to detect whether or not water is present at the place where the thermosensitive resistance element is installed.

However, due to various factors, the presence / absence of water may be detected by the presence / absence detection means while the temperature of the water in the heat exchanger is rising. The factors that increase the temperature of the water in the heat exchanger as described above include:
For example, an antifreeze heater provided to prevent freezing of water in the heat exchanger may be operating. In this case, the temperature of the water in the heat exchanger rises due to the operation of the antifreeze heater, and the temperature of the water in the heat exchanger stops increasing as the operation of the antifreeze heater stops.

Further, when the temperature of the water supply is lower than the outside temperature, such as when groundwater is supplied in summer, water is supplied from the hot water supply pipe in a water mode (a state in which the operation of the heating means is stopped). Immediately after, the temperature of the water in the heat exchanger rises because the low-temperature water staying in the heat exchanger after the supply of water is stopped is heated by the outside air. In this case,
As the time elapses, the temperature of the water in the heat exchanger becomes constant, and the temperature of the water stops increasing.

In the hot water supply apparatus for supplying hot water from the heat exchanger to the bathtub, a predetermined amount of water is supplied.
In a device having a so-called water supply function, if the execution of the water supply is instructed during the execution of the heat retention control and the operation of the heating means, the operation of the heating means is stopped.

Since the heating means is generally provided below the heat exchanger, when the operation of the heating means is stopped as described above, the water temperature is lower in the lower part than in the upper part of the heat exchanger. Is high. Therefore, when the execution of the water supply is erroneously instructed and the execution of the water supply is canceled immediately after the execution instruction, the convection in the heat exchanger causes the temperature of the water above the heat exchanger to rise. To rise. still,
In this case, the temperature of the water in the heat exchanger becomes uniform over time, and the rise in the temperature of the water in the heat exchanger stops.

When the temperature of the water in the heat exchanger is rising due to the factors described above, if the heat-sensitive resistance element causes self-heating, in addition to the rise in temperature due to self-heating, , The degree of increase in the temperature of the thermal resistance element may be as large as when the thermal resistance element is in the air.

In this case, the temperature change of the heat-sensitive resistance element is the same as when the heat-sensitive resistance element is in the air. Therefore, even though water is actually present in the heat exchanger, It is erroneously detected that there is no water, and the hot water supply control means prohibits the execution of the heat retention control.

Therefore, in the present invention, in order to prevent the execution of the heat retention control from being prohibited due to such erroneous detection of the presence or absence of water, in the water heater, the hot water supply control means executes the heat retention control. In this case, when the presence or absence of water is detected by the water presence / absence detection unit, the presence or absence of water is detected by the water presence / absence detection unit again after a first predetermined time has elapsed. I do.

According to this, when it is erroneously detected that there is no water despite the presence of water in the heat exchanger, after the erroneous detection,
When the above-mentioned factors are resolved during the elapse of the first predetermined time, after the elapse of the first predetermined time, the presence / absence of water in the heat exchanger is detected again by the water presence / absence detecting means. In addition, the presence of water can be correctly detected.
Accordingly, it is possible to prevent the execution of the heat retention control from being prohibited due to the erroneous detection of the presence or absence of water.

When the hot water supply control means detects that there is no water in the heat exchanger by the water presence / absence detection means, water is present in the heat exchanger for a second predetermined time. The detection of the presence or absence of water by the water presence / absence detecting means is repeated every time the first predetermined time elapses until the detection is made.

According to the present invention, the detection of the presence or absence of water is repeatedly performed until the second predetermined time elapses, so that the above-mentioned factors are eliminated and the temperature of the water in the heat exchanger rises. Even if the time until the stoppage exceeds the first predetermined time, it is possible to prevent the execution of the heat retention control from being prohibited due to the erroneous detection of the presence or absence of water.
Then, since the time limit of the second predetermined time is provided, the detection of the presence / absence of water is not repeated endlessly when there is no water in the heat exchanger, instead of erroneous detection.

[0024] When the hot water supply control means detects that there is no water in the heat exchanger by the water presence / absence detection means, the hot water supply control means determines that water is present in the heat exchanger up to a predetermined number of times. Until the detection, the detection of the presence or absence of water by the water presence / absence detecting means is repeated every time the first predetermined time elapses.

