JP7746234B2 - Storage-type hot water heater - Google Patents

Description

The present invention relates to improving the operating efficiency of a storage-type hot water heater equipped with a solar power generation system.

Conventionally, hot water storage type water heaters that work in conjunction with solar power generation systems are known to use the electricity generated by the solar power generation system to efficiently heat water during the daytime.

In recent years, electricity rate plans that set the same electricity rates for daytime and nighttime (late night) hours have become known for users who install solar power generation systems and hot water storage systems. Hot water storage systems that are linked to solar power generation systems perform heating operation using electricity generated by the solar power generation system during the daytime when the sun is up, and also perform heating operation during the daytime when the sun is not up at the same electricity rate as heating operation during the nighttime (late night).This means that daytime operation hot water storage systems are known that can reduce electricity bills by using electricity generated by the solar power generation system to heat water during the daytime when the sun is up, thereby reducing electricity bills.

Furthermore, as in Patent Document 1, in a storage-type hot water supply system with a solar power generation system that performs heating operation during the daytime, even if hot water is needed before the daytime heating operation (for example, early in the morning), there is a possibility that sufficient hot water may not be secured before the heating operation begins, so a control method has been known in which a small amount of hot water is heated during the night (late at night).

JP 2022-67381 A

However, with this type of daytime operation storage-type hot water heater, there is a method of heating a small amount of water at night to ensure hot water is available before the daytime heating operation. However, during times when not much hot water is used, the amount of water heated by solar power generation is reduced, resulting in a poor daytime heating operation rate, which is an issue.

Furthermore, if nighttime heating operations were simply reduced in order to increase the daytime heating operation rate, there was the issue that if the hot water in the hot water storage tank was used before the daytime heating operation, the hot water would run out depending on the amount of usage. Therefore, improving the daytime heating operation rate and reducing the risk of running out of hot water were issues to be addressed.

The hot water storage type hot water heater of the present invention comprises a hot water storage tank for storing hot water, a heating means capable of heating the hot water using privately generated electricity obtained from a solar power generation system, a control device for controlling the heating operation in which the heating means heats the hot water in the hot water storage tank, a target boiling amount calculation means for calculating a target boiling amount to be heated by the end of the daytime period of the next day based on the amount of hot water storage required for the next day, and a specific amount of hot water stored in the hot water storage tank before the start of the daytime period for the period from before the start of the daytime period to before the end of the daytime period. In a hot water storage type hot water supply device equipped with a nighttime boiling amount calculation means for calculating a nighttime boiling amount that boils a portion of the target boiling amount before the start time of the daytime period so that the amount of hot water used is equal to or greater than the amount based on past usage records for that period, the control device is provided with a demand determination means that determines whether the nighttime boiling amount needs to be boiled before the start time of the daytime period, and if the demand determination means determines that boiling is not necessary, the control device does not perform boiling operation before the start time of the daytime period regardless of the set nighttime boiling amount.

The control device is also capable of acquiring the detection value of an outdoor air temperature sensor that detects the outdoor air temperature. If the outdoor air temperature is equal to or higher than a predetermined outdoor air temperature and the amount of hot and cold water based on past usage during the specified period is equal to or lower than a predetermined amount, the demand determination means determines that heating is not necessary, and the control device does not perform heating operation before the start of the daytime period.

The control device is also capable of acquiring the detection value of a water supply temperature sensor that detects the water supply temperature. If the water supply temperature is equal to or higher than a predetermined water temperature and the amount of hot water based on past usage during the specified period is equal to or lower than a predetermined amount, the demand determination means determines that heating is not necessary, and the control device does not perform heating operation before the start of the daytime period.

In the storage-type hot water supply device of the present invention, when the demand determination means determines that the demand for hot water is low, the control device does not perform nighttime boiling operation regardless of the nighttime boiling amount calculated by the nighttime boiling amount calculation means, and instead increases the boiling amount during the day, thereby reducing the risk of running out of hot water and improving the daytime boiling operation rate.

1 is a system configuration diagram of a hot water supply system including a storage type hot water supply device according to an embodiment of the present invention. A table showing the setting conditions for the end-of-boiling TH level for nighttime boiling volume. 10 is a flowchart illustrating processing executed by a nighttime boiling amount calculation means and a demand determination means. 4 is a flowchart illustrating control of the heating operation executed by the control device.

An embodiment of a hot water storage type water heater 1 according to the present invention will be described with reference to the accompanying drawings.

