Combustion device

Abstract

The present invention provides a combustion device that can effectively prevent explosive ignition in the event of a fuel gas leak by simple means. [Solution] The combustion device C comprises an outer casing 19, a combustion device main body Ca having a combustion chamber 29 with a burner section 2 for burning fuel gas and an exhaust passage 28, a fan 1 capable of supplying air from inside the outer casing 19 to the combustion chamber 29 and exhaust passage 28, and a control means 5 that learns the combustion operation history of the combustion device C and can predict the timing of future combustion operation of the combustion device C. When the timing of the combustion operation start of the combustion device C predicted by the control means 5 arrives within a predetermined time from the present, the fan 1 is driven while the burner section 2 remains in a non-driven combustion state, and ventilation is performed inside the outer casing 19.

Description

Technical Field

[0001] The present invention relates to a combustion device of a type that burns fuel gas and is used as a component of an instantaneous water heater or the like.

Background Art

[0002] As a specific example of a combustion device, there is one described in Patent Document 1. In the combustion device described in this document, a combustion device main body is provided inside an exterior case (housing). The combustion device main body includes a combustion chamber provided with a burner unit that burns fuel gas supplied from the outside of the exterior case, and an exhaust passage that enables exhaust gas from this combustion chamber to be discharged to the outside of the exterior case. Further, the combustion device further includes a gas leak detection sensor that can detect fuel gas leakage inside the exterior case, a gas shut-off valve that can stop the supply of fuel gas to the combustion device main body, and a ventilation fan for ventilating the inside of the exterior case. According to such a configuration, when fuel gas leakage occurs inside the exterior case, it is detected to that effect using the gas leak detection sensor, and by operating the gas shut-off valve, the supply of fuel gas to the combustion device main body can be stopped. Also, in that case, by operating the ventilation fan, the fuel gas present inside the exterior case can be exhausted to the outside of the exterior case and dissipated. As a result, it is possible to prevent a large amount of fuel gas from filling the inside of the exterior case and suppress the explosion ignition (abnormal combustion accompanied by an explosion sound) of this fuel gas.

[0003] However, in the above prior art, as described below, there was still room for improvement.

[0004] First, as a countermeasure against fuel gas leakage, it is essential to use a gas leak detection sensor. For this reason, the component cost becomes high. Also, when the sensitivity of the gas leak detection sensor decreases or a failure occurs, it becomes difficult to detect fuel gas leakage at an early stage or to detect it at all. This may cause a large amount of fuel gas to accumulate inside the exterior case. Secondly, when a fuel gas leak is detected, a ventilation fan is activated to ventilate the inside of the outer casing. However, this ventilation fan is solely for ventilating the inside of the outer casing and is not a fan for supplying combustion air to the combustion chamber of the main combustion unit. Therefore, the cost of the entire system is further increased by the need to use a separate ventilation fan. Furthermore, even when the ventilation fan is activated, it is difficult to exhaust the fuel gas present in the combustion chamber and exhaust passage of the main combustion unit to the outside of the outer casing. Consequently, there is a risk that ventilation inside the outer casing may be insufficient. Thus, in Patent Document 1, if a fuel gas leak occurs, there is a risk that a large amount of fuel gas will accumulate inside the outer casing, which could lead to explosive ignition. On the other hand, if the aforementioned fuel gas leak occurs while the combustion device is shut down, and the combustion device is then restarted, the likelihood of explosive ignition of the fuel gas increases. Therefore, it is necessary to appropriately resolve these issues.

[0005] Furthermore, as one means of realizing a low-carbon society, it is conceivable to use hydrogen or hydrogen-containing gas (hydrogen-containing gas is gas that contains hydrogen gas in the fuel) as fuel gas. However, compared to, for example, methane gas, hydrogen has a smaller molecular weight and is therefore more prone to gas leaks. In addition, it is highly flammable, and even if the amount of gas leak is small, it is prone to explosive ignition. Therefore, when using hydrogen or hydrogen-containing gas as fuel gas, the aforementioned requirements are even stronger. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 5566572 [Patent Document 2] Patent No. 5490107 [Overview of the project] [Problems that the invention aims to solve]

[0007] This invention was conceived under the circumstances described above, and its objective is to provide a combustion device that can appropriately prevent explosive ignition from occurring in the event of a fuel gas leak by simple means. [Means for solving the problem]

[0008] To solve the above problems, the present invention employs the following technical measures.

