JPH0343543B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a water heater.

(Conventional technology) Conventionally, hot water in the pipe leading from the water heater to the hot water faucet becomes cold water due to heat radiation, and in view of the problem that cold water is discharged for a while even when the hot water faucet is opened, hot water does not come out easily. , a system has been proposed in which a circulation path is formed between a water heater and a hot water faucet to maintain heat and circulate the water.

For example, Japanese Patent Application Laid-open No. 60-233445 discloses a system that detects the temperature of hot water in the circulation path and the circulation flow rate, calculates the amount of heat required to heat the water to a set temperature, and intermittently burns the water heater. is shown.

(Problems to be Solved by the Invention) However, in this conventional system, ignition and extinguishing operations of the water heater are frequently performed, and there is a problem in that the durability of the fuel valve is disadvantageous. In other words, the amount of heat required during heat-retaining circulation is in most cases much smaller than that during normal hot water supply, and during heat-retaining circulation, ignition and extinguishing are frequently performed in extremely short cycles.

Another option is to use a water heater that can vary the amount of combustion and heat the water at the lowest amount of combustion until the set temperature is detected, but if the difference between the temperature at which heating starts and the set temperature is small, it will still take a while after ignition. Since the fire will be extinguished in a short time and the water heater will end up being turned on and off frequently, there is a problem that the warming operation start temperature must be set at a temperature considerably lower than the set temperature, which is inconvenient to use.

In any case, the higher the capacity of the water heater, the more frequent the flashing to keep the water warm, and the more likely the water temperature is to overshoot.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to provide a water heater that can reduce the number of flickerings of the water heater, and can accurately control the water temperature in a heat-retaining cycle where overshoot of the water temperature is less likely to occur.

(Means for Solving the Problems) In order to achieve the above object, the present invention has the following configuration. That is, it includes an outgoing pipe leading from the hot water outlet pipe of the water heater to the hot water tap, and a return pipe connecting from the outgoing pipe near the hot water tap to the water supply pipe of the water heater, and a circulation pump is provided in the middle of the return pipe. In a device that forms a circulation path between a water heater and a hot water tap, a hot water storage tank equipped with an electric heater and a temperature sensor are provided at appropriate locations in the circulation path, and the water temperature detected by the temperature sensor is set to the set temperature. When the water temperature is lower than the set temperature, the electric heater is activated, and when the water temperature is lower than the set temperature and the deviation is above a certain value, the water heater starts combustion, and the combustion is stopped before the water temperature reaches the set temperature. The hot water in the circulation path is kept warm.

(Function) When the temperature of the water in the circulation path is lower than the set temperature, the temperature of the water in the circulation path is kept close to the set temperature by appropriately selecting between heating by the electric heater and heating by combustion in the water heater. For example, the hot water in the circulation path is circulated at the beginning of operation and after the hot water supply is stopped, and if the hot water temperature is lower than the set temperature, it is heated by an electric heater. However, if the deviation between the water temperature and the set temperature exceeds a certain value, in addition to heating the electric heater, the water heater is combusted to rapidly heat the water, and when the deviation becomes small to a certain extent, combustion is stopped. let Thereafter, it is heated to the set temperature using an electric heater. Therefore, when the deviation is small, the water heater is not combusted, the number of blinks of the water heater is avoided to be increased unnecessarily, and the water is gradually heated only by the electric heater, so that overshoot of the water temperature is less likely to occur. If the deviation is large, the water is heated rapidly by combustion in the water heater, and the combustion is stopped before the set temperature is reached, and then the electric heater is used to heat the water, making it difficult to overshoot the water temperature. .

(Example) In FIG. 1, 1 is a main body of a water heater, which has a first water heater 2 and a second water heater 3 built therein. The first and second water heaters 2 and 3 are connected in a closed line and are supplied with water from a common water supply pipe 4. 5 is an outgoing pipe leading to the hot water tap 6; 7 is a return pipe connecting from the hot water tap 6 to the middle of the water supply pipe 4; the return pipe 7 is equipped with a check valve 8, a circulation pump 9, and an electric heater 10; A tank 11 is provided. Reference numeral 12 denotes a bypass pipe that branches off from the middle of the water supply pipe 4 and connects to the outgoing pipe 5, and has a flow rate regulator 13 equipped with an electric drive means in the middle. Reference numeral 14 denotes a temperature detector provided downstream from the junction of the outgoing pipe 5 with the bypass pipe 12.
Reference numeral 15 designates a water supply pipe, a water flow sensor provided downstream of the branch point with the bypass pipe 12 of 4 and upstream of the confluence with the return pipe 7, and 16 and 17 each designate a check valve.

In this embodiment, the first and second water heaters 2 and 3 have water flow rate sensors 22 and 32 and temperature detectors 23 and 32, respectively, provided on the water inlet sides of heat exchangers 21 and 31.
The amount of heating is calculated based on the amount of incoming water and the incoming water temperature detected by 33, and a set temperature TS of a remote controller (not shown), and the amount of combustion of the burners 24 and 34 is controlled. In addition, flow rate regulators 25 and 3 are provided, respectively.
5, and automatically adjusts the amount of water flow according to the set temperature (TS2) and (TS3) of each water heater 2 and 3 so as not to exceed the maximum capacity that can control the water supply temperature by the amount of combustion. That's what I do. However, the flow rate regulator 35 of the second water heater 3 is the water flow rate sensor 15.
When the detected flow rate is less than a predetermined flow rate, it is controlled to the fully closed position, and when it is more than the predetermined flow rate, it is controlled to a position according to the set temperature (TS3) of the water heater as described above.

