JP2020034190A - Hot water storage and supply device - Google Patents

Abstract

To provide a hot water storage and supply device capable of shortening a time required for heating sterilization treatment for hot water in a hot water storage tank where Legionella bacteria proliferate, to reduce energy consumption.SOLUTION: A hot water storage and supply device (1), when hot water in a hot water storage tank (5) stays for a certain time or more, is heated by an auxiliary heat source device (4) through a circulation heating circuit (20) to perform a sterilization operation. In the hot water storage and supply device, the hot water storage tank (5) is provided with a plurality of temperature sensors (5b, 5c, 5d) for detecting an internal hot water temperature. In the sterilization operation, circulating means is controlled to adjust an initial circulating flow rate at the beginning of the operation in accordance with the hot water temperature situation inside the hot water storage tank (5) detected by the temperature sensors (5b, 5c, 5d).SELECTED DRAWING: Figure 3

Description

  TECHNICAL FIELD The present invention relates to a hot water storage / hot water supply apparatus that reduces the time required for heat sterilization of hot water in a hot water storage tank in which Legionella bacteria and the like have propagated, thereby reducing energy consumption.

  2. Description of the Related Art Conventionally, hot water storage water heaters with high energy efficiency that can store hot water heated by an external heat source device such as a heat pump water heater or a fuel cell in a hot water storage tank and supply the stored hot water to a hot water supply destination have been widely used. ing. Such a hot water storage / hot water supply device includes an external heat source device, a hot water storage tank for storing hot water heated by the external heat source device, a hot water circulation circuit for circulating hot water between the external heat source device and the hot water storage tank, and the like. The hot water in the tank is circulated through a hot water circulation circuit and heated by an external heat source device, and the heated hot water is returned to a hot water storage tank and stored therein, and supplied to a desired hot water supply destination such as a hot water tap or a bathtub.

  In the above hot water storage / hot water supply device, when the hot water in the hot water storage tank is not used for a long time, the hot water in the hot water storage tank is contaminated with bacteria such as Legionella bacteria and cannot be supplied as it is to the hot water supply or the bathroom. Therefore, in order to kill these germs, a sterilization process of reheating the hot water in the hot water storage tank is performed.

  The sterilization process is performed by repeatedly taking out hot water from the lower part of the hot water storage tank, heating the hot water with the auxiliary heat source device provided in the hot water storage device, and returning the hot water to the upper part of the hot water storage tank. It is reheated to about 75 ° C or higher.

  Usually, the sterilization processing is performed when it is determined that the hot water in the hot water storage tank is not used for a certain time or more (for example, 100 hours or more). However, since the use of hot water in the hot water storage tank is prohibited in principle, the supply path from the hot water storage tank to hot water supply or hot water filling is shut off during sterilization treatment, thereby restricting use for hot water supply or hot water filling.

  Therefore, in order to terminate the sterilization process as soon as possible, it is conceivable to circulate hot water at a large flow rate, heat the hot water with an auxiliary heat source device, and return the hot water from the upper portion in the hot water storage tank. However, when the heated hot water is injected at a large flow rate from the upper portion of the hot water storage tank, there is a problem that the hot water in the hot water storage tank is agitated and the temperature stratification formed in the hot water storage tank collapses. When the temperature stratification formed in the hot water storage tank collapses, a part of the hot water in the hot water storage tank has a low temperature part, and it takes a considerable time to sterilize the hot water in the hot water storage tank to 70 ° C. or more. I was

  On the other hand, in order to perform the sterilization process while maintaining the temperature stratification of the hot water in the hot water storage tank, circulation with a small circulation flow rate may be considered. However, even with a small circulation flow rate, it takes time to reheat the entire hot water in the hot water storage tank, and during that time, the use of hot water in the hot water storage tank for hot water supply and hot water filling is restricted, which is inconvenient for the user. Will be forced.

  The specification of the patent application by the present applicant in Patent Document 1 discloses a hot water storage / hot water supply apparatus that performs a sterilization process while maintaining the temperature stratification of hot water in a hot water storage tank. According to this device, by circulating at a small circulation flow rate immediately after the start of heating for sterilization treatment, and gradually increasing the circulation flow rate after hot water is stored to a certain degree in the hot water storage tank, the inside of the hot water storage tank is gradually increased. The sterilization process can be performed while maintaining the temperature stratification.

