JP2003314897A - Hot water storage type water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent freezing of piping in a hot water storage type water heater, while minimizing increase in the power consumption of the hot water storage type water heater. <P>SOLUTION: When an outside air temperature drops to cause a detection temperature of any of an inlet temperature sensor 28, an outlet temperature sensor 29 and a hot water storage tank inlet temperature sensor 30 to be a first set temperature (5°C), a microcomputer 40 is operated to hold a water intake valve 20 open, open a return valve 26, close a flow regulating valve 24 and operate a circulating pump 19. The operation of the circulating pump 19 circulates low temperature water of a low temperature layer stored in a lower layer 10a in a lower section of a hot water storage tank 10 back to the lower layer 10a in the hot water storage tank 10, through the water intake valve 20, the circulating pump 19, a feed pipe 18, a refrigerant-to-water heat exchanger 2 of a heat pump unit 100, a first return pipe 23, a second return pipe 25 and the return valve 26, to thereby prevent freezing of the feed pipe 18 and the first return pipe 23. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot water storage type water heater such as a heat pump type water heater which utilizes the heat of condensation of a refrigerant. More specifically, the present invention relates to prevention of freezing of water in a pipe of a hot water storage type water heater having a hot water storage tank.

[0002]

2. Description of the Related Art Conventionally, in hot water storage type water heaters such as heat pump type water heaters, a circulating pump is used to circulate the water in the hot water storage tank between a heat source such as a heat pump and a fuel cell to supply hot water for hot water supply. Generate and store hot water in the hot water storage tank.

In the hot water storage water heater, for example, when the outside air temperature decreases in winter, the water in the circulation pipe connected between the hot water storage tank and the heat source may freeze, and hot water may not be supplied. It was Also, if the water in the pipe freezes, the pipe may break due to expansion during freezing, or the pipe may crack.
There is a risk of water leakage, and this water leakage causes insufficient water circulation, which causes equipment such as heat sources to malfunction.

[0004]

When a heat source such as a heat pump unit is operated and hot water is circulated in the pipe when the outside air temperature is lowered in order to prevent freezing in the pipe of the hot water storage type water heater. However, since electric power is consumed to operate the heat source for freeze prevention, there is a problem that the annual energy consumption efficiency COP is reduced. Also,
There is a problem that the amount of power used increases and the burden of power charges on the user increases.

In particular, in the hot water storage type water heater, the heat source is operated during the night when the electricity charge is low (for example, from 11:00 pm to 7:00 am) to heat the water in the hot water storage tank to raise the temperature and store hot water. By the way, the hot water in the hot water storage tank is used during the daytime other than the night when the power charge is high, so that the power charge for the user is suppressed.

However, if the heat source is operated as described above in order to prevent the piping from freezing during the daytime, the daytime electricity, which has a high electricity rate, will be consumed, and the burden on the user of the electricity rate will increase significantly. The problem occurs.

Further, in order to avoid the operation of the heat source for preventing freezing as much as possible, the hot water in the hot water tank is supplied to the pipe when the outside air temperature drops, and the water whose temperature has dropped in the pipe reaches the upper part of the hot water tank. When returned, the balance of the temperature layers of the high temperature water and the low temperature water stored in the hot water storage tank is lost, and the hot water in the hot water storage tank is made uniform overall, making it impossible to supply high temperature water. Occurs.

Therefore, an object of the present invention is to prevent freezing of piping and to maintain a temperature layer in a hot water storage tank while suppressing an increase in power consumption of a hot water storage water heater as much as possible.

[0009]

Therefore, the first invention is
In a hot water storage type hot water supply device having a hot water supply circuit that circulates water between a hot water storage tank and a heat source for heating by a circulation pump, and a hot water supply circuit capable of discharging hot water from the hot water storage tank, a temperature detector for detecting the outside air temperature and the temperature. Storage means for storing a set temperature for starting operation of the circulation pump when the detected temperature of the detector decreases; and the circulation when the detected temperature of the temperature detector has decreased to the set temperature stored in the storage means. And a control means for starting the operation of the pump.

