JP5866226B2 - Water heater - Google Patents

Description

  Embodiments of the present invention relate to a hot water supply apparatus that supplies hot water in a hot water storage tank to a bathtub.

  2. Description of the Related Art There is known a hot water supply device that includes a hot water storage tank unit that houses a hot water storage tank and a heat pump unit that heats the hot water in the hot water storage tank, and supplies hot water stored in the hot water storage tank from a hot water storage tank unit to a bathtub in a building. .

  The hot water tank unit and the heat pump unit are installed outdoors, and the piping connecting the two units is also installed outdoors. For this reason, when outside temperature becomes low, the water in piping may freeze.

  As a countermeasure, hot water in the hot water storage tank is circulated through the piping by the operation of the pump, and so-called freeze prevention operation is performed in which the piping is heated by the heat of the circulating water. In this anti-freezing operation, the heat of the circulating water is deprived and the temperature of the circulating water gradually decreases, and in the worst case, the circulating water may freeze. When it falls to a predetermined value, the compressor of the heat pump unit is operated to increase the temperature of the circulating water.

JP 2002-48399 A

  If the compressor is frequently operated to prevent freezing, the power consumption increases, which is not preferable in terms of energy saving.

  An object of an embodiment of the present invention is to provide a hot water supply apparatus that is excellent in energy saving and can prevent freezing of piping without causing an increase in power consumption.

A hot water supply apparatus according to an embodiment of the present invention includes a hot water storage tank, a heat pump refrigeration cycle including a compressor, a refrigerant side channel of a water-refrigerant heat exchanger, a decompressor, and an air heat exchanger, and the hot water storage tank. A pipe for circulating the hot water in the water through the water-side flow path of the water-refrigerant heat exchanger, a first temperature detecting means for detecting the outside air temperature, and a second for detecting the temperature of the hot water in the pipe. A temperature detection means and a control means are provided. When the compressor is not in operation, when the detected temperature of the first temperature detecting means or the detected temperature of the second temperature detecting means is less than the set value, the hot water in the pipe is removed from the water-refrigerant heat exchanger. A first circulation path that circulates in the pipe through the water-side flow path is formed, and the detection temperature of the second temperature detection means does not exceed the set value despite the formation of the first circulation path. A hot water in the hot water storage tank forms a second circulation path that returns to the hot water storage tank through the pipe and the water-side flow path of the water-refrigerant heat exchanger. Further, the control means is configured in a state where the first circulation path is formed for a certain period of time when the detected temperature of the second temperature detection means is not equal to or higher than the set value despite the formation of the second circulation path. Turn on compressor operation.

The figure which shows the structure of 1st Embodiment. The flowchart which shows control of the controller of 1st Embodiment. The figure which shows the 1st circulation path of 1st Embodiment. The figure which shows the 2nd circulation path of 1st Embodiment. The flowchart which shows control of the controller of 2nd Embodiment. The flowchart which shows control of the controller of 3rd Embodiment. The figure which shows the 2nd circulation path of 3rd Embodiment.

[1] A first embodiment will be described below with reference to the drawings.
In FIG. 1, 1 is a hot water supply unit (also referred to as a hot water storage tank unit) installed outdoors, and water is supplied from an external water supply pipe P1. This water is led to the bottom inlet of the hot water storage tank 5 by the pipe 2 and through the pressure reducing valve 3 and the check valve 4 on the pipe 2. A part of the water flowing between the pressure reducing valve 3 and the check valve 4 in the pipe 2 is led to the first inlet of the mixing valve 7 through the check valve 6, and the hot water flowing out from the mixing valve 7 is piped. 8 is supplied to an external hot water supply pipe P2. A flow rate sensor 9 is attached to the pipe 8. The hot water supply pipe P2 is extended to a kitchen, a washroom, a bathroom, and the like. A second inlet of the mixing valve 7 is connected to an upper outlet of the hot water storage tank 5 through a pipe 10.

  A check valve 11 is disposed in the middle of the pipe 10, and hot water upstream of the check valve 11 in the pipe 10 is guided to the first inlet of the mixing valve 12. Water between the pressure reducing valve 3 and the check valve 4 in the pipe 2 is guided to the second inlet of the mixing valve 12. Then, hot water flowing out from the mixing valve 12 is supplied to the outdoor pipe P3 through the pipe 14 and through the hopper 15, the silver ion generator 20, and the flow switch 21 on the pipe 14. The pipe P3 is introduced into the building and connected to the circulation fitting 62 of the bathtub 61 of the bathroom 60. The hopper 15 includes an on-off valve 16, a check valve 17, a flow sensor 18, and a check valve 19. A water temperature sensor (temperature detection means) 22 for detecting the temperature Tr of the internal hot water and a water level sensor 23 are attached to the pipe 14.