Figure 1 is a system configuration diagram of a hot water supply system 100 including a storage-type hot water supply device 1 in this embodiment.

The hot water supply system 100 includes a distribution board 2, a solar power generation system 3, and a storage-type hot water supply device 1 (hereinafter simply referred to as "hot water supply device 1").

The distribution board 2 is installed in a building such as a house (hereinafter simply referred to as the "house") together with the solar power generation system 3 and the hot water heater 1. The distribution board 2 is connected to the commercial power source 2a and the solar power generation system 3. The distribution board 2 supplies commercial power supplied from the commercial power source 2a and privately generated power generated by the solar power generation system 3 to the hot water heater 1 used in the house and to electrical load devices within the house other than the hot water heater 1, such as air conditioners (hereinafter simply referred to as "air conditioners, etc. 6" in the following explanation and in Figure 1).

The solar power generation system 3 includes a solar power generation panel 4 and an inverter 5. The solar power generation panel 4 is installed on the roof of a house, for example. The inverter 5 converts the power generated by the solar power generation panel 4 into AC power.

The hot water heater 1 has a hot water storage tank 7, a heat pump unit 16, a circulation circuit 24, a remote control 30, and a control device 29.

The hot water storage tank 7 stores hot water to be supplied to hot water supply terminals such as the bath and kitchen. The hot water storage tank 7 has a water supply pipe 8, a hot water outlet pipe 9, a water supply bypass pipe 10, a hot water supply pipe 12, and a hot water storage temperature sensor 15.

The water supply pipe 8 is connected to the hot water storage tank 7 at its bottom and supplies water to the hot water storage tank 7. The hot water outlet pipe 9 is connected to the hot water storage tank 7 at its top and outputs hot water from the hot water storage tank 7. The water supply bypass pipe 10 is a pipe branching off from the water supply pipe 8 and is connected to the hot water outlet pipe 9 via a mixing valve 11. The mixing valve 11 mixes the hot water from the hot water outlet pipe 9 and the water from the water supply bypass pipe 10 to reach the hot water supply temperature set by the remote control 30.

The hot water supply pipe 12 supplies hot water supplied via the mixing valve 11 to the hot water supply terminal. The hot water supply pipe 12 has a hot water supply flow rate sensor 13 and a hot water supply temperature sensor 14. The hot water supply flow rate sensor 13 detects the hot water supply flow rate and outputs a corresponding detection signal to the control device 29. The hot water supply temperature sensor 14 detects the hot water supply temperature and outputs a corresponding detection signal.

The hot water temperature sensor 15 detects the temperature of the hot water in the hot water tank 7 and outputs a corresponding detection signal to the control device 29. Multiple hot water temperature sensors 15 are installed at different height positions on the side of the hot water tank 7. When each of these hot water temperature sensors 15 detects a hot water temperature above a predetermined threshold value, which is preset to correspond to the temperature of hot water in a sufficiently heated state, it outputs a corresponding detection signal to the control device 29. The control device 29 detects the amount of hot water in the hot water tank 7 that is in a sufficiently heated state (i.e., the amount of hot water stored) based on the number of hot water temperature sensors 15 that output detection signals (here, seven sensors TH1 to TH7 are installed).

The heat pump unit 16 is a heating means that operates using privately generated electricity and commercial electricity and exchanges heat with water to boil it. The heat pump unit 16 has a compressor 17, a water-refrigerant heat exchanger 18, an expansion valve 19, an air heat exchanger 20, a refrigerant pipe 23, and a blower 21.

The compressor 17 compresses and transports the refrigerant to a high temperature and pressure. The water-refrigerant heat exchanger 18 exchanges heat between the high temperature, high pressure refrigerant and water from the hot water storage tank 7. The expansion valve 19 decompresses and expands the refrigerant that has undergone heat exchange in the water-refrigerant heat exchanger 18. The air heat exchanger 20 exchanges heat between outside air and the low pressure refrigerant, evaporating the low pressure refrigerant. The refrigerant pipe 23 circulates the refrigerant through the compressor 17, water-refrigerant heat exchanger 18, expansion valve 19, and air heat exchanger 20. The blower 21 blows outside air to the air heat exchanger 20.

The heat pump unit 16 also has a discharge temperature sensor 22 and an outside air temperature sensor 28. The discharge temperature sensor 22 detects the temperature of the refrigerant discharged from the compressor 17 and outputs a corresponding detection signal to the control device 29. The outside air temperature sensor 28 detects the outside air temperature and outputs a corresponding detection signal to the control device 29.