According to the present invention, the detection of the presence or absence of water is repeatedly performed until the predetermined number of times is reached, so that the above-described factors are eliminated and the rise of the temperature of the water in the heat exchanger is stopped. Even if the time exceeds the first predetermined time, it is possible to prevent the execution of the heat retention control from being prohibited due to the erroneous detection of the presence or absence of water. And
Since the predetermined number of times is provided, the detection of the presence or absence of water is not endlessly repeated when there is no water in the heat exchanger, rather than erroneous detection.

[0026]

FIG. 1 shows an example of an embodiment of the present invention.
This will be described with reference to FIGS. 1 is an overall configuration diagram of a hot water supply device of the present invention, FIG. 2 is an external view of a remote controller provided in the hot water supply device shown in FIG. 1, and FIG. 3 is a water presence / absence detecting means provided in the hot water supply device shown in FIG. FIG. 4 is an explanatory diagram of the operation of the water presence / absence detecting means shown in FIG. 3, and FIG. 5 is an operational explanatory diagram of the freeze prevention heater provided in the hot water supply device shown in FIG.

Referring to FIG. 1, a hot water supply apparatus 1 of the present embodiment includes a hot water supply section 2 and a reheating section 3, and a controller 4 controls the hot water section 2 and the reheating section 3. Has become.

The hot water supply unit 2 includes a hot water supply heat exchanger 6 (corresponding to a heat exchanger according to the present invention) which is heated by a hot water supply burner 5 (corresponding to a heating means according to the present invention) which is operated by a control signal from a controller 4. A water supply pipe 7 connected to a non-use water pipe to supply water to the hot water supply heat exchanger 6, a water quantity servo 8 for limiting the opening degree of the water supply pipe 7 based on a control signal from the controller 4, and a controller for detecting the temperature of supplied water. 4, a running water sensor 1 that detects the presence or absence of running water passing through the hot water supply heat exchanger 6 and outputs the running water to the controller 4.
0, a hot water supply pipe 11 from which hot water heated by the hot water supply heat exchanger 6 is supplied, a bypass pipe 12 for mixing a part of water supplied to the water supply pipe 7 into the hot water supply pipe 11, and a bypass by a control signal from the controller 4 A bypass servo 13 for adjusting the opening of the pipe 12; a controller 4 for detecting the temperature of hot water in a hot water supply pipe 25 downstream of a junction of the hot water supply pipe 11 and the bypass pipe 12;
And a heat exchange temperature sensor 15 that detects the temperature of the hot water near the outlet of the hot water supply heat exchanger 6 and outputs the detected temperature to the controller 4.

A gas supply pipe 16 for supplying a fuel gas to the hot water supply burner 5 has a source gas solenoid valve 17 opened and closed by a control signal from the controller 4, and hot water supply gas solenoid valves 18, 19; Is provided with a hot water supply gas proportional valve 20 whose opening is adjusted by the control signal.

Reference numeral 21 denotes a hot water supply combustion fan for supplying combustion air to the hot water supply burner 5, and its rotation speed is varied by a control signal from the controller 4. Reference numeral 22 denotes a hot water supply ignition plug that receives a high voltage through an igniter 23 in response to a control signal from the controller 4 and ignites the hot water supply burner 5. Reference numeral 24 denotes a hot water supply that detects the combustion state of the hot water supply burner 5 and outputs it to the controller 4. It is a frame rod. 27
When the pressure in the hot water supply heat exchanger 6 rises, the valve is opened to release excess pressure, and the hot water supply heat exchanger 6 and the hot water supply pipe 11 are opened.
It is an overpressure safety valve and a water tap for draining water from inside. The overpressure safety valve / water tap 27 is attached to the lower surface of the water heater main body.

