JPH0762530B2 - 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. Specifically, the present invention is a bypass mixing type hot water supply device with an immediate hot water function, which keeps the hot water in a pipe at a constant temperature so as not to be cooled due to heat dissipation, and allows an appropriate temperature hot water to be discharged immediately when the hot water is discharged. Regarding

[0002]

2. Description of the Related Art In recent hot water heaters, in order to meet the demands for downsizing and securing a sufficient amount of hot water, a passage for bypassing the inlet and outlet of the heat exchanger is provided, and the heat exchanger has a temperature higher than a desired set temperature. The bypass mixing method, in which the hot water discharged from this heat exchanger is mixed with the water that has passed through the bypass passage to supply hot water of the desired set temperature, has become mainstream. There is.

Further, in this bypass mixing type hot water supply apparatus, when a hot water tap such as a calan is opened,
2. Description of the Related Art A hot water supply device provided with an immediate hot water function is used so that hot water having an appropriate temperature can be discharged without discharging the residual water cooled in the pipe.

(Configuration of Hot Water Supply Device with Immediate Hot Water Function) FIG. 1 is a schematic configuration diagram of a hot water supply device with an immediate hot water function which has been conventionally used. 1 is a water heater main body, 2 is a water heater main body 1
This is a control unit that controls the hot water supply temperature and the instant hot water function. The hot water supply passage 3 has an inlet 5 for the heat exchanger 4 and an inlet 5 for city water or the like.
It is composed of a water supply pipe 3a connecting between the two, and a hot water supply pipe 3b connecting between the outlet of the heat exchanger 4 and the hot water tap 6 such as a calan or a shower. A bypass passage 7 is provided between the water supply pipe 3a and the hot water supply pipe 3b so as to bypass between the inlet and the outlet of the heat exchanger 4. Furthermore, hot water supply piping 3
A hot water supply return pipe 8 is disposed between the vicinity of the hot water supply plug 6 of b and a position closer to the heat exchanger 4 than the bypass passage branch point of the water supply pipe 3a.

A water amount sensor 9 for detecting the amount of water flowing into the heat exchanger 4 is provided near the heat exchanger inlet of the water supply pipe 3a.
Is provided. A flow rate servo valve 10 for controlling the flow rate of hot water flowing out of the heat exchanger 4 is provided near the outlet of the heat exchanger of the hot water supply pipe 3b, and heat is supplied downstream of the bypass passage connection point of the hot water supply pipe 3b. A hot water outlet temperature sensor 11 such as a thermistor for detecting a mixing temperature Tm between the hot water discharged from the exchanger 4 and the water passing through the bypass passage 7 is provided. Further, the bypass passage 7 is provided with a water amount sensor 12 for detecting the amount of water flowing through the bypass passage 7 and a bypass flow rate servo valve 13 for controlling the flow amount of water flowing through the bypass passage 7. Furthermore, in the hot water supply return pipe 8,
A circulation pump 14 for circulating hot water, a temperature sensor 15 such as a thermistor for detecting the temperature of the hot water returned from the hot water supply pipe 3b side to the hot water supply pipe 3a side through the hot water supply return pipe 8.
From the hot water supply pipe 3a side through the hot water supply return pipe 8, the hot water supply pipe 3
Backflow prevention valve 1 to prevent hot water from flowing back to the b side
6 is provided. Reference numeral 17 is a gas burner for heating the water flowing in the heat exchanger, and 18 is a capacity control device for adjusting the combustion power of the gas burner.

Water amount sensors 9 and 12, hot water temperature sensor 11
The outputs of the temperature sensor 15 and the temperature sensor 15 are input to the control unit 2, and the flow rate servo valves 10 and 13, the capacity control device 18, and the circulation pump 14 are controlled by the control unit 2 based on the outputs of the above-mentioned sensors.

The desired hot water supply temperature from the hot water tap 6 can be freely set by the user. When the set temperature Ts of the hot water tap 6 is input to the control unit 2, the hot water from the heat exchanger 4 is discharged. The temperature is set to a temperature higher than the set temperature Ts of the hot water tap 6 (this is referred to as a pseudo set temperature) Th.

