JPS6015057Y2 - electric water heater - Google Patents

Description

[Detailed explanation of the invention] An electric water heater has a structure in which an electric heater, a heat storage tank, a control circuit, etc. are integrated. Conventionally, the material of the heat storage tank is a corrosion-resistant glass-lined steel plate or stainless steel plate. However, if pitting corrosion occurs and a water leakage occurs, the entire electric water heater will have to be replaced, so to prevent this, sacrificial electrodes or galvanic corrosion protection are also used to ensure completeness. There is.

This increases costs, and requires inspection of sacrificial electrodes.
Galvanic corrosion protection requires care to ensure that current is constantly flowing, which has been a problem.

On the other hand, in recent years, advances in heat-resistant resins have resulted in resins that can withstand boiling temperatures sufficiently, and these resins tend to be widely used in solar water heaters.

In view of the above points, the present invention is based on the idea of separately providing a heat storage tank and an electric heater in an electric water heater, and using a heat-resistant resin as described above for the heat storage tank. Because of its inherently excellent corrosion resistance, it eliminates the need for sacrificial anodes or galvanic corrosion protection, thus providing an inexpensive and long-life electric water heater.

The reason why the heat storage tank and electric heater are separated is that even heat-resistant resin has lower heat resistance than conventional metal materials, so if the heater is housed in this resin heat storage tank, the part of the heat storage tank where the heater is attached will be exposed to heat. This is to avoid the problem of loosening the tool and causing water leakage due to the softening and the difference in expansion rates between the two.

In addition, resin heat storage tanks have relatively weak pressure resistance and are not strong enough to withstand the high water pressure of tap water, so a device is installed on the water supply side of the heat storage tank to lower the tap water to atmospheric pressure. Although it is necessary to specially install a pump to supply the desired hot water pressure to the hot water supply side, even if the cost for this is taken into consideration, the electric water heater as a whole is economically advantageous.

The details of the specific structure will be described with reference to the drawings.

First, in the conventional electric water heater shown in Fig. 1, the heat storage tank 1
' is made of a steel plate or stainless steel with a glass lining on the inner surface, and an electric heater 2 is installed on the lower inside thereof.

The above-mentioned glass-lined steel plate is prone to pinholes, etc. on the glass lining surface, and stainless steel plates have residual stress in the welded area between the main body and the top cover plate, and these pinholes or welded areas are likely to cause corrosion. To prevent this, a sacrificial anode 3 is installed hanging down from the top surface of the tank into the tank.

Its material is Mg rod.

A casing 5 surrounding the heat storage tank 1' is provided outside the heat storage tank 1', and a heat insulating material 6' such as glass wool is filled between them.

A water supply inlet 1a' is provided at the bottom of the tank 1', to which tap water is supplied from a water supply pipe 15 via a pressure reducing valve 7.

A pressure regulating valve 8 is provided branching off from between the inlet la' and the valve 7, and its outlet leads to a drain 18.

A hot water supply outlet 1b' is provided at the center of the top surface of the tank 1, and this is led out to a hot water supply appliance 17 via a hot water supply pipe 16.
It branches off from directly above ' and is led out to the drain 18 via the safety valve 9.

Also installed within the casing 5 is a control circuit 4 .

When using the above sacrificial anode 3 in tap water with average water quality, 6~
It needs to be replaced every 8 years, and in places with poor water quality it will take 2-3 years.
Situations may occur that require replacement every year.

Furthermore, when galvanic corrosion protection is used, there have been accidents where pitting corrosion occurred in the tank because the heat storage tank was installed in an apartment building and the power circuit was turned off until the apartment moved in.

Next, in one embodiment of the present invention shown in FIG.
is molded from a heat-resistant resin such as ethylene resin or polypropylene resin, and its heat resistance is up to a boiling water temperature of 85°
It can withstand temperatures of approximately C±5°C, and its corrosion resistance is also sufficiently high.

Water ball tap 1 following the water supply port 1a on the upper left of tank 1
0 is provided to prevent water pressure from being applied to the tank 1.

That is, when the ball floating on the water surface in the tank is below a predetermined level, the inner end of the water supply port is opened to introduce water, and when the predetermined level is reached, the outlet is closed, thereby maintaining the water surface level at a constant level. At the same time, the water pressure at the water surface in the tank is always maintained at atmospheric pressure regardless of the water supply pressure.

In the casing 5, a heater tube 12 is provided on the right side separately from the tank 1, and an electric heater 2 is housed in the heater tube 12.

In addition to the hot water inlet 1b, there are two openings 1d and 1 on the right side wall of the tank 1.
e is cut out, and these are communicated with two openings provided on the upper and lower left side of the heater tube 12 through a heat-resistant flexible tube 13.

The heater tube 12 is made of a corrosion-resistant metal such as stainless steel, and its wall thickness is appropriately selected depending on the degree of corrosion that actually exists.

