JP3091809B2 - Bath kettle with 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 bathtub equipped with a water heater which can supply hot water heated by a water heater to a bathtub and circulate the hot water in the bathtub to reheat it. The present invention relates to a bathtub with a water heater that automatically calculates and supplies insufficient hot water so that a bathtub has a desired amount of hot water.

[0002]

2. Description of the Related Art Conventionally, a circulating heating circuit for forcibly circulating water in a bathtub by a pump and heating by a heat exchanger provided in the middle of a circulation pipe line, and another heat exchanger taken in from a water supply system or the like. A bath kettle with a water heater is used which has a hot water supply circuit for supplying heated water to a bathtub through a circulation circuit. This type of bath water heater is equipped with a water level sensor for pouring water to a predetermined water level (so-called full-auto type), or a type that always supplies a predetermined amount of water without a water level sensor (so-called (Semi-auto type) and the like are known. However, in the latter semi-auto type, if the automatic switch is operated in a state where there is remaining hot water in the bathtub, the water level exceeds a predetermined level. Therefore, in order to detect the amount of hot water, an additional hot water is heated before the start of pouring, the amount of hot water is calculated from the temperature rise at that time, and an insufficient amount of hot water is automatically supplied to make the desired level of water. Some have.

An example of such control is disclosed in Japanese Patent Application Laid-Open No.
JP-A No. 1-15047 can be used. The control method disclosed in the same publication, the remaining hot water is heated for a certain time, the remaining hot water amount is calculated from the temperature rise at that time,
The main point is to determine the hot water supply amount to the bathtub based on the calculated value.

[0004]

However, the conventional water heater control disclosed in the above publication has the following problems. That is, in the water heater control disclosed in the above publication, the amount of heat supplied after heating for a certain period of time is basically divided by the temperature rise at that time to calculate the remaining amount of hot water. Even considering the heat efficiency of the heat exchanger, it does not take into account that there is heat radiation in each part such as piping and bathtub. If this amount of heat radiation is always constant, it is sufficient to consider the heat efficiency of the heat exchanger, but in practice, even the same type of bath varies depending on the piping length etc. according to the installation situation, and furthermore, the same bath Even the kettle varies depending on the water temperature and outside temperature. What is particularly problematic is that since the outside air temperature differs by more than 20 ° C. depending on the season, the amount of heat radiation greatly differs between winter and summer, and the effect cannot be ignored.

[0005] For example, in summer, the outside air temperature may be close to 30 ° C, in which case the difference between the hot water temperature and the outside air temperature is only about 10 ° C. Therefore, the amount of heat radiation is small, and most of the amount of heat supplied from the burner is used for raising the water temperature. For this reason, the temperature rise of the water temperature is large and the remaining hot water amount is calculated to be small, so that a large amount of hot water is supplied. On the other hand, during the winter nights,
The outside air temperature drops to about 0 ° C., and in that case, the difference between the hot water temperature and the outside air temperature approaches nearly 40 ° C., and the amount of heat radiation is large. Therefore, even if the amount of heat supplied from the burner is the same, the increase in water temperature is smaller than in summer, and as a result, the amount of remaining hot water is calculated to be considerably larger than the actual amount, so that the amount of hot water supplied becomes too small. In other words, there is a tendency for hot water to run short in winter when a sufficient amount of hot water is required.

The present invention solves the above-mentioned problems of the prior art, and calculates the amount of remaining hot water without being affected by the outside air temperature by taking into account heat radiation from pipes and bathtubs. It is an object of the present invention to provide a bath kettle with a water heater that can accurately determine a hot water supply amount and supply an appropriate hot water.

