Combustion device

Abstract

This design aims to prevent the combustion fan motor in a combustion device from overheating due to excessive current, while ensuring user convenience and comfort. [Solution] Combustion gas is supplied to the burner by driving a combustion fan located inside the enclosure. When a limiting condition based on the current flowing through the combustion fan motor is met, a capacity limiting process is executed to limit the capacity of the combustion fan. In addition, a temperature sensor detects the relevant temperature (outside temperature) that affects the internal temperature of the enclosure. Then, as the relevant temperature increases, adjustments are made to reduce the difficulty of meeting the limiting condition. In such a combustion device, the temperature of the combustion fan motor depends not only on the current flowing through it but also on the internal temperature of the enclosure, and the internal temperature of the enclosure is affected by the relevant temperature. Therefore, by adjusting the device so that the limiting condition is more easily met as the relevant temperature increases, it is possible to suppress the motor from becoming too hot while omitting unnecessary capacity limiting processing and ensuring user convenience and comfort.

Description

Technical Field

[0001] The present invention relates to a combustion device that supplies combustion gas to a burner by driving a combustion fan disposed in a housing and heats a flowing liquid by combustion in the burner.

Background Art

[0002] Combustion devices that perform combustion with a built-in burner are widely used as heat sources for heaters, water heaters, etc. to heat a flowing liquid (such as water or heat medium). Also, in combustion devices, it is known to supply combustion gas (air, or a mixed gas of fuel gas and air) to the burner by driving a combustion fan disposed in the housing.

[0003] In such combustion devices, an excessive current may flow through the motor of the combustion fan, causing the motor to become hot and damaged. Therefore, it has been proposed to suppress the temperature rise of the motor by limiting the capacity (rotation speed, or maximum combustion capacity as a combustion device) of the combustion fan when the value of the current flowing through the motor of the combustion fan reaches the upper limit value (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in a combustion device that limits the capacity of the combustion fan based on the current flowing through the motor of the combustion fan as described above, the temperature of the motor does not only depend on the flowing current, and there may be a case where the motor does not become hot (capacity limitation is not necessary) even when the value of the current reaches the upper limit value. Therefore, there is a problem that the convenience and comfort of the user of the combustion device are impaired due to unnecessary capacity limitation.

[0006] This invention addresses the aforementioned problems of the conventional technology and aims to provide a technology that can ensure user convenience and comfort while suppressing the overheating of the combustion fan motor in a combustion device due to excessive current. [Means for solving the problem]

[0007] To solve the above-mentioned problems, the combustion apparatus of the present invention employs the following configuration: <First aspect> In a combustion device that supplies combustion gas to a burner by driving a combustion fan located inside the enclosure, and heats a flowing liquid by combustion in the burner, When a limiting condition based on the current flowing through the motor of the combustion fan is met, a capacity limiting means is provided to perform a capacity limiting process to limit the capacity of the combustion fan. A temperature sensor that detects relevant temperatures that affect the internal temperature of the housing, An adjustment means that reduces the difficulty of satisfying the limiting condition as the relevant temperature detected by the temperature sensor increases, It is characterized by having the following features.

[0008] In this first embodiment of combustion equipment, the temperature of the combustion fan motor depends not only on the current flowing through the motor but also on the temperature inside the enclosure where the combustion fan is located, and the internal temperature of the enclosure is affected by the related temperature. Therefore, by adjusting the limiting conditions based on the current flowing through the motor so that they are more likely to be met as the related temperature increases, it becomes possible to suppress the motor from overheating due to excessive current by performing capacity limiting processing, while omitting unnecessary capacity limiting processing and ensuring user convenience and comfort.

[0009] <Second aspect> In the combustion apparatus of the first embodiment, The temperature sensor is an ambient temperature sensor that detects the ambient temperature of the environment in which the housing is installed, as the related temperature. It is characterized by the following:

[0010] In this second type of combustion device, for example, if the ambient temperature is high, the internal temperature of the enclosure tends to rise as well, and the motor temperature is likely to rise. Therefore, by making it easier to satisfy the limiting conditions (execution of capacity limiting processing), it is possible to suppress the motor from becoming overheated. On the other hand, if the ambient temperature is low, the internal temperature of the enclosure is less likely to rise, and the motor is less likely to become overheated. Therefore, by making it difficult to satisfy the limiting conditions, it is possible to omit unnecessary capacity limiting processing and ensure the convenience and comfort of the user. Furthermore, since combustion devices that heat a flowing liquid by combustion in a burner generally have ambient temperature sensors to prevent the liquid from freezing, this can be easily implemented by reusing existing ambient temperature sensors.

[0011] <Third aspect> In a combustion apparatus according to the first or second embodiment, A circulation circuit through which the aforementioned liquid circulates, A circulation pump that sends the liquid in the circulation circuit in a predetermined direction, A heat exchanger is provided in the circulation circuit and heats the liquid by heat exchange with the combustion exhaust generated by combustion in the burner. Equipped with, The temperature sensors include a supply temperature sensor that detects the temperature of the liquid flowing out of the heat exchanger as the associated temperature, and a return temperature sensor that detects the temperature of the liquid flowing into the heat exchanger as the associated temperature. It is characterized by the following:

[0012] In this third type of combustion device, while the liquid circulating in the circulation circuit is being heated, the temperature of the liquid flowing out of the heat exchanger (supply temperature) and the temperature of the liquid flowing into the heat exchanger (return temperature) are basically high, and the internal temperature of the enclosure tends to rise as well. Conversely, if both the supply temperature and the return temperature are low, it can be assumed that the internal temperature of the enclosure is low. Therefore, by using the supply temperature and return temperature as the relevant temperatures and adjusting the difficulty of satisfying the limiting conditions, it is possible to ensure user convenience and comfort while suppressing the combustion fan motor from becoming overheated. Furthermore, since combustion devices that heat circulating liquid with a heat exchanger generally have supply temperature sensors and return temperature sensors installed to control the combustion of the burner, this can be easily implemented by reusing existing supply temperature sensors and return temperature sensors.

