JPH1183183A - Hot water supply unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent hot water in a heat exchanger from boiling even when the flow rate of supply water is limited by an arrangement wherein the opening of an on/off valve is set smaller when the flow rate is limited to a low level by a flow rate limiting means as compared with when it is limited to a high level. SOLUTION: A remote controller 80 sets a low temperature region of 38-46 deg.C and a high temperature region of 48 deg.C or above. A controller 60 opens a solenoid valve 70 at the time of hot water delivery operation in the low temperature region and closes the solenoid valve 70 at the time of hot water delivery operation in the high temperature region. Consequently, the hot water being heated by a heat exchanger 30 is kept at high temperature even when low temperature hot water is delivered thus preventing generation of drain and it is prevented from boiling when high temperature hot water is delivered. Furthermore, delivery hot water temperature control for controlling the combustion amount is performed regulating gas supply through a proportional valve in a gas supply path to a burner 40 such that the delivery hot water temperature being detected by a delivery hot water temperature sensor 22 approaches a set temperature. The quantity of heat being applied to water flowing through heat exchanger 30 from the burner 40 is in the range of 75-250 kacl/min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water heater, and more particularly to a water heater of a bypass mixing type.

[0002]

2. Description of the Related Art A water heater provided with a bypass for bypassing a heat exchanger is conventionally known. Such a water heater was provided with an electromagnetic valve for opening and closing the bypass passage, and when the low temperature was set, the electromagnetic valve was opened to divide the water supplied from the water supply passage into the heat exchanger side and the bypass side and heated by the heat exchanger. By mixing hot water and water that has passed through the bypass, the hot water is heated to a temperature higher than the actual hot water temperature in the heat exchanger to suppress drain (condensation) and corrode the heat exchanger. To prevent Further, when the high temperature is set, the solenoid valve is closed and all the water supplied from the water supply channel is caused to flow to the heat exchanger side, thereby preventing the temperature of the hot water in the heat exchanger from rising excessively and boiling.

Further, a water governor for limiting the maximum flow rate of water supplied from a water supply channel is provided to prevent the amount of hot water with respect to a set temperature from exceeding the heating capacity of the appliance. In such a water governor, by incorporating a heat responsive member such as a shape memory alloy spring whose spring load changes according to the water temperature,
Even if the incoming water temperature varies due to seasonal changes, etc., the maximum flow rate is limited accordingly.

[0004]

When the hot water supply curan provided downstream of the heat exchanger is throttled, the pressure in the heat exchanger increases, and conversely, when the hot water supply callan is opened, the pressure in the heat exchanger decreases. Lower. On the other hand, due to the water temperature correction of the water governor provided on the upstream side of the heat exchanger, the maximum flow rate is restricted to be smaller in a situation where the incoming water temperature is low than in a situation where the incoming water temperature is high,
When the maximum flow rate is restricted to a small value on the upstream side, the pressure in the heat exchanger decreases accordingly. Therefore, when the hot water supply curan is opened and the maximum flow rate is limited by the water governor, there is a problem that the pressure in the heat exchanger is reduced, the boiling point is lowered, and the water tends to boil. Once the hot water in the heat exchanger boils even partially, the pressure in the heat exchanger increases due to the generated bubbles, and the bypass flow increases by that much, and the hot water temperature in the heat exchanger further rises. Eventually, the hot water in the heat exchanger boils completely and becomes empty. It is an object of the present invention to solve the above-described problem and to prevent the hot water of the heat exchanger from boiling even when the flow rate of incoming water is limited to a small value.

[0005]

A water heater according to the present invention, which solves the above-mentioned problems, comprises a heat exchanger for heating water supplied from a water supply passage by a combustion heat of a burner and sending the water to a tap water passage, and the heat exchanger. A bypass path for bypassing the water supply path and the hot water path, a hot water temperature control means for adjusting a combustion amount of the burner so that the hot water temperature approaches a set temperature, and an on-off valve for opening and closing the bypass path And a water heater provided with flow rate limiting means for varying a limit value of a maximum flow rate of water supplied to the appliance in the water supply channel, wherein the valve opening degree when the on-off valve is opened is determined by the flow rate limiting means. The point is to make the time when the flow rate is restricted to a small flow rate smaller than that when the flow rate is restricted to a large flow rate.