Japanese Patent Application No. 2017-059723

  However, in the hot water supply device of Patent Document 1, regardless of the temperature of the hot water in the hot water storage tank, the hot water is circulated with a small circulation flow rate immediately after the start of heating, and the temperature of the hot water in the upper portion of the hot water storage tank is constant. Since the circulating flow rate is gradually increased when is detected, the time required for sterilizing hot water in the hot water storage tank cannot be reduced.

  It is an object of the present invention to provide a hot water storage and hot water supply apparatus in which the time required for heat sterilization treatment of hot water in a hot water storage tank in which Legionella bacteria and the like have propagated is reduced, energy consumption is reduced, and efficiency is improved.

  The hot water supply apparatus according to claim 1 is provided in the heating means for heating the hot water, a circulation heating circuit for taking out the hot water from a lower part of the hot water storage tank, heating the hot water by the heating means and returning the hot water to an upper part of the hot water storage tank, and the circulation heating circuit. And a circulating means, wherein when the hot and cold water in the hot water storage tank stays for a predetermined time or more, the hot water storage device is heated by the heating means through the circulating heating circuit to perform a sterilization operation. A plurality of temperature detecting means for detecting a temperature is provided, and in the sterilization operation, the initial circulation flow rate at the start of the sterilization operation is set according to the temperature of hot water in the hot water storage tank detected by the temperature detection means. It is characterized in that the circulation means is controlled so as to adjust.

  According to a second aspect of the present invention, in the hot water storage device according to the first aspect, the temperature detection unit is a plurality of temperature detection units provided above the hot water storage tank among the plurality of temperature detection units. When the amount of hot water at or above the sterilization temperature at the upper portion is equal to or more than a predetermined amount, the circulating means is controlled so that the initial circulating flow becomes the maximum flow.

  A hot water supply apparatus according to a third aspect is characterized in that, in the invention according to the first or second aspect, the heating means is a combustion type instantaneous hot water supply apparatus.

  According to the invention of claim 1, in the sterilization operation, the circulation unit is controlled so as to adjust the initial circulation flow rate at the start of the sterilization operation according to the temperature of the hot and cold water in the hot water storage tank detected by the temperature detection unit. The initial circulation flow rate is adjusted within a range that does not destroy the temperature stratification of the hot water formed in the hot water storage tank, and the time required for the sterilization operation can be reduced.

  For example, if the temperature of the hot water in the upper part of the hot water storage tank is, for example, less than 65 ° C., the temperature of the hot water of the uppermost layer in the hot water storage tank is low. By doing so, the temperature stratification in the hot water storage tank can be maintained. On the other hand, if the temperature of the hot water in the upper part of the hot water storage tank is, for example, 65 ° C. or higher and the temperature of the hot water in the middle part of the hot water storage tank is, for example, lower than 65 ° C., the hot water of the uppermost layer in the hot water storage tank is compared. Because of the extremely high temperature, the temperature stratification in the hot water storage tank can be maintained even if the liquid is circulated from the beginning at an initial circulation flow rate of, for example, 7 L / min.

  According to the second aspect of the present invention, the predetermined temperature detecting means is constituted by a plurality of temperature detecting means provided at an upper part of the hot water storage tank among the plurality of temperature detecting means, and a sterilizing means at an upper part of the hot water storage tank is provided. When the amount of hot water at or above the temperature is equal to or more than a predetermined amount, the circulating means is controlled so that the initial circulating flow rate becomes the maximum flow rate, so that the same effect as described above can be obtained.

  For example, if the temperature of the hot water in the middle part of the hot water storage tank is, for example, 65 ° C. or higher, the initial circulation flow rate is the maximum flow rate (for example, 8 L / min) because high-temperature hot water is stored near the upper layer in the hot water storage tank. The time required for the sterilization operation can be reduced within a range that does not destroy the temperature stratification in the hot water storage tank even when the hot water is circulated.

