JP3140958B2 - Gas 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 an instantaneous gas water heater for use in kitchens, baths, floor heaters, etc., which starts heating by a gas burner simultaneously with the start of hot water supply.

[0002]

2. Description of the Related Art Generally, there are known gas water heaters of a hot water storage type in which hot water heated to a predetermined temperature is stored and an instantaneous type in which heating by a gas burner is started simultaneously with the start of hot water supply. Since the hot water storage type gas water heater stores hot water at a predetermined temperature in a tank, it has the advantage of being able to use heated hot water without delay.On the other hand, the equipment is large and the installation conditions are limited. There is a problem that there are many. On the other hand, instantaneous gas water heaters are widely used because they do not need to store hot water, are small in size, and are easy to install.

[0003]

On the other hand, in the instantaneous gas water heater, when the hot water supply is stopped, the temperature of the water (hereinafter, referred to as retained water) staying in the water heater gradually decreases, and the retained water is stopped. If the temperature is lowered to some extent, the time required to heat the retained water to a desired temperature becomes longer. In other words, a time delay occurs not only by the length of the pipe from the gas water heater to the curan until the hot water of the desired temperature reaches the curan, but a relatively long time is required until the temperature of the hot water discharged from the curan rises. It will cost you.

[0004] In particular, when the time from when the hot water is stopped to when it is discharged again is relatively short, the temperature drop of the retained water is relatively small, but the time from the stop of hot water supply to the restart of hot water supply is reduced. If the temperature is long, the temperature of the retained water drops significantly,
As a result, the time delay until the temperature of the hot water sent from the water heater rises greatly increases. As a solution to this kind of problem, for example, as shown in FIG.
Hot water supply pipe 6 to which curran 5 for discharging hot water from
In addition to the above, it is conceivable to provide a return pipe 7 from a terminal of the hot water supply pipe 6 to the water heater 1 and to circulate hot water supplied from the water heater 1 to the water heater 1 through a path from the hot water supply pipe 6 to the return pipe 7. ing. In other words, by providing a circulation path by the hot water supply pipe 6 and the return pipe 7, the hot water continues to flow even while the curran 5 is closed, the temperature of the circulating hot water is monitored by the water heater 1, and the circulation path The hot water is appropriately heated in the water heater 1 so that the temperature of the hot water passing through the hot water is maintained at a predetermined temperature.

If this configuration is adopted, the temperature of the hot water passing through the circulation path is maintained at a predetermined temperature, so that the hot water can be discharged while the curran 5 is opened.
Further, when the curran 5 is opened, the gas burner of the water heater 1 is ignited, so that the hot water can be continuously discharged. In this way, if the configuration shown in FIG. 8 is adopted, there is almost no time delay from the opening of the curran 5 to the rise of the temperature of the hot water to be discharged, but since the return pipe 7 is provided, the construction is It is troublesome and difficult to install in an existing building. In addition, in order to circulate hot water in a circulation path formed by the hot water supply pipe 6 and the return pipe 7, it is necessary to provide a circulating device such as a pump in the water heater 1, and the configuration of the water heater 1 becomes complicated. And increase costs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to maintain the temperature of retained water even after the stop of hot water supply, and to increase the rise time from the start of hot water supply until the hot water reaches a desired temperature. To provide a gas water heater with a reduced length.

[0007]

According to the first aspect of the present invention, there is provided a heat exchanger for heating introduced water with a gas burner, a heating temperature detector for detecting a temperature of water at an outlet side of the heat exchanger, and a heat exchanger. A flow sensor for detecting a flow rate of water passing through the exchanger, control means for starting supply of fuel gas to the gas burner and igniting the gas burner when a flow rate detected by the flow sensor becomes a predetermined value or more ; Fuel gas
Variable to adjust the flow rate of fuel gas
A flow valve, and a plurality of valves corresponding to each part of the heat exchanger.
When the flow rate detected by the flow rate sensor falls below a predetermined value , the control means obtains a reheating temperature that is a predetermined temperature difference from the temperature detected by the heating temperature detector, and detects the heating temperature. When the temperature detected by the heater drops to the reheating temperature, a heat retention process for igniting the gas burner for a heating time determined based on the heating amount required for the temperature increase of the temperature difference and the heating capacity of the gas burner is performed.
, All gas burners are ignited simultaneously
And the fuel gas flow rate is the minimum flow rate allowed
The variable gas flow valve is adjusted as described above .