The operation of the water heater having such a configuration will be explained. When the operation switch (not shown) is turned on for the first time, if the hot water tap 6 is closed, the water supply pipe 4
Since water is not supplied from the tank, the water flow sensor 15 does not detect the flow, and in this case, the electric heater 10 is powered on and the circulation pump 9 is energized. Since the flow rate regulator 35 is controlled to the fully closed position when the flow rate detected by the water flow sensor 15 is less than a predetermined flow rate (for example, 5/min), hot water flows only to the first water heater 2. Therefore, the first water heater 2,
Hot water is circulated in a circulation circuit consisting of an outgoing pipe 5, a return pipe 7, etc., and a temperature detector 14 provided in the middle of the outgoing pipe 5 detects the temperature of the circulating water. If the detected temperature is lower than the set temperature (TS) of the remote control, and if the temperature deviation is greater than the first deviation (for example, 15 degrees), the first water heater 2
burner 24 is fired. Therefore, the circulating hot water is heated by the electric heater 10 and the first water heater 2. As a result, when the deviation between the temperature detected by the temperature detector 14 and the set temperature becomes equal to or less than a second deviation (for example, 12 degrees), combustion in the burner 24 is stopped, and heating is thereafter performed only by the electric heater 10. and temperature sensor 1
4 detects a temperature equal to or higher than the set temperature (TS), power supply to the electric heater 10 is stopped. Further, if the temperature continues to be detected at the set temperature (TS) or higher for a certain period of time, the circulation pump 9 is also stopped. In addition, if the deviation between the first detected temperature and the set temperature (TS) is within the first deviation (15 degrees), the burner 24 is not fired, heating is performed only by the electric heater 10, and the following settings are made in the same manner. When the temperature (TS) or higher is detected, heating by the electric heater 10 is stopped, and when the temperature exceeds the set temperature (TS) for a certain period of time, the circulation pump 9 is stopped. Also,
If the first detected temperature is already equal to or higher than the set temperature (TS), the electricity supply to the electric heater 10 is stopped, and if the temperature continues to be detected at the set temperature (TS) or higher for the predetermined period of time, the circulation pump 9 is also stopped.

Now, the hot water in the circulation circuit will eventually cool down due to natural cooling, but when the temperature detected by the temperature detector 14 falls by a certain temperature (for example, 3 degrees) or more below the set temperature (TS), the hot water circulation operation will resume. That is, the electric heater 10 is energized, the circulation pump 9 is energized, and the operation is resumed as described above.

Next, the action during hot water supply will be explained. When the hot water tap 6 is opened, water is supplied from the water supply pipe 4 and the water quantity sensor 1
5 detects this, and if the heat-retaining circulation operation is in progress, the electric heater 10 and the circulation pump 9 are de-energized. When the water amount sensor 22 of the first water heater 2 detects a minimum operating water amount (2/min) or more, heating starts. Here, the set temperature (TS2) of the first water heater 2 is set to a higher temperature than the set temperature (TS) of the remote controller. That is, TS2=TS+α, where α is set in advance according to the flow rate of the water flow sensor 22. On the other hand, the flow rate regulator 13 provided in the bypass pipe 12 adjusts the set temperature (TS) of the remote control.
controlled with the goal of Therefore, the high temperature (TS2) hot water heated by the first water heater 2 and the bypass pipe 1
2 is mixed with the water supplied from temperature sensor 1.
The flow rate regulator 13 adjusts the amount of water based on the detected temperature in step 4, and mixed hot water at a set temperature (TS) is supplied.

When supplying a large amount of hot water, that is, water flow sensor 1
When the flow rate of water heater 5 becomes equal to or higher than a predetermined flow rate (5/min), the flow rate regulator 35, which had been controlled to the fully closed position, is opened, and water is also supplied to the second water heater 3. Similarly to the first water heater 2, the second water heater 3 is heated to a set temperature (TS3) higher than the set temperature on the remote controller. The hot water heated by the first and second water heaters 2 and 3 is mixed with water from the bypass pipe 12 and supplied.

When the hot water tap 6 is closed, the water flow sensor 15 detects that the water supply has stopped, and the system returns to its initial state. That is, when the electric heater 10 is powered on, the circulation pump 9 is energized and the temperature of the circulating water is detected, and as a result, if necessary, a warming operation is performed.

(Effects of the Invention) The present invention has the following excellent effects. In other words, the water in the pipe between the water heater and the hot water faucet can be kept close to the set temperature, the water heater can be prevented from blinking unnecessarily to keep it warm, and the circulating water temperature can be kept at the same temperature as the set temperature. When the deviation from the temperature becomes smaller, the electric heater heats the water relatively slowly, which reduces the variation in the water temperature in the circulation path and makes it difficult for overshoots to occur in the water temperature.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention. 1... Water heater main body, 2... First water heater, 3
...Second water heater, 4...Water supply pipe, 5...Outgoing pipe,
6...Hot water tap, 7...Return pipe, 9...Circulation pump,
10...Electric heater, 11...Hot water storage tank.

Claims (1)

[Claims] 1.Equipped with an outgoing pipe leading from the hot water outlet pipe of the water heater to the hot water supply tap, and a return pipe connected from the outgoing pipe near the hot water tap to the water supply pipe of the water heater, and a circulation pump is installed in the middle of the return pipe to supply hot water. In a device that forms a circulation path between a boiler and a hot water tap, a hot water storage tank equipped with an electric heater and a temperature sensor are installed at appropriate locations in the circulation path, and the water temperature detected by the temperature sensor is lower than the set temperature. When the water temperature is low, the electric heater is activated, and when the water temperature is lower than a set temperature and the deviation thereof is above a certain value, combustion is started in the water heater, and combustion is stopped before the water temperature reaches the set temperature. A water heater characterized by keeping hot water in a circulation path warm.