[0009] A combustion device provided by a first aspect of the present invention comprises an outer case, a combustion device main body disposed within the outer case and equipped with a combustion chamber having a burner for burning fuel gas supplied to the outer case from the outside, and an exhaust passage that allows exhaust gas from the combustion chamber to be discharged to the outside of the outer case, a fan capable of supplying air from the outer case to the combustion chamber and the exhaust passage, and a control means capable of learning the combustion operation history of the combustion device and predicting the timing of future combustion operation of the combustion device, wherein when the predicted timing of the start of combustion operation of the combustion device by the control means arrives within a predetermined time from the present, the fan is driven while the burner remains in a non-driven combustion state, and ventilation is performed inside the outer case.

[0010] This configuration yields the following effects: [First effect] According to the above configuration, the control means learns the combustion operation history of the combustion device and predicts the start time of future combustion operations. At a predetermined time before the predicted start time of combustion operations arrives, ventilation of the outer casing is performed using a fan. Therefore, even if a malfunction such as a fuel gas leak occurs inside the outer casing before the predicted start time of combustion operations arrives, by the time combustion operations start, the leaked fuel gas is discharged to the outside of the outer casing, ensuring that no fuel gas accumulates inside the outer casing. As a result, when combustion operations start at the time predicted by the control means, it is possible to prevent explosive ignition of fuel gas accumulated inside the outer casing, thereby enhancing safety. [Second effect] In the combustion apparatus according to the present invention, it is possible to have a configuration that includes a gas leak detection sensor, similar to the conventional technology, but such a sensor is not essential. Therefore, it is possible to reduce the overall cost of the apparatus by omitting the sensor. Furthermore, there are no problems such as the intended function of the present invention not being achieved due to sensor failure. [Third effect] In this invention, ventilation of the outer casing using a fan is performed by supplying air from the fan to the combustion chamber and exhaust passage of the combustion device body. Therefore, if fuel gas is present in the combustion chamber and exhaust passage, this fuel gas can also be properly discharged to the outside of the outer casing. Thus, ventilation of the outer casing can be performed more sufficiently than in the conventional technology, further enhancing the effect of preventing explosion and ignition. Furthermore, since the fan used to supply combustion air to the burner can be used, there is no need to provide a fan specifically for ventilation of the outer casing. Therefore, it is possible to simplify the overall configuration of the device and further reduce the overall cost of the device.

[0011] A combustion apparatus provided in a second aspect of the present invention comprises an outer casing and a burner disposed within the outer casing for burning fuel gas supplied into the outer casing from the outside. The combustion device is characterized by comprising: a combustion chamber provided with a section and an exhaust passage that allows exhaust gas from the combustion chamber to be discharged to the outside of the outer casing; a fan capable of supplying air from inside the outer casing to the combustion chamber and the exhaust passage; and a control means that causes the fan to be driven while the burner section is in a non-driven combustion state, thereby intermittently performing ventilation inside the outer casing at predetermined time intervals.

[0012] This configuration yields the following effects: In other words, during non-combustion operation of the combustion device, ventilation of the outer casing is performed using a fan at predetermined time intervals. Therefore, compared to cases where such ventilation is not performed, if a fuel gas leak occurs inside the outer casing, the accumulation of a large amount of fuel gas inside the casing is suppressed. Furthermore, this makes it possible to reduce the possibility of combustion operation starting at a time when a large amount of fuel gas has accumulated inside the outer casing. As a result, it is possible to suppress the explosive ignition of the fuel gas accumulated inside the outer casing and enhance safety. According to the above configuration, the second and third effects previously described for the combustion device provided by the first aspect of the present invention can also be obtained.

