JPH0419454B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a gas instantaneous hot water supply system that uses a burner to perform intermittent combustion when the required amount of heat is small.

(Prior Art) Prior to filing this application, the applicant had proposed the following gas instantaneous water heater.

This hot water supply system connects a return pipe equipped with a pump between a hot water supply pipe that connects a heat exchanger outlet to a hot water supply equipment and a water supply pipe that connects a heat exchanger inlet to a water supply source. In this method, water is circulated through a circulation system path consisting of the heat exchanger outlet, hot water supply pipe, return pipe, water supply pipe, and heat exchanger inlet, and the circulating water is burned and extinguished within a predetermined time. A predetermined temperature is maintained by a burner that controls the amount of heat based on the ratio of repeated combustion time to extinguishing time.

(Problem to be Solved by the Invention) However, in the above water heater, the cycle of combustion and extinguishing of the burner does not change between when supplying hot water and when supplying hot water is stopped, and the combustion time and extinguishing time within a certain cycle are not changed. The temperature of the hot water supply and the temperature of the circulating water are maintained at a predetermined temperature by changing the ratio of As the temperature decreases, the combustion time of the burner becomes shorter and the extinguishing time becomes longer, which may result in increased hunting in the hot water supply temperature.

As a means to reduce such hunting in the hot water supply temperature when a small amount of hot water is supplied, it is conceivable to change the cycle of combustion and extinguishing of the burner between when hot water is being supplied and when the hot water supply is stopped.

For example, during hot water supply, short cycles (for example, 5
This system aims to reduce hunting in the hot water temperature by causing the burner to burn and extinguish in a long cycle (for example, 30 seconds) when hot water supply is stopped.

However, conventional water heaters have a configuration in which a water flow sensor detects the amount of water flowing through the pipes, and this detects whether hot water is being supplied or not.
When the amount of hot water supplied and the amount of circulating water become approximately equal, it is impossible to distinguish between the hot water supply state and the hot water supply stopped state.

For this reason, the cycle of combustion and extinguishing of the burner cannot be appropriately set according to each state of hot water supply and hot water supply stop, and there is still a risk that problems such as increased hunting of the hot water supply temperature may occur.

Furthermore, if the number of times the burner burns and extinguishes is increased more than necessary, there is a risk that the durability of the burner will decrease.

This invention was made to solve these problems, and it is possible to reliably detect the hot water supply state and the hot water supply stop state using factors other than the amount of water, and to appropriately set the combustion and extinguishing cycle of the burner according to each state. The purpose of this is to reduce hunting in the hot water supply temperature, and to improve the durability of the burner by reducing the number of times the burner is turned on and off by setting the control cycle for combustion and extinguishing to be longer during circulation operation. do.

(Means for Solving the Problems) In order to solve the above problems, a gas instantaneous water heater according to the present invention includes a hot water supply pipe connecting a heat exchanger outlet to a hot water supply appliance and a hot water supply pipe connecting the heat exchanger inlet to a water supply source. A return pipe equipped with a pump is connected between the water supply pipe and the return pipe to form a circulation system, and the flow of water on the upstream side of the connection with the return pipe of the water supply pipe allows hot water to be supplied and stopped. A water flow sensor is installed to detect the time, and when the required amount of heat is less than a predetermined amount of heat, combustion occurs intermittently by repeating combustion and extinguishing at different cycles during hot water supply and when hot water supply is stopped. A small-capacity burner that heats the heat exchanger by continuous combustion to maintain the hot water supply temperature at a predetermined temperature when the required amount of heat exceeds a predetermined amount of heat; It is characterized by being equipped with a large-capacity burner that maintains the hot water supply temperature at a predetermined temperature by continuously heating the heat exchanger.

(Function) A water flow sensor that detects water flow is installed upstream of the connection between the water supply pipe and the return pipe, so based on the detection output of this water flow sensor, when water flow is detected, the hot water supply state is determined. When no water flow is detected, it can be determined that the hot water supply is stopped using the circulation system.

