JPH1137556A - Hot-water supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot-water supply which enables the supply of hot water of near the desired temperature as fast as possible at the start of the hot-water supply and the rise of the internal pressure of the heat exchanger can be avoided with the hot-water supply heated by the combustion with a burner. SOLUTION: In a hot-water supply provided with a water heating heat exchanger 2 heating water supplied through water inlet duct 5 by the combustion at the burner 3 and outputs it through a hot-water outlet duct 6, a controlling means H executing a normal combustion control by starting the combustion at a burner 3 along with the start of the water supply to the heat exchanger 2 and stopping the combustion at the burner 3 along with the stopping of the water supply to it, the controlling means H starts the combustion at the burner 3 when the setting condition of the starting thermally insulating combustion is satisfied and executes the control of the thermally insulating combustion combusting intermittently at the burner 3 by the time setting condition for stopping the thermally insulating combustion is satisfied at the state of water flow to the heat exchanger 2 is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger for heating water supplied from a hot water supply line by heating water supplied through a water supply passage by burning a burner, and starting water flow to the heat exchanger. And a control means for executing normal combustion control for starting the combustion of the burner as the water is supplied and stopping the combustion of the burner as the flow of water is stopped.

[0002]

2. Description of the Related Art Such a hot water supply apparatus is conventionally known. After the tapping of hot water by the normal combustion control is stopped, the flow of water to the heat exchanger is restarted, and the normal combustion control is executed again. Until the hot water is started, the burner is kept in the combustion stopped state. However, in such a configuration, when the time from when the hot water is stopped to when the hot water is started again becomes long, the temperature of the heat exchanger heated by the burner decreases. There is a disadvantage in that it takes time to heat the heat exchanger whose temperature is lowered and the temperature of the heat exchanger is lowered by the burner to raise the temperature of the hot water to the desired temperature.

[0003] Therefore, a circulation path is formed by connecting the water inlet path and the hot water path, and in a state where the hot water is stopped and the burner is not burning, the heat exchanger is intermittently driven by the circulation pump through the circulation path. In order to keep the temperature of the hot water in the heat exchanger as close as possible to the desired temperature, it has been proposed to make the hot water flow in the heat exchanger by intermittently burning the burner. -116237).

[0004]

However, the one disclosed in the above publication requires a special piping and a circulating pump for forming a circulating path, and has a disadvantage of increasing the number of parts and increasing the cost. . Therefore, in order to eliminate such disadvantages, the present applicant, in a state in which the flow of water to the heat exchanger is stopped, starts burning the burner when the set condition for starting the warming combustion is satisfied, and stops the warming combustion. Filed a hot water supply device with a so-called hot water function, in which a heat retention combustion control for stopping the combustion of the burner when the set conditions for use were satisfied and keeping the temperature of the hot and cold water in the heat exchanger close to a desired temperature. (For example, Japanese Patent Application No. 8-164098).

However, in the hot water supply apparatus of the above application,
If the set conditions for starting the warming combustion are satisfied and the combustion of the burner is started, the burner is continuously burned until the setting conditions for stopping the warming combustion are satisfied. There was a problem that the internal pressure inside the vessel increased abnormally. For example, when the temperature of the hot water in the heat exchanger is extremely low, such as in the morning, the burner is continuously burned to raise the hot water temperature in the heat exchanger to near the desired temperature. Then, since the hot water stays in the heat exchanger, the hot water in the heat exchanger is locally heated and boiled, thereby increasing the internal pressure of the heat exchanger and adversely affecting the heat exchanger. There was a problem, and there was room for improvement in this regard.

The present invention has been made in view of this point, and an object of the present invention is to supply hot water having a temperature close to a desired temperature as quickly as possible at the start of tapping while avoiding an increase in the number of parts. It is another object of the present invention to provide a hot water supply device which can perform the heat treatment locally and can prevent the internal pressure of the heat exchanger from being locally increased by the burner and raised as much as possible.