On the other hand, the reheating unit 3 includes a bath heat exchanger 41 heated by a bath burner 40 operated by a control signal from the controller 4, and a hot water in a bathtub 42 circulated by a control signal from the controller 4. Bath heat exchanger 4
1, a circulation pump 44, a bath temperature sensor 45 that detects the temperature of hot water in the bathtub 42 and outputs it to the controller 4, and a water flow that detects the presence or absence of a water flow in the circulation path 43 and outputs it to the controller 4. A switch 46 is provided.

A gas supply pipe 16 for supplying a fuel gas to the bath burner 40 has a bath gas solenoid valve 47 which is opened and closed by a control signal from the controller 4 and a gas governor for maintaining a constant fuel gas supply amount. 48 are provided.

Reference numeral 49 denotes a bath combustion fan for supplying combustion air to the bath burner 40, the rotation speed of which is varied by a control signal from the controller 4. Reference numeral 50 denotes a bath ignition plug to which a high voltage is applied from the igniter 23 according to a control signal from the controller 4 to ignite the bath burner 41. Reference numeral 51 denotes a bath frame rod for detecting the combustion state of the bath burner and outputting the detected state to the controller 4.

The circulation path 43 is connected to the hot water supply pipe 25 via a pouring solenoid valve 52, a bath hot water supply pipe 53, and a three-way valve 54 which are opened and closed by a control signal from the controller 4. Thereby, hot water is supplied from hot water supply unit 2 to bathtub 42 by opening pouring electromagnetic valve 52. Reference numeral 56 denotes a flow rate sensor that detects the flow rate of hot water supplied to the bathtub 42 and outputs the same to the controller 4. Reference numeral 57 denotes a water level sensor that detects the level of hot water in the bathtub 42 using hydrostatic pressure and outputs the same to the controller 4.

The controller 4 includes hot water supply control means 31, additional heating control means 32, and water presence / absence detection means 58.
The remote controller 3 includes a CPU, a ROM, a RAM, and the like.
Hot water supply unit 2 according to various operation modes indicated by 0
And the reheating unit 3 is controlled.

Next, referring to FIG.
An operation switch 60 for instructing an operation start and an operation stop of the entire hot water supply apparatus 1, and a predetermined amount of hot water supplied to the bathtub 42;
An automatic switch 61 for instructing the start of automatic operation for performing additional heating up to a predetermined boiling temperature after the hot water supply, and a hot water supply pipe 25;
Hot water supply temperature switch 62 for setting a target temperature (corresponding to the hot water supply target temperature of the present invention), and a clock setting switch 63 for specifying a clock time setting mode for setting the time of a built-in clock.
A reservation setting switch 64 for specifying a reservation time setting mode for setting a reservation time for the automatic operation; a time setting switch 65 and a minute setting switch 66 for setting each time in the clock time setting mode and the reservation time setting mode. And a reservation operation switch 67 for setting the reservation of the automatic operation.
And a heat keeping switch 68 for instructing execution of a heat keeping operation for keeping the temperature of hot water in the hot water supply heat exchanger 6 within a predetermined range, and a display unit 69 for displaying hot water supply temperature and time.

The user operates the operation switch 6 of the remote controller 30.
When 0 is operated, the entire hot-water supply apparatus 1 enters the operation standby state, and the operation lamp 70 incorporated in the operation switch 60 is turned on. In this state, when the user opens the callan 26 connected to the tip of the hot water supply pipe 25, water supply to the water supply pipe 7 is started, and the flowing water sensor 10 detects flowing water. The controller 4 controls the water supply pipe 7 based on the output from the running water sensor 10.
When the start of water supply is recognized, the hot water supply combustion fan 21 is operated, the original gas solenoid valve 17, the hot water supply gas proportional valve 20, the hot water supply gas electromagnetic valves 18 and 19 are opened, and a high voltage is applied to the igniter 23. Thus, a spark discharge is generated in the hot water supply ignition plug 22 to perform the ignition processing of the hot water supply burner 5.

When the hot water supply control means 31 provided in the controller 4 recognizes from the output of the hot water supply frame rod 24 that the hot water supply burner 5 has been ignited, the detected temperature of the hot water supply temperature sensor 14 and the remote control 30 are used. The hot water gas proportional valve 20 is adjusted so that the set hot water supply target temperature matches.
Hot water supply control is performed to adjust the opening degree of the hot water supply combustion fan 21, the opening and closing of the hot water supply gas solenoid valves 18 and 19, the opening degree of the water volume servo 8, and the opening degree of the bypass servo 13. As a result, hot water at the temperature set by the user is supplied from the curan 26.