A second aspect of the present invention is a hot water storage type hot water dispenser comprising a hot water supply circuit for circulating water between a hot water storage tank and a heat source for heating by a circulation pump and allowing hot water to be discharged from the hot water storage tank. A temperature detector for detecting a water temperature in a pipe connected between the tank and the heating heat source; and a storage means for storing a first set temperature and a second set temperature lower than the first set temperature. When the temperature detected by the temperature detector has dropped to the first set temperature stored in the storage means, the circulation pump is started to operate, and the low temperature water in the lower portion of the hot water storage tank is introduced into the pipe. The second temperature is circulated, and the temperature detected by the temperature detector is stored in the storage means.
When the temperature falls to the set temperature, the control means starts the operation of the circulation pump to circulate the high temperature water in the upper part of the hot water storage tank in the pipe.

According to a third aspect of the invention, when the temperature detected by the temperature detector is lowered to the second set temperature stored in the storage means and the circulation pump is operating, the inside of the hot water tank is A return pipe for returning the return water supplied from the upper part of the above and circulated in the pipe to the intermediate layer of the hot water storage tank is provided.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of a heat pump water heater serving as a hot water storage water heater to which the present invention is applied. This heat pump water heater exchanges heat between a refrigerant compressed by a compressor and water by a heating heat exchanger. A heat pump unit 100 as a heat source including a refrigerant circuit;
A hot water storage tank unit 200 including a hot water storage tank for storing high-temperature water whose temperature has risen in the heat pump unit 100;
A hot water supply circuit 300 that circulates water between the hot water storage tank and the heating heat exchanger by a circulation pump and allows hot water to be discharged from the hot water storage tank is a main component.

A refrigerant circuit provided in the heat pump unit 100 includes a compressor 1 which sucks and compresses a refrigerant to make it into a high temperature and high pressure, a refrigerant-to-water heat exchanger 2 for heating for exchanging heat between the refrigerant and water, and an electric type. Expansion valve 3, evaporator 4 as an outdoor heat exchanger for exchanging heat between outside air and refrigerant, accumulator 5
And so on.

The hot water tank unit 200 is a hot water tank for storing hot water and a control board 9 to which a kitchen remote controller (remote controller) 7 operated in the kitchen and a bath remote controller (remote controller) 8 operated in a bathroom are connected. The control board 9 is provided with a microcomputer (hereinafter referred to as “microcomputer”) 40 and the like as control means for controlling the heat pump water heater. The kitchen remote controller 7 and the bath remote controller 8 are provided with a time display device and the like.

The hot water supply circuit 300 includes a water supply pressure reducing valve 11 with a check valve for supplying tap water to the hot water storage tank 10 and the hot water storage tank 1.
0 hot water outlet pipe 12 for drawing hot water from the upper portion, bypass pipe 14 from the outlet side of the water supply pressure reducing valve 11 to the mixing valve 13 connected to the hot water outlet pipe 12, hot water filling pipe 15 branching from the hot water outlet pipe 12 to the bath 31 A flow rate control valve 16 connected to the hot water filling pipe 15, a pressure relief valve 17 connected to the hot water outlet pipe 12 upstream of the mixing valve 13, a lower end of the hot water storage tank 10 and the refrigerant-to-water heat exchanger 2. A forward pipe 18 connected to the inlet side, a circulation pump 19 connected in the middle of the forward pipe 18 to supply water from the hot water storage tank 10 to the refrigerant-to-water heat exchanger 2, and the circulation pump 19 An on-off valve (hereinafter referred to as "water inlet valve") 20 connected to the upstream side of the hot water circulation pipe 21, which branches from a forward pipe 18 between the circulation pump 19 and the water inlet valve 20 to a hot water outlet pipe 12, Connect in the middle of this high-temperature water circulation pipe 21 The on-off valve (hereinafter, "high temperature valve" hereinafter) 22, a first return pipe 23 connected between the upper end portion of the outlet side and the hot water storage tank 10 of the refrigerant-water heat exchanger 2, the first
Flow control valve 24 as a flow control means connected in the middle of the return pipe 23, a second return pipe 25 branched from the middle of the first return pipe 23 and connected to the lower portion of the hot water storage tank 10, An on-off valve (hereinafter,
A "return valve" 26 is connected by piping.