[0008] According to this configuration, after the hot water supply is stopped, the retained water retained in the water heater is kept warm.
In the heat retention process, if the temperature detected by the heating temperature detector provided on the outlet side of the heat exchanger drops to the reheating temperature obtained based on the heating temperature detector at the time of stopping hot water supply, the temperature can be increased to the temperature at the time of stopping hot water supply Since the stored water is heated by igniting the gas burner for an appropriate amount of time, the temperature of the stored water can be maintained within a predetermined range. As a result, even when the hot water supply is restarted after stopping the hot water supply for a long time, the rising time of the hot water temperature is short, and the usability is improved. Also, since there is no change in the configuration of the conventional water heater and only the control procedure of the control means is changed, it is possible to provide the conventional product without increasing the price.

[0009]

Furthermore, since the number of gas burners to be ignited can be selected, the variable range of the amount of heating by the gas burners is wide, and the restriction on the relationship between the temperature of the introduced water and the temperature of the supplied hot water is reduced. Moreover, since all the gas burners are ignited during the heat retaining process , the water in the heat exchanger can be heated uniformly, and the temperature distribution in the heat exchanger does not become uneven. Since the flow rate of the fuel gas is set so as to be the minimum flow rate allowed in the state in which the fuel gas is ignited, it is difficult to overheat even if there is some error in the heating time.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a basic configuration. The housing 2 of the water heater 1 is provided with a water supply port 11 for introducing water supplied by city water or the like, a water supply port 12 for sending out hot water heated by the water heater 1, and a fuel gas supply port. A gas inlet 13 for introduction is provided. The housing 2 houses a heat exchanger 22 for heating water introduced through the water supply port 11 by a gas burner 21.
On a flow path from the water supply port 11 to the heat exchanger 22, a water supply temperature detector 23 composed of a thermistor and a flow sensor 24 that measures the flow rate of water introduced into the heat exchanger 22 through the water supply path are provided. Be placed. A heating temperature detector 25 composed of a thermistor and a variable flow valve 2 for adjusting the flow rate of hot water in accordance with a control signal from a microcomputer 20 described later are provided on a flow path from the heat exchanger 22 to the tap hole 12.
6 and a tapping temperature detector 27 composed of a thermistor for detecting the temperature of tapping water sent from tapping port 12 are provided. Further, the connection between the feedwater temperature detector 23 and the variable flow valve 26 is also established by the bypass pipe 14,
4 is provided with a bypass valve 28. The variable flow valve 26 is an electromagnetic valve or a motor-operated valve capable of adjusting a flow rate in a plurality of stages, and an electromagnetic valve is used as the bypass valve 28. Although not shown, a pressure relief valve for releasing the pressure when the pressure of the heat exchanger 22 rises is provided.

A supply path of the fuel gas to the gas burner 21 includes a gas on-off valve 15 composed of an electromagnetic valve for selecting supply and cutoff of the fuel gas by a control signal from a microcomputer 20 described later, and a microcomputer 20 described later. And a gas variable flow valve 16 composed of an electromagnetic valve or an electric valve that adjusts the flow rate of the fuel gas in a plurality of stages in accordance with a control signal from the controller. Further, two or three gas burners 21 are provided so that the number of the burners can be controlled in accordance with the hot water supply amount, and an opening / closing valve 17 is inserted in a supply path of the fuel gas to the gas burners 21. Therefore, if all the gas burners 21 are ignited, the amount of heating can be increased. For example, when the on-off valve 17 is closed and one gas burner 2
If only one fuel gas is supplied, the heating amount can be reduced. That is, the gas variable flow valve 16 and the on-off valve 17
By using in combination, the amount of heating can be adjusted over a wide range. Although not shown, when the gas on-off valve 15 is opened, the gas burner 21 is opened.
Is started.