When the user operates the automatic switch 61 of the remote controller 30, the controller 4 starts the above-described automatic operation, and opens the pouring solenoid valve 52 first. By opening the pouring solenoid valve 52, water supply to the water supply pipe 7 is started,
The hot water supply burner 5 is ignited in the same manner as when the user opens the curran 26 described above, and the hot water supply pipe 11 is used to supply the hot water supply electromagnetic valve 52, the bath hot water supply pipe 53, the three-way valve 54, and the
The hot water supply at the hot water supply target temperature is started via 3.

The controller 4 accumulates the amount of hot water supplied to the bathtub 42 based on the output from the flow rate sensor 56, and closes the pouring solenoid valve 52 when the accumulated value reaches the filling level.
The supply of a predetermined amount of hot water (hot water) to the bathtub 42 ends.

After filling the bathtub 42, the controller 4 detects the temperature of the hot water in the bathtub 42 based on the output of the bath temperature sensor 45. If the detected temperature is lower than the boiling temperature, the controller 4 determines the temperature of the boiling water. Until the hot water in the bathtub 42 is heated.

In order to raise the temperature, the additional heating control means 32 provided in the controller 4 activates the bath pump 44 to circulate the hot water in the bathtub 42 through the circulation path 43 and to heat the bath combustion fan 49. Is operated, the original gas solenoid valve 17 and the bath gas solenoid valve 47 are opened, a high voltage is applied to the bath ignition plug 50 via the igniter 23 to generate spark discharge, and the bath burner 40 is ignited. .

When the additional heating control means 32 recognizes from the output of the bath frame rod 51 that the bath burner 40 has been ignited, the temperature detected by the bath temperature sensor 45 reaches the boiling temperature. Until the above, the combustion of the bath burner 40 is continued. Thereby, the temperature of the hot water in the bathtub 42 is raised to the boiling temperature.

Note that the additional heating control means 32 keeps the temperature of the hot water in the bathtub 42 substantially at the boiling temperature for four hours after the hot water in the bathtub 42 reaches the boiling temperature. Thus, the bath heat keeping operation of intermittently burning the bath burner 40 is performed. Then, during the bath heat keeping operation, the heat keeping mark 72 is displayed on the display section 69 of the remote controller 30.

When the user operates the automatic switch 61 of the remote controller 30 and recognizes from the output of the water level sensor 57 that the bathtub 42 has already been filled with water, the controller 4 sets the bathtub to the bathtub state. 42 is not filled, but only additional heating up to the above-mentioned boiling temperature is performed.

When the user operates the reservation operation switch 67, the reservation operation is set, and the reservation mark 71 is displayed on the display section 69 of the remote controller 30. The reservation setting switch 64, the hour switch 65, and the minute switch 6
The automatic operation described above is executed when the preset reservation time is reached in 6.

When the user operates the water supply switch 75, the hot water supply control means 31 executes a so-called water supply, which supplies a predetermined amount (for example, 10 liters) of water to the bathtub 42. The water is for lowering the temperature of the hot water in the bathtub 42 when the temperature is too high.

Hot water supply control means 31 starts pouring water by opening pouring valve 52 with the operation of hot water supply burner 5 stopped. As a result, the water supplied from the water supply pipe 16 is directly (without being heated) the hot water supply heat exchanger 6, the hot water supply pipe 1
1, the hot water is supplied to the bathtub 42 via the hot water supply pipe 25 and the circulation path 53. Then, the hot water supply control means 31 calculates an accumulated water supply value from the amount of water supplied to the bathtub 42 detected by the flow sensor 56, and when the accumulated water supply value reaches the predetermined amount (10 liters), the pouring valve 52. Is closed to finish watering.

