JPH07167494A - Control of water temperature of hot-water supplyer - Google Patents

Abstract

PURPOSE:To make a hot-water supplyer resume the supply of hot water always at a temperature pear a set point by a method wherein a quantity of backup heat required to raise the temperature of the hot water in the heat exchanger is calculated and the backup heat is supplied by the heating of a backup heater provided in the heat exchanger. CONSTITUTION:Through ST1 when the hot-water heater is supplying hot water at a set temperature, ST3 when the combustion is stopped, and ST4 where the amount of subsequent heating is calculated a control part decides at ST5 the lower limit of temperature for a hot-water supply temperature. Then a released heat-calculating part calculates at ST7 the quantity of heat escaping from the heat exchanger after stopping of the combustion and the quantity of heat to be supplied by a backup heater is determined. Next through ST11 where a heater control part applies power to the backup heater and ST16 where the heat exchanger is heated to the utmost and after an elapse of a required heating time the process advances to ST7 As a result, the hot-water heater when it resumes the supply is prevented from supplying hot water at a high temperature or at a low temperature due to cooling of the heat exchanger.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot water outlet temperature control method for a hot water heater for stabilizing the initial hot water temperature of a combustion hot water heater.

[0002]

2. Description of the Related Art In a combustion type water heater, when the combustion is stopped after its use, the hot water in the heat exchanger is gradually cooled. Therefore, when the hot water is discharged next time, the heat exchanger itself and the hot water in the heat exchanger are cooled, and when the hot water is discharged again, hot water at a temperature considerably lower than the set temperature of the water heater comes out.
It's inconvenient.

For this reason, in recent hot water heaters, the following method has been taken in order to stabilize the hot water discharge temperature. For example, according to the invention described in JP-A-5-10592, a hot water outlet flow rate controller is provided, and when the hot water outlet is stopped, the opening degree of the hot water outlet flow rate controller is controlled to be a predetermined opening degree in the throttle direction as compared with a steady state, and the The amount of rising water when tapping hot water is reduced.

As a result, a proposal has been made to make time for the hot water temperature to reach the set temperature to improve the re-hot water discharge characteristic. As a result,
The hot water is discharged at a temperature as close as possible to the set temperature.

[0005]

However, such a method has the following drawbacks. First, even if the faucet is opened, only a small amount of hot water comes out, so it is determined that the opening of the faucet is not appropriate, and the opening of the faucet of the faucet is further increased. Then, a large amount of hot water suddenly comes out of the faucet, and there is a problem that the user feels extremely uncomfortable.

The present invention has been made to solve the above problems, and when hot water is again discharged after combustion of the water heater is stopped, hot water can be stably discharged at a temperature as close as possible to a set temperature. An object of the present invention is to provide a combustion control method for a reactor.

[0007]

According to the present invention, the object of the present invention is to obtain the amount of after-boiling of hot water in the heat exchanger from the hot water supply operating conditions before the combustion is stopped every time the hot water supply is stopped. Based on the heat dissipation condition after combustion stop, the cooling time for the hot water temperature after post-boiling to fall to the lower limit temperature set within the lower limit allowable temperature range for the set temperature or the corresponding temperature, and the above lower limit temperature or the corresponding Temperature of the backup heat required to raise the temperature of the hot water in the heat exchanger to the upper limit temperature set within the upper limit allowable temperature or the temperature corresponding to it, and the heating of the backup heater installed in the equipment is calculated. Is achieved by the combustion control method of the water heater, which supplements the above-mentioned backup heat quantity.

[0008] Preferably, when the hot water temperature after the after-boiling exceeds the upper limit allowable temperature range, a fan installed in the equipment is driven to control the hot water temperature in the heat exchanger to be lowered.

Further, preferably, the heating of the backup heater is started before the elapse of the cooling time.

