JP5410934B2 - Water heater - Google Patents

Description

  The present invention relates to a water heater provided with a burner, a heat exchanger heated by the burner, a water amount sensor that detects a flow rate of water flowing into the heat exchanger, and a control unit that controls combustion of the burner.

  Conventionally, in this type of hot water heater, when the flow rate detected by the water amount sensor is less than a predetermined lower limit flow rate set for preventing emptying, combustion of the burner is prohibited by the control means, and the heat exchanger by emptying To prevent damage.

  By the way, in recent years, a one-lever hot and cold water mixing tap in which the mixing ratio of hot water and water from a water heater is variable according to the lever position has become widespread as a hot water tap installed in a kitchen or a washroom. This hot and cold water mixing tap has an advantage that hot water at a desired temperature can be discharged by adjusting the lever position. However, even when using a small amount of water, such as adding water to a toothbrush, it is often opened without changing the lever position to the hot water side. In this case, the hot water supply operation with the hot water heater is started by opening the hot and cold water mixing plug, and the hot water is stopped when the hot water reaches the middle of the pipe, which is against the demand for energy saving.

  Therefore, conventionally, a hot water heater with improved energy saving is disclosed in Patent Document 1. The water heater determines whether or not the current time is winter based on a calendar function provided in the control means. If the current time is winter, the water flow sensor detects a predetermined minimum flow rate that is set to be approximately equal to the lower limit flow rate. After the first set time (for example, 1 second) set relatively short after the operating flow rate (for example, 3 L / min) is reached, the burner is ignited to start the hot water supply operation. A hot water supply operation is started by igniting the burner after the elapse of a second set time (for example, 30 seconds) set relatively long after the detected flow rate of the sensor becomes equal to or higher than the minimum operating flow rate.

  However, in this case, in the winter season, the hot water supply operation is started in a short time after opening the hot and cold water mixing tap, so even when a small amount of water is used, the hot water supply operation is performed, which wastes energy. There is a defect that occurs. Also, when using a shower in the summer, etc., the hot water supply operation will not start until the second set time has elapsed since the start of shower use. At the same time, a large amount of water is wasted, resulting in a waste of water resources and contrary to environmental protection requirements.

JP 2007-1113889 A

  In view of the above, the present invention provides a water heater that can make a user feel uncomfortable and avoid waste of water as much as possible, and can also save energy. Is the issue.

  In order to solve the above-described problems, the present invention includes a burner, a heat exchanger heated by the burner, a water amount sensor that detects a flow rate of water to the heat exchanger, and a control unit that controls combustion of the burner. In the water heater in which the burner burn is prohibited by the control means when the detection flow rate of the water amount sensor is less than a predetermined lower limit flow rate set to prevent emptying, the control means has a lower limit of the detection flow rate of the water amount sensor. When it is less than the predetermined hot water supply requirement determination amount set larger than the flow rate, combustion of the burner is prohibited until the integrated value of the detected flow rate of the water amount sensor reaches a predetermined value, and when the integrated value exceeds the predetermined value, the burner is The hot water supply operation is started by ignition, and when the flow rate detected by the water amount sensor is equal to or greater than the hot water supply request determination amount, the burner is immediately ignited to perform control to start the hot water supply operation.

  According to the present invention, by setting the hot water supply request determination amount according to, for example, the amount of hot water when using the shower, it is immediately determined that a hot water supply request is made at the start of use of the shower, and the hot water supply operation is started. It can avoid unpleasant feelings and waste of water. Furthermore, when the detected flow rate of the water amount sensor is equal to or greater than the lower limit flow rate and less than the hot water supply determination amount, the hot water supply operation is started when the integrated value of the detected flow rate exceeds a predetermined value. The waiting time is shortened, and it is possible to avoid unpleasant feelings and waste of water as much as possible. Conversely, when the detected flow rate is small, the waiting time until the hot water supply operation is started becomes long, so when using a small amount of water such as adding water to the toothbrush, there is a high probability that the hot water supply operation will not be started, thus saving energy. You can plan.

  By the way, at the end of the hot water supply operation, the hot water heated by the heat exchanger remains in the pipe and the heat exchanger between the hot water tap made of hot water and the like and the heat exchanger. And if the tap is opened before this hot water cools down, if the start of the hot water supply operation is delayed, heat is taken away from the piping and heat exchanger by passing cold water, causing energy loss, At the beginning of operation, the combustion amount of the burner is increased by temperature control, which is against the demand for energy saving.