  According to the third aspect of the present invention, since the heating means is a combustion type instantaneous hot water supply device, even when the circulation flow rate fluctuates, there is no shortage of hot water heating capacity.

It is a schematic structure figure of a heat pump type hot-water storage hot-water supply device concerning an embodiment of the present invention. It is a detailed block diagram of a hot-water storage hot-water supply apparatus. It is a flowchart of the sterilization operation control of hot water in a hot water storage tank.

  Hereinafter, embodiments for carrying out the present invention will be described based on examples.

The overall configuration of the heat pump hot water storage / hot water supply device 1 will be described.
As shown in FIGS. 1 and 2, a heat pump hot water supply / hot water supply apparatus 1 includes a hot water supply / hot water supply unit 2 having an auxiliary heat source unit 4 and a heat pump heat source unit 3. The hot water supply unit 2 and the heat pump heat source unit 3 are provided with a heating circuit. 10 are connected.

First, the hot water supply unit 2 will be described.
As shown in FIG. 2, the hot water supply unit 2 is connected to an auxiliary heat source unit 4, a hot water storage tank 5 for storing hot water, a hot water passage 6 connected to an upper end of the hot water storage tank 5, and a hot water supply passage 6. A hot water supply passage 7 for supplying hot water to a hot water supply destination, a pouring passage 8 branched from the hot water supply passage 7 to fill the bathtub 15, a bath reheating passage 9 for heating hot water from the bathtub 15, A heating circuit 10 for circulating the hot water in the tank 5 with the heat pump heat source device 3 so as to store the hot water in the hot water storage tank 5; a water supply passage 13 for supplying clean water to the hot water storage tank 5; The control apparatus includes a valve 14, a heat exchanger 12 provided in the bath additional heating passage 9, a control unit 11 for performing various controls, an operation remote controller 41, and the like.

  A plurality of temperature sensors 5a to 5d are provided at appropriate intervals in the vertical direction on the side of the hot water storage tank 5, and detect the temperature of each of the temperature stratified hot water stored in the hot water storage tank 5. In order to prevent the temperature of the stored hot water from dropping, the periphery of the hot water storage tank 5 is covered with a heat insulating material (not shown). Note that the temperature sensors 5a to 5d correspond to "temperature detecting means".

  Next, the heating circuit 10 for connecting the hot water supply unit 2 and the heat pump heat source unit 3 will be described. The heating circuit 10 includes a forward passage 10a, a return passage 10b, and a bypass passage 10c connecting these. The upstream end of the outward passage 10 a is connected to the lower end of the hot water storage tank 5, and the downstream end thereof is connected to the condensation heat exchanger 37 in the heat pump heat source unit 3. The return passage 10 b has an upstream end connected to the condensation heat exchanger 37, and a downstream end connected to the upper end of the hot water storage tank 5.

  A circulation pump 18 is interposed in the middle of the forward passage 10a, and a circulation temperature sensor 10d is provided in a middle of the return passage 10b. A switching three-way valve 19 is interposed at a connection point between the going passage portion 10a and the bypass passage portion 10c. By switching the switching three-way valve 19, the switching between the bypass passage 10c side and the hot water storage tank 5 side can be performed. When the switching three-way valve 19 is switched to the bypass passage portion 10c side, the hot water heated by the heat pump heat source unit 3 is sent back to the heat pump heat source unit 3 without returning to the hot water storage tank 5 so as to be reheated.

  The heat pump heat source unit 3 is controlled by the control unit 11 through the auxiliary control unit 35, and connects the compressor 36, the condensation heat exchanger 37, the expansion valve 38, and the evaporation heat exchanger 39 by the refrigerant pipe 40, thereby forming a heat pump circuit. This is a device for heating hot water using the refrigerant sealed in the refrigerant pipe 40 and the heat of the outside air.

Next, the water supply passage 13 will be described.
The water supply passage 13 supplies low-temperature water from the water supply source to the hot water storage tank 5 and the like. The upstream end is connected to the water supply source, and the downstream end is connected to the lower end of the hot water storage tank 5. A water supply bypass passage 22 branches off from the water supply passage 13 and is connected to the mixing valve 14. A water supply temperature sensor 23 is provided in the water supply passage 13, a water supply opening / closing valve 24 is provided upstream of the branch portion, a check valve 25 is provided downstream of the branch portion, and a reverse check valve 25 is provided in the water supply bypass passage 22. A stop valve 26 is provided. A hot water tap avoidance passage 28 branched from the water supply bypass passage 22 and connected to the hot water supply passage 7 is provided so as to avoid hot water tapping unexpected by the user.