(Method for controlling hot water temperature of the hot water supply device) Water inlet 5
The water flowing into the water supply pipe 3a from the inside is distributed to the heat exchanger 4 side and the bypass passage 7 side. The water flowing into the heat exchanger 4 side is heated by the bus burner 17 when passing through the heat exchanger 4. At this time, the capacity control device 18 that adjusts the combustion power of the gas burner 17 is feed-forward controlled by the control unit 2 based on the amount of water detected by the water amount sensor 9, and the hot exchanger 4 generates hot water of the pseudo set temperature Th. It will be bathed. Hot water having a pseudo set temperature Th discharged from the heat exchanger 4 is mixed with water that has passed through the bypass passage 7 and discharged from the hot water tap 6. The mixing temperature Tm of the hot water discharged from the hot water tap 6 is monitored by the hot water temperature sensor 11, and the control unit 2 sets the mixing temperature Tm to the set temperature Tm.
The bypass flow rate servo valve 13 (or the flow rate servo valve 1 of the hot water supply pipe 3b and the bypass passage 7) so that it becomes equal to s.
0, 13) is feedback-controlled.

Further, in this hot water supply apparatus, the hot water in the pipe radiates heat to cool when the hot water supply is stopped, and when the hot water tap 6 is opened, cold water is discharged from the hot water tap 6 to give the user an unpleasant feeling. In order to prevent this, it has an instant hot water function. This immediate hot water function means that when hot water supply is stopped and the immediate hot water switch is turned on, the hot water is returned to the inside of the pipe by using the hot water supply return pipe 8 and the circulation pump 14 to heat it by the heat exchanger. The temperature of the hot water in the pipe is kept within a certain temperature range.

(Immediate Hot Water Operation by Conventional Hot Water Supply Device) In the prior art, the hot water supply device is controlled as follows in order to realize the immediate hot water function. The operation of the immediate hot water function in the conventional hot water supply apparatus is shown in the flowchart of FIG. 4, and the immediate hot water function by the control unit will be described with reference to FIG.

When the hot water tap 6 is closed and the hot water switch is turned on (S51), first, the bypass flow rate servo valve 13 is fully closed (S52) to bypass the hot water in the pipe without passing through the heat exchanger 4. Prevent a short pass through the passage 7. Then, the hot water temperature T in the pipe is compared with a predetermined instant hot water operation start temperature T1 (S53). If the hot water temperature T in the pipe is higher than the instant hot water operation start temperature T1, the hot water temperature T in the pipe And continues to compare the hot water temperature T with the immediate hot water operation start temperature T1. When the hot water temperature T in the pipe is gradually lowered to the hot water operation start temperature T1 or lower, the operation of the circulation pump 14 is started (S54). When the circulation pump 16 is operated, the hot water in the pipe circulates through the route of the water supply pipe 3a → the heat exchanger 4 → the hot water supply pipe 3b → the hot water supply return pipe 8 (the route shown by the arrow in FIG. 1). When the hot water circulates in this way, it is monitored whether the flow rate of the hot water flowing through the heat exchanger 4 is equal to or higher than the minimum operating flow rate (MOQ) (S55). If this flow rate is less than or equal to the minimum operating flow rate, it is determined that an abnormality has occurred, and the hot water operation is interrupted or an abnormality is reported to take an abnormal action. When it is confirmed that the flow rate is equal to or higher than the minimum operating flow rate, the gas burner 17 is ignited and the hot water in the pipe is heated by the heat exchanger 4 to control the hot water temperature in the pipe (S56). Then, the hot water temperature T in the pipe is compared with a predetermined immediate heating operation end temperature T2 (> T1) (S5).
7) If the hot water temperature T has not reached the immediate warming operation end temperature T2, the process returns to step S55 to check whether the flow rate is below the minimum operating flow rate. Thus, until the hot water temperature T reaches the immediate hot water operation end temperature T2, step S55.
When the hot water temperature in the pipe monitored by the temperature sensor 15 becomes equal to or higher than the instant hot water operation end temperature T2 by repeating S57 to S57, the combustion of the gas burner 17 is stopped (S58), and the circulation pump 14 is post-operated for a certain period of time. Stop (S5
9, 60). After the circulation pump 14 is stopped, it is monitored again whether the hot water temperature T is equal to or lower than the immediate warming operation start temperature T1 (S53), and when the hot water temperature T drops to the immediate warming operation start temperature T1, the above is performed. The flow after step S53 is repeated.

