JPH06159671A - Controlling method for combustion of hot-water supplying apparatus - Google Patents

Abstract

PURPOSE:To stabilize a hot water temperature at the time of outputting hot water by supplementing a backup heat quantity by intermittent combustion. CONSTITUTION:When combustion is stopped after a hot-water supplying apparatus is used, a post-heating quantity in a heat exchanger is obtained by calculation of a post-heating quantity calculator 26. Then, a standby time required for lowering the post-heating hot-water temperature to a lower limit operating temperature is set by a standby time setter 29 based on heat dissipating conditions of the exchanger. After the combustion is stopped, when this standby time is elapsed, a hot-water temperature in the exchanger is lowered to the lower limit operating temperature. In this case, intermittent combustion is conducted by a backup heat quantity necessary to raise the hot-water temperature up to a heating upper limit temperature. Thus, the hot-water temperature in the exchanger is always held in a range of an upper limit allowable temperature and a lower limit allowable temperature of the set temperature. Thus, when hot water is then output, hot water of a temperature substantially near the set temperature can be output from a water cock, and hot water user can use the hot water with comfortableness.

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 combustion control method for stabilizing the hot water temperature at the time of initial hot water discharge of the hot water heater.

[0002]

2. Description of the Related Art When the combustion is stopped after the water heater is used, the hot water in the heat exchanger is gradually cooled. After the hot water in the heat exchanger cools down, the hot water with a temperature considerably lower than the set temperature for hot water supply first comes out, and then the hot water comes out by the combustion heat of the heat exchanger. There is a problem that the users of the hot water feel uncomfortable due to variations in the hot water temperature.

In order to solve such a problem, recently, various methods have been taken to stabilize the temperature of hot water when the hot water is discharged from the water heater. One of them is to delay the fire extinguishing timing a little at the end of use of the water heater, close the faucet, and then, without stopping the combustion immediately, continue combustion for a short time to heat the heat exchanger, The temperature of the hot water in the exchanger is increased to allow time for the hot water to cool down after the combustion is stopped, and when the hot water is discharged next, the hot water as close as possible to the preset temperature is discharged.

Another method for stabilizing the hot water temperature is to provide an auxiliary pilot burner for locally heating the heat exchanger in addition to the main burner for heating the heat exchanger. After the combustion is stopped, the pilot burner is continuously burned for a predetermined short time to prevent the temperature of the hot water in the heat exchanger from decreasing, and when the hot water is discharged next time, the hot water with the temperature as close as possible is discharged. It is the one.

[0005]

However, the method of delaying the fire extinguishing timing of the burner after the faucet is stopped is shown in FIG.
As shown by the curve A in FIG.
If the temperature of the hot water in the heat exchanger exceeds the upper limit allowable temperature for the set temperature and is overheated, and if the faucet is opened again to drain hot water immediately after closing the faucet, there is a problem that hot water comes out. , Even if the temperature of hot water in the heat exchanger is increased by delaying the fire extinguishing timing, if the hot water supply stop time becomes long, the temperature of the hot water in the heat exchanger gradually cools down below the lower limit allowable temperature of the set temperature. There is a problem that the hot water temperature becomes low, and it becomes impossible to stabilize the hot water temperature when the hot water is discharged from the water heater.

Further, in the method of burning the pilot burner for a predetermined short time after the main burner has stopped burning, the heating energy of the pilot burner is small as shown by the curve B in FIG. By this, it is possible to prevent the hot water temperature in the heat exchanger from becoming higher than the upper limit allowable temperature of the set temperature, but since the heat exchanger is locally heated,
There is a problem that the hot water in the heat exchanger has uneven temperature and stable hot water cannot be discharged. Also, in the method using the pilot burner, after the pilot burner extinguishes, the hot water temperature in the heat exchanger is gradually cooled and falls below the lower limit allowable temperature of the set temperature, so stable hot water close to the set temperature is discharged. There is a problem that you can not do it.

The present invention has been made in order to solve the above-mentioned conventional problems, and an object thereof is to stabilize the hot water temperature when hot water is discharged again after a long time has elapsed after the hot water supply has been stopped. It is an object of the present invention to provide a combustion control method for a water heater capable of discharging hot water.