Next, the hot water supply passage 6 and the hot water supply passage 7 will be described.
The hot water supply passage 6 has an upstream end connected to the upper end of the hot water storage tank 5, a downstream end connected to the mixing valve 14, and a hot water supply passage 7 connected to the mixing valve 14. The mixing valve 14 supplies hot water at the hot water set temperature set by the user via the operation remote controller 41 to the hot water supply passage 7 or supplies hot water at the hot water set temperature to the bathtub 15 from the water supply bypass passage 22. The mixing ratio between the low temperature tap water to be supplied and the high temperature tap water supplied from the tap water passage 6 is adjusted. The hot water adjusted to the hot water supply set temperature is supplied from the hot water supply passage 7 to the hot water tap. The hot water supply passage 7 is provided with a hot water supply temperature sensor 30 and a hot water supply flow rate sensor 31 capable of detecting the hot water temperature and the hot water flow rate adjusted by the mixing valve 14, and detects the hot water supply temperature and the hot water supply flow rate.

Next, the pouring passage 8 will be described.
An opening / closing valve 8a is provided in a pouring passage 8 branched from the hot water supply passage 7 to fill the bathtub 15 with water, and a downstream end of the pouring passage 8 is connected to a bath passage passage 9a described later. In order to supply hot water at a set hot water supply temperature to the bathtub 15 via the operation remote controller 41, hot water from the upper portion of the hot water storage tank 5 flows to the mixing valve 14 through the hot water supply passage 6, and the water supply bypass passage 22 in the mixing valve 14. The hot water is mixed with the fresh water from the hot water to form hot water at a hot water supply set temperature, flows into the pouring passage 8, and is supplied to the bathtub 15 through the on-off valve 8 a and the bath additional heating passage 9.

Next, the bath reheating passage 9 and the heat exchanger 12 for reheating the bath will be described.
The heat exchanger 12 heats the hot and cold water in the bathtub 15 by heat exchange between hot and cold water flowing through the additional hot water passage 21 connected to the downstream portion of the auxiliary hot water supply passage 20e and hot and cold water flowing through the additional hot water passage 9. An opening / closing valve 21a is provided in the supplementary hot water passage 21 and is closed so that hot water does not flow into the heat exchanger 12 except during the bath supplementary heating operation.

  The bath reheating passage 9 circulates the hot and cold water in the bathtub 15 and heats the hot water in the heat exchanger 12. The hot water and hot water heated by the heat exchanger 12 is sent to the bathtub 15. It has a bath return passage 9b provided with a reheating pump 16 for sending hot water to the heat exchanger 12. The bath going passage 9a includes a bath going temperature sensor 9c for detecting the temperature of hot and cold water in the bath tub 15 after heat exchange, and the bath returning passage 9b has a reheating pump 16, a bath returning temperature sensor 9d, and a bath tub. A water level sensor 9e for detecting 15 water levels is provided.

  A hot water return passage 21 b to which the downstream end of the additional hot water passage 21 is connected is connected to a downstream portion of the water supply passage 13. An upper auxiliary passage 20a for supplying hot and cold water to the auxiliary heat source unit 4 is branched from the hot water outlet passage 6 and connected to the three-way valve 27, and a lower auxiliary passage 20b for supplying low-temperature hot and cold water to the auxiliary heat source unit 4 Extends from the hot water return passage 21b and is connected to the three-way valve 27, and an auxiliary introduction passage 20c extending from the three-way valve 27 is connected to the auxiliary heat source unit 4.

  A circulation pump 34 is interposed in the auxiliary introduction passage 20c. Auxiliary tapping passage 20e, from which high-temperature hot water heated by auxiliary heat source unit 4 taps, is connected to tapping passage 6 upstream of mixing valve 14, and a circulation temperature sensor 32 and a flow control valve 33 are provided in auxiliary tapping passage 20e. It is interposed. The three-way valve 27 is configured to be able to selectively switch between the hot water storage tank 5 side and the lower auxiliary passage 20b side. Note that the circulation pump 34 corresponds to “circulation means”.