  Further, a part of the hot water passed through the silver ion generator 20 of the pipe 14 is supplied to the first flow path of the heat exchanger 26 for heating through the pump (so-called bath pump) 24 and the pipe 25, Hot water passing through the first flow path is supplied to the outdoor pipe P4 through the pipe 27. This pipe P4 is also introduced into the building and connected to the circulation fitting 62 of the bathtub 61. A hot water temperature sensor 28 for detecting the temperature Ti of hot water flowing toward the pipe P4 is attached to the pipe 27.

  Hot water on the upstream side of the check valve 11 in the pipe 10 is led to the second flow path of the heat exchanger 26 by the pipe 30 and via the check valve 31 on the pipe 30, The passed hot water is supplied to the side inlet of the hot water storage tank 5 by a pipe 32 and a pump (so-called additional cooking pump) 33.

  Hot water flowing out from the bottom outlet of the hot water storage tank 5 is supplied to the external pipe P5 by the pipe 40 and the circulation pump 41. This pipe P5 is connected to a water inlet of a heat pump unit 70 that is a heating means. The upstream position of the circulation pump 41 in the pipe 40 is connected to the first outlet of the three-way valve 42, and the inlet of the three-way valve 42 is connected to the external pipe P 6 through the pipe 43. The pipe P6 is connected to the outlet of the heat pump unit 70. The three-way valve 42 causes hot water flowing in from the pipe 43 to flow out from one or both of the first outlet and the second outlet. Hot water flowing out from the second outlet is led to the upper inlet of the hot water storage tank 5 by the pipe 44. An incoming water temperature sensor 45 is attached to the pipe 43, and a boiling temperature sensor 46 is attached to the pipe 44. The incoming water temperature sensor 45 detects the temperature Tt1 of hot water flowing into the hot water supply unit 1 from the pipe P6. The boiling temperature sensor 46 detects the temperature Tt2 of hot water flowing from the pipe 44 to the upper inlet of the hot water storage tank 5.

  The temperature and water level of the hot water in the hot water storage tank 5 are detected by a plurality of temperature sensors T1, T2,... T6 arranged in order from the lower part to the upper part of the hot water storage tank 5.

  The heat pump unit 70 includes a compressor 71, a refrigerant-side flow path of the water-refrigerant heat exchanger 72, a first flow path of the internal heat exchanger 73, a decompressor such as an expansion valve 74, an air heat exchanger 75, and internal heat. It has a heat pump refrigeration cycle in which the second flow path of the exchanger 73 is sequentially connected to circulate the refrigerant, a fan 76 that sends outside air to the air heat exchanger 75, and hot water flowing from the pipe P5 is converted into water-refrigerant heat. A pipe 77 that leads to the water-side flow path of the exchanger 72, a pipe 78 that leads hot water flowing out from the water-side flow path of the water-refrigerant heat exchanger 72 to the pipe P6, and a water supply that detects the temperature Twi of hot water in the pipe 77 A temperature sensor (second temperature detection means) 81 and a boiling temperature sensor (second temperature detection means) 82 for detecting the temperature Two of hot water in the pipe 78 are provided, and hot water supplied from the hot water supply unit 1 is taken from outside air. Pumped heat Heating supplies hot water obtained by the heat to the hot water supply unit 1. Electric heaters 91 and 92 for preventing freezing are mounted on the pipes P5 and P6 between the heat pump unit 70 and the hot water supply unit 1, respectively. By connecting the power plug 93 led out from these electric heaters 91 and 92 to the outlet of a commercial AC power supply, the electric heaters 91 and 92 generate heat and the pipes P5 and P6 are heated.

  In addition, a controller 50 is provided in the hot water supply unit 1, and the controller 50 includes a valve / pump / temperature sensor in the hot water supply unit 1, an outside air temperature sensor (first temperature detecting means) 51, and a remote control type operating device for the bathroom 60 ( (Hereinafter abbreviated as remote control) 63, heat pump unit 70, and electric heaters 91 and 92 are connected.