[0013] <Fourth aspect> In any one of the first to third embodiments of the combustion apparatus, The temperature sensor is an air supply temperature sensor that detects the temperature of the air that has flowed into the housing from the outside as the associated temperature. It is characterized by the following:

[0014] In this fourth type of combustion device, if the temperature of the air flowing into the enclosure from the outside (supply air temperature) is low, it can be expected to have the effect of lowering the internal temperature of the enclosure. However, if the supply air temperature is high, it cannot be expected to have much effect in lowering the internal temperature of the enclosure. Therefore, by using the supply air temperature as the relevant temperature and adjusting the difficulty of satisfying the limiting conditions, it is possible to ensure user convenience and comfort while suppressing the combustion fan motor from becoming overheated.

[0015] <Fifth aspect> In any one of the first to fourth embodiments of the combustion apparatus, The capacity limiting means executes the capacity limiting process when the value of the current flowing to the motor of the combustion fan reaches an upper limit, with the limiting condition being: The aforementioned adjusting means is When the related temperature is less than a predetermined threshold temperature, it invalidates that the value of the current flowing through the motor of the combustion fan has reached the upper limit value, whereas when the related temperature is greater than or equal to the threshold temperature, it validates that the value of the current flowing through the motor of the combustion fan has reached the upper limit value which is characterized by.

[0016] In such a combustion device of the fifth aspect, even if the value of the current flowing through the motor of the combustion fan reaches the upper limit value, if the related temperature is low, by invalidating it, the difficulty level of the establishment of the limiting condition is increased (made impossible to establish), whereas if the related temperature is high, by validating it, the difficulty level of the establishment of the limiting condition can be relatively lowered.

[0017] <Sixth Aspect> In any one of the combustion devices of the first aspect to the fourth aspect, the capacity limiting means executes the capacity limiting process with the fact that the value of the current flowing through the motor of the combustion fan has reached the upper limit value as the limiting condition, the adjustment means decreases the upper limit value as the related temperature increases which is characterized by.

[0018] In such a combustion device of the sixth aspect, if the related temperature is low, by increasing the upper limit value, it becomes difficult for the value of the current flowing through the motor of the combustion fan (hereinafter referred to as the fan current value) to reach the upper limit value, and the establishment of the limiting condition can be made difficult. And as the related temperature increases, if the upper limit value is decreased, the fan current value becomes easier to reach the upper limit value, so the difficulty level of the establishment of the limiting condition can be lowered.

Brief Description of the Drawings

[0019] [Figure 1] It is an explanatory diagram illustrating the configuration of the heating and hot water supply device 1 as an application example of the combustion device. [Figure 2] It is a flowchart of the fan control process of the present embodiment executed by the controller 40 for controlling the combustion fan 5. [Figure 3] This is a flowchart of the fan control process of the first modified example performed by the controller 40. [Figure 4] This is a flowchart of the fan control process for a second modified example performed by the controller 40. [Figure 5] This is a flowchart of the fan control process of the third modified example performed by the controller 40. [Modes for carrying out the invention]

[0020] Figure 1 is an explanatory diagram illustrating the configuration of a heating and hot water supply system 1 as an example of the application of a combustion device. As shown in the figure, the heating and hot water supply system 1 of this embodiment is equipped with a combustion unit 4, which has a burner 3 built inside a housing 2 that burns a mixture of fuel gas and combustion air. A combustion fan 5 is connected to the combustion unit 4 and is equipped with a motor 5a for rotating the combustion fan 5. By energizing the motor 5a and rotating the combustion fan 5, the mixture gas is sent to the combustion unit 4 and supplied to the burner 3. In this embodiment, the housing 2 corresponds to the "enclosure" of the present invention. Also, the mixture gas in this embodiment corresponds to the "combustion gas" of the present invention.

[0021] The intake side of the combustion fan 5 is provided with a confluence section 6 that merges an air supply passage 7, which supplies combustion air, and a gas supply passage 8, which supplies fuel gas. The gas supply passage 8 is equipped with an on / off valve 9 for opening and closing the gas supply passage 8, and a zero governor 10 for reducing the pressure of the fuel gas pumped from the upstream side to atmospheric pressure. The confluence section 6 has a built-in control valve (not shown) that makes it possible to adjust the ratio of combustion air and fuel gas flowing into the combustion fan 5. When the motor 5a is energized and the combustion fan 5 is rotated, the air in the housing 2 and the fuel gas downstream of the zero governor 10 in the gas supply passage 8 are drawn into the combustion fan 5 via the air supply passage 7 in the ratio adjusted by the confluence section 6, and the mixed gas is sent to the combustion unit 4.

[0022] In the combustion unit 4, the mixed gas is burned in the built-in burner 3. In the illustrated example, as the mixed gas is ejected downward from the burner 3, a flame is formed downwards, and the combustion exhaust is sent downwards. The motor 5a and on-off valve 9 of the combustion fan 5 are electrically connected to a controller 40 that controls the overall operation of the heating and hot water supply system 1. The controller 40 controls the opening and closing of the on-off valve 9 and controls the amount of combustion in the burner 3 by changing the rotation speed of the combustion fan 5 by supplying power to the motor 5a according to the required amount of heat (hereinafter referred to as the required heat amount).

[0023] Furthermore, the combustion unit 4 is equipped with a spark plug 11 that generates a spark for the burner 3 by discharging a high voltage, a flame rod 12 that detects the flame (ignition) of the burner 3, and a check valve 13 that prevents backflow from the combustion unit 4 to the combustion fan 5. The spark plug 11 and the flame rod 12 are electrically connected to the controller 40.