A temperature sensor (hereinafter referred to as "inlet temperature sensor") 28 as an outside air temperature sensor and a temperature sensor (hereinafter referred to as "outlet temperature sensor") are provided on the inlet side and the outlet side of the refrigerant-to-water heat exchanger 2, respectively. 29), and a temperature sensor (hereinafter, referred to as an outside air temperature sensor) in the middle of the first return pipe 23 in the hot water tank unit 200.
A "hot water tank inlet temperature sensor" 30 is provided.

Next, description will be given based on the control block diagram of FIG. The microcomputer 40 provided on the control board 9 on the side of the hot water tank unit 200 has a CPU (Central Processing Unit) 41 for centrally controlling the operation of the hot water tank unit 200 of the present heat pump water heater, and a storage device for storing various data. RAM (random access
Memory 42, and a ROM (read only memory) 43 for storing programs related to the hot water supply operation and the freeze prevention operation. The ROM 43 stores the maximum boiling amount, which is the maximum amount of hot water to be boiled in the middle of the night in the hot water tank 10 by using, for example, the midnight power, the minimum amount of hot water to start additional boiling, and the like in the table shown in FIG. The amount of stored hot water at the end of additional heating, which is the amount of hot water to stop the additional heating, is stored as the mode for heating (additional heating) from mode 1 to mode 7, and these modes are changed based on changes in the amount of stored hot water. The program is set. Based on the data stored in the RAM 42, the CPU 41 comprehensively controls the hot water supply operation of the heat pump water heater according to the program stored in the ROM 43 and the mode. Then, normally, the microcomputer 40 controls the water heater so as to boil all the capacity in the hot water storage tank 10 to a predetermined temperature.

Further, the kitchen remote controller CPU 7a is connected to the microcomputer 40 by a signal line, and the kitchen remote controller CPU 7a is provided with a boiling amount switch 7b for setting the amount of hot water filling when hot water is supplied to the bathtub 31 and the above mode. The mode changeover switch 7c is connected.

A microcomputer (hereinafter referred to as "microcomputer") is used as a control means on the heat pump unit 100 side.
50 is a CPU 51 that integrally controls the operation of the heat pump unit 100, a RAM 52 as a storage device that stores various data, and a ROM 5 that stores a program related to the operation of the heat pump unit 100.
It consists of three. Then, the compressor 1, the expansion valve 3,
The inlet temperature sensor 28, the outlet temperature sensor 29, and the hot water tank inlet temperature sensor 30 are connected to the microcomputer 50 by signal lines.

The microcomputer 40 and the microcomputer 50 are connected to the signal line 5
5, the temperatures detected by the inlet temperature sensor 28, the outlet temperature sensor 29, and the hot water tank inlet temperature sensor 30 are transmitted to the microcomputer 40 via the microcomputer 50 and the signal line 55, and are stored in the RAM 42 at any time. Further, in the RAM 42, a first set temperature (for example, 5 ° C.) at the time of starting the freeze preventive operation by circulation of low-temperature water described later and a second set temperature at the end of the freeze preventive operation (for example, 10 ° C.).
℃), a third set temperature (for example, 2 ° C.) when starting the freeze preventive operation by circulating hot water, and a fourth set temperature (for example, 10 ° C.) when ending the freeze preventive operation are stored. There is.

The capacity of the hot water storage tank 10 is, for example, 370 liters, and hot water temperature detection sensors TS1, TS2, TS3, TS4, TS5, TS6 and TS7 are provided in the hot water storage tank 10 from the bottom to the top. This water heater has a maximum temperature of 55
Since the temperature is up to 0 ° C., when the hot water temperature detected by each sensor is 55 ° C. or higher, it is determined that there is residual hot water from the upper end of the hot water tank 10 to that position. At this time, the detection sensor T
The location of S1 is 350 liters of residual hot water, 300 liters of TS2, 250 liters of TS3, and TS4.
Is 200 liters, TS5 is 150 liters, TS6 is 100 liters, and TS7 is 50 liters.

