JPH10325599A - Hot water supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a cold water sandwiching phenomenon from occurring by using a reheating command as a trigger for starting heating operation of a hot water supply heat exchanger in a hot water supply apparatus wherein the hot water supply heat exchanger and a bathtub water reheating heat exchanger are built in. SOLUTION: When a power source is turned on, a controller 50 waits a hot water supply demand, and if water flow to a hot water supply heat exchanger 5 is detected on the basis of water inflow amount detected by a water inflow sensor 31, the decision that a hot water supply demand is issued is made. A hot water supply burner 13 is ignited to perform hot water supply combustion. After that, a hot water supply cock 23 is closed to stop water flow to the hot water supply heat exchanger 5, the hot water supply combustion is interrupted and hot water supply demand waiting status, in which hot water supply combustion can immediately be started if the hot water supply cock 23 is opened, is established. If a bathtub water reheating command is issued, the hot water supply burner 13 is burned at a low heating power or is burned intermittently to heat the hot water supply heat exchanger 5 and hot water supply demand is waited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water heater having a built-in heat exchanger for hot water supply and a heat exchanger for post-bath heating, and more particularly to keeping the heat exchanger for hot water supply in a hot water supply standby state. The present invention relates to a water heater having a heating function.

[0002]

2. Description of the Related Art In a conventional water heater, when a hot water tap is closed after hot water is supplied, combustion of the burner is stopped, and the burner is not ignited until the next hot water supply request. Therefore, when the hot water supply is stopped, the heating is stopped and the heat exchanger cools down, and the temperature of the hot water inside gradually decreases. As a result, when the standby time from the stop of hot water supply to the next hot water supply is long, the temperature of hot water to be discharged from the heat exchanger is much lower than the target temperature, and unexpected cold water is discharged from curan or the like. Hot water at a desired temperature is obtained only after the hot water remaining in the heat exchanger is discharged. Such a temporary decrease in the tapping temperature at the initial stage of re-hot water supply is called a so-called cold water sandwich phenomenon, and gives the user discomfort.

[0003] As a method of solving the cold water sandwich phenomenon described above, Japanese Patent Application Laid-Open No. 6-159671 and
A measure disclosed in JP-A-6-117689 is known. Here, the measures disclosed in JP-A-6-159671 and JP-A-6-117689 disclose intermittently burning a burner during hot water supply standby to perform heat retention heating.
By this heat retaining operation, the water in the heat exchanger is kept warm. In the prior art, the timing for performing the heat retaining operation is controlled solely by time. That is, in the prior art, after a certain period of time in anticipation of a drop in the temperature of hot water in the heat exchanger has elapsed since the hot water supply was stopped,
A warming operation is performed.

[0004]

The prior art water heaters are:
The cold water sandwich phenomenon is less likely to occur than in the conventional water heater. However, when the conventional technology is applied to a forced-supply / exhaust water heater having a heat exchanger for additional bath heating, the original effect of the invention cannot be obtained, and the cold water sandwich phenomenon frequently occurs. . Hereinafter, the reason will be described.

FIG. 1 is a piping diagram of a forced water supply / exhaust water heater having both a heat exchanger for additional bathing and a heat exchanger for hot water supply. FIG. 2 is a configuration diagram of an air supply case having a structure different from the structure adopted in FIG. The piping system of the water heater of FIG. 1 will be briefly described as follows. In addition, the piping system of the water heater 100 shown in FIG. 1 is the same as the water heater 1 of an embodiment of the present invention described later. Water heater 100 shown in FIG.
Has a built-in hot water supply circuit and a hot water supply circuit around the hot water supply case 2. The inside of the hot water supply case 2 of the water heater 100 is partitioned into two parts, and a heat exchanger 3 for additional bathing is provided in one partition, and a heat exchanger 5 for hot water supply is provided in the other partition. Have been.