[0007]

In order to achieve this object, a bath kettle with a water heater according to the present invention comprises a hot water supply means for supplying hot water to a bath tub, a circulating heating means for circulating and heating the hot water in the bath tub, Hot water temperature detecting means for detecting the temperature of hot water, and heating control means for instructing the circulating heating means to perform circulating heating until the hot water temperature detected by the hot water temperature detecting means reaches a set temperature. Hot water presence / absence determining means for determining the presence / absence of hot water in the bathtub, and when the hot water presence / absence determining means determines that there is no hot water in the bathtub, a predetermined amount of hot water having a temperature slightly lower than the set temperature is supplied to the bathtub. First hot water supply command means for instructing the hot water supply means, and circulating heating of the hot water supplied by the first hot water supply command means to the set temperature by the circulating heating means. Heat dissipation to calculate heat Calculating means, and when the remaining hot water presence / absence determining means determines that there is hot water in the bathtub, the hot water is circulated and heated to the set temperature by the circulating heating means. The remaining hot water amount calculating means for calculating the remaining hot water amount in consideration of the discharged heat amount, and second hot water supply instruction means for automatically adding the insufficient hot water amount by the hot water supply means based on the calculation result of the remaining hot water amount calculating means. It is an abstract.

[0008] Here, the heat radiation amount calculating means, when supplying a predetermined amount of hot water to the empty bath, when circulating heating up to the set temperature, W = INP × η × t1-Qs × (T2-T1 ) (INP is the gas input amount, η is the thermal efficiency, t1 is the heating time, Qs is the set hot water amount, and T2-T1 is the temperature rise of circulating heating). In addition, the remaining hot water amount calculation means performs Q = (INP × η × t3−W3) / (T4−T3) (INP is a gas input) when circulating heating to a set temperature when there is remaining hot water in the bathtub. Quantity, η is thermal efficiency, t3 is heating time, W3 is heat release, T4-T3 is temperature rise of circulation heating)
The remaining hot water amount Q is calculated by the following equation.

[0009]

In the bath kettle with the water heater of the present invention having the above-described structure, first, the presence / absence of hot water in the bathtub is determined by the hot water presence / absence determining means. When there is no remaining hot water in the bathtub, the hot water supply means supplies a predetermined amount of hot water at a temperature slightly lower than the set temperature by the instruction of the first hot water supply instruction means, and the hot water is circulated for a certain time. Then, the hot water temperature detecting means detects the temperature of the hot water, the circulation heating means reheats the hot water to the set temperature according to a command of the heating control means, circulates the hot water for a predetermined time, and the hot water temperature detecting means detects the hot water temperature. Detect again. Based on the time required for the additional heating, the circulation time after the additional heating, the initial temperature of the hot water and the temperature after the circulation, the heat radiation amount calculating means calculates the heat radiation amount affected by the outside air temperature.

When there is remaining hot water in the bathtub, the remaining hot water temperature detecting means detects the temperature of the remaining hot water, the circulating heating means reheats the remaining hot water to a set temperature, and further circulates the remaining hot water for a predetermined time. Then, the hot water temperature detecting means detects the temperature of the remaining hot water again. From the time required for reheating at this time, the circulation time after reheating, the initial temperature of the remaining hot water and the temperature after circulation, and the heat release amount previously calculated by the heat release amount calculation means, the remaining hot water amount calculation means The amount of hot water in the bathtub is calculated, and if there is a shortage, the hot water supply means automatically supplies the shortage according to a command from the second hot water supply command means.

Here, in the bath kettle with a water heater according to the second aspect of the present invention, the heat radiation amount calculating means includes the gas input amount I
From the NP, the thermal efficiency η, the heating time t1, the set hot water amount Qs, and the temperature rise T2-T1 of the circulation heating, the heat radiation amount W is calculated by the following equation: W = INP x η x t1-Qs x (T2-T1). Further, in the bath kettle with a water heater according to the third aspect of the present invention, the remaining hot water amount calculating means obtains the following formula from the gas input amount INP, the thermal efficiency η, the heating time t3, the heat release amount W3, and the temperature rise T4−T3 of the circulation heating. The remaining hot water amount Q is calculated by the following formula: INP × η × t3−W3) / (T4−T3).

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A bath kettle with a water heater according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall configuration of a bath kettle with a water heater. The bath kettle 1 includes a circulating heating unit 10 for circulating and heating water in the bathtub 2, and hot water obtained by heating tap water or the like by gas combustion via the circulating heating unit 10.
And a controller 50 for controlling these operations.