Next, when the user operates the heat retention switch 68, the hot water supply control means 31 sets the temperature of the hot water in the hot water supply heat exchanger 6 to a predetermined temperature range for a predetermined heat retention time (for example, one hour). Execute the heat retention control to keep it within. This heat retention control
This is a process for reducing the time (delay time) from when the user opens the curan 26 to when water is actually supplied to the curan 26.

As described above, the hot water supply burner 5 is normally ignited when the flowing water sensor 10 recognizes that water supply to the heat exchanger 6 has started. At this time, water remains in the hot water supply pipe 25, the hot water supply pipe 11, and the heat exchanger 6. Therefore, the hot water is supplied from the curan 26 after the water staying in the hot water supply pipe 25, the hot water supply pipe 11, and the heat exchanger 6 is supplied. In addition, hot water supply heat exchanger 6
The length of the inner pipe is, for example, 2.5 m.

Therefore, by keeping the hot water in the hot water supply heat exchanger 6 in advance, the amount of water to be supplied before the hot water supply is started can be reduced to only the amount of water retained in the hot water supply pipe 25 and the hot water supply pipe 11. The delay time from when the user opens the curran 26 to when the hot water supply is actually started can be reduced.

Here, the above-mentioned heat retention control is executed in a state where no water remains in the hot water supply heat exchanger 6 such as after draining water, and the hot water supply burner 5 is burned. The exchanger 6 may be deteriorated or damaged. Therefore, the hot water supply control means 31 detects the presence or absence of water in the hot water supply heat exchanger 6 by the water presence / absence detection means 58 when executing the heat retention control, and only when it detects the presence of water, does the hot water supply burner 5. I'm trying to burn.

Next, the operation of the water presence / absence detecting means 58 will be described with reference to FIGS. FIG. 3 is a block diagram of the water presence / absence detecting means 58. In the present embodiment,
A thermistor is used for the heat exchange temperature sensor 15, and the heat exchange temperature sensor 15 is diverted as a heat-sensitive resistance element for detecting the presence or absence of water.
Therefore, the water presence / absence detecting means 58 has two functions of detecting the temperature near the outlet of the hot water supply heat exchanger 6 and detecting the presence / absence of water in the hot water supply heat exchanger 6.

Referring to FIG. 3, water detecting means 58 includes
A / D conversion circuit 80, CPU 81, ROM 82, RAM
83, switching circuit 84, 24V power supply 85, 5V power supply 86,
The CPU 81 detects the temperature of hot water near the outlet of the hot water supply heat exchanger 6, and
The voltage applied to the thermistor 15 is switched by the switching circuit 84 when detecting the presence or absence of water in the hot water supply heat exchanger 6.

When detecting the temperature near the outlet of the hot water supply heat exchanger 6, the CPU 81 applies the supply voltage from the 5 V power supply 86 to the thermistor 15, and outputs the voltage drop at the thermistor 15 to the A / D conversion circuit 80. Captured as digital values through Then, the CPU 81 calculates the resistance value of the thermistor 15 based on the voltage drop and obtains the temperature corresponding to the resistance value from a data table stored in the ROM 22 in advance, so that the vicinity of the outlet of the hot water supply heat exchanger 6 is obtained. Detect the temperature of hot water.

On the other hand, when detecting the presence or absence of water in the hot water supply heat exchanger 6, the CPU 81 applies a supply voltage from the 24 V power supply 85 to the thermistor 15. The voltage of 24 V is a voltage at which the thermistor 15 generates heat by itself, and the temperature of the thermistor 15 increases due to the self-heating.

FIG. 4 shows that the thermistor 15
5 is a graph showing a transition of the temperature of the thermistor 15 when a voltage of V is applied. In FIG. 4, a change in the temperature when the thermistor 15 is in the air, and a change in the temperature when the thermistor 15 is in the water.

Is compared with the thermistor 15,
Immediately after application of a voltage of 4V, increasing the degree of temperature of the thermistor 15 is no difference out with (period in the figure E _1), rise in the temperature of the subsequent thermistor 15,
(When the thermistor 15 is in the air) is larger than (when the thermistor 15 is in the water).