A burner 6 is provided inside the hot water supply case 2. The burner 6 is internally partitioned into a plurality of sections, and solenoid valves 7, 8, 9, and 10 are provided corresponding to each partition. The portion directly below the additional heat exchanger 3 to which the solenoid valve 7 is connected functions as a second-burner burner 12 and is directly below the hot water supply heat exchanger 5 to which the solenoid valves 8, 9, and 10 are connected. The part functions as a hot water supply burner 13. Each of the solenoid valves 7, 8, 9, and 10 is a gas proportional valve 15
Is connected to the gas supply source 16. One air supply fan 11 is provided below the hot water supply case 2, and the air supply fan 11 sends air to the burner 6. The upper part of the hot water supply case 2 is united and connected to the exhaust pipe 14.

[0007] Inside the water heater 100, there is formed a reheating circuit through which hot water passes through a heat exchanger 3 for reheating bath, and a hot water circuit through which hot water passes through a heat exchanger 5 for hot water supply. . The reheating circuit is a circuit for circulating the hot water in the bathtub 17 through the heat exchanger 3 for reheating the bath, and a pump 20 and a flow rate switch 21 are connected on the way.

On the other hand, the hot water supply circuit is a circuit for supplying hot water from a hot water tap 23 such as a currant or a shower. More specifically, the hot water supply circuit includes a high-temperature hot water circuit 27 through which hot water flows from the water supply source 25 via the hot water supply heat exchanger 5, and a bypass passage 28 through which only water flows. In the high temperature hot water circuit 27, a water input temperature sensor 30 and a water input amount sensor 31 are connected between the water supply source 25 and the hot water supply heat exchanger 5. Here, the incoming water temperature sensor 30 detects the temperature Tc of the incoming water into the hot water supply heat exchanger 5, and the incoming water amount sensor 31 detects the amount of incoming water Qc to the hot water supply heat exchanger 5. is there. A hot water temperature sensor 32 is provided at a hot water outlet of the hot water supply heat exchanger 5. The high-temperature hot water temperature sensor 32 detects the temperature Th of the hot water heated by the hot water supply heat exchanger 5.
Is to be detected.

The bypass passage 28 is a circuit for connecting the water supply source 25 and the tapping side of the hot water supply heat exchanger 5, and is provided with a flow control valve 33 for adjusting the bypass flow in the middle.
The opening of the flow control valve 33 is adjusted by a stepping motor.

A temperature sensor 34 and an overflow servo valve 35 are provided on the downstream side of the connecting portion between the bypass 28 and the hot water supply heat exchanger 5 on the tapping side. Temperature sensor 34
Detects the hot water supply temperature Tm after mixing. The overflow servo valve 35 limits the amount of hot water discharged when the flow rate to the hot water supply heat exchanger 5 exceeds the maximum heating capacity. The hot water tap 23 is provided downstream of the overflow servo valve 35. A branch pipe 37 is provided at an intermediate portion between the overflow servo valve 35 and the hot water tap 23, and is connected to an additional cooking circuit via a solenoid valve 44, check valves 45 and 46, and a flow sensor 47. This branch pipe 37
Is for dropping hot water into the bathtub 17.

The water heater 100 is controlled by a controller 50
And an operation unit (remote controller) 51. The controller 50 mainly performs a tapping operation and a warming operation. The operation unit 51 includes an operation switch 52 for turning on power to the controller 50, a setting switch 53 for setting a desired target temperature Ts, a heat insulation switch 54 for enabling a heat insulation operation, and a liquid crystal display unit 55. I have. 60 is an operation unit in the bathtub provided in the bathroom,
By operating the operation unit 60 in the bathtub, an additional cooking instruction is issued to the controller, and additional cooking is performed.

According to the control of the water heater of the prior art, after a certain period of time has passed since the tapping from the hot water tap 1 was stopped,
For example, after 5 minutes, the warming operation is started. That is, when the temperature of the hot water in the hot water supply heat exchanger 5 drops, the solenoid valves 8, 9.10 are opened, the hot water burner 13 is intermittently burned, and the hot water in the hot water supply heat exchanger 5 is heated. , The temperature of hot water is raised. However, if the additional heating of the bath is performed before the above-mentioned fixed time elapses, the temperature of the hot water in the hot water supply heat exchanger 5 decreases at a speed higher than originally planned, and the additional cooking is performed. If hot water is supplied between the start and the start of the heat retention operation, hot water with a low temperature will be discharged.