By the above-described processing, hot water having a hot water operation start temperature T1 or higher and a hot water operation end temperature T2 or lower is always stored in the pipe, and when a hot water tap such as a calan is opened, a comfortable temperature is immediately obtained. Hot water is discharged.

(Problem of the conventional hot water supply device) However, in the control system of the immediate hot water function in the conventional hot water supply device, the circulation pump is operated after the bypass flow rate servo valve is fully closed for immediate hot water operation. Since it has started, if the hot water operation is started immediately after the hot water tap is closed, the high temperature hot water remaining in the hot water supply pipe from the heat exchanger to the bypass passage connection point will flow to the hot water supply pipe, There will be an area of hot water in a part of it. If the hot water tap is opened again before the hot water region has fully diffused, the hot water may be discharged from the hot water tap, which is dangerous.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the drawbacks of the above-mentioned conventional examples, and the purpose thereof is to close the hot water tap immediately after starting hot water operation,
It is an object of the present invention to provide a hot water supply device with an immediate hot water function, in which there is no fear that hot water will be discharged even if the hot water tap is opened again.

[0015]

The hot water supply apparatus of the present invention comprises a hot water supply passage having a heat exchanger, a heating device for heating the heat exchanger, and hot water supply so as to bypass the inlet side and the outlet side of the heat exchanger. Through the bypass passage connected to the hot water passage, the flow control valve provided in the bypass passage, the hot water supply return pipe connected between the hot water supply passage near the hot water tap and the heat exchanger inlet side of the hot water supply passage, and the hot water return pipe A circulation pump that circulates the hot water, a hot water temperature detector that detects the temperature of the hot water that circulates through the hot water return pipe, and a circulation pump that operates while the hot water is stopped to circulate the hot water.
In a hot water supply apparatus having an immediate hot water operation control unit that keeps the temperature of the circulating hot water within a predetermined range, the instant hot water operation control unit causes the circulating pump to start operating after a certain period of time elapses. The feature is that the flow control valve in the bypass passage is fully closed.

[0016]

According to the present invention, the flow control valve in the bypass passage is completely closed after a certain period of time has passed after the operation of the circulation pump is started without closing the flow control valve in the bypass passage before the operation of the circulation pump is started. Since it is closed, when the operation of the circulation pump is started, the hot water in the heat exchanger and the water in the bypass passage flow into the hot water supply circuit and are mixed, and a hot water area is generated in the hot water supply circuit. Can be prevented. Therefore, even if the hot water tap is opened immediately after the start of the hot water operation, there is no danger of hot water coming out of the hot water tap, and it can be used safely.

Further, after a lapse of a certain time after the operation of the circulation pump, the flow rate adjusting valve in the bypass passage is fully closed.
The hot water in the pipe can be prevented from short-circuiting through the bypass passage, and the hot water in the pipe can be heated or kept warm while the hot water having a minimum working flow rate or more is flowed to the heat exchanger.

[0018]

EXAMPLE As a hot water supply apparatus according to an example of the present invention,
Since the same structure as the bypass mixing type hot water supply device with the immediate hot water function shown in FIG. 1 can be used, detailed description thereof will be omitted, and the same components will be denoted by the reference numerals used in FIG. The description will be made using the same reference numerals.