[0024] A first heat exchanger 15 is provided below the burner 3, and a second heat exchanger 16 is provided below the first heat exchanger 15. The combustion exhaust generated by the combustion in the burner 3 is sent downward and passes through the first heat exchanger 15 and the second heat exchanger 16 in sequence. At this time, the first heat exchanger 15 recovers sensible heat from the combustion exhaust, and the second heat exchanger 16 recovers latent heat from the combustion exhaust. In this embodiment, the first heat exchanger 15 and the second heat exchanger 16 correspond to the "heat exchanger" of the present invention.

[0025] The combustion exhaust that has passed through the first heat exchanger 15 and the second heat exchanger 16 is discharged through the exhaust duct 17 and out of an exhaust port 18 protruding from the top of the housing 2. Near the exhaust port 18 in the exhaust duct 17, an exhaust temperature sensor 17a is provided to detect the temperature of the discharged combustion exhaust (hereinafter referred to as exhaust temperature). In the illustrated example, an air intake port 19 is provided at the top of the housing 2 and is connected to an air intake passage 19a formed in the upper part of the housing 2. Air taken into the housing 2 from the air intake port 19 through the air intake passage 19a is supplied to the confluence section 6 through the air supply path 7, and the downstream end of the air intake passage 19a shown in Figure 1 is located near the combustion fan 5. Near the downstream end of this air intake passage 19a, an air intake temperature sensor 2a is provided to detect the temperature of the air that has flowed in from the outside through the air intake port 19 (hereinafter referred to as air intake temperature). Furthermore, an outside air temperature sensor 2b is provided at the bottom of the housing 2 to detect the outside air temperature of the environment in which the housing 2 is installed. Furthermore, the exhaust temperature sensor 17a, the intake air temperature sensor 2a, and the outside air temperature sensor 2b are electrically connected to the controller 40.

[0026] The first heat exchanger 15 is connected upstream to the downstream side of the second heat exchanger 16. The downstream side of the first heat exchanger 15 is connected to the upstream side of the panel radiator 20, which serves as a heating terminal, via a supply passage 21, and the upstream side of the second heat exchanger 16 is connected to the downstream side of the panel radiator 20 via a return passage 22. The return passage 22 is equipped with a circulation pump 23 that sends the heat transfer medium toward the second heat exchanger 16, and a return temperature sensor 24 that detects the temperature of the heat transfer medium flowing into the second heat exchanger 16 (hereinafter referred to as the return temperature). The circulation pump 23 and the return temperature sensor 24 are electrically connected to the controller 40.

[0027] The heat transfer medium sent to the second heat exchanger 16 by the operation of the circulation pump 23 is preheated in the second heat exchanger 16 by the latent heat recovered from the combustion exhaust of the burner 3, and then sent to the first heat exchanger 15. In the first heat exchanger 15, the heat transfer medium is heated by the sensible heat recovered from the combustion exhaust of the burner 3, and the high-temperature heat transfer medium is supplied to the panel radiator 20 through the supply passage 21. A supply temperature sensor 25 is provided in the supply passage 21 connected downstream of the first heat exchanger 15 to detect the temperature of the heat transfer medium flowing out of the first heat exchanger 15 (hereinafter referred to as the supply temperature), and the supply temperature sensor 25 is electrically connected to the controller 40. The controller 40 determines the required heat quantity (the amount of heating needed) based on the target temperature of the heat transfer medium in heating operation, the temperature detected by the supply temperature sensor 25, and the temperature detected by the return temperature sensor 24, and controls the combustion of the burner 3.

[0028] The panel radiator 20 is equipped with a pipe 20a that meanders within a metal panel and an on-off valve 20b that opens and closes the pipe 20a. When the on-off valve 20b is opened, the heat transfer medium passes through the pipe 20a and radiates heat, warming the surrounding area. The heat transfer medium that has passed through the panel radiator 20 returns to the circulation pump 23 via the return passage 22 and is sent again to the second heat exchanger 16 for circulation. The circulation pump 23 in this embodiment is designed to deliver the heat transfer medium while maintaining a constant rotational speed. In this embodiment of the heating and hot water supply system 1, hot water is used as the heat transfer medium, but the heat transfer medium is not limited to hot water, and antifreeze such as ethylene glycol or silicone oil may also be used. Furthermore, the heat transfer medium in this embodiment corresponds to the "liquid" of the present invention.

[0029] Furthermore, a branch passage 27, which branches off from the supply passage 21 downstream of the supply temperature sensor 25, is connected to the return passage 22 upstream of the circulation pump 23, and a hot water heat exchanger 28 is provided in this branch passage 27. In addition, a three-way valve 29 is provided at the connection point between the branch passage 27 and the return passage 22, and the three-way valve 29 is electrically connected to the controller 40. This three-way valve 29 makes it possible to switch whether the heat transfer medium flowing out of the first heat exchanger 15 is circulated through the route passing through the panel radiator 20 (heating terminal) (hereinafter referred to as the external circulation circuit) or through the route passing through the hot water heat exchanger 28 (hereinafter referred to as the internal circulation circuit). In this embodiment, both the external circulation circuit and the internal circulation circuit correspond to the "circulation circuit" of the present invention. Hereafter, when there is no need to particularly distinguish between the external circulation circuit and the internal circulation circuit, they may simply be referred to as the "circulation circuit".

