JP2014089009A - Hot water storage and hot water supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot water storage and hot water supply system capable of circulating high-temperature hot water heated by an auxiliary heat source device and guided by a heat utilizing circulation circuit to a heating circulation circuit without destroying thermal stratification in a hot water storage tank as freezing preventive operation in the heating circulation circuit.SOLUTION: An upstream end portion of a heating circulation circuit 9 extending from a lower part of a hot water storage tank 3 and a downstream end portion of a heat utilizing circulation circuit 8 returned to the lower part of the hot water storage tank 3 are configured by a common lower pipe part 12 extending from the lower part of the hot water storage tank and can be communicated/branched each other on a junction 13. In circulation operation of the heating circulation circuit 9 during freezing preventive operation, a discharge flow rate of circulation pumps 93 and 62 and a passage flow rate of a three-way selector valve 61 are changed and set so that a circulation flow rate of circulating hot water returned to the upper part of the hot water storage tank 3 becomes an extraction flow rate or more extracted from the upper part of the hot water storage tank 3 to the heat utilizing circulation circuit 8.

Description

  The present invention relates to a hot water storage and hot water supply system having a hot water storage tank, and in particular, for circulating heating in which hot water is taken out from the lower part of the hot water tank and heated using the exhaust heat of an external heat source and returned to the upper part of the hot water tank. The present invention relates to a hot water storage hot water system in which a freeze prevention operation is performed for a heating circulation circuit.

  Patent Document 1 shown below includes a hot water storage tank for storing a part of the cooling water to store heat while heating the heating medium with heat (exhaust heat generated by power generation) of the cooling water of the fuel cell. System is described. In this, the cooling water from the fuel cell is circulated and supplied to the primary side of the heat exchanger through the cooling water circuit, while the heating medium from the heating device is supplied to the secondary side of the heat exchanger through the heating medium circuit. The hot water tank is interposed in the cooling water circulation path, and the auxiliary heat source device is interposed in the heating medium circulation path. Then, when the necessity of the freeze prevention operation occurs, by performing the freeze prevention operation of circulating the heating medium in the heating medium circulation path while operating the auxiliary heat source apparatus, the heating medium heated by the auxiliary heat source apparatus It is described that heat is transferred to the cooling water in the cooling water circuit via a heat exchanger, thereby preventing the cooling water circuit from freezing.

JP 2007-132612 A

  By the way, the hot water in the hot water tank is stored in the hot water tank by heat exchange heat using the exhaust heat from an external heat source such as a fuel cell, and the hot water is discharged for hot water supply or the heat from the heating medium, etc. A hot water storage hot water system that is used as a heat source for exchange heating has been considered. For example, as shown in FIG. 4, the external heat source device 2 for supplying exhaust heat to the heat source side of the heat exchanger 22 and the hot water in the hot water tank 300 are taken out from the lower side to the heated side of the heat exchanger 22. A heating circulation circuit 900 for returning and storing hot water heated and exchanged to the upper part of the hot water tank 300 and a hot water circuit 500 for discharging hot hot water taken out from the upper part of the hot water tank 300 for hot water supply. Then, after branching off from the hot water supply circuit 500, hot water is supplied as a heat source to, for example, the heat exchanger 801 for heating the heating medium, and the hot water having a lowered temperature after the heat exchange is stored in the hot water tank 300. A heat utilization circulation circuit 800 that utilizes the heat of the hot water in the hot water tank 300 so as to return to the lower part is provided. In this hot water storage hot water supply system, in relation to the hot water storage tank 3, the heating circulation circuit 900 and the heat utilization circulation circuit 800 are provided as separate circuits independently of each other.