[0008]

In order to achieve the above object, the present invention is constructed as follows. That is, the method of the present invention calculates the post-boiling amount of hot water in the heat exchanger from the hot water supply operating conditions before the combustion is stopped each time the hot water supply is stopped, and then the heat radiation conditions after the combustion is stopped. Based on this, the temperature of the post-boiling water is the lower limit operating temperature set within the lower limit allowable temperature range of the set temperature or the waiting time after combustion stop required to decrease to the temperature corresponding to this temperature, and the lower limit operating temperature or this By calculating the temperature corresponding to the temperature, the predetermined heating upper limit temperature determined within the upper limit allowable temperature range of the set temperature, or the backup heat amount required to raise the hot water temperature in the heat exchanger to the temperature corresponding to this temperature. The ignition is performed every time the standby time elapses after the combustion is stopped, and the intermittent combustion for supplementing the backup heat amount is performed.

[0009]

In the present invention having the above-mentioned structure, when the post-use combustion of the water heater is stopped, the amount of post-boiling of the hot water in the heat exchanger is calculated, and then the temperature of the post-boiling water is set to the lower limit operation. The waiting time required to decrease to the temperature (or the temperature corresponding to this temperature) is calculated by calculation based on the heat radiation condition of the heat exchanger. When this waiting time elapses after the combustion is stopped, the hot water temperature in the heat exchanger drops to the lower limit operating temperature (or the temperature corresponding to this temperature), but at this time, the heating upper limit temperature (or the temperature corresponding to this temperature). Since intermittent combustion is performed by the amount of backup heat required to raise the hot water temperature up to), the hot water temperature in the heat exchanger is always the upper and lower limit allowable temperatures of the set temperature (or the temperatures corresponding to these temperatures). ), The next time the hot water is discharged, the hot water of about the set temperature can be discharged from the faucet, and the user of the hot water feels uncomfortable due to fluctuations in the hot water temperature. You can use the hot water comfortably.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 shows a system example of a water heater to which the method of the present invention is applied. (A) of the figure shows a system example of a combined water heater, and (b) of the figure shows a single-function water heater. Each system example is shown. The combined water heater of (a) of the figure is
A hot water supply heat exchanger 1 and a bath heat exchanger 2 are provided together, a hot water supply burner 3 is provided on the hot water supply heat exchanger 1 side, and a gas amount detection sensor for detecting a gas flow rate is provided in a gas passage of the hot water supply heat burner 3. 4 are provided.

A water supply pipe 5 is connected to the inlet side of the hot water supply heat exchanger 1, and a water supply temperature sensor 6 such as a thermistor for detecting the water supply temperature and a flow sensor 7 for detecting the water supply flow rate are connected to the water supply pipe 5. And are provided. A hot water supply pipe 8 is connected to the outlet side of the hot water supply heat exchanger 1, and a faucet 25 is provided on the outlet side of the hot water supply pipe 8. Further, the hot water supply pipe 8 is provided with a hot water temperature sensor 10 for detecting the hot water temperature. A bypass passage 11 is provided in parallel in the hot water supply heat exchanger 1 (the bypass passage 11 may be omitted in some cases).

A bath burner 12 is provided on the bath heat exchanger 2 side so that the bath heat exchanger 2 can be reheated and heated. One end of the pipe 13 is connected to the inlet side of the bath heat exchanger 2, and the other end of the pipe 13 is connected to the discharge side of the circulation pump 14. The outlet side of the return pipe 16 of the reheating circulation pipe 15 is connected to the suction side of the circulation pump 14, and the inlet side (return port side) of the return pipe 16 is connected to the bath 17. Also,
On the outlet side of the bath heat exchanger 2, the forward line of the reheating circulation line 15
The inlet side of 18 is connected, and the outlet side of the outgoing pipe 18 is connected to the bathtub 17.

The reheating circulation pipe line 15 and the hot water supply pipe 8 are communication pipes 20.
A pouring solenoid valve 21 is interposed in the communication pipe 20. Further, the hot water supply heat exchanger 1 and the bath heat exchanger 2 are supplied with air for supply and exhaust air from separate or common fans, or in FIG. 3A, a common fan 22. The fan 22 is provided with a fan rotation detection sensor 9, and an outside air temperature detection sensor (outside air temperature thermistor) 19 for detecting intake air temperature is provided around the fan 22.

The hot water supply operation and the bath reheating operation of this kind of equipment are controlled by the control device 23. This controller
A remote controller 24 is connected to the remote controller 23, and the remote controller 24 is provided with a button for setting a set temperature of hot water and a set temperature display section.