The controller 50 controls the entire water supply apparatus, and controls the following means (1) to (7) as main functions.
(1) Hot water supply means for supplying hot water in the hot water storage tank 5 to the bathtub 61 through the pipes P3 and P4.

  (2) Thermal insulation and reheating means for circulating hot water in the bathtub 61 to the circulation path passing through the pipes P3 and P4 and the heat exchanger 26 by the operation of the pump 24.

  (3) Hot water storage operation means for heating hot water in the hot water storage tank 5 by the heat pump unit 70 and storing the hot water obtained by this heating in the hot water storage tank 5 in the midnight power time zone.

  (4) When the compressor 71 in the heat pump unit 70 is not in operation, when either the detected temperature To of the outside air temperature sensor 51 or the detected temperature Twi of the temperature sensor 81 is less than the set value, First control means for forming a first circulation path that circulates in the pipes P5 and P6 through the water-side flow path of the water-refrigerant heat exchanger 72.

  (5) When the detected temperature Twi of the temperature sensor 81 is not equal to or higher than the set value in spite of the formation of the first circulation path, the hot water in the hot water storage tank 5 is connected to the pipe until the detected temperature Twi increases by a predetermined value. Second control means for forming a second circulation path that returns to the hot water storage tank 5 through P5 and P6 and the water-side flow path of the water-refrigerant heat exchanger 72, and then returns to the formation of the first circulation path. Specifically, the second circulation path is a closed water path that returns the hot water in the lower part of the hot water storage tank 5 to the upper part of the hot water storage tank 5 through the pipes P5 and P6 and the water-side flow path of the water-refrigerant heat exchanger 72. is there.

  (6) After returning from the formation of the second circulation path to the formation of the first circulation path, when the detected temperature Twi of the temperature sensor 81 is not equal to or higher than the set value, the first circulation path is formed for a certain period of time. The third control means for turning on the operation of the compressor 71 of the heat pump unit 70.

  (7) At the time of forming the first circulation path, the difference (= Tt1−Twi) between the detected temperature Tt1 of the incoming water temperature sensor 45 and the detected temperature Twi of the feed water temperature sensor 81 is detected as a temperature decrease due to heat radiation from the pipe P5. In addition, the difference (= Two−Tt1) between the detected temperature Two of the boiling temperature sensor 82 and the detected temperature Tt1 of the incoming water temperature sensor 45 is detected as a temperature decrease amount due to heat radiation from the pipe P6, and these detected temperature decrease amounts If any of the above is greater than the set amount, it is necessary to operate the electric heaters 91 and 92 for preventing freezing mounted on the pipes P5 and P6, and the power source of the electric heaters 91 and 92 for the operation. Informing means for informing that it is necessary to connect the plug 93 to an outlet by displaying on the display unit of the remote controller 63.

Next, hot water supply, heat insulation and additional cooking performed under the control of the controller 50 will be described.
In the midnight power time zone, the compressor 71 in the heat pump unit 70 is turned on, and the refrigerant discharged from the compressor 71 is the refrigerant-side flow path of the water-refrigerant heat exchanger 72 and the first flow of the internal heat exchanger 73. The air is drawn into the compressor 71 through the second flow path of the passage, the expansion valve 74, the air heat exchanger 75, and the internal heat exchanger 73. Accordingly, the circulation pump 41 of the hot water supply unit 1 is turned on, the first outlet and the inlet of the three-way valve 42 are communicated, and the hot water in the lower part of the hot water storage tank 5 is connected to the pipe 40, the circulation pump 41, the pipe P5, Hot water heated by the water-refrigerant heat exchanger 72 flows through the pipe 78, the pipe P6, the pipe 43, and the three-way valve 42 through the pipe 77 to the water-side flow path of the water-refrigerant heat exchanger 72. Return to 40.

  When the temperature Two of hot water passing through the pipe 78 is detected by the boiling temperature sensor 82 and the detected temperature reaches a predetermined hot water storage temperature, the three-way valve 42 is configured so that the inlet is in communication with the second outlet. Switched. As the three-way valve 42 is switched, hot water heated by the water-refrigerant heat exchanger 72 flows through the pipe 78, the pipe P6, the pipe 43, the three-way valve 42, and the pipe 44 to the upper part of the hot water storage tank 5. As a result, hot water is stored in the hot water storage tank 5.