Here, the outside temperature (for example, 25 ° C.) by the hot water tank inlet temperature sensor 30, the capacity of the heat pump (for example, 5.0 kW), the boiling temperature (for example, 75 ° C.), and the non-return detected by the feed water temperature sensor 56. Supply temperature (eg, 20 ° C.) of tap water supplied to the hot water storage tank 10 via the valve-equipped tap water pressure reducing valve 11, detection temperature of the hot water temperature detection sensor TS3 (eg, 63 ° C.), and detection temperatures of the hot water temperature detection sensors TS1 and TS2 Data such as (for example, 50 ° C.) is stored in the RAM 42 of the microcomputer 40, and the microcomputer 40 determines the amount of hot water stored in the hot water storage tank 10 based on these data.

That is, first, the microcomputer 40 searches for a combination of detection sensors including the boiling water temperature 55 ° C. between the two detection sensors from the seven hot water temperature detection sensors, and detects a temperature higher than 55 ° C. The detection temperature of the detection sensor
i, the remaining hot water amount is Lhi, the detection temperature of the detection sensor detecting a low temperature is Tlo, and the remaining hot water amount is Llo, and the hot water storage amount (remaining hot water amount) in the hot water storage tank 10 reaching 55 ° C. Lz = Lz = (Thi−55) / (Thi
The microcomputer 40 calculates from −Tlo) × (Llo−Lhi) + Lhi.

Therefore, the residual hot water amount Lz reaching 55 ° C.
Is (63-55) / (63-50) x (300-25
0) +250 to about 286 liters, the microcomputer 40 determines.

Next, circulation flow rate (boiling amount per minute)
Is calculated by dividing the heating amount per minute by the heat pump by the temperature obtained by subtracting the water temperature from the boiling temperature. Specifically, the circulation flow rate = (heat pump capacity P × 860 (K
cal) / 60 (minutes) / (boiling temperature Tp− (outside air temperature Tt × 0.8 + 3)), which is calculated by the microcomputer 40. That is, the feed water temperature (water temperature entering the refrigerant-to-water heat exchanger 2) at which the predetermined capacity is constant is calculated by using the outside air temperature value from the conversion formulas obtained in various performance tests.

Therefore, the circulation flow rate is (5 × 860/60)
/(75-(25×0.8+3) to about 1.38 liters / minute, the microcomputer 40 determines. That is, because of the characteristics of the heat pump (especially when the refrigerant is CO ₂ ), the boiling temperature is fixed, Water supply temperature (water temperature entering the refrigerant-to-water heat exchanger 2)
When the temperature rises, the heating capacity gradually decreases even if the frequency of the compressor 1 is kept constant, and the curve of the rise in water temperature and the decrease in capacity are not completely linear. Including the protection of the inlet water temperature, the frequency of the compressor 1 is lowered stepwise in accordance with the inlet water temperature. As a result, if the inlet water temperature fluctuates, an operation is performed to maintain a substantially constant circulation flow rate under the same outside air temperature conditions. Will be controlled.

As described above, the microcomputer 40 determines the amount of hot water stored in the hot water storage tank 10 and calculates the circulating amount at the time of boiling (at the time of additional boiling).

The control during hot water supply from the heat pump water heater will be described below.

When hot water is supplied from the hot water storage state in the hot water storage tank 10 as shown in FIG. 4A (the hatched portion represents the hot water storage amount of the entire capacity) and hot water is used,
Water is supplied from a water supply pressure reducing valve 11 with a check valve so that the hot water storage tank 10 is filled with water. As hot water is used, the amount of hot water stored gradually decreases, and the hot water storage state shown in FIG. further,
The amount of hot water supplied is reduced and becomes smaller than the minimum amount of hot water storage (for example, 150 liters in the case of mode 4) as shown in (c), and the temperature detected by the detection sensor TS6 is 55 ° C., which is the temperature determined to be the hot water storage state. When the temperature further decreases, the microcomputer 40 determines that the amount of stored hot water has become smaller than the position of the detection sensor, outputs an operation signal to the microcomputer 50 on the heat pump unit 100 side, and causes the heat pump water heater to start boiling operation.