[0013] A combustion device provided by a third aspect of the present invention comprises an outer case, a combustion device main body disposed within the outer case and equipped with a combustion chamber having a burner for burning fuel gas supplied to the outer case from the outside, and an exhaust passage that allows exhaust gas from the combustion chamber to be discharged to the outside of the outer case, a fan capable of supplying air from the outer case to the combustion chamber and the exhaust passage, and a control means capable of inputting and setting data regarding the planned start time of future combustion operation of the combustion device, wherein when the planned start time of combustion operation set in the control means arrives within a predetermined time from the present, the fan is driven while the burner remains in a non-driven combustion state, and ventilation is performed inside the outer case.

[0014] According to such a configuration, the following effects can be obtained. According to the above configuration, for example, when a user inputs and sets data regarding the scheduled start time of a future combustion operation to the control means, ventilation inside the exterior case using a fan is performed at a predetermined time before the scheduled arrival time of the start of the combustion operation. Therefore, even if a problem occurs where fuel gas leakage occurs inside the exterior case before the scheduled arrival time of the start of the combustion operation, at the time when the combustion operation is started, the leaked fuel gas can be discharged to the outside of the exterior case, and the state where no fuel gas accumulates inside the exterior case can be achieved. As a result, when the combustion operation is started at the scheduled time, it is possible to prevent the explosive ignition of the fuel gas accumulated inside the exterior case, and it is possible to enhance safety. According to the above configuration, the second and third effects already described for the combustion device provided by the first aspect of the present invention can also be obtained.

[0015] In the present invention, preferably, the ventilation inside the exterior case is performed such that the ventilation volume is equal to or greater than the volume of the exterior case.

[0016] According to such a configuration, it is more preferable in preventing the remaining of the leaked fuel gas inside the exterior case even though the ventilation inside the exterior case is performed so as not to cause insufficient ventilation.

[0017] In the present invention, preferably, an additional exhaust passage provided outside the exterior case communicating with the exhaust passage is further provided, and the ventilation inside the exterior case is performed such that the ventilation volume is equal to or greater than the sum of the volume of the exterior case and the volume of the additional exhaust passage.

[0018] According to such a configuration, when the ventilation inside the exterior case is performed, it is possible to appropriately avoid the occurrence of insufficient ventilation volume.

[0019] In the present invention, preferably, the control means further includes data input means capable of inputting and setting data related to the ventilation volume. When ventilation is performed inside the exterior case, ventilation with a ventilation volume corresponding to the data related to the ventilation volume input and set in the control means is performed.

[0020] According to such a configuration, considering various conditions such as the volume of the exterior case, etc., the ventilation volume of the ventilation inside the exterior case can be set to an appropriate value with no excess or shortage, or with little excess or shortage. It is possible to avoid the ventilation inside the exterior case being executed wastefully for a long time or causing insufficient ventilation.

[0021] In the present invention, as the fuel gas, hydrogen or a hydrogen-containing gas can be used. As described above, hydrogen or a hydrogen-containing gas has a small molecular weight and is likely to cause gas leakage. In addition, it is easily ignited, and even when the gas leakage amount is small, explosion ignition is likely to occur. On the other hand, according to the present invention, as described above, since it has an excellent explosion ignition prevention effect against fuel gas leakage, it can also be suitably dealt with when using hydrogen or a hydrogen-containing gas as the fuel gas.

[0022] Other features and advantages of the present invention will become more apparent from the following description of the embodiments of the invention with reference to the accompanying drawings.

Brief Description of the Drawings

[0023] [Figure 1] It is a schematic explanatory diagram showing an example of a hot water device equipped with a combustion device according to the present invention. [Figure 2] It is a flowchart showing an example of an operation procedure executed in a hot water device equipped with the combustion device shown in FIG. 1. [Figure 3] It is a flowchart showing a part of another example of an operation procedure executed in a hot water device equipped with the combustion device shown in FIG. 1. [Figure 4]This flowchart shows some other examples of the operating procedures performed in a hot water system equipped with the combustion device shown in Figure 1. [Modes for carrying out the invention]

[0024] Preferred embodiments of the present invention will be described in detail below with reference to the drawings.