The hot water supply unit 30 includes a water supply passage 31 to which cold water such as tap water is supplied, and a heat exchanger 3 connected to the water supply passage 31.
2 and a tapping channel 33 connected downstream of the heat exchanger 32
And a hot water supply path 34 and a general hot water supply path 35 provided by branching the hot water supply path 33 at the point A to form a flow path. Water supply channel 31
Is provided with a flow rate sensor 36 for detecting a flow rate and a thermistor 37 for detecting an incoming water temperature, and a tapping path 33 is provided with a thermistor 39 for detecting a tapping temperature.

A burner 40 is provided below the heat exchanger 32, and a gas conduit 41 is provided with a main solenoid valve 42 for opening and closing a gas flow path and a proportional control valve 43 for adjusting a gas flow rate. Bath hot water supply channel 34 branched off from hot water supply channel 33
Is a water supply valve 44 for opening and closing, a flow rate sensor 45 for detecting a flow rate of hot water to the bathtub 2, a cutoff valve 46, and a check valve 4 for preventing a backflow from the circulation heating unit 10 to the hot water supply unit 30.
7 and is connected to the circulation heating unit 10 at a point B. On the other hand, an external hot water supply pipe 4 leading to a hot water tap 5 such as a washroom or a shower is connected to a general hot water supply path 35 branched from the hot water supply path 33.

The circulating heating unit 10 includes a kettle circulating path 11 for circulating water in the bathtub 2 forming a flow path.
The heat exchanger 13 is heated by the heat exchanger 13. And
A water flow switch 14 for detecting the presence or absence of a water flow, a circulating pump 15 for circulating water in the bathtub 2 to the circulation path 11 in the pot, and a water inlet temperature from the bathtub 2 are provided upstream of the heat exchanger 13 in the pot internal circulation path 11. A thermistor 18 for detecting the temperature is provided, and a thermistor 19 for detecting the temperature of the hot water heated by the burner 12 is provided downstream of the heat exchanger 13 in the circulation path 11 in the shuttle. A main solenoid valve 21 and a main solenoid valve 22 are provided in a gas conduit 20 of the burner 12.

The internal circulation path 11 is connected to the outgoing pipe 6 and the return pipe 7 and communicates with the bathtub 2. The circulation heating unit 10
The water heater 30 is provided with a fan (not shown) for supplying combustion air, an ignition device, a combustion safety switch, and the like. The controller 50 is responsible for automatic bath water supply control, circulating heating control, general hot water supply control, etc., and comprises a CPU constituting a known logic operation circuit, a ROM for storing various programs, and a RAM for temporarily storing data. , An input interface for inputting signals from various sensors, an output interface for outputting drive signals to various actuators, and the like. In order to perform automatic hot water supply control described later, a ROM stores a heat release amount calculation program, a remaining hot water amount calculation program, a hot water supply instruction program, various numerical values, and the like. Similarly, the RAM is provided with a temperature memory area, a time memory area, and the like.

The basic operation of the bath kettle 1 having the above configuration will be described. First, when supplying hot water to the bathtub 2, the water supply valve 44 of the bath water supply passage 34 is opened to detect a water flow, and then the main electromagnetic valve 42 of the water heater 30 is opened to ignite the burner 40. Then, the water supply channel 31 is supplied from the water supply or the like by the supply water pressure.
Is heated by the heat of combustion of the gas in the burner 40 when passing through the heat exchanger 32, becomes hot water of a predetermined temperature, is sent out to the hot water supply passage 33, and flows from the point A through the bath hot water supply passage 34 to the hot water B. At this point, it flows into the circulation path 11 in the kettle, and is supplied to the bathtub 2 through the going pipe 6 and the returning pipe 7.

Here, the controller 50 performs feedback control based on the tap water temperature detected by the thermistor 39 and a preset temperature, and based on the incoming water temperature detected by the thermistor 37 and the incoming water flow rate detected by the flow rate sensor 36. The amount of combustion (proportional control valve 43) can be controlled in combination with the feedforward control. Here, if the external water tap 5 is opened instead of closing the water supply valve 44, the hot water heated by the heat exchanger 32 flows from the hot water supply path 33 to the external hot water supply pipe 4 via the general hot water supply path 35. Hot water can be used in toilets and showers.

