JP2011012886A - Hot water supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot water supply system which suppresses waste energy consumption due to unnecessary sterilization treatment of hot water in a hot water storage tank.SOLUTION: The hot water supply system includes: a hot-water-delivery-time calculating means 52 calculating a unit layer volume hot water delivery time which is time for supplying a unit layer volume Vb of hot water from the hot water storage tank 31 to a hot water delivery pipe 2; and a tank-interior-retention-time calculating means 54 which controls tank interior retention time for each layer of three hot water layers L1-L3 having the unit layer volume Vb and vertically stacked, and calculates the tank interior retention time by performing tank interior retention time updating processing for setting, in the hot water layer L1 of the uppermost layer and the hot water layer L2 of the intermediate layer, time obtained by adding the unit layer volume hot water delivery time to previous tank interior retention time of the hot water layer one layer below as the tank interior retention time of the layers L1, L2 and setting, in the hot water layer L3 of the lowest layer, the unit layer volume hot water delivery time as the tank interior retention time, each time the unit layer volume hot water delivery time is calculated by the hot water delivery time calculating means 52.

Description

  The present invention relates to a hot water supply system including a hot water storage tank unit.

  Conventionally, a hot water supply system is known in which an instantaneous heating type gas water heater is connected in series downstream of a hot water storage tank unit that heats hot water in a hot water storage tank by a heat pump (see, for example, Patent Document 1).

  In this way, when hot water is supplied using hot water stored in the hot water storage tank, various bacteria such as Legionella bacteria propagate in the hot water in the hot water storage tank when the temperature of the hot water in the hot water storage tank continues to decrease. It will be easy to do. Therefore, a hot water supply system has been proposed in which hot water in a hot water storage tank is boiled to a high temperature in the midnight hours to sterilize the hot water and prevent unsanitary hot water containing various bacteria from being supplied (for example, Patent Document 2). reference).

  In the hot water supply system described in Patent Document 2, when the amount of remaining hot water in the hot water storage tank becomes a predetermined amount or less, the hot water in the hot water storage tank is kept at 40 ° C. in the daytime period (7:00 am to 11:00 pm). It is heated up to 60 ° C. in the night time zone (from 11:00 to 7:00 in the morning). As a result, during the daytime hours when the amount of hot water used is large, the temperature of the hot water sent from the hot water storage tank to the heat pump at the time of boiling is lowered to prevent a reduction in the heating efficiency of the hot water in the heat pump.

JP 2000-329401 A Japanese Patent Laid-Open No. 2003-130452

  In the hot water supply system described in Patent Document 2, the hot water in the hot water storage tank is unconditionally boiled up to 60 ° C. in the night time zone. However, when the capacity of the hot water storage tank is small or when the amount of hot water used is large, the time for hot water to remain in the hot water storage tank is shortened. If the hot water stays in the hot water storage tank does not exceed the residence time in which miscellaneous bacteria can easily propagate, it is not necessary to heat the hot water in the hot water storage tank to 60 ° C. for sterilization. Therefore, when the hot water in the hot water storage tank is boiled up to 60 ° C unconditionally, even if the hot water stays in the hot water storage tank for a short time and sterilization is unnecessary, the heating efficiency of the hot water in the heat pump is low. There is an inconvenience that wasteful energy is consumed due to boiling.

  Then, an object of this invention is to provide the hot water supply system which suppressed the unnecessary sterilization process of the hot water in a hot water storage tank, and wasted energy consumption.

  The present invention has been made to achieve the above object, and is connected to a hot water storage tank, a hot water supply pipe connected to the upper part of the hot water storage tank and supplied with hot water from the hot water storage tank, and a lower part of the hot water storage tank. A water supply pipe for supplying water to the hot water storage tank, a heating unit for heating the hot water in the hot water storage tank, a flow rate of water supplied from the water supply pipe to the hot water storage tank, or the hot water supply pipe from the hot water storage tank A hot water storage tank flow rate sensor for detecting a flow rate of hot water supplied to the hot water tank.

Then, based on the detected flow rate of the hot water storage tank flow sensor, the amount of water supplied from the water supply pipe to the hot water storage tank or the amount of hot water supplied from the hot water storage tank to the hot water discharge pipe is integrated, and the hot water storage tank A hot water time calculating means for measuring a hot water time of a unit layer capacity, which is a time required when hot water for a unit layer capacity obtained by dividing the capacity of the hot water by a predetermined number is supplied from the hot water storage tank to the hot water discharge pipe; An elapsed hot water calculation time for measuring an elapsed time from the time when the unit layer capacity hot water time is calculated at a predetermined time by the calculation means until the time when the unit layer capacity hot water time is calculated by the hot water time calculation means; The predetermined number of tanks having a unit layer capacity stacked vertically in the hot water storage tank, wherein the hot water in the hot water storage tank stays in the hot water storage tank. For each hot water layer other than the lowermost layer, the calculated unit layer hot water time of the lower hot water layer is managed for each hot water layer and each time the unit layer capacity hot water time is calculated by the hot water time calculating means. The time obtained by adding the calculated unit layer hot water time to the residence time in the tank at the time when the time measurement is started is used as the own tank residence time, and for the lowermost hot water layer, the calculated unit layer The tank residence time update process is performed with the tapping time as its own residence time, and the unit layer tapping time is calculated by the tapping time calculation means until the unit layer tapping time is calculated. The residence time calculation in the tank for calculating the residence time in the tank of the uppermost hot water layer is added to the residence time in the tank of the uppermost hot water layer, which is calculated by the elapsed time calculation means. means When the residence time in the tank of the uppermost hot water layer is equal to or longer than the sterilization necessity determination time set on the assumption that germs propagate in the hot water in the hot water tank, the heating means stores the hot water storage. According to the present invention, the water supply pipe is connected to the lower part of the hot water storage tank, and further comprises a sterilization processing means for performing a sterilization process for heating the hot water in the tank to a predetermined sterilization temperature or higher. Since the hot water pipe is connected to the upper part of the hot water storage tank, water is supplied from the lower part in the hot water storage tank as hot water staying in the upper part is supplied to the hot water pipe. For this reason, the hot water in the hot water storage tank stays in the hot water storage tank as it goes from the bottom to the top.

  Then, the hot water in the hot water storage tank is divided into a predetermined number of hot water layers and managed by the tank residence time calculating means, and the hot water is discharged from the hot water storage tank next by calculating the stay time in the tank of each hot water layer. It is possible to easily calculate the time that the hot water in the upper part of the hot water storage tank stays in the hot water storage tank.

