JP2531337B2 - How to operate the 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 method of operating a water heater.

[0002]

2. Description of the Related Art Conventionally, a burner having a constant burning capacity is used.
When a predetermined set hot water temperature is instantaneously tapped by cycle combustion consisting of a combination of combustion on time and combustion off time, and when a calorific value less than a predetermined minimum cycle combustion calorific value is required corresponding to the set hot water temperature. There is provided a water heater in which the hot water outlet temperature is higher than the set temperature, but combustion is performed by cycle combustion with the minimum cycle combustion heat amount. In the water heater, particularly when a heat quantity less than the minimum cycle combustion heat quantity is required corresponding to the set hot water temperature, the hot water temperature is higher than the set hot water temperature because it burns at the lowest cycle combustion heat quantity. Of course, since there is a possibility that the hot water will boil, the hot water temperature is calculated from the hot water temperature, the hot water flow rate, and the minimum cycle combustion heat quantity during operation, and the hot water boiling temperature is constant. When the temperature exceeds the dangerous temperature, the cycle combustion is stopped, and when the calculated hot water discharge temperature is below a certain restart temperature, the cycle combustion is restarted.

[0003]

However, in the above-described conventional method of operating a water heater, when the flow rate of water entering the water heater varies greatly and frequently, the calculated hot water outlet temperature frequently boils due to this flow rate change. As a result, the temperature above the dangerous temperature and the temperature below the resumption temperature are repeated, and as a result, the cycle combustion operation is frequently turned on and off at the minimum cycle combustion heat quantity, and there is a problem that the hot water comes to a boiling state.

Therefore, the present invention solves the above-mentioned drawbacks of the prior art, and when a calorific value less than the minimum cycle combustion calorific value is required corresponding to the set tap water temperature, the change in the incoming water flow rate is large and frequently changes. Even in such cases, it is an object of the present invention to provide a method of operating a water heater that can prevent the boiling water temperature from boiling.

[0005]

In order to achieve the above object, the method of operating a water heater according to the present invention uses a burner having a constant combustion capacity and a predetermined cycle combustion cycle consisting of a combination of combustion ON time and combustion OFF time. When the preset hot water discharge temperature is instantaneously discharged, and when a heat quantity less than a predetermined minimum cycle combustion heat quantity is required corresponding to the preset hot water discharge temperature, combustion is performed by cycle combustion at the minimum cycle combustion heat quantity. During operation, the hot water temperature calculated from the incoming water temperature, the incoming water flow rate, and the minimum cycle combustion heat quantity is monitored, and when the calculated hot water temperature exceeds a certain boiling critical temperature, cycle combustion is stopped, and the calculated hot water temperature is constant. A method of operating a water heater which restarts cyclic combustion when the temperature is below the restart temperature, wherein the calculated hot water discharge temperature is above a certain boiling danger temperature. At the same time so as to start a off timer for a predetermined time and cycle combustion stop by,
Until the timer time by the off timer elapses, at least the cycle combustion is not restarted even if the calculated hot water discharge temperature becomes equal to or lower than the restart temperature.

[0006]