  When automatic operation and hot water supply are set by the remote controller 63, the open / close valve 16 of the hopper 15 is opened. Thereby, hot water in the hot water storage tank 5 is supplied to the bathtub 61 through the pipe 10, the mixing valve 12, the pipe 14, the hopper 15, the silver ion generator 20, the flow switch 21, and the pipe P3, and the silver ion generator. The hot water having passed through 20 is also supplied to the bathtub 61 through a path passing through the pump 24, the pipe 25, the heat exchanger 26, the pipe 27, and the pipe P4. At this time, the hot water supply amount to the bathtub 61 is detected by the flow sensor 18 in the hopper 15, and when the detected amount reaches the set hot water amount of the remote control 63, the on-off valve 16 of the hopper 15 is closed and the hot water supply is finished. .

  Thereafter, when heat retention or additional cooking is set by the remote controller 63, the pump 24 is turned on, and the hot water in the bathtub 61 is supplied to the pipe P3, the pipe 14, the pump 24, the pipe 25, the first flow path of the heat exchanger 26, It circulates through the piping 27 and the piping P4. At this time, the temperature of hot water passing through the pipe 27 is detected by the hot water temperature sensor 28, and if the detected temperature does not reach the set hot water temperature of the remote controller 63, the pump 33 is turned on. When the pump 33 is turned on, the hot water in the hot water storage tank 5 circulates through the pipes 10 and 30, the second flow path of the heat exchanger 26, the pipe 32 and the pump 33, and passes through the second flow path of the heat exchanger 26. The heat of the hot water passing through heats the hot water in the bathtub circulation passing through the first flow path of the heat exchanger 26. Thus, the hot water in the bathtub 61 is heated. When the temperature detected by the hot water temperature sensor 28 reaches the set hot water temperature, the pumps 24 and 33 are turned off, and the heat insulation or cooking is completed.

On the other hand, when the automatic operation is canceled by the remote controller 63 and when the compressor 71 is not in operation, the controller 50 executes the control shown in the flowchart of FIG.
The detected temperature To of the outside air temperature sensor 51 and the first set value, for example, 3 ° C. are compared (step 101), and the detected temperature Twi of the feed water temperature sensor 81 and the second set value, for example, 3 ° C. are compared (step). 102). When the detected temperature To is less than 3 ° C. (YES in step 101) or when the detected temperature Twi is less than 3 ° C. (YES in step 102), the flag f is set to “0” (step 103), and three-way The first outlet and the inlet of the valve 42 are communicated (step 104). Further, the circulation pump 41 is turned on (step 105).

  When the first outlet and the inlet of the three-way valve 42 are communicated with each other and the circulation pump 41 is turned on, the hot water in the pipe P5 is supplied to the pipe 77 of the heat pump unit 70, as shown by the arrow in FIG. The refrigerant heat exchanger 72 flows to the pipe P6 through the water-side flow path and the pipe 78, and the hot water in the pipe P6 passes through the pipe 43, the three-way valve 42, the pipe 40, and the circulation pump 41 in the hot water supply unit 1. A first circulation path (also referred to as a first closed water path) returning to P5 is formed. The circulation of the hot water prevents the pipes P5 and P6 and the surrounding area from freezing.

  When the circulation pump 41 is turned on, the time count t1 is started (step 106). When the time count t1 reaches a certain time ta (YES in step 107), the detected temperature Twi of the feed water temperature sensor 81 and the third set value are set. (> Second set value) For example, 4 ° C. is compared (step 108). The fixed time ta is a time required for at least the hot water in the pipe P5 to go through the first circulation path.

  If the detected temperature Twi is 4 ° C. or higher (YES in step 108), the circulation pump 41 is turned off (step 109). Thereby, the freeze prevention treatment for the pipes P5 and P6 is completed. Accordingly, the time count t2 is started (step 110), and when the time count t2 reaches a certain time tb (YES in step 110), the process returns to the temperature comparison process in steps 101 and 102. The fixed time tb is a waiting time that is secured for the regular execution of the freeze prevention treatment.

  However, the hot water flowing through the first circulation path gradually loses its temperature due to the heat taken away by the pipes P5 and P6 and other members. If this temperature continues, the water in the pipes P5 and P6 may eventually freeze.