Next, the auxiliary heat source unit 4 will be described.
The auxiliary heat source unit 4 is constituted by a known instantaneous combustion type hot water supply device (gas water heater) having a built-in burner, a heat exchanger, and the like. Can be heated. The hot water heated by the auxiliary heat source unit 4 flows through the auxiliary hot water passage 20e and returns to the hot water storage tank 5 through the hot water passage 6. Note that the auxiliary heat source unit 4 corresponds to a “heating unit”.

The auxiliary heat source unit 4 is used for sterilizing hot water in the hot water storage tank 5.
Specifically, when performing the sterilization operation, the three-way valve 27 is switched to the lower auxiliary passage 20b side, and the circulation pump 34 is operated to supply the low-temperature hot water in the hot water storage tank 5 to the lower auxiliary passage 20b and the auxiliary introduction passage 20c. Then, it is introduced into the auxiliary heat source unit 4. The hot water heated by the auxiliary heat source unit 4 and having a high temperature is returned to the upper part of the hot water storage tank 5 through the auxiliary hot water passage 20e and the hot water passage 6 in order. The circulation heating circuit 20 is formed by a circulation circuit including the lower auxiliary passage 20b, the auxiliary introduction passage 20c, the auxiliary tapping passage 20e, and a part of the tapping passage 6.

Next, the control unit 11 will be described.
The control unit 11 obtains the temperature and flow rate of each part by the temperature sensors 5a to 5d, the circulation temperature sensors 10d and 32, the water supply temperature sensor 23, the hot water supply temperature sensor 30, the other hot water supply flow rate sensors 31, and the like. , The mixing valve 14, the three-way valve 27, the flow control valve 33, other valves, the reheating pump 16, the circulation pumps 18, 34, and the like are operated, and the heat pump heat source unit 3 is operated to heat the hot water at the set hot water supply temperature. Control of hot water storage operation, hot water supply operation, etc. is performed so as to stretch or supply hot water. When it is detected that the hot water in the hot water storage tank 5 has not been used for a long time, the control of the sterilization operation of the hot water in the hot water storage tank 5 described later is performed.

Next, the sterilization operation performed by the heat pump hot water storage / hot water supply device 1 will be described.
In the sterilization operation, if the hot water in the hot water storage tank 5 stays for a certain time (for example, 100 hours) or more, the hot water in the hot water storage tank 5 may be contaminated by propagation of various bacteria such as Legionella bacteria. It is prohibited to use the hot water in the hot water storage tank 5 for hot water supply or hot water filling as it is. Therefore, low-temperature hot water is circulated from the lower portion of the hot water storage tank 5 and is heated by the auxiliary heat source unit 4 through the circulation heating circuit 20 so that the entire hot water in the hot water storage tank 5 is heated to about 70 ° C. or more. Then, various bacteria such as Legionella bacteria are sterilized by heating.

  More specifically, the three-way valve 27 is switched to the lower auxiliary passage 20b side, and the circulation pump 34 is operated so that the hot and cold water in the hot water storage tank 5 is removed from the lower part connected to the lower part of the hot water storage tank 5. The hot water heated by the auxiliary heat source device 4 is introduced into the auxiliary heat source device 4 through the auxiliary passage 20b and the auxiliary introduction passage 20c in order, and the high-temperature hot water heated by the auxiliary heat source device 4 is sequentially passed through the auxiliary hot water supply passage 20e and the hot water discharge passage 6 to the hot water storage tank 5. The hot water in the hot water storage tank 5 is reheated by flowing into the upper part.

  At this time, when the circulation heating circuit 20 is circulated from the beginning at the maximum circulation flow rate, reheating is performed by the auxiliary heat source unit 4 and returned to the upper part in the hot water storage tank 5, the hot water in the hot water storage tank 5 is stirred and the temperature stratification occurs. Then, it takes a long time to reheat the hot and cold water to a temperature of about 70 ° C. or higher in the hot water in the hot water storage tank 5.