That is, the compressor 1 starts operation, and the compressor 1
The refrigerant, which has been compressed by and has reached a high temperature, is supplied to the refrigerant-to-water heat exchanger 2. Then, the circulation pump 19 is activated and the water at the bottom of the hot water storage tank 10 is supplied to the refrigerant-to-water heat exchanger 2 via the water inlet valve 20, and heat exchange between the refrigerant and water is started.
As a result, the refrigerant loses heat and condenses, and the temperature of the water rises due to the heat of condensation of the refrigerant to become hot water, that is, hot water, and returns to the hot water storage tank 10 via the flow rate control valve 24.

At this time, the microcomputer 40 operates on the basis of the temperature detected by the outlet temperature sensor 29 to control the opening of the flow rate control valve 24 so that the temperature is substantially set.
Hot water whose temperature has risen to (° C.) is supplied from the first return pipe 23 to the upper part of the hot water storage tank 10. As a result, the upper layer in the hot water storage tank 10 becomes hot water and the lower layer becomes water, and the hot water layer and the water layer do not mix with each other over time, and the hot water layer increases and the water layer decreases. Then, in a normal operating state (corresponding to the case of mode 7), the hot water storage tank 10 is finally filled with hot water. For example, when the boiling control mode is mode 4,
As shown in (c) of FIG. 5, the amount of hot water stored rises up to 200 liters, which is the amount at the end of additional heating, and the detection sensor T
When the detected temperature of S5 becomes 55 ° C. or higher, the CPU 41 operates and the microcomputer 40 outputs a stop signal to the circulation pump 19 and also outputs a stop signal to the compressor 1 via the microcomputer 50, and the boiling operation ends. .

As described above, during the additional heating operation, the additional heating operation is controlled according to the mode of the additional heating control shown in FIG. 3. Below, the control when changing the mode of the additional heating control will be described with reference to FIG. A description will be given based on the flowchart.

First, it is determined whether the boiling control mode (operation mode) is manual or automatic. In the case of manual operation, the boiling control mode is set to mode 1 based on the operation of the boiling amount setting switch 17b. It is set between 3 and 3. That is, the boiling amount is divided into, for example, three stages of a large amount, a medium amount, and a small amount. Mode 3 is set when the amount is large, mode 2 is set when the amount is intermediate, and mode 1 is set when the amount is small. The operation of the heat pump water heater is controlled according to the set mode.

When the boiling control mode (operating mode) is automatic, for example, the boiling control mode 3, which is the standard mode, is automatically set when the heat pump water heater is powered on. Therefore, the amount of hot water stored is reduced by supplying hot water from the hot water storage tank 10, and the temperature detected by the detection sensor TS6 is 55 ° C.
The microcomputer 40 determines that the temperature has become lower and the hot water storage amount has decreased to less than 100 liters (determination A). In accordance with this determination, a timer (not shown) provided in the microcomputer 40 starts operating. Then, after that, when the amount of stored hot water does not fall below 50 liters, that is, when the detection sensor TS7 continues to detect a temperature of 55 ° C. or higher, the boiling control mode 3 is set to a predetermined time (preliminarily set in the timer). For example, 3 days).

If the amount of hot water stored decreases before the elapse of a predetermined time and the temperature detected by the detection sensor TS7 falls below 55 ° C., the microcomputer 40 determines that the amount of hot water stored has fallen below 50 liters ( Judgment B), the boiling control mode is shifted to a mode one rank higher, that is, the mode 4 having a larger mode number. Therefore, the minimum hot water storage amount at the start of additional heating is increased from 100 liters to 150 liters, and the end hot water storage amount of the additional heating operation is increased from 150 liters to 200 liters.

Further, when the microcomputer 40 determines that there is a hot water storage amount of 100 liters or more in the hot water storage tank 10 based on the temperature detected by the detection sensor TS6 (decision C), a timer (not shown) operates. When the amount of stored hot water of 100 liters or more is maintained for a preset predetermined period (for example, 3 days), the timer counts up, the microcomputer 40 operates, and the mode is one rank lower, that is, the mode number. Shifts to mode 2, which is a small mode. As a result, the maximum boiling amount is reduced from 370 liters to 300 liters.

