JPS613947A - Controlling device of hot-water supplier - Google Patents

Abstract

PURPOSE:To prevent the sandwich phenomena of cold water upon restarting the flowing of water by a method wherein a forced combustion of a given time is effected after a predetermined time from a time point when a flow detector has detected the flow of water in case a combustion demand, hased on the output signal of a water temperature sensor, is not leting obtained. CONSTITUTION:In the control device for hot-water supplier, in which the ignition and extinguishing of burners 3, 4 are effected to keep hot-water supplying temperature in constant utilizing the output of the flow detector 21 for detecting the flow of water for the water pipeline of a heat exchanger and the output of the water temperature sensor 5 provided on the way of the water pipeline, the device is equipped with a circuit 10 commanding the forced combustion of a given time after a predetermined time from the time point when the flow detector 21 had detected the flow of water in case the combustion demanding signal, based on the output signal of the water temperature sensor 5, has not been obtained. Thus, the sandwich phenomena of cold water, which is caused upon restarting the flowing of water, may be prevented.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a control device for an instantaneous water heater.

[Conventional technology]

Figure 6 shows the schematic structure of the instantaneous water heater. In the figure,
A fin-type heat exchanger 2 is arranged in the upper part of the combustion tube 1, and two gun-type burners 3.4 are usually arranged in the lower part. The water supply piping to the heat exchanger 2 is equipped with a flow switch 21 that turns on when it detects the flow of water to the heat exchanger 2. A thermistor 5 is provided. Burner6.
The oil supply pipes 4 are provided with solenoid valves 31 and 41, respectively. Signals from the thermistor 5° flow switch 21, etc. are sent to control port path 6. The control circuit 6 controls the opening and closing of the electromagnetic valves 31 and 41 based on these signals, and also controls the combustion blower 79, ignition heater (not shown), and the like.

This water heater can supply hot water only while Flow In-I+-21 is on. Namely.

While water supplied from the water supply pipe passes through the heat exchanger 2, it is heated in the bath 6.4 and turned into hot water, which is then supplied to a predetermined location from the hot water supply pipe. The temperature of the hot water is maintained at a set temperature by controlling the ignition and extinguishing of burners 3 and 4. Of course, this set temperature is variable.

[Problem that the invention seeks to solve]

By the way, with this type of instantaneous hot water heater, if you stop water flow and immediately restart water flow after stopping hot water supply, hot water supply will resume, but once hot water supply is restarted and a predetermined amount of hot water is produced, , a cold water sandwich phenomenon occurs in which cold water suddenly comes out and then hot water comes out, making it difficult to maintain a constant water temperature.

This will be explained with reference to FIGS. 4(a) to 4(d).

Figure 4 (a) shows the state in which hot water is being supplied, and even if the water flow is subsequently stopped, hot water remains in the heat exchanger 2 as shown in Figure 4 (b). Thermistor 5 detects a temperature higher than the set temperature.

No combustion request signal is output to the solenoid valves 31 and 41. When water flow is restarted 9 times after this, combustion does not start until the cold water comes into contact with the thermistor 5, as shown in FIG. 4(C), but hot water comes out. In FIG. 4(d), when cold water comes into contact with the thermistor 5, the thermistor 5 outputs a combustion request signal to the solenoid valves 31 and 41, and even if combustion starts, the water temperature does not rise immediately. For this reason, the remaining hot water in the water pipes will come out.) Cold water will suddenly come out, and then hot water will come out.

The purpose of the present invention is to solve these problems.

An object of the present invention is to provide a control device for a water heater that can prevent the cold water sandwich phenomenon that occurs when water flow is resumed.

[Means for solving problems]

According to the present invention, the output of the flow detector for detecting the flow of water to the water pipe of the heat exchanger and the output of the water temperature sensor provided in the middle of the water pipe are used to ignite and extinguish the burner. In a water heater control device that maintains a constant outlet temperature, when a combustion request signal based on the output signal of the water temperature sensor is not obtained, from the time the flow detector detects water flow. There is obtained a control device for a water heater characterized in that it includes a circuit that causes forced combustion to occur for a certain period of time after a certain period of time.

〔Example〕

The present invention will be explained in detail below.

FIG. 1 is a block diagram of an embodiment of the present invention, and a case where it is applied to the water heater shown in FIG. 6 will be described. Therefore, the same parts as in FIG. 6 are designated by the same reference numerals.

For fuel oil supply piping to burners 3 and 4, respectively.