FIG. 2 is a block diagram showing a structure for controlling hot water operation in one embodiment of the present invention. In addition to a hot water supply temperature control unit (not shown) for controlling the hot water supply temperature from the hot water tap 6, an immediate hot water operation control unit 2a is provided in the control unit 2 as shown in FIG. , Hot water operation control unit 2
a is a timer 2 for fully closing the bypass flow rate servo valve 13 after a lapse of a certain time after the operation of the circulation pump 14 is started.
d. Also, in the control unit 2, a setting device 2 for setting a hot water operation start temperature T1 and a hot water operation end temperature T2.
b and 2c are provided, and the hot water operation start temperature setting device 2 is provided.
Outputs of b and the hot water operation end temperature setting device 2c are connected to the hot water operation control unit 2a. The immediate hot water operation start temperature setting unit 2b and the immediate hot water operation end temperature setting unit 2c are connected to the output of a setting device 19 for inputting a desired temperature Ts of hot water supplied from the hot water tap 6. When the set temperature Ts is input from the device 19, the hot water operation start temperature setting device 2b
And the immediate hot water operation end temperature setting device 2c has a set temperature T, respectively.
s to start hot water operation start temperature T1 and instant hot water operation end temperature T2
Is calculated and the result is input to the hot water operation control unit 2a.
Further, the outputs of the instant hot water switch 20, the water amount sensor 9, and the temperature sensor 15 are connected to the instant hot water operation control unit 2a,
The immediate hot water operation control unit 2a uses the bypass flow rate servo valve 13 and the circulation pump based on the detected values of the water amount sensor 9 and the temperature sensor 15 and the input values of the immediate hot water operation start temperature T1 and the immediate hot water operation end temperature T2. 14, control the capacity control device 18,
Immediate hot water operation.

FIG. 3 is a flow chart showing the operation of the instant hot water function by the instant hot water operation controller. The immediate hot water function according to this embodiment will be described below with reference to the flowchart of FIG. When the hot water tap 6 is closed and the hot water switch 20 is turned on (S21), the hot water temperature T in the pipe detected by the temperature sensor 15 is compared with the hot water operation start temperature T1 (S21).
22) If the hot water temperature T in the pipe is higher than the immediate hot water operation start temperature T1, the hot water temperature T in the pipe is monitored and the comparison between the hot water temperature T and the immediate hot water operation start temperature T1 is continued. When the hot water temperature T in the pipe is gradually lowered to the hot water operation start temperature T1 or lower, the operation of the circulation pump 14 is started (S23). At this time, since the bypass flow rate servo valve 13 has the opening degree in the last hot water supply use state, when the circulation pump 14 is operated, the high temperature hot water remaining in the hot water supply pipe 3b from the heat exchanger 4 to the bypass passage connection point is maintained. The hot water is mixed with the water remaining in the bypass passage 7, becomes almost equal to the hot water supply set temperature at the time of the last use, and is sent to the downstream side of the bypass passage connection point of the hot water supply pipe 3b. 3b → hot water supply return pipe 8 → water supply pipe 3a (heat exchanger 4) or bypass passage 7 → hot water supply pipe 3b.

In the above-mentioned conventional example, since the bypass passage 7 is fully closed when the circulation pump 14 is in operation, when the hot water tap 6 is opened immediately after the circulation pump 14 is operated, the heat exchanger 4 is opened.
The high-temperature hot water remaining inside was discharged from the hot water tap 6 through the hot water supply pipe 3b as it was, which was dangerous. In contrast,
In the present invention, when the operation of the circulation pump 14 is started,
Since the bypass flow rate servo valve 13 has not been closed yet, even if the hot water tap 6 is opened immediately after the circulation pump 14 is operated, the hot water remaining in the heat exchanger 4 and the water in the bypass passage 7 will remain. The hot water is mixed in the hot water supply pipe 3b and discharged from the hot water tap 6 as safe hot water having a proper temperature.

After the operation of the circulation pump 14 is started, if the hot water tap 6 is not opened, the control unit 2 fully closes the bypass flow rate servo valve 13 after a lapse of a certain time (S24), and the hot water in the pipe passes through the bypass passage 7. Prevent short pass through,
The entire circulating flow rate is passed through the heat exchanger 4 to ensure a minimum operating flow rate (MOQ) determined by the minimum capacity limit of the gas burner. In other words, the hot water in the pipe must be the hot water supply pipe 3b →
The hot water supply return pipe 8-> the water supply pipe 3a-> the heat exchanger 4-> the hot water supply pipe 3b circulates in a route to accurately control the temperature.

When the bypass flow rate servo valve 13 is fully closed, the hot water in the heat exchanger 4 has already been mixed with the water in the bypass passage 7 to be a proper temperature water, so that the hot water tap 6 is opened. There is no danger of hot water being discharged from the hot water tap 6.

