JP5771235B2 - Water heater - Google Patents

Description

  The present invention relates to a hot water supply apparatus capable of performing an anti-freezing operation so that water in a water passage does not freeze.

  The water heater is provided with a heater that warms the water passage so that water in the water passage does not freeze in winter. When the atmospheric temperature detected by the atmospheric temperature sensor falls below a predetermined threshold temperature, an anti-freezing operation such as turning on the heater or operating a pump that circulates water in the water passage is performed. .

  In a hot water supply apparatus that performs such anti-freezing operation, if the atmospheric temperature sensor is broken, the anti-freezing operation cannot be started at an appropriate timing. Therefore, a technique has been proposed in which an abnormality such as a disconnection or a short circuit is detected based on the output of the atmospheric temperature sensor, and when there is no abnormality, the freeze prevention operation is started based on the atmospheric temperature detected by the atmospheric temperature sensor. (Patent Document 1).

JP 7-239151 A

  However, with the proposed technology, it is not possible to detect abnormalities (intermediate failures) in which the detection accuracy of the atmospheric temperature sensor decreases due to poor contact that does not lead to disconnection or short circuit, or deterioration of the sensor element over time. Also, even when a disconnection or short circuit of the atmospheric temperature sensor is detected, anti-freezing operation may be started regardless of the atmospheric temperature and hot water may be supplied, so it freezes when the atmospheric temperature sensor is not normal. There was a problem that preventive operation could not be performed properly.

  The present invention has been made in response to the above-described problems in the prior art, and can detect an intermediate failure of an atmospheric temperature sensor and appropriately perform an anti-freezing operation even when the atmospheric temperature sensor is not normal. An object is to provide a hot water supply apparatus capable of performing the above.

In order to solve the above-described problems, the hot water supply apparatus of the present invention employs the following configuration. That is,
Whether to start the atmospheric temperature acquisition means for acquiring the atmospheric temperature, the water temperature acquisition means for acquiring the water temperature in the water passage connected to the heat exchanger, and the antifreezing operation for preventing freezing of the water in the water passage In a hot water supply apparatus comprising start determination means for determining whether or not,
The start determination means includes
If the difference between the atmospheric temperature acquired by the atmospheric temperature acquisition means and the water temperature acquired by the water temperature acquisition means is less than a predetermined reference value, whether or not to start the freeze prevention operation is determined based on the atmospheric temperature. Judgment
When the difference between the atmospheric temperature acquired by the atmospheric temperature acquisition means and the water temperature acquired by the water temperature acquisition means is equal to or greater than the reference value, it is determined based on the water temperature whether the anti-freezing operation is started. It is characterized by that.

  Due to the difference in heat capacity between air and water, the atmospheric temperature and the water temperature decrease first, and the water temperature decreases with a delay. For this reason, by determining the start of the freeze prevention operation based on the decrease in the atmospheric temperature, the freeze prevention operation can be started at an appropriate timing before the water freezes. However, there is a possibility that an abnormality including an intermediate failure has occurred in the atmospheric temperature acquisition means for acquiring the atmospheric temperature. Therefore, in the hot water supply apparatus of the present invention, the atmospheric temperature and the water temperature are compared, and if the difference is equal to or greater than the reference value, the start of the freeze prevention operation is determined based on the water temperature instead of the atmospheric temperature. The hot water supply system always performs the hot water supply operation with reference to the water temperature, and if there is an abnormality in the water temperature acquisition means and the correct water temperature cannot be acquired, the hot water supply operation is stopped. The means may be considered normal. Therefore, if the atmospheric temperature is outside the reference value with respect to the water temperature, it can be determined that an intermediate failure has occurred in the atmospheric temperature acquisition means. In this case, since the start of the freeze prevention operation can be determined based on the water temperature instead of the atmospheric temperature, the freeze prevention operation can be appropriately executed even when the atmospheric temperature acquisition means is not normal.

  Moreover, in the hot water supply device of the present invention described above, when the start determination means determines based on the atmospheric temperature, it determines that the freeze prevention operation starts when the temperature falls below the first threshold temperature, and determines based on the water temperature. May be determined to start the freeze prevention operation when the temperature becomes lower than the second threshold temperature higher than the first threshold temperature.

  The water temperature falls later than the atmospheric temperature. For this reason, the water temperature threshold temperature (second threshold temperature) at which the freeze prevention operation is started is set higher than the threshold temperature (first threshold temperature) at the atmospheric temperature at which the freeze prevention operation is started. Even when making a determination based on this, it is possible to match the timing for starting the anti-freezing operation with the determination based on the atmospheric temperature, and as a result, the anti-freezing operation can be started at an appropriate timing.