That is, the water heater having the configuration shown in FIG. 1 has only one air supply fan 11, so that the air supply fan 11 needs to be started in order to burn the burner 12 for additional cooking. . However, when the air supply fan 11 is started, air is inevitably supplied also to the hot water supply burner 13 side.
The hot water supply heat exchanger 5 is exposed to the ventilation. Therefore, if additional cooking is performed during the hot water supply standby, the temperature of the hot water in the hot water supply heat exchanger 5 drops within an extremely short period of time, and unexpected cold water is discharged from the hot water or the like. That is, a cold water sandwich phenomenon occurs, giving the user discomfort.

In the above description, the case where only one air supply fan 11 is provided in the hot water supply case 2 has been described as an example.
A similar problem occurs when employing a configuration having two air supply fans 40 and 41 as described above. That is, as shown in FIG.
Even when the hot water supply case 42 is provided with two air supply fans 40 and 41 and only the post-cooking burner 12 is burned, both air supply fans in the hot water supply case 2 are balanced to supply air. The air fans 40 and 41 must be started. Therefore, even in the configuration having two air supply fans 40 and 41, if additional cooking is performed during standby for hot water supply, the inside of the heat exchanger 5 for hot water supply is exposed to ventilation, and the Then, the temperature of the hot water in the hot water supply heat exchanger 5 decreases, and unexpected cold hot water is discharged from the hot water tap 23.
Therefore, the present invention focuses on the above-mentioned problems of the prior art,
An object of the present invention is to provide a water heater having both a heat exchanger for hot water supply and a heat exchanger for post-bath cooking, and having a configuration in which a cold water sandwich phenomenon does not occur.

[0015]

Means for Solving the Problems According to the first aspect of the present invention for achieving the above-mentioned object, the present invention has both a heat exchanger for hot-bath heating and a heat exchanger for hot-water supply, and responds to the hot-chamber instruction. The heat exchanger for bath heating is heated accordingly, the heat exchanger for hot water supply is heated according to the hot water supply command, and is discharged from the heat exchanger for hot water supply. When there is no hot water from the heat exchanger for hot water supply, the heat for hot water supply is supplied. In a water heater in which a heat-retaining operation is performed to keep the heat of a heat exchanger in a hot-water supply heat exchanger by keeping it warm, a hot-water supply characterized by performing a heat-retention operation of the hot-water supply heat exchanger starting with an additional cooking instruction. It is a vessel.

[0016] In the water heater of the present invention, the warming operation of the heat exchanger for hot water supply is performed in response to the additional cooking instruction. Therefore, cooling of hot water in the hot water supply heat exchanger due to ventilation during additional cooking is prevented, and the temperature of hot water in the hot water supply heat exchanger is kept within a target value.

A second aspect of the present invention for achieving the same object.
The invention described in (1) has both a heat exchanger for bath heating and a heat exchanger for hot water supply, wherein the heat exchanger for bath heating is heated in response to the heat-up command, and the heat exchanger for hot water supply in response to the hot-water supply command. The heat exchanger is heated and discharged from the hot water supply heat exchanger. When there is no hot water from the hot water supply heat exchanger, the heat retaining operation is performed to keep the hot water supply heat exchanger warm and keep the hot water in the hot water supply heat exchanger. In the water heater to be performed, the warming operation is performed starting from the earlier of the time when the additional heating instruction is given or the predetermined time has elapsed after the hot water supply from the hot water supply heat exchanger is stopped. It is a water heater characterized by the above.

In the hot water heater of the present invention, during the hot water supply standby state, the warming operation is performed when an additional cooking instruction is given or when a predetermined time has elapsed, whichever comes first. Therefore, not only the temperature drop of the hot water in the hot water supply heat exchanger due to natural cooling but also the temperature drop of the hot water due to the ventilation at the time of additional cooking is prevented. Therefore, the temperature of the hot water in the hot water supply heat exchanger is always kept within the target value.

