JPH07103573A - Bath boiler with hot water supplying device - Google Patents

Abstract

PURPOSE:To optimize an additional supply of hot water by a method wherein, when the hot water is discriminated to be present in a bathtub, the hot water temp. is detected as the initial temp., a circulation heating is effected until a specific temp. is reached, the hot water is circulated, the hot water temp. is detected, the quantity of heat radiating to outside air is computed, from such data the amount of hot water in the bathtub is computed taking the amount of the radiating heat into consideration and hot water is supplied to make up for an insufficient amount. CONSTITUTION:Before hot water supply, a controller 50 drives a circulating pump 15 and, when a water flow switch 14 is on, the hot water is judged to remain in a bathtub 2. When the hot water remains, the hot water temp. is detected by a thermistor 18 and the detected temp. is stored in memory as the initial temp. T1. An additional heating is effected by a circulation heating part 10 until a prescribed temp. is reached and the additional heating time t1 is measured. The hot water is circulated by the circulating pump 15 only for a specific time t2 after reaching the specific temp. to measure the hot water temp. T2. The amount of the remaining hot water is computed from the quantity of heat of a burner 12 required for the additional heating, the amount of heat radiating by outside air temp., the degrees of raised temp., etc., according to a specified procedure. When the amount of the remaining hot water is short of the required amount in the bathtub 2, the hot water is supplied from a hot water supply part 30 to make up for the shortage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bathtub with a water heater, which is capable of supplying hot water heated by a water heater to a bathtub and circulatingly heating the hot water in the bathtub to reheat it. The present invention relates to a bath kettle with a water heater, which calculates the amount of hot water and automatically supplies the insufficient amount of hot water to bring the bath to a desired amount.

[0002]

2. Description of the Related Art Conventionally, a circulation heating circuit for forcibly circulating water in a bathtub by a pump and heating it by a heat exchanger installed in the middle of a circulation pipe, and another heat exchanger taken from water supply or the like. A bath kettle with a water heater having a hot water supply circuit for supplying heated hot water to a bathtub via a circulation circuit is used. This type of bath kettle with a water heater has a water temperature sensor, calculates the amount of hot water in the bath from the temperature rise when reheating, and automatically supplies the insufficient amount of hot water to reach the desired water level. There are also things. As an example of performing such control,
Examples thereof include those described in JP-A-61-15047. The control method disclosed in the same publication is to heat the hot water in the bathtub for a certain period of time, calculate the hot water amount in the bathtub from the temperature rise at that time, and determine the hot water supply amount of hot water based on the calculated value. This is the main point.

[0003]

However, the conventional water heater control disclosed in the above publication has the following problems. That is, in the water heater control of the above publication, basically, the amount of heat supplied when heated for a certain period of time is divided by the temperature rise at that time to calculate the amount of hot water, but when calculating the amount of heat added to the hot water Even if the heat efficiency of the exchanger is taken into consideration, the fact that heat is dissipated in each part such as the piping and bathtub is not considered. If this amount of heat radiation is always constant, the heat efficiency of the heat exchanger should be taken into consideration, but in reality, even the bath model of the same model will differ depending on the pipe length, etc., depending on the installation conditions, and the same bath Even in the kettle, it depends on the water temperature and the outside temperature. A particular problem is that there is a large difference in outside air temperature of more than 20 ° C. depending on the season, so the amount of heat radiation differs greatly between winter and summer, and the effect cannot be ignored.

In the summer, for example, the outside air temperature may be around 30 ° C. In that case, the difference between the hot water temperature and the outside air temperature is only about 10 ° C. Therefore, the amount of heat released is small, and most of the amount of heat supplied from the burner is used to raise the water temperature. Therefore, the water temperature increase range is large and the amount of hot water in the bathtub is calculated to be small,
A large amount of hot water will be supplied. On the other hand, at night in winter, the outside air temperature drops to about 0 ° C., in which case the difference between the hot water temperature and the outside air temperature reaches 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 amount of rise in water temperature is small compared to summer, and as a result, the amount of hot water in the bathtub is calculated to be considerably larger than it actually is, so the amount of hot water supplied is too small. That is, there is a tendency for the hot water to run short in the winter when a sufficient amount of hot water is required.

The present invention solves the above-mentioned problems of the prior art, and by taking into account the heat radiation from pipes, bathtubs, etc., the amount of hot water in the bathtub is calculated without being affected by the outside temperature, and it is related to the season. It is an object of the present invention to provide a bath kettle with a water heater that can appropriately determine the amount of hot water to be supplied and provide appropriate hot water.