[0030] The hot water heat exchanger 28 is a liquid-liquid heat exchanger, and is connected to a water supply passage 30 and a hot water outlet passage 31. Tap water supplied to the hot water heat exchanger 28 through the water supply passage 30 is heated in the hot water heat exchanger 28 by heat exchange with a heat transfer medium, and flows out as hot water through the hot water outlet passage 31. The water supply passage 30 is equipped with a water flow sensor 32 for detecting the flow rate of tap water flowing into the heating and hot water supply device 1, a water flow servo 33 for adjusting the flow rate of tap water, and a water supply temperature sensor 34 for detecting the temperature of tap water. The hot water outlet passage 31 is equipped with a heat exchange outlet hot water temperature sensor 35 for detecting the temperature of the hot water immediately after it flows out of the hot water heat exchanger 28. These water flow sensors 32, water flow servo 33, water supply temperature sensor 34, and heat exchange outlet hot water temperature sensor 35 are electrically connected to the controller 40.

[0031] Furthermore, in the heating and hot water supply system 1 of this embodiment, the downstream side of the water supply temperature sensor 34 in the water supply passage 30 and the downstream side of the heat exchanger hot water temperature sensor 35 in the hot water outlet passage 31 are connected by a bypass passage 36. Some of the tap water flowing into the heating and hot water supply system 1 can pass through the bypass passage 36 without being supplied to the hot water heat exchanger 28, while the remainder is supplied to the hot water heat exchanger 28. The hot water heated in the hot water heat exchanger 28 is then mixed with the tap water that has passed through the bypass passage 36 and flows out of the heating and hot water supply system 1. A bypass servo 37 is provided at the connection point between the bypass passage 36 and the hot water outlet passage 31, and the bypass servo 37 is electrically connected to the controller 40. The mixing ratio of the hot water heated in the hot water heat exchanger 28 and the tap water that has passed through the bypass passage 36 can be changed by the bypass servo 37.

[0032] Downstream of the bypass servo 37 in the hot water outlet passage 31, a hot water outlet temperature sensor 38 is provided to detect the temperature of the hot water flowing out from the heating and hot water supply device 1, and the hot water outlet temperature sensor 38 is electrically connected to the controller 40. As described above, if a portion of the tap water from the water supply passage 30 flows through the bypass passage 36 and joins the hot water outlet passage 31 without passing through the hot water heat exchanger 28, the temperature detected by the hot water outlet temperature sensor 38 will naturally be lower than the temperature detected by the heat exchanger outlet temperature sensor 35, and the temperature fluctuation of the hot water flowing out from the heating and hot water supply device 1 can be suppressed by adjusting the mixing ratio with the bypass servo 37. In addition, the controller 40 determines the required heat quantity (the amount of heating needed) based on the target temperature of the heat medium during hot water supply operation, the temperature detected by the supply temperature sensor 25, the temperature detected by the return temperature sensor 24, the temperature detected by the hot water outlet temperature sensor 38, the temperature detected by the water supply temperature sensor 34, the flow rate detected by the water volume sensor 32, and the mixing ratio of the bypass servo 37, and controls the combustion of the burner 3.

[0033] Furthermore, the controller 40 is electrically connected to a hot water remote control 41 and a heating remote control 42. By operating the hot water remote control 41, the user can switch the hot water operation, which circulates the heat medium in the internal circulation circuit, between ON and OFF states, and set the hot water temperature. Similarly, by operating the heating remote control 42, the user can instruct the start and stop of the heating operation, which circulates the heat medium in the external circulation circuit, and set the heating temperature. The controller 40 then changes the target temperature of the heat medium in each operating state according to the hot water temperature set by the hot water remote control 41 and the heating temperature set by the heating remote control 42.

[0034] In the heating and hot water supply system 1 described above, the motor 5a is energized to rotate the combustion fan 5, supplying a mixture of fuel gas and combustion air to the burner 3 of the combustion unit 4. As the load on the motor 5a of the combustion fan 5 increases, the current flowing to the motor 5a increases, and if an excessive current flows, the motor 5a may overheat and be damaged. For this reason, it has been conventional practice to set an upper limit on the current flowing to the motor 5a of the combustion fan 5 in advance, and to limit the capacity of the combustion fan 5 when the upper limit is reached, thereby suppressing the temperature rise of the motor 5a. However, the temperature of the motor 5a does not depend solely on the current flowing through it, and there are cases where the motor 5a does not overheat even when the current reaches the upper limit (no capacity limit is necessary), so unnecessary capacity limiting impairs the convenience and comfort of the user. Therefore, in the heating and hot water supply system 1 of this embodiment, in order to suppress the motor 5a of the combustion fan 5 from overheating due to excessive current while ensuring the convenience and comfort of the user, the controller 40 controls the combustion fan 5 as follows.

[0035] Figure 2 is a flowchart of the fan control process performed by the controller 40 in this embodiment to control the combustion fan 5. This fan control process is performed to activate (rotate) the combustion fan 5 when either the heating operation or the hot water supply operation starts, and continues until the heating operation or hot water supply operation ends. As shown in the figure, when the fan control process starts, first the rotation speed of the combustion fan 5 is set according to the required heat amount (STEP 1).

[0036] As mentioned above, the controller 40 determines the required heat quantity based on the target temperature of the heat medium, the supply temperature detected by the supply temperature sensor 25, and the return temperature detected by the return temperature sensor 24 when in heating operation. When in hot water operation, it determines the required heat quantity based on the target temperature of the heat medium, the supply temperature, and the return temperature, as well as the temperature detected by the hot water temperature sensor 38, the temperature detected by the water supply temperature sensor 34, the flow rate detected by the water flow rate sensor 32, and the mixing ratio of the bypass servo 37. When the required heat quantity increases, the controller 40 increases the rotation speed of the combustion fan 5 to increase the amount of mixed gas supplied to the burner 3 (amount of combustion in the burner 3), and when the required heat quantity decreases, it decreases the rotation speed of the combustion fan 5 to decrease the amount of mixed gas supplied to the burner 3. If there is no change in the required heat quantity, the controller 40 maintains the current rotation speed of the combustion fan 5. In addition, even when combustion in the burner 3 is stopped (the on-off valve 9 is closed), the combustion fan 5 may be rotated for pre-purging before ignition or post-purging after extinguishing.