When 30 seconds have elapsed since the start of the application of the 24 V voltage, the CPU 81 switches the voltage applied to the thermistor 15 to 5 V by the switching circuit 84. As a result, the self-heating of the thermistor 15 stops, and the temperature of the thermistor 15 decreases. Here, the thermistor 15 immediately after switching the voltage applied to the thermistor 15 from 24 V to 5 V is used.
Width reduction in temperature (figure T _dw) has no difference out with (period in the figure E _2).

As described above, in the overall temperature transition,
Figure only a voltage upon application after a lapse of E _1, the difference appears in Toto. That is, the temperature T ₀ of the thermistor 15 immediately before the application of the 24 V voltage to the thermistor 15 and the temperature T ₁ of the thermistor 15 at the time when E ₂ (one second) elapses after the application of the 24 V voltage is stopped 15 is in the air) and T ₂ (when the thermistor 15 is in the water) is ΔT when in the air: ΔT = T ₁ −T ₀ ≒ 11.7 ° C. When in the water, ΔT = T ₂ −T ₀ ≒ 1 ° C., which is larger in the air than in the water.

Therefore, the CPU 81 determines the temperature of the thermistor 15 immediately before the application of the 24 V voltage to the thermistor 15 and one second after the stop of the application of the 24 V voltage to the voltage drop at the thermistor 15 as described above. The detection is performed by taking in the data via a / D conversion circuit, and the ΔT is calculated.
Then, the calculated ΔT is set to a predetermined reference value T _B (for example, 3
° C.) as compared to, [Delta] T> T _B If the thermistor 15 is determined to waterless state in the air, [Delta] T ≦ T _B if the thermistor 15 is determined to water there state in water.

When the water presence / absence detecting means 58 determines that there is no water in the hot water supply heat exchanger 6, the hot water supply control means 31 prohibits the execution of the heat retention control and the hot water supply heat exchanger 6 becomes empty. Prevents burning.

Next, when the water staying in the hot water supply heat exchanger 6 freezes, the water pipe of the hot water supply heat exchanger 6 may be expanded and damaged. Therefore, referring to FIG. 5, in order to prevent such breakage of hot water supply heat exchanger 6 due to freezing, in hot water supply apparatus 1 of the present embodiment, a water supply pipe to hot water supply heat exchanger 6 is provided. An anti-freezing heater 90 is attached.

The anti-freezing heater 90 is connected to an AC power supply 92 (AC 100 V) via a bimetal switch 91 installed on the lower surface of the water heater main body. The bimetal switch 91 is turned on (contact closed) when the ambient temperature becomes 3.5 degrees or less, and turned off (contact opened) when the ambient temperature becomes 11.5 degrees or more after being turned on. )
It is set to be in the state.

As a result, when the ambient temperature of the bimetal switch 91 drops below 3.5 ° C.,
Starts to operate, and the water in the hot water supply heat exchanger 6 is heated until the ambient temperature becomes 11.5 degrees or more. This prevents the water staying in the hot water supply heat exchanger 6 from freezing.

Here, during the operation of the anti-freezing heater 90, the temperature of the thermistor 15 rises in accordance with the rise in the temperature of the water in the hot water supply heat exchanger 6. Therefore, the anti-freezing heater 90
When the presence or absence of water in the hot water supply heat exchanger 6 is detected during the operation, the temperature rise of the thermistor 15 due to the self-heating of the thermistor 15 is added to the temperature rise due to the operation of the freeze prevention heater 90. Therefore, the temperature rise of the thermistor 15 increases.

When the temperature rise of the thermistor 15 becomes substantially the same as that shown in FIG. 5, although there is actually water in the hot water supply heat exchanger 6, Is falsely detected as having no water.

Therefore, when the hot water supply control means 31 detects that there is no water in the hot water supply heat exchanger 6 by the water presence / absence detection means 58 when performing the heat retention control,
After the lapse of a predetermined time (corresponding to the first predetermined time of the present invention), the detection of the presence or absence of water is repeatedly executed during the warming time (for example, one hour, corresponding to the second predetermined time of the present invention). .

