JP2004125306A - Hot water storage type water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot water storage type water heater capable of preventing tepid water from being formed at the lower part of a hot water storage tank and a heating efficiency from lowering when water is boiled. <P>SOLUTION: This hot water storage type water heater comprises a hot water storage tank 2 supplied to the lower part thereof and delivered from the upper part thereof, a heating means 14 heating stored hot water in the hot water storage tank 2, a tank circulation circuit 7 returning the stored hot water taken out from the upper part of the hot water storage tank 2 to the hot water storage tank 2, a heat exchanger 9 performing heat exchange between the stored hot water circulating in the tank circulation circuit 7 and an external heat load 8, and temperature detection means 18b and 18d detecting the outlet temperature of the heat exchanger 9. A circulation flow rate regulating means 11 regulating circulation flow rate is installed in the tank circulation circuit 7 to regulate the circulation flow rate in the tank circulation circuit 7 so as to vary the temperature of the stored hot water returned to the hot water storage tank 2. The temperature is lowered less than a specified temperature, and a position where the stored hot water is returned to the hot water storage tank 2 is located under the hot water storage tank. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a hot water supply type hot water supply device that exchanges heat between hot water and an external heat load outside a hot water storage tank.
[0002]
[Prior art]
In a conventional hot water storage type water heater with a bathtub reheating function, at the time of reheating of the bathtub, a circulation pump is operated to take out high-temperature water from the upper part of the hot water storage tank into the circulation circuit, and the bath water is exchanged with a bath heat exchanger. Heat exchange is performed, and the medium-temperature water whose temperature has become low is returned to the lower part of the hot water storage tank, thereby reheating the bathtub water (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP 2001-108292 A (Page 4, FIG. 1)
[0004]
[Problems to be solved by the invention]
However, in the above-described conventional configuration, the flow rate of the high-temperature water flowing through the circulation circuit is not adjusted, and the circulation flow rate is uniquely determined by the circulation capacity and the pipe resistance of the circulation pump. For this reason, although the reheating capability of the bathtub water can be increased, the temperature of the hot water returning to the bathtub after passing through the bath heat exchanger cannot be controlled. As a result, the return temperature from the tank circulation circuit to the hot water storage tank increases, and hot water is supplied by a faucet or the like and mixed with the water supplied to the lower part of the hot water storage tank, so that half-way lukewarm water is formed at the lower part of the hot water storage tank, Despite the high return temperature from the circulation circuit, there is a problem that it cannot be used as hot water.
[0005]
Also, using an outdoor unit using a heat pump cycle instead of a heating element as heating means, take out water from the lower part of the hot water storage tank, make hot water with the outdoor unit, and sequentially boil the hot water to the upper part of the hot water storage tank. In the case of a heat pump water heater that heats up as it is stored, if the temperature of the hot water returned from the bath heat exchanger to the hot water storage tank is high, the heating efficiency (coefficient of performance) at the time of heat pump boiling decreases. There is. In addition, the heating efficiency mentioned here means the value obtained by dividing the boiling capacity by the power consumption.
[0006]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and prevents the formation of lukewarm water at the lower part of a hot water storage tank, and, in a heating method using a heat pump cycle, a heating efficiency at the time of boiling (results). It is an object of the present invention to provide a hot water supply type water heater that can prevent a decrease in coefficient.
[0007]
[Means for Solving the Problems]
The present invention provides a hot water storage tank that is supplied with water from a lower part and discharges water from an upper part, a heating unit that heats the hot water stored in the hot water storage tank, a tank circulation circuit that returns hot water stored in the hot water storage tank to the hot water storage tank, and tank circulation. A hot-water storage type water heater comprising a heat exchanger for performing heat exchange between hot-water storage water circulating in a circuit and an external heat load, and temperature detecting means for detecting an outlet temperature of the heat exchanger. The circuit is provided with a circulating flow rate adjusting means for adjusting the circulating flow rate, the circulating flow rate of the tank circulating circuit is adjusted to make the temperature of the hot water returned to the hot water storage tank variable, the temperature is lowered below a predetermined temperature, and the hot water is stored in the hot water storage tank. The position to return to is below the hot water storage tank.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
[Embodiment 1]
FIG. 1 is a configuration diagram of a heat pump water heater according to Embodiment 1 of the present invention, and FIG. 2 is a configuration diagram of a heat pump main body. In FIG. 1, a hot water storage tank 2 is provided in a hot water supply main body 1, a water supply pipe 3 is connected to a lower portion of the hot water storage tank 2, and a pressure reducing valve 4 is provided in the water supply pipe 3. The hot water supply pipe 5 is connected to the upper part, and the hot water supply pipe 5 is provided with a relief valve 6. A tank circulation circuit 7 is connected to upper and lower portions of the hot water storage tank 2, and the tank circulation circuit 7 exchanges heat between hot water stored in the hot water storage tank 2 and hot water in a bathtub 8 which is an external heat load. The heat exchanger 9 includes a circulating pump 10 for circulating the hot water in the hot water storage tank 2 through the tank circulating circuit 7, and a circulating flow regulating valve 11 for adjusting the circulating flow rate of the hot water passing through the tank circulating circuit 7. .
