JPH0218432Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention circulates and heats the hot water in the hot water circulation piping at appropriate times to maintain the appropriate temperature, so that when the hot water tap is opened, hot water at the appropriate temperature can be obtained immediately. This relates to a water heater.

(Prior Art) A conventional water heater of this kind has a circulation pump and a temperature detection means disposed in the middle of a hot water circulation piping provided between a water heater and a hot water tap, and detects the temperature by the temperature detection means. If the water temperature is lower than the set temperature, circulation heating starts, and when the set temperature is reached, it stops.

(Problem to be solved by the invention) In this conventional water heater, when the temperature detection means is arranged on the outgoing pipe side of the hot water circulation piping, after the circulation heating operation starts, the heating operation of the water heater will adjust the temperature to the appropriate temperature. When hot water heated to The circulating heating operation stops before sufficient hot water at the appropriate temperature is introduced, and as a result, the time it takes for the water temperature at the temperature detection position to drop below the set temperature again is short, and the circulating heating operation stops. This will be done frequently in short cycles.

On the other hand, if the temperature detection means is provided on the return pipe side, the temperature of the hot water on the return pipe side decreases during hot water dispensing, so when hot water stops dispensing, even though the outgoing pipe side is filled with warm water at an appropriate temperature, the return pipe side The system detects the low temperature of the hot water and starts the circulating heating operation at the same time as the hot water supply stops.If hot water is restarted immediately after the hot water supply stops, the hot water will be at an unstable temperature due to transient phenomena caused by changes in the temperature of the water entering the water heater. The problem arises that hot water is dispensed. For example, if the set temperature of the water heater is 40°C and the starting temperature of the circulating heating operation is 38°C, during hot water dispensing, cold water at, say, 5°C is introduced from the water supply source into the water heater, and hot water at 40°C is passed through the outgoing pipe. During this time, the temperature of the hot water on the return pipe side tends to drop. Immediately after hot water stops dispensing, if it detects that the water temperature on the return pipe side is 38°C or lower, it starts circulating heating operation, so in practice, circulating heating operation is often performed at the same time as hot water dispensing. Cold water at 5°C is introduced into the vessel during hot water dispensing, and hot water at 38°C is introduced from the return pipe at the same time as hot water stops being dispensed.
℃ cold water is introduced, and the hot water temperature control of the water heater cannot keep up with this rapid change in the incoming water temperature in a short period of time, resulting in large fluctuations in the outlet temperature.

In this way, in any conventional water heater of this type, the circulating heating operation is started and stopped based on the temperature detected by a single temperature detection means, so the frequency of starting and stopping the circulating heating operation is Water heaters and circulation pumps start and stop more frequently, resulting in a large loss of fuel and electricity, which has a negative impact on the durability of these devices. However, there was a problem in that it became temporarily unstable and was extremely inconvenient to use.

The purpose of the present invention is to solve these problems with conventional water heaters of this type, to regulate unnecessary circulating heating operations, and to stabilize the temperature of hot water when hot water is re-discharged immediately after hot-water dispensing is stopped.

(Means for solving the problem) In order to achieve this objective, the present invention has the following configuration. That is, a circulation pump is interposed in the middle of the hot water circulation piping installed between the water heater and the hot water tap, and the start and stop of the hot water circulation heating operation immediately after the hot water supply stops is controlled by separate control means. I try to control it.

(Example) An example of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of an embodiment of the present invention, in which 1 is a water heater, 2 is a hot water tap, and 3 is a hot water circulating device provided between the water heater 1 and the hot water tap 2. It is a pipe and consists of an outgoing pipe 4 and a return pipe 5.

A temperature detection means 6 is provided in the middle of the outgoing pipe 4, and a temperature detection means 7 and a circulation pump 8 are provided in the middle of the return pipe 5 in this order from the upstream side. 9 is a water supply pipe connected from the water supply source 10 between the temperature detection means 7 of the return pipe 5 and the circulation pump 8; 11 is a water flow detector provided in the water heater 1; 12 is a heat exchanger; 13 is a burner provided below the heat exchanger 12. In a water heater made of such members, the circulation heating operation is started based on the hot water temperature detected by the temperature detecting means 6 on the outgoing pipe 4 side, and the hot water temperature detected by the temperature detecting means 7 on the return pipe 5 side is started. The circulating heating operation is stopped based on the following.

Note that the temperature detection means 6, 7, circulation pump 8, etc. may be built into the exterior of the main body of the water heater 1.

The operation of one embodiment of the present invention having the above-mentioned configuration will be explained. FIG. 2 is an explanatory diagram showing a temperature change between the temperature t1 detected by the temperature detection means 6 provided on the outgoing pipe 4 and the temperature t2 detected by the temperature detection means 7 provided on the return pipe 5.