  And when the residence time in the tank of the uppermost hot water layer in the hot water storage tank becomes equal to or longer than the sterilization determination time by the sterilization processing means, the sterilization processing is performed at an unnecessary timing by performing the sterilization processing. Can be avoided, and wasteful energy consumption can be suppressed.

  The heating unit is connected to the heating return pipe connected to the lower part of the hot water storage tank, the heating forward pipe connected to the upper part of the hot water storage tank, the heating return pipe and the heating forward pipe, and the heating unit Heating means for heating hot water in the hot water storage tank supplied via a return pipe and returning the hot water to the hot water storage tank via the heating forward pipe; After the residence time update process is performed and until the next hot water discharge time is calculated by the hot water calculation means, the residence time in the tank of each hot water layer set by the tank residence time update process is set. A hot water storage temperature sensor for adding the elapsed time calculated by the elapsed time of the hot water to calculate a residence time in the tank of each hot water layer and detecting a temperature of the hot water in the hot water storage tank; and the hot water storage temperature sensor of Hot water storage temperature control means for performing hot water storage tank temperature adjustment processing for heating hot water in the hot water storage tank to the predetermined temperature by the heating means when the outlet temperature becomes lower than a predetermined temperature lower than the sterilization temperature, and the heating A heating flow rate sensor for detecting the flow rate of hot water flowing through the return pipe and the heating forward pipe, and hot water returning from the hot water storage tank to the hot water storage tank via the heating unit based on the detected flow rate by the heating flow rate sensor Each time the accumulated amount of hot water returning from the hot water storage tank to the hot water storage tank via the heating unit increases by the unit layer capacity, each hot water layer calculated by the residence time calculating means in the tank For the remaining time in the tank, the residence time in the tank of the uppermost hot water layer is the residence time in the tank of the lowermost hot water layer, and for each hot water layer other than the uppermost layer, Characterized by comprising a tank residence time correction means for performing tank residence time correction processing of the tank residence time of the hot water layer on one its own tank residence time.

  According to the present invention, while the hot water storage tank temperature adjustment process is performed by the hot water storage temperature control means, the hot water of the lowermost hot water layer in the hot water storage tank is transferred to the uppermost layer via the heating unit. Supplied to the hot water layer. As a result, the hot water of the lowermost hot water layer that has been the shortest residence time in the tank until then is supplied to the uppermost hot water layer, and the residence time of each hot water layer in the tank increases from top to bottom. Will be changed sequentially.

  Therefore, the hot water storage tank temperature adjustment process is performed by performing the in-tank residence time correction process in which the in-tank residence time of each hot water layer is sequentially shifted from top to bottom by the in-tank residence time correction means. Even in such a case, the residence time in the tank of each hot water layer can be managed with high accuracy.

  A water supply branch pipe connecting the water supply pipe and the hot water supply pipe; a water amount variable valve provided in the water supply branch pipe for changing an opening degree of the water supply branch pipe; and the hot water storage tank of the hot water supply pipe A hot water variable valve that is provided between the connecting portion and the connecting portion of the water supply pipe and changes the opening of the hot water supply pipe, and is located in the middle of the outlet pipe at the downstream side of the connecting portion between the hot water pipe and the water supply pipe. A hot water heater that heats hot water flowing through the hot water pipe, and the sterilization means closes the hot water variable valve and opens the water variable valve during the sterilization process. It is characterized by doing.

  According to the present invention, while the sterilization process is being performed by the sterilization means in a state where the hot water from the hot water storage tank to the hot water discharge pipe is prohibited by closing the hot water variable valve, the hot water amount is variable. By closing the valve and opening the water amount variable valve, the water supplied from the water supply pipe can be heated by the water heater and supplied to the tapping pipe. Therefore, hot water supply from the hot water discharge pipe can be maintained even during the sterilization process.

The block diagram of the hot-water supply system of this invention. The block diagram of a tank controller. Explanatory drawing which showed the condition when supplying hot water to a tapping pipe from a hot water storage tank, and the situation when heating the hot water in a hot water storage tank. Explanatory drawing of the residence time update process in a tank. Explanatory drawing of the residence time correction process in a tank. The operation | movement flowchart of a tank unit. The operation | movement flowchart of the tank unit following FIG. The flowchart of ON / OFF setting of a refresh flag. The flowchart of ON / OFF setting of a high temperature hot water storage flag.

  Embodiments of the present invention will be described with reference to FIGS. Referring to FIG. 1, the hot water supply system of the present embodiment is configured by instantaneous heating type water heater 10, tank unit 30, and heat pump unit 60 (corresponding to the heating unit of the present invention).

  The heat pump unit 60 includes a heat pump 70 (corresponding to the heating means of the present invention) configured by connecting a compressor 71, a condenser 72, a decompressor 73, and an evaporator 74 through a refrigerant circulation path 75. . The condenser 72 is connected to a heating forward pipe 64 connected to the upper part of the hot water storage tank 31 and a heating return pipe 67 connected to the lower part of the hot water storage tank 31, and the refrigerant in the refrigerant circulation path 75, the heating forward pipe 64 and the heating are connected. The hot water in the hot water storage tank 31 is heated by exchanging heat with the hot water in the return pipe 67.

  The heating return pipe 67 has a circulation pump 65 for circulating hot water stored in the hot water storage tank 31 via the condenser 72, and a return for detecting the temperature of the hot water supplied from the hot water storage tank 31 to the condenser 72. A thermistor 41 and a heating flow rate sensor 45 that detects the flow rate of hot water flowing through the heating return pipe 67 are provided. The heating forward pipe 64 is provided with an outward thermistor 66 that detects the temperature of hot water supplied from the condenser 72 to the hot water storage tank 31.

  Then, the operations of the heat pump 70 and the circulation pump 65 are controlled by a control signal output from the heat pump controller 80 which is an electronic unit constituted by a microcomputer or the like so that the temperature detection signal from the forward thermistor 66 becomes a predetermined value. The

  The heat pump controller 80 is communicably connected to the tank controller 50, and when receiving a heating instruction signal from the tank controller 50, based on the detected temperature of the return thermistor 41 and the detected temperature of the forward thermistor 66, The heat pump 70 is operated to maintain the hot water in the hot water storage tank 31 near the set temperature (45 ° C. or 60 ° C. in the present embodiment).

  Next, the tank unit 30 communicates the hot water storage tank 31, the hot water discharge pipe 2 connected to the upper part of the hot water storage tank 31, the water supply pipe 1 connected to the lower part of the hot water storage tank 31, the water supply pipe 1 and the hot water supply pipe 2. And a hot water supply bypass pipe 37 that bypasses the hot water heater 10 and communicates the hot water discharge pipe 2 upstream and downstream of the hot water heater 10.