It is explanatory drawing which showed the internal structure of the hot water supply apparatus 1 of a present Example. It is a flowchart of anti-freezing operation control processing.

  FIG. 1 is an explanatory view showing the internal structure of the hot water supply apparatus 1 of the present embodiment. The hot water supply apparatus 1 includes a housing 10 that covers the whole, a combustion unit 100 accommodated in the housing 10, a heat exchanger 120 provided in the housing 10 above the combustion unit 100, and the like.

  The combustion unit 100 includes a burner 102 that burns a mixed gas of fuel gas and combustion air, a gas passage 104 that supplies fuel gas to the burner 102, a combustion fan 110 that supplies combustion air to the burner 102, and the like. ing. A combustion can 20 is provided in the housing 10, and the burner 102 is accommodated in the combustion can 20 together with the heat exchanger 120. The gas passage 104 is provided with an electromagnetic valve 106 that opens and closes the gas passage 104 and a proportional valve 108 that controls the flow rate of the fuel gas passing through the gas passage 104. The combustion exhaust generated by the combustion in the burner 102 is sent to the upper heat exchanger 120 by the wind of the combustion fan 110 and is discharged to the outside of the housing 10 from the exhaust tube 22 provided at the upper part of the combustion can 20. .

  The heat exchanger 120 includes a plurality of heat exchange fins 122 through which combustion exhaust from the burner 102 passes, and a water pipe 124 meandering so as to penetrate the plurality of heat exchange fins 122 many times. Yes. A water supply passage 130 is connected to one end of the water conduit 124, and water is supplied to the heat exchanger 120 through the water supply passage 130. A water flow sensor 134 that detects the flow of water in the water supply passage 130 is provided in the water supply passage 130. When the water flow is detected by the water flow sensor 134, combustion of the mixed gas is started by the burner 102, so that the water flowing through the water flow pipe 124 is heated by the combustion exhaust gas passing through the heat exchanger 120 to become hot water. Further, a hot water supply passage 132 is connected to the other end of the water pipe 124, and hot water is supplied to the bath tub (not shown) through the hot water supply passage 132. The hot water supply passage 132 is provided with a hot water temperature sensor 136 that detects the temperature of the hot water going out of the hot water supply device 1 (temperature of discharged water).

  Further, the hot water supply apparatus 1 is equipped with a controller 150 for controlling the entire apparatus, and an electromagnetic valve 106, a proportional valve 108, a combustion fan 110, a water flow sensor 134, a hot water temperature sensor 136, and the like are connected to the controller 150. . The controller 150 is required by referring to the flow rate of water detected by the water flow sensor 134, the hot water supply temperature set by a remote controller (not shown), etc., in order to properly burn the mixed gas in the burner 102. The opening degree of the proportional valve 108 and the rotation speed of the combustion fan 110 are controlled according to the amount of heat.

  Further, inside the hot water supply apparatus 1 of the present embodiment, an atmospheric temperature sensor 138 that detects an atmospheric temperature and a heater 140 that warms the water supply passage 130 so that water in the water supply passage 130 does not freeze in winter or the like are provided. The atmospheric temperature sensor 138 and the heater 140 are also connected to the controller 150. And the controller 150 of a present Example is performing the following freeze prevention operation control processing in order to start the freeze prevention operation which prevents freezing of the water in the water supply path 130 at an appropriate timing. The atmospheric temperature sensor 138 of this embodiment corresponds to the “ambient temperature acquisition unit” of the present invention.

  FIG. 2 is a flowchart of the freeze prevention operation control process executed by the controller 150. In the freeze prevention operation control process, first, it is determined whether or not the hot water temperature sensor 136 is normal (STEP 100). The controller 150 confirms whether or not there is the following abnormality with respect to the hot water temperature sensor 136. The hot water temperature sensor 136 of this embodiment includes a thermistor (not shown) whose electrical resistance changes with temperature change, and determines whether there is an abnormality such as disconnection or short circuit based on the output of the thermistor. Further, the hot water supply passage 132 of this embodiment is connected to a reheating circuit (not shown) for circulating and reheating the hot water in the bath tub, and this reheating circuit is supplied to the bathtub. A bath water temperature sensor (not shown) for detecting the temperature of the hot water (bath water temperature) is provided. Since the bath water temperature during hot water filling is almost the same as the hot spring temperature, if the absolute value of the difference between the bath hot water temperature and the hot spring temperature is 7 ° C or higher, thermistor may deteriorate over time. Therefore, it is determined that an abnormality that causes a decrease in temperature detection accuracy (hereinafter, such abnormality is referred to as an intermediate failure) has occurred. When these abnormalities occur, the hot water supply operation 1 is stopped in the hot water supply device 1 because it is not possible to grasp the accurate hot water temperature and hot water may be supplied. In such a case, since it is determined in STEP 100 that the hot water temperature sensor 136 is not normal (STEP 100: no), the anti-freezing operation control process is also stopped without performing the anti-freezing operation.