[0010]

According to the above method, after the combustion of the water heater is stopped, the amount of after-boiling in the heat exchanger of the water heater is calculated, and the time for the hot water temperature after the after-boiling to fall near the set temperature is calculated. Or if the elapsed time after the combustion has stopped is long,
The backup heat quantity for heating the lowered temperature to near the set temperature is calculated. By operating the backup heater based on this calculation result,
At the time of re-pouring hot water, the hot water at a temperature near the set temperature is always poured out.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings. The examples described below are
Since it is a preferred specific example of the present invention, various technically preferable limitations are attached, but the scope of the present invention is, unless otherwise stated to limit the present invention, in the following description.
It is not limited to these modes.

1 and 2 show an example of a combustion type water heater system to which the method of this embodiment is applied. FIG. 1 shows a single-function water heater, and FIG. 2 shows an example of a combined water heater. Shows.
The water heater 30 of FIG. 1 has a water supply pipe 5 connected to the inlet side. A flow sensor 7 is connected to the water supply pipe 5 so that the amount of water entering can be detected. Further, a water supply temperature sensor 6 is connected to the water supply pipe 5, and is also connected to the heat exchanger 1. Further, preferably, the water supply pipe 5 is branched and connected to a bypass pipe 11 that does not pass through the heat exchanger 1, and the bypass pipe 11 is connected to a hot water outlet pipe 8 described later.

The outlet of the heat exchanger 1 is connected to a hot water outlet pipe 8, which is provided with a hot water outlet temperature thermistor 10 and a hot water tap 25. A burner 3 for heating the heat exchanger 1 is provided in the water heater 30.
A gas valve 2 for sending fuel gas is connected to the burner 3, and a gas amount detection sensor 4 is connected to the gas pipe in order to detect the gas supply amount from the gas valve 2.

A backup heater 13 is provided near the heat exchanger 1. The backup heater 13 is connected to a control unit as described later, and is composed of a ceramic heater, a sheath heater, an electromagnetic heating heater, or the like so that heating control can be performed after combustion of the burner 3 is stopped. ing. Here, the backup heater 13 may be arranged not only adjacent to the heat exchanger 1 but also directly in the water pipe. In addition, the heater 13
A heat pipe or the like may be arranged between the heat exchanger 1 and the heat exchanger 1, or between the heater 13 and the water pipe.

Further, a fan 22 is built in the water heater 30 to supply combustion air to the combustion chamber. Further, a rotation detection sensor 9 for detecting the rotation speed of the fan 22 is provided, and an outside air temperature detection means 19 for detecting the intake air temperature sucked by the fan 22 is provided.

Further, the water heater 30 includes a flow sensor 7, a water supply thermistor 6, a heater 13, an outlet hot water thermistor 10, a gas valve 2, a gas amount detection sensor 4, and a fan 22.
Also, it has a control unit 23 to which the fan rotation detection sensor 9 and the outside air temperature detection sensor (outside air temperature thermistor) 19 are connected. The control unit 23 operates the water heater 30 under the conditions set by the remote controller 24 by receiving a predetermined signal from each of these connection points or issuing a command. The remote controller 24 is provided with a button 24a for the user to set a set temperature as a hot water outlet temperature, a set temperature display section 24b, and the like.

The combined water heater 35 of FIG. 2 is obtained by adding a reheating function to the single-function water heater 30 of FIG. 1, and has the (hot water) heat exchanger 1 and the bath heat exchanger 2 side by side. That is,
A bath burner 12 is set in the bath heat exchanger 2, and the bath heat exchanger 2 is heated by the bath burner 12.

The return pipe 16 of the circulation pipe 15 is connected to the inlet of the bath heat exchanger 2. The return pipe 16 has a hot water outlet pipe 8
The branch pipe 20 from is connected. The reheating circulation pump 14 is connected to the return pipe 16, and the outlet side of the bath heat exchanger 2 and the bath 17 are connected by a forward pipe 18. Further, in the case of the water heater 35, the bath side fan 27 for supplying combustion air to the bath side combustion chamber, the fan rotation detection sensor 28a and the outside air temperature detection sensor 18 are provided.
b is set.

In the composite water heater 35, the fans 22 and 27 are individually set for hot water supply and bath use, but they may be combined into one fan. Further, the hot-water supply side exhaust A1 and the bath-side exhaust A2 join together in one exhaust passage 36.

