JPH0566056A - Controller for hot water supplying apparatus - Google Patents

Abstract

PURPOSE:To suppress the drop of an output hot water temperature when hot water outputting is intermittently conducted and a burner is repeatedly operated and stopped in a controller for a hot water supplying apparatus in which the burner is operated and stopped in response to a water temperature and a set temperature of a heat exchanger. CONSTITUTION:A microcomputer 16 operates a burner 7 at an interval in the order of a burner fan 20, an igniter 21 and a fuel supply pump 22 when the detected temperature of a temperature detector 12 is lower than a set temperature. The operating interval (prepurging time) of the fan 20 and the pump 22 is varied in response to the detected temperature of the detector 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control of a water heater including a burner, a heat exchanger for exchanging heat between combustion gas of the burner and water, and a water supply pipe and a hot water discharge pipe connected to the heat exchanger. Regarding the device.

[0002]

2. Description of the Related Art In this type of water heater, for example
As disclosed in Japanese Patent Publication No. 25621, a temperature detector for detecting a water temperature of a heat exchanger, and a burner for starting and stopping a burner according to a set temperature determined by the temperature detector and a detected temperature of the temperature detector. And a control device having control means. Then, when the detected temperature of the temperature detector becomes lower than the ON set temperature, the burner is operated at intervals in the order of the burner fan, the ignition device and the fuel supply means, and when the detected temperature becomes higher than the OFF set temperature, the burner is stopped. I am trying.

[0003]

In the above-described hot water heater control device, when the burner control means operates the burner, the burner fan, the ignition device, and the fuel supply means are sequentially operated at intervals so that the burner fan and the fuel are operated. Since the operation interval (prepurge time) with the supply means is sufficient,
Hot water is intermittently discharged from the heat exchanger to the utilization section, and if the burner is repeatedly started and stopped, the hot water temperature of the heat exchanger with a small capacity will drop significantly, or the water will be discharged as is. There was such a problem.

The present invention has been made in view of the above-mentioned fact, and an object of the present invention is to suppress the drop in hot water temperature when hot water is intermittently discharged and the burner is repeatedly started and stopped.

[0005]

According to the present invention, there is provided a hot water supply including a burner, a heat exchanger for exchanging heat between combustion gas of the burner and water, and a water supply pipe and a hot water supply pipe connected to the heat exchanger. In the machine, a temperature detector for detecting the water temperature of the heat exchanger, a temperature setter, and burner control means for starting and stopping the burner according to the set temperature determined by the temperature setter and the detected temperature of the temperature detector, The burner control means operates the burner at intervals in the order of the burner fan, the ignition device and the fuel supply means when the temperature detected by the temperature detector is lower than the set temperature, and the burner fan and the fuel supply means are provided. The operation interval (pre-purge time) between and is changed according to the temperature detected by the temperature detector.

Further, according to the present invention, in a water heater provided with a burner, a heat exchanger for exchanging heat between combustion gas of the burner and water, and a water supply pipe and a hot water supply pipe connected to the heat exchanger, A temperature detector for detecting the water temperature of the exchanger, a temperature setter, and a burner control means for starting and stopping the burner according to the set temperature determined by the temperature setter and the detected temperature of the temperature detector, The burner control means operates the burner at intervals of the burner fan, the ignition device and the fuel supply means in this order when the temperature detected by the temperature detector is lower than the set temperature, and the operation interval between the igniter and the fuel supply means. (Pre-ignition time) is configured to be changed according to the temperature detected by the temperature detector.

[0007]

With this structure, the pre-purge time can be shortened when the temperature detected by the temperature detector for detecting the water temperature of the heat exchanger is high, and the drop in tapping temperature when tapping is performed intermittently becomes small. When the temperature detected by the temperature detector is high, the burner has once been operated and sufficient pre-purge has been performed, and the fuel in the burner is easily discharged naturally, so it is safe to shorten the pre-purge time. There is no problem above. As a matter of course, when the detected temperature is low, the pre-purge time can be extended to ensure sufficient safety.