The visible tube 13 is made of heat-resistant rubber, such as butyl rubber, for example.

In the second illustrated embodiment, there is natural convection inside the heater tube 12, so in order to improve the effect, a thick flexible tube 13 is used, and its diameter is about 5 mm.

The hot water supply port 1b is led out to a hot water supply device 17 in the same manner as in FIG. 1, but a pump 14 for applying water pressure for hot water supply is inserted in the middle thereof.

That is, in FIG. 1, the water pressure in the water supply pipe 15 is appropriately high, so when the water heater 17 is opened, hot water is automatically supplied using only that water pressure, but in FIG. 2, the pressure at the water surface of the tank 1 is atmospheric pressure. Since it is not possible to supply hot water satisfactorily with this alone, a pump 14 is installed to reinforce this.

A control circuit 4 installed within the casing 5 is connected to an external remote controller 19.

That is, the gauging 5 including the heat storage tank is usually installed outdoors in many cases, whereas it is convenient to install the operating device 19 indoors, so they are connected by an electric wire.

The control circuit 4 controls the starting of the pump 14 and the water heater 17.
Hot water can be supplied immediately by opening the pump, or if the appliance 17 is previously opened, hot water can be supplied immediately by starting the pump 14.

Note that a water conduit 11 is provided in association with the pole tap 10.

This hangs down from directly below the water supply port 1a, and its lower end reaches the bottom of the tank 1, and its purpose is to introduce the cold water to be supplied into the bottom of the tank to avoid mixing of cold water and hot water.

For the same purpose, a plate for separating the left and right sides may be used instead of the tube 11.

In order to prevent the tank 1 from deforming due to the weight of the water contained therein, the heat insulating material 6 surrounding the tank 1 is made of a hard resin such as hard polyurethane, which is different from the soft resin 6' shown in FIG. Ru.

In Fig. 2, the heater 2 starts operating in response to the signal when the midnight power period starts, and the cold water in the tank 1 is supplied to the opening 1e.
The water enters the heater tube 12 through the heater tube 12, and the water heated by the heater 2 enters the tank 1 through the opening 1d by natural convection.

When the entire water in the tank reaches a predetermined temperature, the heater 2 is de-energized by the operation of the thermostat.

Thereafter, when the control circuit 4 is activated by the remote controller 19, the pump 14 is activated and starts supplying hot water.

As a result, when the water in the tank decreases, the reduced amount is automatically replenished from the water supply port 1a by operating the pole tap 10.

If pitting occurs in the heater tube 12 due to long-term use and water leaks, only this heater tube can be replaced and the tank 1 can be used as is.

This replacement is extremely simple and inexpensive compared to replacing the large tank 1 shown in FIG. 1 due to corrosion.

In another embodiment shown in FIG. 3, the pump 14 is repositioned and inserted into the waterway of the heater tube 12, and the series waterway between the tube 12 and the pump 14 is connected between the openings 1b and 1e of the tank 1. Ru.

The other configurations are generally the same as in FIG. 2.

In FIG. 3, the water flow in the pipe 12 is forced through by the pump 14, so the water flow can be made appropriately fast, and the upper and lower flexible pipes 13 have smaller diameters than in the case of FIG. For example, about 2 pieces are often used.

Pump 14 is set to start at the same time heater 12 is energized.

As a result of these operations, the water in the tank 1 reaches a predetermined temperature, and hot water is supplied by opening the post hot water supply device 17.

In this case, in order to allow most of the hot water coming out of the pump 14 to go toward the appliance 17, the flexible tube 13 on the opening 1b side should be made an appropriately small diameter tube to increase its water flow resistance. This is desirable.

In the configuration of FIG. 2, it is also possible to remove only the heater tube 12 and replace it with another heat source, such as an oil or gas water heater.

According to the present invention, by using a heat-resistant resin with excellent corrosion resistance as the material of the heat storage tank, it is possible to provide an inexpensive electric water heater that does not require sacrificial anodes or galvanic corrosion protection.

[Brief explanation of drawings]

FIG. 1 is a schematic elevational view showing a conventional electric water heater, FIG. 2 is a schematic elevational view showing an electric water heater according to the present invention, and FIG. 3 is a schematic elevational view showing a variation thereof. 1: Heat storage tank, 2: Electric heater 12: Heater tube, 1
4: Hot water pump.

Claims (1)

[Scope of utility model registration request] The heat storage tank of the electric water heater is made of heat-resistant resin, the electric heater is housed in a corrosion-resistant metal pipe that is installed separately from the heat storage tank and communicates with it, and the high tap water pressure in the heat storage tank is lowered to atmospheric pressure. An electric water heater that is equipped with a pole tap type water supply device and a pump for reinforcing hot water pressure on the hot water supply side.