As shown in FIG. 2, the variable flow valve 26, the bypass valve 28, the gas on / off valve 15, the gas variable flow valve 16 and the on / off valve 17 are provided with a microcomputer 20 as control means housed in the housing 2. Is controlled by A remote control device 30 is connected to the microcomputer 20 via a connection line 29. The remote control device 30 includes an operation switch 31 for instructing the operation of the water heater 1 and a temperature setting unit 32 for setting the temperature of the hot water to be sent out. The water supply temperature detector 23, the heating temperature detector 25, and the tap water temperature detector 27
The gas on-off valve 15, the gas variable flow valve 16, the on-off valve 17, and the variable flow valve 2 are set so that the temperature of the hot water to be sent approaches the hot water supply temperature set by the temperature setting unit 32 based on the detected temperature at
6. Control the bypass valve 28.

Next, the operation during operation will be described with reference to FIG. When the operation is started, first, the hot water supply temperature set by the remote control device 30 is read (S1), and the passing flow rate detected by the flow rate sensor 24 is read (S1).
2). If the passing flow rate is equal to or less than the predetermined value (S3), the gas on-off valve 15 is kept closed. On the other hand, when the flow rate detected by the flow rate sensor 24 is equal to or more than the predetermined value, the gas on-off valve 15 is opened and the gas burner 21 is ignited (S4).
The calorie of the gas burner 21 is determined based on the difference between the temperature detected by the water supply temperature detector 23 and the hot water temperature set by the remote controller 30 and the flow rate detected by the flow rate sensor 24, and the gas variable flow rate is determined so that the heat quantity is obtained. The opening amount of the valve 16 is adjusted, and the on-off valve 17 is controlled as necessary (S5). At this time, the heat quantity of the gas burner 21 is set so that the temperature of the hot water detected by the heating temperature detector 25 becomes higher than the hot water supply temperature, and the hot water discharged from the heat exchanger 22 by opening the bypass valve 28. The desired hot water temperature is obtained when the water and the water introduced through the water supply port 11 are mixed. Further, since the temperature of the hot water to be sent out may not match the hot water supply temperature only by adjusting the gas variable flow valve 16, the gas variable flow valve may be adjusted so that the temperature detected by the tapping water temperature detector 27 and the hot water supply temperature match. The opening amount of the valve 16 is corrected (S6). Further, when the gas variable flow valve 16 alone cannot cope with the situation, the tapping amount is controlled by the variable flow valve 26. Thereafter, the flow rate is detected by the flow rate sensor 24 (S7). If the flow rate decreases (S8), the gas burner 21 is extinguished (S9).

By the way, in this type of water heater 1, the tap 1
When the discharge of hot water was stopped after discharging 10 liters of 40 ° C. water per minute from 2 to 5 m ahead, 5 minutes from the stop
It is desired that the temperature is kept within ± 3 ° C. with respect to the hot water supply temperature set by the remote control device 30 within minutes.
For example, in the case of washing dishes, the use of hot water is stopped once and the hot water is often reused after a short time. In such a usage form, the temperature of the discharged hot water fluctuates.
If you do not reduce the temperature change when reusing hot water,
A so-called sandwich phenomenon in which hot water and cold water are discharged alternately occurs, giving the user discomfort.