  Therefore, if the detected temperature Twi at the time when the formation of the first circulation path continues for a certain time ta is less than 4 ° C. (NO in step 108), the flag f is “0” (YES in step 112). The current detected temperature Twi is held as Twi1 (step 113), and the three-way valve 42 is switched so that the inflow port communicates with the second outflow port (step 114). The circulation pump 41 continues to be on. In this case, as indicated by arrows in FIG. 4, the hot water in the lower part of the hot water storage tank 5 is drawn into the pipe P5 through the pipe 40 and the circulation pump 41, and the drawn hot water is drawn from the pipe P5 to the pipe 77, water-refrigerant. A second circulation path (also referred to as a second closed water path) that returns to the upper part of the hot water storage tank 5 through the heat exchanger 72, the pipe 78, the pipe P6, the pipe 43, the three-way valve 42, and the pipe 44 is formed. Thus, the warm hot water in the hot water storage tank 5 is taken into the circulating water whose temperature has been lowered, so that the temperature of the circulating water rises uniformly. Thereby, the malfunction which the water in piping P5, P6 freezes can be prevented beforehand.

  Along with the transition to the second circulation path, the detected temperature Twi of the feed water temperature sensor 81 is compared with a predetermined value (= Twi1 + 3 ° C) obtained by adding, for example, 3 ° C to the holding temperature Twi1 (step 115). When the detected temperature Twi rises to a predetermined value due to the transition to the second circulation path (YES in step 115), the flag f is set to “1” under the judgment that the temperature of the circulating water has risen uniformly. (Step 116) Subsequently, returning to the formation of the first circulation path in Steps 104 and 105, the time count t1 is started again (Step 106). When the time count t1 reaches the predetermined time ta (YES in step 107), it is determined whether or not the detected temperature Twi of the feed water temperature sensor 81 has risen to 4 ° C. or more (step 108).

  If detected temperature Twi has risen to 4 ° C. or higher (YES in step 108), circulation pump 41 is turned off (step 109). Thereby, the freeze prevention measures including the transition from the first circulation path to the second circulation path and the return from the second circulation path to the first circulation path are completed. Then, the time count t2 is started (step 110), and when the time count t2 reaches a certain time tb (YES in step 111), the process returns to the temperature comparison process in steps 101 and 102.

  The return from the second circulation path to the first circulation path occurs when the temperature detected by the feed water temperature sensor 81 (temperature of hot water flowing into the heat pump unit 70 from the pipe P5) Twi reaches a predetermined value (= Twi1 + 3 ° C.). is there. That is, hot water drawn from the hot water storage tank 5 during the period in which the second circulation path is formed flows from the pipe 40 to the pipe P5 and almost fills the pipe P5. It does not flow in the water side flow path, the pipe 78, and the pipe P6 of the vessel 72. In this case, the amount of hot water drawn from the hot water storage tank 5 and filling the piping 40 and the piping P5 is the amount of piping and equipment existing on the second circulation path (water-side flow path / circulation pump 41 etc. of the water-refrigerant heat exchanger 72). It corresponds to the amount that fills about half of the total volume of. Therefore, if the circulating water temperature immediately before switching to the second circulation path is 5 ° C. and the temperature of the hot water in the lower part of the hot water storage tank 5 is 50 ° C., the circulating water temperature after the transition to the second circulation path is It is almost “(5 ° C. + 50 ° C.) / 2 = 25.75 ° C.”. This is a temperature sufficient to prevent the pipes P5 and P6 from freezing.

  Although the detected temperature Twi of the feed water temperature sensor 81 is used for switching control between the first circulation path and the second circulation path, the detected temperature Two of the boiling temperature sensor 82 can of course be used for the switching control. . When the detection temperature Two of the boiling temperature sensor 82 is used for the switching control, the hot water drawn from the hot water storage tank 5 through the pipe 40 through the pipe P5 during the period in which the second circulation path is formed further passes through the pipe 77, The water-refrigerant heat exchanger 72 flows into the water-side flow path and the pipe 78. That is, the amount of hot water drawn from the hot water storage tank 5 and flowing to the pipe 78 corresponds to an amount satisfying a volume larger than about half of the total volume of the pipes and equipment existing on the second circulation path.

