JPH06288632A - Water heater - Google Patents

Abstract

(57) [Summary] [Purpose] In a bypass mixing type hot water supply device,
Prevents the heat exchanger outlet temperature from becoming too hot and boiling. [Composition] In a case where hot water from a heating path and water from a bypass path are mixed to control hot water discharge at a set temperature, a heat exchanger outlet is calculated based on the incoming water temperature and the set temperature for hot water discharge control, and the heat exchanger outlet is installed in the bypass Control the opening and closing of the bypass water solenoid valve. [Effect] The heat exchanger outlet temperature is calculated and predicted based on the incoming water temperature and the set temperature, and the opening / closing of the bypass water solenoid valve is determined during the initial transient state of hot water control. Unlike, it stabilizes the temperature characteristics of hot water and prevents boiling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bypass mixing type hot water supply apparatus which mixes hot water passing through a heat exchanger with water having passed through a bypass passage to release hot water having a preset temperature.

[0002]

2. Description of the Related Art In a conventional bypass mixing type hot water supply apparatus, in order to avoid low temperature corrosion of the heat exchanger due to low temperature water passing through the heat exchanger, a passage for bypassing the heat exchanger is provided. Hot water having a temperature higher than the set temperature is discharged from the exchanger, and water from the bypass passage is mixed to obtain hot water having the set temperature.

[0003]

In such a conventional bypass mixing type hot water supply apparatus, the bypass opening / closing state of the bypass water solenoid valve provided in the bypass passage is determined only by the set temperature. From the viewpoint of low temperature corrosion prevention, it is desirable to keep the heat exchanger temperature at 50 ° C. or higher, so the set temperature was set at 50 ° C. or higher.

However, in a model in which the ratio of the heat exchanger flow rate to the bypass flow rate (hereinafter referred to as the bypass ratio) is large, it is 50
In a state where the bypass is opened at a set temperature of ℃ or less, the outlet temperature of the heat exchanger may become too high and boils. When boiling occurs, it causes adverse effects such as an increase in noise due to boiling noise, instability of tapping temperature due to fluctuations in flow rate, and adhesion of scale in the pipe of the heat exchanger.

The present invention has been made in view of the above drawbacks of the prior art, and an object of the present invention is to provide a hot water supply apparatus which prevents boiling in the heat exchanger and can always be used normally and stably. It is in.

[0006]

A hot water supply apparatus according to the present invention includes a heating passage passing through a heat exchanger, a bypass passage bypassing the heat exchanger, and a bypass water solenoid valve provided in the bypass passage.
A hot water supply system that has an incoming water thermistor that detects the incoming water temperature and a temperature setting unit that sets the outgoing hot water temperature, and mixes the hot water from the heating path with the water from the bypass path to control the hot water at the set temperature. The apparatus is characterized in that the heat exchanger outlet temperature is calculated on the basis of the incoming water temperature and the set temperature, and the control means for controlling the opening / closing of the bypass water solenoid valve is provided based on the calculated value.

[0007]

According to the present invention, the heat exchanger outlet temperature when the bypass passage is opened and water is mixed is calculated and predicted according to the incoming water temperature and the set temperature, and the opening / closing of the bypass water solenoid valve is determined.
The state of the bypass water solenoid valve can be determined in the initial transient state of hot water discharge control, hot water can be used without unstable hot water temperature characteristics, and boiling can be prevented.

[0008]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention, in which a heating passage 2 passing through a heat exchanger 1 is connected with a water inlet passage 3 and a hot water supply passage 4 and a heat exchanger. A bypass path 5 for bypassing 1 is provided. The total flow rate Q into the inlet 3
A water amount sensor 6 for detecting t and a water input thermistor 7 for detecting the water temperature Tw are provided. Heating path 2
Is provided with a water solenoid valve 8 and a water amount sensor 9 for detecting the water flow rate Qk. Bypass path 5 includes bypass path 5
A bypass water solenoid valve 10 for opening and closing is provided. The hot water supply passage 4 is provided with a hot water outlet thermistor 11 for detecting the hot water outlet temperature Th and a water amount servo 12 for adjusting the hot water outlet flow rate. 1
Reference numeral 3 denotes a temperature setting unit for setting the hot water temperature, which inputs detection signals of the water amount sensor 6, the incoming water thermistor 7, the water amount sensor 9, the hot water thermistor 11, etc., and the water solenoid valve 8, the bypass water solenoid valve 10, the water amount. The set hot water temperature Ts is input to the control unit 14 that controls the servo 12. The burner 15 for heating the heat exchanger 1 includes a gas proportional valve 16 controlled by the controller 14.
The burning ability is adjusted by.