  However, in this hot water storage and hot water supply system, when the freeze prevention operation is performed when the heating operation by the heating circulation circuit 900 is stopped, the hot water heated by the auxiliary heat source device 600 is temporarily placed in the lower part of the hot water tank 300 to prevent freezing. Due to the inflow, the temperature stratification formed in the hot water storage tank 300 is destroyed, and when the heating operation by the heating circulation circuit 900 is restarted thereafter, or to the hot water supply circuit 500 for hot water supply. There is a risk of inconvenience such as inability to operate at the time of hot water. That is, the auxiliary heat source device 600 interposed in the hot water circuit 500 (heat utilization circuit 800) is operated to heat the hot water taken out from the upper part of the hot water tank 300, and then the hot water tank 300 is passed through the heat utilization circuit 800. Let it flow into the bottom. Then, the heated hot water once flowing into the lower part of the hot water tank 300 is passed through the heating circuit 900 by operating the circulation pump 901 of the heating circuit 900, so that the freeze prevention operation is performed. Normally, due to the heating operation by the heating circuit 900, temperature stratification is formed such that hot water in the hot water tank 300 is stored in the upper part and becomes hot in the lower part. For this reason, hot water can be used by supplying water from the upper part of the hot water tank 300 for hot water supply, while low temperature hot water is supplied from the lower part of the hot water tank 300 to the external heat source device 2 for heating operation. Thus, an effect of efficiently recovering exhaust heat can be obtained. However, when hot water heated by the auxiliary heat source device 600 flows into the lower part of the hot water tank 300 from the heat utilization circulation circuit 800, the temperature stratification in the hot water tank 300 is destroyed, and the hot water tank 300 is heated for hot water. The temperature of the hot water taken out from the upper part decreases, and the temperature of the hot water taken out from the lower part of the hot water storage tank 300 increases due to the reheating operation, so that the external heat source device 2 cannot efficiently perform heat exchange heating. It will lead to a situation.

  The present invention has been made in view of such circumstances, and an object of the present invention is to take out hot water in the hot water tank from the lower part, heat it with an external heat source device, and store it in the upper part of the hot water tank. Heating circulation circuit for returning hot water whose temperature has been lowered to the lower part of the hot water tank by using high temperature hot water taken out from the upper part of the hot water tank as a heat source for heat exchange heating of the heating medium, for example In a hot water storage hot water supply system equipped with a high temperature hot water heated by an auxiliary heat source device and guided by a heat utilization circulation circuit, as a freeze prevention operation in the heating circulation circuit when the heating operation by the heating circulation circuit is stopped, An object of the present invention is to provide a hot water storage and hot water supply system that can be circulated in a heating circulation circuit without breaking the temperature stratification.

  In order to achieve the above object, in the present invention, a heating circuit that heats hot water taken out from the lower part of the hot water tank with an external heat source device and returns it to the upper part of the hot water tank, and hot water taken out from the upper part of the hot water tank A hot water supply circuit for discharging water to a hot water tap provided in the heat source, and a heat utilization circulation circuit that branches from the hot water supply circuit and returns to the lower part of the hot water storage tank. The heat utilization circulation circuit includes an auxiliary heat source device and heat utilization. A heat exchanger for heating an object, and an upstream end portion of the heating circulation circuit extending from a lower portion of the hot water tank and a downstream end portion of the heat utilization circulation circuit returning to the lower portion of the hot water tank The following specific matters are provided for a hot water storage hot water supply system that is configured by a common lower piping portion extending from the lower portion of the hot water storage tank and connected to each other. That is, when the freeze prevention operation is performed in a state where the heating operation by the heating circulation circuit is stopped, while the auxiliary heat source device is operated, the circulation operation by the heat utilization circulation circuit is performed, while the heating circulation circuit Circulation operation is performed, and in the lower piping section, the flow rate is set so that the entire amount of the circulating hot water returned from the heat-use circulation circuit is introduced as the circulating hot water to the heating circulation circuit (Claim 1). .