  Therefore, the control means performs control to immediately ignite the burner and start the hot water supply operation when the detected flow rate of the water amount sensor exceeds the lower limit flow rate until a predetermined set time has elapsed since the end of the previous hot water supply operation. Desirably configured to do. According to this, when repeated opening and closing of the hot water tap in a short time, even if the detected flow rate of the water amount sensor is less than the hot water supply request determination amount, it is determined that the hot water supply is required, Since the operation is started, it is possible to suppress the loss of heat due to the passage of cold water from the pipes and the heat exchanger, thereby contributing to energy saving. Furthermore, when a relatively small amount of hot water is repeated for face washing or the like, the hot water is discharged without delay by opening the hot water tap, and it is possible to more effectively prevent the user from feeling uncomfortable.

Explanatory drawing which shows the structure of the water heater of embodiment of this invention. The flowchart which shows the control content of the energy saving mode performed with the water heater of embodiment.

  Referring to FIG. 1, reference numeral 1 denotes a water heater main body, and the main body 1 includes a combustion housing 2. In the combustion housing 2, a lower burner 3 and an upper heat exchanger 4 heated by the burner 3 are accommodated. An electromagnetic on-off valve 6 and an electromagnetic proportional valve 7 are interposed in the gas supply path 5 for supplying fuel gas to the burner 3. A combustion fan 8 that supplies combustion air is connected to the lower end of the combustion housing 2, and an exhaust cylinder 2 a is connected to the upper end of the combustion housing 2.

  The heat exchanger 4 is connected to an upstream water supply channel 4a and a downstream hot water supply channel 4b. A water amount sensor 9 that detects a flow rate of water flow to the heat exchanger 4 and a water amount adjustment valve 10 are interposed in the water supply path 4a. Moreover, the hot water temperature sensor 11 is provided in the hot water supply path 4b. Although not shown, the hot water outlet 4b is connected to a hot water tap such as a hot and cold water mixing tap installed in a kitchen, a washroom, and a bathroom.

  Detection signals from the water amount sensor 9 and the hot water temperature sensor 11 are input to a controller 12 which is a control means provided in the water heater body 1. The controller 12 controls the electromagnetic on-off valve 6, the electromagnetic proportional valve 7, the combustion fan 8, and the water amount adjustment valve 10 based on the detected flow rate of the water amount sensor 9 and the detected temperature of the hot water temperature sensor 11.

  Here, the controller 12 can perform the control in the normal mode and the control in the energy saving mode, and the mode to be controlled is selected by a remote controller (not shown). Yes.

  In the normal mode, the electromagnetic on-off valve 6 is opened when the detected flow rate W of the water amount sensor 9 becomes equal to or higher than a predetermined lower limit flow rate YW1 (for example, 2.7 L / min) that is set to prevent idling. At the same time, the igniter (not shown) is operated to ignite the burner 3, and the combustion fan 8 is further operated to start the hot water supply operation. Then, after the burner 3 is ignited, temperature control for feedback control of the combustion amount of the burner 3 is performed via the electromagnetic proportional valve 7 so that the detected water temperature of the hot water temperature sensor 11 becomes the set hot water temperature set by the remote controller. . If the detected water temperature of the hot water temperature sensor 11 does not reach the set hot water temperature even if the combustion amount of the burner 3 is maximized, the water flow rate to the heat exchanger 4 is decreased by the water amount control valve 10. When the detected flow rate W of the water amount sensor 9 is less than the lower limit flow rate YW1, the burner 3 is extinguished by closing the electromagnetic on-off valve 6 and the hot water supply operation is terminated.

  Next, the energy saving mode will be described with reference to FIG. In the energy saving mode, first, in STEP1, it is determined whether or not the detected flow rate W of the water amount sensor 9 is equal to or higher than the lower limit flow rate YW1. If W ≧ YW1, the process proceeds to STEP 2 to determine whether or not a predetermined set time (for example, 30 minutes) has elapsed since the end of the previous hot water supply operation.

  If the set time has elapsed, the process proceeds to STEP 3 and it is determined whether or not the detected flow rate W of the water amount sensor 9 is equal to or greater than a predetermined hot water supply request determination amount YW2 that is set larger than the lower limit flow rate YW1. This hot water supply request determination amount YW2 is set to an amount slightly smaller than the average amount of hot water during shower use, for example, 6 L / min.