According to a third aspect of the present invention, the state of the hot water in the heat exchanger is checked prior to the warming operation, and the warming operation is performed when the required amount of hot water is present. The water heater according to claim 1 or 2, wherein when the amount of hot water is less than a required amount, execution of the heat retaining operation is prohibited.

In the present invention, in addition to the functions and effects of the above-described invention, consideration is given to improvement in safety and durability of the heat exchanger. That is, the warming operation is performed during hot water supply standby, and heating is performed in a state where there is no movement of hot water in the hot water supply circuit. There is no problem if hot water is present in the heat exchanger for hot water supply when the heat retention operation is performed, but if the hot water has run out for some reason during hot water supply standby, the heat exchanger is emptied. It will be fired. This may cause fire or damage to the heat exchanger. On the other hand, in the present invention, prior to the warming operation, the existence state of the hot water in the heat exchanger is checked, and when the hot water is present at a predetermined amount or more, the warming operation can be performed. Prohibits the execution of the warming operation. This prevents the heat exchanger from being idled.

According to a fourth aspect of the present invention, which is a further improvement of the above invention, the means for checking the presence or absence of hot water in the heat exchanger performs the tapping operation before executing the heat retaining operation, prior to the heat retaining operation. 4. The water heater according to claim 3, wherein the water heater is operated by confirming whether or not the water heater has been turned on.

The water heater of the present invention indirectly recognizes whether or not there is hot water in the heat exchanger by checking whether or not the tapping operation has been performed before performing the heat retaining operation. Things.

[0023]

Embodiments of the present invention will be described below. FIG. 3 is a flowchart illustrating control of the water heater according to the embodiment of the present invention. FIG. 4 is a timing chart illustrating control of the water heater according to the embodiment of the present invention. The mechanical configuration and piping system of the water heater 1 of the present embodiment are the same as those of the water heater 100 of FIG. 1 described above. In addition, the control of the heat retention operation is performed by the controller 50 and the operation unit 51, which is the same as in the related art. However, the water heater 1 of the present embodiment is characterized in that the warming operation is performed with the signal of the additional cooking instruction as a start.
Hereinafter, the operation of the water heater 1 of the present embodiment will be described. First, the operation switch 52 of the operation unit 51 is operated to operate the controller 50.
Is turned on, and control is started. That is, the tapping operation is enabled. In the flowchart of FIG.
A start state, in the timing chart of FIG. 4, in the state of t _1.

Thereafter, controller 50 waits for a hot water supply request. The presence or absence of a hot water supply request is determined based on the incoming water amount Qc detected by the incoming water amount sensor 31. That is, if the curan or the like is opened to a certain degree or more and water is passed through the hot water supply heat exchanger 5, it is determined that a hot water supply request has been made (step 1). Then the process proceeds to Step 2, and igniting the hot water supply burner 13 to the hot water supply combustion (Fig. 4 t _2). Specifically, the hot water at the target hot water supply temperature Ts is supplied to the hot water tap 23 based on the known combustion control, that is, based on the detection outputs from the sensors 30, 31, 32, and 34.
The feedforward and feedback combustion control is performed so that hot water is discharged from the hot water. At this time, the hot water supply history flag is set to "1", and it is recorded that hot water has been supplied. That is, it is indirectly confirmed that hot water exists in the hot water supply heat exchanger 5.

During the hot water supply combustion, the hot water having a predetermined temperature Th in the hot water supply heat exchanger 5 and the water flowing through the bypass 28 are mixed, and immediately after the start of hot water supply, the target hot water supply temperature Ts is reduced. Hot water is supplied.

Thereafter, when the hot-water tap 23 is closed and the water supply to the hot-water supply heat exchanger 5 is stopped, the hot-water supply combustion is stopped in step 4 and the hot-water supply standby state is established. At the same time, the timer is started. In the timing chart of FIG.
For example hot water burned in t ₃ is assumed to have been stopped.