As described above, if the operation of the anti-freezing heater 90 is stopped while the detection of the presence or absence of water is repeatedly executed every time the predetermined time elapses, when the detection of the presence or absence of water is performed next, Since the rise of the temperature of the water in the hot water supply heat exchanger 6 due to the operation of the heater 90 is stopped, the presence of water in the hot water supply heat exchanger 6 is normally detected, and the heat retention control is executed. This prevents the execution of the heat retention control from being prohibited due to erroneous detection of the presence or absence of water.

As described above, the cause of the rise in the temperature of the water in the hot water supply heat exchanger 6 is that the freeze prevention heater 90
In addition, the operation of the water heater 1 was stopped in a situation where the water supply temperature was considerably lower than the ambient temperature of the hot water supply heat exchanger 6, such as when groundwater was supplied to the water supply pipe 7 in the summer. In this state, the user may open the curran 26 and use water.

In this case, when the user closes the curan 26, the low-temperature water staying in the hot-water supply heat exchanger 6 is heated by the outside air, so that the hot-water supply The temperature of the hot water in the exchanger 6 rises. Therefore, when the above-described detection of the presence or absence of water is performed in this state, it is determined that there is no water in spite of the fact that there is actually water in the hot water supply heat exchanger 6 as in the case where the freeze prevention heater 90 is operating. There is a risk of erroneous detection.

In this case, the temperature of the water in the hot water supply heat exchanger 6 and the outside air temperature are balanced with the lapse of time, and the rise in the temperature of the water in the hot water supply heat exchanger 6 stops. Therefore, as described above, by repeatedly performing the detection of the presence or absence of water every time the predetermined time elapses, it is possible to prevent the execution of the heat retention control from being prohibited due to the erroneous detection of the presence or absence of water.

When the user operates the water supply switch 75 of the remote controller 30 during the execution of the heat retention control, the hot water supply control means 31 stops the combustion of the hot water supply burner 5 and suspends the heat retention control. Is executed with priority. On the other hand, when the heat retention control is being performed and the hot water supply burner 5 is burning, the combustion control user erroneously operates the water supply switch 75 and immediately operates the water supply switch 75 immediately after the operation. When the execution of the water supply is canceled, the temperature of the hot water in the hot water supply heat exchanger 6 is higher in the lower part near the hot water supply burner 5 than in the upper part.

Therefore, also in this case, the hot water supply heat exchanger 6
Due to the convection of the hot water from the lower part to the upper part in the inside, the ambient temperature of the heat exchange temperature sensor 15 rises. Further, even when water has already flowed into the hot water supply heat exchanger 6 when the execution of the water supply is canceled by the operation of the water supply switch 75, heat is generated by the residual heat of the hot water supply heat exchanger 6. The ambient temperature of the interchange temperature sensor 15 may increase. When the above-described detection of the presence or absence of water is performed in such a state, it is erroneously determined that there is no water in spite of the fact that there is water in the hot water supply heat exchanger 6 as in the case where the freeze prevention heater 90 is operating. May be detected.

The rise in the temperature detected by the heat exchange temperature sensor 15 due to the execution of the water supply causes the temperature of the hot water to increase due to the convection and replacement of the hot water in the hot water supply heat exchanger 6 with the passage of time. Stop when uniform. Therefore, as described above, by repeatedly performing the detection of the presence or absence of water every time the predetermined time elapses, it is possible to prevent the execution of the heat retention control from being prohibited due to the erroneous detection of the presence or absence of water.

Further, even when the temperature of the water in the hot water supply heat exchanger 6 rises due to factors other than the factors described above and a situation where erroneous detection of the presence or absence of water occurs is detected, the detection of the presence or absence of the above-described water is also performed. When the cause is eliminated during the repetitive execution, the presence of water in the hot water supply heat exchanger 6 is normally detected, and the execution of the heat retention control is prohibited by erroneous detection of the presence or absence of water. Can be prevented.

In the present embodiment, the detection of the presence or absence of water is repeated when it is detected that there is no water in the hot water supply heat exchanger 6 until the heat retention time has elapsed. The detection of the presence / absence of water may be repeatedly performed with the limit as a limit.

Further, in the present embodiment, the hot water supply device using a gas burner as the heating means has been described, but the present invention is also applicable to a hot water supply device using a kerosene burner, an electric heater, or the like as a heating means. .