  Furthermore, the tank unit 30 includes a return thermistor 41 that detects the temperature of hot water supplied from the hot water storage tank 31 to the heat pump unit 60, and a hot water storage thermistor 42 that detects the temperature of hot water stored in the hot water storage tank 31 (the hot water storage temperature of the present invention). A hot water thermistor 33 provided in the vicinity of the upstream side of the connection point X between the hot water discharge pipe 2 and the water supply pipe 1, an incoming water flow rate sensor 43 that detects the flow rate of the water flow through the water supply pipe 1, and hot water storage The hot water storage tank flow rate sensor 46 for detecting the flow rate of hot water discharged from the tank 31 to the hot water discharge pipe 2, the incoming water thermistor 44 provided in the water supply pipe 1, and the flow rate of hot water supplied from the hot water storage tank 31 to the hot water discharge pipe 2 A hot water variable valve 34 to be changed, a water variable valve 35 to change the flow rate of water supplied from the water supply pipe 1 to the tap water pipe 2, and a pressure reducing valve with a check valve provided in the water supply pipe 1 0, a mixed thermistor 36 provided between the connection point X of the hot water pipe 2 and the water supply pipe 1 and the hot water bypass pipe 37, a bypass valve 38 for opening and closing the hot water bypass pipe 37, the hot water bypass pipe 37 and the hot water A hot water supply outlet thermistor 39 that detects the temperature of hot water supplied to the downstream side of the connection point Y with the pipe 2 is provided.

  Referring to FIG. 2, a tank controller 50, which is an electronic unit composed of a microcomputer or the like, includes a hot water storage thermistor 42, a hot water thermistor 33, a hot water thermistor 44, a mixed thermistor 36, a hot water outlet thermistor 39, and a return thermistor 41. A temperature detection signal is input.

  Further, the tank controller 50 receives flow rate detection signals from the incoming water flow rate sensor 43, the heating flow rate sensor 45, and the hot water storage tank flow rate sensor 46. The operation of the hot water variable valve 34, the water variable valve 35, and the bypass valve 38 is controlled by a control signal output from the tank controller 50.

  In the tank controller 50, a desired hot water supply temperature (hot water supply set temperature: temperature of hot water supplied from the outlet of the hot water discharge pipe 2) and bath temperature (bath set temperature: hot water filling pipe 18, which will be described later), according to the user's operation. A temperature switch (not shown) for setting the temperature of the hot water supplied to the bathtub via the hot water supply mode or a general hot water supply mode (hot water filling valve 19 described later is closed and hot water is supplied from the outlet of the hot water discharge pipe 2) A remote control 51 having a mode changeover switch (not shown) for switching between a hot water filling mode (a mode in which the hot water filling valve 19 is opened and hot water is supplied from the hot water filling pipe 18) to the bathtub. It is connected.

  By causing the microcomputer provided in the tank controller 50 to execute a control program for the tank unit 30, the tank controller 50 has a tapping time calculating means 52, a tapping elapsed time calculating means 53, an in-tank residence time calculating means 54, It functions as a tank residence time correction means 55, a hot water storage temperature control means 56, a sterilization processing means 57, and a mixed hot water temperature control means 58.

  The hot water storage temperature control means 56 monitors the temperature detected by the hot water storage thermistor 42 and transmits a heating instruction signal to the heat pump controller 80 in order to maintain the hot water in the hot water storage tank 31 at around 45 ° C. or 60 ° C.

  The sterilization processing means 57 performs a process (sterilization process) for sterilizing miscellaneous bacteria (eg, Legionella bacteria) in the hot water in the hot water storage tank 31. The sterilization process was continued for 96 hours (corresponding to the sterilization necessity judgment time of the present invention) for 96 hours (corresponding to the sterilization necessity judgment time of the present invention) with the temperature detected by the hot water storage thermistor 42 being 53 ° C. or lower. Sometimes, a hot water storage heating instruction signal is transmitted to the heat pump controller 80, and the hot water in the hot water storage tank 31 is heated to 58 ° C. (corresponding to the sterilization temperature of the present invention) or more for 1 hour or longer. Executed.

  The mixed hot water temperature control means 58 is supplied from the hot water storage tank 31 to the hot water pipe 2 by changing the openings of the hot water variable valve 34 and the water variable valve 35 so that the detected temperature of the mixed thermistor 36 becomes the hot water supply set temperature. Mixing temperature control is performed to adjust the mixing ratio of the hot water and the water supplied from the water supply pipe 1 to the hot water pipe 2.

  The hot water time calculating means 52, the hot water elapsed time calculating means 53, the in-tank residence time calculating means 54, and the in-tank residence time correcting means 55 are used to store the hot water in the hot water storage tank 31 (from the time when the sterilization process is executed). This is a configuration for calculating the residence time in the tank which is the residence time of hot water. Hereinafter, with reference to FIG. 3 to FIG. 5, the calculation process of the residence time of the hot water in the hot water storage tank 31 according to these configurations will be described.

  FIG. 3A shows a situation when hot water in the hot water storage tank 31 is used. The hot water discharge pipe 2 is connected to the upper part of the hot water storage tank 31, and the water supply pipe 1 is connected to the lower part of the hot water storage tank 31. Therefore, when hot water is supplied from the hot water storage tank 31 to the hot water discharge pipe 2, water is supplied from the water supply pipe 1 to the lower part of the hot water storage tank 31 corresponding to the amount W1 of the supplied hot water accordingly.

  Therefore, the residence time of the hot water in the hot water storage tank 31 becomes longer as it goes from the lower part to the upper part of the hot water storage tank 31. Therefore, the tank residence time calculation means 54 manages the residence time of the hot water in the hot water storage tank 31 by dividing it into three hot water layers L1, L2, and L3 in the vertical direction (corresponding to the predetermined number of the present invention). The residence time Ta in the tank of the uppermost hot water layer L1, the residence time T2 in the tank of the intermediate hot water layer L2, and the residence time T3 in the tank of the lower hot water layer L3 are calculated. The capacities of the hot water layers L1 to L3 are all equal to Vb (corresponding to the unit layer capacity of the present invention).

Further, as the hot water in the hot water storage tank 31 is used, the water layer expands upward, and when the water layer reaches the position of the hot water storage thermistor 42, the detected temperature of the hot water storage thermistor 42 becomes the target hot water supply temperature (general In the hot water supply mode, the temperature is lower than the hot water supply set temperature, and in the hot water filling mode, the temperature is lower than the bath set temperature. Then, the tank controller 50 determines that the hot water storage tank 31 has run out of hot water. Next, referring to FIG. 4, the tank residence time Ta of each of the hot water layers L1 to L3 by the tank residence time calculation means 54 is described. The procedure for calculating Tc will be described using a specific example.