When the water in the bathtub 2 is circulated and heated, that is, when the water is reheated, the water supply valve 44 is closed and the circulation pump 15 of the circulation path 11 in the pot is driven, and the water in the bathtub 2 is returned from the return pipe 7 to the circulation path 11 in the pot. And is circulated to the bathtub 2 via the outgoing pipe 6. Here, since the check valve 47 is provided in the bath hot water supply passage 34, the water in the bathtub 2 does not flow back to the hot water supply unit 30 to reach the hot water tap 5. Then, if the main solenoid valve 22 and the main solenoid valve 21 are opened and the burner 12 is ignited, the water flowing through the heat exchanger 13 of the in-kettle circulation path 11 is heated by the combustion heat. Each of the above operations is performed by the controller 50, and the user can issue various commands to the controller 50 using a known remote controller or the like.

Next, the automatic hot water supply control performed by the controller 50 as a feature of the present invention in the bath kettle 1 having the above-described configuration and basic operation will be described. In the automatic hot water supply control, when a predetermined amount of hot water is supplied from a state in which the bathtub 2 is empty, a predetermined reheating operation is performed to obtain a heat radiation amount W from the bathtub and piping, and when there is remaining hot water in the bathtub 2 The remaining amount of hot water is calculated by taking into account the amount of heat radiation W obtained, and the shortage of hot water is supplied from the hot water supply unit 30 and replenished, so that the hot water in the bathtub 2 is adjusted to an appropriate temperature and an appropriate amount.

The automatic hot water supply control routine will be described with reference to the flowchart of FIG. When entering this routine, first, the circulating pump 15 provided in the shuttle-inside circulating path 11 is driven (S1). This is to determine whether there is remaining hot water in the bathtub 2. Next, the controller 50 determines whether or not the water flow switch 14 is turned on (S
2). If the water flow switch 14 is not turned on in S2 (S2: No), it is determined that there is no remaining hot water in the bathtub 2, and in this case, the sequence from S3 to S9 without remaining hot water is executed. In the sequence without remaining hot water, a predetermined amount of hot water is supplied to the empty bathtub 2 and the bathtub 2 and the piping of the circulating heating unit 10 (the kettle circulation path 11, the outgoing piping 6, the return piping 7, and hereinafter simply referred to as "piping"). Find the heat dissipation of

First, hot water of the set hot water amount Qs stored in advance in the ROM of the controller 50 is supplied from the hot water supply unit 30 to the bathtub 2.
(S3). The supply hot water temperature at this time is a temperature Ts-α slightly lower than the set temperature Ts, and α is about 1 degree. Note that the set temperature Ts is a suitable bathing temperature, and is selected by the bather according to his / her preference from those stored in advance in the ROM of the controller 50 as a table. Then, the pump 15 is driven for a predetermined time to circulate hot water (S
4). This is to make the hot water temperature uniform. After the circulation, the temperature T1 of the hot water in the bathtub is detected by the thermistor 18 (S
5). The detected temperature T1 is stored in the temperature memory area of the RAM of the controller 50 for calculating the amount of heat radiation to be performed later in S9.

Then, the hot water is circulated and reheated by the circulating heating unit 10 until the hot water temperature reaches the set temperature Ts, and the time t1 (minute) required for the reheating is stored in the time memory area of the RAM (S6). This is because the time t1 depends on the amount of heat radiation affected by the outside air temperature and the like, and is therefore necessary for calculating the amount of heat radiation. After the completion of reheating to the set temperature Ts, the circulation by the circulation pump 15 is continued for a predetermined time t2 (minutes) (S7). The circulation time t2 is stored in the ROM of the controller 50 in advance. Then, at the end of the circulation, the temperature detected by the thermistor 18 is read (S8). Temperature T2 of remaining hot water
To know. The measured temperature T2 is stored in the temperature memory area of the RAM of the controller 50. Temperature T
2 is necessary for calculating the amount of heat radiation because it differs depending on the amount of heat radiation affected by the outside air temperature.