The system of the single-function water heater shown in FIG. 3 (b) is obtained by omitting the system on the bath side shown in FIG. 3 (a). , The flow of water entering the hot water supply heat exchanger 1 is the flow sensor 7
In response to the signal from the flow sensor 7, the control device 23 performs gas supply and ignition operation by an igniter electrode (not shown), burns the hot water supply burner 3 and passes water through the hot water heat exchanger 1. Is heated to hot water, and this hot water is discharged from the faucet 25 through the hot water supply pipe 8. Then, when the flow sensor 7 stops detecting the flow of water by closing the faucet 25, the control device 23 receives the OFF signal from the flow sensor 7 and stops the combustion of the hot water supply burner 3.

FIG. 1 shows an embodiment of a combustion control section of a control device 23 for stabilizing the hot water temperature when the hot water is discharged from the water heater. This combustion control unit includes a post-boiling amount calculation unit 26, a heat radiation amount calculation unit 27, a backup heat amount calculation unit 28, a standby time setting unit 29, a combustion time calculation unit 30, a timer 31, and a combustion control unit 32. And is configured. Post-boiling amount calculator 26
When the combustion of the water heater is stopped, is the amount of after-boiling (after-boiling) Is a phenomenon in which the amount of heat retained in the hot water supply heat exchanger is transferred to the internal hot water after the combustion is stopped, and the temperature of the hot water rises) is calculated by the amount of heat or the value of the post-boiling temperature of the hot water in the heat exchanger.
In this calculation, a calculation formula obtained by experimentally correcting the theoretical formula is used.

The heat radiation amount calculation unit 27 obtains the heat radiation amount as a function of time by using a given calculation formula based on the intake air temperature of the fan 22, the capacity of the fan (fan air volume), the natural cooling condition and the like. . The standby time setting unit 29 sets the hot water temperature in the heat exchanger increased by the post-boiling by the post-boiling amount calculated by the post-boiling amount calculation unit 26 and the heat radiation amount calculated by the heat radiation amount calculation unit 27. Within the range of the lower limit temperature of the temperature, the standby time for lowering to the preset lower limit operating temperature (the temperature corresponding to the lower limit operating temperature in the water heater having the bypass passage 11) is calculated and set, and the timer operation of the timer 31 is performed. To do.

On the other hand, the backup calorie calculator 28 sets the hot water temperature in the heat exchanger from the lower limit operating temperature (or the temperature corresponding to the lower limit operating temperature) based on the information such as the gas capacity, the water supply temperature and the water supply amount. A backup heat quantity required to raise to a predetermined heating upper limit temperature (a temperature corresponding to the heating upper limit temperature in the water heater having the bypass passage 11) preset within the upper limit allowable temperature range of the temperature is calculated. The combustion time calculation unit 30 calculates the combustion time of the hot water supply burner required to generate the backup heat quantity calculated by the backup heat quantity calculation unit 28.

When the standby time set by the standby time setting unit 29 elapses after the hot water supply burner is stopped, the combustion control unit 32 burns the hot water supply burner 3 for the time calculated by the combustion time calculation unit 30. Combustion is stopped by increasing the hot water temperature in the hot water supply heat exchanger that has decreased to the lower limit operating temperature (or the temperature corresponding to the lower limit operating temperature) to the heating upper limit temperature (or the temperature corresponding to the heating upper limit temperature).

Next, the specific operation of this embodiment will be described with reference to the flow chart shown in FIG. First, after combustion of the hot water supply burner 3 is stopped, it is judged from the detection signal of the flow sensor 7 whether or not the water flow rate has become zero, and after confirming that the water flow rate has become zero, the amount of post-boiling is 102 Calculate. In this case, the system of the water heater is as shown in FIG.
In the one provided with the bypass passage 11 as shown in,
The hot water supply temperature of the hot water supply heat exchanger 1 is higher than the hot water supply set temperature. For example, if the set temperature for hot water supply is 40 ° C,
When the upper limit allowable temperature is set to + 3 ° C. with respect to the set temperature and the lower limit allowable temperature is set to −3 ° C. with respect to the set temperature, the ratio of hot water coming out of the hot water supply heat exchanger and water coming out of the bypass passage 11 is 8: In the case of mixing with No. 2, when the water temperature is 15 ° C, in order for the hot water temperature after mixing to reach the set temperature of 40 ° C, the hot water supply heat exchanger creation temperature must be about 46.2 ° C. Then, in order to keep the hot water created by this hot water supply heat exchanger within 37 ° C of the lower limit allowable temperature after mixing, the temperature of the hot water in the hot water supply heat exchanger (the temperature corresponding to the lower limit allowable temperature) must be adjusted.
The temperature of the hot water in the hot water supply heat exchanger (the temperature corresponding to the upper limit allowable temperature) must be kept above 42.5 ° C, and in order to keep it within 43 ° C of the upper limit allowable temperature after mixing.
Must be within 50 ° C.