The tank residence time calculation means 54 assigns the data of the tank residence times Ta to Tc of the hot water layers L1 to L3 to the array data A having three array elements a1 to a3. In the figure, A0 indicates the data when the sterilization process is completed (t ₁₀ ), and the residence times in the tank of the hot water layers L1 to L3 are all zero, which is the initial value ( A0 state).

When the sterilization process is completed, the hot water calculating unit 52 starts the timer C and starts integrating the supply flow rate of hot water from the hot water storage tank 31 to the hot water discharge pipe 2 detected by the hot water storage tank flow rate sensor 46 per unit time. . Then, the hot water time calculation means 52 calculates the time (t _{10 to} t ₁₁ ) T1 until the accumulated amount of hot water supplied from the hot water storage tank 31 to the hot water pipe 2 reaches the unit layer capacity Vb according to the time measured by the timer C. Ask. When the accumulated amount of hot water supplied from the hot water storage tank 31 to the hot water pipe 2 reaches the unit layer capacity Vb, the hot water time calculating means 52 resets and restarts the timer C.

  The tank residence time calculating means 54 calculates the time T1 until the accumulated amount of hot water supplied from the hot water storage tank 31 to the hot water discharge pipe 2 reaches the unit layer capacity Vb. The residence time Ta of the upper hot water layer L1 in the tank is set to a time obtained by adding the time T1 of the timer C to the residence time Tb (= 0) of the intermediate hot water layer L2 held in the tank a2 until then. Update and hold at a1.

  The tank residence time calculation means 54 sets the residence time Tb of the intermediate hot water layer L2 in the tank to the residence time Tc (= 0) in the tank of the lowermost hot water layer L3 held at a3 until then. The timer C is updated to a time (T1) obtained by adding the time measured (T1), and held at a2. Further, the tank residence time calculating means 54 updates the residence time Tc in the tank of the lowermost hot water layer L3 to the time measured by the timer C (T1) and holds it at a3 (state A1). Then, the hot water calculating means 52 resets the timer C and restarts it.

  In this way, when the time until the accumulated amount of hot water reaches the unit layer capacity Vb is calculated by the tapping time calculating means 52, the in-tank residence time calculating means 54 is a hot water layer other than the lowest hot water layer L3. For L1 and L2, the residence times Ta and Tb in the tank are updated to the residence time in the tank of the lower hot water layer that was held in a2 and a3 until then, and are held in a1 and a2. Further, the tapping time calculating means 52 updates the residence time Tc in the tank of the lowermost hot water layer L3 to the time measured by the timer C and holds it at a3 (in-tank residence time update process).

The in-tank residence time calculation means 54 executes the in-tank residence time update process every time the hot water calculation time 52 calculates the time until the accumulated amount of hot water reaches the unit layer capacity Vb. In the example of FIG. 4, when the accumulated amount of hot water next reaches the unit layer capacity Vb (t ₁₂ ), the residence time Ta in the tank of the uppermost hot water layer L1 has been maintained at a2 until then. It is updated to a time (T1 + T2) obtained by adding the time measured by the timer C (T2) to the residence time Tb (= T1) in the hot water layer L2 of the layer.

  Also, the residence time Tb in the tank of the intermediate hot water layer L2 is set to the time Tc (T2) of the timer C, which is equal to the residence time Tc (= T1) in the tank of the lowermost hot water layer L3 that has been held at a3. It is updated to the time (T1 + T2) obtained by adding. Furthermore, the residence time Tc in the tank of the lowermost hot water layer L3 is updated to the time measured by the timer C (T2) (state A2).

Next, when the accumulated amount of hot water reaches the unit layer capacity Vb (t ₁₃ ), the residence time Ta in the tank of the uppermost hot water layer L1 is the intermediate hot water layer that has been held at a2 until then. It is updated to a time (T1 + T2 + T3) obtained by adding the time measured by the timer C (T3) to the L2 tank residence time Tb (= T1 + T2).

  Further, the retention time Tb in the tank of the intermediate hot water layer L2 is set to the time Tc (T3) of the timer C, which is equal to the retention time Tc (= T2) in the tank of the lowermost hot water layer L3 that has been held at a3. Is updated to the time (T2 + T3) obtained by adding. Furthermore, the residence time Tc in the tank of the lowermost hot water layer L3 is updated to the time measured by the timer C (T3) (state A3).

Next, the hot water elapsed time calculating means 53 determines that the accumulated amount of hot water supplied from the hot water storage tank 31 to the hot water pipe 2 reaches the unit layer capacity Vb, and the tanks of the hot water layers L1 to L3 by the tank residence time update process. The elapsed time t _n from when the internal residence times Ta to Tc are updated until the next in-tank residence time update process is performed is calculated from the time Tm of the timer C.

Then, the tank residence time calculation means 54 performs each of the data stored in a1 to a3 after performing the tank residence time update process at a certain time until the next tank residence time update process. The time obtained by adding the elapsed time t _n calculated by the tapping elapsed time calculating means 53 to the residence time Ta to Tc in the tank of the hot water layers L1 to L3 is the residence time Ta to Tc in the tank of each of the hot water layers L1 to L3. To do.

For example, in the state of figure A3, when the elapsed time calculated by the exit water elapsed time calculating means 53 is t _n, as shown in the figure B, the tank residence time of the hot water layers L1 to L3 ta Tc is, Ta = T1 + T2 + T3 + t n, Tb = T2 + T3 + t n, the Tc = T3 + _{t n.}

  Therefore, the residence time Ta in the tank of the uppermost hot water layer L1 in the hot water storage tank 31 is a time calculated by the following equation (1).

Ta = T _n−3 + T _n−2 + T _n−1 + t _n (1)
However, n is a positive integer, n = 1 when sterilization is performed, and is counted up by one each time the accumulated amount of hot water supplied from the hot water storage tank 31 to the hot water discharge pipe 2 reaches the unit layer capacity Vb. T _n-1 : Time required for integration of the unit layer capacity Vb before the first time, time required for integration of the unit layer capacity Vb two times before, required for integration of the unit layer capacity Vb three times before Time, t _n : elapsed time calculated by the tapping elapsed time calculating means.

  Next, when the hot water storage tank temperature adjustment process for heating the hot water in the hot water storage tank 31 to 45 ° C. is executed by the hot water storage temperature control means 56, the in-tank residence time correcting means 55 performs the elements a 1 to a 3 of the array A. The in-tank residence time correction process for correcting the in-tank residence times Ta to Tc of the hot water layers L1 to L3 held in the tank is performed.

