JPH0411775B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hot water storage type electric water heater used in homes and the like, and particularly to an electric water heater that effectively utilizes cheap late-night electricity.

(Prior Art) Conventionally, as described in Japanese Utility Model Application Publication No. 52-98857, a heat exchanger has a heater built into the outside of a hot water storage tank with a water supply pipe connected to the bottom and a hot water outlet pipe connected to the top. The outlet of this heat exchanger is connected to the upper part of the hot water storage tank via a circulation pipe, and
An electric water heater is known in which the inlet of the heat exchanger is connected to the lower part of a hot water storage tank via another circulation pipe. This electric water heater has a circulation pipe from the hot water tank,
A circulating flow is generated that passes through the heat exchanger and circulation pipes and returns to the hot water storage tank, thereby gradually boiling the water in the hot water storage tank.

By the way, even if you boil all the water in the hot water storage tank late at night when electricity rates are low, the temperature of the hot water in the tank will drop as you use it during the day, so you should heat it up during the day as well. There must be. However, with the above conventional electric water heater,
Even during the day when electricity prices are high, the entire water in the hot water storage tank is circulated and heated, which is not only inefficient but also uneconomical.

In addition, as described in Japanese Utility Model Publication No. 61-43180, a main heater that generates heat using late-night power is installed in a hot water storage tank with a water supply pipe connected to the bottom and a hot water outlet pipe connected to the top. Electric water heaters are known that are equipped with an auxiliary heater that generates heat with less power consumption. This electric water heater uses the main heater to boil water in the middle of the night, and then uses the auxiliary heater to compensate for the drop in temperature during the day, thereby reducing the use of expensive daytime electricity as much as possible, and keeping water at a predetermined temperature during daytime use. It is designed so that it can be obtained.

However, with this conventional electric water heater, 2
Since two heaters are used and the heater control circuit is complicated, there are problems such as high cost.

(Problems to be Solved by the Invention) As mentioned above, conventional electric water heaters that have a heat exchanger installed outside the hot water storage tank have a structure that circulates and heats the entire water inside the hot water storage tank even during the day. Because of this, it is inefficient and uneconomical, and
Electric water heaters with two heaters installed in the hot water storage tank have had problems such as being expensive.

The present invention aims to solve the above-mentioned problems, and provides an electric water heater that can be used efficiently and economically using late-night electricity, and can be obtained at low cost.

(Means for Solving Problems) The electric water heater of the present invention has a heater built-in for both nighttime power and daytime power outside of a hot water storage tank in which a water supply pipe is connected to the bottom and a hot water outlet pipe is connected to the top. A circulation pipe and the hot water storage, in which an exchanger is provided, an outlet of the heat exchanger is connected to an upper part of the hot water storage tank via a circulation pipe, and an inlet of the heat exchanger is connected to a lower part of the hot water storage tank. When electricity is applied at night, the lower part of the hot water storage tank is connected to the circulation pipe connected to the middle part of the tank, and when electricity is applied during the day, the lower part of the hot water storage tank is connected to the inlet of the heat exchanger. They are connected to each other via switching valves that communicate with the inlets.

(Function) In the electric water heater of the present invention, for example, when energizing late at night when electricity rates are low, the lower part of the hot water storage tank and the heat exchanger are communicated by the switching valve, and the middle part of the hot water storage tank is connected to the heat exchanger. and cut off. Then, the water is heated by the heater in the heat exchanger, and
A circulating flow is generated from the hot water storage tank to the hot water storage tank again via a circulation pipe connected to the lower part of the hot water storage tank, a heat exchanger, and a circulation pipe connected to the upper part of the hot water storage tank. At this time, the entire inside of the hot water storage tank becomes a circulating flow path, so the water in the entire hot water storage tank is boiled and a large amount of hot water is obtained. On the other hand, when electricity is turned on during the day when electricity costs are high, the switching valve connects the middle part of the hot water storage tank and the heat exchanger.
The lower part of the hot water storage tank is isolated from the heat exchanger. At this time, only the upper part of the hot water storage tank becomes a path for circulation flow, so only the water in the upper part of the hot water storage tank is mainly boiled to compensate for a drop in hot water temperature or as a small water supply when there is a hot water shortage. Used when capacity is required.