In the water heater 1 of this embodiment, this state is as follows.
It is in a state of waiting for a hot water supply request and an additional cooking request for 5 minutes. That is, as shown in the flowchart of FIG. 3, it is checked whether or not the hot water tap 23 is opened in step 5, and if the hot water tap 23 is opened, the process immediately returns to step 2 to start the above-described hot water combustion. Conversely, if NO is determined in step 5, the process proceeds to step 6 to check whether or not there is a request for additional cooking. Here, if there is no instruction for a request for additional cooking, the process proceeds to step 7, and it is checked whether or not 5 minutes have elapsed since the stoppage of the hot water supply combustion. If 5 minutes have not passed, return to step 5,
Thereafter, steps 5, 6, and 7 are repeated until it is determined in step 7 that 5 minutes have elapsed.

If there is a command for a request for additional cooking during the repetition of steps 5, 6, and 7, the process proceeds from step 6 to step 8 to perform a heat retaining operation. As described above, when additional cooking is performed in a hot water supply standby state, in other words, a state in which the hot water supply heat exchanger 5 is not heated, the hot water supply heat exchanger 5 is forcibly cooled by the air supply fan 11, and The temperature of the hot and cold water in the heat exchanger 5 decreases. Therefore, in the water heater 1 of the present embodiment, one of the solenoid valves 7, 8, 9, and 10 is opened or these are opened intermittently, and the hot water burner 13 is opened.
Is burned with a small thermal power or intermittently to heat and heat the hot water supply heat exchanger 5. Explaining with reference to the timing chart of FIG. 4, there is a request for additional cooking at t ₄ , and from t ₃ to t ₄
If the time is less than 5 minutes, the solenoid valves 7, 8,
9 and 10 are opened in a pulse manner for a time T ₁ , and this is repeated twice with a predetermined interval time T ₂ interposed therebetween, so that the hot-water supply heat exchanger 5 is kept warm.

Then, the process proceeds to step 9, where a hot water supply request is awaited. When the hot water tap 23 is opened in this state, the hot water supply heat exchanger 5 is heated by the heat retaining operation, so that the hot water discharged from the hot water supply heat exchanger 5 is close to the target temperature on the high temperature side. Therefore, hot water having a temperature close to the target hot water supply temperature Ts desired by the user is supplied from the hot water tap 23.

When the warming operation is performed, it is confirmed that the hot water supply history flag is "1". If the hot water supply history flag is not “1”, it indicates that hot water has not been supplied since the start of operation, there may be no hot water in the hot water supply heat exchanger 5, and there is a risk of empty heating. It is forbidden.

On the other hand, steps 5, 6, and 7 are repeated.
When there is no request for additional cooking for a minute, it is expected that the temperature of the hot water in the hot water supply heat exchanger 5 has dropped due to natural cooling. Therefore, repeat steps 5, 6 and 7, and if there is no additional cooking request for 5 minutes,
The process proceeds from step 7 to step 8, and the same heat retaining operation as described above is performed. Referring to the timing chart of FIG. 4, assume that there is again a hot water demand at t ₅ (step 9), the hot water supply combustion stops at t ₆ (Step 3), leading to t ₇ has elapsed 5 minutes In this case, the hot water supply burner 13 is burnt in a pulsed manner for the time T ₁ , which is the interval time T.
_{The process} is repeated twice with 2 interposed therebetween, and the hot water supply heat exchanger 5 is heated. Therefore, when the hot-water tap 23 is opened in this state, the high-temperature hot water discharged from the hot-water supply heat exchanger 5 is close to the target temperature on the high-temperature side, and the hot-water tap 23 reaches the target hot water temperature Ts desired by the user. Hot water of near temperature is supplied.

In the above embodiment, the heat retention operation is forcibly performed when a certain time has elapsed from the stop of hot water supply or when there is a request for additional cooking, but prior to the burner combustion in the heat retention operation. It is also recommended to provide a function for determining whether or not the heat retaining operation is necessary.