When the hot water circulates in the pipe in this way, the flow rate of the hot water flowing through the heat exchanger 4 is monitored by the water amount sensor 9 to determine whether the flow rate is equal to or higher than the minimum operating flow rate (S25). If this flow rate is less than or equal to the minimum operating flow rate, it is determined that an abnormality has occurred, and the hot water operation is interrupted or an abnormality is reported to take an abnormal action. When it is confirmed that the flow rate is equal to or higher than the minimum operating flow rate, the gas burner 17 is ignited to control the hot water temperature in the pipe (S26). Then, the hot water temperature T in the pipe is compared with a predetermined instant hot water operation end temperature T2 (> T1) (S27), and the hot water temperature T
If the temperature does not reach the immediate hot water operation end temperature T2, the process returns to step S25 to recheck whether the flow rate is equal to or lower than the minimum operating flow rate. In this way, steps S25 to S27 are repeated until the hot water temperature T reaches the immediate hot water operation end temperature T2, and when the hot water temperature T in the pipe monitored by the temperature sensor 15 becomes equal to or higher than the immediate hot water operation end temperature T2, the gas burner The combustion of 17 is stopped (S28), the circulation pump 14 is post-operated for a certain period of time to make the distribution of the hot water temperature in the pipe uniform, and then stopped (S29, 30). After the circulation pump 14 is stopped, it is monitored again whether the hot water temperature T is equal to or lower than the immediate hot water operation start temperature T1 (S22), and when the hot water temperature T has dropped to the immediate hot water operation start temperature T1, the above is performed. As described above, the flow from step 22 onward is repeated.

As a result of the above processing, hot water having a temperature equal to or higher than the immediate temperature operation start temperature T1 and equal to or lower than the immediate temperature operation end temperature T2 is always stored in the pipe, and when a hot water tap such as a calan is opened, a desired comfortable temperature is immediately obtained. No hot water is discharged.

The instant hot water operation start temperature T1 and the instant hot water operation end temperature T2 may be constant values regardless of the set temperature Ts.

[0027]

According to the present invention, when the circulation pump for immediate hot water operation is started while the hot water tap is closed, the hot water in the heat exchanger and the water in the bypass passage flow into the hot water supply circuit. Since they are mixed, it is possible to prevent a hot water region from being generated in the hot water supply circuit. Therefore, even if the hot water tap is opened immediately after the start of the hot water operation, there is no danger of hot water coming out of the hot water tap, and the safety of the hot water supply device with the instant hot water function can be enhanced.

Further, after a certain period of time has passed after the operation of the circulation pump, the flow rate adjusting valve in the bypass passage is fully closed.
The hot water in the pipe can be prevented from short-circuiting through the bypass passage without passing through the heat exchanger, and the hot water in the pipe can be reliably heated or kept warm.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a hot water supply device having an immediate hot water function according to an embodiment of the present invention and a conventional example.

FIG. 2 is a block circuit diagram showing a configuration for immediate hot water operation control in one embodiment of the present invention.

FIG. 3 is a flowchart illustrating a control method of the hot water operation control unit of the above.

FIG. 4 is a flowchart illustrating a method for controlling the hot water supply device of FIG. 1 according to a conventional example.

[Explanation of symbols]

 2a Immediate hot water operation control unit 3 Hot water supply circuit 4 Heat exchanger 6 Hot water tap 7 Bypass passage 8 Hot water return pipe 13 Bypass flow rate servo valve 15 Temperature sensor 17 Gas burner 18 Capacity control device

Claims (1)

[Claims] 1. A hot water supply passage having a heat exchanger, a heating device for heating the heat exchanger, a bypass passage connected to the hot water supply passage so as to bypass the inlet side and the outlet side of the heat exchanger, and a bypass passage. , A hot water supply return pipe connected between the hot water supply passage near the hot water tap and the heat exchanger inlet side of the hot water supply passage, a circulation pump for circulating hot water through the hot water supply return pipe, and a hot water return pipe A hot water temperature detector that detects the temperature of hot water circulating through the hot water, and an immediate hot water operation control unit that circulates the hot water by operating the circulation pump while the hot water supply is stopped to keep the temperature of the hot water within a predetermined range In a hot water supply device with an immediate hot water function, after the operation of the circulation pump is started by the immediate hot water operation control unit,
A hot water supply device characterized in that the flow control valve in the bypass passage is fully closed after a certain time has elapsed.