[0007]

According to the first aspect of the present invention, there is provided a hot water supply system comprising a control unit for executing a normal combustion control for burning a burner based on the flow of water to a heat exchanger. In the device, the control means starts combustion of the burner when a set condition for starting warmed combustion is satisfied in a state where water flow to the heat exchanger is stopped, and sets a set condition for stopping warmed combustion. Is performed so as to intermittently burn the burner until is satisfied. Therefore, the circulation path and the circulation pump as in the conventional configuration described above are unnecessary, and the configuration is not complicated.
Hot water at a temperature close to the desired temperature can be supplied as quickly as possible at the start of tapping. In addition, in the insulated combustion control, until the set condition for stopping the insulated combustion is satisfied,
Since the burner is intermittently burned, the intermittent combustion makes it possible to equalize the temperature of the hot water in the heat exchanger, even if the temperature of the hot water in the heat exchanger is extremely low. Even so, it is possible to prevent boiling due to local heating and avoid problems associated with an increase in heat exchanger internal pressure.

According to the second aspect of the present invention, there is provided a hot water temperature detecting means for detecting a temperature of hot water in the hot water path or the heat exchanger, and the control means detects the hot water temperature by the hot water detecting means. When the value becomes equal to or less than the set lower limit value, it is determined that the set condition for the start of the warming combustion is satisfied. Therefore, when the hot water is stopped and the temperature of the heat exchanger falls, and the temperature of the hot water in the hot water path or the heat exchanger falls below the set lower limit, combustion of the burner in the warming combustion control is started. The hot water in the hot water path or the heat exchanger that first flows out at the time of hot water re-starting does not reach a low temperature equal to or lower than the set lower limit value, and the hot water is started at a desired temperature or a temperature close thereto as much as possible.

According to a third aspect of the present invention, the control means is arranged such that the detected value of the hot water temperature detecting means is equal to or less than the set lower limit, and a temperature difference from the set lower limit is equal to or more than the set temperature difference. In this case, the burner is intermittently burned, and if the temperature is less than the set temperature difference, the burner is continuously burned without intermittently burning to execute the heat retention combustion control. . Therefore, by appropriately setting the set temperature difference, when the temperature of the hot and cold water in the heat exchanger is significantly reduced, the burner is intermittently burned to suppress an increase in the internal pressure of the heat exchanger. On the other hand, when it is not necessary to perform intermittent combustion, it is possible to terminate the warming combustion control in a short time by continuous combustion, and it is possible to more reliably discharge hot water at a desired temperature or a temperature close to it at the start of hot water discharge.

According to the fourth aspect of the present invention, there are provided a combustion amount adjusting means capable of changing the combustion amount of the burner and a target temperature setting means capable of changing and setting the target temperature for tapping. Is configured to control the combustion amount adjusting means in the normal combustion control so that the tap water temperature becomes the target temperature, and in the insulated combustion control, the set lower limit is changed as the target temperature is changed. It is configured to change the value. Therefore, when the hot water is supplied from the hot water supply path and the normal combustion control is being performed, the burner combustion amount is adjusted so that the hot water temperature is controlled to an arbitrarily set target temperature. become. Then, when the hot water is stopped and the warming combustion control is executed, if the target temperature has been changed, the set lower limit value is changed in accordance with the target temperature, whereby the warming is maintained by the warming combustion control. The temperature of the hot water that flows first at the time of tapping can be set to the changed target temperature or a temperature close thereto.

According to a fifth aspect of the present invention, when the detected value of the hot water temperature detecting means is equal to or more than a set upper limit, the control means determines that the set condition for stopping the warm combustion is satisfied. It is configured to be. Therefore, it is possible to reliably prevent the temperature of the hot water that flows first at the time of re-hot water from rising to an unnecessarily high temperature exceeding the set upper limit value, and to supply the hot water having the desired temperature or a temperature close thereto as quickly as possible. Become.