These water heaters 30 and 35 are provided with faucets 25.
The flow sensor 7 detects the flow of water entering the heat exchanger 1 (hot water supply) by opening. In response to the signal from the flow sensor 7, the controller 23 supplies gas and ignites an igniter electrode (not shown).

As a result, the burner 3 (for hot water supply) is burned to heat the heat exchanger 1, and the water passing through the heat exchanger 1 is turned into hot water and discharged from the hot water discharge pipe 8 through the hot water tap 25. . Then, when the faucet 25 is closed and the OFF signal from the flow sensor 7 is no longer detected, the control unit 23 stops the combustion of the burner 3.

When the hot water in the bathtub 17 is reheated in the water heater 35, the valve 21 is closed, the reheating circulation pump 14 is operated, and the bath burner 12 is ignited. The heat exchanger 2 for bath is heated by burning. As a result, the hot water in the bathtub 17 is heat-exchanged by passing through the heat exchanger 2 while circulating in the circulation pipe line 15 for additional heating.

Here, when the combustion of the water heater 30 and the burner 3 is stopped, that is, when the combustion of the water heater 30 is stopped, the heat in the water pipe surrounded by the heat exchanger 1 is heated by the heat exchanger 1. The heat possessed by is transferred and becomes hot water. This phenomenon is called "after boiling". Next, the fan 22 is rotated, and after combustion is stopped, the combustion exhaust gas remaining in the device is discharged from the exhaust passage 36 for safety (post fan).
Then, the heat exchanger 1 is cooled by the wind caused by the introduction of the outside air. Therefore, the heat quantity of the hot water in the heat exchanger 1 is deprived to the heat exchanger 1 side, and the temperature of the hot water gradually decreases.

In this case, the method of this embodiment prevents low-temperature hot water from coming out of the hot water supply pipe 8 when the hot water heaters 30 and 35 are re-combusted.
It is intended to stably supply hot water having a temperature not much different from the temperature set by the remote controller 24.

The same problem also occurs when the composite water heater 35 is reheated. That is, in this case, due to the rotation of the fan 27, the combustion exhaust A3 from the bath burner 2 is guided from the common exhaust passage 36 to the hot water supply side combustion chamber and circulates. This is because in order to prevent this, the fan 22 must be rotated even when hot water supply combustion is not performed, which cools the hot water supply heat exchanger 1.

Therefore, the method of this embodiment is also applied to the case of heat radiation of the heat exchanger 1 for hot water supply, which occurs when the combined water heater 35 is reheated. Even when the combined water heater 35 has only one fan, the wind of the fan that is rotated during the reheating operation is sent not only to the bath side but also to the hot water supply heat exchanger 1, so that heat exchange is also required. A similar problem occurs when the container 1 is cooled. Also in this case, the method according to the present embodiment is effective.

FIG. 3 is a block diagram showing a main portion of the control unit 23, which is particularly closely related to the combustion method of this embodiment. The combustion control unit 40 includes a post-boiling amount calculation unit 41, a heat radiation amount calculation unit 42, a backup heat amount calculation unit 43, an energization start time setting unit 44 for the backup heater 13, and a heater control unit 45. There is.

The post-boiling amount calculation unit 41 is based on the combustion state immediately before the combustion of the water heater 30 is stopped, that is, the conditions such as the gas combustion capacity, the hot water supply flow rate, the water supply temperature, and the set temperature set by the remote controller 23. , The amount of post-boiling in the heat exchanger 1 is calculated. This calculation is performed based on the amount of heat or the value of the post-boiling temperature in the heat exchanger 1. For this calculation, a calculation formula in which a theoretical formula is corrected by experiments is used.

The heat radiation amount calculation unit 42 uses a calculation formula given in advance for the heat radiation amount of the heat exchanger 1 based on the intake temperature of the fan 22, the capacity of the fan (fan air volume), the natural cooling condition, and the like. Calculated as a function of time. Alternatively, a thermistor or the like may be set in the heat exchanger 1, the temperature in the heat exchanger 1 may be directly detected, and an arithmetic expression corrected by an experiment may be used. The post-boiling amount calculation unit 41 and the heat radiation amount calculation unit 42 are connected to the energization start time setting unit 44, respectively.