On the other hand, in the case of a water heater without the bypass passage 11, the set temperature of hot water and the temperature of hot water produced by the hot water heat exchanger are equal.

In the post-boiling amount calculation, the post-boiling amount after the combustion is stopped is calculated as the post-boiling heat amount or the post-boiling temperature based on conditions such as the gas capacity immediately before the combustion is stopped, the hot water supply set temperature, the water supply temperature, and the amount of hot water (water supply amount). Calculate with the value of.

Next, at step 103, the heat radiation amount after the combustion of the hot water supply burner 3 is stopped is calculated. In calculating the heat radiation amount, in the combined water heater, it is taken into consideration whether or not the bath burner 12 on the bath side is in the combustion operation. When another function operation such as bath reheating is being performed, when the common fan 22 is used for the bath burner and the hot water supply burner, the rotation of the fan 22 separates the hot water supply burner 3 and the bath burner 12 from each other. When the bath burner 12 is burning, the fan on the bath side rotates and the fan on the hot water supply burner side also rotates to prevent exhaust gas recirculation even when equipped with the fan Since it is performed, the air from the fan passes through the hot water supply heat exchanger 1 to produce a cooling action, and the hot air from the fan radiates heat. When the water heater has a single function, it is not necessary to consider the operation of other functions, and after the combustion of the hot water burner 3 is stopped, the hot water heat exchanger 1
Is cooled by natural cooling. When calculating the heat radiation amount, the above-mentioned cases are divided, and the heat radiation amount of the hot water supply heat exchanger 1 (heat radiation amount as a function of time) is calculated by using a given formula.

Next, at step 104, the amount of heat after boiling (or the temperature of hot water) is calculated from the calculation of the amount of heat radiation, and the bypass passage 11
In the case of having a hot water temperature assuming after mixing, in a water heater not having the bypass passage 11, the temperature of the hot water in the hot water heat exchanger is the lower limit operating temperature within the lower limit allowable temperature range, in this embodiment, for example, , When the tapping temperature is 40 ° C, the waiting time required for cooling to the lower limit operating temperature just before reaching the lower limit allowable temperature of 37 ° C is calculated and set. The relationship among the set temperature, the upper limit allowable temperature, the lower limit allowable temperature, the lower limit operating temperature, and the heating upper limit temperature is shown in FIG.

In step 105, the water having the lower limit operating temperature is heated to an upper limit temperature within the range of the upper limit allowable temperature of the set temperature. In this embodiment, for example, the set temperature of 40 ° C., the upper limit allowable temperature of 43 ° C.
The temperature just before is set as the heating upper limit temperature. From the lower limit operating temperature (the temperature corresponding to the lower limit operating temperature in the water heater having the bypass passage 11) to the heating upper limit temperature (bypass passage).
In a water heater having 11, a backup heat quantity required to raise the hot water temperature to a heating upper limit temperature) is calculated. Then, in step 106, the ignition heating time of the hot water supply burner required to generate this backup heat quantity is calculated.

In step 107, it is judged whether or not the fan rotation (or the fluctuation of the fan rotation) is caused by the operation of another function while the operations of the step 103 and the subsequent steps are performed, and the fan rotation (the fluctuation of the fan rotation) is generated. If so, the calculation result of the heat radiation amount and the calculation result of the standby time are distorted, so that the calculation operation after step 103 is redone. In step 108, it is determined whether or not the standby time set in step 104 has elapsed after the combustion was stopped. As shown in FIG. 4, when the waiting time has elapsed, the ignition operation is immediately performed, and the hot water supply burner is burned for the ignition heating time calculated in step 106. In step 110, when the ignition heating time has elapsed, it is determined that the backup heat quantity calculated in step 105 has been added to the hot water supply heat exchanger, and the fire is extinguished.
The operations after step 101 are repeated again.