According to the second aspect of the present invention, in the pre-purge time, the operating interval (pre-purge time) between the burner fan and the ignition device is kept constant, while the operating interval (pre-purge time) between the ignition device and the fuel supply means is set. It is possible to make the ignition time) largely change according to the detected temperature, and it is possible to shorten the pre-purge time as much as possible while preventing the fuel from adhering to the ignition device.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a water heater to which the present invention is applied. In FIG. 2, reference numeral 1 denotes a water heater main body installed outdoors under the eaves, and the water heater main body 1 has a combustion chamber 2,
Water chamber 3, exhaust chamber 4 and flue 5 with a capacity of about 20 liters
A heat exchanger 6 made up of: a burner 7 as a heat source facing the combustion chamber 2;

Further, 9 is a water supply pipe connected to the water chamber 3 slightly above the upper wall of the combustion chamber 2, 10 is a hot water supply pipe connected to the upper portion of the water chamber 3, and 11 is combustion collected in the exhaust chamber 4. An exhaust top for discharging the exhaust gas to the atmosphere, and a temperature detector 12 for detecting the water temperature of the water chamber 3 between the water supply pipe 9 and the hot water supply pipe 10. A hot water supply pipe 10 led out from the water heater main body 1 is connected to a faucet 13 installed in an indoor kitchen, a washroom or the like.
A remote controller 14 is provided near the faucet 13, and the remote controller 14 is connected to the control device 8 by a remote controller line 15.

FIG. 1 shows a specific example of the control device 8 for the hot water supply device described above. In FIG. 1, reference numeral 16 is a microcomputer (hereinafter, referred to as a microcomputer) for controlling the burner 7 as a heat source, and an operation switch 17 and a temperature setter 18 of the remote controller 14 and a temperature detector 12 are provided on the input side of the microcomputer 16. , And a flame detector 19 are provided. A burner fan 20, an ignition device 21, and a fuel supply pump (fuel supply means) 22 that constitute the burner 7 are provided on the output side of the microcomputer 16.

The microcomputer 16 controls the start / stop of the burner 7 as shown in FIGS. 3 to 6 while the operation switch 17 is turned on. That is, the microcomputer 16 reads the detected temperature T of the temperature detector 12 for example every 1 second as shown in FIG. 3, and stores it. In addition, by obtaining the difference between this detected temperature data and the previous detected temperature data, the temperature gradient Δ
T is detected. When the absolute value of the temperature gradient ΔT is a predetermined value (for example, 0.5 deg ° C./second) or more,
The start / stop control of the burner 7 is performed differently when the value is less than the predetermined value.

Since the water temperature of the water chamber 3 is low at the beginning of turning on the operation switch 17, the microcomputer 16 issues a thermo-on signal to operate the burner 7 in the following order. First, as shown in FIG. 4, the burner fan 20 is operated to start the pre-purge of the burner 7, and in the case of using kerosene as fuel, the oil attached to the ignition device 21 is scattered. Next, after activating the ignition device 21, the fuel supply pump 22 is activated.

The interval from the start of the operation of the burner fan 20 to the start of the operation of the fuel supply pump 22 is the pre-purge time, but in the present embodiment, the operation interval between the burner fan 20 and the ignition device 21 (pure purge time) in this pre-purge time. The prepurge time) is constant (for example, 2 seconds), and the operation interval (pre-ignition time) between the ignition device 21 and the fuel supply pump 22 is variable (for example, 3 to 8 seconds) according to the detected temperature T. That is, as shown in Table 1, the pre-ignition time is the longest (8 seconds) when the detected temperature T is lower than 22 ° C., and when the detected temperature T is 22 ° C. or higher, the pre-ignition time is 0.5 to 5 than the longest time. It is designed to be shortened by 0.0 seconds.

[0016]

[Table 1]

At the beginning of turning on the operation switch 17, the detected temperature T
, The pre-ignition time is usually the longest of 8 seconds. Therefore, the pre-purge time is 10 seconds, and the pre-purge of the burner 7 is sufficiently performed. When the fuel supply pump 22 operates, the burner 7 ignites the mixture of fuel and air and starts combustion. When ignition is detected by the signal from the flame detector 19, the microcomputer 16 continues the operation of the ignition device 21 for a predetermined time (post ignition time) and then stops it.

In the water chamber 3 having a relatively small capacity, the water temperature rises rapidly except when tapping water. In this case, since the positive temperature gradient of the detected temperature T of the temperature detector 12 becomes a predetermined value or more, as shown in FIG. 5, the microcomputer 16 causes the detected temperature T to be lower than the OFF set temperature TS2 (TS2-ΔT ×). At the time of 5), a thermo-off signal is issued to stop the burner 7. That is, the burner 7 is stopped at the time when the detected temperature T is predicted to reach the OFF set temperature TS2 after 5 seconds when viewed from the temperature gradient (positive). Therefore, the water chamber 3
There is no concern that the water temperature in the above will significantly exceed the OFF set temperature TS2.

Of course, the temperature gradient ΔT, such as during tapping
6 is smaller than the predetermined value, the microcomputer 16 continues the operation of the burner 7 until the detected temperature T reaches the off set temperature TS2, as shown in FIG. 6, so that the burner 7 may stop during continuous hot water discharge. Absent. Further, when the burner 7 is stopped, post-purge is performed as shown in FIG. 4 to prepare for the next operation of the burner 7.