  On the other hand, when the tapping temperature sensor 136 is normal (STEP 100: yes), the feed water temperature (temperature of water in the feed water passage 130) is calculated from the tapping temperature detected by the tapping temperature sensor 136 (STEP 102). . First, the controller 150 obtains the rising temperature of the water in the heat exchanger 120 based on the flow rate of water detected by the water flow sensor 134 and the amount of heat generated by the combustion in the burner 102, and the rising temperature is calculated from the tapping temperature. Subtract the water supply temperature. The tapping temperature sensor 136 and the controller 150 of this embodiment correspond to the “water temperature acquisition means” of the present invention.

  When the water supply temperature is thus calculated, the atmospheric temperature detected by the atmospheric temperature sensor 138 is acquired (STEP 104). The atmospheric temperature sensor 138 is also provided with a thermistor (not shown) similarly to the tapping temperature sensor 136, and detects the atmospheric temperature based on the output. Then, the atmospheric temperature and the water supply temperature are compared, and it is determined whether or not the absolute value of the difference is equal to or greater than a reference value (20 ° C. in this embodiment) (STEP 106). Since the change in the water supply temperature is linked to the change in the atmospheric temperature, if the difference is less than 20 ° C. (STEP 106: no), the atmospheric temperature sensor 138 is determined to be normal, and the freeze prevention operation is performed based on the atmospheric temperature. To start.

  Here, the atmospheric temperature decreases faster than the water temperature due to the difference in heat capacity. If the atmospheric temperature falls below freezing, the water temperature will probably drop below freezing, so if anti-freezing operation is started based on the decrease in atmospheric temperature, anti-freezing operation will be started at an appropriate time before water freezes. It is possible. Further, in consideration of the fact that the temperature may be lower than the surroundings in the portion where the wind hits, in this embodiment, since the threshold temperature of the atmospheric temperature at which the freeze prevention operation is started is set to 3 ° C., the atmospheric temperature It is determined whether or not the atmospheric temperature detected by the sensor 138 is less than 3 ° C. (STEP 108). If the atmospheric temperature is 3 ° C. or higher (STEP 108: no), it is determined that it is not necessary to perform the freeze prevention operation, and the process returns to STEP 100 as it is and the above-described processing is repeated. The controller 150 of this embodiment corresponds to “start determination unit” of the present invention.

  On the other hand, when the atmospheric temperature is less than 3 ° C. (STEP 108: yes), the freeze prevention operation is started (STEP 110). In the freeze prevention operation of this embodiment, the heater 140 is turned on to warm the water supply passage 130. The mode of the freeze prevention operation is not limited to this, and for example, a circulation circuit or a circulation pump may be provided in the water supply passage 130 to circulate the water in the water supply passage 130. Further, the heater 140 is not limited to one, and a plurality of heaters 140 may be provided. The heater 140 may be installed in a place where freezing is likely to occur or a place where damage is easily caused by freezing.

  When the freeze prevention operation is started, it is determined whether or not the atmospheric temperature detected by the atmospheric temperature sensor 138 has become 7 ° C. or higher (STEP 112). When the atmospheric temperature is less than 7 ° C. (STEP 112: no), the vehicle keeps on standby until the atmospheric temperature reaches 7 ° C. or higher while continuing the freeze prevention operation. And when atmospheric temperature becomes 7 degreeC or more (STEP112: yes), the heater 140 is turned off and freeze prevention operation is complete | finished (STEP114).

  In the above description, the case where the absolute value of the difference between the atmospheric temperature and the water supply temperature is less than the reference value (20 ° C.) in the determination of STEP 106 is explained, but when there is a difference of 20 ° C. or more (STEP 106: yes), An abnormality of the atmospheric temperature sensor 138 is notified (STEP 116). Here, the difference between the atmospheric temperature and the water supply temperature exceeds the reference value may be due to whether the atmospheric temperature is incorrect or the water supply temperature is incorrect. Since it is ensured that the feed water temperature calculated from the tapping temperature detected by the already tapped hot water temperature sensor 136 is correct, it can be determined that an abnormality (intermediate failure) has occurred in the atmospheric temperature sensor 138. The abnormality notification is executed by displaying an error on a display unit (not shown).

  When the abnormality is notified, it is subsequently determined whether or not the feed water temperature calculated in STEP 102 is less than 15 ° C. (STEP 118). In this embodiment, when an intermediate failure of the atmospheric temperature sensor 138 is detected, the start of the anti-freezing operation is determined based on the water supply temperature instead of the atmospheric temperature, so the anti-freezing operation is performed even if the atmospheric temperature sensor 138 is not normal. You can start when you need it. In this embodiment, since the threshold temperature of the feed water temperature for starting the freeze prevention operation is set to 15 ° C., when the feed water temperature is 15 ° C. or more (STEP 118: no), it is not necessary to perform the freeze prevention operation. It returns to STEP100 as it is.