Therefore, even when intermittent combustion is performed using a small-capacity burner with a relatively small required amount of heat, the period of intermittent combustion is set to a different value between the hot water supply state and the state where hot water supply is stopped and circulating heat retention is performed. This reduces hunting in hot water temperature and
During circulation operation, by setting the combustion and extinguishing control period to be long, the number of times the burner is turned on and off can be reduced, and the burner resistance to penetration can be improved.

In addition, it is equipped with a small-capacity burner and a large-capacity burner, and if the amount of heat is insufficient even if the small-capacity burner is continuously burned, the large-capacity burner is continuously burned, so even if the required heat amount is over a wide range, the hot water supply temperature and circulation can be adjusted. The insulating temperature of water can be stably controlled.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a heat exchanger, 2 is a hot water supply pipe connecting the outlet of the heat exchanger to a hot water supply device 3 such as a faucet, and 4
5 is a water supply pipe connecting the heat exchanger inlet to a water supply source;
a is a small capacity burner, 5b is a large capacity burner, 6a and 6b are proportional control valves and solenoid valves provided in the gas pipe 7a of the small capacity burner 5a, 8
a, 8b are gas pipes 7b of large capacity burner 5b
a proportional control valve and a solenoid valve provided in the control board;
4 is a former solenoid valve.

On the upstream side of the hot water supply pipe 2, there is provided a hot water temperature sensor 10 for detecting the temperature of hot water coming from the heat exchanger 1. In addition, the hot water supply pipe 2 is connected to the hot water supply equipment 3 on the downstream side.
It is branched into a side and a return pipe 11 side.

The return pipe 11 is equipped with a pump P, and the downstream side of the pump P is connected to the midway part of the water supply pipe 4 to connect the hot water supply pipe 2 and the water supply pipe 4 via the return pipe 11. This constitutes a circulation path through which water is circulated to keep it warm when hot water supply is stopped.

In addition, the pump P that circulates water is operated at a rate of 2 per minute so as not to disturb the supply of hot water to the water heater 3 even if it is operated during hot water supply.
I use one with a small capacity, about the size of a liter. The control board 9 continuously operates the pump P based on the pump drive signal D.

Note that the control board 9 may operate the pump P only when determining that the hot water supply is stopped based on the water flow detection output of the water flow sensor S, which will be described later.

In addition, the water supply pipe 4 is connected to the water supply pipe 4 from the upstream side.
a water amount sensor 12 that detects the amount of water flowing through the heat exchanger 1, and an inlet water temperature sensor 1 that detects the temperature of water entering the heat exchanger 1.
3 are provided.

The control board 9 is electrically connected to each solenoid valve 6b, 8b, each proportional control valve 6a, 8a, outlet water temperature sensor 10, pump P, water flow sensor 12, and inlet water temperature sensor 13, and sends a signal D to the pump P. While transmitting and driving the same pump P, each sensor 10,1
The system is configured to receive signals A, B, and C from 2 and 13 to calculate the required amount of heat during hot water supply and when hot water supply is stopped to keep water warm.

The control board 9 calculates the temperature difference between the outlet water temperature and the inlet water temperature from the outlet water temperature detected by the outlet water temperature sensor 10 and the inlet water temperature detected by the inlet water temperature sensor 13, and calculates the temperature difference between the outlet water temperature and the inlet water temperature, and uses the flow rate sensor 12 to detect this temperature difference. The required amount of heat is calculated by multiplying the calculated flow rate.

Then, the control board 9 controls the small-capacity burner 5a based on the required amount of heat determined by calculation.
The configuration is such that the burner 5b with a large capacity is selected.

In addition, when the small capacity burner 5a is selected, the control board 9 sends a pulse signal E to the solenoid valve for the small capacity burner 5a at a pulse interval corresponding to the required heat quantity when the required heat quantity is less than a predetermined heat quantity. 6b. In this case, the pulse interval of the pulse signal E is set to be different when hot water is being supplied and when hot water is being stopped, and is set to be short in the former case and long in the latter case.