The bathtub 8 is connected to a bathtub water circulation circuit 12 which is a secondary side of the bath heat exchanger 9, and the bathtub water circulation circuit 12 is provided with a circulation pump 13 for circulating bathtub water. A heating circulation circuit 15 is connected to the heat pump main body 14 (described later). The heating circuit 15 is connected to upper and lower portions of the hot water storage tank 2, and the heating circulation circuit 15 is provided with a circulation pump 16.
[0009]
The remaining hot water temperature in hot water storage tank 2 is detected by temperature sensors 17a and 17b. Also, the inlet temperature of the stored hot water to the bath heat exchanger 9 is detected by the stored hot water inlet temperature sensor 18a, and the outlet temperature of the stored hot water from the bath heat exchanger 9 is detected by the stored hot water outlet temperature sensor 18b. The bathtub water inlet temperature to the bath heat exchanger 9 is detected by a bathtub water inlet temperature sensor 18c, and the bathtub water outlet temperature of the bath heat exchanger 9 is detected by a bathtub water outlet temperature sensor 18d. Furthermore, in order to stop the heating operation of the heat pump main body 14, the temperature sensor 19 detects the incoming water temperature.
Then, the control unit 20 reads the detected values of the temperature sensors 17, 17a, 17b, 18a to 18d, and controls the circulating pumps 10, 13, 16 and the circulating flow regulating valve 11 based on the setting of the operation unit 21. Control.
Here, the circulation flow rate regulating valve 11 is throttled to reduce the circulation amount of the hot water in the tank circulation circuit 7 so that the return temperature to the hot water storage tank 2 is equal to or lower than a predetermined temperature (for example, 60 ° C.), and is returned to below the hot water storage tank 2. .
[0010]
In FIG. 2, a heat pump main body 14 includes a compressor 22, a hot water storage heat exchanger 23 for exchanging heat between hot water and high-pressure gas refrigerant discharged from the compressor 22, an expansion valve 24, an outdoor heat exchanger 25, and an accumulator. 26, a fan 27 attached to the outdoor heat exchanger 25 for absorbing heat, and a heating circulation circuit 15 connecting the upper and lower portions of the hot water storage tank 2 and the heat pump body 14. Then, the outlet temperature of the hot-water storage heat exchanger 23 is detected by the boiling temperature sensor 28.
[0011]
Next, the operation of the hot water supply type water heater in the first embodiment will be described. First, the water supplied from the water supply pipe 3 is reduced to a predetermined pressure by the pressure reducing valve 4 and supplied to the hot water storage tank 2. Here, hot water storage tank 2 is always full. The water in the hot water storage tank 2 is taken out from the lower part of the hot water storage tank 2 to the heating circulation circuit 15 by the operation of the circulation pump 16, guided to the hot water storage heat exchanger 23 of the heat pump main body 14, and heat generated by the hot water storage heat exchanger 23. The hot water is exchanged, heated and returned to the upper part of the hot water storage tank 2. Then, the flow rate flowing through the heating circulation circuit 15 is adjusted by the circulation pump 16 so that the temperature of the boiling temperature sensor 28 becomes a temperature (for example, 90 ° C.) set by the operation unit 21. Thereby, 90 ° C. hot water is stored little by little from the upper part of the hot water storage tank 2.
[0012]
When the temperature of the temperature sensor 19 becomes equal to or higher than a certain temperature (for example, 60 ° C.), the boiling by the heat pump method is determined to have been completed because the entire hot water storage tank 2 has been boiled.
At this time, when the temperature of the water entering the heat exchanger 23 for hot water storage is high, the heating efficiency of the heating is high when the temperature of the water entering the heat exchanger 23 for hot water storage is low, but the temperature of the water entering the heat exchanger 23 for hot water supply is high. Has the characteristic that the heating efficiency of boiling decreases.
The expansion water in the hot water storage tank 2 at the time of boiling is discharged from the relief valve 6.
[0013]
When hot water is supplied to a general faucet or the like, the faucet is opened, hot water is supplied through a hot water supply pipe 5 by a water source water pressure, and water is supplied to a lower portion of the hot water storage tank 2.