  In the case of the present invention, hot water heated by the auxiliary heat source device is returned through the heat utilization circulation circuit, and the entire amount of the heated hot water is introduced into the heating circulation circuit connected in communication with the lower piping section. Become. That is, as the circulating hot water to be circulated and supplied for the freeze prevention operation of the heating circulation circuit, the entire amount of the heated hot water returned through the heat utilization circulation circuit can be introduced into the heating circulation circuit and circulated. As a result, it is possible to reliably avoid the occurrence of a situation in which hot water heated by the auxiliary heat source device once flows into the lower part of the hot water tank, so that the temperature stratification in the hot water tank is not disturbed. It becomes possible to maintain stratification. And since temperature stratification is maintained, hot water can be used for hot water supply if it is discharged from the upper part of the hot water tank, while it can be used as an external heat source device if it is taken out from the lower part of the hot water tank for heating operation. On the other hand, an effect based on temperature stratification that it is possible to efficiently perform a heating operation by supplying low-temperature hot water is ensured. In addition, such an action can be communicated by using the lower end portion of the heat circulation circuit and the upstream end portion of the heating circulation circuit in common by the lower piping section without requiring addition of new equipment. This is realized by an easy structure in which the circulation flow rate is set so that the total amount of the circulating hot water returned from the heat utilization circulation circuit is introduced as the circulating hot water for the heating circulation circuit.

  In the hot water storage hot water system of the present invention, when the freeze prevention operation is executed, the circulation flow rate of the circulating hot water returned from the heating circulation circuit to the upper part of the hot water storage tank is taken out from the upper part of the hot water storage tank to the heat utilization circulation circuit. The flow rate can be set to be as described above (claim 2). In this way, the entire amount of heated hot water returned through the heat utilization circuit can be reliably introduced into the heating circuit and circulated. This makes it possible to more reliably avoid the occurrence of a situation in which hot water heated by the auxiliary heat source device once flows into the lower part of the hot water tank, and to reliably maintain temperature stratification in the hot water tank. Is possible.

  As described above, according to the hot water storage hot water supply system according to the present invention, as the circulating hot water to be circulated and supplied for the freeze prevention operation of the heating circulation circuit, the total amount of the heated hot water returned through the heat utilization circulation circuit, It can be circulated by flowing into the heating circuit side, thereby reliably avoiding the occurrence of a situation where hot water heated by the auxiliary heat source device once flows into the lower part of the hot water tank. For this reason, it becomes possible to maintain the temperature stratification without destroying the temperature stratification in the hot water tank. And by maintaining the temperature stratification, hot water can be used for hot water supply if it is discharged from the upper part of the hot water storage tank, while it can be used for hot water supply to the external heat source device if it is taken out from the lower part of the hot water storage tank for heating operation. The effect based on the temperature stratification that the low temperature hot water is supplied and the heating operation can be efficiently performed can be surely obtained. In addition, such effects can be communicated by using the lower end portion of the heat circulation circuit and the upstream end portion of the heating circulation circuit in common by the lower piping section without requiring addition of new equipment. And a simple configuration in which the flow rate is set so that the entire amount of the circulating hot water returned from the heat utilization circuit is introduced as the circulating hot water for the heating circuit.

  In particular, according to the hot water storage hot water system of claim 2, when the freeze prevention operation is executed, the circulation flow rate of the circulating hot water returned from the heating circulation circuit to the upper part of the hot water storage tank is changed from the upper part of the hot water storage tank to the heat utilization circulation circuit. By setting the flow rate so as to be equal to or higher than the take-out flow rate to be taken out, the entire amount of heated hot water returned through the heat utilization circulation circuit can be reliably introduced into the heating circulation circuit side and circulated. Accordingly, it is possible to more reliably avoid the occurrence of a situation in which hot water heated by the auxiliary heat source device once flows into the lower part of the hot water tank, and the temperature stratification in the hot water tank can be reliably maintained.