FIG. 2 is a flow chart showing the control operation of the hot water supply apparatus of the present invention. The operation switch is turned on (S21),
The minimum operating flow rate (MOQ), for example, Qt>
If it is 3.5 liters / min or more (S22), the water solenoid valve 8 is opened and water flow to the heat exchanger 1 is started (S22).
23). Bypass water solenoid valve 10 provided in the bypass passage 5
If the set temperature Ts is in the set temperature range of 38 to 75 ° C., the bypass water solenoid valve 10 is closed at 50 ° C. or higher regardless of other conditions, and opened at 50 ° C. or lower regardless of other conditions. The outlet temperature Tk of the container 1 is increased (S24). At this time, the outlet temperature Tk
Is Tk = (1 + a) Ts-a when the bypass ratio is 1: a.
Tw, for example, if the bypass ratio is 1: 1, Tk = 2
The temperature becomes Ts-Tw, and the outlet temperature Tk of the heat exchanger, which is necessary for the outlet water temperature Th = the set temperature Ts when the water inlet temperature is low, approaches the boiling region. That is, for example, the incoming water temperature Tw =
Assuming 5 ° C and set temperature Ts = 46 ° C, 87 ° C from the previous equation
Becomes Since the previous formula is a formula of only the set temperature and the incoming water temperature, it can be determined immediately after the use of hot water supply is started, and the state of the bypass water solenoid valve 10 can be determined during the initial transient state of the outgoing hot water control. Set temperature T
The heat exchanger outlet temperature Tk predicted by s is calculated to make the open / close determination. Then, for example, if Tk <80 ° C., the bypass water solenoid valve 10 is left open, and if it is determined to be 80 ° C. or higher, the bypass water solenoid valve 10 is closed (S26). Next, when the minimum operating flow rate (MOQ) is ON, the flow rate Qk of the heating passage 2>
Determine whether it is 1.5 liters / min (S2
7). Then, a pre-check is performed (S28), and if OK, the fan motor is turned on (S29), and the ignition sequence is started. In this way, the opening / closing state of the bypass water solenoid valve 10 can be determined in the initial transition state of the hot water discharge control, so that the hot water temperature characteristics can be used without being unstable.

[0010]

As described above, according to the present invention, the exit temperature of the heat exchanger is calculated and predicted based on the incoming water temperature and the set temperature, and the opening / closing of the bypass water solenoid valve is determined to determine the state during the initial transient state of the tap water control. Unlike the conventional method of determining the state of the bypass water solenoid valve only by the set temperature, the outlet heated water temperature characteristic is stable and boiling can be prevented. Therefore, it is possible to provide a hot water supply apparatus which is free from noise due to boiling, instability of hot water temperature, sticking of scale, and the like.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a control operation of the present invention.

[Explanation of symbols]

 1 Heat Exchanger 2 Heating Path 5 Bypass Path 7 Inlet Water Thermistor 10 Bypass Water Solenoid Valve 13 Temperature Setting Section 14 Control Section

Continuation of the front page (72) Inventor Satoshi Umaki, Noritsu Co., Ltd., 32, Akashi-cho, Chuo-ku, Kobe-shi, Hyogo Prefecture (72) Inventor Takao Po, No. 32 Akashi-cho, Chuo-ku, Kobe, Hyogo Prefecture (72) Invention Hidekazu Fukui 32, Akashi-cho, Chuo-ku, Kobe-shi, Hyogo Noritu Co., Ltd. (72) Inventor Atsuhiro Morishita, Atsushi 32, Akashi-cho, Chuo-ku, Kobe-shi, Hyogo (72) Inventor Yu Kawaguchi Chuo, Kobe-shi, Hyogo 32 Akashi-cho, Tokyo

Claims (1)

[Claims] 1. A heating path that passes through a heat exchanger, a bypass path that bypasses the heat exchanger, a bypass water solenoid valve provided in the bypass path, and a water entering thermistor that detects the incoming water temperature.
In a hot water supply device having a temperature setting unit for setting the hot water temperature, the hot water of the preset temperature is controlled by mixing hot water from the heating path and water from the bypass path. A hot water supply device comprising a control means for calculating the outlet temperature of the heat exchanger based on the calculated value and controlling the opening / closing of the bypass water solenoid valve based on the calculated value.