  Here, FIG.3 (b) shows the condition when the hot water in the hot water storage tank 31 is heated by the hot water storage tank temperature control process. During execution of the hot water storage tank temperature adjustment process, hot water in the hot water storage tank 31 is supplied to the heat pump unit 60 via the heating return pipe 67 connected to the lower part of the hot water storage tank 31 and heated by the heat pump unit. Hot water is returned to the hot water storage tank 31 via the heating forward pipe 64.

  In this way, when the hot water staying in the lower part of the hot water storage tank 31 is supplied to the upper part of the hot water storage tank 31, the hot water in the lower part whose residence time is short in the tank moves to the upper part. The distribution of the hot water residence time at 31 changes. Therefore, as shown in FIG. 5, the in-tank residence time correcting means 55 corrects the in-tank residence times Ta to Tc of the hot water layers L1 to L3 held in the elements a1 to a3 of the array A. Do.

FIG. 5 shows a case where the hot water heating process in the hot water storage tank 31 is started by the hot water storage temperature control means 56 in the state of A3 in FIG. When the hot water storage tank temperature control process is started by the hot water storage temperature control means 56 (t ₂₀ ), the tank residence time correcting means 55 stores the hot water layers L1 to L3 according to the data held in the a1 to a3 at that time. the tank residence time Ta to Tc, by adding the elapsed time t _n calculated by tapping the elapsed time calculating means 53, held in a1 to a3 (A4 state of).

The in-tank residence time correcting means 55 integrates the flow rate per unit time of hot water returning from the hot water storage tank 31 to the hot water storage tank 31 via the condenser 72 detected by the heating flow rate sensor 45. When the accumulated amount of hot water (heating circulation amount) reaches the unit layer capacity Vb (t ₂₁ ), the tank residence time correcting means 55 determines the residence time Ta in the tank of the uppermost hot water layer L1 until then. It replaces with the residence time Tc in the tank of the lowermost hot water layer L3 held in a3 and holds it in a1.

  In addition, the tank residence time correction means 55 for the other hot water layers L2 and L3, the residence times Tb and Tc in the tanks are retained in the tank of the upper hot water layer that has been held at a1 and a2 until then. It replaces with time Ta and Tb, and hold | maintains at a2 and a3 (state of A5). Thereby, the residence time Ta-Tc in the tank of each hot water layer L1-L3 is corrected according to the heating of the hot water accompanying the circulation of the hot water from the lower part to the upper part of the hot water storage tank 31.

In addition, the heating of the hot water in the hot water storage tank 31 is completed in the state of A5, and then the amount of hot water supplied from the hot water storage tank 31 to the hot water discharge pipe 2 becomes the unit layer capacity Vb, and the hot water time calculation means 52 causes the unit layer to be heated. When the time T4 required for discharging the hot water of the capacity Vb is calculated (t ₂₀ ), the above-described tank residence time update process is executed by the tank residence time calculation means 54.

  For the uppermost hot water layers L1 and L2, the retention times Ta and Tb in the tank are the same as the retention times in the tank of the lower hot water layer held in a2 and a3 until then, and the time T4 measured by the timer C is reached. Is updated to the time obtained by adding, and held in a1 and a2. Further, the lowermost hot water layer L3 is updated to the time T4 counted by the timer C and held at a3 (state A6).

  Next, the mixed hot water temperature control means 58, when the sterilization processing is not performed by the sterilization processing means 57, when the detected temperature of the hot water storage thermistor 42 is higher than the target hot water supply temperature (a state where no hot water is cut off), The hot water amount variable valve 34 and the water amount variable valve 35 are set so that the detected temperature of the mixed thermistor 36 or the hot water outlet thermistor 39 becomes the target hot water supply temperature when water flow exceeding a predetermined lower limit flow rate is detected by the incoming water flow rate sensor 43. Performs mixed temperature control to control the opening. At this time, the tank controller 50 opens the bypass valve 38 in the general hot water supply mode, and closes the bypass valve 38 in the hot water filling mode.

  On the other hand, when the detected temperature of the hot water storage thermistor 42 is equal to or lower than the target hot water supply temperature (a state where hot water has run out), when the incoming water flow rate sensor 43 detects water flow exceeding the lower limit water amount, the tank controller 50 The valve 38 is closed to supply all hot water from the hot water storage tank 31 and the water supply pipe 1 to the water heater 10. In this case, in the water heater 10, heating temperature control described later is executed.

  Next, the water heater 10 bypasses the heat exchanger 11 provided in the middle of the hot water pipe 2, the burner 12 which heats the heat exchanger 11, and the heat exchanger 11, and connects the hot water pipe 2 to the heat exchanger. 11, a hot water supply bypass pipe 13 communicating between the upstream side and the downstream side, and a hot water filling pipe 18 connecting a bathtub (not shown) and the hot water supply pipe 2 on the downstream side of the connection point Z between the hot water supply pipe 2 and the hot water supply bypass pipe 13. It has.

  The outlet pipe 2 includes a bypass servo valve 14 that changes the opening degree of the hot water supply bypass pipe 13, a water amount servo 15 that adjusts the flow rate of hot water supplied to the hot water heater 10, a heat exchanger 11, and a hot water supply bypass pipe 13. A hot water supply flow rate sensor 21 that detects the flow rate of hot water supplied, a hot water heater thermistor 16 that detects the temperature of hot water supplied downstream of the connection point Z between the hot water discharge pipe 2 and the hot water supply bypass pipe 13, and a check valve 17. And are provided. The hot water filling pipe 18 is provided with a hot water filling flow rate sensor 22 for detecting the flow rate of the hot water filling pipe 18 and a hot water filling valve 19 for opening and closing the hot water filling pipe 18.

  Then, a temperature detection signal from the hot water supply thermistor 16 and a flow rate detection signal from the hot water supply flow rate sensor 21 and the hot water flow rate sensor 22 are input to the hot water supply controller 20 which is an electronic unit composed of a microcomputer or the like. Further, the operation of the bypass servo 14, the water amount servo 15, the burner 12, and the hot water filling valve 19 is controlled by a control signal output from the hot water supply controller 20.

  The hot water supply controller 20 is communicably connected to the tank controller 50 and enters a heating permission state when receiving a signal for instructing heating from the tank controller 50. Then, the heating temperature control for controlling the combustion amount of the burner 12 so that the detected temperature of the water heater thermistor 16 becomes the target hot water supply temperature when the hot water supply flow sensor 21 detects water flow exceeding a predetermined lower limit flow rate. Execute control. Further, when a signal for instructing heating is received from the tank controller 50, the heating is prohibited and execution of the heating temperature control is prohibited.