In order to suppress such a sandwich phenomenon, in the present embodiment, the time from the ignition of the gas burner 21 to the opening of the bypass valve 28 is adjusted according to the temperature detected by the heating temperature detector 25. I have to.
That is, as shown by the broken line in FIG. 4, the temperature of the water inside the heat exchanger 22 decreases with the passage of time.
In order to suppress a decrease in the temperature of the hot water sent out from the furnace, the amount of cold water mixed through the bypass pipe 14 may be reduced. Therefore, by adjusting the timing from the ignition of the gas burner 21 to the opening of the bypass valve 28, the change in the temperature of the hot water sent from the tap 12 as shown by the solid line in FIG. 4 is reduced. At the same time, the variable flow valve 26 is also controlled, and the temperature of the hot water is suppressed by the gas variable flow valve 16 while reducing the amount of hot water to be sent out from the tap hole 12. With such control,
Even if the tapping and stopping are repeated, it is possible to reduce fluctuations in the temperature of the tap water sent out from tap hole 12.

Since the temperature of the water retained in the heat exchanger 22 is maintained at a sufficiently high temperature for a relatively short time of about 5 minutes, even if the above-described control is performed, the water supply is stopped. After a long time, it takes time for the temperature of the hot water to rise 5 m ahead. Thus, in the present embodiment, the warming-up process (S10) is performed after the hot water supply is stopped, thereby shortening the rise time of the hot water temperature.

In the heat retention process, as shown in FIG. 5, the heating temperature detected by the heating temperature detector 25 at the time when the hot water supply is stopped and the gas burner 21 is extinguished is read (S11), and the temperature is lowered by a predetermined temperature difference. The temperature is determined as the reheating temperature (S12). Further, a heating time required to heat the water retained in the heat exchanger 22 from the reheating temperature to the temperature detected at the time of extinguishing the gas burner 21 is determined (S13). That is, the amount of heating required to raise the temperature by the difference between the temperature of water at the time of stopping hot water supply and the reheating temperature (the above-described predetermined temperature difference) is determined, and the heating required to heat the determined amount of heating is determined. The time is determined based on the heating capacity of the gas burner 21. When the gas burner 21 extinguishes, the temperature of the water retained in the heat exchanger 22 (that is, the temperature detected by the heating temperature detector 25) gradually decreases. Therefore, the heating temperature is read (S14) and compared with the reheating temperature (S14).
15) When it is detected that the heating temperature detected by the heating temperature detector 25 has decreased to the reheating temperature, the gas on-off valve 15 is opened to ignite the gas burner 21 (S1).
6). After the gas burner 21 is ignited for the above-described heating time (S19) and is extinguished (S20), the heat exchanger 2
The temperature of the retained water inside 2 is maintained at a temperature between the temperature at the time of stopping the hot water supply and the reheating temperature. During operation of the water heater 1, the gas burner 21 is ignited each time the temperature of the water held in the heat exchanger 22 decreases to the reheating temperature. Will be ignited intermittently. Gas burner 21
When the hot water supply is resumed during the ignition of the
(S17, S18), the flow returns to step S1 in FIG.

When the gas burners 21 are ignited for the heating time obtained as described above, all the gas burners 21 are ignited simultaneously, and the flow rate of the fuel gas is set to the minimum flow rate permitted by the gas variable flow valve 16. I do. Therefore, the heating time t is equal to the heating amount Q and the heat amount Qu per unit time given to the water retained inside the heat exchanger 22 when the entire gas burners 21 are ignited to the minimum flow rate.
And can be obtained in the form of t = Q / Qu. Further, the heating amount Q can be obtained in the form of Q = V · ΔT based on the capacity V of the heat exchanger 22 and the predetermined temperature difference ΔT.