It is a schematic diagram of the hot water storage hot-water supply system which concerns on embodiment of this invention. FIG. 2 is a diagram corresponding to FIG. 1, in which a hot water flow in the first stage of the freeze prevention operation is represented by a thick line. FIG. 2 is a diagram corresponding to FIG. 1, in which a hot water flow in a second stage of the freeze prevention operation is represented by a thick line. It is a schematic diagram of the hot water storage hot-water supply system contrasted with this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a hot water storage hot water system according to an embodiment of the present invention. In the figure, reference numeral 2 is an external heat source device, 3 is a hot water storage tank, 4 is a water supply circuit for supplying tap water or the like to the hot water storage tank 3 from the outside, and 5 is hot water or an auxiliary heat source taken out from the upper part of the hot water tank 3 A hot water supply circuit for discharging hot water for hot water supply to the hot water tap 7 etc. using hot water after auxiliary heating in the device 6, 8 is hot water after auxiliary heating in the auxiliary heat source device 6 or hot water taken out from the upper part of the hot water storage tank 3 as a heat source A heat utilization circulation circuit that circulates and supplies the heat to the external heat load, 9 is a heating circulation circuit that heats the hot water in the hot water tank 3 by collecting the exhaust heat from the external heat source device 2, and 10 is a heat utilization circulation. A bypass circulation circuit for supplying hot water returned by the circuit 8 to the auxiliary heat source device 6 without entering the hot water storage tank 3 and circulating between the auxiliary heat source device 6 and the external heat load, 11 is the hot water storage hot water system Controller that controls operation That. Here, reference numeral 12 denotes one lower piping part extending outward from the lower outlet 31 of the hot water tank 3, and the upstream end of the heating circuit 9 extending from the lower outlet 31 of the hot water tank 3 by the lower piping part 12. The part and the downstream end part of the heat utilization circuit 8 that returns to the lower outlet 31 of the hot water tank 3 are configured as a common flow path and connected to each other. That is, the return path 86 of the heat utilization circuit 8 and the outlet path 91 of the heating circuit 9 are joined and connected at the junction 13, and the lower piping section 12 from the junction 13 to the lower outlet 31 is the return path. 86 and part of the lead-out path 91.

  In the present embodiment, the external heat source device 2 is for heat exchange heating of hot water in the hot water tank 3 by using exhaust heat generated by the power generation operation of a fuel cell (eg, SOFC; solid oxide fuel cell) 21 as a heat source. is there. While the exhaust heat generated from the fuel cell 21 is supplied to the heat source side of the heat exchanger 22 for exhaust heat recovery, the hot water in the hot water tank 3 supplied by the heating circuit 9 is heated on the heated side of the heat exchanger 22. To be supplied.

  That is, the heating circulation circuit 9 has an upstream end connected to the lower outlet 31 of the hot water storage tank 3 via the lower piping portion 12 and a downstream end connected to the heated side inlet of the heat exchanger 22 for exhaust heat recovery. A lead-out path 91, an introduction path 92 having an upstream end connected to the heated side outlet of the heat exchanger 22 and a downstream end connected to the upper part of the hot water storage tank 3, and a circulation pump 93 are provided. Then, when a heating operation by a heating operation control unit (described later) of the controller 11 is started, the circulation pump 93 is activated, whereby hot water taken out from the lower part of the hot water tank 3 through the outlet path 91 is used for exhaust heat recovery. In the heat exchanger 22, heat exchange heating is performed by exhaust heat from the fuel cell 21, and the hot water after the heat exchange heating is returned to the upper part of the hot water tank 3 through the introduction path 92 to form a temperature stratification in the hot water tank 3. It will be stored heat. The circulation pump 93 is constituted by a DC pump so that the circulation flow rate can be made variable.

  A three-way switching valve 94 is interposed in the middle of the introduction path 92, and a bypass path 95 branched from the middle position of the outlet path 91 to bypass the hot water tank 3 is connected to the three-way switching valve 94. ing. An inlet temperature sensor 96 is interposed in the outlet path 91 on the inlet side of the heat exchanger 22 for exhaust heat recovery, and an outlet temperature sensor 97 is interposed in the inlet path 92 on the outlet side of the heat exchanger 22 for exhaust heat recovery. Has been.

  The hot water storage tank 3 is configured in a sealed manner, and hot water storage temperature sensors 32 and 33 for detecting the internal hot water storage temperature are installed at predetermined upper and lower positions of the hot water storage tank 3.

  In the water supply circuit 4, the upstream end of the main water supply channel 41 is connected to an external water pipe or the like, and the downstream end is connected so as to join the downstream end portion of the heat utilization circuit 8 and the lower pipe portion 12. From the main water supply channel 41, when hot water in the hot water storage tank 3 is consumed, the consumed water is supplied to the hot water storage tank 3 based on the supply water pressure.