[0006] In the water heater of the present invention having the above-described configuration, the amount of combustion of the burner is adjusted so that the tap water temperature approaches the set temperature, and the water from the water supply passage is heated by the heat exchanger and sent to the tap water passage. In addition, at the time of low-temperature tapping, the bypass valve is opened to increase the hot water temperature in the heat exchanger to prevent drainage,
At the time of hot water supply, the bypass valve is closed to prevent boiling of the heat in the heat exchanger. Further, a flow rate limiting means for varying a limit value of a maximum flow rate of water supplied to the appliance is provided to limit the amount of hot water to be supplied according to the heating capacity of the burner. by the way,
If the maximum flow rate of water is restricted to a small flow rate in the water supply channel, the pressure in the heat exchanger will decrease and the boiling point will decrease, making it easier to boil. By reducing the time when the flow rate is restricted to a small flow rate as compared with the time when the flow rate is restricted to a large flow rate, the bypass ratio is reduced, and the temperature of the hot water in the heat exchanger is lowered to make it difficult to boil.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of the water heater of the present invention will be described below. FIG. 1 is a schematic configuration diagram of a water heater as one embodiment of the present invention. The water heater includes a heat exchanger 30 to which the water supply channel 10 and the hot water channel 20 are connected,
Burner 40 for heating water flowing through heat exchanger 30
, A bypass path 50 for bypassing the heat exchanger 30 and a controller 60 for controlling combustion. Water supply channel 10
A flow sensor 11 for detecting the flow rate of incoming water and a water governor 12 for limiting the maximum flow rate of water supplied to the appliance are provided on the upstream side of the branch portion A with the bypass passage 50. An outlet temperature sensor 2 for detecting the outlet hot water temperature of the heat exchanger 30 is located upstream of the junction B of the hot water path 20 with the bypass path 50.
1, a downstream tap temperature sensor 22 for detecting the temperature of the mixed hot water is provided downstream of the junction B. Further, the bypass path 50 is provided with an electromagnetic valve 70 for opening and closing the flow path.

The controller 60 includes a CPU, a RAM, and a ROM that constitute a well-known arithmetic and logic operation circuit (not shown).
It comprises an input interface for inputting signals from various sensors, an output interface for outputting drive signals to various actuators, and the like. The controller 60 is connected to a remote controller 80 including operation switches for performing external operations such as setting of a set temperature and a display for displaying the set temperature and the like.

In the remote controller 80, the set temperature is set in a low temperature range of 38 to 46 ° C. and a high temperature range of 48 ° C. or more. The controller 60 opens the solenoid valve 70 at the time of tapping operation when the set temperature is set to the low temperature range, and closes the solenoid valve 70 at the time of tapping operation when the set temperature is set to the high temperature range. By doing so, the hot water heated by the heat exchanger 30 is kept at a high temperature even when the hot water is discharged, and the generation of drain is prevented.
Make sure that the water heated at 0 does not boil. Further, the amount of gas supplied is adjusted by a proportional valve (not shown) provided in a gas supply path to the burner 40 so as to control the amount of combustion so that the temperature of the supplied hot water detected by the outlet temperature sensor 22 approaches the set temperature. The tap water temperature is controlled. At this time, the amount of heat given to the water flowing through the heat exchanger 30 by the combustion heat of the burner 40 is 250 kcal / min at the maximum and 75 kcal at the minimum.
/ min.

The water governor 12 is provided to limit the flow rate of water supplied to the appliance. The water governor 12 includes a shape memory alloy spring whose spring load changes according to the water temperature. Change the flow rate. In this embodiment, the maximum flow rate is changed so as to be 4.5 l / min when the water temperature is 5 ° C. and 7.1 l / min when the water temperature is 25 ° C. Also, the maximum temperature of the water at 60 ° C can be supplied.

As shown in FIG. 2, a solenoid valve 70 is provided with a diaphragm 71 for opening and closing the flow passage in the middle of the bypass passage 50.
And a pilot hole 7 provided integrally with the diaphragm 71.
Diaphragm receiver 72 which forms 2a and communication hole 72b
And a pilot valve 73 for opening and closing the pilot hole 72a.
An iron core 74 having a pilot valve 73 at its tip, and a spring 75 for urging the iron core 74 in the valve closing direction of the pilot valve 73.
And a coil 76 that is wound around the outer periphery of the sliding portion of the iron core 74 and that slides the iron core 74 in the valve opening direction of the pilot valve 73 by a magnetic force generated by being energized.

The diaphragm receiver 72 has a pilot hole 72a and a valve seat 72c at a central position, and a communication hole 72b at a position facing the water inlet 50a of the flow path. Further, a sheet portion 50c is formed in the water outlet portion 50b so as to be in close contact with the diaphragm 71 to block the flow path.

When the coil 76 is not energized,
As shown in FIG. 2A, the urging force of the spring 75 causes the pilot valve 73 to abut on the valve seat 72c, and the pilot hole 72a
Is closed, and the diaphragm 71 is
The flow path is blocked by being pressed against c. On the other hand, coil 7
6 is energized as shown in FIG.
The iron core 74 slides against the urging force of the spring 75 due to the magnetic force generated in the valve member 72, so that the pilot valve 73 separates from the valve seat 72c to open the pilot hole 72a, and the diaphragm 71
Is pushed by the pressure of the water inlet part 50a, and the sheet part 50c
And the flow path is opened.