According to the features of the present invention, when the hot water supply operation switch is turned on and the cullan is opened and the flow rate becomes equal to or higher than the minimum operation start flow rate, the burner combustion is started. Then, the required heat quantity of the burner is calculated from the set hot water temperature, the incoming water temperature, and the incoming water flow rate, and a cycle consisting of the combustion on time and the combustion off time to reach the calculated required heat quantity is calculated, and this operation is performed. By repeating combustion ON and combustion OFF in this cycle, the normal hot water discharge is performed at the set hot water temperature. Next, if the required combustion heat quantity of the burner obtained from the incoming water temperature and the incoming water flow rate is less than the predetermined minimum cycle combustion heat quantity with respect to the set outlet temperature, cycle combustion at the minimum cycle combustion heat quantity is performed. Done. During operation, the hot water temperature calculated from the incoming water temperature, the incoming water flow rate, and the minimum cycle combustion heat quantity is monitored, and if the calculated hot water temperature exceeds a certain boiling critical temperature, cycle combustion is stopped. At the same time, an off-timer for a fixed time is started, and after the timer time by this off-timer elapses, the cycle combustion is restarted when the calculated hot water discharge temperature becomes equal to or lower than the restart temperature. As described above, according to the present invention, when the calculated hot water temperature once becomes equal to or higher than the boiling danger temperature, the off timer is used to stop the combustion for a certain period of time. Even when the calculated hot water temperature is frequently repeated above the boiling critical temperature and below the resuming temperature, it is possible to reliably prevent the hot water temperature from gradually increasing and reaching boiling.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic configuration diagram of a water heater for explaining the method of the present invention, FIG. 2 is a diagram showing an example of the relationship between the incoming water temperature, the incoming water flow rate, and the calculated outgoing hot water temperature. FIG. It is a flow chart which shows an example.

In FIG. 1, the water that has entered the instantaneous heat exchanger 2 through the water inlet pipe 1 is heated there and is discharged to the hot water outlet pipe 3. Reference numeral 4 is a burner having a constant burning capacity. Further, 5 is a water amount sensor, 6 is a water temperature sensor, and 7 is a controller for controlling the entire apparatus. The burner is, for example, an oil burning burner and has a certain burning capacity,
Combustion operation is started when the water amount sensor 5 detects the minimum working water amount by opening a not-shown currant.
In the combustion operation, first, the combustion chamber of the burner 4 is pre-purged,
After the igniter is preliminarily operated, ignition is performed to start combustion. The operation control method by the controller 7,
Further description will be given with reference to FIGS.

Now, when the hot water supply switch is turned on, the unillustrated currant is opened, and when the water amount sensor 5 detects a water amount equal to or higher than the minimum working water amount (S1), the controller 7 performs the combustion including the pre-purge and the preliminary ignition operation. Preliminary operation is started (S2), and at the same time, the required combustion heat quantity Q _E is calculated from the incoming water temperature by the incoming water temperature sensor 6, the incoming water flow rate by the water quantity sensor 5, and the set hot water temperature (S3). It is determined whether or not Q _E is _{equal to} or more than a predetermined minimum cycle combustion heat quantity Q _MIN in the burner 4 having the constant combustion capacity (S4). The minimum cycle combustion heat quantity Q
_MIN is the combustion heat quantity in the cycle combustion with the worst conditions when the burner 4 having a constant combustion capacity is subjected to on / off cycle combustion consisting of a combination of combustion on time and combustion off time. , Is determined in advance by experiments or the like from the combustion heat quantity of the burner 4 in continuous operation. If the required combustion heat quantity is equal to or greater than the minimum cycle combustion heat quantity Q _MIN in step S4 (Yes in S4), the calculated necessary combustion heat quantity Q _E and the constant combustion capacity of the burner 4 (requiring the required combustion heat quantity Have the ability to cross)
From the above, the combustion ON time and the combustion OFF time for obtaining the required combustion heat quantity Q _E are calculated, and the ON / OFF cycle combustion is performed by the combination of the calculated combustion ON time and combustion OFF time (S5).