[0006]

In order to achieve this object, a bath with a water heater according to the present invention comprises a hot water supply means for supplying hot water to a bathtub, a circulation heating means for circulatingly heating the hot water in the bathtub, and a bathtub inside. The presence or absence of hot water in the bathtub in the bathtub with a water heater having hot water temperature detecting means for detecting the hot water temperature of the hot water, and heating control means for controlling the circulating heating means based on the hot water temperature detected by the hot water temperature detecting means. Hot water presence / absence determining means, heat radiation amount calculating means for calculating the heat radiation amount due to the influence of the outside air temperature, and hot water amount calculating means for calculating the hot water amount in the bathtub in consideration of the heat radiation amount,
The gist of the present invention is to have hot water supply command means for automatically adding the amount of insufficient hot water by the hot water supply means based on the calculation result of the hot water quantity calculation means.

Here, the heat radiation amount calculation means calculates the heat radiation amount of the pipe from the circulation pipe of the circulation heating means and / or the heat radiation amount of the bathtub from the bathtub, and the heat radiation amount of the pipe is up to a certain temperature. When the hot water in the bathtub is circulated and / or heated and / or the hot water in the bathtub is circulated for a certain period of time, it is calculated by the circulation flow rate, the outside air temperature, the circulation heating time, and the circulation time. It is calculated from the temperature and the elapsed time. Then, the hot water amount calculating means is: Q = (IP × η × t1 −W) / (Y + T2 −T1) (IP is the gas input amount, η is the thermal efficiency, t1 is the circulation heating time, and W is the pipe discharge from the circulation pipe. The amount of heat, Y is the temperature drop due to heat radiation from the bathtub, and T2-T1 is the temperature rise of the circulation heating), and the amount Q of hot water in the bathtub is calculated.

[0008]

In the bathtub with a hot water supply device of the present invention having the above-described structure, the presence / absence of hot water in the bathtub first determines the presence / absence of hot water in the bathtub. When there is hot water in the bathtub, the hot water temperature detecting means detects the initial temperature of the hot water, and the circulation heating means circulates and heats the hot water in the bathtub to the set temperature under the control of the heating control means,
Further, the hot water in the bathtub is circulated for a predetermined time, and the hot water temperature detecting means detects the temperature of the hot water in the bathtub again. Then, the heat radiation amount calculation means calculates the heat radiation amount affected by the outside air temperature and the like, and the hot water amount calculation means calculates the hot water amount in the bath in consideration of the heat radiation amount,
When there is a shortage, the hot water supply means automatically supplies the shortage according to a command from the hot water supply instruction means.

In the bathtub with a water heater according to the second aspect of the present invention, the heat radiation amount calculating means circulates and heats the hot water in the bathtub to a certain temperature and / or circulates the hot water in the bathtub for a certain period of time. The heat radiation amount of the pipe is calculated from the circulation flow rate, the outside air temperature, the circulation heating time, and the circulation time, and / or
The bath heat dissipation is calculated from the outside air temperature and the elapsed time. In addition, in the bathtub with a water heater according to the invention of claim 3, the hot water amount calculating means includes the gas input amount IP, the thermal efficiency η, the circulation heating time t1, the heat radiation amount W of the pipe, the temperature drop Y due to the heat radiation of the bath, and the temperature increase of the circulation heating. From T2-T1, the amount Q of hot water in the bathtub is calculated by the following equation: Q = (IP * [eta] * t1-W) / (Y + T2-T1).

[0010]

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

The water heater 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 hot water outlet 33 connected to the downstream side of the heat exchanger 32
A bath hot water supply passage 34 and a general hot water supply passage 35, which are provided by branching the hot water discharge passage 33 at point A, constitute a flow passage. Water supply channel 31
A flow rate sensor 36 for detecting the flow rate, a thermistor 37 for detecting the incoming water temperature, and a thermistor 39 for detecting the hot water temperature are provided in the hot water outlet 33, respectively.

A burner 40 is provided below the heat exchanger 32, and a gas conduit 41 thereof is provided with an original solenoid valve 42 for opening and closing a gas flow path and a proportional control valve 43 for adjusting the gas flow rate. Bath hot water supply path 34 branched from the hot water supply path 33
Is a water supply valve 44 that opens and closes it, a flow rate sensor 45 that detects the flow rate of hot water supplied to the bathtub 2, an edge cutoff valve 46, and a check valve 4 that prevents backflow from the circulation heating unit 10 to the water heater 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 the general hot water supply passage 35 branched from the hot water discharge passage 33.