As shown in FIG. 6, the hot water supply is stopped at time t ₀ ,
If the heating temperature detected by the heating temperature detector 25 at this time is 70 ° C., depending on the season and heat capacity, for example, the temperature drops to about 60 ° C. after a lapse of 10 minutes from time t _0. . Here, if it is assumed that the temperature difference ΔT is set to 10 ° C., the heating amount is obtained when the heating temperature detected by the heating temperature detector 25 reaches 60 ° C., and the gas burner 21 is re-ignited. Because Now, assuming that the capacity of the heat exchanger 22 is 1.5 liters, the heating amount Q
Is 1.5 × 10 = 15 kcal, so gas burner 2
Assuming that the amount of heat Qu given to the water held in the heat exchanger 22 per unit time from 1 is 3.5 kcal, the heating temperature t is 15 ÷ 3.5 ≒ 4 seconds. That is, if the gas burner 21 is ignited for 4 seconds, the temperature of the water held in the heat exchanger 22 becomes approximately 70 ° C. As described above, the temperature of the water retained in the heat exchanger 22 can be maintained at 60 to 70 ° C., and relatively high-temperature hot water can be discharged even 5 m away from the water heater 1 without delay. You can do it.
Here, the outlet side of the heat exchanger 22 is arranged so as to be higher than the inlet side, and the heating temperature detector 25 detects the higher temperature of the water held in the heat exchanger 22.

The amount of heat per unit time at the time of ignition of the gas burners 21 can be adjusted by the gas flow valve 16 and the on-off valve 17, but in the present embodiment, the minimum allowable value in a state where all the gas burners 21 are ignited. (The minimum supply amount of fuel gas). As described above, by igniting all the gas burners 21 at the same time, the water held in the heat exchanger 22 can be uniformly heated so that the temperature distribution does not become uneven. In addition, the larger the heat quantity of the gas burner 21, the shorter the heating time can be. However, since the heating time t is determined as described above, the heat quantity per unit time is large. Overheating can occur. On the other hand, the amount of heat per unit time is
By setting the minimum value at which the holding water of No. 2 can be heated uniformly, the possibility of overheating can be greatly reduced.

FIG. 7 shows the temperature change of hot water when the conventional configuration and the configuration of the present embodiment are used for a shower.
7A and 7B show the temperature of the hot water at the hot water supply port 12 of the water heater 1, and C and D show when 10 liters of hot water is discharged per minute from the outlet of the shower 5 m away from the hot water supply port 12. Shows the temperature of hot water. A broken line indicates a conventional configuration, and a solid line indicates the present embodiment. Time t ₁ indicates a time point 5 minutes after the stop of hot water supply, and time t ₂ indicates a time point at which discharge of hot water from the shower is restarted. As is clear from FIG.
Even after the hot water supply is stopped, the temperature of the retained water inside the heat exchanger is kept higher in the present embodiment than in the conventional configuration.
Also by this, when it resumes hot water supply to the time t _2, the variation width of the temperature of the hot water discharged from the shower is small. This is because, in the conventional configuration, when the discharge of hot water from the shower is resumed, the temperature of the water retained inside the heat exchanger 22 has dropped, so that low-temperature hot water is discharged first. Due to the large difference between the temperature of the retained water inside the exchanger 22 and the target temperature, the gas burner 21
Overheating occurs due to rapid heating of the retained water by increasing the heat quantity of the water. On the other hand, in the present embodiment, the temperature of the retained water inside the heat exchanger 22 is kept relatively high, so that when the discharge of the hot water from the shower is restarted, the low-temperature hot water is discharged. In addition, the amount of heat of the gas burner 21 is relatively small, and overshoot hardly occurs. By the way, when the discharge of hot water from the shower is resumed, the time until the temperature of the hot water is settled is about 10 seconds shorter in the present embodiment than in the conventional configuration. In the case of the embodiment, the temperature was about 3.5 ° C., whereas that of the conventional configuration was about 10 ° C.

In the above-described embodiment, the method of controlling the opening timing of the bypass valve 28 has been described as an example of the temperature control method when the hot water supply is repeatedly stopped and restarted during operation. However, the present invention is not limited to this. Instead, other similar techniques can be used. Further, it may be possible to select whether or not to perform the heat retaining process by adding a heat retaining switch to the remote control device 30. A heat retaining switch may be provided separately from the operation switch 31 and the temperature setting unit 32, or the operation switch 31 and the temperature When the setting unit 32 is operated at the same time, it is possible to function as a heat retaining switch. When it is possible to select whether or not to perform the heat retaining process, a predetermined time (for example, 4 hours) after the hot water supply is stopped so that the heat retaining process is not unnecessarily continued.
When the hot water supply is not resumed within the time period, it is desirable to cancel the heat retaining process.