[0014]
Next, the reheating operation of the bathtub water will be described. When the control unit 20 receives an instruction to start the additional heating of the bathtub 8 by the operation unit 21, the additional heating operation is started. When the additional heating operation is started, first, the circulation pump 13 is operated, and the hot water in the bathtub 8 is guided to the bathtub circulation circuit 12, and is returned into the bathtub 8 through the bath heat exchanger 9. On the other hand, the circulation pump 10 is also operated, and the hot water stored in the hot water is guided from the upper part of the hot water storage tank 2 to the tank circulation circuit 7 and returned to the lower part of the hot water storage tank 2 through the bath heat exchanger 9. At this time, the bath heat exchanger 9 performs heat exchange (heat transfer) from high-temperature hot water stored in the hot-water storage tank 2 to low-temperature bath water, thereby heating the bath water to a temperature suitable for bathing. Let warm.
[0015]
In the vicinity of the bath heat exchanger 9, there are provided a hot water inlet temperature sensor 18a, a hot water outlet temperature sensor 18b, a bath water inlet temperature sensor 18c, and a bath water outlet temperature sensor 18d, and these temperature sensors 18a to 18d are provided. At 18d, the temperature of each part is detected, and the recirculation flow control valve 11 is adjusted based on the detected temperature to perform additional heating control.
[0016]
Next, the control operation of the additional heating of the bathtub 8 will be described in detail. Here, for the following description, the input value which is the detected temperature of the hot water inlet temperature sensor 18a of the bath heat exchanger 9 is Thi, the input value which is the detected temperature of the hot water outlet temperature sensor 18b is Th, and the bath water is used. The input value that is the detected temperature of the inlet temperature sensor 18c is defined as Tci, and the input value that is the detected temperature of the bathtub water outlet temperature sensor 18d is defined as Tco.
[0017]
When bath tub reheating is started by operating the operation unit 21, the circulation flow rate regulating valve 11 is adjusted to reduce the circulation amount of the tank circulation circuit 7, and the return temperature to the hot water storage tank 2, that is, the hot water outlet temperature. The reheating is performed by controlling the input value Tho of the sensor 18b to a predetermined temperature (for example, 60 ° C.) or lower.
It is checked whether or not the input value Tci of the bath water inlet temperature sensor 18c of the bath heat exchanger 9 is equal to or higher than the preset temperature of the bath 8 set by the operation unit 21 or the like. If Tci is equal to or higher than the set temperature, the circulation pump 10 and the circulation pump 13 are turned off, and the reheating of the bathtub 8 is completed.
If Tci is lower than the set temperature, the reheating is continued.
[0018]
Here, since the circulation flow rate regulating valve 11 is adjusted to restrict the flow rate of the tank circulation circuit 7, the reheating heating capacity is limited, Tco can be suppressed to a certain temperature or less, and high-temperature water is supplied to the bathtub 8. It is not supplied and does not cause discomfort. In addition, it is possible to keep Th low and prevent the water temperature in the lower part of the hot water storage tank 2 from becoming high, thereby lowering the heating capacity of the additional heating, but prevent the water temperature in the lower part of the hot water storage tank 2 from rising and prevent the water from being heated by the heat pump method. It is possible to reduce a decrease in heating efficiency at the time of raising.
[0019]
By the way, the same operation is performed when the circulation flow control valve 11 is fully opened, the circulation pump 10 and the circulation pump 13 are turned on, and the bath 8 is additionally heated, but the circulation flow adjustment valve 11 is fully opened. Therefore, the heating capacity of the additional heating becomes high (that is, the time for raising the hot water in the bathtub 8 to the set temperature becomes short). On the other hand, since the input value Tco of the bathtub water outlet temperature sensor 18d increases and high temperature water is supplied into the bathtub 8 or the input value Tho of the storage water outlet temperature sensor 18b increases, the water temperature at the lower portion of the hot water storage tank 2 decreases. Therefore, the heating efficiency at the time of boiling by the heat pump method is lowered.
[0020]
As described above, according to the first embodiment, since the circulation flow rate regulating valve 11 is adjusted to restrict the flow rate of the tank circulation circuit 7, the additional heating capacity is limited, and Tco is suppressed to a certain temperature or less. Since the temperature Tho can be kept lower than the predetermined temperature, the heating capacity of the additional heating can be improved by preventing the water temperature at the lower part of the hot water storage tank 2 from increasing even when the tank circulation circuit 7 is connected below the hot water storage tank 2. Although lower, it is possible to reduce a decrease in heating efficiency at the time of boiling by the heat pump method.
