JPH01266464A - Hot water supplying apparatus - Google Patents

Abstract

PURPOSE:To reduce the operating cost of heating by selecting the heating operation either by a heat pump system or by electrical heating using low cost nighttime power upon comparing them to each other within the preset low cost operation zone. CONSTITUTION:A low cost operation zone where the heating by a heat pump system 4 is less expensive than by an electrical heater 10 is determined in advance, and is stored in a memory section 24. Until the hot water temperature becomes the switching temperature, the heating operation by the heat pump system 4 is continued. If the time is within the nighttime supply hours, the heating operation is switched to the heating by the electrical heater 10, which is continued until the set hot water temperature is reached. To heat water in the reservoir tank 1 from the feed water temperature to the set temperature, the heating by the heat pump system is first performed, and, if the time is within the nighttime power supply hours when the hot water temperature rises beyond the low cost operation zone, the heating operation is automatically switched to the heating by the electrical heater 10.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a water heater equipped with a heat pump system and an electric heater as a heating source for hot water in a hot water storage tank.

(Prior art) As a conventional example of the above configuration, for example, Japanese Patent Application Laid-Open No. 59-215
The device described in Japanese Patent No. 534 can be mentioned.

In this device, a heat exchanger that acts as a condenser in a heat pump system is installed at the bottom of a hot water storage tank that has a hot water inlet at the top and a water inlet at the bottom, while an electric Heater is installed. With this configuration, even while the newly supplied water is being boiled to the set water temperature by the heat pump system, the electric heater can locally localize the hot water near the hot water inlet to use a small amount of additional hot water. By heating the water, hot water can be supplied as high-temperature water.

(Problems to be Solved by the Invention) The conventional water heater described above has a configuration in which the hot water in the hot water storage tank is mainly heated by condensed heat in the heat pump system from the water supply temperature to the set hot water temperature. Therefore, when the outside air temperature is low or the set water temperature is high, the heat exchange efficiency with the outside air in the evaporator and the heat exchange efficiency with hot water in the condenser decreases. There is a problem that energy efficiency (hereinafter referred to as EER) cannot be obtained, and as a result, operating costs increase.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide a water heater that can reduce operating costs compared to the conventional water heater without impairing user comfort.

(Means for Solving the Problems) Therefore, as shown in FIG. 1, the water heater according to the first aspect of the present invention includes a heat pump system 4 that can heat hot water in a hot water storage tank 1 to a first set temperature. and an electric heater 10 capable of heating to a temperature higher than the first set temperature, the energy efficiency during heating operation by the heat pump system 4 is determined by the electric heater 10.
storage means 24 for storing a preset low-cost operation region based on the results of comparison with the heating operation according to the present invention; and hot water temperature detection means 11 for detecting the temperature of hot water in the hot water storage tank 1.
and outside air temperature detection means l2 for detecting the outside air temperature state,
It is determined whether or not each detected value by each of the detection means 11 and 12 is within the low-cost operation region, and when it is within the low-cost operation region, the heating operation by the heat pump system 4 is performed, or the low-cost operation region is determined. A heating control means 21 is provided which selects and controls the heating operation of the electric heater 10 when outside, and furthermore, the electric heater 10 is configured as an electric heater exclusively for late-night power supply, and the electric heater 10 is configured to be an electric heater exclusively for late-night power supply. Based on the determination result for the low-cost operation region, <<the operation is controlled by the heating control means 2l in order to switch between the heat pump system 4 and the electric heater 10 and heat up to the set water temperature;
The operation is controlled by the heating control means 21 in order to limit the heating operation of the heat pump system 4 to the low-cost operation region outside of the late-night power supply time period.

The water heater according to the second claim is the water heater according to the first claim, further comprising a designated time storage means 31 for storing the designated boiling time, and a designated time storage means 31 for storing the designated boiling time. An operation period setting means 32 is provided for setting a heating operation period for boiling hot water to a set water temperature, and during the heating operation period, when the set hot water temperature exceeds the upper limit water temperature of the low cost operation region, the operation period setting means 32 is provided. The operation is controlled by the heating control means 21 so that the heat pump system 4 performs a heating operation up to the lower of the set hot water temperature and the first set temperature.