On the other hand, in step S4, the required combustion heat quantity Q
_{When E} is less than the minimum cycle combustion heat quantity Q _MIN (S4
No, the hot water temperature will be higher than the set temperature,
Cycle combustion is performed with the minimum cycle combustion heat quantity Q _MIN (S6). And in the cycle combustion in the minimum cycle combustion heat Q _MIN, always, the incoming water temperature T _N and the incoming water flow rate F and the minimum cycle heat of combustion operation is calculated from the Q _MIN tapping temperature _{T C (T C = Q MIN} / F + T _N ) is monitored, and when the calculated hot water discharge temperature T _C is equal to or higher than the boiling dangerous temperature T _B (Yes in S7), the cycle combustion is stopped and the off timer is started (S8). _As shown in FIG. 2, _C is, for example, the minimum cycle combustion heat quantity Q _MIN is 75 kcal / hour, and the incoming water temperature T _N
Is 60 ° C. and 50 ° C., the boiling dangerous temperature T _B and the restarting temperature T _R fluctuate as the water flow rate F fluctuates. That is, when the incoming water flow rate F frequently fluctuates greatly, the calculated hot water discharge temperature T _C frequently fluctuates beyond the boiling critical temperature T _B and the restart temperature T _R. Therefore, simply calculating the hot water temperature T when _C is equal to or higher than the boiling critical temperature T _B to stop the operation of the cycle combustion, the control of combustion to initiate the operation of the cycle combustion becomes below resumes the temperature T _R, a frequent combustion Because of the start, the actual tap water temperature reaches the boiling range.

In the case of the present invention, during the cycle combustion with the minimum cycle combustion heat quantity Q _MIN , when the calculated hot water discharge temperature T _C becomes higher than the boiling dangerous temperature T _B , the cycle combustion is stopped and the controller 7 is turned off. The timer is started (S8), and until the constant timer time by this off timer elapses (No in S9), even if the calculated tap water temperature T _C becomes equal to or lower than the restart temperature T _R , cycle combustion I try not to restart the operation of. Then, in step S9, after the timer time has elapsed (YES in S9), if the calculated hot water discharge temperature T _C becomes equal to or lower than the restart temperature T _R (YES in S10), the cycle combustion is restarted from the preliminary operation. (S2).

[0012]

According to the method of operating a water heater according to the first aspect of the present invention, when the required combustion heat quantity of the burner is less than the minimum cycle combustion heat quantity, the minimum cycle heat quantity is obtained. If the calculated hot water temperature exceeds a certain boiling critical temperature during the operation, the off timer for a certain time is started simultaneously with the stop of the cycle combustion. Until the time elapses, at least the cycled combustion is not restarted even if the calculated hot water temperature becomes the restart temperature or lower, so the calculated hot water temperature is above the boiling danger temperature and below the restart temperature due to frequent fluctuations in the incoming water flow rate. Even when the above and the above are frequently repeated, it is possible to reliably prevent the tapping temperature from gradually rising and boiling.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a water heater for explaining the method of the present invention.

FIG. 2 is a diagram showing an example of a relationship among a water inlet temperature, a water inlet flow rate, and a calculated hot water outlet temperature.

FIG. 3 is a flowchart showing an embodiment of the method of the present invention.

[Explanation of symbols]

 1 Inlet pipe 2 Instantaneous heat exchanger 3 Outlet pipe 4 Burner 5 Water amount sensor 6 Inlet temperature sensor 7 Controller

Claims (1)

(57) [Claims] 1. A burner having a constant combustion capacity is used to instantaneously discharge a predetermined set hot water temperature by cycle combustion consisting of a combination of a combustion on time and a combustion off time, and a calorific value less than a predetermined minimum cycle combustion calorific value. Is required corresponding to the set hot water temperature, the hot water temperature is calculated from the incoming water temperature, the incoming water flow rate, and the minimum cycle combustion heat quantity during operation while performing combustion in cycle combustion at the minimum cycle combustion heat quantity. It is a method of operating a water heater in which the cycle combustion is stopped when the calculated hot water temperature exceeds a certain boiling critical temperature, and the cycle combustion is restarted when the calculated hot water temperature falls below a certain restart temperature. , When the calculated hot water discharge temperature exceeds a certain boiling danger temperature, the off timer for a certain time is started at the same time as the cycle combustion is stopped. Thus, the method of operating the water heater is characterized in that the cycle combustion is not restarted at least until the calculated hot water discharge temperature becomes equal to or lower than the restart temperature until the timer time by the off timer elapses.