  By the way, even if the temperature of the circulating water rises uniformly due to the formation of the second circulation path, after returning from the second circulation path to the first circulation path due to a sudden decrease in the outside air temperature To or the occurrence of cold wind and rain, etc. It is conceivable that the detected temperature Twi is less than 4 ° C. (NO in step 108). In this case, since the flag f is “1” (NO in step 112), the compressor 71 is turned on (step 117). With this operation on, the circulating water in the first circulation path is heated by the water-refrigerant heat exchanger 72.

  Simultaneously with this heating, a time count t3 is started (step 118), and when the time count t3 reaches a certain time tc (YES in step 119), the compressor 71 of the heat pump unit 70 is turned off (step 120). Then, the time count t2 is started (step 110), and when the time count t2 reaches a certain time tb (YES in step 111), the process returns to the temperature comparison process in steps 101 and 102.

  As described above, first, the first circulation path is formed to prevent the pipes P5 and P6 and the surrounding pipes from freezing, and the second circulation path when there is a risk of freezing despite the formation of the first circulation path. By taking the warm hot water from the hot water storage tank 5 into the circulating water and shifting to, the power consumption can be greatly reduced compared to the case where the compressor is frequently operated to prevent freezing. Since the first circulation path and the second circulation path are sequentially formed, the number and range of pipes that are subject to freeze prevention can be increased.

  If there is a risk of freezing due to the formation of the second circulation path, the compressor 71 is turned on. Therefore, the pipes P5 and P6 and the surrounding area are connected regardless of the sudden decrease in the outside air temperature To or the occurrence of cold wind and rain. Freezing can be surely prevented.

  When the first circulation path is formed, the difference (= Tt1−Twi) between the detected temperature Tt1 of the incoming water temperature sensor 45 and the detected temperature Twi of the water supply temperature sensor 81 is the amount of temperature decrease due to heat radiation from the pipe P5. While being detected, a difference (= Two−Tt1) between the detected temperature Two of the boiling temperature sensor 82 and the detected temperature Tt1 of the incoming water temperature sensor 45 is detected as a temperature decrease amount due to heat radiation from the pipe P6. If any of these temperature drop amounts is equal to or greater than the set amount, it is necessary to operate the electric heaters 91 and 92 for preventing freezing attached to the pipes P5 and P6, and the electric heater 91, The fact that it is necessary to connect the 92 power plugs 93 to the outlet is informed by the display on the remote controller 63.

  The electric heaters 91 and 92 for preventing freezing are mainly used in winter. Since the power plug 93 is unplugged from the outlet by the user after the winter season, the above notification is performed to prevent the trouble that the electric heaters 91 and 92 are not operated and the pipes P5 and P6 are frozen in the next winter season. Can do.

  In the above embodiment, the first circulation path is formed when the detected temperature To of the outside air temperature sensor 51 is lower than the first set value or the detected temperature Tw1 of the feed water temperature sensor 81 is lower than the second set value. The circulation pump 41 is turned on. However, the present invention is not limited to this, and when both the detected temperature To of the outside air temperature sensor 51 and the detected temperature Tw1 of the feed water temperature sensor 81 are respectively reduced below the set value, the first A circulation path may be formed and the circulation pump 41 may be turned on.

[2] A second embodiment will be described.
Of the control of the means (1) to (7) which are the main functions of the controller 50, the second control means (5) is different from the first embodiment as follows.

  (5) If the detected temperature Twi of the temperature sensor 81 is not equal to or higher than the set value despite the formation of the first circulation path, the second is based on at least the detected temperature Twi and the detected temperature T1x of the temperature sensor T1 in the hot water storage tank 5. The required formation time td of the circulation path is set, and hot water in the hot water storage tank 5 passes through the pipes P5 and P6 and the water side flow path of the water-refrigerant heat exchanger 72 to the hot water storage tank 5 only for the required formation time td. Second control means for forming a return second circulation path and then returning to the formation of the first circulation path. The detection temperature T1x of the temperature sensor T1 is the temperature of the hot water in the lower part of the hot water storage tank 5.

  That is, as shown in the flowchart of FIG. 5, steps 201 to 204 are executed instead of steps 113 to 115 of the first embodiment.

  If the detected temperature Twi of the temperature sensor 81 at the time when the formation of the first circulation path continues for a certain time ta is less than 4 ° C. (NO in step 108), the flag f is “0” (step 112). YES), the required formation time td of the second circulation path is set based on at least the detected temperature Twi at that time and the detected temperature T1x of the temperature sensor T1 in the hot water storage tank 5 (step 201).