According to the invention described in claim 6, the control means stops the combustion of the burner and burns the burner intermittently every time the temperature of the hot water in the heat exchanger rises by a predetermined temperature. It is configured as follows. Therefore, for example, it is easier to make settings for avoiding local boiling than in the case of intermittent combustion by stopping the combustion of the burner every time a predetermined time elapses, and to more reliably prevent the internal pressure of the heat exchanger from rising. be able to.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a hot water supply apparatus according to the present invention will be described. As shown in FIG. 1, the hot water supply apparatus includes a hot water supply unit K for heating supplied water to supply hot water to a hot water tap (not shown), a control unit H as control means for controlling the operation of the hot water supply unit K, The unit H is provided with a remote control operation unit R for instructing operation information to the unit H.

The hot water supply unit K includes a heat exchanger 2 for heating water, a gas-fired burner 3 for heating the heat exchanger 2, and a combustion air flowing through the burner 3 in the combustion chamber 1. The heat exchanger 2 is provided with a fan 4 and the like that can change and adjust the amount of ventilation, and the heat exchanger 2 is supplied with water from a domestic water supply or the like, for example, and receives hot water from a hot water tap. The hot water outlet paths 6 are connected to each other, and a hot water temperature thermistor 7 as hot water temperature detecting means YK for detecting the temperature of hot water in the heat exchanger 2 is provided. The water inlet channel 5 is provided with a water flow amount sensor 8 for detecting the amount of water flowing to the heat exchanger 2 and an incoming water temperature thermistor 9 for detecting the incoming water temperature. A tap water temperature thermistor 10 as YK is provided.

A fuel supply passage 11 for the burner 3 is provided with an electromagnetically operated on-off valve 12 for intermitting fuel supply, and an electromagnetically operated type as a combustion amount adjusting means capable of changing and adjusting a fuel supply amount (a combustion amount of the burner 3). In the vicinity of the burner 3, an igniter 14 for executing an ignition operation for the burner 3 and a frame rod 15 for detecting whether or not the burner 3 is ignited are provided. .

The remote control operation unit R includes an operation switch 16 for instructing start / stop of the operation of the hot water supply unit K, a temperature setting switch 17 as target temperature setting means capable of changing and setting a target temperature Ts for tapping, and a tapping temperature. The display 18 includes a display unit 18 for displaying the temperature and a target temperature, an operation lamp 19 for displaying an operation state, a combustion lamp 20 for displaying that the burner 3 is in a combustion state, and the like.

The control section H is provided with a microcomputer, and includes a normal combustion control means 100 for executing normal combustion control during hot water supply, and a warm combustion control means 101 for executing warm combustion control during hot water supply standby. It is provided in the form of a control program.

The normal combustion control means 100 includes a hot water supply section K
Is in the operating state, the combustion of the burner 3 is started as the flow of water to the heat exchanger 2 is started, and the combustion of the burner 3 is started as the flow of water to the heat exchanger 2 is stopped. And the normal combustion control for adjusting the combustion amount of the burner 3 so that the hot water supply temperature becomes the target temperature Ts when the flow of water to the heat exchanger 2 is detected. It is configured.

Specifically, after the operation state is set in accordance with the ON operation of the operation switch 16 and the water flow detected by the water flow sensor 8 exceeds the set water flow in response to the opening operation of the hot water tap. Then, the ventilation operation by the fan 4 is started, the intermittent valve 12 is opened, and the gas amount control valve 13 is opened and adjusted to the ignition gas amount, and the igniter 14 ignites the burner 3 to fire the flame rod. Confirm by 15.
And the incoming water temperature thermistor 9, the outgoing water temperature thermistor 10,
Based on the detection information of each of the water flow rate sensors 8 and the information of the target temperature Ts set by the temperature setting switch 17, the amount of combustion of the burner 3 required to bring the hot water supply temperature to the target temperature Ts is calculated. The gas amount control valve 13 is adjusted and controlled so as to obtain a gas amount corresponding to the obtained combustion amount, and the fan 4 is controlled so that the ventilation amount of the fan 4 is in an appropriate combustion state with respect to the adjusted gas amount. The ventilation amount is adjusted and controlled. In this way, the target temperature T
s of hot water will be supplied.