Then, the heat radiation amount is calculated (S9).
Since the bathtub 2 has the appropriate temperature and the appropriate amount, the process shifts to the heat retention mode of S18 and the remaining hot water empty sequence ends. The heat retention mode of S18 is a mode in which the bathtub temperature is read by the thermistor 18 at an appropriate frequency, and when the temperature is lower than the set temperature Ts, the temperature of the bathtub 2 is maintained at the set temperature Ts by reheating to the set temperature Ts. .

Here, the calculation of the heat radiation amount W in S9 will be described. What is calculated is the heat radiation from the bathtub 2 and the piping, but it is necessary to separately consider the heat radiation W1 during reheating and the heat radiation W2 during circulation (W = W
1 + W2). This is because during reheating, there is a large amount of heat radiation from the high-temperature hot water immediately after passing through the burner 12, whereas when only circulation is performed, the amount of heat radiation is small. First, the heat radiation W1 during reheating will be considered.

The heat radiation W1 is expressed by the following equation (1). W1 = K1 * R * t1 (1) Here, K1 (degree) is a parameter indicating the temperature drop of hot water at the time of reheating, and more specifically, the return pipe 7 after leaving the bathtub 2 and the circulation path in the kettle. 11. Bathtub 2 after going piping 6
Is the temperature drop up to In particular, most of the temperature drops from the high temperature state immediately after passing through the burner 12. K1 varies depending on the piping distance for each bath kettle, the type of bathtub 2, the presence or absence of a heat insulating material and a lid, and the like, and is strongly affected by the outside air temperature To. In the equation (1), R is a circulation flow rate (liter / minute). t1 is the time (minutes) required for the reheating in S6. Since the specific heat of water is 1 (kcal / (degrees / liter)), when multiplied by this, the unit on the left side of equation (1) becomes (kcal).

Next, the heat radiation W2 is expressed by the following equation (2). W2 = K2.times.R.times.t2 (2) where K2 (degrees) is a parameter indicating the temperature drop of the hot water during circulation. Specifically, after returning from the bathtub 2, the return pipe 7, the kettle circulation path 11 , The bathtub 2 again through the outgoing pipe 6
Is the main factor. K2, like K1, depends on various factors. t2 is the time (minutes) of the circulation performed in S7. Since the specific heat of water is 1 (kcal / (degrees / liter)), multiplying this results in (kcal) in the unit on the left side of equation (2).

Therefore, the total heat release amount W is expressed as follows: W = (K1 × R × t1) + (K2 × R × t2) (3) Here, K1 is naturally larger than K2 due to the large heat radiation from the hot water immediately after passing through the burner 12, but it can be considered that K1 = 2.0 × K2 (4) in an ordinary bath kettle. It is clear from our experiments that there is none. Therefore, by substituting equation (4) into equation (3), W = K2 * R * (2.0 * t1 + t2) (5) is obtained. Note that in equations (1) to (5), K1, K
Both 2 and R are unknown values per se.

On the other hand, considering the change in hot water temperature during the reheating and circulation performed in S6 and S7, the following holds: Qs = (Z1−W) / X (6) Here, Qs is the set hot water amount and Z1 is the burner 1
2 is the amount of heat (kcal) to the hot water, taking into account the thermal efficiency of the heat exchanger 13, W is the amount of heat radiation (kcal) from the pipes and bathtub 2, and X is the temperature of hot water (degrees) due to reheating. Is shown. Since the specific heat of water is 1 (kcal / (degrees / liter)), multiplying this gives the unit on the left side of equation (6) as (liter).

In this equation, Z1 is expressed as follows: Z1 = INP × η × t1 (7) Here, INP is the amount of heat supplied per hour (kc
al / min), which is determined by the gas flow rate of the main solenoid valve 22, and is stored as a table in the ROM of the controller 50. η is the thermal efficiency used for increasing the water temperature of the supplied heat amount, is a known value for each bath kettle, and is stored in the ROM of the controller 50.