In the circulation heating section 10, an in-cylinder circulation path 11 for circulating the water in the bath 2 forms a flow path, and a burner 12 is provided in the middle thereof.
It has the heat exchanger 13 heated by. And
A water flow switch 14 for detecting the presence or absence of a water flow, a circulation pump 15 for circulating the water in the bathtub 2 to the bath circulation circuit 11, and an incoming water temperature from the bathtub 2 are provided on the upstream side of the heat exchanger 13 in the bath 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 on the downstream side of the heat exchanger 13 in the circulation path 11 in the kettle. The gas conduit 20 of the burner 12 is provided with a source solenoid valve 21 and a main solenoid valve 22. The in-kettle circulation path 11 is connected to the outflow pipe 6 and the return pipe 7 and communicates with the bathtub 2.
The circulation heating unit 10 and the water heater unit 30 are provided with a fan for supplying combustion air, an ignition device, a combustion safety switch, and the like, which are not shown. In addition to these, an outside air temperature sensor 9 for detecting the outside air temperature is provided.

The controller 50 has an automatic bath hot water supply control,
It controls circulation heating control, general hot water supply control, and the like, and includes a CPU that constitutes a known logical operation circuit, a ROM that stores various programs, and an RA that temporarily stores data.
M, 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, which will be described later, the ROM stores a hot water amount calculation program in the bathtub, a hot water supply command 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 bathtub 1 having the above construction will be described. First, when hot water is supplied to the bathtub 2, when the water supply valve 44 of the bath hot water supply passage 34 is opened and the water flow is detected, the original electromagnetic valve 42 of the water heater unit 30 is opened to ignite the burner 40. Then, when passing through the heat exchanger 32, the burner 40
Is heated by the heat of combustion of the gas in the tank to become hot water of a predetermined temperature, is sent to the hot water outlet path 33, flows from the point A into the bath internal circulation path 11 at the point B via the bath hot water supply path 34, and the outgoing pipe 6 and the return pipe It is supplied to the bathtub 2 through 7.

Here, the controller 50 performs feedback control based on the hot 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 combustion amount (proportional control valve 43) can be controlled in combination with the feedforward control. Here, if the water supply valve 44 is closed and the external hot water tap 5 is opened instead, the hot water heated in the heat exchanger 32 flows from the hot water outlet 33 to the external hot water supply pipe 4 via the general hot water supply passage 35. You can use hot water in the bathroom or shower.

When the water in the bathtub 2 is circulated and heated, that is, reheated, when the water supply valve 44 is closed and the circulation pump 15 of the in-cylinder circulation line 11 is driven, the water in the bathtub 2 is returned from the return pipe 7 to the in-cylinder circulation line 11. 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 and reach the hot water tap 5. And the former solenoid valve 21,
When the main solenoid valve 22 is opened and the burner 12 is ignited, the water flowing through the heat exchanger 13 in the in-cylinder circulation path 11 is heated by the combustion heat. Each operation described above is performed manually or by the controller 50, and the user can issue various commands to the controller 50 by using a known remote control device or the like.

Next, the automatic hot water supply control executed by the controller 50, which is a feature of the present invention, in the bathtub 1 having the above-described structure and basic operation will be described. When there is hot water in the bathtub in the bathtub 2, the automatic hot water supply control calculates the amount of hot water in the bathtub from the amount of heat supplied and the rising temperature in consideration of the heat radiation at that time, and the amount of hot water is insufficient. The hot water is supplied from the hot water supply unit 30 to replenish the water, and the hot water in the bathtub 2 is adjusted to an appropriate temperature and amount.

The automatic hot water supply control routine will be described with reference to the flowchart of FIG. When this routine is entered, first, the circulation pump 15 provided in the shuttle circulation circuit 11 is driven (S1). This is for determining whether or not there is hot water in the bathtub 2. Next, the water flow switch 14
The controller 50 determines whether or not is turned on (S
2). When the water flow switch 14 is not turned on in S2 (S2: No), it is determined that there is no hot water in the bathtub in the bathtub 2, and in this case, the set amount of hot water stored in advance in the ROM of the controller 50 is used. The water is supplied from the water heater 30 to the bathtub 2 (S3).