In the standby state in which the hot water supply is stopped, that is, in the state in which the flow of water to the heat exchanger 2 is stopped, the insulated combustion control means 101 burns the burner when the set condition for starting the insulated combustion is satisfied. 3 is configured to start the combustion of the burner 3, and to execute the warm combustion control for stopping the combustion of the burner 3 when a set condition for stopping the warm combustion is satisfied. More specifically, in a state where the flow of water to the heat exchanger 2 is stopped, if the detected value of the hot water temperature thermistor 7 becomes equal to or less than the set lower limit, the set condition for the start of the warming combustion is satisfied. When it is determined, the combustion of the burner 3 is started, and when the detected value of the hot water temperature thermistor 7 becomes equal to or more than the set upper limit, it is determined that the set condition for stopping the heat retaining combustion is satisfied, and the combustion of the burner 3 is stopped. It is configured as follows. In addition, you may comprise so that heat retention combustion control may be performed based on the detection value of the tapping water temperature thermistor 10.

In this warming combustion control, for example, when the temperature of the hot water in the heat exchanger 2 is reduced to near the temperature of the supply water, such as at the start of the first operation in the morning,
When the detected value of the hot water thermistor 7 is equal to or less than the set lower limit value,
When the temperature difference from the set lower limit value is equal to or larger than the set temperature difference, the burner 3 is configured to perform the combustion intermittently in a plurality of times. In this way, in the hot water supply standby state, it is possible to prevent the temperature of the hot water in the hot water path inside the hot water supply device from dropping, to discharge the hot water of the target temperature as quickly as possible at the time of hot water renewal, and to exchange heat as in the first time in the morning. When the temperature of the hot water in the heat exchanger 2 is extremely low, the combustion of the burner 3 is divided into a plurality of times and the fuel is burned stepwise, and the hot water stays in the heat exchanger 2. The hot water in the heat exchanger 2 is configured to be locally boiled to avoid problems such as an increase in internal pressure.

The hot water temperature thermistor 7 is provided in a portion of the hot water passage in the heat exchanger 2 which is easily heated by the combustion of the burner 3 and in which the hot water temperature is liable to decrease during standby for hot water supply. That is, as shown in FIG. 2, the heat exchanger 2 is in a state in which a plurality of fin tube type heat exchange pipe sections 2a are vertically stacked, and extends over the left and right side walls 1A and 1B constituting the combustion chamber 1. , And are connected to each other by a plurality of U-shaped tubes 2b on the outer sides of the left and right side walls 1A and 1B so that they form a series of lines connected in a meandering manner. I have. And
The hot water thermistor 7 is provided in the U-shaped tube 2b located near the heat exchange pipe portion 2a located on the lower side of the U-tube 2b.

Next, the control operation of the control unit H will be described with reference to the control flowchart shown in FIG. When the power is turned on to the hot water supply device and the operation switch 16 is not turned on, the heat retention flag is set to the "OFF" state and the operation is on standby (steps 1 and 2). Then, after the operation switch 16 is turned on, the detection value of the water flow rate sensor 8 exceeds the set water flow rate as the hot water tap is opened, and water flow (water flow) to the heat exchanger 2 is detected. Then, the normal combustion control is executed. In other words, the burner 3 is ignited, and the combustion amount of the burner 3 and the ventilation amount of the fan 4 are controlled such that the tapping temperature detected by the tapping temperature thermistor 10 becomes the target temperature Ts set by the temperature setting switch 17. (Steps 3-5).