(Function) In the water heater according to the first aspect, when heating the hot water in the hot water storage tank 1 from, for example, the supply water temperature to the set hot water temperature, the heat pump system 4 first starts heating the hot water, When the temperature rises and goes out of the low-cost operation range, heating is automatically switched to electric heater 10. In other words, the heating operation in heat pump system 4 is E
It is controlled to operate in a temperature range where the ER is favorable, that is, a temperature range where the unit energy cost is lower than heating by the electric heater 10. Then, when the water temperature rises or the outside air temperature is low and the heat pump system 4 can no longer maintain a heating operation at a good EER, the heating operation is automatically switched to the electric heater 10. In this way, by operating the heat pump system 4 and the electric heater 10 in a temperature range where the energy unit is low, heating to the set water temperature is controlled. This makes it possible to reduce heating operation costs compared to the case where this was done. Moreover, the electric heater 10 is replaced by an electric heater 1 exclusively for late-night electricity.
0, heating to the set water temperature is performed while performing switching control as described above based on a pre-determined low-cost operating range compared to cheaper late-night electricity costs, further reducing heating operating costs. can do. Then, during periods other than the late-night power supply hours, the heat pump system 4
By performing the heating operation within the above-mentioned low-cost operation range, for example, even when a large amount of hot water in the hot water storage tank l is used and new heating is required from the water supply water temperature state, the heating operation can normally be performed immediately. Sufficient heating operation by the heat pump system 4 for warmth is ensured by the late-night power supply start time, and at this late-night power supply start time, the hot water is heated to the upper limit of the above-mentioned low-cost operation range at a low unit energy price. Therefore, during the time-limited late-night power supply hours mentioned above, heating operation starts from an intermediate hot water temperature, making it possible to more reliably heat the hot water to the set water temperature, improving user comfort. Operating costs can be reduced without any loss.

On the other hand, in the water heater according to the second aspect, a heating operation is performed to boil the hot water in the hot water storage tank l to a set water temperature in accordance with the designated boiling time.

In other words, if the daily usage pattern of hot water is predicted, such as using a large amount of hot water when taking a bath in the evening, by setting the temperature to boil according to the time of use, the heat retention time in the high temperature state can be reduced. is shorter, thus dissipating less heat and reducing energy loss. However, at this time, if the designated boiling time is set outside the late-night power supply time period, the heating operation by the heat pump system 4 limited to the low-cost operation area as described above,
There is a possibility that high temperature hot water that satisfies the user cannot be supplied. Therefore, at this time, the heat pump system 4 is operated beyond the above-mentioned low cost operation range up to the set hot water temperature, or, if this set hot water temperature exceeds the first set temperature of the heating upper limit temperature by the heat pump system 4, to this first set temperature. By performing the heating operation according to the heating operation, it becomes possible to maintain the comfort of use for the user.

(Embodiments) Next, specific embodiments of the water heater of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a schematic diagram showing the overall configuration of a hot water supply system according to an embodiment of the present invention. In the figure, 1 is a closed hot water storage tank, and the upper end of this hot water storage tank 1 is attached to a hot water supply pipe 2. In addition, the lower end portions are connected to the water supply pipe 3, respectively. When the valve (not shown) on the tip side of the hot water supply pipe 2 is opened, the hot water stored in the hot water storage tank 1 is pushed up from the upper side by the pressurizing force of the tap water acting through the water supply pipe 3. The hot water is then supplied to the hot water supply pipe 2.

The hot water storage tank 1 is selected to have an internal capacity that can store approximately the amount of hot water used on -1 day.

At the bottom of the hot water storage tank 1, a hot water heating heat exchanger 5, which is a component of the heat pump system 4, is disposed. The heat pump system 4 further includes a compressor 6,
It has an air heat exchange type evaporator 7 and an expansion mechanism 8, and these devices 6.7.8 and the hot water heating heat exchanger 5 are connected via refrigerant piping 9 to enable refrigerant circulation. By doing so, the heat pump system 4 heats the hot water in the hot water storage tank l with the heat of refrigerant condensation in the hot water heating heat exchanger 5.
It consists of When heating the hot water in the hot water storage tank 1 with this heat pump system 4, for example, 65°
Heating up to C is possible.