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a hot water supply device of the present invention.

FIG. 2 is an external view of a remote controller provided in the water heater shown in FIG.

FIG. 3 is a block diagram of a water presence / absence detection means.

FIG. 4 is a diagram illustrating the operation of a water presence / absence detection means.

FIG. 5 is an explanatory diagram of the operation of the freeze prevention heater.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Hot water supply apparatus, 2 ... Hot water supply part, 3 ... Additional heating part, 4 ... Controller, 5 ... Hot water supply burner, 6 ... Hot water supply heat exchanger, 7 ... Water supply pipe, 8 ... Water quantity servo, 9 ... Water supply temperature sensor, 10 ... Flowing water sensor, 11 hot water supply pipe, 12 bypass pipe, 13 bypass servo, 14 hot water temperature sensor, 15 heat exchange temperature sensor (thermistor), 16 gas supply pipe, 17 original gas solenoid valve, 18, 19 ... hot water supply gas solenoid valve, 20 ... hot water supply gas proportional valve, 21 ... hot water supply combustion fan, 22 ... hot water supply ignition plug, 23 ... igniter, 24 ... hot water supply frame rod, 2
5 ... Hot water supply pipe, 26 ... Caran, 27 ... Overpressure safety valve and water tap, 30 ... Remote control, 31 ... Hot water supply control means, 32 ... Additional heating control means, 40 ... Bath burner, 41 ... Bath heat exchanger
42 ... bathtub, 43 ... circulation path, 44 ... circulation pump, 45 ...
Bath temperature sensor, 46 ... water flow switch, 47 ... bath gas solenoid valve, 48 ... bath gas governor, 49 ... bath combustion fan, 50 ... bath spark plug, 51 ... bath frame rod, 52 ... pouring solenoid valve, 53 ... bath hot water supply Pipe, 54 ... three-way valve, 56 ... flow rate sensor, 57 ... water level sensor, 58 ... water presence / absence detection means

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F24H 1/10 303 F24H 1/10 302

Claims (3)

(57) [Claims] 1. A heat exchanger for heating water supplied by a water supply pipe by a heating means, a hot water supply pipe from which hot water heated by the heat exchanger is discharged, and a temperature of hot water supplied from the hot water supply pipe. A hot water supply temperature sensor for detecting the temperature of hot water near the outlet of the heat exchanger, a flowing water sensor for detecting the presence or absence of flowing water passing through the heat exchanger, and a heat-sensitive resistance element. A water presence / absence detecting means for applying a voltage at which the heat-sensitive resistance element self-heats and judging from the temperature change whether or not the heat-sensitive resistance element is in water, and when running water is detected by the running water sensor. Hot water supply control for adjusting the amount of heating of the heating means so that the detection temperature of the hot water supply temperature sensor matches a predetermined hot water supply target temperature, and no running water is detected by the running water sensor, and The heat exchanger When the presence of water is detected, when the temperature detected by the heat exchange temperature sensor falls below a predetermined heat retention start temperature, the heating means determines the heating time according to a predetermined heat retention target temperature. And a hot water supply control means for performing a heat retention control to be operated during the hot water supply, wherein the hot water supply control means, when executing the heat retention control, causes the water presence / absence detection means to supply water into the heat exchanger. When it is detected that there is no water, after the first predetermined time elapses, the presence or absence of water is detected again by the water presence / absence detecting means. 2. The hot water supply control means, when the water presence / absence detection means detects that there is no water in the heat exchanger, water is present in the heat exchanger for a second predetermined time. The hot water supply apparatus according to claim 1, wherein the detection of the presence or absence of water by the water presence / absence detection means is repeated each time the first predetermined time elapses until the detection is made. 3. The hot water supply control means, when the water presence / absence detection means detects that there is no water in the heat exchanger, determines that water is present in the heat exchanger up to a predetermined number of times. Until it is detected, every time the first predetermined time elapses,
The hot water supply apparatus according to claim 1, wherein the detection of the presence or absence of water by the water presence / absence detection means is repeatedly performed.