This normal combustion control is performed when the hot water tap is closed and no water flow is detected, or when the operation switch 16
Is executed until the is turned off (Step 6,
7). It should be noted that even if the operation switch 16 is turned on in step 1, if the water flow is not detected, it is determined whether or not the heat retention flag is set to the "ON" state. Step 12) Since the heat retention flag is set to the "OFF" state at the initial stage of the installation of the apparatus, the process returns to step 1 to be in a standby state until a water flow is detected. In this way, at the initial stage of the installation of the apparatus, the heat retention combustion control is not executed.

When the hot-water tap is closed and the detection value of the water flow rate sensor 8 falls below the set water amount during the normal combustion control, the combustion of the burner 3 is stopped and the heat retention flag is turned on. (Steps 6, 8,
9) Standby state until water flow is detected. When the normal combustion control is being executed, the operation switch 16
Is turned off, the combustion of the burner 3 is stopped, and the heat retention flag is set to the "OFF" state (steps 7, 10, 11), and a standby state is set until the operation switch 16 is turned on.

Therefore, when the operation switch 16 is turned on and the normal combustion control based on the detection of the water flow is executed, the water flow is not detected and the combustion of the burner 3 is stopped. ON state, and the operation switch 16 is turned off.
When operated, or even when the operation switch 16 is turned ON, if the water flow is not detected even once,
The heat retention flag is set to “OFF”. When the operation switch 16 is ON and the water flow is not detected, and the heat retention flag is set to the “ON” state, the detection value Tx based on the detection information of the hot water temperature thermistor 7 is used. Is determined to be equal to or lower than a set value (set lower limit) SK lower than the set temperature α by a set amount α (steps 12 and 13), the warm combustion by the burner 3 is started.

The warming combustion starts when the detected value Tx of the hot water thermistor 7 falls below the set lower limit SK, as described above. However, as shown in FIG. If the temperature difference from the value SK is equal to or larger than the set temperature difference, the combustion of the burner 3 is started, and the combustion of the burner 3 is temporarily stopped after the detection value Tx detected by the hot water temperature thermistor 7 increases by 10 degrees Celsius ( Steps 14-17). Then, after waiting for a set time (for example, two or three minutes) to elapse (step 18), the detected value Tx of the hot water temperature thermistor 7 is higher than the target temperature Ts by the set amount β (set upper limit value).
When it is determined that the above has been reached (step 22), the heat-retention combustion control is terminated. If the temperature is below the set upper limit, the temperature difference between the detected value Tx of the hot water temperature thermistor 7 and the set lower limit SK is set again. It is determined whether or not the temperature difference is exceeded. If the temperature difference is not less than the set temperature difference, the burner 3 burns and the heat exchanger 2
The temperature of the hot water inside is raised by 10 degrees Celsius.

As described above, the detection value Tx of the hot water temperature thermistor 7
Is smaller than or equal to the set lower limit SK, and if the temperature difference between the detected value Tx of the hot water temperature thermistor 7 and the set lower limit SK is equal to or larger than the set temperature difference, the burner 3 is intermittently burned in a plurality of times, The temperature of the hot water in the heat exchanger 2 is increased by 10 degrees Celsius,
When the detected value Tx of the hot water temperature thermistor 7 becomes equal to or more than the set upper limit value, the warming combustion control ends. In addition, hot water thermistor 7
If the temperature difference between the detected value Tx and the set lower limit value SK is smaller than the set temperature difference, the combustion of the burner 3 is started and the combustion is continued until the detected value Tx of the hot water temperature thermistor 7 becomes equal to or more than the set upper limit value. (Steps 19, 22, 23). In this manner, warm combustion is performed. At this time, when the hot-water tap is opened and a water flow is detected, the process proceeds to step 5 to execute normal combustion control (step 20), and the operation switch 16 is turned on by the operation switch 16.
When the FF operation is performed, the heat retention flag is set to the “OFF” state, and the heat retention combustion of the burner 3 is stopped (step 21,
24, 25).