(Example) Hereinafter, one example of the electric water heater of the present invention will be described based on the drawings.

1 is a hot water storage tank, one end of a water supply pipe 2 is connected to the lower bottom of this hot water storage tank 1, and the other end of this water supply pipe 2 is connected to a water supply source (not shown) such as a tap. ing. In addition, the above hot water storage tank 1
One end of a tap pipe 3 is connected to the upper top, and the other end of the tap pipe 3 is connected to a hot water outlet, such as a faucet (not shown), which can be opened and closed.

A heat exchanger 4 is disposed outside the hot water storage tank 1 at a height corresponding to the lower part of the hot water storage tank 1, and has a built-in heater 5 for both nighttime power and daytime power. One end of a first circulation pipe 6 is connected to the outlet 4a of the heat exchanger 4, and the other end of the first circulation pipe 6 is located near the upper top of the hot water storage tank 1. and is connected to the hot water outlet pipe 3. Further, one end of a second circulation pipe 7 is connected to the inlet 4b of the heat exchanger 4, and the other end of the second circulation pipe 7 is an outlet of a switching valve 8 consisting of a three-way valve. 8a.

In addition, this switching valve 8 has a first inlet 8b that is opened when electricity is applied during the late-night electricity application period and closed during the daytime electricity application, and a second inlet port 8b that is opened during the daytime electricity application and closed when the nighttime electricity is applied. It has an entrance 8c. One end of a third circulation pipe 9 is connected to the first inlet 8b, and the other end of the third circulation pipe 9 is connected to the lower bottom of the hot water storage tank 1. On the other hand, one end of a fourth circulation pipe 10 is connected to the second inlet 8c, and the other end of the fourth circulation pipe 10 is connected to the middle part of the hot water storage tank 1 in the height direction. It is connected. Note that the connection portion of the fourth circulation pipe 10 to the hot water storage tank 1 is located above the heat exchanger 4.

Next, the operation of the above embodiment will be explained.

Water is supplied into the hot water storage tank 1 via a water supply pipe 2 from a water supply source.

When applying power late at night, the first switch valve 8
The second inlet 8b is opened, and the second inlet 8c is closed. When the heater 5 of the heat exchanger 4 is energized in this state, the water is heated, and as shown by the arrow in FIG. 4. Circulating flow as natural convection that circulates through the first circulation pipe 6 and the hot water storage tank 1 is generated.
Since this circulating flow passes through the entire interior of the hot water storage tank 1, the temperature of the water within the entire interior of the hot water storage tank 1 is raised and gradually boiled.

During the day, the large volume of hot water that was boiled late at night and stored in the hot water storage tank 1 as described above is mainly used. That is, when a faucet or the like is opened, hot water is supplied from the hot water storage tank 1 through the hot water outlet pipe 3.

However, as the water temperature in the hot water storage tank 1 decreases as hot water is used, it is necessary to heat the water during the day as well. In such a case, the late-night power supply is cut off, the switching valve 8 closes the first inlet 8b, and the second inlet 8b is closed.
Since the inlet 8c of the water tank is open, when the heater 5 is energized in this state, the water is heated and the water flows through the hot water storage tank 1, the fourth circulation pipe 10, and the second It circulates along the circulation pipe 7, the heat exchanger 4, the first circulation pipe 6, and the hot water storage tank 1. Since this circulating flow passes only through the upper part of the hot water storage tank 1, only the water in the upper part of the hot water storage tank 1 is heated and boiled.