Further, the solenoid valve 6b receives the pulse signal E from the control board 9, and repeats opening and closing based on the length and interval of the pulse, thereby intermittently supplying gas to the burner 5a. Therefore, the small capacity burner 5a
is the pulse signal E during hot water supply and when hot water supply is stopped, respectively.
The heat exchanger 1 is controlled to be heated intermittently by repeating combustion and extinguishing at different cycles based on the length and interval of the pulses, for example, 5 seconds when hot water is being supplied and 30 seconds when hot water is stopped.

Furthermore, the control board 9 includes a small capacity burner 5a.
When the required amount of heat exceeds a preset predetermined amount of heat in the case where the required amount of heat is selected, the valve opening signal E is supplied to the electromagnetic valve 6b, and the amount of gas corresponding to the required amount of heat is supplied to the burner 5 during hot water supply and when hot water supply is stopped.
Continuously supply to a. Therefore, the small-capacity burner 5a continuously burns with the required amount of heat during hot water supply, and heats the heat exchanger 1.

On the other hand, when the large capacity burner 5b is selected, the control board 9 controls the solenoid valve 8 for the large capacity burner 5b.
In addition to supplying the valve opening signal G to the large-capacity burner 5b, an electric signal H corresponding to the amount of heat required for hot water supply is supplied to the large-capacity burner 5b.
The heat exchanger 1 is continuously heated while controlling the amount of gas supplied to the proportional control valve 8a.

Further, a water flow sensor S that detects when hot water is being supplied and when hot water is being stopped is disposed upstream of the connection part of the water supply pipe 4 with the return pipe 11, and is arranged on the upstream side of the connection part of the water supply pipe 4 with the return pipe 11, and is connected to the water flow sensor S from the water supply source to the heat exchanger 1 during hot water supply. It is activated by sensing the flow of water and sends a signal to the control panel 9. That is, the control board 9 determines the hot water supply state and the hot water supply stop state based on the presence or absence of a signal from the water flow sensor S.

Next, the operation will be explained.

The control board 9 calculates and determines the required amount of heat based on the detection signals A, B, and C from the hot water outlet temperature sensor 10, the water flow rate sensor 12, and the inlet water temperature sensor 13,
If the calculated required amount of heat is less than or equal to the predetermined amount of heat, the small capacity burner 5a is selected, and if the calculated required amount of heat exceeds the predetermined amount of heat, the large capacity burner 5b is selected.

When hot water is supplied, that is, when hot water is used by the hot water supply device 3, water is supplied from the water supply source to the heat exchanger 1, and the water flow sensor S detects the supply of this water.

The control board 9 receives the signal from the water flow sensor S, determines whether the hot water supply is in the hot water supply state or the hot water supply stopped state, and selects each burner 5 according to the state.
Control the amount of gas in a and 5b.

FIG. 2 is a flowchart showing an example of control of this water heater.

Note that ST1 to ST11 in FIG. 2 indicate each step of the flowchart.

The control board 9 determines whether the water supply is in the hot water supply state or the hot water supply is stopped based on the water flow detection output of the water flow sensor S (ST1).

If no water flow detection output is obtained from the water flow sensor S, the control board 9 determines that hot water supply is not in use (hot water supply stopped state) (ST2).

The control board 9 calculates the required amount of heat by multiplying the temperature difference between the outlet water temperature and the inlet water temperature by the flow rate (corresponding to the circulation flow rate) (ST3), and also turns on the small-capacity burner 5a since the hot water supply is not in use. Select (ST4).

Then, the combustion time and extinguishing time are allocated within the intermittent cycle (for example, 30 second cycle) in the hot water supply stop state based on the calculated required heat amount, and the small capacity burner 5a is caused to perform intermittent combustion (ST5).

If a water flow detection output is obtained in step 1, the control board 9 determines that hot water is being supplied (ST6), and calculates the required amount of heat (ST7).