  In addition, the hot water supply controller 20 opens the hot water filling valve 19 when the hot water filling operation for supplying a predetermined amount of hot water to a bathtub (not shown) (hot water filling mode) is performed by the hot water filling flow rate sensor 22. Accumulate the amount of hot water supplied to the detected bathtub. When the cumulative amount of hot water supplied to the bathtub reaches the predetermined amount, the hot water filling valve 19 is closed to end the hot water filling operation.

  Next, the operation of the tank controller 50 will be described according to the flowcharts shown in FIGS.

  When the power of the tank unit 30 is turned on in STEP 1 of FIG. 6, the process proceeds to STEP 2, and the tank controller 50 fully closes the hot water variable valve 34 and fully opens the water variable valve 35. Then, the tank controller 50 prohibits heating by the water heater 10 in the next STEP 3 and determines whether or not the detected temperature of the hot water storage thermistor 42 is higher than 35 ° C. in the next STEP 4.

  Here, when the detected temperature of the hot water storage thermistor 42 is lower than 35 ° C. in STEP 4, there is a possibility that the temperature of the hot water in the hot water storage tank 31 continues to be low and the germs in the hot water are increasing. Therefore, in this case, it is necessary to sterilize the hot water in the hot water storage tank 31 immediately. Therefore, in this case, the process branches to STEP 30, and the tank controller 50 turns on (sets) a refresh flag (indicated as refresh F in the figure) that instructs sterilization of the hot water in the hot water storage tank 31. Then, the process proceeds to STEP 6, and the tank controller 50 proceeds to STEP 7 with the heating of the hot water in the hot water storage tank 31 being stopped.

  On the other hand, when the detected temperature of the hot water storage thermistor 42 is 35 ° C. or higher in STEP 4, the power supply to the tank unit 30 is temporarily interrupted due to a power failure or the like, and the hot water temperature in the hot water storage tank 31 does not drop so much. It can be assumed that the power supply has been resumed. In this case, it is not necessary to sterilize the hot water in the hot water storage tank 31 immediately. Therefore, the process proceeds to STEP 5 and the tank controller 50 turns off (resets) the refresh flag. Then, the process proceeds to STEP 6, and the tank controller 50 proceeds to STEP 7 with the heating of the hot water in the hot water storage tank 31 being stopped.

  In STEP 7, the tank controller 50 determines whether or not the refresh flag is in an ON state. If the refresh flag is in the ON state, the process branches to STEP 40. If the refresh flag is not in the ON state, the process proceeds to STEP 8. In STEP 40, the tank controller 50 fully closes the hot water amount variable valve 34 and fully opens the water amount variable valve 35 to prohibit the use of hot water in the hot water storage tank 31.

  In STEP 8, the tank controller 50 determines whether or not an operation switch (not shown) provided in the remote controller 51 is in an ON state. When the operation switch is in the ON state, the process proceeds to STEP 9, and when the operation switch is not in the ON state, the process branches to STEP 6. The operation switch is a switch for instructing switching between an operation state in which the hot water supply operation by the hot water supply system is possible and a standby state in which the hot water supply operation by the hot water supply system is impossible, and is operated when the operation switch is in the ON state. It becomes a state.

  When the operation switch is in the ON state, the process proceeds to STEP 9, and the tank controller 50 selects either the high temperature hot water storage flag (indicated as high temperature hot water storage F in the figure) for instructing hot water storage at a high temperature (60 ° C.) or the refresh flag. It is determined whether or not it is in an ON state. When either the high-temperature hot water storage flag or the refresh flag is in the ON state, the process proceeds to STEP 50, and the tank controller 50 transmits a heating instruction signal for instructing hot water storage at 60 ° C. to the heat pump controller 80.

  Thereby, the heating by the heat pump 70 is performed, and the temperature of the hot water in the hot water storage tank 31 is maintained around 60 ° C. This set temperature of 60 ° C. is to cope with sterilization of hot water in the hot water storage tank 31 and use of a large amount of hot water, and corresponds to the sterilization temperature of the present invention.

  On the other hand, when both the high temperature hot water storage flag and the refresh flag are not in the ON state in STEP 9, the process proceeds to STEP 10. Then, the tank controller 50 transmits a heating instruction signal for instructing hot water storage at 45 ° C. to the heat pump controller 80. Thereby, the heating by the heat pump 70 is performed, and the temperature of the hot water in the hot water storage tank 31 is maintained at around 45 ° C. The set temperature of 45 ° C. is for performing efficient hot water storage by suppressing the heat dissipation of the hot water in the hot water storage tank 31.

  In subsequent STEP 11, the tank controller 50 determines whether or not the water flow rate sensor 43 is in a water flow state in which water flow exceeding the lower limit flow rate is detected. And when it is a water flow state, it progresses to STE12 of FIG. 3, and when it is not a water flow state, it returns to STEP7.

  STEP 12 to STEP 15, STEP 70 to STEP 71, and STEP 60 to STEP 61 in FIG. 3 are performed at a target hot water supply temperature (a hot water supply set temperature in the general hot water supply mode, or a bath set temperature in the hot water filling mode) by mixing temperature control or heating temperature control. This is a process for supplying hot water.

  In STEP 12, the tank controller 50 determines whether or not the refresh flag is ON. When the refresh flag is ON, the process branches to STEP 60, and the tank controller 50 transmits a signal for instructing heating to the hot water supply controller 20. In subsequent STEP 61, the tank controller 50 fully closes the hot water variable valve 34, fully opens the water variable valve 35, and proceeds to STEP 16.

  By the processing of STEP 60 and STEP 61, heating by the water heater 10 is permitted in a state where the hot water variable valve 34 is fully closed and the use of hot water in the hot water storage tank 31 is prohibited. The combustion amount of the burner 12 and the bypass servo valve 14 are adjusted by the hot water supply controller 20 so that the detected temperature of the water heater thermistor 16 becomes the target hot water supply temperature (the hot water supply set temperature in the general hot water supply mode and the bath set temperature in the hot water filling mode). Is controlled (heating temperature control).

  On the other hand, when the refresh flag is not in the ON state in STEP 12, the process proceeds to STEP 13, and the tank controller 50 is in the general hot water supply mode and has run out of hot water (the temperature detected by the hot water storage thermistor 42 is equal to or lower than the target hot water temperature). Judge whether there is.

  When it is in the general hot water supply mode and no hot water has run out, the process proceeds to STEP 14, and the tank controller 50 transmits a signal for instructing prohibition of heating to the hot water supply controller 20. Thereby, the heating by the water heater 10 is prohibited.

  Further, the subsequent STEP 15 is processing by the mixed hot water temperature control means 58. The mixed hot water temperature control means 58 changes the opening of the hot water volume variable valve 34 and the water volume variable valve 35 so that the detected temperature of the mixed thermistor 36 becomes the target hot water supply temperature (hot water supply set temperature). The mixing ratio of hot water supplied to the pipe 2 and water supplied from the water supply pipe 1 to the hot water discharge pipe 2 is adjusted (mixing temperature control), and the process proceeds to STEP16.