The energization start time setting unit 44 receives the calculation result of the post-boiling amount calculation unit 41 and the calculation result of the heat radiation amount calculation unit 42, and after the combustion of the water heater 30 is stopped, the heat increased by the post-boiling. Time for the temperature of the hot water in the exchanger 1 to fall to a preset lower limit temperature (the temperature corresponding to the lower limit temperature when the bypass pipe 11 is provided) within the lower limit allowable temperature range of the hot water supply set temperature, that is, "cooling""Time" is calculated, and the energization start time for the backup heater 13 is set based on this.

The backup calorie calculation unit 43 is provided in the control unit 2.
3, the hot water temperature in the heat exchanger 1 based on the information such as the gas capacity, the feed water temperature, and the feed water amount stored in the memory unit (not shown) is set to the lower limit temperature within the above lower limit allowable temperature range, or Calculate the amount of backup heat required to increase from the temperature corresponding to the lower limit temperature to the preset upper limit temperature (the temperature corresponding to the upper limit temperature when the bypass pipe 11 is provided) within the upper limit allowable temperature range of the hot water supply set temperature Ask by.

The heater control section 45 is connected to the energization start time setting section 44 and the backup calorie calculation section 43, respectively. As a result, the energization timing of the backup heater 13 and the supply current amount are determined based on the calculation result of the energization start time calculation unit 44 and the calculation result of the backup heat amount calculation unit 43. To heat. Thereby, the hot water in the heat exchanger 1 is set from the temperature corresponding to the lower limit temperature or the lower limit temperature preset in the lower limit allowable temperature range to the upper limit temperature (preset in the upper limit allowable temperature range of the hot water supply set temperature). When the bypass pipe 11 is provided, heating is performed until the temperature rises to the upper limit temperature).

Next, the combustion method of this embodiment will be described in detail with reference to the flowchart of FIG. When the water heater 30 is performing an automatic operation of discharging hot water at the set temperature (S
At T1), when the flow sensor 7 receives a signal of water flow rate 0 from the control unit 23 (ST2), the control unit 23 determines that the combustion is stopped (ST3), and the post-boiling amount calculation unit 41 calculates the post-boiling amount. Is calculated (ST4).

As described above, the post-boiling amount calculation unit 41 determines the combustion state of the water heater 30 immediately before the combustion is stopped, that is, the gas combustion capacity, the hot water supply flow rate, the water supply temperature, the set temperature set by the remote controller 23, and the like. The amount of post-boiling in the heat exchanger 1 is calculated based on the conditions. Next, in ST5, the control unit 23 determines whether or not the temperature due to this post-boiling is lower than the lower limit temperature of the set temperature, for example, 37 ° C., which is 3 ° lower than the lower limit temperature of 40 ° C. .

If a negative result is obtained in ST5, the process proceeds to ST14 described later, and if a positive result is obtained, the process proceeds to ST6. In this step (ST6), the control unit 23 determines whether the temperature due to the post-boiling is higher than the upper limit temperature with respect to the set temperature, for example, when the set temperature is 40 degrees C, it is higher than 43 degrees C which is 3 degrees higher than this. To do. Here, if a positive result is obtained, the operation proceeds to ST17, which will be described later, and if a negative result is obtained, the operation proceeds to ST7. After the combustion is stopped, post-boiling occurs as described above, so the routine normally proceeds to ST17, and after cooling by the fan is completed, proceeds to ST7.

Next, the heat radiation amount calculation unit 42 calculates the heat radiation amount of the heat exchanger 1 after the combustion is stopped (ST7). That is,
The outside temperature thermistor 19 detects the temperature of the outside air taken into the device by the fan 22, and based on this, the intake temperature of the fan 22, the capacity of the fan (fan air volume), the natural cooling conditions, etc., of the heat exchanger 1. The amount of heat radiation is obtained as a function of time using an arithmetic expression given in advance (ST7).