Then, the temperature detected by the thermistor 18 is read (S4), and the controller 50 judges whether the temperature is equal to or higher than the set temperature Ts (S5). The set temperature Ts is suitable for bathing and is selected by the bather according to his / her preference from a table stored in the ROM of the controller 50 in advance. When the temperature is equal to or higher than the set temperature Ts (S5: Y
In es), the process directly shifts to the heat retention mode of S16 described later. When the temperature is equal to or lower than the set temperature Ts (S5: No), the circulation heating unit 10 reheats the circulation to the set temperature Ts (S6). After the hot water reaches the set temperature Ts, the circulation is continued for a predetermined time for stirring (S7), and then S described later is performed.
It shifts to 16 heat retention mode.

When the water flow switch 14 is turned on in S2 (S2: Yes), it is determined that there is hot water in the bathtub 2 and the calculation of the hot water amount Q in the bathtub, which is a feature of this routine, is performed. 2 and circulation piping (cylinder circulation path 11, forward piping 6,
The heat is radiated from the return pipe 7, hereinafter simply referred to as "pipe"). The amount Q of hot water in the bathtub is calculated based on the time required for circulation and heating of the hot water, the temperature change during that time, and the like. Therefore, first, the temperature detected by the thermistor 18 is read while continuing the circulation without stopping the circulation pump 15 (S8).
This is to know the initial temperature T1 of the hot water in the bathtub. The measured initial temperature T1 is stored in the temperature memory area of the RAM of the controller 50. This is for calculating the amount of hot water in the bath, which will be described later.

Next, the circulating heating unit 10 sets the set temperature Ts.
Boil up to (S9). During the reheating, the hot water temperature θ1 returned to the burner 12 is detected by the thermistor 18, the hot water temperature θ2 coming from the burner 12 is detected by the thermistor 19, and these are stored in the temperature memory area of the RAM of the controller 50. . Also, the time t1 (minutes) required for reheating is stored in the time memory area of the RAM. This is for calculating the amount of hot water in the bath, which will 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) (S10). The circulation time t2 is stored in advance in the ROM of the controller 50. Then, at the end of circulation, the temperature detected by the thermistor 18 is read (S11). This is to know the temperature T2 of the hot water in the bathtub.
The measured temperature T2 is stored in the temperature memory area of the RAM of the controller 50. This is for calculating the amount of hot water in the bath, which will be described later.

Here, the amount Q of hot water in the bathtub is calculated (S
12). The amount of hot water Q in the bathtub is calculated by using the temperatures T1, T2, θ.
It is performed based on 1, θ2, time t1, t2, etc., which will be described later in detail. Then, it is determined whether or not the calculated amount of hot water is equal to or more than the set amount of hot water stored in advance in the ROM of the controller 50 (S13). When there is more than the set amount of hot water (S
13: Yes), the process directly shifts to the heat retention mode of S16 described later. When it is determined that the amount of hot water is not more than the set amount (S13: No), the insufficient amount of hot water is supplied to the water heater unit 3
Add hot water from 0 (S14). Then, since the hot water temperature is slightly lowered by the supplementary hot water, additional heating is performed until the temperature reaches the set temperature Ts (S15), and then the heat retention mode of S16 is entered. S
In the heat retention mode of 16, the bath temperature is read by the thermistor 18 at an appropriate frequency, and when the temperature is lower than the set temperature Ts, it is heated to the set temperature Ts to maintain the hot water temperature of the bath 2 at the set temperature Ts.

Next, the amount Q of hot water in the bathtub to be carried out in S12.
Details of calculation of (liter) will be described. The amount of hot water Q in the bathtub is basically calculated based on the following equation (1). Q = (Z−W) / (X + Y) (1) Here, Z is the heating amount (kcal) to the hot water by the burner 12, which takes into account the thermal efficiency of the heat exchanger 13, and W is the discharge from the pipe. The amount of heat (kcal), X represents the rising temperature (degrees) of the hot water due to reheating, and Y represents the temperature drop (degree) of the hot water due to heat radiation from the bathtub 2.

That is, if the heating amount Z is divided by the rising temperature X, an approximate amount of hot water Q is obtained because the specific heat of water is 1 (kcal / (degree.liter)). Considering that the heat is not radiated from the pipe and does not contribute to the temperature rise X, and that the actually measured temperature rise X is small by the temperature drop Y due to heat radiation from the bathtub 2, the more accurate amount Q of hot water in the bathtub.
Is calculated. This heat radiation is largely influenced by the difference in the outside air temperature To depending on the season and causes an error in the hot water supply control. This is to alleviate this and perform high-precision hot water supply control. The following will be described in order.