  If W <YW2, the process proceeds to STEP 4, where the integrated value ΣW (more precisely, the integrated value after W ≧ YW1) of the detected flow rate W of the water amount sensor 9 is equal to or greater than a predetermined value YΣW (for example, 3L). It is determined whether or not. When ΣW ≧ YΣW, the process proceeds to STEP 5 to ignite the burner 3 and start the hot water supply operation.

  When it is determined in STEP 3 that W ≧ YW, the process proceeds directly to STEP 5 to start the hot water supply operation. Further, when it is determined in STEP 2 that the set time has not elapsed since the end of the previous hot water supply operation, the process proceeds directly to STEP 5 to start the hot water supply operation. Although not shown, the temperature control is performed after the hot water supply operation is started in the same manner as in the normal mode.

  As described above, in the energy saving mode, when the detected flow rate W of the water amount sensor 9 is not less than the lower limit flow rate YW1 and less than the hot water supply request determination amount YW2, the hot water supply operation is started when the integrated value ΣW of the detected flow rate W becomes not less than the predetermined value YΣW. Therefore, when the detected flow rate W is small, the waiting time until the hot water supply operation is started becomes long. Therefore, when using a small amount of water such as adding water to the toothbrush, the probability that the hot water supply operation is not started increases, and energy saving can be achieved.

  Even if the detected flow rate W of the water amount sensor 9 is equal to or higher than the lower limit flow rate YW1 and less than the hot water supply request determination amount YW2, the waiting time until the hot water supply operation starts becomes shorter as the detected flow rate W increases. Furthermore, when the detected flow rate W becomes equal to or greater than the hot water supply request determination amount YW2 due to shower use or the like, the hot water supply operation is immediately started. Therefore, it is possible to avoid as much as possible the waste of water caused by making the user feel uncomfortable and causing the water to flow unnecessarily during the waiting time.

  By the way, at the end of the hot water supply operation, hot water heated by the heat exchanger 4 remains in the hot water outlet 4b and the heat exchanger 4. And if the tap is opened before the hot water cools down, if the start of the hot water supply operation is delayed, the heat is taken away from the hot water supply passage 4b and the heat exchanger 4 by passing cold water, and energy loss is reduced. As a result, the combustion amount of the burner 3 is increased by the temperature control at the beginning of the hot water supply operation, which is against the demand for energy saving.

  On the other hand, in this embodiment, when opening and closing of the hot water tap is repeated in a short time, even if the detected flow rate W of the water amount sensor 9 is less than the hot water supply request determination amount YW2, the hot water supply is immediately opened by opening the hot water tap. Since the operation is started, it is possible to suppress the loss of heat due to the passage of cold water from the hot water outlet 4b and the heat exchanger 4, thereby contributing to energy saving. Furthermore, when a relatively small amount of hot water is repeated at a time for facial washing or the like, the hot water is discharged without delay by opening the hot water tap, which can more effectively prevent the user from feeling uncomfortable.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to this. For example, in the above embodiment, the normal mode and the energy saving mode can be selected as the control mode, but only the control in the energy saving mode may be performed. In addition, the set time serving as a discrimination criterion in STEP 2 can be varied according to the feed water temperature or the outside air temperature so that the set time becomes shorter as the feed water temperature or the outside air temperature becomes lower.

  DESCRIPTION OF SYMBOLS 3 ... Burner, 4 ... Heat exchanger, 9 ... Water quantity sensor, 12 ... Controller (control means).

Claims (2)

A burner, a heat exchanger heated by the burner, a water amount sensor for detecting the flow rate of water to the heat exchanger, and a control means for controlling the combustion of the burner are provided, and the detection flow rate of the water amount sensor prevents emptying. When the flow rate is less than a predetermined lower limit flow rate set for the purpose,
The control means prohibits burner combustion until the integrated value of the detected flow rate of the water amount sensor reaches a predetermined value when the detected flow rate of the water amount sensor is less than a predetermined hot water supply request determination amount set larger than the lower limit flow rate. When the value exceeds a predetermined value, the burner is ignited to start the hot water supply operation. When the detected flow rate of the water amount sensor is equal to or greater than the hot water supply request determination amount, the burner is immediately ignited and the hot water supply operation is started. A water heater characterized by being configured to.   The control means immediately starts the hot water supply operation by igniting the burner when the detected flow rate of the water amount sensor becomes equal to or higher than the lower limit flow rate until a predetermined set time has elapsed since the end of the previous hot water supply operation. The water heater according to claim 1, wherein the water heater is configured to perform control.

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