[0024]

According to the first aspect of the present invention, after the hot water supply is stopped, the retained water retained in the water heater is kept warm, and the heating temperature detector provided at the outlet side of the heat exchanger is used in the warm kept processing. When the detected temperature at the time drops to the reheating temperature determined based on the heating temperature detector at the time of stopping hot water supply, the gas burner is ignited for the time that can be raised to the temperature at the time of stopping hot water supply, and the retained water is heated. There is an advantage that the temperature of the retained water can be kept within a predetermined range. As a result, even when the hot water supply is restarted after the hot water supply is stopped for a long time, there is an effect that the rise time of the hot water temperature is short, and the usability is improved. In addition, there is no change in the configuration of the conventional water heater, and only a change is made to the control procedure by the control means. Therefore, there is an advantage that it is possible to provide the conventional product without increasing the price. is there.

Further, a plurality of gas burners are provided in association with each part of the heat exchanger, and a gas variable flow valve for adjusting a flow rate of the fuel gas is disposed on a flow path of the fuel gas to the gas burner. fuel with but simultaneously ignite all the gas burner in the heat retaining, and there is for adjusting the gas variable flow rate valve so as to minimize flow rate of the fuel gas is allowed to ignite incubated process sometimes all gas burners at the same time The gas variable flow valve is adjusted so that the flow rate of the gas is the minimum flow rate allowed.The number of gas burners to be ignited can be selected. There is an advantage that the restriction on the relationship between the temperature and the temperature of the hot water to be sent out is reduced. Moreover, since all the gas burners are ignited during the heat retaining process , the water in the heat exchanger can be uniformly heated, and the temperature distribution does not become uneven in the heat exchanger. In addition, since the flow rate of the fuel gas is set so as to be the minimum flow rate allowed when all gas burners are ignited, there is an effect that it is difficult to overheat even if there is some error in the heating time. is there.

[Brief description of the drawings]

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

FIG. 2 is a main part block diagram of the same.

FIG. 3 is an operation explanatory diagram of the above.

FIG. 4 is an operation explanatory view of the above.

FIG. 5 is an operation explanatory diagram showing a heat retaining process according to the first embodiment;

FIG. 6 is an operation explanatory view of the above.

FIG. 7 is a diagram showing an operation example of the above.

FIG. 8 is a schematic configuration diagram showing a conventional example.

[Explanation of symbols]

 Reference Signs List 15 gas on-off valve 16 gas variable flow valve 17 on-off valve 20 microcomputer 21 gas burner 22 heat exchanger 23 feedwater temperature detector 24 flow sensor 25 heating temperature detector

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F24H 1/10 302 F23N 5/00

Claims (1)

(57) [Claims] 1. A heat exchanger for heating introduced water by a gas burner, a heating temperature detector for detecting a temperature of water at an outlet side of the heat exchanger, and a flow rate of water passing through the heat exchanger. a flow sensor, and control means to ignite the gas burner with flow rate detected by the flow sensor to start the supply of fuel gas to the burner becomes a predetermined value or more, gas
Fuel gas flow rate located on the fuel gas flow path to the burner
And a variable gas flow valve for adjusting the temperature of each part of the heat exchanger.
A plurality of gas burners are provided in association with the control unit , and the control unit performs reheating, which is a predetermined temperature difference with respect to the temperature detected by the heating temperature detector when the flow rate detected by the flow rate sensor becomes less than a predetermined value. When the temperature is determined and the temperature detected by the heating temperature detector falls to the reheating temperature, the heat retention process ignites the gas burner for the heating time determined based on the heating amount required for the temperature rise of the temperature difference and the heating capacity of the gas burner. And all gases in the heat treatment
Simultaneously ignite the burners and allow fuel gas flow
Gas water heaters, wherein the this <br/> to adjust the gas variable flow rate valve so as to minimize flow rates.