Z is calculated by the equation (2). Z = IP × η × t1 (2) Here, IP is the heat supply amount per hour (kcal / min) and is determined by the gas flow rate, and the controller 50
Is stored as a table in the ROM. η is a thermal efficiency used to raise the water temperature in the supplied heat amount, which is a known value for each bath and is stored in the ROM of the controller 50. t1 is the reheating time (minutes) in S9.

Next, W is the sum (W = W1 + W2) of the heat dissipation W1 of the pipe during reheating (S9) and the heat dissipation W2 of the pipe during subsequent circulation (S10). Burner 1 when reheating
Although there is a great deal of heat radiation from the hot water immediately after passing through No. 2, it is necessary to distinguish between W1 and W2 because the heat radiation is small when only circulating. The pipe heat radiation W1 at the time of reheating is calculated by the equation (3). W1 = K2 x R x t1 (3)

Here, K2 is the heat radiation temperature drop (degree) of the pipe during reheating, and R is the circulating flow rate of the pipe (liter / min).
Represents K2 is a function of the outside air temperature To and the pipe distance L. This is because the lower the outside air temperature To and the longer the piping distance L, the greater the heat radiation from the piping. Values of K2 for various values of the outside air temperature To and the piping distance L are stored in the ROM of the controller 50 as a table. Figure 3 shows the value of K2 when the outside air temperature To is 5 ℃ or 30 ℃.
Is shown in the graph. The outside air temperature To is measured by the outside air temperature sensor 9, and the pipe distance L and the circulation flow rate R are calculated by the procedure described later. The specific heat of water is 1 (kcal / (degrees / liter))
Therefore, if this is multiplied, the unit on the left side of equation (3) becomes (kcal).

The heat radiation W2 from the pipe during circulation is calculated by the equation (4). W2 = K3 * R * t2 (4) Here, K3 is the heat radiation temperature drop (degrees) of the pipe during circulation, and t2 is the circulation time (minutes) of S10. K
Similarly to K2, 3 is a function of the outside air temperature To and the pipe distance L. Values of K3 for various values of the outside air temperature To and the piping distance L are stored in the ROM of the controller 50 as a table. Outside temperature To is 5 ℃ or 30 ℃
The value of K3 is shown in the graph of FIG. When the outside air temperature To is equal to the piping distance L, the value of K3 is smaller than the value of K2. This is because there is no great heat radiation immediately after passing through the burner 12. Since the specific heat of water is 1 (kcal / (degrees / liter)), multiplying this gives the unit on the left side of equation (4) is (kcal).

Next, the derivation of the circulation flow rate R and the piping distance L necessary for calculating the piping heat radiation W1 and W2 will be described.
The circulation flow rate R is determined by the output of the circulation pump 15 and the flow path resistance of the pipe. The output of the circulation pump 15 is a known value for each pump model, but the flow path resistance of the pipe is mainly determined by the pipe distance L, and the pipe distance L individually differs depending on the structure of the bathroom, the arrangement of the bathtub, and the like. . Therefore, in this routine, the circulation flow rate R is calculated from the hot water temperature rise value due to the additional heating, and the pipe distance L is obtained from the calculated value.

The circulation flow rate R is calculated by the equation (5). R = OUT / ([theta] 2- [theta] 1) (5) Here, OUT is a coefficient representing the output of the burner 12, and its unit is ((degrees / liter) / min) and is stored in the ROM of the controller 50 in advance. ing. θ1 and θ2 are the return hot water temperature to the burner 12 (thermistor 18) and the hot hot water temperature from the burner 12 (thermistor 1) measured in S9.
9). That is, the equation (5) is to calculate the flow rate by back calculation from the fact that the rise in the hot water temperature is small if the flow rate is large even if the output of the burner 12 is constant.

The piping distance L and the circulation flow rate R are in a substantially inversely proportional relationship as shown in the graph of FIG. 5, and the piping distance L for each value of the circulation flow rate R is the ROM of the controller 50.
Is stored in advance as a table. Therefore, (5)
If the circulation flow rate R is calculated based on the equation, the piping distance L can also be obtained from the graph of FIG. Thus the circulation flow rate R
And the pipe distance L are obtained, and thus the pipe heat radiations W1 and W2 are obtained.

X (the rising temperature of the hot water) in the equation (1) is (6)
Calculated by the formula. X = T2-T1 (6) where T1 is the initial temperature measured in S8 and T
2 is the temperature after reheating and circulation measured in S11.