If the hot water tap 2 is opened while the hot water in the hot water circulation pipe 3 is being maintained at an appropriate temperature, the hot water at the appropriate temperature in the outgoing pipe 4 will be immediately discharged, and the amount of water that has been dispensed will be is drawn from the water supply source 10 through the water supply pipe 9 to the suction side of the circulation pump 8 of the return pipe 5, heated to an appropriate temperature by the water heater 1, and sent to the hot water tap 2. During this time, the hot water in the return pipe 5 comes into contact with the cold water introduced from the water supply pipe 9, and the temperature t2 detected by the temperature detection means 7 decreases as shown in FIG. When the hot water tap 2 is closed and the hot water supply is stopped, the detected temperature t2 is lower than the circulating heating start temperature.
However, at this time, the outgoing pipe 4 is filled with warm water at an appropriate temperature, and in this embodiment, the circulation heating operation is started based on the detected temperature t1 on the outgoing pipe 4 side. The circulating heating operation does not start until the detected temperature t1 on the pipe 4 side falls below the circulating heating start temperature, and the water heater 1 remains at the setting at the time of hot water dispensing, that is, the cold water supplied from the water supply source 10 is Since the amount of heating is set to raise the temperature to the set temperature, when hot water is restarted immediately after hot water is stopped, the hot water at the appropriate temperature in the outgoing pipe 4 is immediately tapped, and the water heater 1 receives water from the water supply source 10. The supplied cold water is quickly heated to the set temperature, and a stable hot water temperature can be obtained. In addition, since the circulation heating operation is stopped based on the detected temperature t2 on the return pipe 5 side, it is stopped after both the outgoing pipe 4 and the return pipe 5 are filled with hot water at an appropriate temperature, and therefore the hot water circulation piping The temperature difference within the hot water circulation pipe 3 is almost eliminated, no natural convection occurs within the hot water circulation pipe 3, the detected temperature t1 becomes stable, and the time interval until the next circulation heating operation is performed is made as long as possible. be able to.

FIG. 3 shows a schematic configuration of another embodiment of the present invention, and the same numbers as in FIG. 1 indicate the same members. Reference numeral 14 denotes a time control means, which prevents the circulation pump 8 from operating for a certain period of time after the water flow detector 11 changes from on to off.
Even during this certain period of time, if the water flow detector 11 is turned on again, the above control is canceled.

When hot water is stopped in the embodiment shown in FIG. 3, the hot water in the return pipe 5 is at a low temperature as described above, but the hot water in the outgoing pipe 4 remains at an appropriate temperature for a while. During this time, time limit control means 1
4 prevents the cyclic heating operation from starting.
That is, the water flow detector 11 is turned off when hot water is stopped, and the time control means 14 is activated to prevent the circulation pump 8 from operating for a certain period of time. If hot water is re-discharged during this period, the water flow detector 11 is turned on, and this control is canceled and hot water at an appropriate temperature in the outgoing pipe 4 is dispensed, while cold water supplied from the water supply source 10 is brought to an appropriate temperature in the water heater 1. It is heated and then released.

Note that, except for a certain period of time immediately after the hot water tap is stopped, the circulating heating operation is started and stopped based on the temperature detected by the temperature detecting means 7.

By doing this, the embodiment shown in Fig. 3 can achieve the same effect as the embodiment shown in Fig. 1, which prevents unnecessary circulation heating and stabilizes the water supply when re-dispensing immediately after dispensing. This allows you to tap the hot water at a certain temperature.

(Effects of the invention) The invention has the following excellent effects. In other words, in addition to regulating unnecessary circulating heating operations to prevent the resulting loss of fuel and electricity and reducing the durability of the equipment, it is also possible to prevent circulating heating operations from starting immediately after hot water taps have stopped, and thereby prevent restarting immediately after hot water taps have stopped. It is possible to prevent sudden changes in the temperature of water entering the water heater when hot water is being discharged, and the temperature of the discharged water can be stabilized.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention;
FIG. 2 is an explanatory diagram showing changes in detected temperature in the embodiment of FIG. 1, and FIG. 3 is a schematic diagram showing another embodiment of the present invention. 1...Water heater, 3...Hot water circulation piping, 4...
Outgoing pipe, 5... Return pipe, 6, 7... Temperature detection means,
8... Circulation pump, 10... Water supply source, 11... Water flow detector, 14... Time control means.

Claims (1)

[Scope of utility model registration request] In a water heater in which a circulation pump is interposed in the middle of hot water circulation piping provided between a water heater and a hot water tap, separate control means are provided for starting and stopping a circulating heating operation of hot water immediately after stopping hot water dispensing. A water heater characterized in that it is controlled by.