[0037] After setting the rotation speed of the combustion fan 5, it is then determined whether the value of the current flowing through the motor 5a of the combustion fan 5 (hereinafter referred to as the fan current value) has exceeded a predetermined upper limit (STEP 2). In the heating and hot water supply system 1 of this embodiment, as a general rule, when the fan current value reaches a predetermined upper limit, the capacity of the combustion fan 5 is limited as described below in order to prevent the motor 5a of the combustion fan 5 from becoming overheated.

[0038] If the fan current value is not above the upper limit (STEP2: no), the next step is to determine whether the capacity of the combustion fan 5 is already limited (STEP3). If the capacity of the combustion fan 5 is already limited (STEP3: yes), the capacity limit of the combustion fan 5 is released based on the fact that the fan current value has not reached the upper limit (STEP4). On the other hand, if the capacity of the combustion fan 5 is not limited (STEP3: no), the process in STEP4 is omitted. With the capacity of the combustion fan 5 not limited, the process returns to STEP1, and the rotation speed of the combustion fan 5 is set again according to the required heat amount (STEP1).

[0039] In this embodiment, the fan control process immediately releases the capacity limit if the fan current value falls below the upper limit while the capacity of the combustion fan 5 is being limited. However, even if the fan current value falls below the upper limit, the capacity limit may be maintained until it falls below a value obtained by subtracting a certain number from the upper limit (hereinafter referred to as the subtracted value), and then the capacity limit may be released once it falls below the subtracted value. By setting a certain difference between the threshold value that activates the capacity limit of the combustion fan 5 (upper limit) and the threshold value that releases it (subtracted value), it is possible to suppress the situation in which the capacity limit is activated and released repeatedly in a short period of time as the fan current value remains near the upper limit.

[0040] In contrast, if the fan current value exceeds the upper limit (STEP 2: yes), the upper limit reached flag is set to ON (STEP 5). This upper limit reached flag indicates that the fan current value has reached the upper limit, and a storage area for this flag is reserved in the memory unit (not shown) of the controller 40.

[0041] When the upper limit reached flag is set to ON, the next step is to determine whether the outside air temperature is above a predetermined outside air threshold temperature (STEP 6). As mentioned above, the heating and hot water supply device 1 of this embodiment is equipped with an outside air temperature sensor 2b, and based on the decrease in outside air temperature detected by the outside air temperature sensor 2b, it performs freeze prevention operations (such as operating the circulation pump 23) to prevent the heat transfer medium in the circulation circuit from freezing. The internal temperature of the housing 2 is easily affected by the outside air temperature, and if the outside air temperature is high, the internal temperature of the housing 2 tends to be high, and if the outside air temperature is low, the internal temperature of the housing 2 tends to be low (less likely to rise).

[0042] In this embodiment, the ambient temperature threshold is set to, for example, 0 degrees. If the ambient temperature is below the ambient temperature threshold (STEP 6: no), the upper limit flag, which was set to ON in STEP 5, is set to OFF (STEP 7). On the other hand, if the ambient temperature is above the ambient temperature threshold (STEP 6: yes), the process in STEP 7 is omitted, and the upper limit flag is not set to OFF.

[0043] Regardless of whether the setting of the upper limit flag has been changed based on the ambient temperature, the next step is to determine whether the upper limit flag is set to ON (STEP 8). If the upper limit flag is set to ON (STEP 8: yes), a capacity limiting process is executed to limit the capacity of the combustion fan 5 (STEP 9). In the capacity limiting process of this embodiment, the maximum combustion amount of the burner 3 in the combustion unit 4 is reduced by a predetermined amount, so that even if the required heat amount increases, it cannot exceed the maximum combustion amount of the burner 3, and as a result the rotation speed of the combustion fan 5 is limited to a rotation speed corresponding to the maximum combustion amount of the burner 3. The capacity limiting process is not limited to this, and the capacity of the combustion fan 5 may also be directly limited by reducing the maximum rotation speed of the combustion fan 5. Furthermore, the controller 40 of this embodiment that executes the capacity limiting process has a function equivalent to the "capacity limiting means" of the present invention.

[0044] After performing the capacity limiting process in this manner, if the upper limit reached flag is set to OFF (STEP10), the process returns to STEP1, and with the capacity of the combustion fan 5 limited, the rotation speed of the combustion fan 5 is set again according to the required heat amount (STEP1). On the other hand, if the upper limit reached flag is not set to ON in the judgment of STEP8 (STEP8: no), the processes of STEP9 and STEP10 are omitted, and the process returns to STEP1, and with the capacity of the combustion fan 5 not limited, the rotation speed of the combustion fan 5 is set again according to the required heat amount (STEP1).

[0045] As explained above, in the heating and hot water supply device 1 of this embodiment, even if the fan current value reaches a predetermined upper limit and the upper limit flag is turned ON, if the outside air temperature is below the outside air threshold temperature, the upper limit flag is turned OFF and disabled, thereby increasing the difficulty of fulfilling the conditions for executing the capacity limiting process (hereinafter referred to as the limiting conditions) (making them impossible to fulfill). On the other hand, if the outside air temperature is above the outside air threshold temperature, the upper limit flag is kept ON and enabled, thereby relatively lowering the difficulty of fulfilling the limiting conditions. The controller 40 of this embodiment, which lowers the difficulty of fulfilling the limiting conditions as the outside air temperature rises, has a function equivalent to the "adjustment means" of the present invention.