The control board 9 compares the calculated required amount of heat with a predetermined amount of heat, and if the required amount of heat is less than the predetermined amount of heat, the control board 9 selects the small capacity burner 5a (ST8).

When the small capacity burner 5a is selected and the required amount of heat is relatively small, intermittent combustion control of the small capacity burner 5a is performed by controlling the opening and closing of the solenoid valve 6b (ST9), and when the required amount of heat is relatively large, the small capacity burner 5a is controlled to open and close. While continuously burning the capacity burner 5a, the proportional control valve 6
The amount of gas supplied to the small capacity burner 5a is adjusted by controlling the opening degree of a (ST10).

If the required amount of heat exceeds the predetermined amount of heat in step 8, the control board 9 selects the large capacity burner 5b. Then, in step 11, the control board 9 holds the large capacity solenoid valve 8b in a closed state, and the proportional control valve 8b
The opening degree of a is controlled according to the required amount of heat.

(Effects of the Invention) As explained above, the gas instantaneous water heater according to the present invention has a water flow that detects when hot water is being supplied and when the hot water supply is stopped by the flow of water on the upstream side of the connection part of the water supply pipe with the return pipe. Since the sensor is provided, hot water supply and hot water supply stop state can be reliably detected.

Therefore, the control period for intermittent combustion of the small capacity burner can be set to a different value, for example, 5 seconds in the hot water supply state and 30 seconds in the hot water supply stopped state. This makes it possible to reduce hunting in the hot water supply temperature and reliably maintain the hot water supply temperature and the circulating water temperature at a predetermined temperature.

In addition, in the hot water supply state, the small capacity burner can be continuously burned with a gas supply amount corresponding to the calculated amount of heat, so the on/off operation of the small capacity burner is reduced, and the durability of the small capacity burner is improved.

Furthermore, if the required amount of heat exceeds the maximum amount of heat of the small capacity burner, the large capacity burner is used for continuous combustion, making it possible to stably control the hot water supply temperature and circulating water temperature even if the required amount of heat spans a wide range. .

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the water heater of the present invention, and FIG. 2 is a flowchart showing an example of control of the water heater. 1...Heat exchanger, 2...Hot water supply pipe, 3...Water supply equipment, 4...Water supply pipe, 5a...Small capacity burner, 5b...Large capacity burner, 6a...Proportion for small capacity burner Control valve, 6b... Solenoid valve for small capacity burner, 8a... Proportional control valve for large capacity burner, 8b... Solenoid valve for large capacity burner, 9
... Control board, 10 ... Hot water temperature sensor, 11 ...
...Return pipe line, 12...Water flow sensor, 13...Incoming water temperature sensor, A...Signal related to outlet hot water temperature, B...
Signal related to flow rate, C...Signal related to inlet water temperature, E
...Opening/closing signal of solenoid valve of small capacity burner, F...
... Opening control signal of the proportional control valve for small capacity burners, G... Opening/closing signal of the solenoid valve for large capacity burners, H... Opening control signal of the proportional control valve for large capacity burners, P... Pump , S...Water flow sensor.

Claims (1)

[Claims] 1. A return pipe equipped with a pump is connected between the hot water supply pipe that connects the heat exchanger outlet to the hot water supply equipment and the water supply pipe that connects the heat exchanger inlet to the water supply source to form a circulation system line. A water flow sensor is installed on the upstream side of the connection with the return pipe of the water supply pipe to detect when hot water is being supplied and when the hot water supply is stopped by the flow of water, and when the required amount of heat is less than a predetermined amount of heat, It burns intermittently by repeating combustion and extinguishing at different cycles at different times and when hot water supply is stopped, and when the required amount of heat exceeds the predetermined amount of heat, it burns continuously to heat the heat exchanger. A small-capacity burner that maintains the hot water supply temperature at a predetermined temperature, and a large-capacity burner that maintains the hot water supply temperature at a predetermined temperature by continuously heating a heat exchanger when the required heat amount exceeds the maximum heat amount of the small-capacity burner. A gas instantaneous water heater that is equipped with a burner.