Further, an electric heater 10 is further attached to the bottom side of the hot water storage tank 1, and the hot water in the hot water storage tank 1 can also be heated by this electric heater 10. This electric heater 10 is designed exclusively for late-night power, and heating is performed using cheap late-night power only during the limited late-night power supply time period, for example, from 1:00 to 6:00 at night. When the electric heater 10 heats the hot water in the hot water storage tank 1, it can be heated up to a temperature higher than the upper limit heating temperature in the heat pump system 4, for example, 85°C.

A hot water temperature detector (hot water temperature detecting means) 11 composed of a thermistor is attached to a lower position on the side wall surface of the hot water storage tank 1. This hot water temperature detector 11 detects the temperature of the hot water stored in the hot water storage tank 1 at the bottom side, and therefore, if there is a temperature difference between the top side and the bottom side, the temperature on the lower side is detected. be done. On the other hand, in the vicinity of the evaporator 7, an outside air temperature detector (outside air temperature detection means) 12 made of a thermistor for detecting the outside air temperature state is arranged.

The detection signals from each of the detectors 11 and 12 are input to a heating operation control section (heating control means) 21, respectively. This heating operation control section 21 has a function of selecting a more efficient heating operation mode from each input detection signal and issuing a heating command to the heat pump system operation control section 22 and the electric heater operation control section 23. However, the details will be explained later. When a heating command is input to the heat pump system operation control unit 22, the heat pump system operation control unit 22 starts operating the compressor 6 and the fan (not shown) attached to the evaporator 7. Then, the heat pump system 4 performs a heating operation. Further, when a heating command is input to the electric heater operation control section 23, the electric heater operation control section 23 energizes the electric heater 1O, and the electric heater 10 performs a heating operation.

The heating command in the heating operation control section 21 is based on the set water temperature set by the user and the heat pump system 4.
The first set temperature (65°C) and the second set temperature (
85°C) and the detected hot water temperature, and further compares and discriminates the operating conditions stored in advance in the storage unit (storage means) 24. The control performed by the heating operation control section 21 will be explained with reference to the control flowchart in FIG. 3.

In the heating operation control section 21, when the heating operation switch is turned on by the user, first step S is performed.
1, the water temperature detected by the hot water temperature detector 11 and the outside temperature detected by the outside air temperature detector 12 are read. This reading is performed at appropriate sampling intervals, and the read values are successively changed. Next, in step S2, the water temperature is compared with a set water temperature set by the user. If the hot water temperature is higher than the set water temperature, the heating operation is naturally maintained in a stopped state (step S3), and if it is lower than the set hot water temperature, the process moves to step S4, where the heat pump system 4 and the electric heater 10 are connected. A switching temperature, which serves as a criterion for determining whether heating should be performed, is set based on each of the above-mentioned read values.

FIG. 4 shows the energy efficiency (EER) that changes with changes in outside air temperature and hot water temperature when heating is performed using the heat pump system 4.

As shown in the figure, the lower the outside temperature and the higher the hot water temperature, the lower the EER. On the other hand, when heating is performed using the electric heater 10, the EER is approximately constant (approximately 0.86). By adding to the EER of this electric heater 10 the ratio of the unit price of electricity when heating with the heat pump system 4 and the unit price of late-night electricity supplied to the electric heater 10, which one has the lower heating cost It is possible to formulate what will happen, and the branch line is indicated by A in the figure. In other words, when the EER becomes smaller than about 3 due to heating by the heat pump system 4, the heating cost is lower with the electric heater 10, and in the operating range where the EER is maintained at 3 or more, the heating cost is lower than heating with the electric heater 10. Become cheap. In this way, the operating range in which heating by the heat pump system 4 is cheaper than the electric heater 10, that is, the low-cost operating range, is determined in advance, and the boundary condition of this low-cost operating range, that is, the outside air temperature along the branch line A, is determined in advance. The correspondence relationship with the water temperature is stored in the storage section 24. From this correspondence, for example, when the outside temperature is 15°C, the hot water temperature of 40°C on the branch line A is set as the switching temperature.

After setting the switching temperature as described above, the hot water temperature is compared with the switching temperature in step S5 of FIG. The heat pump system 4 heating operation continues.

