JP3099488B2 - Water heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water heater having a bypass circuit for improving hot water temperature characteristics.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional water heater of this type includes a water supply pipe 32, a heat exchanger 33, a hot water supply pipe 34, and a hot water tap 4.
0 constitutes a hot water supply circuit. And the flow rate detector 31,
Hot water temperature detector 37, bypass pipe 35 and bypass valve 36
And branches off from the water supply pipe 32 and joins the hot water supply pipe 34 on the upstream side of the hot water temperature detector 37 to form a bypass circuit.
Reference numeral 38 denotes a heating burner for heating water in the heat exchanger 33. The operation is controlled by the controller 39.

In the operation of the above configuration, when the hot water tap 40 is opened, water is supplied to the hot water supply circuit by tap water pressure. This flow of water is detected by the flow rate detector 31, the operation of the heating burner 38 is started to heat the passing water and supply hot water, and the bypass valve 36
And open the bypass circuit. At this time, the heating amount is controlled so that the value detected by the hot water temperature detector 37 matches the value set by the controller 39. When the hot water tap 40 is closed, the bypass valve 36 is closed and the heating burner 38 is closed.
Stop operation of.

[0004]

However, in the above-mentioned conventional configuration, once the hot water supply is stopped, the water in the heat exchanger 33 is heated to a set value or more by the residual heat of the heating burner 38 and the heat exchanger 33, and the hot water is re-supplied. At the beginning of time, hot water flows out, that is, overshoot of the hot water temperature occurs. For this reason, water is passed through the bypass circuit for the purpose of reducing this overshoot. However, since water is always supplied during hot water supply, if the flow ratio on the bypass circuit side is set large, the hot water temperature passing through the heat exchanger 33 will increase. It is necessary to set it, and a problem occurs durably. Therefore, there is a problem that the flow rate ratio on the bypass circuit side can only be set small, and there is a limit to the rate of decrease in overshoot of the hot water temperature at the beginning of hot water supply.
In addition, since the hot water that has passed through the heat exchanger 33 and the water that has passed through the bypass circuit are mixed, and the hot water temperature is detected and the hot water temperature is controlled, the hot water temperature control becomes unstable if the mixing is not sufficient. There were also issues.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and prevents high-temperature hot water from being discharged at the initial stage of re-hot water supply and prevents unstable hot water temperature control, thereby providing a safe and highly usable hot water supply. It is intended to provide a machine.

[0006]

In order to achieve the above object, the present invention provides a hot water supply circuit comprising a water supply pipe having a flow rate detector, a heat exchanger, and a hot water supply pipe having a hot water temperature detector. A bypass pipe branching from the water supply pipe and joining a hot water supply pipe on the downstream side of the hot water temperature detector, and having a bypass valve in the middle thereof;
The heating device, the bypass valve is opened at the time when the flow rate detector detects the flow rate, and then detected by the hot water temperature detector.
Starts the comparison operation between the hot water temperature and the set value.
Control to close the bypass valve when a predetermined temperature is reached
And the controller is configured to open the bypass valve.
Not to perform the comparison operation until a certain time elapses
It was done.

[0007]

According to the present invention, the above configuration prevents hot water from flowing out by passing a sufficient amount of water to prevent overshooting of hot water temperature into the bypass circuit only at the beginning of hot water supply. Can stabilize the hot water temperature control by removing the unstable mixing factors by making the bypass circuit non-water-permeable.

[0008]

An embodiment of the present invention will be described below with reference to FIG. As shown in the figure, the water heater comprises a hot water supply pipe 2, a heat exchanger 3, a hot water supply pipe 4, and a hot water tap 10.
It has a flow rate detector 1, a hot water temperature detector 7, a bypass pipe 5 and a bypass valve 6, and branches off from the water supply pipe 2 and joins with the hot water supply pipe 4 downstream of the hot water temperature detector 7 to form a bypass circuit. ing. Reference numeral 8 denotes a heating burner for heating water in the heat exchanger 3, and the operation thereof is controlled by a controller 9.

The operation in the above configuration will be described with reference to FIG. In the figure, the solid line indicates the hot water temperature after mixing by the bypass circuit, and the broken line indicates the hot water temperature before the hot water mixing. When the hot water tap 10 is opened, water is supplied to the hot water supply circuit by tap water pressure. The flow detector 1 detects the flow of water, starts the operation of the heating burner 8, heats the passing water to supply hot water, and opens the bypass valve 6 to flow water to the bypass circuit. The heating amount is controlled so that the value detected by the hot water temperature detector 7 and the set value of the hot water temperature set by the controller 9 match. Bypass valve 6
Until the predetermined time (ΔT) elapses, regardless of the temperature of the hot water temperature detector 7, the open state is forcibly held, and thereafter, the hot water temperature detected by the hot water temperature detector 7 is compared with a set value, and When the temperature drops to a temperature Δt higher than the set value of the hot water supply temperature, the bypass valve 6
Close. Thereafter, hot water is supplied to the bypass circuit in a non-water-passing state. When the hot-water tap 10 is closed, the operation of the heating burner 8 is stopped.

According to the configuration of the above embodiment, the flow rate on the bypass circuit side can be set large without increasing the temperature of the hot water passing through the heat exchanger 3, so that the overshoot of the hot water temperature at the initial stage of hot water supply is reduced. At the same time, there is an effect that problems in durability of the heat exchanger 3 are solved. In addition, since the bypass circuit side is in a non-flowing state except in the initial stage of hot water supply, there is no unstable factor of hot water mixing, and there is also an effect that stable hot water temperature control becomes possible.

[0011]

As described above, according to the present invention, the bypass valve of the water bypass circuit is opened at the time when the flow rate is detected by the flow rate detector, and is set to the hot water temperature detected by the hot water temperature detector after a lapse of a predetermined time. because comparing initiate value, the bypass valve when the value reaches a predetermined temperature and is configured to be closed, hot water supply
When the bypass valve is controlled with unstable detected hot water temperature at the beginning of the start
To avoid overshoot and suppress overshoot
This makes it possible to perform a proper hot and cold water mixing operation. In addition, the flow rate ratio on the bypass circuit side can be set large, and the bypass circuit side is in a non-water-permeable state except in the initial stage of hot water supply, so that there is no unstable element such as hot water mixing. Therefore, the overshoot at the beginning of hot water supply is reduced, high-temperature hot water is prevented from flowing out at the initial time of hot water replenishment and hot water temperature control is prevented from becoming unstable. This has the effect.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a water heater according to one embodiment of the present invention.

FIG. 2 is a characteristic diagram of hot water supply temperature of the water heater.

FIG. 3 is a system configuration diagram of a conventional water heater.

[Explanation of symbols]

 Reference Signs List 1 flow rate detector 2 water supply pipe 3 heat exchanger 4 hot water supply pipe 5 bypass pipe 6 bypass valve 7 hot water temperature detector 8 heating burner (heating device) 9 controller

Claims (1)

(57) [Claims] A feed pipe having a flow detector, a heat exchanger,
A hot water supply circuit configured in the order of a hot water supply pipe provided with a hot water temperature detector,
A bypass pipe that branches off from the water supply pipe and joins a hot water supply pipe on the downstream side of the hot water temperature detector, and has a bypass valve in the middle thereof, a heating device, and the bypass valve when the flow rate detector detects a flow rate. Open, and then check with the hot water temperature detector.
Starts the comparison operation between the output hot water temperature and the set value, and
When the fruit reaches a predetermined temperature, the bypass valve is closed.
A controller that opens the bypass valve.
Do not perform the comparison operation until a certain time has passed since
Sea water heater.