The lower limit set as the condition for starting the warming combustion is a temperature lower than the target temperature Ts for tapping by a set amount α, and the upper limit set as the stop condition is a temperature higher than the target temperature Ts by a set amount β. Therefore, when the target temperature Ts is changed and set based on the operation of the temperature setting switch 17, the set lower limit value and the upper limit value are changed accordingly, and the target temperature Ts is set in the hot water path inside the apparatus. Hot water is the target temperature Ts
Is kept at a temperature close to the temperature. The set amounts α and β are appropriately set according to the characteristics of the water heater, and may be different values or may be set to the same value. Further, the set amounts α and β may be automatically changed with the change of the target temperature Ts.

In the hot water supply standby state in which the hot water supply is stopped, the hot and cold water in the pipeline inside the heat exchanger 2 is always kept at the target temperature Ts or a temperature close to the target temperature Ts. Hot water having the target temperature Ts or a temperature close to the target temperature Ts is supplied as soon as possible, which makes it easy to use. In addition, when the temperature of the hot water in the heat exchanger 2 is extremely low, such as the first in the morning, the heat-retention combustion is performed in multiple stages in a stepwise manner, and the local boiling of the hot water in the heat exchanger 2 is performed. Can be prevented from increasing due to the internal pressure.

[Another Embodiment] (1) In the above embodiment, the water inlet 5 is connected to the heat exchanger 2.
And the hot water path 6 are connected to each other, and after the entire amount of water supplied from the water inlet path 5 is heated by the heat exchanger 2, the hot water path 6
Although the configuration is such that the hot water is supplied from the hot water, the following configuration may be used instead of the above configuration.

As shown in FIG. 5, the water inlet channel 5 and the hot water channel 6 are connected via a bypass 30 bypassing the heat exchanger 2, and a bypass valve 31 is provided for connecting and disconnecting the bypass 30. An outlet hot water thermistor 32 for detecting the hot water temperature at the outlet of the heat exchanger 2 and a mixed hot water thermistor 33 for detecting the mixed hot water temperature are provided. And the bypass valve 31
When the bypass valve 31 is opened, the detection information of the outlet hot water temperature thermistor 32 and the target temperature Ts are set when the bypass valve 31 is opened. Thus, the combustion amount of the burner 3 is feed-forward controlled, and the combustion amount of the burner 3 is feedback-controlled based on the detection information of the mixed-water temperature thermistor 33 so that the mixed-water temperature becomes the target temperature Ts. In the hot water supply device having such a configuration, the outlet hot water temperature thermistor 32 may be used as the hot water temperature detecting means YK, or the hot water temperature in the heat exchanger 2 is detected as in the previous embodiment. The hot water thermistor 7 may be provided, and the hot water thermistor 7 may be used as the hot water temperature detecting means YK.

At the junction of the bypass path 30 and the tapping path 6, a mixing valve whose distribution ratio can be changed and adjusted is provided, and in normal combustion control, the detection value of the outlet hot water thermistor 32 is set to a set temperature (for example, 80 ° C.). ), The combustion amount of the burner 3 may be adjusted, and the mixing ratio of the mixing valve may be adjusted and controlled so that the mixed hot water temperature becomes the target temperature.

(2) In the above embodiment, the hot water temperature detecting means Y
Only when the temperature difference between the detected value Tx of K and the set lower limit value SK is equal to or larger than the set temperature difference, the heat-retention combustion by the burner 3 is configured to be performed intermittently in a plurality of times. Even if the temperature difference between the detection value Tx of the detection means YK and the set lower limit value SK is smaller than the set temperature difference, the heat-retention combustion is performed intermittently in a plurality of times. The combustion may be configured to be performed intermittently. In that case, the number of times of burning of the burner 3 in the warming combustion control can be changed as appropriate. In the above-described embodiment, when the target temperature Ts is changed, the set lower limit value is changed. Is configured to automatically change the number of times the burner 3 burns.
Further, in the above embodiment, the combustion of the burner 3 is temporarily stopped every time the detection value Tx detected by the hot water temperature detection means YK rises by 10 degrees Celsius. However, the stop temperature is not limited to every 10 degrees Celsius, but may vary. And the stop time can be changed. Furthermore, instead of causing the burner 3 to intermittently burn due to a rise in temperature, the burner 3 is stopped at regular intervals and intermittently burns. It can also be configured.

