JP5942282B2 - Water heater - Google Patents

Description

  The present invention relates to a hot water supply apparatus in which an electric heater for preventing freezing is attached to a built-in water pipe.

  Since a hot water supply apparatus using a gas burner as a heat source discharges exhaust gas during operation, it is often installed outdoors rather than indoors. In this case, in particular, when the outside air temperature decreases, such as in winter, there is a possibility that the water in the built-in water pipe freezes and the water pipe ruptures when the hot water supply operation is not performed. Therefore, conventionally, an electric heater is attached to the water pipe, and the electric heater is energized in a state where the water in the water pipe may freeze, and the water in the water pipe is warmed to prevent freezing.

  Since this electric heater cannot heat the water in the water pipe when a disconnection failure or a short-circuit failure occurs, it has conventionally been provided with detection means for detecting that a disconnection failure or a short-circuit failure has occurred in this electric heater. Have been proposed (see, for example, Patent Document 1).

JP 2003-322399 A (paragraph 0004)

  In addition to the above-mentioned patent documents, there have been many proposals for detecting disconnection faults and short circuit faults of an electric heater for preventing freezing. However, an ON fault in which the electric heater operates even though the electric heater does not operate is proposed. What has been detected has never been proposed before.

  In recent years, the capacity of the electric heater tends to increase. When an ON failure occurs in the electric heater, the water temperature in the water pipe rises even if the gas burner is not operated, and the tap for hot water is opened. Unexpectedly hot water flows out in large quantities. In addition, various types of safety devices have been incorporated in the hot water supply device so far, and when hot water having unexpectedly high temperature is supplied in this way, for example, the operation of the hot water supply device is stopped to continue the hot water supply. Is not hot water. However, when the electric heater is turned on as described above, there is a problem that high-temperature hot water is supplied for a short time before stopping hot water supply.

  In view of the above problems, an object of the present invention is to provide a hot water supply device that detects an ON failure of an electric heater and does not supply hot water even in the first short time.

In order to solve the above-mentioned problems, a hot water supply apparatus according to the present invention has a water pipe built in, tap water is introduced into the water pipe from the outside, and water in the water pipe is drained by a heat exchanger provided in the middle of the water pipe. A hot water supply device that generates hot water by heating and supplies hot water from the water pipe to the outside, and is connected in series to the heat exchanger, and has a water intake variable device that restricts the flow rate in the water pipe In this case, an electric heater is attached to the water pipe to prevent the water in the water pipe from freezing in a state where the water flow in the water pipe is stopped. An ON failure detection means is provided for detecting the occurrence of an ON failure in which the heater is operating. When the ON failure detection means detects the occurrence of an ON failure , the operation of the electric heater is not forcibly stopped. Variable water volume Actuating the, and wherein the throttling the amount of water passing water pipe.

  Immediately after the ON failure occurs, there is no problem because the amount of heating by the electric heater is small. The problem arises when an ON failure occurs when the hot water is not supplied for a long time, such as at night, and the water in the water pipe is heated by the electric heater for a long time. In this case, when it is detected that an ON failure has occurred, the water amount variable device is operated to reduce the amount of water in the water pipe. In this state, when the hot water supply faucet is opened, even if hot water is supplied, a small amount of hot water flows from the hot water supply device to the faucet. Since heat is radiated from the pipe to the outside before reaching the faucet from the hot water supply device, hot water does not flow out from the faucet.

  A bypass passage that bypasses the heat exchanger is provided in the water pipe, and a hot water mixing amount variable device that increases or decreases the amount of water that bypasses the heat exchanger through the bypass passage is provided. When the occurrence of a failure is detected, if this hot water mixing amount variable device is operated to increase the amount of water passing through the bypass, the hot water heated in the hot water is mixed with a large amount of low temperature water from the hot water supply device. Since it flows out, hot water does not flow out from the faucet.

  The cause of the ON failure includes, for example, a case where the contact of the relay for supplying power to the electric heater is attracted and the contact is kept in the ON state even after the energization to the relay coil is stopped. In such an ON failure, the contact may be separated even by a small vibration and the ON failure may be released. If the ON failure is resolved, there is no problem even if the normal operation state is restored, but since warmed hot water remains in the water pipe, it is necessary to wait until the hot water cools down.