[0021]
[Embodiment 2]
FIG. 3 is a configuration diagram of a heat pump water heater according to Embodiment 2 of the present invention. In the present invention, the bathtub 8 described in the first embodiment is, for example, an external heat load 30 which is a heating device, the bath heat exchanger 9 is an external heat load heat exchanger 31, and the bathtub water circulation circuit 12 is an external heat load. In the circulation circuit 32, the bathtub water inlet temperature sensor 18c is an external heat load inlet temperature sensor 33c, and the bathtub water outlet temperature sensor 18d is an external heat load outlet temperature sensor 33d. A flow path switching valve 34 is attached to the tank circulation circuit 7. The first return pipe 35 a branches off at the flow path switching valve 34 and is connected below the hot water storage tank 2, and is connected above the hot water storage tank 2. The second return pipe 35b is configured.
[0022]
When the external heat load 30 is a heating device, the temperature at which water is supplied to the external heat load 30, that is, the input value Tci of the external heat load inlet temperature sensor 33c must be higher than that in the case of bathtub water. The amount of circulation is maximum, the return temperature to the hot water storage tank 2 is high, Tho becomes equal to or higher than a predetermined temperature (for example, 60 ° C.), and the tank circulation circuit 7 is controlled by the flow path switching valve 34 through the second return pipe 35b. It is connected above the tank 2 and can be used as hot water even when mixed with the remaining hot water above the hot water storage tank 2. Further, since the hot water is supplied from the faucet or the like and does not mix with the water supplied to the lower portion of the hot water storage tank 2, a decrease in the heating efficiency at the time of boiling by the heat pump method can be prevented.
[0023]
【The invention's effect】
As described above, according to the hot water supply type water heater according to the present invention, the circulation flow rate regulating valve is adjusted to control the return temperature of the tank circulation circuit to the hot water storage tank to be lower than or equal to the predetermined temperature and to return the temperature below the hot water storage tank. In addition, by suppressing a rise in the temperature of water in the lower portion of the hot water storage tank, it is possible to prevent a decrease in the heating efficiency at the time of boiling by the heat pump method.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a heat pump water heater according to Embodiment 1 of the present invention.
FIG. 2 is a configuration diagram of a heat pump main body of FIG.
FIG. 3 is a configuration diagram of a heat pump water heater according to Embodiment 2 of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hot water supply main body, 2 Hot water storage tank, 7 Tank circulation circuit, 8 Bathtub, 9 Bath heat exchanger, 10 Circulation pump, 11 Circulation flow control valve (Circulation flow control means), 12 Bath tub water circulation circuit, 14 Heat pump main unit (Heating Means, 15 heating circulation circuit, 18a-18d temperature sensor, 30 external heat load, 31 heat exchanger for external heat load, 32 external heat load circulation circuit, 33c-33d temperature detection means, 34 flow path switching valve (flow path) Switching means), 35a, 35b return pipe.

Claims (3)

A hot water tank supplied with water from a lower part and discharged from an upper part, a heating means for heating the hot water stored in the hot water storage tank, a tank circulation circuit for returning the hot water taken out from the upper part of the hot water storage tank to the hot water storage tank, and the tank circulation A heat exchanger that performs heat exchange between hot water and an external heat load that circulates in the circuit, and a hot water supply type water heater that includes a temperature detection unit and the like that detects an outlet temperature of the heat exchanger.
The tank circulation circuit is provided with a circulation flow rate adjusting means for adjusting a circulation flow rate, the temperature of the hot water returned to the hot water storage tank is adjusted by adjusting the circulation flow rate of the tank circulation circuit, and the temperature is made lower than a predetermined temperature. A hot-water storage type hot water supply device, wherein a position for returning the hot water to the hot water storage tank is below the hot water storage tank. 2. A hot-water supply type hot-water supply system according to claim 1, wherein a heat pump cycle is used as a heating means, and a predetermined temperature is set to 60 [deg.] C. using a heat pump system in which heated hot water is stored in an upper portion of the hot water storage tank and returned from a lower portion of the hot water storage tank. vessel. A hot water tank supplied with water from a lower part and discharged from an upper part, a heating means for heating the hot water stored in the hot water storage tank, a tank circulation circuit for returning the hot water taken out from the upper part of the hot water storage tank to the hot water storage tank, and the tank circulation A heat exchanger that performs heat exchange between hot water and an external heat load that circulates in the circuit, and a hot water supply type water heater that includes a temperature detection unit and the like that detects an outlet temperature of the heat exchanger.
A plurality of return paths for returning the hot water of the tank circulation circuit to the hot water storage tank are provided, and flow path switching means for switching to any of the return paths is provided, and the flow path switching means is switched according to an external heat load. And hot water storage type water heater.

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