The circulation circuit 24 circulates the hot water in the hot water storage tank 7 between the hot water storage tank 7 and the water-refrigerant heat exchanger 18. The circulation circuit 24 has a heating supply pipe 25a, a heating return pipe 25b, a heating circulation pump 26, and a boiling temperature sensor 27.

The heating supply pipe 25a connects the bottom of the hot water storage tank 7 to the water-side inlet of the water-refrigerant heat exchanger 18. The heating return pipe 25b connects the water-side outlet of the water-refrigerant heat exchanger 18 to the top of the hot water storage tank 7. The heating circulation pump 26 is located on the heating supply pipe 25a and circulates hot water. The boiling temperature sensor 27 is located on the heating return pipe 25b and outputs a detection signal to the control device 29.

The remote control 30 accepts instructions from the user regarding the water heater 1, such as the set temperature of the hot water supplied to the water heater terminal.

The control device 29 has a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and stores various programs and data necessary for the control of the control device 29. The control device 29 controls the operation of the entire hot water supply device 1 in accordance with the various programs. The control device 29 is connected to a remote control 30 and communicates with the remote control 30 in both directions.

The control device 29 controls the heating operation to boil the hot water in the hot water storage tank 7 based on information learned from the calculation means and determination means described below and the history of hot water usage.

Next, we will explain the time periods for water heating operation. First, a day is divided into morning and afternoon periods from 7:00 to 17:00 (hereinafter simply referred to as daytime periods), nighttime periods from 17:00 to 23:00, and late-night periods from 23:00 to 7:00. The daytime water heating operation period is set to 9:00 to 17:00 (this can vary depending on the season), taking into account power generation using solar light. The nighttime water heating operation period is set to 23:00 to 7:00, a time when electricity usage is low.

This control device 29 includes a target boiling amount calculation means 31, a usage amount performance learning unit 32, a nighttime boiling amount calculation means 33, and a demand determination means 34.

The target boiling amount calculation means 31 calculates the target boiling amount, which is the total amount to be boiled from the start time (7:00 in this example) to the end time (17:00 in this example) of the daytime period, based on the amount of hot water storage required for the next day from the hot water usage history learned by the usage history learning unit 32. The control device 29 calculates the time required to perform the boiling operation during this daytime period, and controls the operation so that it is completed as late as possible. The user may also set the start or end time of the boiling operation as desired using the remote control 30.

The usage history learning unit 32 receives the detection signal from the hot water supply flow rate sensor 13 (representing the amount of hot water supplied), the detection signal from the hot water supply temperature sensor 14 (representing the hot water temperature), and the detection signal from the water supply temperature sensor (not shown) (representing the water temperature). It converts the input hot water supply amount into usage at a predetermined temperature (e.g., 43°C) while corresponding it to the hot water supply temperature. It learns the amount of hot water used by the user each day for a predetermined period in the past (e.g., seven days) and the amount of hot water used by the user during a specific period from before the start of the daytime period to before the end of the daytime period (3:00 AM to 3:00 PM in this example). The learning also includes information about hot water usage, such as whether a large amount of hot water in the hot water storage tank 7 was used during the specific period to fill the bathtub (not shown) with hot water, or whether a reheating operation was performed to heat the bathtub water by exchanging heat with the hot water in the hot water storage tank 7.

The nighttime boiling amount calculation means 33 calculates the nighttime boiling amount by boiling a portion of the target boiling amount before the start of the daytime period so that the amount of hot water stored in the hot water storage tank 7 before the start of the daytime period is equal to or greater than the amount of hot water based on the user's past usage during a specific period learned by the usage amount history learning unit 32. "Before the start of the daytime period" means the start of the daytime period (7:00 in this case), and taking into account heat dissipation from the hot water storage tank 7, it is appropriate to complete the nighttime boiling operation slightly before the start of the daytime period (approximately 6:00 to 6:30). Furthermore, although it is stated that the time is before the start of the daytime period (approximately 6:00 to 6:30), if the usage amount history learning unit 32 has learned that hot water was used earlier (at 5:00), the nighttime boiling operation may be performed earlier to catch up with the hot water usage.