In each boiling control mode, the same judgment as in the above mode 3 is made. For example, in mode 5, when the stored hot water amount of 100 liters or more is maintained for a predetermined period, the timer counts up, The microcomputer 40 operates and shifts to a mode one rank lower, that is, a mode 4 having a smaller mode number. As a result, the minimum hot water storage amount at the start of additional heating is reduced from 200 liters to 150 liters, and the end hot water storage amount of the additional heating operation is reduced from 250 liters to 200 liters. Similarly, in modes 4 to 7, when the amount of stored hot water of 100 liters or more is maintained for a predetermined period, the timer counts up, the microcomputer 20 operates, and the mode is one rank lower.
That is, the mode shifts to a mode having a small mode number. As a result, both the minimum hot water storage amount at the start of additional heating and the end hot water storage amount at the additional heating operation are decreased by 50 liters.

As a result, when the amount of hot water supply is large, that is, when the load used is large, it is possible to shift the mode number to the larger one and appropriately cope with the load.
When the amount of hot water supply is small and the usage load is small, the mode number is shifted to the smaller one to reduce the maximum boiling amount at midnight,
Further, by decreasing both the minimum amount of hot water storage at the start of additional heating and the amount of end hot water storage at the additional heating operation, a wide operation corresponding to the usage load with one hot water tank 10 capacity, that is, the amount of hot water storage or the additional heating amount. It is possible to control the heat loss due to heat dissipation as much as possible, and to improve the operating efficiency of the heat pump water heater,
That is, the hot water supply efficiency is improved.

The antifreezing operation of the heat pump water heater whose hot water supply operation is controlled as described above in the winter season will be described below.

When the operation of the heat pump unit 100 is stopped, the outside air temperature decreases and the inlet temperature sensor 2
8, outlet temperature sensor 29 or hot water tank inlet temperature sensor 3
When any of the detected temperatures of 0 reaches the first set temperature (5 ° C.), the microcomputer 40 operates to maintain the water inlet valve 20 in the open state, open the return valve 26, and close the flow rate adjusting valve 24. The circulation pump 19 is operated.

Therefore, by operating the circulation pump 19, the low temperature water in the low temperature layer stored in the lower layer 10a of the lower part of the hot water storage tank 10 is cooled by the water inlet valve 20, the circulation pump 19, the outflow pipe 18, and the heat pump unit 100. The heat exchanger 2, the first return pipe 23, the second return pipe 25, and the return valve 26 circulate with the lower layer 10a not in the hot water storage tank 10, and the forward pipe 18 and the first return pipe 23, especially the heat pump unit 100. The freezing of the portion located between the hot water tank unit 200 and the hot water tank unit 200 is prevented.

Then, by the above-mentioned freezing prevention operation, the forward pipe 1
8 and the temperature of circulation circuits such as the first return pipe 23 increase,
The temperatures detected by the inlet temperature sensor 28, the outlet temperature sensor 29, and the hot water tank inlet temperature sensor 30 are all the second set temperature (1
At 0 ° C.), the microcomputer 40 operates to close the return valve 26, open the flow rate adjusting valve 24, and stop the operation of the circulation pump 19. As a result, the circulation of the low-temperature water from the hot water storage tank 10 is stopped, the freeze prevention operation by supplying the low-temperature water with reduced power is terminated, and the increase in power consumption due to the freeze prevention operation can be minimized.

However, when the low temperature water in the hot water storage tank 10 as described above is circulated through the outflow pipe 18 and the first and second return pipes 23 and 25 to prevent freezing, the outside air temperature further decreases. As a result, the temperatures of the outflow pipe 18 and the first return pipe 23 decrease, and the detected temperature of either the inlet temperature sensor 28, the outlet temperature sensor 29, or the hot water tank inlet temperature sensor 30 becomes the third temperature.
At the set temperature (2 ° C) of, the microcomputer 40 operates,
The water inlet valve 20 is closed, the high temperature valve 22 is opened, the return valve 26 is kept open, the flow rate adjusting valve 24 is kept closed, and the circulation pump 19 is operated.