  For this reason, the initial circulation flow rate at the start of the sterilization operation is adjusted, for example, within a range of 5 to 8 L / min in accordance with the temperature of the hot and cold water in the hot water storage tank 5 to control the circulation pump 34 to control the circulation heating circuit 20. Is circulated and reheated by the auxiliary heat source unit 4 and returned to the upper portion in the hot water storage tank 5, so that the entire hot and cold water in the hot water storage tank can be quickly removed without breaking the temperature stratification formed in the hot water storage tank 5. It reheats and shortens the time required for sterilization.

  Next, control of the sterilization operation by the heat pump hot water supply / hot water supply device 1 executed by the control unit 11 will be briefly described based on the flowchart of FIG. Note that Si (i = 1, 2,...) In the flowchart represents each step.

  First, when the control unit 11 determines that the hot water in the hot water storage tank 5 has stayed for a predetermined time (for example, 100 hours) or more, a sterilization operation for reheating the hot water in the hot water storage tank 5 to prevent legionella bacteria is performed. Start.

In S1, it is determined whether or not hot water supply or additional cooking operation is performed. If the determination is Yes, the process proceeds to S2, and if the determination is No, the process returns and repeats the determination in S1.
Next, in S2, it is determined that the heating operation is not performed. If the determination is Yes, the process proceeds to S4. If the determination is No, the process proceeds to S3 to simultaneously perform the reheating and the heating operation in the hot water storage tank 5. The control to be performed is executed, and the process returns to S1.

  Here, if the determinations of S1 and S2 are Yes, the hot water supply, the additional heating operation, and the heating operation are stopped, and the hot water in the hot water storage tank 5 remains stagnant. Therefore, the control for adjusting the initial circulation flow rate is performed from S4. You.

  In S4, it is determined whether or not the temperature detected by the first temperature sensor 5d of the hot water storage tank 5 is equal to or lower than 65 ° C. If the determination is Yes, the process proceeds to S5, and the circulation pump is controlled so that the initial circulation flow rate is 5 L / min. 34 is controlled, the circulation heating circuit 20 is circulated, the auxiliary heat source device 4 reheats the temperature to 70 ° C. or higher, and heating for hot water sterilization in the hot water storage tank 5 is performed. Next, the process proceeds to S6, where it is determined whether or not the temperature detected by the first temperature sensor 5d is 66 ° C. or higher and continuous 60 seconds have elapsed. If the determination is Yes, the process proceeds to S14. If the determination is No, S6 is performed. repeat.

  If the determination in S4 is No, the process proceeds to S7, in which it is determined whether the temperature detected by the second temperature sensor 5c of the hot water storage tank 5 is equal to or lower than 65 ° C. If the determination is Yes, the process proceeds to S8, and the initial circulation flow rate is reduced. The circulation pump 34 is controlled so as to be 6 L / min, and heating for hot water sterilization in the hot water storage tank 5 is performed in the same manner as described above. Next, the process proceeds to S9, in which it is determined whether or not the temperature detected by the second temperature sensor 5c is equal to or higher than 66 ° C. and continuous 60 seconds have elapsed. If the determination is Yes, the process proceeds to S14. If the determination is No, S9 is performed. repeat.

  If the determination in S7 is No, the process proceeds to S10, in which it is determined whether the temperature detected by the third temperature sensor 5b of the hot water storage tank 5 is 65 ° C. or less. If the determination is Yes, the process proceeds to S11, where the initial circulation flow rate is reduced. The circulation pump 34 is controlled so as to be 7 L / min, and heating for hot water sterilization in the hot water storage tank 5 is performed in the same manner as described above. Next, the process proceeds to S12, where it is determined whether or not the temperature detected by the third temperature sensor 5b is equal to or higher than 66 ° C. and continuous 60 seconds have elapsed. If the determination is Yes, the process proceeds to S14. If the determination is No, S12 is performed. repeat.