In other words, starting from the fact that the elapse of 5 minutes has been confirmed in step 7 or the fact that an additional cooking instruction has been issued in step 6, the water temperature in the hot water supply heat exchanger 5 is reduced to the required reference temperature. It is determined whether it has decreased to the following. Specifically, the detection output of the hot water temperature sensor 32 is taken in, and based on this detection output, whether the temperature Th of the hot water discharged from the hot water supply heat exchanger 5 satisfies the condition of the following equation (1). Determine whether or not.

Th ≧ Ths−ΔT (1) where Ths = (1 + β) Ts−βTc where Ts is a target hot water supply temperature set by the operation unit 50,
Ths is a target value of the hot water temperature in the heat exchanger 2 (up to 80 ° C. at maximum), Tc is the incoming water temperature detected by the incoming water temperature sensor 30, and β is the hot water supply heat exchanger 5 and the bypass 2
8, ΔT is a temperature allowable value (for example, ΔT =
3 ° C.).

If the condition of the above-mentioned equation (1) is satisfied, the temperature of the hot water in the hot water supply heat exchanger 5 is slightly reduced, so that the heat keeping heating is not performed. On the other hand, if the condition of the expression (1) is not satisfied and Th <Ths−ΔT, the temperature of the hot water in the hot water supply heat exchanger 5 greatly decreases. together to open the valve 8, 9, 10, the gas proportional valve 15 to ignite the hot water supply burner 13 is set to a predetermined opening degree, heating controls the hot water supply heat exchanger 5 for a predetermined time T _1.

After the combustion heating, the solenoid valves 8, 9 and 10 are closed and the combustion is controlled to stop for a predetermined interval time T ₂ , and then the hot water supply heat exchanger 5 is operated based on the detection output of the high temperature hot water temperature sensor 32. Is checked. At this time, if Th <Ths−ΔT, the controller 50 again controls the solenoid valves 8 and 8 of the hot water supply burner 13.
9,10 to open the igniting the hot water supply burner 13 by heating control the heat exchanger 5 for hot water for a predetermined time T _1.

As a result of continuing the intermittent combustion control of the heat exchanger 2 as a result, if Th ≧ Ths−ΔT, the above-mentioned heat-retaining heating is stopped. As soon as the temperature of the hot water falls and Th <Ths-ΔT, the warming and heating is resumed.

In the above intermittent combustion, the hot water supply burner 1
3 is burnt time T ₁ and non-burning interval time T
₂ is determined as follows.

For example, the burning time T ₁ is set to a fixed constant value (for example, 5 seconds), and the interval time T ₂ is set between the incoming water temperature Tc based on the detection output of the incoming water temperature sensor 30 and the target hot water supply temperature Ts. It is changed based on a certain relational expression according to the deviation (Ts-Tc). Alternatively, in both the combustion time T ₁ and the interval time T ₂ , the deviation (Ts−Tc) between the incoming water temperature Tc and the target hot water supply temperature Ts.
In accordance with a certain relational expression. further,
The combustion is continued until the hot water temperature Th reaches a predetermined temperature (for example, Ths + ΔT) without fixing the burning time T ₁ , while the interval time T ₂ is a time interval between the incoming water temperature Tc and the target hot water supply temperature Ts. It may be changed based on a constant relational expression according to the deviation (Ts-Tc).

In the above-described embodiment, the warming operation is performed irrespective of the user's intention. However, for example, a warming switch is provided, and the warming operation is performed only when this switch is ON. Is also good. It is also possible to timer-manage the heat retention operation request time set by the user, and to output a heat retention command by the timer.

Further, in the present embodiment, the tapping hot water temperature sensor 32 is provided at the outlet side of the hot water supply heat exchanger 5 in order to detect the hot water temperature of the hot water supply heat exchanger 5. It is also possible to provide a dedicated temperature sensor in the middle of the duct of the vessel 5 so that the temperature of the hot water in the hot water supply heat exchanger 5 can be more accurately grasped.