  On the other hand, when the feed water temperature is lower than 15 ° C. (STEP 118: yes), the heater 140 is turned on and the anti-freezing operation is started (STEP 120). Since the water supply temperature decreases later than the atmospheric temperature, the threshold temperature of the water supply temperature (15 ° C.) is set higher than the above-described threshold temperature of the atmospheric temperature (3 ° C., STEP 108). Thus, even when the determination is made based on the feed water temperature, the timing for starting the freeze prevention operation can be matched with the determination based on the atmospheric temperature.

  When the freeze prevention operation is started, it is determined whether or not the feed water temperature is 17 ° C. or higher (STEP 122). In STEP 122, the feed water temperature is calculated again from the tapping temperature detected by the tapping temperature sensor 136. If the feed water temperature is less than 17 ° C. (STEP 122: no), the recalculated feed is continued while the freeze prevention operation is continued. It will be in a standby state until water temperature becomes 17 degreeC or more.

  Thereafter, when the feed water temperature becomes 17 ° C. or higher (STEP 122: yes), the heater 140 is turned off and the freeze prevention operation is ended (STEP 124). Thus, even if the atmospheric temperature sensor 138 is not normal, the end of the freeze prevention operation is determined based on the feed water temperature. Therefore, the freeze prevention operation is not continued, and the freeze prevention operation is terminated when it is no longer necessary. be able to.

  As mentioned above, although the hot water supply apparatus 1 of a present Example was demonstrated, this invention is not restricted to said Example, In the range which does not deviate from the summary, it is possible to implement in various aspects.

  For example, in the present embodiment described above, the feed water temperature is calculated from the tapping temperature detected by the tapping temperature sensor 136. However, a water supply temperature sensor may be provided in the water supply passage 130 to directly detect the water supply temperature. In this case, a plurality of feed water temperature sensors may be provided, and the detected values may be compared with each other to confirm whether or not the feed water temperature sensor is normal. And when an intermediate failure of the feed water temperature sensor is detected, the accurate feed water temperature cannot be grasped, and it cannot be determined whether the atmospheric temperature sensor 138 is normal from comparison with the atmospheric temperature. The freeze prevention operation control process may be stopped.

  Further, the atmospheric temperature sensor 138 is not necessarily installed inside the hot water supply device 1 and may be installed on the outer surface of the housing 10 or the like. If the atmospheric temperature sensor 138 is installed outside the housing 10, it is possible to detect a decrease in the atmospheric temperature more quickly than when installed inside.

DESCRIPTION OF SYMBOLS 1 ... Hot-water supply apparatus, 10 ... Housing, 20 ... Combustion can,
22 ... Exhaust tube, 100 ... Combustion part, 102 ... Burner,
104: Gas passage 106: Solenoid valve 108: Proportional valve
110 ... Combustion fan, 120 ... Heat exchanger, 122 ... Heat exchange fin,
124 ... Water pipe, 130 ... Water supply passage, 132 ... Hot water supply passage,
134: Water flow sensor, 136: Hot water temperature sensor, 138: High temperature sensor,
140 ... heater, 150 ... controller.

Claims (2)

Whether to start the atmospheric temperature acquisition means for acquiring the atmospheric temperature, the water temperature acquisition means for acquiring the water temperature in the water passage connected to the heat exchanger, and the antifreezing operation for preventing freezing of the water in the water passage In a hot water supply apparatus comprising start determination means for determining whether or not,
The start determination means includes
If the difference between the atmospheric temperature acquired by the atmospheric temperature acquisition means and the water temperature acquired by the water temperature acquisition means is less than a predetermined reference value, whether or not to start the freeze prevention operation is determined based on the atmospheric temperature. Judgment
When the difference between the atmospheric temperature acquired by the atmospheric temperature acquisition means and the water temperature acquired by the water temperature acquisition means is equal to or greater than the reference value, it is determined based on the water temperature whether the anti-freezing operation is started. A water heater characterized by that. The hot water supply apparatus according to claim 1,
The start determination means includes
When judging based on the atmospheric temperature acquired by the atmospheric temperature acquisition means, when the atmospheric temperature falls below a predetermined first threshold temperature, it is determined to start the freeze prevention operation,
When determining based on the water temperature acquired by the water temperature acquisition means, it is determined that the anti-freezing operation is started when the water temperature falls below a second threshold temperature higher than the first threshold temperature. Hot water supply device.

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