  The hot water supply circuit 5 has two types of hot water: hot water via the auxiliary heating hot water discharge path 60 discharged from the upstream end 52 of the main hot water supply path 51 or hot water via the upper connection path 53 drawn directly from the upper part of the hot water tank 3. Any one of these is supplied to the hot water tap 7. That is, the auxiliary heating hot water outlet 60 has an upstream end connected to the upper part of the hot water storage tank 3, and a downstream end having a three-way switching valve 61 with a flow rate adjusting function, a circulation pump 62, a flow rate sensor 63, an inlet side temperature sensor 64, It is connected to the upstream end 52 via the auxiliary heat source device 6, the outlet temperature sensor 65 and the flow rate adjusting valve 66, and the hot water heated and exchanged by the combustion operation of the auxiliary heat source device 6 is supplied to the upstream end 52. Hot water is available. The three-way switching valve 61 is connected to the downstream side of the bypass circulation circuit 10, and the three-way switching valve 61 is controlled by the controller 11 so that the auxiliary heating water outlet 60 is used as hot water supplied to the auxiliary heat source device 6. The function of switching between flowing hot water and hot water passing through the bypass circulation circuit 10 or both, and adjusting the passing flow rate thereof are achieved. In addition, although illustration is abbreviate | omitted in the downstream of the tap water circuit 5, the branch path from the water supply circuit 4 is connected, temperature adjustment by mixed water is possible, and the branch path for pouring the hot water to the bathtub 85 Is also connected.

  Further, a heat source supply path 81 of the heat utilization circulation circuit 8 branches from the auxiliary heating hot water discharge path 60 between the auxiliary heat source device 6 and the flow rate adjusting valve 66, and the heat pump supply path 81 is operated by the operation of the circulation pump 62. Hot and cold water can be supplied as a heat source to the liquid-liquid heat exchangers 82 and 83 for heating an external heat load. Examples of the external heat load (heat utilization target) include a heating medium serving as a heat source of the hot water heating device 84 and a bath water for reheating the bath 85 as shown in the figure. After liquid-liquid heat exchange heating by the liquid heat exchangers 82 and 83, the hot water whose temperature has been lowered by the heat exchange heating is joined to the lower pipe portion 12 through the return path 86 and returned to the lower portion of the hot water tank 3. The downstream side of the return path 86 is also connected to the upstream end of the bypass circulation circuit 10 so as to be able to join, and the hot water returned from the return path 86 is directly supplied to the auxiliary heat source device 6 for reheating. Can be circulated. Thus, the bypass circulation circuit 10 has an upstream end connected to the downstream side of the return path 86 of the heat utilization circulation circuit 8 and a downstream end connected to the three-way switching valve 61 bypassing the hot water tank 3. Can be supplied to the auxiliary heat source device 6 by the switching control.

  The above hot water storage and hot water supply system is controlled by the controller (operation control means) 11 in response to the output of the input setting signal and operation signal from the remote controller 111 and the output of detection signals from various temperature sensors and the like. It has become. The controller 11 includes a heating operation control unit, a hot water supply operation control unit, a heat utilization operation control unit, a freeze prevention operation control unit, and the like for such operation control.

  Hereinafter, the freeze prevention operation by the freeze prevention operation control unit, which is a characteristic control part of the present embodiment, will be described. First, as a premise, the operation of the external heat source device 2 is stopped due to periodic inspection or the like, or the hot water storage tank 3 is in a fully stored state (stores hot water at a predetermined temperature (for example, 65 ° C.) or higher from the upper part to the lower part). The condition that the heating operation by exhaust heat recovery is no longer possible and the heating operation is stopped is established, and a predetermined temperature condition for preventing freezing is established. Thus, the freeze prevention operation is started. As the predetermined temperature condition, the external temperature has dropped below a temperature set as a risk of freezing, or the hot / cold water temperature in the heating circuit 9 (inlet temperature sensor 96 and outlet temperature sensor 97). There is a condition that the temperature of hot water detected by (2) has dropped below the set temperature because there is a concern of freezing. The freeze prevention operation may be started based on a warning signal from the controller on the external heat source device 2 side.