  On the other hand, if the determination in S10 is No, the process proceeds to S13, in which the circulation pump 34 is controlled so that the initial circulation flow rate is 8 L / min, and heating for hot water sterilization in the hot water storage tank 5 is performed in the same manner as described above. Done. That is, when the determination in S10 is No, the detection temperature of the third temperature sensor 5b of the hot water storage tank 5 is equal to or higher than 65 ° C., so that about の of the capacity of the hot water storage tank 5 stores high-temperature water. Therefore, even when circulating at the maximum initial circulation flow rate, the temperature stratification can be maintained without breaking.

  In S14, at least 60 seconds have passed since the start of the initial circulation flow rate of 5 to 7 L / min, and a predetermined amount or more of high-temperature water (high-temperature water having a temperature equal to or higher than the sterilization temperature) is stored in the upper part of the hot-water storage tank 5. Therefore, even if the circulation flow rate is increased, there is no possibility that the temperature stratification will collapse. Therefore, the circulation pump 34 is changed and controlled so as to increase the circulation flow rate 1 L / min, the circulation heating circuit 20 is circulated, and the auxiliary heat source unit 4 reheats. Is returned from the upper portion into the hot water storage tank 5 via the auxiliary hot water passage 20e and the hot water passage 6.

  After performing the process of increasing the circulation flow rate by 1 L / min in S14, the process proceeds to S15, and it is determined whether or not only the sterilization operation is operated alone. If Yes, the process proceeds to S16, and if No, the process proceeds to S1. To return. That is, when the operation other than the sterilizing operation is performed such as hot water supply and additional cooking and the hot water in the hot water storage tank 5 is supplied, the sterilizing operation for Legionella is in a standby state. Instead of continuing the operation, the process returns to S1 to return to the initial state, and the sterilization operation is restarted.

  Next, in S16 to S17, it is determined whether or not the detection temperature of the second temperature sensor 5c of the hot water storage tank 5 is 70 ° C. or higher and continuous 60 seconds have elapsed. If both S16 to S17 are Yes, the process proceeds to S18. It is determined whether or not the circulation flow rate is 8 L / min. If the determination in S18 is No, the process returns to S14, performs the process of increasing the circulation flow rate by 1 L / min, and then repeats the processes of S15 to S18.

  On the other hand, if S16 is No, the process proceeds to S19, and it is determined whether or not the state where the temperature detected by the second temperature sensor 5c is 70 ° C. or less has continuously continued for 15 seconds. Since hot water has not been reheated, the process returns to S1 and returns to the initial state.

  Next, when the determination in S18 is Yes, that is, when it is determined that the circulation flow rate is 8 L / min or more, the process proceeds to S20, and it is determined whether or not the hot water storage tank 5 is full. . If the determination in S20 is Yes, the sterilization operation by reheating the hot water in the hot water storage tank 5 is terminated, and if No, the processes in S15 to S18 are repeated.

The operation and effect of the heat pump water heater will be described.
In the sterilization operation, when the temperature detected by the first temperature sensor 5d (water temperature in the upper part of the hot water storage tank 5) is lower than 65 ° C. at the beginning of the operation, the temperature of the uppermost hot water in the hot water storage tank 5 is low. Therefore, the circulating pump 34 is controlled so as to circulate the initial circulating flow rate at, for example, 5 L / min so as not to break the temperature stratification.

  Further, the detection temperature of the first temperature sensor 5d and the detection temperature of the second temperature sensor 5c (water temperature of the upper part of the hot water storage tank 5) are, for example, 65 ° C. or more, and the detection temperature of the third temperature sensor 5b (the hot water storage tank Is lower than, for example, 65 ° C., since the upper layer of hot water in the hot water storage tank 5 is relatively high temperature, the circulation pump 34 is controlled to circulate the initial circulation flow rate at, for example, 7 L / min. .

  Thus, the circulation pump 34 is controlled so as to adjust the initial circulation flow rate at the beginning of the sterilization operation according to the temperature of the hot and cold water in the hot water storage tank 5 detected by the first to third temperature sensors 5d, 5c, 5b. Since the flow rate is increased stepwise up to the maximum circulation flow rate, the time required for the sterilization operation can be reduced as much as possible while maintaining the temperature stratification of the hot water formed in the hot water storage tank 5 without breaking down.