When hot water is discharged while the burner 7 is stopped, new water is replenished from the water supply pipe 9 to the water chamber 3, so that the temperature detected by the temperature detector 12 drops sharply. Also in this case, since the absolute value of the negative temperature gradient ΔT of the temperature detected by the temperature detector 12 becomes equal to or larger than the predetermined value, the microcomputer 16 sets the detected temperature T higher than the ON set temperature TS1 (TS1-ΔT × 5). When it becomes, the thermo-on signal is issued and the burner 7 is operated. That is, the burner 7 is operated at the time when the detected temperature T is predicted to reach the ON set temperature TS1 after 5 seconds when viewed from the temperature gradient (negative). Therefore, the water chamber 3
There is no concern that the water temperature will fall significantly below the set temperature.

Of course, when the absolute value of the negative temperature gradient ΔT is small, such as when the hot water is stopped, the microcomputer 16 operates the burner 7 when the detected temperature reaches the ON set temperature TS1.

When the burner 7 is repeatedly started and stopped by the thermo-off and thermo-on signals as described above, the water temperature of the water chamber 3 is high, so that the pre-purge time for operating the burner 7 becomes short. When the water temperature in the water chamber 3 is high, the fuel remaining in the burner 7 is easily discharged naturally, and sufficient pre-purge is performed when the operation switch 17 is turned on.
There is no safety problem even if the prepurge time is shortened. Moreover, the pre-purge time is shortened only by the pre-ignition time, and the pure pre-purge time is always constant, so there is no concern that ignition will be performed with oil attached to the ignition device 21.

The pre-purge time should not be shortened in the case of the freeze prevention operation which is performed with the operation switch 17 in the off state, or in the case of the recycling operation when the fire is extinguished halfway. Further, the post-purge time may be shortened together with the pre-purge time.

[0024]

Since the present invention is constituted as described above, the pre-purge time is changed according to the water temperature of the heat exchanger, and when the water temperature of the heat exchanger is low as at the beginning of the operation, the pre-purge time is changed. While ensuring safety for a long time, when the burner repeatedly starts and stops due to intermittent hot water discharge, the pre-purge time can be shortened to prevent the hot water discharge temperature from dropping.

Further, according to the second aspect of the present invention, of the pre-purge time, the pure pre-purge time is made constant, and the pre-ignition time is changed according to the water temperature of the heat exchanger. It is possible to prevent adhesion and further improve safety, while suppressing a drop in tapping temperature due to intermittent tapping.

[Brief description of drawings]

FIG. 1 is a block diagram of a controller of a water heater showing an embodiment of the present invention.

FIG. 2 is a schematic structural explanatory view showing an example of a water heater.

FIG. 3 is a flowchart for explaining the operation of the control device.

FIG. 4 is a time chart for explaining the operation of the control device.

FIG. 5 is an explanatory diagram showing a temperature control characteristic of a control device.

FIG. 6 is an explanatory diagram showing another temperature control characteristic of the control device.

[Explanation of symbols]

 1 water heater main body 3 water chamber 6 heat exchanger 7 burner (heat source) 8 control device 9 water supply pipe 10 hot water supply pipe 12 temperature detector 16 microcomputer (burner control means) 20 burner fan 21 ignition device 22 fuel supply pump (fuel supply) means)

Claims (2)

[Claims] 1. A water heater including a burner, a heat exchanger for exchanging heat between combustion gas and water of the burner, and a water supply pipe and a hot water supply pipe connected to the heat exchanger, wherein the water temperature of the heat exchanger is A burner control means for starting and stopping the burner according to the set temperature determined by the temperature setter and the detected temperature of the temperature detector, and the burner control means. When the temperature detected by the temperature detector is lower than the set temperature, the burner is operated in the order of the burner fan, the ignition device and the fuel supply means, and
A controller for a water heater, which is configured to change an operation interval (pre-purge time) between the burner fan and the fuel supply means according to a temperature detected by a temperature detector. 2. A water heater comprising a burner, a heat exchanger for exchanging heat between combustion gas of the burner and water, and a water supply pipe and a hot water supply pipe connected to the heat exchanger. A burner control means for starting and stopping the burner according to the set temperature determined by the temperature setter and the detected temperature of the temperature detector, and the burner control means. When the temperature detected by the temperature detector is lower than the set temperature, the burner is operated in the order of the burner fan, the ignition device and the fuel supply means, and
A controller for a water heater, which is configured to change an operation interval (pre-ignition time) between an igniter and a fuel supply unit according to a temperature detected by a temperature detector.