In addition, if boiling operation is performed at night, the remaining boiling amount, obtained by subtracting the nighttime boiling amount from the target boiling amount, will be used as the daytime boiling amount, and boiling operation will be performed during the daytime for the daytime boiling amount.If boiling operation is not performed at night, the target boiling amount will be used as the daytime boiling amount, and boiling operation will be performed during the daytime for the daytime boiling amount (target boiling amount).

In addition, the nighttime boiling amount calculation means 33 appropriately changes and sets the end-of-boiling TH level of the hot water storage tank 7 based on the calculated nighttime boiling amount. This end-of-boiling TH indicates which of the hot water storage temperature sensors 15, TH1 to TH7, will stop boiling operation when it detects a hot water temperature above a predetermined threshold.

The details will be explained with reference to FIG.
If the usage amount record learning unit 32 has learned that there has been a history of hot water filling or reheating, the nighttime boiling amount calculation means 33 sets the boiling end TH level to level 1. In the case of level 1, as shown in the distribution of boiling amounts in Figure 2, the hot water storage temperature sensor 15 that will end the boiling operation when it detects a predetermined high temperature is selected and set from the hot water storage temperature sensors 15 installed above and below the hot water storage tank 7, in order to boil 3/7 of the target boiling amount (up to TH5) during the night.

Furthermore, if the usage amount history learning unit 32 determines that the amount of hot water is equal to or greater than a first predetermined usage amount (e.g., 200 L), the nighttime boiling amount calculation means 33 sets the boiling end TH level to level 1, and if the usage amount history learning unit 32 determines that the amount of hot water is equal to or greater than a second predetermined usage amount (e.g., 100 L) and less than the first predetermined usage amount, the boiling end TH level is set to level 2. In the case of level 2, the hot water storage temperature sensor 15 that terminates boiling operation when it detects a predetermined high temperature is selected from the hot water storage temperature sensors 15 installed above and below the hot water storage tank 7 and is set to boil 2/7 of the target boiling amount (up to TH6) during the night, as shown in the distribution of boiling amounts in Figure 2.

Furthermore, if the usage amount history learning unit 32 determines that the amount of hot water or water used is less than a second predetermined usage amount (e.g., 100 L), the end-of-boiling TH level is set to Level 3. At Level 3, as shown in the distribution of boiling amounts in Figure 2, a hot water storage temperature sensor 15 that terminates boiling operation when it detects a predetermined high temperature is selected and set from the hot water storage temperature sensors 15 installed above and below the hot water storage tank 7, in order to boil 1/7 of the target boiling amount (up to TH7) during the night.

The demand determination means 34 determines whether the nighttime boiling amount needs to be increased before the start of the daytime period, and based on the determination result, the control device 29 decides whether or not to perform nighttime boiling operation.

The demand determination means 34 determines whether or not to perform nighttime heating operation based on whether the demand for hot water is low or high. Specifically, if the periodically detected outside air temperature (hereinafter simply referred to as outside air temperature) is below a predetermined outside air temperature, it is determined that the demand for hot water is high, and if the outside air temperature is above the predetermined outside air temperature, it is determined that the demand for hot water is low (here, the predetermined outside air temperature is 20 degrees).

Figure 3 is a flowchart that explains in detail the processing executed by the nighttime boiling amount calculation means 33 and the demand determination means 34.

This process is executed repeatedly every day, for example, at the start of the late-night period while the water heater 1 is running.

When the late-night period begins, first in step S1, the control device 29 checks the amount of hot water used by the user during the specified period and the user's use of filling or reheating the water, based on the learning content learned by the usage history learning unit 32. If there is a history of filling or reheating the water, the determination in step S1 is satisfied (S1 is Yes), and the process proceeds to step S2.

In step S2, the nighttime boiling amount calculation means 33 sets the boiling end TH level to level 1, which is the nighttime boiling amount to be boiled. Then, the process proceeds to step S9, which will be described later.

On the other hand, if there has been no record of filling or reheating the water in step S1, the condition of step S1 is not satisfied (S1 is No), and the process proceeds to step S3.

In step S3, the control device 29 determines whether the amount of water used by the user during the specific period (3:00 AM to 3:00 PM) was equal to or greater than a first predetermined amount of water usage (200 L) based on the learning content learned by the usage amount history learning unit 32. If the amount of water used was equal to or greater than the first predetermined amount of water usage (200 L), the determination in step S3 is satisfied (Yes in S3), the process proceeds to step S2, and the nighttime boiling amount calculation means 33 sets the end-of-boiling TH level to level 1. The process then proceeds to step S11, which will be described later.