  In STEP 13, when the hot water filling mode is selected or when the hot water storage tank 31 has run out, the process branches to STEP 70. And the tank controller 50 transmits the signal which instruct | indicates heating permission with respect to the hot water supply controller 20, and, thereby, the heating by the hot water heater 10 is permitted.

  In subsequent STEP 71, the opening amounts of the hot water variable valve 34 and the water variable valve 35 are changed so that the mixed set temperature set by the following equation (2) is obtained, and the hot water storage tank 31 supplies the hot water pipe 2 to the hot water pipe 31. The mixing ratio between the hot water to be supplied and the water supplied from the water supply pipe 1 to the hot water supply pipe 2 is adjusted, and the process proceeds to STEP16.

Mixing set temperature = target hot water temperature-minimum capacity temperature (2)
However, hot water supply with a target hot water supply temperature: hot water supply set temperature in the general hot water supply mode, bath set temperature in the hot water filling mode, and minimum capacity temperature: current water amount (current water flow rate detected by the hot water supply flow sensor 21) The rising temperature of hot water when heated at a minimum capacity by 10.

  In this case, the hot water controlled to the mixing temperature of the above formula (2) in STEP 71 is supplied to the hot water heater 10, and the hot water controller 20 determines that the detected temperature of the hot water heater thermistor 16 is the target hot water temperature (in the general hot water supply mode, the hot water supply setting). The combustion amount of the burner 12 and the opening of the bypass servo valve 14 are controlled (heating temperature control) so that the temperature becomes the bath setting temperature in the hot water filling mode.

  In the next STEP 16, the tank controller 50 determines whether or not the water flow rate sensor 43 is in a water stop state in which water flow exceeding the lower limit flow rate is not detected. When the water stop state is reached, the process proceeds to STEP 17 where the tank controller 50 stops the hot water variable valve 34 (maintains the current opening), and stops the water variable valve 35 (follows the current opening) at STEP 18. Hold. Further, in the next STEP 19, the tank controller 50 transmits a signal instructing prohibition of heating to the hot water supply controller 20, and returns to STEP 7 in FIG.

  Next, according to the flowchart shown in FIG. 8, the refresh flag ON / OFF (set / reset) processing by the sterilization processing means 57 will be described. Note that the processes according to the flowcharts shown in FIGS. 8 to 9 are executed in parallel with the processes according to the flowcharts shown in FIGS.

  The sterilization processing means 57 determines in STEP 80 whether or not the refresh flag is ON. If the refresh flag is not ON, the process proceeds to STEP 81. In STEP 81, the sterilization processing means 57 determines that the uppermost hot water layer L1 residence time calculated by the in-tank residence time calculation means 54 in the state where the hot water storage temperature (detected temperature of the hot water storage thermistor 42) is lower than 53 degrees. When Ta reaches 96 hours (corresponding to the sterilization necessity determination time of the present invention) or more, the process proceeds to STEP 82, the refresh flag is turned on, and the process proceeds to STEP 80.

  Note that, in STEP 81, the condition that the hot water storage temperature is lower than 53 ° C. continues for 96 hours or more, because low temperature hot water has been stored in the hot water storage tank 31 for a long time. It is a condition assumed that there is a possibility that the existence ratio of the above may exceed a preset allowable level.

  On the other hand, when the refresh flag is ON in STEP80, the process proceeds to STEP90. The sterilization means 57 proceeds to STEP 91 and proceeds to STEP 91 when the state where the hot water storage temperature (detected temperature of the hot water storage thermistor 42) is 58 ° C. (corresponding to the sterilization temperature of the present invention) or more continues for one hour or more. And go to STEP80.

  In STEP 90, when the state where the hot water storage temperature is 58 ° C. or higher continues for 1 hour or longer, the condition that the germs exceeding the allowable level in the hot water in the hot water storage tank 31 are assumed to be killed by heating is assumed. It is. In this manner, the refresh flag is maintained in the ON state until the condition of STEP 90 is satisfied by the sterilization processing means 57, and hot water storage heating instructing the heat pump controller 80 to store hot water at 60 ° C. An instruction signal is transmitted. The hot water in the hot water storage tank 31 is heated by the heat pump 70 and sterilized.

  Next, the high temperature hot water storage flag ON / OFF (set / reset) process will be described with reference to the flowchart shown in FIG.

  The tank controller 50 acquires the current time data from the time measuring unit (not shown) in STEP 120. In subsequent STEP 121, the tank controller 50 determines whether or not the current time is in the high temperature setting time zone. Here, the high temperature setting time zone is set from the evening when the amount of hot water used is assumed to increase to bedtime (for example, from 18:00 to 22:00). The high temperature setting time zone is set by the remote controller 51.

  When the current time is the high temperature set time zone, the process branches to STEP 130, and the tank controller 50 turns on (sets) the high temperature hot water storage flag and returns to STEP 120. Further, when the current time is not the high temperature set time zone, the routine proceeds to STEP 122, and the tank controller 50 determines whether or not the hot water filling operation is being executed.

  When the hot water filling operation is being executed, the process branches to STEP 130, where the tank controller 50 turns on (sets) the high temperature hot water storage flag and returns to STEP 120. When the hot water filling operation is not being executed, the process proceeds to STEP 123, where the tank controller 50 turns off the high temperature hot water storage flag and returns to STEP 120.

  9, the hot water in the hot water storage tank 31 is stored at a high temperature (60 ° C.) when the hot water usage increases and during the hot water filling operation. Thus, the mixed temperature control can be executed.

  In the present embodiment, the hot water supply system including the hot water bypass pipe 37 that bypasses the hot water heater 10 and the bypass valve 38 that opens and closes the hot water bypass pipe 37 is shown. However, the hot water bypass pipe and the bypass valve that opens and closes the hot water bypass pipe are provided. The effect can be obtained by applying the present invention to a hot water supply system that is not provided.

  In the present embodiment, the hot water supply system that includes the hot water filling pipe 18 and the hot water filling valve 19 and performs hot water supply in the general hot water supply mode and the hot water filling mode has been described. The present invention can also be applied when only hot water supply is performed.

  Moreover, although the hot water supply system which uses a heat pump as a heating means of the hot water in the hot water storage tank 31 was shown in this Embodiment, you may use other heating means, such as a solar system.

  Moreover, although the hot water supply system provided with the hot water heater 10 in the middle of the hot water discharge pipe 2 is shown in the present embodiment, the present invention can be applied even to a hot water supply system that does not include the hot water heater 10.