A solenoid valve 31.41 is provided. Further, a thermistor 5 for detecting water temperature is provided in the intermediate piping of the heat exchanger, and a flow switch 21 is provided in the water supply piping to the heat exchanger, which turns on when water is detected to flow to the heat exchanger 2. It is being The solenoid valves 31 and 41 are controlled by the output of an AND gate 64 which receives the output of the flow switch 21 and a comparator 32 which receives a signal from the temperature setting device 63 and a signal from the thermistor 5 as inputs.

The following description will be made on the premise that the flow switch 21 provided in the water supply pipe is on. The signal corresponding to the set temperature T1 set by the temperature setting device filter 6 is compared with the water temperature detection signal obtained from the thermistor 5, and if the set temperature T1 is higher, a combustion request signal is obtained at the output of the comparator 62. , the solenoid valves 51 and 41 are opened to continue combustion. and.

When the water temperature around the thermistor 5 reaches the set temperature.

The combustion request signal is not obtained from the output of the comparator 62, and the solenoid valves 61 and 41 are closed to extinguish the fire.

Therefore, according to this device, when the flow of water in the water supply pipe is detected by the flow switch 21, the burner 3
, 4 are both ignited and combustion begins. When the water temperature in the heat exchanger rises and reaches the set temperature T1, burners 6 and 4 are extinguished. Of course.

When the flow switch 21 is turned off, the solenoid valves 51 and 41 are closed regardless of the output of the comparator 62'.

The present invention is characterized in that this device is further provided with nine forced combustion circuits 10. In this forced combustion circuit 10, when the output of the comparator 32 is decreasing (that is, when the combustion request signal is not obtained in the output of the comparator 32), the flow switch 21 detects water flow. This is a circuit that performs forced combustion of one beak-2 for a certain time after a predetermined time t1 from the time when it is turned on.

FIG. 2 shows a time chart of the operation of each part of the circuit shown in FIG. In Fig. 2, 100 is the time when the first water flow is started, 101 is the time when the water flow is started again with a small amount of water,
Reference numeral 102 indicates the point in time when water flow is started again with a large amount of water.

When the amount of water is small and water reflow is started, the low level portion of the output (■) of the comparator 62, such as the portion 106, is long.

When the amount of water is large and water recirculation is started, the low level portion of the output (2) of the comparator 52, such as the portion 104, is short. The output (■) of the forced combustion circuit 10 provides an effective pulse that causes 9 forced combustion only when water is supplied again with a small amount of water, and when water is flowing in other conditions, 9 forced combustion is performed by the AND gate 35 in Fig. 1. This prevents a pulse from being output to the output (2) of the circuit 10.

Here, as described above, tl indicates a predetermined time after the flow inch 21 detects water flow and turns on, but this predetermined time t1.

To explain with reference to the state shown in FIG. 4(C), the time period is set to the time from when the water flow is restarted with a small amount of water until the time when the cold water does not come into contact with the thermistor 5. Further, +t2 is set so that the portion of cold water sandwiched between hot water is minimized.

In such instantaneous water heaters, in actual use, the cold water sandwich phenomenon described above becomes a problem only when water flow is restarted at a small flow rate, such as when using a shower or washing hands twice. In this embodiment, it is possible to prevent the cold water sandwich phenomenon when water flow is restarted at such a small flow rate.

The forced combustion circuit 10 can be easily configured using, for example, a timer, a counter, or the like.

It goes without saying that the two-burner system can also be applied to multi-stage calorific value switching control using a plurality of burners.

〔Effect of the invention〕

As explained above, according to the second aspect of the present invention, there is provided a control device for a water heater that can prevent the cold water sandwich phenomenon that occurs when water flow is restarted.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, and is a diagram for explaining the drawbacks of the first embodiment. In the figure, 3 and 4 are burners, 5 is a thermistor, 61°41 is a solenoid valve, 32 is a comparator, 33 is a temperature setting device, and 10 is a forced combustion circuit.

Claims (1)

[Claims] 1. The burner is ignited and extinguished by using the output of a flow detector to detect the flow of water to the water pipe of the heat exchanger and the output of the water temperature sensor installed in the middle of the water pipe, and the hot water is discharged. In a water heater control device that maintains a constant temperature, when a combustion request signal based on the output signal of the water temperature sensor is not obtained, a predetermined period of time elapses after the flow detector detects water flow. A water heater control device characterized by being equipped with a circuit that causes forced combustion.