  As the freeze prevention operation, first, as a first stage, hot water taken out from the lower part of the hot water tank 3 by operating the circulation pump 93 of the heating circulation circuit 9 is supplied to the hot water tank through the outlet path 91, the heat exchanger 22 and the inlet path 92. Cycle operation to return to the top. If the detected temperatures of the inlet temperature sensor 96 and the outlet temperature sensor 97 do not rise higher than the set temperature even after the predetermined time has elapsed, the auxiliary heat source device is then operated while continuing the circulation operation in the heating circulation circuit 9. The hot water heated by 6 is circulated and supplied.

  In order to circulate and supply hot water heated by the auxiliary heat source device 6 to the heating circuit 9, the following processing is performed. That is, first, the three-way switching valve 61 is switched and controlled so that the bypass circulation circuit 10 and the auxiliary heat source device 6 communicate with each other, the on-off valve for the liquid-liquid heat exchanger 82 is opened and switched, and the circulation pump 62 Is operated to burn the auxiliary heat source device 6 to preheat the circulating hot water. As a result, the hot water in the circulation path passing through the heat source supply path 81, the liquid-liquid heat exchanger 82, and the return path 86 of the bypass circulation circuit 10, the auxiliary heat source device 6, and the heat utilization circulation circuit 8, as shown by the thick line in FIG. 2. Circulates while being heated by the auxiliary heat source device 6. If the preheating of the entire hot water in the circulation path is completed, then, as a second stage, the flow path in the three-way switching valve 61 communicating with the auxiliary heating hot water discharge path 60 is gradually opened to a predetermined opening, and the hot water storage tank A predetermined flow rate is taken out from the upper part of 3 and supplied to the auxiliary heat source device 6, and hot water after full-scale heating is circulated and supplied to the heating circuit 9. At this time, the circulation flow rate Qj in the heating circulation circuit 9 is controlled to be equal to or higher than the flow rate Qt taken out from the upper part of the hot water tank 3. In this flow control, the heating circulation circuit 9 side changes and sets the discharge flow rate of the circulation pump 93 to a predetermined value, while the heat utilization circulation circuit 8 side uses a flow rate adjusting function of the three-way switching valve 61 to set a predetermined value. Should be set. The circulation pump 62 is constituted by a DC pump so that the discharge flow rate can be made variable, and the circulation pump 62 is changed and set so that the discharge flow rate becomes a predetermined one without using the flow rate adjusting function by the three-way switching valve 61. Also good.

  As described above, the circulation flow rate Qj in the heating circulation circuit 9 is controlled so as to be equal to or higher than the extraction flow rate Qt from the upper part of the hot water tank 3, so that it is taken out from the upper part of the hot water tank 3 and heated by the auxiliary heat source device 6. The flow of hot water (hereinafter referred to as “heated hot water”) is as shown by a thick line in FIG. That is, the heated hot water that has passed through the heat source supply path 81, the liquid-liquid heat exchanger 82, and the return path 86 flows into the outlet 91 of the heating circuit 9 at the junction 13 and the entire amount (total flow rate) flows into the hot water storage tank. 3 does not flow to the lower outlet 31 side. That is, the situation where heated hot water flows into the lower part of the hot water tank 3 can be avoided.

  When heated hot water flows into the outlet 91 of the heating circuit 9 from the junction 13, hot water corresponding to the difference (Qj−Qt) between the circulation flow rate Qj and the extraction flow rate Qt is taken into the lower portion of the hot water storage tank 3. It flows out from the outlet 31 to the lower piping part 12 and the outlet path 91. And it is returned to the upper part of the hot water tank 3 through the outlet path 91, the heat exchanger 22 and the inlet path 92 of the heating circuit 9 while being mixed with the heated hot water.