If the switching hot water temperature is lower than the set hot water temperature, the hot water temperature will reach the switching hot water temperature first by continuing the heating operation, and at this time, the process moves from step s5 to step S7. In this step, it is determined whether or not the boiling time has been designated by the user. Here, the case where no designation has been made will first be described. At this time, in step S8, it is subsequently determined whether or not the time at the time of this step processing is within the late-night power supply time period, and if it is the late-night power supply time period, the heating operation by the electric heater 10 is performed in step s9. can be switched to Next, the processes of steps 5l-S5 and S7 to S9 are repeated,
The heating operation by the electric heater 1o continues until the set water temperature is reached. In this way, when heating the hot water in the hot water storage tank 1 from, for example, the supply water temperature to the set hot water temperature, heating by the heat pump system 4 is first started, and the hot water temperature rises and goes out of the low cost operation range. If it is within the late-night power supply time period, heating by the electric heater 10 is automatically switched. As a result, the heat pump system 4 and the electric heater 10 are each operated in a temperature range where the unit energy cost is low and heat up to the set water temperature. Heating operation costs are reduced compared to

On the other hand, if it is determined in step S8 that it is not within the late-night power supply time period, the operation is stopped in step S3, and as a result, the heat pump system 4 is not operated up to the switching temperature outside the late-night power supply time period. Then, the electric heater 10 heats the water to the set temperature until the midnight power supply time period arrives. As a result, even if, for example, a large amount of hot water in the hot water storage tank 1 is used and it is necessary to heat the water from the supplied water temperature, the heat pump system 4 can reduce the above-mentioned cost at a low energy unit price by the time when power supply starts in the middle of the night. It is possible to heat the hot water to the upper limit of the operating range, and therefore, during the time-limited late-night power supply hours mentioned above, heating operation starts from the intermediate hot water temperature, so in the morning, heating to the set hot water temperature is possible. can be done more reliably,
Operating costs can be reduced without compromising user comfort.

By the way, in general, a large amount of hot water is used when taking a bath in the evening, and a small amount is used intermittently from morning to evening.゛Even under such conditions of use, when boiling in the morning as described above,
The heat retention time in the high temperature state becomes longer, and therefore the amount of heat dissipated increases, resulting in increased energy loss. Therefore, in the above embodiment, the boiling time can be arbitrarily designated by the user's selection. That is, an operation switch for boiling designated time and a time designation switch are provided, and in step s7 in FIG. 3, it is determined whether the time designation switch is turned on. If it is in the ON state, step S10 constituting the designated time storage means 31
At , the content of the operation switch at the designated boiling time, that is, the designated boiling time is read and stored. Next, in step Sll constituting the operation period setting means 32, the heating capacity of the heat pump system 4 is roughly estimated based on the outside temperature, and the time required to boil the water to the set water temperature is calculated. As a result, the operation start time before the designated boiling time is determined, and the period from this start time to the designated boiling time is set as the operating time period.

Subsequently, in steps S12 and S13, it is determined whether the time at the time of processing these steps is within the operating time zone set above or within the late night power supply time zone. If it is outside the operating hours,
The process of returning to S1 via steps S12 to S33 is repeated, and after the hot water temperature reaches the upper limit temperature of the low-cost operation region, the stopped state of the heating operation is maintained. In addition, if it is within the operating hours and also within the late-night power supply time period, the heat pump system 4 will operate in the low-cost operation range even outside the late-night power supply time period, as in the case without time specification. The hot water is heated to the upper limit temperature at , and heated to the set temperature using the electric heater 10 during the late night power supply time period.

On the other hand, if the operating hours do not include the late-night power supply hours, the process moves from step S13 to S14, and in step S14, the detected hot water temperature is set to the first When compared with the set temperature, if the temperature is lower than the first set temperature, a heating command is output by the heat pump system 4 in step S6, and the process returns to step Sl. In other words,
If a time is specified and the operating time is outside the late-night power supply time, heating will not be performed by the electric heater 10 and only heating will be performed by the heat pump system 4, but in this case as well, the above-mentioned low-cost operation area is applied. If the operation is kept at the upper limit temperature, there is a risk that the hot water desired by the user may not be supplied during the designated boiling time. Therefore, by making it possible to heat the heat pump system 4 to the upper heating temperature limit beyond the above-mentioned low-cost operation range,
Heating is performed up to the set temperature, or if the set temperature is set above the heating upper limit temperature, up to this heating upper limit temperature.