On the other hand, if the usage amount is less than the first predetermined usage amount (200 L) in step S3, the condition of step S3 is not met (S3 is No), and the process proceeds to step S4.

In step S4, the control device 29 determines whether the amount of water used by the user during the specified period was equal to or greater than a second predetermined amount of water usage (100 L) based on the learning content learned by the usage amount history learning unit 32. If the amount of water used was equal to or greater than the second predetermined amount of water usage (100 L), the determination in step S4 is satisfied (Yes in S4), and the process proceeds to step S5.

In step S5, the nighttime boiling amount calculation means 33 sets the end-of-boiling TH level to level 2. Then, the process proceeds to step S11, which will be described later.

On the other hand, if the usage amount is less than the second predetermined usage amount (100 L) in step S4, the condition of step S4 is not met (S4 is No), and the process proceeds to step S6.

In step S6, the nighttime boiling amount calculation means 33 sets the end-of-boiling TH level to level 3.

In this way, the nighttime boiling amount calculation means 33 adjusts the amount of hot water and cold water based on the user's past usage over a specific period learned by the usage amount history learning unit 32, and the final boiling TH level (levels 1 to 3) according to the user's usage history for filling or reheating the water. This allows the nighttime boiling amount for nighttime boiling operation using commercial electricity to be adjusted appropriately, and ensures that there is time for daytime boiling operation when private solar power generation can be expected. This prevents hot water shortages, increases the daytime boiling operation rate, and reduces electricity costs.

Next, when the end-of-boiling TH level is set to level 3 in step S6, the demand determination means 34 determines whether the demand for hot water is high or low (S7).

Here, the demand determination means 34 determines whether the outside air temperature detected by the outside air temperature sensor 28 is above a predetermined outside air temperature (here, above 20°C) (S7), and if the outside air temperature is above the predetermined outside air temperature, the demand determination means 34 determines that the demand for hot water is low (S8).

If the demand determination means 34 determines that the demand for hot water is low, the control device 29 sets the water heater not to operate at night (S9).

Furthermore, if the outside air temperature is below a predetermined outside air temperature, the demand determination means 34 determines that this is a period of high demand for hot water (S10). Next, based on the detection value of the hot water storage temperature sensor 15, it is confirmed whether the required amount of hot water for each end-of-boiling TH level (levels 1 to 3) set by the nighttime boiling amount calculation means 33 has been secured (S11). If the required amount of hot water for each end-of-boiling TH level (levels 1 to 3) has been secured (No in S11), the control device 29 sets the nighttime boiling operation not to be performed (S9).

If the required amount of hot water for each set end-of-boiling TH level (levels 1 to 3) has not been secured (S11: Yes), a setting is made to perform nighttime boiling operation (S12), and the nighttime boiling amount calculation means 33 calculates the nighttime boiling amount so that the amount of hot water stored in the hot water storage tank 7 before the start of the daytime period is equal to or greater than the amount of hot water based on the user's past usage history during a specific period learned by the usage history learning unit 32. The control device 29 calculates the nighttime boiling operation time required to boil the nighttime boiling amount before the start of the daytime period, and calculates the start time of the nighttime boiling operation by counting back the nighttime boiling operation time from the end of the nighttime period (S12).

In this way, the demand determination means 34 determines that nighttime heating operation will not be performed when the amount of hot water used during a specific period is low at the end-of-heating TH level 3 and demand for hot water is low. Therefore, the target boiling amount is fully heated during daytime heating operation using privately generated electricity from the solar power generation system 3, and the daytime heating operation rate can be improved on sunny days.

Next, the control of the boiling operation will be described in detail with reference to the flowchart of FIG.
First, based on steps S9 and S12, it is determined whether or not the heating operation can be performed at night (S14).

If nighttime heating operation is required (Yes in S14), when the start time for nighttime heating operation calculated in S13 arrives (Yes in S15), the control device 29 will use commercial power to perform heating operation on some of the hot water that needs to be heated, based on the set end-of-heating TH level (Levels 1 to 3) (S16). Then, when the detection value of the hot water storage temperature sensor 15 reaches the set end-of-heating TH level (Levels 1 to 3) (Yes in S17), the nighttime heating operation will end (S18).

Also, if nighttime heating operation is not required in S14 (S14 is No), S15 to S18 are skipped and the process proceeds to S19.