[0025] The hot water system WH shown in Figure 1 is a hot water supply system and includes a combustion unit C, a heat exchanger 11, and a hot water supply piping section B. The combustion device C is configured, for example, as a fully primary air combustion type combustion device, and the combustion device main body Ca, premixing device 3, fan 1, and control unit 5 (an example of a control means as defined in this invention) are housed in an outer casing 19.

[0026] Fan 1 draws air from inside the outer casing 19 through the intake port 1a and can discharge this drawn-in air from the discharge port 1b toward the premixing device 3. The outer casing 19 is a case that surrounds and protects the main part of the combustion device C, and is equipped with an air intake port (not shown) for allowing outside air to flow into the outer casing 19 when fan 1 is running. The premixing device 3 is a device that mixes air supplied from the fan 1 with fuel gas supplied from outside the outer casing 19 via a gas pipe 30 equipped with a main valve (on-off valve) V2 and a pressure equalizing valve (zero governor) V1. This premixing device 3 uses, for example, the negative pressure when air passes through a predetermined flow path within the premixing device 3 to draw fuel gas into the flow path and mix it with the air. The specific configuration of such a premixing device 3 is known. Therefore, I will omit that explanation. The fuel gas is, for example, hydrogen or a hydrogen-containing gas, but is not limited to this; it can be other types of gas such as natural gas or LPG.

[0027] The combustion device main body Ca comprises a boiler body 10 that forms a combustion chamber 29 inside which a burner unit 2 is provided, and an exhaust duct 12 connected to the boiler body 10. The inner region of the exhaust duct 12 is an exhaust passage 28 that communicates with the combustion chamber 29. The fuel gas and air mixture generated in the premixing device 3 is supplied into the boiler body 10 from its upper side by the blowing action of the fan 1 and reaches the burner section 2 of the combustion chamber 29. The burner section 2 is equipped with a porous plate 21 having a plurality of vent holes 20 (flame holes). The mixture passes through the plurality of vent holes 20 and is ignited by the spark plug 22 below the porous plate 21 and burns. The combustion gas from this combustion acts on the heat exchanger 11, and the hot water passing through the heat exchanger 11 is heated. The heat exchanger 11 is equipped with primary and secondary heat exchange sections 11A and 11B for sensible heat recovery and latent heat recovery, respectively, but it is also possible to have a configuration that is different, for example, equipped only with the heat exchange section 11A for sensible heat recovery. Reference numerals 11a and 11b indicate the inlet and outlet of the hot water in the heat exchanger 11, respectively.

[0028] The hot water supply piping section B includes an inlet 70 that sends hot water entering from the outside at the inlet 73 to the heat exchanger 11, an outlet 71 that guides the hot water discharged from the heat exchanger 11 to the outlet 74, a bypass 72, and a flow path switching valve V3. Hot water can be supplied to the desired hot water destination from the outlet 74. The inlet 70 is equipped with a flow sensor Sa to determine whether the hot water flow rate of the heat exchanger 11 is equal to or greater than a predetermined minimum operating flow rate (MOQ-ON). When the hot water flow rate is equal to or greater than the minimum operating flow rate, the burner section 2 is put into a driven combustion state.

[0029] During combustion operation of the combustion device C, the combustion gas, whose heat has been recovered by the heat exchanger 11, passes through the exhaust passage 28 and is exhausted as exhaust gas to the outside of the outer casing 19 from the exhaust port 28a at its end. Furthermore, when the combustion device C is in a non-combustion operating state (main valve V2 is closed), if the fan 1 is driven, the air discharged from the fan 1 passes directly through the premixing device 3, through the combustion chamber 29 and exhaust path 28, and is exhausted to the outside of the outer casing 19. At that time, the fan 1 draws outside air from the outer casing 19 into the outer casing 19 through the aforementioned air intake hole (not shown). Therefore, if the fan 1 is driven while the burner unit 2 is in a non-driven combustion state, "ventilation of the outer casing 19" occurs.