[0046] The temperature of the motor 5a of the combustion fan 5 depends not only on the current flowing through the motor 5a, but also on the temperature inside the housing 2 in which the combustion fan 5 is located, and the internal temperature of the housing 2 is easily affected by the ambient temperature. For example, if the ambient temperature is high, the internal temperature of the housing 2 tends to rise as well, and the temperature of the motor 5a tends to rise, so it is possible to suppress the motor 5a from becoming too hot by making it easier for the limiting condition to be met (execution of capacity limiting processing). On the other hand, if the ambient temperature is low, the internal temperature of the housing 2 does not rise easily, and the motor 5a does not tend to become too hot, so it is possible to make it difficult for the limiting condition to be met, thereby omitting unnecessary capacity limiting processing and ensuring the convenience and comfort of the user. Furthermore, since heating and hot water supply systems 1 generally have an ambient temperature sensor 2b to prevent freezing of the heat transfer medium in the circulation circuit, it can be easily implemented by reusing the existing ambient temperature sensor 2b.

[0047] The heating and hot water supply device 1 of the above-described embodiment also has the following modifications. Below, the modifications will be described focusing on the differences from the above-described embodiment. In the description of the modifications, components that are the same as those in the above-described embodiment will be denoted by the same reference numerals and their description will be omitted.

[0048] Figure 3 is a flowchart of the fan control process of the first modified example executed by the controller 40. Since the fan control process of the first modified example has many processes in common with the fan control process of the embodiment described above, a detailed explanation of the common processes will be omitted. When the fan control process of the first modified example is started, first the rotation speed of the combustion fan 5 is set according to the required amount of heat (STEP 21), and then it is determined whether the value of the current flowing to the motor 5a of the combustion fan 5 (fan current value) has exceeded a predetermined upper limit (STEP 22).

[0049] If the fan current value is not above the upper limit (STEP22: no), then it is determined whether the capacity of the combustion fan 5 is currently limited (STEP23). If the capacity of the combustion fan 5 is currently limited (STEP23: yes), the capacity limit for the combustion fan 5 is removed (STEP24). As mentioned above, while the capacity of the combustion fan 5 is limited, the capacity limit may be removed after waiting for the fan current value to fall below a value obtained by subtracting a certain number from the upper limit (subtracted value). On the other hand, if the capacity of the combustion fan 5 is not currently limited (STEP23: no), the process in STEP24 is omitted. With the capacity of the combustion fan 5 not limited, the process returns to STEP21, and the rotation speed of the combustion fan 5 is set again according to the required heat amount (STEP21).

[0050] In response to this, if the fan current value exceeds the upper limit (STEP22: yes), the upper limit reached flag is set to ON (STEP25), and it is determined whether the outside air temperature is above a predetermined outside air threshold temperature (e.g., 0 degrees) (STEP26). If the outside air temperature is below the outside air threshold temperature (STEP26: no), it is then determined whether at least one of the following conditions is met: the supply temperature is above the supply threshold temperature, and the return temperature is above the return threshold temperature (STEP27).

[0051] As mentioned above, the heating and hot water supply system 1 illustrated in Figure 1 is equipped with a supply temperature sensor 25 for detecting the supply temperature and a return temperature sensor 24 for detecting the return temperature, in order to control the combustion of the burner 3 according to the required amount of heat. When the heat transfer medium circulating in the circulation circuit is being heated during either heating or hot water supply operation, the supply temperature and return temperature are basically high, and the internal temperature of the housing 2 also tends to be high. Conversely, if both the supply temperature and return temperature are low, it can be assumed that the internal temperature of the housing 2 is low.

[0052] In the fan control process of the first modified example, the supply threshold temperature is set to, for example, 60 degrees, and the return threshold temperature is set to, for example, 40 degrees. If the supply temperature is less than the supply threshold temperature and the return temperature is less than the return threshold temperature (STEP 27: no), then it is determined whether the supply air temperature is equal to or greater than the supply air threshold temperature (STEP 28).

[0053] As illustrated in Figure 1, the heating and hot water supply system 1 has an air supply temperature sensor 2a mounted near the downstream end of the air supply passage 19a inside the housing 2, as described above. The air supply temperature sensor 2a can detect the temperature of the air flowing in from the outside through the air intake port 19 (air supply temperature). If the air supply temperature is low, the air flowing in from the outside can be expected to lower the internal temperature of the housing 2. However, if the air supply temperature is high, the effect of lowering the internal temperature of the housing 2 is not expected to be significant. In particular, in the example shown in Figure 1, the combustion fan 5 is located at the top of the housing 2, and the downstream end of the air supply passage 19a is located near the combustion fan 5. Therefore, if the air supply temperature is low, the air flowing in from the outside through the air intake port 19 and the air supply passage 19a flows around the motor 5a of the combustion fan 5, and a direct cooling effect on the motor 5a can be obtained.

[0054] In the first modified example, the supply air threshold temperature is set to, for example, 10 degrees. If the supply air temperature is below the supply air threshold temperature (STEP28: no), the upper limit reached flag, which was set to ON in STEP25, is set to OFF (STEP29). On the other hand, in the determination in STEP26, if the outside air temperature is above the outside air threshold temperature (STEP26: yes), the processes in STEP27 to STEP29 are omitted, and the upper limit reached flag is not set to OFF. Also, in the determination in STEP27, if at least one of the following is true (forward temperature is above the forward threshold temperature, and return temperature is above the return threshold temperature), the processes in STEP28 and STEP29 are omitted, and the upper limit reached flag is not set to OFF. Furthermore, in the determination in STEP28, if the supply air temperature is above the supply air threshold temperature (STEP28: yes), the process in STEP29 is omitted, and the upper limit reached flag is not set to OFF.