  Therefore, after the ON failure detection means detects the occurrence of an ON failure, a timer is provided that continuously detects the ON failure state and returns to the normal operation state after a predetermined time has elapsed since the ON failure was eliminated. Is desirable.

  As is apparent from the above description, the present invention reduces the amount of hot water supply or mixes a large amount of cold water with the outflowing hot water even when an ON failure occurs in the anti-freezing electric heater. Hot water is not supplied even for a short period of time.

The figure which shows the structure of one embodiment of this invention Schematic showing the internal structure of the water heater Diagram showing the structure for attaching the thermistor to the electric heater Circuit diagram for detecting the energization state of the electric heater Flow chart showing control for automatic recovery after ON failure

  1 and 2, 1 is an example of a hot water supply apparatus according to the present invention. The hot water supply apparatus 1 includes a heat exchanger 14 that uses a gas burner as a heat source, and gas is supplied to the gas burner from a gas supply port 11.

  On the other hand, the water heater 1 has a built-in water pipe 2, and the water pipe 2 is provided with an inlet 12 through which tap water flows and an outlet 13 through which hot water heated inside flows out. . The heat exchanger 14 is provided at an intermediate position of the water pipe 2.

  The water flow pipe 2 is provided with a water quantity servo 4, which is a water quantity variable device, downstream of the inlet 12 so as to be in series with the heat exchanger 14. This water amount servo 4 increases or decreases the opening degree by a signal from the control unit 6 and is normally fully open, but the opening degree is narrowed by a signal from the control unit 6 and the flow rate in the water pipe 2 is decreased. be able to.

  A bypass servo 5 which is a hot water mixing amount variable device is provided further downstream of the water amount servo 4. The bypass servo 5 adjusts the amount of water to be bypassed to the bypass path 21 and is normally in a state where the flow rate to the bypass path 21 is reduced, but the flow rate to the bypass path 21 is increased by a signal from the control unit 6. Can be made.

  A thermistor 15 is attached in the vicinity of the outlet of the heat exchanger 14 so that the temperature of the hot water flowing out of the heat exchanger 14 is detected. When the hot water temperature flowing out from the heat exchanger 14 is low, dew condensation occurs in the heat exchanger 14, so that the hot water temperature flowing out from the heat exchanger 14 is controlled to be equal to or higher than a certain temperature. For this reason, when hot water of low temperature is supplied, the bypass servo 5 is operated, and hot water flowing out of the heat exchanger 14 is mixed with hot water at a certain temperature or higher to supply hot water. The temperature of the hot water to be supplied is detected by the thermistor 16, and the operation of the hot water supply device 1 is feedback-controlled by the control unit 6 so that hot water at the set temperature flows out. The hot water supply temperature is set by a remote controller 61 connected to the control unit 6.

  In a state where no hot water is supplied, the gas burner is in a fire extinguishing state, and water in the water pipe 2 is not flowing. If the outside air temperature decreases in this state, the water in the water pipe 2 may be frozen. In view of this, the electric heaters 3 are attached to various portions of the water pipes 2, and when there is a risk of freezing, the electric heaters 3 are energized to warm the water in the water pipes 2.

  On the contrary, in the state where it is not necessary to warm the water in the water pipe 2 or in the state where the heating is stopped after being energized for a predetermined time, the electric heater 3 should not be energized. There is a risk that a so-called ON failure will occur.

  In order to detect the occurrence of this ON failure, for example, as shown in FIG. 3, a dedicated thermistor 7 is attached between the metal heater 31 for attaching the electric heater 3 to the water pipe 2 and the electric heater 3. The thermistor 7 is connected to the control unit 6. When the thermistor 7 detects that the electric heater 3 is generating heat while the energization of the electric heater 3 is supposed to be stopped, the control unit 6 is turned ON. Can be determined to have occurred. The thermistor 7 may be attached to all the electric heaters 3 or may be selectively attached to one or more electric heaters 3.