Next, the transmission start time setting unit 44 calculates the time to start energizing the backup heater 13 (ST8). That is, the energization start time setting unit 44 receives the calculation result of the post-boiling amount calculation unit 41 and the calculation result of the heat radiation amount calculation unit 42, and after the combustion of the water heater 30 is stopped, the heat exchanger that has risen due to post-boiling. The time until the temperature of the hot water in 1 is cooled by the rotation of the fan 22 after the combustion is stopped and heating is required is calculated.

Next, the heat quantity to be supplemented by the backup heater 13 is calculated by the backup heat quantity calculation section 43. Here, the backup calorie calculation unit 43
Calculates the amount of heat for raising the hot water temperature (lower limit temperature) in the heat exchanger 1 after the combustion is stopped to the set temperature set by the remote controller 24.

Specifically, from a lower limit temperature preset in the lower limit allowable temperature range or a temperature corresponding to the lower limit temperature, an upper limit temperature preset in the upper limit allowable temperature range of the hot water supply set temperature (bypass pipe 11 If it has, the backup heat amount required to raise the temperature to the upper limit temperature) is calculated based on information such as the gas capacity supplied to the water heater 30, the water supply temperature, and the water supply amount.

Here, for example, when the temperature set by the remote controller 23 is 40 ° C. and the water temperature is 15 ° C., the upper limit temperature and the lower limit temperature are plus or minus 3 ° C.
When the bypass ratio is 8 (heat exchanger 1 side) to 2 (bypass side), the temperature corresponding to the upper limit temperature in the heat exchanger 1 is 50.
C, the set temperature is 46.2 C, and the temperature corresponding to the lower limit temperature is 42.5 C. On the other hand, when the bypass pipe 11 is not provided, these temperatures are 43 degrees C (upper limit temperature), 40 degrees C (set temperature), and 37 degrees C (lower limit temperature).

Next, after waiting for a time shorter than the energization start time set in ST8 by x hours (x minutes) from the combustion stop (ST10), the heater control section 45 energizes the backup heater 13. The heat exchanger 1 is heated (ST11). Here, as shown by the chain double-dashed line in FIG. 5, when heating by the heater 13 is not performed and the time set in ST8 as the energization start time elapses, the hot water temperature of the heat exchanger 1 is set to the set temperature. When the heater is heated after that, the hot water temperature does not rise during the time when the heat exchanger 1 warms up.

Therefore, the time for remaining heat of the heat exchanger 1 is expected to be x hours (x minutes), and the heater heating is performed earlier by subtracting that amount from the energization start time. This allows the hot water temperature in the heat exchanger 1 to quickly follow the set temperature. In addition, this x time (x minutes) is
For example, it is obtained in advance by experiments for each type of heat exchanger incorporated in the target water heater and stored in a memory (not shown) of the control unit 23.

At the time of hot water re-spouting, it is confirmed with the control unit 23 whether or not the temperature setting is changed by the remote controller 24 (ST12). When a positive result is obtained, the process proceeds to ST13, and it is confirmed whether or not the change of the set temperature is within the upper limit or the lower limit of the allowable temperature range. If so, return to ST7. Here, when the newly set temperature is higher than the upper limit allowable temperature range, the process proceeds to ST14, where the backup calorie calculation unit 43 is required to heat the hot water temperature in the heat exchanger 1 to the new set temperature. Calculate the amount of heat.

Based on the calculation result, the heater controller 4
5 sends an instruction to the backup heater 13, and the backup heater 13 heats the heat exchanger 1 to the maximum (ST1
6). Then, when the required heating time elapses (ST1
6) Go to ST7.

In ST13, if the newly set temperature is lower than the lower limit allowable temperature, the process proceeds to ST17 and the fan 2
The time to be cooled by 2 is calculated by the heat radiation amount calculation unit 42. Upon receiving the calculation result, the control unit 23 rotates the fan 22 (ST18), and when the time based on the calculation result has elapsed (ST19), stops the fan 22 (ST20) and returns to ST7.