In the solenoid valve having such a structure, the flow path is opened by opening the pilot valve 73 as described above, but the diaphragm 71 is not opened until the flow rate required to open the flow path to the maximum is reached. The opening changes according to the flow rate due to the restoring force. In this embodiment, focusing on this property, the solenoid valve 70 at a flow rate limited by the water governor 12 when the water temperature is low is considered.
Is changed so that it becomes smaller than the opening at the flow rate restricted by the water governor 12 when the water temperature is high, so that the bypass ratio at a small flow rate can be easily reduced as compared with a commonly used solenoid valve. doing. For example, by adopting a structure in which the seat portion 50c is closer to the diaphragm 71 side than a commonly used solenoid valve, it is possible to increase the reduction ratio of the bypass ratio with respect to the decrease in the flow rate.

FIG. 3 is a graph showing the relationship between the flow rate of water entering the appliance and the bypass ratio when the solenoid valve 70 is opened. As shown in this graph, when the incoming water flow rate is equal to or higher than the predetermined flow rate (about 5.8 l / min in this embodiment), the bypass ratio is stabilized at 40%. The degree is reduced and the bypass ratio is reduced. Therefore, at a small flow rate, the temperature of the hot water in the heat exchanger 30 decreases.

For example, when the incoming water temperature is 25 ° C., the water governor 1
2, the maximum flow rate is limited to 7.1 l / min. In such a state where the flow rate is large, the bypass ratio is 40%. On the other hand, when the incoming water temperature is 5 ° C., the maximum flow rate is limited to 4.5 l / min by the water governor 12, and in such a state where the maximum flow rate is small, the pressure in the heat exchanger 30 decreases and the boiling point decreases. However, at this time, the bypass ratio is less than 30%, and the temperature of the hot water in the heat exchanger 30 does not rise as much as at the time of a large flow rate, so that the boiling can be prevented. In this way, the bypass ratio changes so as to fall below the boiling limit.

On the other hand, if the bypass ratio is lowered, there is a concern that drainage may occur at a low temperature setting. However, the bypass ratio is lowered only when the flow rate is small, and when the flow rate is small, the water temperature is low. Even if the temperature is low, the temperature of the hot water in the heat exchanger 30 becomes high. For example, when the water temperature is 5 ° C., the set temperature is 38 ° C., and the bypass rate is 30%, the hot water temperature in the heat exchanger 30 becomes 52 ° C., which exceeds the drain limit temperature (46 ° C.), and the generation of drain is prevented. You.

As described above, according to the water heater of this embodiment, when the incoming water flow rate is a small flow rate, the maximum flow rate is controlled by the water governor 12 by reducing the bypass ratio when the solenoid valve 70 is opened. Even when the flow rate is limited to a small value, the boiling water in the heat exchanger 30 can be made difficult. In addition, the bypass ratio is reduced only when the incoming water flow rate is a small flow rate.
The temperature of the hot water in the tank exceeds the drain limit, and the generation of drain is prevented. Further, since it is not necessary to add a new special device to change the bypass ratio, it can be realized at low cost.

The embodiments of the present invention have been described above.
The present invention is not limited to these embodiments at all, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention. For example, in this embodiment, the apparatus using the water governor of the water temperature correction type has been described.
However, the present invention is not limited to this. For example, the present invention can be applied to a device using a flow control motor valve, such as controlling a water flow rate by moving a valve body by driving a motor.

[0020]

As described above in detail, according to the water heater of the present invention, even when the maximum flow rate of water is limited to a small flow rate in the water supply passage, the bypass of the solenoid valve is reduced by reducing the valve opening of the solenoid valve. Since the rate is lowered and the temperature of the hot water of the heat exchanger is lowered, the hot water of the heat exchanger is hardly boiled, so that a normal hot water can be maintained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a water heater as one embodiment.

FIG. 2 is a sectional view of a solenoid valve.

FIG. 3 is a graph showing a relationship between an incoming water flow rate and a bypass ratio.

[Explanation of symbols]

10: water supply channel, 12: water governor, 20: hot water channel,
30 heat exchanger, 40 burner, 50 bypass
60: controller, 70: solenoid valve

Claims (1)

[Claims] 1. A heat exchanger that heats water supplied from a water supply channel by combustion heat of a burner and sends the water to a hot water channel, and a bypass that bypasses the heat exchanger and communicates the water channel with the hot water channel. A hot water outlet temperature control means for adjusting the amount of combustion of the burner so that the hot water temperature approaches the set temperature; an on-off valve for opening and closing the bypass passage; and a maximum flow rate of water supplied to the appliance in the water supply passage. A water heater provided with a flow rate limiting means for varying a limit value, wherein the valve opening degree when the on-off valve is opened is limited to a small flow rate as compared with when the flow rate limiting means limits the flow rate to a large flow rate. A water heater characterized by reducing the time.