  Alternatively, occurrence of an ON failure can be detected without using such a dedicated thermistor 7. As shown in FIG. 4, the circuit is configured such that the LED 64 of the photocoupler emits light when the relay contact 63 that energizes each electric heater 3 is in the on state, and the set phototransistor when the LED 64 emits light. 65 is turned ON so that the controller 6 can detect the ON state. Since the relay coil 62 that turns on the relay contact 63 is operated by the control unit 6, if the relay contact 63 is in the ON state even though the relay coil 62 is not operated, the control unit 6 has an ON failure. Can be detected. In addition, it is possible to detect the occurrence of an ON failure from the detection temperature of the existing thermistors 15 and 16. Further, since the ON state of the relay contact can be detected by detecting the energization current of the harness that supplies power to the electric heater, the control unit can also detect that an ON failure has occurred. In any means, when the occurrence of an ON failure is detected, the control shown in FIG. 5 is performed.

  Referring to FIG. 5, it is continuously checked whether an ON failure has occurred. When the occurrence of an ON failure is detected by at least one of the above means (S1), the water amount servo 4 is operated to reduce the opening degree of the water amount servo 4. There are two types of water volume servos 4 that have a valve closing function that completely closes and those that cannot be closed completely. However, in any type, the opening degree is reduced when an ON failure occurs. did. In the case of a type having a fully closed function, the opening degree may be reduced to a fully closed state as necessary. On the other hand, when a water volume servo 4 of a type that cannot be completely closed is installed, the amount of water bypassed to the bypass passage 21 is increased by operating the bypass servo 5 in conjunction with the throttle opening of the water volume servo 4 being reduced. Let's make it. In this case, the bypass servo 5 is not necessarily operated, and may be operated as necessary. At the same time, a failure display indicating that an ON failure has occurred in the remote controller 61 is performed (S2).

  In the present embodiment, at this time, the operation of the hot water supply device 1 is stopped so that hot water supply cannot be performed until it is manually returned by a serviceman or the like. However, it may be automatically returned as described below.

  After the above failure display, the status of the ON failure is further checked, and if the ON failure is resolved, the return timer is activated (S3, S4). This is because it is considered that the temperature in the water pipe 2 is still high immediately after the ON failure is resolved. For example, the hot water in the water pipe 2 is kept on standby for about 1 hour until it is naturally cooled. When the elapsed time by the timer ends (S5), the normal operation is restored.

  In addition, this invention is not limited to an above-described form, You may add a various change in the range which does not deviate from the summary of this invention.

DESCRIPTION OF SYMBOLS 1 Water heater 2 Water pipe 3 Electric heater 4 Water quantity servo 5 Bypass servo 7 Thermistor 14 Heat exchanger 21 Bypass path 62 Relay coil 63 Relay contact

Claims (3)

A water pipe is built in, tap water is introduced into the water pipe from the outside, and heat in the water pipe is heated by a heat exchanger provided in the middle of the water pipe to generate hot water. A hot water supply device that supplies hot water and hot water that is connected in series to the heat exchanger and has a water intake variable device that restricts the flow rate in the water flow pipe, the water flow in the water flow pipe stops in the water flow pipe An electric heater is installed to prevent the water in the water pipe from freezing while the electric heater is in operation, and the electric heater is operating when the electric heater should not be operated. When a failure detection means is provided, and the ON failure detection means detects the occurrence of an ON failure, the operation of the water intake amount variable device is not operated, but the amount of water in the water flow pipe is reduced rather than forcibly stopping the operation of the electric heater. Characterized by squeezing Water heater.   A bypass passage that bypasses the heat exchanger is provided in the water pipe, and a hot water mixing amount variable device that increases or decreases the amount of water that bypasses the heat exchanger through the bypass passage is provided. 2. The hot water supply apparatus according to claim 1, wherein when the occurrence is detected, the hot water / water mixing amount varying device is operated to increase the amount of water passing through the bypass passage.   After the ON failure detection means detects the occurrence of an ON failure, a timer for continuously detecting the ON failure state and returning to a normal operation state after a predetermined time has elapsed from the time when the ON failure is eliminated is provided. The hot water supply device according to claim 1 or 2, characterized in that

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