Therefore, by operating the circulation pump 19, the high temperature water stored in the upper portion (upper layer) of the hot water storage tank 10 is heated by the high temperature valve 22, the high temperature water circulation pipe 21, the forward pipe 18, and the circulation pump 1.
9, the refrigerant-to-water heat exchanger 2, the first return pipe 23, the second return pipe 25 and the return valve 26 circulate with the lower layer of the hot water storage tank 10. As a result, the forward pipe 18 and the first return pipe 23, especially the heat pump unit 100 and the hot water tank unit 20.
Hot water flows to the part located between 0 and 0, and the freezing of this part is more surely prevented.

By the freezing prevention operation by supplying the high temperature water, the temperature of the circulation path such as the outflow pipe 18 and the first return pipe 23 rises, and the inlet temperature sensor 28, the outlet temperature sensor 29, and the hot water tank inlet temperature sensor. When all the detected temperatures of 30 reach the fourth set temperature (10 ° C.), the microcomputer 40 operates to close the high temperature valve 22 and the return valve 26, open the water inlet valve 20 and the flow rate adjusting valve 24, and further circulate the pump. The operation of 19 is stopped. As a result, the circulation of the low temperature water from the hot water storage tank 10 is stopped, the freeze prevention operation by supplying the high temperature water is completed, and the increase in power consumption due to the freeze prevention operation can be minimized.

Next, a second embodiment will be described with reference to FIG. In the first embodiment, the second return pipe 25 is provided at the bottom of the hot water storage tank 10 by branching from the middle of the first return pipe 23.
While the return valve 26 is connected in the middle of the second return pipe 25 by piping, the second embodiment branches off from the middle of the first return pipe 23 to store hot water. The second return pipe 25 reaching the intermediate layer 10b, which is the middle portion of the tank 10, is connected, and a return valve 26 and a check valve 27 are connected in the middle of the second return pipe 25. Different. That is, the tip end of the second return pipe 25 of the second embodiment faces the intermediate layer 10b (the middle layer between the high temperature layer and the low temperature layer of the hot water in the hot water storage tank 10) which is the intermediate portion of the hot water storage tank 10. ing.

When the hot water is circulated as described above to perform the freeze prevention operation, the return water is returned to the second return pipe 25.
To return to the intermediate layer 10b, which is the intermediate portion of the hot water storage tank 10, through the upper layer 10c, which returns the intermediate temperature water to the upper portion.
It is possible to avoid affecting the high temperature water layer and the low temperature water layer of the lower layer 10a below. That is, the lower layer 10 of the hot water storage tank 10
When the intermediate temperature water that has passed through the going pipe 18 and the first return pipe 23 is returned to the low temperature water layer of a or the high temperature water layer of the upper layer 10c, the hot water layer in the hot water storage tank 10 is destroyed and the hot water storage tank 10 There is a risk that the temperature difference between the upper and lower parts will disappear and high-temperature water cannot be supplied, but by returning to the intermediate layer 10b, layer collapse in the hot water storage tank 10 can be prevented, and high-temperature water can be stably supplied.

Due to the above-mentioned operation for preventing freezing, the temperature of the circulation path such as the outflow pipe 18 and the first return pipe 23 rises, and the temperatures detected by the inlet temperature sensor 28, the outlet temperature sensor 29, and the hot water tank inlet temperature sensor 30 are all detected. Fourth set temperature (10 ° C)
Then, the microcomputer 40 operates to close the high temperature valve 22 and the return valve 26, open the water entry valve 20 and open the flow rate adjusting valve 24.
Is opened, and the operation of the circulation pump 19 is stopped. As a result, the circulation of the high temperature water is stopped, the freezing prevention operation ends, and the use of the high temperature water in the hot water storage tank 10 due to the freezing prevention operation can be minimized.

In the above embodiment, the flow rate adjusting valve 24 is closed during the temperature control of the high temperature water supplied to the hot water storage tank 10 during operation and the freeze prevention operation, and the circulating water is circulated to the upper part (upper layer) of the hot water storage tank 10. However, it is also possible to provide an electromagnetic valve in series with the flow rate adjusting valve 24 and to close this electromagnetic valve during freeze prevention operation.