  Furthermore, when the amount of hot water above the sterilization temperature in the upper part of the hot water storage tank 5 is equal to or more than a predetermined amount, for example, the detection temperature of the third temperature sensor 5b of the hot water storage tank 5 (the temperature of the hot water in the middle part of the hot water storage tank 5) is, for example, If the temperature is 65 ° C. or higher, since the hot water is stored for about の of the capacity of the hot water storage tank 5, the circulation pump 34 should be controlled so that the initial circulation flow becomes the maximum flow (for example, 8 L / min). Thus, the time required for the sterilization operation can be reduced within a range in which the temperature stratification of the hot water formed in the hot water storage tank 5 is not broken.

  That is, at the beginning of the sterilization operation, if the amount of hot water above the sterilization temperature in the upper part of the hot water storage tank 5 is less than a predetermined amount, the hot water taken out from the lower part of the hot water storage tank 5 is circulated at a circulation flow rate of, for example, 5 L / min. Since the circulation pump 34 is controlled to circulate, even if the hot water heated by the auxiliary heat source unit 4 is returned from the upper portion of the hot water storage tank 5, only the hot water of the relatively high temperature layer in the hot water storage tank 5 is injected. The temperature stratification does not collapse without being stirred until the low temperature layer.

  When a certain time has elapsed from the start of the sterilization operation and the temperature detected by the second temperature sensor 5c is, for example, 70 ° C. or higher, the high-temperature layer in the hot water storage tank 5 has expanded to some extent. The circulation pump 34 is changed and controlled so that the circulation flow rate is gradually increased from 5 to 7 L / min (for example, 1 L / min). Therefore, by increasing the circulation flow rate as the high-temperature layer in the hot-water storage tank 5 gradually spreads, the entire hot water in the hot-water storage tank 5 is reheated without disturbing the temperature stratification, and the sterilization operation is performed. It can be completed in a short time.

  In the above embodiment, the case where the temperature of the second second temperature sensor 5c provided in the hot water storage tank 5 is 70 ° C. or more is described as an example, but the invention is not limited to this. For example, the temperature sensor to be detected may be configured to be changeable depending on circumstances such as a case where the diameter of the hot water storage tank is large and a case where the height is large.

  In addition, the above-described embodiment is only an example, and those skilled in the art can implement the present invention in a form in which various changes are added to the above-described embodiment without departing from the spirit of the present invention. Various modifications are also included.

REFERENCE SIGNS LIST 1 heat pump hot water storage / hot water supply apparatus 2 hot water supply / hot water supply unit 3 heat pump heat source unit 4 auxiliary heat source unit 5 hot water storage tanks 5 a to 5 d temperature sensor 10 heating circuit 11 control unit 20 circulation heating circuit 20 a upper auxiliary passage 20 b lower auxiliary passage 20 c auxiliary introduction passage 20 e auxiliary Hot water passage 34 circulation pump

Claims (3)

A hot water storage tank for storing hot water, heating means for heating the hot water, a circulation heating circuit for taking out hot water from the lower part of the hot water storage tank, heating the hot water by the heating means and returning the hot water to the upper part of the hot water storage tank, and provided in the circulation heating circuit In the hot water supply device, comprising: a circulating means, and when the hot water in the hot water storage tank stays for a predetermined time or more, is heated by the heating means through the circulating heating circuit to perform a sterilization operation.
The hot water storage tank is provided with a plurality of temperature detecting means for detecting the temperature of hot water inside the hot water storage tank. In the sterilization operation, sterilization is performed according to the temperature of hot water inside the hot water storage tank detected by the temperature detecting means. A hot water supply apparatus for controlling the circulation means so as to adjust an initial circulation flow rate at the start of operation.   The temperature detecting means is a plurality of temperature detecting means provided in the upper part of the hot water storage tank among the plurality of temperature detecting means, and the amount of hot water having a sterilizing temperature or higher in the upper part of the hot water storage tank is equal to or more than a predetermined amount. The hot water supply apparatus according to claim 1, wherein the circulating unit is controlled so that the initial circulating flow rate becomes a maximum flow rate in the case.   3. The hot water supply apparatus according to claim 1, wherein the heating means is a combustion type instantaneous hot water supply apparatus.