  In the present embodiment, the tank residence time calculation means 54 divides the hot water in the hot water storage tank 31 into three hot water layers and calculates the residence time in the tank of each hot water layer, but two or four or more. It is also possible to calculate the residence time of each hot water layer in the tank separately for each hot water layer.

  Further, in the present embodiment, the elapsed time from when the remaining time in the tank is updated is calculated by the tapping elapsed time calculating means 53, and the remaining time in the tank calculating means 54 adds the elapsed time. Although the residence time of each hot water layer in the tank is calculated, the effect of the present invention can be obtained even when the elapsed time is not added.

  DESCRIPTION OF SYMBOLS 1 ... Water supply pipe, 2 ... Hot water supply pipe, 7 ... Water supply branch pipe, 10 ... Hot water heater, 14 ... Bypass servo valve, 20 ... Hot water supply controller, 30 ... Tank unit, 31 ... Hot water storage tank, 33 ... Hot water thermistor, 34 ... Hot water quantity Variable valve, 35 ... Water amount variable valve, 36 ... Mixing thermistor, 37 ... Hot water bypass pipe, 38 ... Bypass valve, 42 ... Hot water storage thermistor, 44 ... Hot water thermistor, 45 ... Heat flow sensor, 46 ... Hot water tank flow sensor, 50 ... Tank controller 51... Remote controller 52. Hot water time calculation means 53. Hot water elapsed time calculation means 54. Retention time calculation means in tank 55 55 Residence time correction means in tank 56 56 Hot water temperature control means 57 57 Sterilization Processing means 58 ... Mixed hot water temperature control means 60 ... Heat pump unit 64 ... Heating forward pipe 67 ... Heating return pipe 70 ... Heat pump , 80 ... heat pump controller.

Claims (3)

A hot water storage tank,
A hot water pipe connected to the upper part of the hot water storage tank and supplied with hot water from the hot water storage tank,
A water supply pipe connected to the lower part of the hot water storage tank to supply water to the hot water storage tank;
A heating unit for heating hot water in the hot water storage tank;
A hot water tank flow rate sensor for detecting the flow rate of water supplied from the water supply pipe to the hot water storage tank or the flow rate of hot water supplied from the hot water storage tank to the hot water discharge pipe;
Based on the detected flow rate of the hot water tank flow rate sensor, the amount of water supplied from the water supply pipe to the hot water storage tank or the amount of hot water supplied from the hot water storage tank to the hot water discharge pipe is integrated, and the capacity of the hot water storage tank A tapping time calculating means for measuring unit layer capacity tapping time, which is a time required when hot water for a unit layer capacity divided by a predetermined number is supplied from the hot water storage tank to the tapping pipe;
Calculated elapsed hot water time for measuring the elapsed time from the time when the unit layer capacity hot water time is calculated at a predetermined time by the hot water time calculating means until the time when the unit layer capacity hot water time is calculated by the hot water time calculating means. Means,
The retention time in the tank, which is the time during which hot water in the hot water storage tank stays in the hot water storage tank, for each of the predetermined number of hot water layers stacked in the vertical direction in the hot water storage tank with the unit layer capacity. Each time the unit layer capacity hot water time is calculated by the hot water time calculating means, for each hot water layer other than the lowest layer, the time of the calculated unit layer hot water time of the lower hot water layer is measured. The time obtained by adding the calculated unit layer hot water time to the residence time in the tank at the time of starting is used as the own tank residence time, and for the lowermost hot water layer, the calculated unit layer hot water time is The tank residence time update process, which is the own residence time in the tank, is performed, and then the unit layer hot water discharge time is calculated by the hot water discharge time calculating means until the unit layer hot water discharge time is calculated. Upper water layer The residence time in the tank, by adding the elapsed time calculated by the tapping elapsed time calculation means, and the tank residence time calculating means for calculating the tank residence time of the uppermost hot water layer,
When the residence time of the uppermost hot water layer in the tank exceeds the sterilization necessity determination time set on the assumption that germs propagate in the hot water in the hot water tank, the heating means stores the hot water tank. A hot water supply system comprising: sterilization processing means for performing sterilization processing for heating the hot water in the interior to a predetermined sterilization temperature or higher. The hot water supply system according to claim 1,
The heating unit is connected to the heating return pipe connected to the lower part of the hot water storage tank, the heating forward pipe connected to the upper part of the hot water storage tank, the heating return pipe and the heating forward pipe, and the heating return pipe Heating means for heating the hot water in the hot water tank supplied through the heating tank and returning the hot water to the hot water storage tank through the heating forward pipe,
The tank residence time calculation means performs the residence time update process in the tank after the residence time update process in the tank until the next unit hot water discharge time is calculated by the hot water calculation means. Add the elapsed time calculated by the elapsed hot water time to the set residence time of each hot water layer in the tank to calculate the residence time of each hot water layer in the tank,
A hot water storage temperature sensor for detecting the temperature of hot water in the hot water storage tank;
Hot water storage temperature control for performing hot water storage tank temperature adjustment processing for heating hot water in the hot water storage tank to the predetermined temperature by the heating means when the temperature detected by the hot water storage temperature sensor is lower than a predetermined temperature lower than the sterilization temperature. Means,
A heating flow rate sensor for detecting a flow rate of hot water flowing through the heating return pipe and the heating forward pipe;
Based on the flow rate detected by the heating flow sensor, the amount of hot water returning from the hot water storage tank to the hot water storage tank via the heating unit is integrated, and the hot water storage tank returns to the hot water storage tank via the heating unit. Each time the accumulated amount of hot water increases by the unit layer capacity, the residence time in the tank of the uppermost hot water layer is calculated as the residence time in the tank of the uppermost hot water layer with respect to the residence time in the tank of each hot water layer calculated by the tank residence time calculation means. Retention time in the tank where the hot water layer stays in the tank, and for each hot water layer other than the uppermost layer, the stay time in the tank is set so that the stay time in the tank of the upper hot water layer is in the tank. A hot water supply system comprising correction means. In the hot water supply system according to claim 1 or claim 2,
A water supply branch pipe connecting the water supply pipe and the hot water supply pipe;
A water amount variable valve provided in the water supply branch pipe to change the opening of the water supply branch pipe;
A hot water variable valve that is provided between a connection portion between the hot water storage pipe and the hot water storage tank and a connection portion between the water supply pipe and changes the opening of the hot water supply pipe;
A hot water heater that is provided in the middle of the hot water pipe on the downstream side of the connecting portion between the hot water pipe and the water supply pipe, and that heats hot water flowing through the hot water pipe;
The hot water supply system is characterized in that the sterilization means closes the hot water variable valve when performing the sterilization process.

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