Then, when the start time of the daytime period (7:00 in this case) arrives (S19 returns Yes), the control device 29 calculates the heating operation time required to heat the amount of hot water used by the user in one day, as learned by the usage amount history learning unit 32 (S20). At this time, if nighttime heating operation is being performed, the control device 29 calculates the daytime heating operation time based on the amount of water required to heat the amount of hot water used in one day, minus the amount of water heated at night.

Then, the control device 29 determines the start time of the daytime heating operation by counting back the calculated required heating operation time from the end time of the heating operation (here, 5:00 PM) (S21).

When the start time of the water heating operation determined in S22 is reached (Yes in S22), the control device 29 performs the daytime water heating operation (S23), and when the amount of hot water reaches the required amount of hot water used (Yes in S24), the control device 29 ends the daytime water heating operation (S25).

In this way, when the demand determination means 34 determines that the demand for hot water is low, the control device 29 reduces the amount of water boiled at night and increases the amount of water boiled during the day when water boiling operation is possible using the privately generated electricity obtained by the solar power generation system 3, thereby reducing the risk of running out of hot water while improving the daytime water boiling operation rate.

Although embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are within the scope and spirit of the invention, as well as the inventions and their equivalents as set forth in the claims.

For example, even if the demand determination means 34 determines that heating operation should not be performed at night, if the amount of hot water stored in the hot water storage tank 7 is significantly low, the control device 29 may determine that the amount of hot water stored has fallen below the minimum amount and perform heating operation, thereby preventing a hot water shortage.

The conditions for the nighttime boiling amount calculation means of the demand determination means 34 determine whether the demand for hot water is high or low. In this embodiment, this determination is made by comparing the outside air temperature with a predetermined outside air temperature, but this is not limited to this. For example, the water supply temperature detected by a water supply temperature sensor (not shown) can be compared with a predetermined water supply temperature (here, the predetermined water supply temperature is 24°C), or, in the case of a hot water storage type hot water heater 1 equipped with a calendar function, it can be determined whether the current season is summer, mid-season, or winter, or whether the amount of hot water used in the evening (3:00 PM to 11:00 PM) is high or low.

In addition, in this embodiment, the daytime heating operation time is set back from the end time of the daytime period by the heating operation time, but heating operation may also start from the start time of the daytime period, or the user may set any time using the remote control 30.

1. Storage-type hot water supply system (hot water supply system)
3 Photovoltaic power generation system 7 Hot water storage tank 16 Heat pump unit 24 Circulation circuit 29 Control device 30 Remote control 31 Target boiling amount calculation means 32 Usage amount record learning unit 33 Nighttime boiling amount calculation means 34 Demand determination means

Claims (3)

A hot water storage tank for storing hot water;
a heating means capable of heating the hot water using privately generated electricity obtained from a solar power generation system;
a control device that controls a boiling operation in which the heating means heats the hot water in the hot water storage tank;
a target boiling amount calculation means for calculating a target boiling amount to be boiled by the end of the daytime period of the next day based on the amount of hot water stored for the next day;
a nighttime boiling amount calculation means for calculating a nighttime boiling amount that boils a portion of the target boiling amount before the start time of the daytime period so that the amount of hot water stored in the hot water storage tank before the start time of the daytime period is equal to or greater than the amount of hot water used based on past usage records during a specific period from before the start time of the daytime period to before the end time of the daytime period,
The control device is provided with a demand determination means for determining whether or not the nighttime boiling amount needs to be boiled before the start time of the daytime period,
A hot water storage type hot water supply device characterized in that, when the demand determination means determines that there is no need to heat water, the control device does not perform heating operation before the start time of the daytime period regardless of the set nighttime heating amount. the control device is capable of acquiring a detection value of an outside air temperature sensor that detects an outside air temperature;
When the outside air temperature is equal to or higher than a predetermined outside air temperature and the amount of hot water based on past usage in the specific period is equal to or lower than a predetermined amount, the demand determination means determines that there is no need to heat the water;
2. The hot water storage type hot water supply device according to claim 1, wherein the control device is configured not to perform the heating operation before the start time of the daytime period. the control device is capable of acquiring a detection value of a feed water temperature sensor that detects a feed water temperature,
When the supply water temperature is equal to or higher than a predetermined water temperature and the amount of hot water based on past usage in the specific period is equal to or lower than a predetermined amount, the demand determination means determines that there is no need to boil the water;
2. The hot water storage type hot water supply device according to claim 1, wherein the control device is configured not to perform the heating operation before the start time of the daytime period.