In the above-described embodiment, the intermittent combustion is described as an example of the heat retention and heating. However, the present invention is not limited to this, and the ignition area of the burner can be adjusted,
In some cases, continuous combustion is performed by a method such as reducing the amount of gas. The heating and heating need not be performed by a burner. For example, a heater may be attached to the outer wall of the heat exchanger 5 for hot water supply, and the heating and heating may be performed using the heater. This heater may be provided exclusively for determining the presence or absence of hot water in the hot water supply heat exchanger 5, but may also be used as a freeze prevention heater.

In the present embodiment, the water heater 1 is of the bypass mixing type, but is not limited to this.

As a method for checking the presence or absence of hot water in the heat exchanger, in addition to the method for indirectly checking the presence or absence of hot water in the heat exchanger based on the presence or absence of the tapping operation as described above, A method is also possible in which a pressure sensor or a pressure switch is connected to a nearby hot water flow path via a pressure guiding pipe to detect pressure due to the presence (water level) of hot water.

[0045]

According to the water heater of the present invention, the warming operation of the heat exchanger for hot water supply is performed in response to the additional cooking instruction. As a result, the cooling of the hot water in the hot water supply heat exchanger due to the ventilation at the time of additional cooking is prevented, and the temperature of the hot water in the hot water supply heat exchanger is kept within the target value. Therefore, the hot water heater of the present invention has an effect that hot water close to a desired temperature is immediately discharged regardless of the timing of hot water supply at any time.

The water heater according to the second aspect of the invention takes into account both forced cooling by the air supply fan and natural cooling caused by the passage of time, and it is desirable to supply a hot water at any time. There is an effect that hot water close to the temperature is immediately discharged.

Further, the water heater according to the third and fourth aspects has an effect of preventing the hot water supply heat exchanger from being idle, and has an effect of high safety and durability.

[Brief description of the drawings]

FIG. 1 is a piping system diagram of a forced water supply / exhaust water heater having both a heat exchanger for post-bath cooking and a heat exchanger for hot water supply.

FIG. 2 is a configuration diagram of an air supply case having a structure different from the structure adopted in FIG. 1;

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

FIG. 4 is a timing chart showing control of the water heater according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hot-water supply device 2 Hot-water supply case 3 Heat exchanger for after-heating bath 5 Heat exchanger for hot-water supply 11 Air supply fan

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Eiichi Tsuji 93, Edocho, Chuo-ku, Kobe-shi, Hyogo Pref.

Claims (4)

[Claims] 1. A heat exchanger for bath heating and a heat exchanger for hot water supply are provided together, and the heat exchanger for bath heating and heating is heated in response to a heating instruction and heat exchange for hot water supply in response to a hot water supply instruction. The hot water is heated and discharged from the hot water supply heat exchanger. When there is no hot water from the hot water supply heat exchanger, the heat retaining operation is performed to keep the hot water supply heat exchanger warm and keep the hot water in the hot water supply heat exchanger. A hot water heater characterized in that a warming operation of a heat exchanger for hot water supply is performed in response to an additional cooking instruction. 2. A heat exchanger for hot-water supply according to a hot-water supply command, wherein the heat exchanger for hot-water supply and a heat exchanger for hot-water supply are both provided. The hot water is heated and discharged from the hot water supply heat exchanger. When there is no hot water from the hot water supply heat exchanger, the heat retaining operation is performed to keep the hot water supply heat exchanger warm and keep the hot water in the hot water supply heat exchanger. In the hot water heater, the warming operation is performed starting from the earlier of the time when the additional heating instruction is given or the predetermined time has elapsed after the hot water supply from the hot water supply heat exchanger is stopped. A water heater characterized by the following. 3. Prior to the heat retaining operation, the existence state of the hot water in the heat exchanger is examined, and when the hot water is present at a required amount or more, the warming operation can be executed. The water heater according to claim 1 or 2, wherein execution of the warming operation is prohibited. 4. The apparatus according to claim 3, wherein the means for checking the presence / absence of hot water in the heat exchanger is performed by checking whether or not a hot water discharging operation has been performed before executing the heat retaining operation. Water heater.