In equation (6), W is nothing but the amount of heat dissipation W in equation (5). X is represented by X = T2−T1 (8). T1 and T2 are the hot water temperatures measured in S5 and S8, respectively. By substituting the right side of equation (5) for W in equation (6) and transforming the equation, the following equation is obtained: K2 * R = (Z1-Qs * X) / (2.0 * t1 + t2) (9) Since all the right-hand sides of the equation (9) are known values, it means that a parameter of (K 2 × R) ((degree · liter) / min) has been obtained. By substituting the equation (9) into the equation (5), W = Z1−Qs × X = INP × η × t1−Qs × (T2−T1) (10) was obtained, and the heat dissipation W was obtained. become.

The parameter K 2 × R has a dimension of the amount of heat radiation per time, is stored in the RAM of the controller 50, and is used for calculation of the remaining hot water amount Q described later. As described above, the sequence with no remaining hot water is performed in the empty bathtub 2.
Hot water and reheating, etc.
The amount of heat radiation affected by the outside air temperature is measured.

Next, the case where the water flow switch 14 is turned on in S2 (S2: Yes) will be described. In this case, the remaining hot water sequence from S10 to S17 is executed. In the remaining hot water sequence, predetermined additional heating and circulation are performed, the remaining hot water amount is calculated from the required time and the like at that time, and automatic hot water supply is performed as appropriate. Here, when calculating the remaining hot water amount, the calculation is performed with high accuracy by taking into account the heat release amount W obtained in the above-mentioned remaining hot water absence sequence.

First, the temperature detected by the thermistor 18 is read (S10). This is to know the initial temperature T3 of the remaining hot water. The measured initial temperature T3 is the value of RA
It is stored in the M temperature memory area. This is for calculating the remaining hot water amount to be described later. Next, reheating is performed to the set temperature Ts by the circulation heating unit 10 (S11). The time t3 (minutes) required for reheating is stored in the time memory area of the RAM. This is for calculating the remaining hot water amount to be described later. After the reheating to the set temperature Ts is completed, the circulation by the circulation pump 15 is continued for a predetermined time t2 (minutes) as in S7 (S7).
12). Then, at the end of the circulation, the detected temperature of the thermistor 18 is read in the same manner as in S8 (S13). This is to know the temperature T4 of the remaining hot water. The measured temperature T4 is stored in the temperature memory area of the RAM of the controller 50.

Here, the remaining hot water amount Q is calculated (S1).
4). The calculation of the remaining hot water quantity Q is based on the temperature T3, T4,
, T3, etc., based on the following equation. Q = (Z2−W3) / (T4−T3) (11) Here, Z2 represents the heating amount at the time of reheating in S11, and W3 represents the heat release amount at the time of reheating at S11 and the circulation at S12. T4 -T3 is, of course, the temperature difference before and after reheating and circulation. First, for Z2,
Similarly to the above Z1, it is expressed by the following equation: Z2 = INP × η × t3 (12), which is obtained from a known value.

Next, since the same considerations as for W can be applied to W3, W3 = K2 × R × (2.0 × t3 + t2) (13) as in the above equation (5). Since K2 × R in equation (13) is nothing but the one obtained in equation (9), W3 can be calculated, and all the right-hand sides of equation (11) are known values. Thus, the remaining hot water amount Q is calculated.

The calculated remaining hot water amount Q is equal to the set hot water amount Q.
It is determined whether there is more than s (S15). If there is more than the set hot water amount Qs (S15: Yes), S
The mode is shifted to the heat retention mode 18. When it is determined that the amount of hot water is not equal to or greater than the set hot water amount Qs (S15: No), hot water of an insufficient amount is added from the hot water supply unit 30 (S16). And
Since the temperature of the hot water drops slightly due to the added hot water, additional heating is performed until the temperature reaches the set temperature Ts (S17), and then the mode shifts to the heat retention mode of S18. Thus, the remaining hot water sequence ends.
As described above, in the remaining hot water sequence, the amount of hot water in the bathtub 2 is accurately calculated in consideration of the amount of heat radiation measured when the sequence without remaining hot water is executed, and if there is a shortage, the shortage is automatically supplied. .