[0030] An additional exhaust duct 12A, which has an additional exhaust passage 28A formed inside, can be connected to the exhaust duct 12, as shown by the dashed line in Figure 1. This additional exhaust duct 12A serves to guide and discharge combustion gases outdoors, for example, when the combustion device C is installed indoors.

[0031] The control unit 5 is configured using a microcomputer and performs operational control and data processing for each part of the hot water system WH (including the combustion unit C). Furthermore, as will be described later, it also controls ventilation inside the outer casing 19 by driving fan 1 to address fuel gas leaks. However, the details of this will be described later. A remote control 5A, which is installed in the kitchen or bathroom, is connected to the control unit 5 via communication. This remote control 5A includes a display unit 50 capable of displaying various data, and an operation unit 51 that includes multiple operation switches. The operation unit 51 allows the control unit 5 to input and set data related to the ventilation rate, which will be described later, and corresponds to an example of a "data input means" as defined in this invention.

[0032] Next, an example of operation control in the hot water system WH equipped with the combustion device C described above, and its operation, will be explained with reference to the flowchart in Figure 2.

[0033] First, the control unit 5 learns the past operating history of the combustion device C and has a function to predict when future combustion operation will start, and it performs such predictions almost constantly at predetermined short intervals (S1). Next, the control unit 5 determines whether the predicted time for the start of combustion operation will arrive within a predetermined time Ta from the present time, and if it does, it immediately drives the fan 1 to start ventilation inside the outer casing 19 (S2: YES, S3). At this time, the burner unit 2 remains in a non-driven combustion state. The predetermined time Ta is, for example, a time that is appropriately longer than the time required for ventilation inside the outer casing 19, and with such a time, it is possible to end the ventilation inside the outer casing 19 by an appropriate time before the predicted time for the start of combustion operation. However, the predetermined time Ta is not limited to this, and it can also be configured to be able to be increased or decreased as appropriate by operating the operation unit 51.

[0034] The ventilation inside the outer casing 19 described above ends when the ventilation volume reaches a predetermined ventilation volume (S4:YES, S5). Here, the predetermined ventilation volume is set to be equal to or greater than the volume of the outer casing 19, for example, about twice the volume of the outer casing 19. With this configuration, insufficient ventilation can be prevented. Whether or not the ventilation volume has reached the predetermined ventilation volume can be accurately determined by the control unit 5 based on the operating time (and operating speed) of the fan 1. Furthermore, if an additional exhaust passage 28A, indicated by the dashed line in Figure 1, is provided, the predetermined ventilation rate is set to be greater than or equal to the sum of the volume of the outer casing 19 and the volume of the additional exhaust passage 28A (for example, about twice the sum). Preferably, as a means to accommodate the fact that the volume of the additional exhaust passage 28A is not constant, the control unit 51 can be operated to input and set data related to the ventilation rate to the control unit 5, and the ventilation inside the outer casing 19 is configured to be performed so as to achieve the ventilation rate corresponding to this input and set data.

[0035] After ventilation of the outer casing 19 is completed, if there is an action indicating that combustion operation should be started within a predetermined time Tb, combustion operation (driven combustion of the burner section 2) is started (S6:YES, S7). Here, an action indicating that combustion operation should be started includes, for example, when a hot water flow exceeding the minimum operating flow rate occurs in the water inlet 70 (although the hot water device WH of this embodiment is not equipped with an automatic bath filling function, if this function were equipped, this would also apply when the switch for starting automatic bath filling is operated). According to the above operation control, ventilation of the outer casing 19 is performed approximately immediately before combustion operation is started, so even if fuel gas leakage occurs inside the outer casing 19, this fuel gas is discharged to the outside of the outer casing 19, and combustion operation is started when a large amount of fuel gas has not accumulated inside the outer casing 19. Therefore, explosive ignition can be prevented and safety can be enhanced. Furthermore, if the action to start combustion operation is performed after the predetermined time Tb has elapsed, rather than within the predetermined time Tb after the ventilation inside the outer casing 19 has finished, combustion operation will not be started (S6:NO,S1). This is because, if the action is performed after the predetermined time Tb has elapsed, there is a possibility that fuel gas that has leaked out since the ventilation inside the outer casing 19 has finished may have accumulated in the outer casing 19, and this action is intended to prevent ignition of such fuel gas. Furthermore, if the action to start combustion operation is performed after a predetermined time Tb has elapsed, ventilation operation inside the outer casing 19 may be performed before starting combustion operation.