If the designated boiling time is set outside the midnight power supply time period as in 2, the heating operation by the heat pump system 4 is performed beyond the above-mentioned low-cost operation range, so that the boiling designated time is set outside the midnight power supply time zone. This makes it possible to supply hot water that is heated to a higher temperature at the same time.
It becomes possible to supply hot water without impairing the user's comfort.

In the above embodiment, an example is shown in which an outside air temperature detector 12 that directly detects outside air temperature is provided, but other state quantities that are correlated with changes in outside air temperature, such as the temperature of water supplied to the hot water storage tank 1, etc. It is also possible to adopt a configuration that detects.

(Effects of the Invention) As described above, in the water heater according to the first claim of the present invention, the heat pump system performs heating operation within a preset low-cost operation range, and when the water heater operates outside the low-cost operation range. Since heating operation using the electric heater is automatically selected, heating is performed using a combination of heating operations each having a low energy unit cost, and as a result, heating operation costs can be reduced compared to the conventional method. Moreover, compared to heating with an electric heater that uses cheap late-night electricity, heating operation is performed while performing switching control as described above based on a pre-determined low-cost operation range, which further reduces heating operation costs. can be reduced.

In addition, the heat pump system will heat the hot water to the upper limit of the low-cost operation range at a low energy unit price by the time the late-night power supply starts, and during the time-limited late-night power supply period, the heating operation will start from the intermediate hot water temperature. Therefore, the hot water can be heated to the set temperature more reliably, and operating costs can be reduced without compromising user comfort.

Furthermore, in the water heater according to the second claim, when the designated boiling time is set outside the late night power supply time zone,
The heating operation by the heat pump system is performed beyond the above-mentioned low cost operation range up to the set hot water temperature, or if this set hot water temperature exceeds the first set temperature of the heating upper limit temperature by the heat pump system, to this first set temperature. Therefore, it is possible to supply hot water at a higher temperature, thereby making it possible to supply hot water without impairing the user's comfort.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram of a water heater according to the present invention, FIG. 2 is a schematic diagram showing the overall configuration of a water heater according to an embodiment of the invention, FIG. 3 is a flowchart of heating operation control of the water heater, and FIG. FIG. 4 is a graph for explaining the low-cost operation region of the heat pump system in the water heater. 1... Hot water storage tank, 4... Heat pump system,
10... Electric heater, 11... Hot water temperature detector (hot water temperature detection means), 12... Outside air temperature detector (outside air temperature detection means), 21... Heating operation control section (heating control means) ,2
4...Storage unit (storage means), 31...Specified time storage means, 32...Operation period setting means. Patent applicant: Tokyo Electric Power Company, Inc. Patent applicant: Daikin Industries, Ltd. &jiC)

Claims (1)

[Claims] 1. A heat pump system (4) capable of heating hot water in a hot water storage tank (1) to a first set temperature, and an electric heater (10) capable of heating hot water to a temperature higher than the first set temperature. A water heater comprising: storing a preset low-cost operation region based on the result of comparing the energy efficiency during heating operation by the heat pump system (4) with that during heating operation by the electric heater (10); storage means (2)
4), hot water temperature detection means (11) for detecting the temperature of hot water in the hot water storage tank (1), outside air temperature detection means (12) for detecting the outside temperature state, and each of the above-mentioned detection means (11) (
It is determined whether or not each detected value in step 12) is within the low-cost operation region, and if it is within the low-cost operation region, heating operation by the heat pump system (4) is performed, and if it is outside the low-cost operation region. Sometimes the above electric heater (10
heating control means (21) for controlling the operation by selecting heating operation by each of the electric heaters (
10) is configured with an electric heater exclusively for late-night electricity, and
During the late-night power supply period, the heating control means (21) switches between the heat pump system (4) and the electric heater (10) based on the determination result for the low-cost operation area, and heats the water to the set water temperature. While controlling the operation, the heating control means (
21) A water heater characterized in that its operation is controlled by. 2. Specified time storage means (31
) and the hot water storage tank (1) according to the specified boiling time above.
An operation period setting means (32) is provided for setting a heating operation period for boiling the hot water in the tank to a set hot water temperature, and during the heating operation period, the set hot water temperature is higher than the upper limit hot water temperature of the low cost operation range. If the temperature exceeds the above, the heat pump system (4
) to perform heating operation according to the heating control means (21).
2. The hot water supply device according to claim 1, wherein the operation is controlled by the following.