[0055] In this way, regardless of whether the setting of the upper limit reached flag has been changed based on the outside air temperature, supply and return temperatures, and supply air temperature, it is then determined whether the upper limit reached flag is set to ON or not (STEP30). If the upper limit reached flag is set to ON (STEP30: yes), after executing the capacity limiting process (STEP31), if the upper limit reached flag is set to OFF (STEP32), the process returns to STEP21, and with the capacity of the combustion fan 5 limited, the rotation speed of the combustion fan 5 is set again according to the required heat amount (STEP21). On the other hand, if the upper limit reached flag is not set to ON (STEP30: no), the processes in STEP31 and STEP32 are omitted, and the process returns to STEP21, and with the capacity of the combustion fan 5 not limited, the rotation speed of the combustion fan 5 is set again according to the required heat amount (STEP21).

[0056] As explained above, in the first modified heating and hot water supply device 1, when the fan current value reaches a predetermined upper limit and the upper limit reached flag is turned ON, the device checks the outside air temperature, as well as the supply air temperature, return air temperature, and supply air temperature. If any of these are below the threshold temperature (outside air threshold temperature, supply air threshold temperature, return air threshold temperature, and supply air threshold temperature), the upper limit reached flag is turned OFF and disabled, thereby increasing the difficulty of fulfilling the limit condition (making it impossible to fulfill). On the other hand, if any one of them is above the threshold temperature, the upper limit reached flag is kept ON and enabled, thereby relatively lowering the difficulty of fulfilling the limit condition.

[0057] As mentioned above, when heating the heat transfer medium circulating in the circulation circuit, the supply temperature and return temperature are basically high, and the internal temperature of the housing 2 tends to rise as well. Conversely, if both the supply temperature and return temperature are low, it can be assumed that the internal temperature of the housing 2 is low. By adjusting the difficulty of satisfying the limiting conditions based on the supply temperature and return temperature which affect the internal temperature of the housing 2, it is possible to ensure user convenience and comfort while suppressing the motor 5a of the combustion fan 5 from becoming too hot. Furthermore, since heating and hot water supply systems generally have a supply temperature sensor 25 and a return temperature sensor 24 installed to control the combustion of the burner 3, this can be easily implemented by reusing the existing supply temperature sensor 25 and return temperature sensor 24.

[0058] In addition, if the temperature of the air flowing into the housing 2 from the outside (supply air temperature) is low, it can be expected to have the effect of lowering the internal temperature of the housing 2, whereas if the supply air temperature is high, it cannot be expected to have much effect on lowering the internal temperature of the housing 2. In this way, the supply air temperature affects the internal temperature of the housing 2, so by adjusting the difficulty of satisfying the limiting conditions based on the supply air temperature, it is possible to suppress the motor 5a of the combustion fan 5 from becoming too hot while ensuring the convenience and comfort of the user.

[0059] Furthermore, in the first modified heating and hot water supply device 1, when the fan current value reaches a predetermined upper limit, the device is invalid (limiting condition cannot be met) only if all of the outside air temperature, supply air temperature, return air temperature, and supply air temperature are below the threshold temperature (outside air threshold temperature, supply air threshold temperature, return air threshold temperature, and supply air threshold temperature). If any one of them is above the threshold temperature, the device is valid (limiting condition can be met). This increases the likelihood that the limiting condition will be met and the capacity limiting process will be executed.

[0060] Figure 4 is a flowchart of the fan control process of the second modified example executed by the controller 40. Since the fan control process of the second modified example has many processes in common with the fan control process of the previously described embodiment and the first modified example, a detailed explanation of the common processes will be omitted. When the fan control process of the second modified example is started, first the rotation speed of the combustion fan 5 is set according to the required heat amount (STEP 41), and then it is determined whether the value of the current flowing to the motor 5a of the combustion fan 5 (fan current value) has exceeded a predetermined upper limit (STEP 42).

[0061] If the fan current value is not above the upper limit (STEP42: no), then it is determined whether the capacity of the combustion fan 5 is currently limited (STEP43). If the capacity of the combustion fan 5 is currently limited (STEP43: yes), the capacity limit for the combustion fan 5 is removed (STEP44). As mentioned above, while the capacity of the combustion fan 5 is limited, the capacity limit may be removed after waiting for the fan current value to fall below a value obtained by subtracting a certain number from the upper limit (subtracted value). On the other hand, if the capacity of the combustion fan 5 is not currently limited (STEP43: no), the process in STEP44 is omitted. With the capacity of the combustion fan 5 not limited, the process returns to STEP41, and the rotation speed of the combustion fan 5 is set again according to the required heat amount (STEP41).

[0062] In response to this, if the fan current value exceeds the upper limit (STEP42: yes), the upper limit reached flag is set to ON (STEP45), and it is determined whether the outside temperature is above a predetermined outside threshold temperature (e.g., 0 degrees) (STEP46). If the outside temperature is below the outside threshold temperature (STEP46: no), the upper limit reached flag, which was set to ON in STEP45, is set to OFF (STEP49).

[0063] On the other hand, if the outside air temperature is above the outside air threshold temperature (STEP46: yes), then it is determined whether the outgoing temperature is above the outgoing threshold temperature (e.g., 60 degrees) and the return temperature is above the return threshold temperature (e.g., 40 degrees) (STEP47). If the outgoing temperature is below the outgoing threshold temperature and the return temperature is below the return threshold temperature (STEP47: no), the upper limit reached flag, which was set to ON in STEP45, is set to OFF (STEP49).

[0064] In contrast, if the supply temperature is above the supply threshold temperature and at least one of the return temperature is above the return threshold temperature (STEP47: yes), then it is determined whether the supply air temperature is above the supply air threshold temperature (e.g., 10 degrees) (STEP48). If the supply air temperature is below the supply air threshold temperature (STEP48: no), the upper limit reached flag, which was set to ON in STEP45, is set to OFF (STEP49). On the other hand, if the supply air temperature is above the supply air threshold temperature (STEP48: yes), the process in STEP49 is omitted and the upper limit reached flag is not set to OFF.