Further, by not opening the water inlet valve 20 and opening the high temperature valve 22 during the freeze prevention operation, the hot water in which the high temperature water in the upper part and the low temperature water in the lower part of the hot water storage tank 10 are circulated is circulated. Freezing of 18 and the first return line 23 may be prevented.

By the freezing prevention operation, the hot water storage tank 1
0, the water temperature of the lower layer 10a decreases, but when the heat pump unit 100 is in operation, the heat pump unit 100
The lower the temperature of the water flowing into the refrigerant, the better the heat exchange efficiency in the refrigerant-to-water heat exchanger 2.

Although the embodiments of the present invention have been described above, various alternatives, modifications or variations can be made by those skilled in the art based on the above description, and the various alternatives described above are possible without departing from the spirit of the present invention. It is intended to include examples, modifications or variations.

[0053]

As described above, the present invention uses low-temperature water or high-temperature water in the hot-water storage tank when the outside air temperature of the hot-water storage water heater decreases, while suppressing an increase in power consumption of the hot-water storage water heater as much as possible. , It is possible to prevent the freezing of piping.

Further, during the freeze prevention operation, the temperature layer in the hot water storage tank can be maintained and the high temperature water can be stably supplied.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a heat pump water heater.

FIG. 2 is a control block diagram.

FIG. 3 is a diagram showing a table of a maximum boiling amount for each mode, a minimum hot water storage amount at the start of additional heating, and a hot water storage amount at the end of additional heating.

FIG. 4 is a diagram for explaining changes in the amount of hot water stored during the additional heating operation.

FIG. 5 is a diagram showing a flowchart.

FIG. 6 is a circuit explanatory diagram of a heat pump water heater according to a second embodiment.

[Explanation of symbols]

1 compressor 2 Refrigerant-to-water heat exchanger (heating heat exchanger) 10 Hot water storage tank 18 going pipe 23 First return pipe 25 Second return pipe 40 microcomputer 41 CPU 42 RAM 43 ROM 50 microcomputer 100 heat pump unit 200 hot water storage unit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Nakayama             1 Otsuki-cho, Ashikaga City, Tochigi Prefecture Sanyo Electric Air Conditioning             Within the corporation (72) Inventor Takuyuki Yajima             1 Otsuki-cho, Ashikaga City, Tochigi Prefecture Sanyo Electric Air Conditioning             Within the corporation (72) Inventor Tadashi Ohata             1 Otsuki-cho, Ashikaga City, Tochigi Prefecture Sanyo Electric Air Conditioning             Within the corporation

Claims (3)

[Claims] 1. A hot water storage water heater having a hot water supply circuit that circulates water between a hot water storage tank and a heat source for heating by a circulation pump and allows hot water to be discharged from the hot water storage tank. And storage means for storing the set temperature for starting the circulation pump when the detected temperature of the temperature detector is lowered, and the detected temperature of the temperature detector up to the set temperature stored in the storage means. A hot water storage type hot water supply device, comprising: a control means for starting the operation of the circulation pump when the temperature falls. 2. A hot water storage type hot water supply device comprising a hot water supply circuit that circulates water between a hot water storage tank and a heating heat source by a circulation pump, and a hot water supply circuit capable of discharging hot water from the hot water storage tank. A temperature detector for detecting a water temperature in a pipe connected between the first temperature and a second temperature lower than the first temperature, and a temperature detector. When the detected temperature of is decreased to the first preset temperature stored in the storage means, the operation of the circulation pump is started to circulate the low temperature water in the lower portion of the hot water storage tank in the pipe, Control for starting the operation of the circulation pump to circulate the high temperature water in the upper part of the hot water tank in the pipe when the temperature detected by the detector has dropped to the second set temperature stored in the storage means. Having means Hot water storage type water heater characterized by. 3. When the temperature detected by the temperature detector has dropped to the second set temperature stored in the storage means and the circulation pump is operating, the temperature is supplied from above the hot water tank. The hot water storage type water heater according to claim 2, further comprising a return pipe for returning the return water circulated in the pipe to the middle layer of the hot water storage tank.