  In the case of the above embodiment, as the circulating hot water to be circulated and supplied for the freeze prevention operation of the heating circulation circuit 9, the entire amount of the heated hot water supplied through the heat utilization circulation circuit 8 is transferred from the junction 13 to the heating circulation circuit 9 side. As a result, it is possible to reliably avoid the occurrence of a situation in which heated hot water once flows into the lower part of the hot water tank as in the example of FIG. For this reason, temperature stratification can be maintained without destroying the temperature stratification in the hot water tank 3. And since temperature stratification is maintained, hot water can be used if the hot water is discharged from the upper part of the hot water tank 3 for hot water supply, while external heat source can be used if it is taken out from the lower part of the hot water tank 3 for heating operation. The effect | action and effect that exhaust heat recovery is attained efficiently by supplying a low temperature hot water with respect to the heat exchanger 22 of the apparatus 2 can be acquired reliably. Moreover, such actions and effects can be achieved by connecting the downstream end portion of the heat utilization circulation circuit 8 and the upstream end portion of the heating circulation circuit 9 by the lower piping portion 12 without requiring addition of new devices. The flow rate control for making the relation between the circulation flow rate of the heating circulation circuit 9 and the extraction flow rate from the upper part of the hot water storage tank 3 to a predetermined setting, which is made common and can be branched and communicated in three directions at the junction 13. This can be realized with an easy configuration.

<Other embodiments>
In addition, this invention is not limited to the said embodiment, Other various embodiment is included. That is, in the above embodiment, the case where the external heat source device 2 is configured by the fuel cell 21 that uses exhaust heat as a heat source and collects the exhaust heat is shown. Refrigerant exhaust heat) or gas engine (engine coolant exhaust heat), or solar panels that collect solar heat using natural energy as a heat source, or multiple types The present invention can be applied to a hot water storage and hot water supply system that configures an external heat source device in combination and stores heat as hot water storage in the hot water storage tank 3 by these external heat source devices. Further, instead of the auxiliary heat source device 6, an electric heater may be used as the auxiliary heat source device.

  In the said embodiment, although the heating hot water used for freezing prevention operation showed the example which passes the liquid-liquid heat exchanger 82 for heating of the heat utilization circulation circuit 8, it is not restricted to this. It may be passed through the liquid heat exchanger 83, and a path for supplying a heat source to another external heat load (not shown) may be used.

2 External heat source device 3 Hot water storage tank 5 Hot water supply circuit 6 Auxiliary heat source device 8 Heat utilization circulation circuit 9 Heating circulation circuit 11 Controller 12 Lower piping part 61 Three-way switching valve 62 with flow rate adjustment function Circulation pumps 82, 83 Liquid-liquid heat exchanger ( Heat exchanger)
93 Circulation pump

Claims (2)

A heating circulation circuit that heats hot water taken out from the lower part of the hot water tank by an external heat source device and returns it to the upper part of the hot water tank, and hot water discharged from the upper part of the hot water tank to the hot water tap provided outside A heat utilization circuit that branches from the hot water supply circuit and returns to the lower part of the hot water storage tank. The heat utilization circulation circuit includes an auxiliary heat source device and a heat exchanger for heating the heat utilization object. A common lower pipe that extends from the lower part of the hot water storage tank and has an upstream end part extending from the lower part of the hot water storage tank and a downstream end part of the heat utilization circulation circuit returning to the lower part of the hot water storage tank. In the hot water storage hot water system that is configured by the unit and connected to each other,
When the freeze prevention operation is performed in a state where the heating operation by the heating circulation circuit is stopped, the circulation operation by the heat utilization circulation circuit is performed while the auxiliary heat source device is operated, while the circulation operation of the heating circulation circuit is performed And the flow rate is set so that the entire amount of circulating hot water returned from the heat utilization circuit is introduced as circulating hot water to the heating circuit in the lower pipe.
A hot water storage hot water system characterized by that. The hot water storage and hot water supply system according to claim 1,
When the freeze prevention operation is performed, the circulating flow rate of the circulating hot water returned from the heating circulation circuit to the upper part of the hot water storage tank is equal to or higher than the extraction flow rate taken out from the upper part of the hot water storage tank to the heat utilization circulation circuit. A hot water storage hot water system that is set up like this.

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