[0036] Furthermore, there are cases where an operation to start combustion operation is performed while ventilation is still in progress inside the outer casing 19 and before ventilation is complete. In this case, the start of combustion operation is kept in standby mode (S4: NO, S8: YES, S9). This prevents combustion operation from being started inappropriately while ventilation is still in progress inside the outer casing 19. Subsequently, when the ventilation volume inside the outer casing 19 reaches a predetermined volume, the ventilation inside the outer casing 19 is terminated and combustion operation is started (S10: YES, S11). With this operation control, although there is a delay in the start of combustion operation, the ventilation inside the outer casing 19 is properly terminated and combustion is started. This allows for accurate hot water supply operation by starting combustion while preventing ignition.

[0037] In the combustion device C (hot water device WH) of this embodiment, a sensor for detecting fuel gas leaks and a dedicated fan for ventilating the outer casing 19 are not used. Therefore, it is possible to appropriately simplify the overall configuration of the device and reduce manufacturing costs. In addition, ventilation of the outer casing 19 by driving the fan 1 has the advantage of preventing fuel gas from accumulating in the combustion chamber 29 and exhaust passage 28.

[0038] In the combustion device C (hot water device WH), in addition to or instead of the operation control described above, it is also possible to configure the device to perform the operation control shown in Figures 3 and 4 below.

[0039] The operation control shown in Figure 3 is such that during non-combustion operation, ventilation inside the outer casing 19 is performed intermittently at predetermined time intervals Tc by driving fan 1 (S21:YES, S23). During combustion operation, ventilation inside the outer casing 19 is kept in standby mode (S21:NO, S22). This type of operation control prevents a large accumulation of fuel gas inside the outer casing 19 if a fuel gas leak occurs within it. Therefore, it reduces the likelihood of combustion starting when a large amount of fuel gas has accumulated inside the outer casing 19, thereby suppressing explosive ignition and enhancing safety. The predetermined time Tc does not have to be constant; for example, it is possible to set shorter times during periods of high combustion operation frequency (such as within a few hours from evening) and longer times during other periods. Preferably, the predetermined time Tc can also be changed as appropriate by operating the control unit 51. Although omitted in Figure 3, steps S23 onwards can be similar to the operations from S4 onwards in Figure 2. This also applies to steps S32 onwards in Figure 4, which will be discussed next.

[0040] In the operation control shown in Figure 4, the control unit 5 has a scheduling function, and a user can input and set the scheduled start time for combustion operation of the combustion device C to the control unit 5 by operating the operation unit 51. In response, the control unit 5 almost constantly determines at predetermined short intervals whether the scheduled start time for combustion operation set in this way will arrive within a predetermined time Td from the present time (S31). If this determination concludes that the scheduled start time for combustion operation will arrive within the predetermined time Td, ventilation inside the outer case 19 by driving the fan 1 is started at that time (S31: YES, S32). The predetermined time Td may be the same as the predetermined time Ta shown in Figure 2, but it may also be a different time. With this type of operation control, ventilation inside the outer casing 19 can be performed a suitable amount of time before the scheduled start of combustion operation of the combustion device C. As a result, at the scheduled start of combustion operation, there will be no fuel gas leaking out and accumulating inside the outer casing 19, thus preventing explosive ignition.