If the set temperature is not changed by the remote controller 24 in ST12, the process proceeds to ST21. here,
The control unit 23 rotates the fan 22 for a predetermined time and rotation speed, and discharges combustion exhaust gas by rotating the post fan after the combustion is stopped. Next, in the case of a compound water heater like the water heater 35, it is confirmed whether the fan 27 is rotated by additional heating (ST22), and if a positive result is obtained, the process returns to ST21. If a negative result is obtained here, the process returns to ST7. It should be noted that the combustion control according to the flowchart of FIG. 4 is designed to be operated for several minutes after the automatic combustion operation is performed by the water heater, and is ended when the time elapses.

As described above, according to the combustion control method of the present embodiment, after the combustion of the water heater is stopped, the amount of after-boiling in the heat exchanger of the water heater is calculated, and the temperature of the water after the after-boiling is determined. However, the time to fall to the vicinity of the set temperature is calculated, or if the elapsed time after the combustion has stopped is long, the backup heat quantity for heating the lowered temperature to the vicinity of the set temperature is calculated. By operating the backup heater based on the calculation result, the heat exchanger is heated, and when the hot water is again discharged, hot water having a temperature near the set temperature is constantly discharged.

For this reason, it is possible to avoid the danger that hot water will come out when hot water is again discharged as in the conventional case. Furthermore, after the combustion is stopped, the heat exchanger is cooled and the temperature of the hot water in this heat exchanger is not taken away, so it is possible to effectively prevent unpleasant feelings from coming out of low temperature water when re-leaving hot water. it can.

[0049]

As described above, according to the present invention, when hot water is discharged again after the hot water heater has stopped burning, it is possible to stably discharge hot water at a temperature as close as possible to the set temperature. A combustion control method can be provided.

[Brief description of drawings]

FIG. 1 is a system diagram showing a configuration example of a single-function water heater to which a combustion control method according to a preferred embodiment of the present invention is applied.

FIG. 2 is a system diagram showing a configuration example of a combined water heater to which a combustion control method according to a preferred embodiment of the present invention is applied.

FIG. 3 is a block configuration diagram showing a main part of a control unit that performs combustion control according to the present embodiment.

FIG. 4 is a flowchart showing an example of a combustion control method according to this embodiment.

FIG. 5 is a diagram showing changes in hot water temperature in the heat exchanger in the combustion control method of the present embodiment in comparison with the case of conventional combustion control.

[Explanation of symbols]

 1 (for hot water supply) heat exchanger 3 (for hot water supply) burner 4 gas amount detection sensor 5 water supply pipe 6 water entry thermistor 7 flow sensor 8 hot water discharge pipe 10 hot water discharge thermistor 11 bypass pipe 12 (for bath) burner 13 return pipe 14 reheating circulation Pump 15 Circulation pipeline 17 Bathtub 18 Outgoing pipe 19 Outside air temperature thermistor 22 Fan 23 Control unit 24 Remote control 27 Fan 30 Single-function water heater 35 Combined water heater 41 Post-boiler amount calculation unit 42 Heat dissipation amount calculation unit 43 Backup heat amount calculation unit 44 Energization Start time setting unit 45 Heater control unit

Claims (3)

[Claims] 1. The amount of post-boiling of hot water in the heat exchanger is calculated every time combustion of the water heater is stopped, and the hot water temperature after post-boiling is the lower limit allowable temperature range with respect to the set temperature based on the heat radiation condition after the combustion is stopped. The cooling time to fall to the lower limit temperature or the temperature corresponding to it, and the lower limit temperature or the temperature corresponding to it to the upper limit temperature defined within the upper limit allowable range or the temperature corresponding to it It is characterized in that the backup heat quantity required to raise the hot water temperature is calculated, and the backup heat quantity is supplemented by heating a backup heater provided in the equipment.
Method of controlling hot water temperature of water heater. 2. When the hot water temperature after the after-boiling exceeds the upper limit allowable temperature range, a fan provided in the equipment is driven to lower the hot water temperature in the heat exchanger.
The method for controlling the outlet temperature of a water heater according to. 3. The hot water outlet temperature control method for a water heater according to claim 1, wherein heating of the backup heater is started before the elapse of the cooling time.