Y in the equation (1) (temperature drop of hot water due to heat radiation from the bathtub) is calculated by the equation (7). Y = K1 × (t1 + t2) (7) Here, K1 is the temperature drop rate (degrees / minute) of hot water due to heat radiation from the bathtub 2, and is a function of the outside air temperature To. The value of K1 for various outside air temperatures To is R of the controller 50.
It is stored as a table in the OM. The value of K1 increases as the outside air temperature To decreases. The manner in which the temperature of the hot water drops due to heat dissipation from the bathtub is shown in the graph of FIG. Since the heat radiation of the bath is hardly affected by whether or not the burner 12 is heating, Y can be obtained by multiplying the sum of the reheating time t1 and the circulation time t2 by K1. From the above, all of Z, W, X and Y in the equation (1) are obtained, and the hot water amount Q in the bathtub is calculated. Thereafter, hot water supply and the like after S13 described above are performed.

As described above in detail, in the bathtub with a water heater of this embodiment, when calculating the amount Q of hot water in the bathtub, the heat radiation from the pipe or the bathtub greatly affected by the outside air temperature To is taken into consideration in the bathtub. The hot water amount Q is calculated, and if there is a shortage, the shortage is automatically supplied. Therefore, regardless of the season, the amount of hot water Q in the bathtub can be calculated with high accuracy, and proper hot water supply / reheating can be performed without excess or deficiency. The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above embodiments, and it can be easily inferred that various modifications and improvements can be made without departing from the spirit of the present invention. It is a thing. For example, although the sensor 9 for detecting the outside air temperature is used in the present embodiment, the temperature sensor for detecting the incoming water temperature may be used in common for simplification.

[0036]

As is apparent from the above description, according to the bath tub with the water heater of the present invention, the amount of hot water in the bathtub is calculated in consideration of the heat radiation from the bathtub / pipe. Therefore, the amount of hot water in the bathtub can be calculated with high accuracy without being affected by the change in the outside air temperature, and appropriate hot water supply and reheating can be performed regardless of the season regardless of the season.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing a hot water control routine in the bathtub of the bath with a water heater.

FIG. 3 is a graph showing a pipe temperature drop (K2) during reheating.

FIG. 4 is a graph showing a pipe temperature drop (K3) during circulation.

FIG. 5 is a graph showing the relationship between piping distance and circulation flow rate.

FIG. 6 is a graph showing a bath temperature drop (K1).

[Explanation of symbols]

 1 Bathtub with water heater 2 Bathtub 9 Outside air temperature sensor 10 Circulation heating part 14 Water flow switch 15 Circulation pump 18 Thermistor 19 Thermistor 30 Water heater part 50 Controller

Claims (3)

[Claims] 1. A hot water supply means for supplying hot water to a bathtub, a circulation heating means for circulatingly heating hot water in the bathtub, a hot water temperature detecting means for detecting hot water temperature in the bathtub, and hot water detected by the hot water temperature detecting means. In a bathtub with a water heater having heating control means for controlling the circulation heating means based on temperature, there is a hot water presence / absence determining means for determining the presence / absence of hot water in the bathtub and a heat radiation amount due to the influence of the outside air temperature and the like. A heat radiation amount calculation means, a hot water amount calculation means for calculating the hot water amount in the bathtub in consideration of the heat radiation amount, and a hot water supply command means for automatically adding the shortage hot water amount by the hot water supply means based on the calculation result of the hot water amount calculation means. A bath kettle with a water heater. 2. The heat radiation amount calculation means calculates a pipe heat radiation amount from a circulation pipe of the circulation heating means and / or a bath heat radiation amount from a bathtub, and the pipe heat radiation amount is a bath temperature up to a certain temperature. When the hot water inside is circulated and heated and / or when the hot water inside the bath is circulated for a certain period of time, it is calculated by the circulation flow rate, the outside air temperature, the circulation heating time and the circulation time, and the bath heat radiation amount is the outside air temperature. The bath cooker with a water heater according to claim 1, wherein the bath cooker is calculated by the following formula: 3. The amount of hot water calculating means is Q = (IP × η × t1 −W) / (Y + T2 −T1) (IP is a gas input amount, η is thermal efficiency, t1 is a circulation heating time, and W is a circulation pipe. The amount of hot water in the bathtub is calculated by the equation: Y is the heat radiation amount from the pipe, Y is the temperature drop due to heat radiation from the bathtub, and T2-T1 is the temperature rise due to circulation heating. Bath pot with water heater.