(3) In the above embodiment, the hot water temperature detecting means Y
When the detected value Tx of K becomes equal to or lower than the set lower limit value, the insulated combustion is started, and when the detected value Tx of the hot water temperature detecting means YK becomes equal to or more than the set upper limit value, the insulated combustion is stopped. If the set time has elapsed since
It is good also as composition which starts warm combustion and stops warm combustion after a set time passes from the start of warm combustion.
Further, the configuration may be such that when the detected value Tx of the hot water temperature detecting means YK becomes equal to or less than the set lower limit value, the insulated combustion is started, and the insulated combustion is stopped when a set time has elapsed from the start of the insulated combustion. Conversely, when the set time elapses after the normal combustion is stopped, the warm combustion is started, and the hot water temperature detecting means YK
When the detected value Tx is equal to or larger than the set upper limit, the warm combustion may be stopped.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a water heater.

FIG. 2 is a perspective view of a heat exchanger.

FIG. 3 is a flowchart of a control operation.

FIG. 4 is a flowchart of a control operation.

FIG. 5 is a schematic configuration diagram of a hot water supply unit of another embodiment.

[Explanation of symbols]

 2 Heat exchanger 3 Burner 5 Inlet channel 6 Outlet channel 13 Burning amount adjusting means 17 Target temperature setting means H Control means YK Hot water temperature detecting means

Claims (6)

[Claims] 1. A water heating heat exchanger for heating water supplied through a water inlet channel by burning a burner and tapping the hot water from a hot water outlet channel; Control means for performing normal combustion control for starting combustion of the burner and stopping the combustion of the burner as the flow of water is stopped, the control means comprising: In a state in which the flow of water to the heat exchanger is stopped, the combustion of the burner is started when a set condition for starting warmed combustion is satisfied, and the burner is intermittently turned on until the set condition for stopping warmed combustion is satisfied. A hot-water supply device configured to execute heat-retention combustion control for performing specific combustion. 2. A hot water temperature detecting means for detecting a temperature of hot water in the hot water path or the heat exchanger, wherein the control means, when a detection value of the hot water temperature detecting means becomes equal to or less than a set lower limit, The hot water supply apparatus according to claim 1, wherein the hot water supply apparatus is configured to determine that the set condition for starting the warming combustion is satisfied. 3. The control means intermittently turns off the burner when a detection value of the hot water temperature detection means is equal to or less than the set lower limit and a temperature difference from the set lower limit is equal to or more than the set temperature difference. The hot water supply apparatus according to claim 2, wherein, when the temperature is less than the set temperature difference, the burner is continuously burned without intermittently burning to execute the heat keeping combustion control. 4. 4. A combustion amount adjusting means capable of changing the combustion amount of the burner, and a target temperature setting means capable of changing and setting a target temperature for tapping, wherein the control means includes: It is configured to control the combustion amount adjusting means so that the tap water temperature becomes the target temperature. In the insulated combustion control, the set lower limit value is changed as the target temperature is changed. The hot water supply device according to any one of claims 2 to 3, wherein the hot water supply device is provided. 5. The control means is configured to determine that the set condition for stopping the warming combustion is satisfied when a detected value of the hot water temperature detecting means is equal to or more than a set upper limit value. The hot water supply device according to any one of claims 1 to 4. 6. The control device according to claim 1, wherein the control unit stops the burner combustion and burns the burner intermittently every time the temperature of the hot water in the heat exchanger rises by a predetermined temperature. The hot water supply apparatus according to any one of claims 1 to 5.