Specifically, the required formation time td includes the detection temperature Twi of the temperature sensor 81, the detection temperature T1x of the temperature sensor T1, piping and equipment existing on the second circulation path (the water-side flow path of the water-refrigerant heat exchanger 72, Required amount Wn (L) of the total volume C (L) of the circulation pump 41 and the like, the target temperature Ts of the circulating water, and the required amount Wn (L) of hot water from the hot water storage tank 5 ) Is obtained, and the required pull-in amount Wn (L) is divided by the water supply amount P (L / min) per unit time of the circulation pump 41.
Twi · (C−Wn) + T1x · Wn = C · Ts
td = Wn / P (l / min)
For example, the detected temperature Twi of the temperature sensor 81 is 3 ° C., the detected temperature T1x of the temperature sensor T 1 is 50 ° C., the total volume C of piping and equipment existing on the second circulation path is 4 (L), and the target temperature Ts of circulating water is If the water supply amount P per unit time of the circulation pump 41 is 1 (L / min) at 20 ° C., about 87 seconds is required as the required formation time td.
3 ° C. × [4 (L) −Wn (L)] + 50 ° C. × Wn (L) = 4 (L) × 20 ° C.
Wn (L) ≒ 1.45 (L)
td ≒ 87 seconds
With the setting of the necessary formation time td, the second outlet of the three-way valve 42 is communicated with the inlet (step 202). Thereby, a second circulation path is formed.

  With the transition to the second circulation path, the time count t4 is started (step 203). When the time count t4 reaches the necessary formation time td (YES in step 204), the temperature of the circulating water rises uniformly. If it is determined that the target temperature Ts has been reached, the flag f is set to “1” (step 116), and then the process returns to the formation of the first circulation path in steps 104 and 105.

As described above, by appropriately calculating and setting the time necessary for forming the second circulation path, it is possible to perform an appropriate and efficient freezing prevention measure following changes in the environment.
Other configurations and operations are the same as those in the first embodiment. Therefore, the description is omitted.

[3] A third embodiment will be described.
Of the control of the means (1) to (7) which are the main functions of the controller 50, the second control means (5) is different from the first embodiment as follows.

  (5) If the detected temperature Twi of the temperature sensor 81 is not equal to or higher than the set value despite the formation of the first circulation path, the hot water in the lower portion of the hot water storage tank 5 is connected to the pipe P5 until the detected temperature Twi rises by a predetermined value. The water-refrigerant heat exchanger 72 returns to the upper part of the hot water storage tank 5 through the water-side flow path and the pipe P6, and a part of the hot water passing through the water-side flow path of the water-refrigerant heat exchanger 72 is stored in the hot water storage tank. 2nd control means which forms the 2nd circulation path which joins the flow of hot water from 5 to piping P5, and returns to formation of the 1st circulation path after that.

  That is, as shown in the flowchart of FIG. 6, the process of step 301 is executed instead of the process of step 114 of the first embodiment.

  If the detected temperature Twi of the temperature sensor 81 at the time when the formation of the first circulation path continues for a certain time ta is less than 4 ° C. (NO in step 108), the flag f is “0” (step 112). YES), the current detected temperature Twi is held as Twi1 (step 113), and the first outlet and the second outlet of the three-way valve 42 are both communicated with the inlet (step 301).

  When the first outlet and the second outlet of the three-way valve 42 are both in communication with the inlet, the hot water in the lower part of the hot water storage tank 5 passes through the pipe 40 and the circulation pump 41 as shown in FIG. The drawn hot water is drawn into the hot water tank 5 through the pipe P5 through the pipe 77, the water-side flow path of the water-refrigerant heat exchanger 72, the pipe 78, the pipe P6, the pipe 43, the three-way valve 42, and the pipe 44. Returning to the upper part, a part of the hot water flowing into the pipe 43 from the water side flow path of the water-refrigerant heat exchanger 72, the pipe P6, flows into the hot water flow from the hot water storage tank 5 to the pipe P5 via the three-way valve 42. Join.