[0041] The present invention is not limited to the embodiments described above. The specific configuration of each part of the combustion apparatus according to the present invention can be modified in various ways within the scope intended by the present invention.

[0042] In the above-described embodiment, the combustion device is of the all-primary air combustion type, but the present invention is not limited thereto, and a combustion device without a premixing device can also be used. In addition, in the combustion device C shown in Figure 1, the fan 1 can be positioned downstream of the premixing device 3. The specific type of fan is irrelevant. The present invention is suitable for use with hydrogen or hydrogen-containing gases as fuel gases, but as described above, it is not limited thereto. The combustion device according to the present invention is not limited to hot water supply systems, but can also be used as a combustion device for other purposes such as heating or incineration. Furthermore, it is not limited to types that direct combustion gas downwards. Alternatively, it can be designed to direct the combustion gases upwards, for example. [Explanation of symbols]

[0043] C Combustion device Ca combustion device main body 1 fan 2 Burner section 28 Exhaust passage 28A Additional exhaust passage 29 Combustion chamber 19 Outer case 5. Control Unit (Control Means) 51. Operation Unit (Data Input Means)

Claims

1. The outer case and A combustion device main body is provided, which is located inside the outer casing and includes a combustion chamber equipped with a burner for burning fuel gas supplied to the outer casing from the outside, and an exhaust passage that allows exhaust gas from the combustion chamber to be discharged to the outside of the outer casing. A fan capable of supplying air from inside the outer casing to the combustion chamber and the exhaust passage, This combustion device is equipped with a control means that learns from the combustion operation history of this combustion device and can predict the timing of future combustion operation commencements. A combustion device characterized in that, when the predicted time for the start of combustion operation of the combustion device by this control means arrives within a predetermined time from the present, the fan is driven while the burner section remains in a non-driven combustion state, thereby ventilating the inside of the outer casing.

2. The outer case and A combustion device main body is provided, which is located inside the outer casing and includes a combustion chamber equipped with a burner for burning fuel gas supplied to the outer casing from the outside, and an exhaust passage that allows exhaust gas from the combustion chamber to be discharged to the outside of the outer casing. A fan capable of supplying air from inside the outer casing to the combustion chamber and the exhaust passage, A combustion device characterized by comprising control means for intermittently performing, at predetermined time intervals, the operation of driving the fan while the burner section remains in a non-driven combustion state, thereby ventilating the outer casing.

3. The outer case and A combustion device main body is provided, which is located inside the outer casing and includes a combustion chamber equipped with a burner for burning fuel gas supplied to the outer casing from the outside, and an exhaust passage that allows exhaust gas from the combustion chamber to be discharged to the outside of the outer casing. A fan capable of supplying air from inside the outer casing to the combustion chamber and the exhaust passage, This combustion device is equipped with a control unit that allows input and setting of data regarding the planned start date of future combustion operations. A combustion device characterized in that, when the scheduled start time of combustion operation set in the control means arrives within a predetermined time from the present, the fan is driven while the burner remains in a non-driven combustion state, thereby ventilating the inside of the outer casing.

4. A combustion apparatus according to any one of claims 1 to 3, A combustion device in which ventilation within the outer casing is performed such that the amount of ventilation is equal to or greater than the volume of the outer casing.

5. A combustion apparatus according to any one of claims 1 to 3, The system further includes an additional exhaust passage located outside the outer casing, which is in communication with the aforementioned exhaust passage. A combustion device in which ventilation within the outer casing is performed such that the amount of ventilation is greater than or equal to the sum of the volume of the outer casing and the volume of the additional exhaust passage.

6. A combustion apparatus according to any one of claims 1 to 3, The control means further includes a data input means that can input and set data related to ventilation volume. A combustion device configured such that when ventilation is performed inside the outer casing, the ventilation is performed by an amount corresponding to the ventilation amount data input to the control means.

7. A combustion apparatus according to any one of claims 1 to 3, A combustion apparatus in which hydrogen or a hydrogen-containing gas is used as the fuel gas.

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