JPH05180508A - Method for controlling hot water feeding temperature at instantaneous hot water feeding - Google Patents

Abstract

PURPOSE:To perform a fast controlling to get the set temperature during reuse of a control valve by a method wherein the initial degree of opening of the control valve is set in relation with a heat exchanging outlet temperature and a fed water temperature in reference to the degree of opening of a flow rate control valve at the heat exchanger just before a previous stopping of operation. CONSTITUTION:The degree of opening of a control valve 5 is set in such a way that the outlet temperature of a heat exchanger 1 can be controlled to a predetermined temperature under a normal state during usage of a hot water feeder (when the hot water feeding temperature reaches the set temperature set by a user). Then, the degree of opening is adjusted at the predetermined rate (a rate of the degree of opening set in the case of refeeding of hot water in respect to a stopped degree of opening set in timed relation) in reference to the degree of opening of the control valve 5 (the degree of opening under a stopped condition) just before its stopping condition when its reuse is carried out, the hot water of high temperature remained in the heat exchanger 1 is mixed with water fed from a water bypassing system during refeeding of hot water and then the hot water is fed. In the case of performing refeeding of hot water, the initial degree of opening is set at a predetermined rate in reference to the degree of opening just before its stopping state. With such an arrangement, a fast controlling to the set temperature can be attained during its reuse.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot water heater (hereinafter referred to as "water heater") which is used for intermittent hot water discharge during intermittent use.
The present invention relates to a hot water temperature control method in which when the hot water temperature near the outlet of a heat exchanger is higher than a user's set temperature, this high amount is alleviated by mixing cold water introduced from the bypass side and the hot water is discharged.

[0002]

2. Description of the Related Art If a hot water heater is used intermittently, a so-called after-boiling phenomenon may cause a burn or the like and cause an unpleasant feeling. In order to solve this, as shown in FIG. 2, at the time of re-hot water, the controller 2 opens the bypass-side control valve 3 at the beginning, and then the hot water is gradually discharged for a certain period of time, that is, until hot water is discharged by post-boiling. It controls the mixing ratio of. Further, this control is always controlled for a predetermined time, and is not related to the actual temperature at the outlet of the heat exchanger 1 or the set temperature. FIG. 3 is an explanatory diagram of the opening degree of the bypass side control valve 3, and the valve opening degree is gradually opened with the lapse of time. Reference numeral 4 in the figure is an overall flow control valve.

[0003]

As described above, when the problem of post-boiling is controlled by time, when the actual outlet temperature is different due to natural heat dissipation due to the set temperature at the previous time or the passage of time until reuse. (Almost always different),
There is a problem in that the temperature characteristics of hot water discharged during reuse are poor and the usability is poor. For example, when the shower is used and then hot water is again discharged, hot water having a temperature higher or lower than the temperature set by the user is discharged until the water heater is in a steady operation.

An object of the present invention is to provide a control method capable of quickly controlling the set temperature during reuse.

[0005]

The control method according to the present invention is as follows.

A heat exchanger side flow control valve is attached to the outlet side of the heat exchanger, the valve opening degree of this control valve immediately before the stop of use is stored, and the stored valve opening degree is used as a reference at the time of reuse. As a method for controlling the outlet heated water temperature in an instantaneous water heater, the initial valve opening is set at a predetermined rate.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, 1 is a heat exchanger, 2 is a controller,
Reference numeral 3 is a bypass control valve, 4 is an overall flow rate control valve, and 5 is a heat exchanger side flow rate control valve.

In the steady state (when the hot water supply temperature reaches the temperature set by the user) while using the hot water supply device, the outlet temperature of the heat exchanger 1 side can be controlled to a predetermined temperature. The opening degree is set, and when reused (when the temperature of the outlet of the heat exchanger 1 is higher than the set temperature), the valve opening degree of the control valve 5 immediately before stop (opening degree at stop) is used as a reference, and a predetermined ratio is set. (Hereinafter referred to as a mixing ratio table, which is set in time, the ratio of the opening degree set at the time of re-hot water to the opening degree at the time of stop) is adjusted so that it remains in the heat exchanger 1 during re-hot water supply. Hot water is mixed with water from the water side bypass to supply hot water. At the time of re-hot water supply, the initial opening is set at a predetermined ratio based on the opening immediately before the stop, so that the mixing suitable for the set temperature can be performed from the beginning. The mixing ratio is a value determined by the relationship between the outlet temperature on the heat exchanger 1 side and the incoming water temperature.

Temperature during steady combustion at the outlet of the heat exchanger: Ts Temperature near the outlet of the heat exchanger at the time of tapping again: Ta Water inlet temperature: to User preset temperature: If ts is distributed to the heat exchanger during steady combustion The ratio R

[0010]

[Equation 1]

The ideal distribution ratio r when tapping again is

[0012]

[Equation 2]

Therefore, the ratio of the opening when re-opening hot water to the opening immediately before the stop is

[0014]

[Equation 3]

And is expressed as a function of the heat exchanger outlet temperature and the incoming water temperature. The control after the initial setting is the same as the conventional example.

[0016]

INDUSTRIAL APPLICABILITY As described above, the present invention, as a method of controlling the temperature at the time of re-hot water, does not control the absolute valve opening in accordance with the passage of time as in the conventional case, but immediately before the last stop. Based on the valve opening of the heat exchanger side flow control valve, the initial opening of the control valve is set in a fixed ratio, that is, the relationship between the heat exchange outlet temperature and the incoming water temperature. And the usability of the water heater is greatly improved.

[Brief description of drawings]

FIG. 1 is an explanatory view of a water heater embodying the present invention.

FIG. 2 is an explanatory diagram of a conventional control method.

FIG. 3 is an explanatory view of a conventional valve opening degree.

[Explanation of symbols]

 1 heat exchanger 2 controller 3 bypass side flow rate control valve 4 overall flow rate control valve 5 heat exchanger side flow rate control valve

Claims (1)

[Claims] 1. A momentary hot water supply system in which a valve opening of a control valve immediately before the last stop of use is stored, and an initial valve opening is set at a predetermined rate with reference to the stored valve opening when reused. For controlling the temperature of tap water in a water heater.