As described in detail above, in the bath kettle with a water heater of the present embodiment, when a predetermined amount of hot water is supplied to the empty bathtub 2 and reheated to an appropriate temperature and an appropriate amount, piping and the like affected by the outside air temperature are used. The amount of heat released from the bathtub is calculated, and when adding hot water to the bathtub 2, the amount Q of remaining hot water is calculated in consideration of the amount of heat release, and the shortage is automatically supplied. In a bath kettle with a water heater that is actually installed at home, it is considered that the bathtub 2 is usually filled with an empty bath tub at least once every two to three days. Is executed, and the heat radiation amount W in the equation (10) is updated to a new value. Therefore, when the amount of hot water decreases during bathing, etc., the remaining hot water sequence is always executed based on the latest value of the heat release amount W. Therefore, the remaining hot water amount is accurately calculated regardless of seasonal changes and the like. Hot water supply and reheating are performed.

Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above-described embodiments, and it is easy to make various modifications without departing from the spirit of the present invention. It can be inferred.

[0040]

As is apparent from the above description, according to the bath kettle with a water heater of the present invention, the heat radiation amount affected by the outside air temperature is reheated by supplying a predetermined amount of hot water to an empty bathtub. When the hot water shortage occurs, the remaining hot water amount is calculated taking into account the amount of heat radiation, so the remaining hot water amount is calculated with high accuracy without being affected by the level of the outside air temperature, and Regardless of the year, it is possible to provide appropriate hot water supply and reheating with no excess or shortage.

[Brief description of the drawings]

FIG. 1 is a drawing showing the configuration of a bath kettle with a water heater.

FIG. 2 is a flowchart showing a remaining hot water control routine in a bath kettle with a water heater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bath kettle with water heater 2 Bathtub 10 Circulation heating part 14 Water flow switch 15 Circulation pump 18 Thermistor 30 Water heater part 50 Controller

Claims (3)

(57) [Claims] 1. Hot water supply means for supplying hot water to a bathtub, circulating heating means for circulating and heating hot water in the bathtub, hot water temperature detecting means for detecting hot water temperature in the bathtub, and hot water temperature detecting means. In a bathtub with a water heater having a heating control means for instructing the circulation heating means to perform circulating heating until the hot water temperature reaches a set temperature, a hot water presence / absence determination means for determining the presence / absence of hot water in a bathtub; A first hot water supply command means for instructing the hot water supply means to supply a predetermined amount of hot water having a temperature slightly lower than the set temperature to the bath tub when it is determined that there is no hot water in the bath tub; The hot water supplied in accordance with the instruction of the above is circulated to the set temperature by the circulating heating means, and at that time, a heat radiating amount calculating means for calculating a heat radiating amount under the influence of the outside air temperature or the like; If there is hot water When the hot water is supplied, the hot water is circulated to the set temperature by the circulating heating means, and the remaining hot water amount calculating means for calculating the remaining hot water amount in consideration of the heat release amount calculated by the heat release amount calculating means at that time; And a second hot water supply command means for automatically adding a shortage of hot water by the hot water supply means based on a calculation result of the calculation means. 2. The method according to claim 1, wherein the heat-dissipation-amount calculating means is configured to supply W = INP.times..eta..times.t1 -Qs.times. (T2 -T1) at the time of circulating heating to a set temperature after supplying a predetermined amount of hot water to an empty bath. The heat radiation amount W is calculated by an equation (INP is a gas input amount, η is a thermal efficiency, t1 is a heating time, Qs is a set hot water amount, and T2-T1 is a temperature rise of circulation heating). The bath kettle with a water heater described in 1. 3. The remaining hot water amount calculation means performs Q = (INP × η × t3−W3) / (T4−T3) (INP) during circulating heating to a set temperature when there is remaining hot water in the bathtub. Is a gas input amount, .eta. Is a thermal efficiency, t3 is a heating time, W3 is a heat release amount, and T4-T3 is a temperature rise of circulating heating). Bath kettle with water heater to be described.