  The warm hot water in the hot water storage tank 5 is taken into the circulating water whose temperature has been lowered, so that the temperature of the circulating water rises uniformly. Thereby, the malfunction which the water in piping P5, P6 leads to freezing can be prevented. Further, a part of hot water passing through the water-side flow path of the water-refrigerant heat exchanger 72 and the pipe P6 joins the flow of hot water from the hot water storage tank 5 to the pipe P5, so that the hot water returns to the upper part of the hot water storage tank 5. The amount per unit time is smaller than that in the first embodiment. As a result, since the temperature drop of the hot water in the hot water storage tank 5 is reduced, the amount of hot water taken into the second circulation path can be increased.

  That is, the hot water in the lower part of the hot water storage tank 5 is taken not only from the pipe 40 to the pipe P5 but also into the pipe 77, the water-side flow path of the water-refrigerant heat exchanger 72, the pipe 78, and the pipe P6 with a margin. be able to. By extending this uptake route, the time required for the temperature of the circulating water to rise uniformly can be shortened. This leads to shortening of the operation time of the circulation pump 41, and also in this respect, power consumption can be reduced.

The distribution ratio between the amount of hot water returning to the upper part of the hot water storage tank 5 and the amount of hot water that does not return to the upper part of the hot water storage tank 5 and merges with the flow of hot water from the lower part of the hot water storage tank 5 to the pipe P5 is the same. In contrast, by increasing the merging side, the temperature difference between the hot water that drops in temperature via the pipes P5 and P6 and the hot water that merges with it is reduced. As a result, the time required for the temperature of the circulating water to rise uniformly when returning from the second circulation path to the first circulation path can be shortened. This also leads to shortening of the operation time of the circulation pump 41, which leads to reduction of power consumption.
Other configurations and operations are the same as those in the first embodiment. Therefore, the description is omitted.

  In addition, each said embodiment and modification are shown as an example, and are not intending limiting the range of invention. Each of the novel embodiments and modifications can be implemented in various other forms, and various omissions, rewrites, and changes can be made without departing from the spirit of the invention. In these embodiments and modifications, the scope of the invention is included in the gist, and is included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Hot water supply unit, 5 ... Hot water storage tank, 7, 12 ... Mixing valve, 15 ... Hopper, 20 ... Silver ion generator, 41 ... Pump, 42 ... Three-way valve, 50 ... Controller, 51 ... Outside temperature sensor (1st temperature) Detecting means), 60 ... Bath room, 61 ... Bathtub, 63 ... Remote control, P5, P6 ... Piping, 70 ... Heat pump unit, 71 ... Compressor, 72 ... Water-refrigerant heat exchanger, 75 ... Air heat exchanger, 81 ... Feed water temperature sensor, 82 ... Boiling temperature sensor (second temperature detecting means), 91, 92 ... Electric heater, 93 ... Power plug

Claims (3)

A hot water storage tank for hot water supply,
A heat pump refrigeration cycle including a compressor, a refrigerant-side flow path of a water-refrigerant heat exchanger, a decompressor, and an air heat exchanger;
Piping for circulating hot water in the hot water storage tank through the water side flow path of the water-refrigerant heat exchanger;
First temperature detection means for detecting the outside air temperature;
Second temperature detecting means for detecting the temperature of the hot water in the pipe;
When the compressor is not in operation, when either the detected temperature of the first temperature detecting means or the detected temperature of the second temperature detecting means is less than a set value, the hot water in the pipe is converted into the water-refrigerant heat exchanger. A first circulation path that circulates in the pipe through the water-side flow path, and the temperature detected by the second temperature detection means is not equal to or higher than the set value despite the formation of the first circulation path. Control means for forming a second circulation path for the hot water in the hot water storage tank to return to the hot water storage tank through the pipe and the water-side flow path of the water-refrigerant heat exchanger;
Equipped with a,
When the detected temperature of the second temperature detecting means is not equal to or higher than the set value in spite of the formation of the second circulation path, the control means performs the compression in a state in which the first circulation path is formed for a certain period of time. Turn on the machine,
A water heater characterized by that. The second circulation path returns the hot water in the lower part of the hot water storage tank to the upper part of the hot water storage tank through the pipe and the water-side flow path of the water-refrigerant heat exchanger.
The hot water supply apparatus according to claim 1. The second circulation path returns the hot water in the lower part of the hot water storage tank to the upper part of the hot water storage tank through the pipe and the water-side flow path of the water-refrigerant heat exchanger, and the water-refrigerant heat exchanger. A part of the hot water that has passed through the water-side flow path is joined to the flow of hot water from the hot water storage tank to the pipe,
The hot water supply apparatus according to claim 1.

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