According to this embodiment, every time combustion of the hot water heat exchanger 1 is stopped, the post-boiling amount calculation, the heat radiation amount calculation, the standby time calculation setting, the backup heat amount calculation, and the ignition are performed. The heating time is calculated and the hot water temperature that can be discharged (the assumed hot water temperature after mixing in a water heater with bypass passage 11 and the hot water temperature in the hot water heat exchanger in a water heater without bypass passage 11) is always the set temperature. Since the temperature is maintained within the upper and lower allowable temperature range for the hot water supply burner 3, even after the combustion of the hot water supply burner 3 is stopped, the faucet 25 is opened and the hot water is again discharged.
The hot water within the allowable temperature range relative to the set temperature can be discharged, the hot water temperature of the water heater can be stabilized, and the hot water can be used comfortably without any discomfort due to fluctuations in the hot water temperature. .

Further, according to this embodiment, even when the set temperature of the hot water supply is changed after the combustion of the hot water supply burner is stopped, the allowable temperature range corresponding to the changed set temperature and the allowable temperature range The lower limit operating temperature and the heating upper limit temperature are automatically changed to calculate the standby time, backup heat quantity, etc., so even if the set temperature is changed after combustion is stopped, it will be within the allowable temperature range of the changed set temperature. Stable hot water can be discharged.

The present invention is not limited to the above-mentioned embodiment, and various embodiments can be adopted. For example, in the above embodiment, the lower limit operating temperature was set at a temperature before the lower limit allowable temperature of the set temperature, but it may be set at the lower limit allowable temperature of the set temperature. Although the temperature is set to a temperature slightly lower than the upper limit allowable temperature of the set temperature, it may be set at the upper limit allowable temperature of the set temperature.

Although hot water and water are mixed using the bypass passage 11 in FIG. 3A, the present invention can be applied to a water heater using other mixing means.

Further, in the embodiment, the gas amount detection sensor 4
Although the information on the amount of heat held in the hot water supply heat exchanger is fetched by, the amount of heat held can be calculated from the conventional feedback feedforward control amount.

[0032]

According to the present invention, the standby time required for the hot water supply temperature to decrease to the lower limit operating temperature defined within the lower limit allowable temperature range of the set temperature is calculated and set every time the hot water heater stops combustion.
Every time this standby time elapses from the time when hot water supply combustion is stopped, the hot water temperature in the hot water heat exchanger is raised to the heating upper limit temperature set within the upper limit allowable temperature range of the set temperature or the temperature corresponding to this temperature, and the backup heat quantity is increased. Since it is configured to replenish by intermittent combustion, the hot water supply temperature will always be maintained within the allowable temperature range of the set temperature after the hot water heater has stopped combustion, and after a long time has elapsed after the hot water supply has stopped, Even when performing a hot water supply operation, stable hot water close to the set temperature can be discharged from the faucet.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment to which the method of the present invention is applied.

FIG. 2 is a flow chart showing the operation of the embodiment.

FIG. 3 is an explanatory diagram of various system examples of the water heater according to the present embodiment.

FIG. 4 is an explanatory diagram showing a mode of hot water temperature control according to the present embodiment.

FIG. 5 is an explanatory diagram showing hot water temperature fluctuation states in various cases of conventional hot water temperature control.

[Explanation of symbols]

 1 Hot water supply heat exchanger 3 Hot water supply burner 23 Control device 26 Post-boiling amount calculation unit 27 Heat dissipation amount calculation unit 28 Backup heat amount calculation unit 29 Standby time setting unit 30 Combustion time calculation unit 31 Timer 32 Combustion control unit

Claims (1)

[Claims] 1. The amount of after-boiling of the hot water in the heat exchanger is calculated by calculation from the hot water supply operating condition before the combustion is stopped each time when the combustion of the hot water supply is stopped, and then based on the heat radiation condition after the combustion is stopped. Corresponding to the lower limit operating temperature set within the lower limit allowable temperature range of the set temperature or the waiting time after combustion stop required to decrease to the temperature corresponding to this temperature and the lower limit operating temperature or this temperature From the temperature to the predetermined upper limit temperature of the set temperature, or the backup heat quantity necessary to raise the temperature of the hot water in the heat exchanger to the temperature corresponding to this temperature is calculated, A combustion control method for a water heater, which ignites every time the standby time elapses from the time of stop and performs intermittent combustion to supplement the backup heat quantity.