In this case, since the connection part of the fourth circulation pipe 10, which is the outlet from the hot water storage tank 1, to the hot water storage tank 1 is located above the heat exchanger 4, the inside of the heat exchanger 4 and the hot water storage tank are connected to each other. Due to the relationship between the specific gravity of the water in the upper and lower parts of hot water storage tank 1, a circulating flow, that is, convection, occurs reliably through the upper part of hot water storage tank 1 as the heat exchanger 4 heats the water.

Normally, the amount of hot water used at one time is not so large, so if only the water in the upper part of the hot water storage tank 1 connected to the hot water outlet pipe 3 is boiled, sufficiently hot water can be used.

As mentioned above, when energizing the heater 5 using expensive daytime electricity, only the water in the upper part of the hot water storage tank 1, that is, a relatively small amount of water, is circulated, so that this water can be used more efficiently. It is economical because it heats up and consumes less power.

According to the above configuration, since only one heater 5 and its control circuit are required, the cost can be reduced. In addition, the daytime power supplied to the heater 5 is limited to a specific time when hot water is used, and there is no need to constantly supply the power. The load capacity of the heater 5 is substantially reduced compared to the 200V power supply used as electric power, and an increase in the contracted current capacity of a general household power source can be suppressed, making it possible to economically use an electric water heater with a small contracted current capacity. can.

In addition, the switching valve 8 is a four-way valve, and the inlet 4b of the heat exchanger 4 is placed at two different heights of the lower part and the middle part of the hot water storage tank 1 depending on the amount of remaining hot water. For example, connect each via
There may be three or more circulating flow paths during daytime power use. Increasing the number of circulation flow paths in this way increases the range of adjustment for the amount of hot water used.

(Effects of the Invention) According to the present invention, the outlet of the heat exchanger is connected to the upper part of the hot water storage tank, and the inlet of the heat exchanger is connected to the middle and lower parts of the hot water storage tank through the switching valves. In particular, this switching valve allows the lower part of the hot water storage tank to communicate with the inlet of the heat exchanger when power is applied at night, and the middle part of the hot water storage tank to communicate with the inlet of the heat exchanger when power is applied during the day. When electricity is supplied during the day, which is expensive, only the water in the upper part of the hot water storage tank can be circulated and heated, making it possible to heat the water efficiently and reduce power consumption, making it economical. In addition, only one heater and its control circuit are needed, which makes it cheaper.Furthermore, a large amount of water can be heated using inexpensive late-night electricity that is supplied to the heater, and hot water is used when electricity is supplied to the heater during the day. In addition to being limited to specific times and not requiring constant power supply,
It is possible to suppress an increase in the contracted current capacity of a general household power supply as daytime power used together with late-night power, and it is possible to use an electric water heater economically with a small contracted current capacity.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the electric water heater of the present invention when power is applied during the night, and FIG. 2 is an explanatory diagram when the electric water heater is energized during the daytime. 1... Hot water storage tank, 2... Water supply pipe, 3... Hot water outlet pipe, 4... Heat exchanger, 4a... Outlet, 4b...
Inflow port, 5... Heater, 6... Circulation pipe, 7... Circulation pipe, 8... Switching valve, 9... Circulation pipe, 10... Circulation pipe.

Claims (1)

[Scope of Claims] 1. A hot water storage tank with a water supply pipe connected to the bottom and a hot water outlet pipe connected to the top, a built-in heater installed outside the hot water storage tank for both nighttime power and daytime power, and an inlet and a hot water tank. a heat exchanger having an outlet, the outlet of the heat exchanger is connected to the upper part of the hot water storage tank via a circulation pipe, and the inlet of the heat exchanger is connected to the lower part of the hot water storage tank. When electricity is applied at night, the lower part of the hot water storage tank is connected to the inlet of the heat exchanger, and when electricity is applied during the day, the middle part of the hot water storage tank is connected to the circulation pipe connected to the intermediate part of the hot water storage tank. An electric water heater characterized in that each of the water heaters is connected via a switching valve that communicates with an inlet of an exchanger.