[0065] In this way, regardless of whether the setting of the upper limit reached flag has been changed based on the outside air temperature, supply and return temperatures, and supply air temperature, it is then determined whether the upper limit reached flag is set to ON or not (STEP 50). If the upper limit reached flag is set to ON (STEP 50: yes), after executing the capacity limiting process (STEP 51), if the upper limit reached flag is set to OFF (STEP 52), the process returns to STEP 41, and with the capacity of the combustion fan 5 limited, the rotation speed of the combustion fan 5 is set again according to the required heat amount (STEP 41). On the other hand, if the upper limit reached flag is not set to ON (STEP 50: no), the processes of STEP 51 and STEP 52 are omitted, and the process returns to STEP 41, and with the capacity of the combustion fan 5 not limited, the rotation speed of the combustion fan 5 is set again according to the required heat amount (STEP 41).

[0066] As explained above, in the second modified heating and hot water supply device 1, when the fan current value reaches a predetermined upper limit and the upper limit reached flag is turned ON, the system checks the outside air temperature, the supply and return temperatures, and the supply air temperature. If at least one of the following three conditions is not met, the upper limit reached flag is turned OFF and disabled, thereby increasing the difficulty of fulfilling the limit condition (making it impossible to fulfill). On the other hand, if all three conditions are met, the upper limit reached flag is kept ON and enabled, thereby relatively lowering the difficulty of fulfilling the limit condition.

[0067] Thus, when the fan current value reaches a predetermined upper limit, the system is considered effective (the limiting condition can be met) only if all three conditions (a) to (c) are met based on the ambient temperature, supply and return temperatures, and supply air temperature. If even one of (a) to (c) is not met, the system is considered invalid (the limiting condition cannot be met). By keeping the possibility of the limiting condition being met low and delaying its occurrence, it is possible to determine whether or not capacity limiting processing is necessary.

[0068] Figure 5 is a flowchart of the fan control process of the third modified example executed by the controller 40. Since the fan control process of the third modified example shares many processes with the fan control process of the previously described embodiment, a detailed explanation of the common processes will be omitted. When the fan control process of the third modified example is started, first, the rotation speed of the combustion fan 5 is set according to the required heat output (STEP 61).

[0069] After setting the rotation speed of the combustion fan 5, the next step is to determine whether the ambient temperature (temperature detected by the ambient temperature sensor 2b) is above a predetermined first threshold temperature (e.g., 0 degrees) (STEP 62). If the ambient temperature is below the first threshold temperature (STEP 62: no), the upper limit of the fan current value (the value of the current flowing to the motor 5a of the combustion fan 5) is set to "large" (STEP 63). In the third modified example of the heating and hot water supply device 1, the upper limit of the fan current value can be switched between three levels: large, medium, and small, and here the largest "large" is selected.

[0070] In response to this, if the ambient temperature is above the first threshold temperature (STEP62: yes), then it is determined whether the ambient temperature is above the second threshold temperature (e.g., 25 degrees Celsius), which is higher than the first threshold temperature (STEP64). If the ambient temperature is below the second threshold temperature (STEP64: no), the upper limit of the fan current value is set to "medium," which is the second largest of the three levels (STEP65).

[0071] On the other hand, if the ambient temperature is above the second threshold temperature (STEP 64: yes), the upper limit of the fan current value is set to "small," the smallest of the three levels (STEP 66). In this way, by setting the upper limit of the fan current value to large, medium, or small according to the ambient temperature, it is determined whether the fan current value has exceeded the set upper limit (STEP 67). Note that the controller 40 of the third modified example, which switches the upper limit of the fan current value according to the ambient temperature, has a function equivalent to the "adjustment means" of the present invention.

[0072] If the fan current value is not above the set upper limit (STEP67: no), then it is determined whether the capacity of the combustion fan 5 is being limited (STEP68). If the capacity of the combustion fan 5 is being limited (STEP68: yes), the capacity limit of the combustion fan 5 is released based on the fact that the fan current value has not reached the upper limit (STEP69). As mentioned above, while the capacity of the combustion fan 5 is being limited, the capacity limit may be released after waiting for the fan current value to fall below a value obtained by subtracting a certain number from the upper limit (subtracted value). On the other hand, if the capacity of the combustion fan 5 is not being limited (STEP68: no), the process in STEP69 is omitted. With the capacity of the combustion fan 5 thus not being limited, the process returns to STEP61, and the rotation speed of the combustion fan 5 is set again according to the required heat amount (STEP61).

[0073] In response to this, if the fan current value exceeds the set upper limit (STEP67: yes), the capacity limiting process is executed (STEP70), and then the process returns to STEP61, where the rotation speed of the combustion fan 5 is set again according to the required heat amount with the capacity of the combustion fan 5 limited (STEP61).

[0074] As explained above, in the third modified heating and hot water supply device 1, while the capacity limiting process is performed based on the condition that the fan current value reaches the upper limit, the upper limit is reduced as the outside temperature rises. This means that, for example, if the outside temperature is low, below 0 degrees, setting the upper limit to "high" makes it difficult for the fan current value to reach the upper limit, making it difficult for the limiting condition to be met. As a result, unnecessary capacity limiting processing can be omitted, ensuring user convenience and comfort. Furthermore, as the outside temperature rises, switching the upper limit to "medium" or "low" makes it easier for the fan current value to reach the upper limit, thus reducing the difficulty of meeting the limiting condition and preventing the motor 5a from becoming overheated due to the execution of capacity limiting processing.

[0075] Although the heating and hot water supply device 1 (combustion device) of the embodiments and modified examples have been described above, the present invention is not limited to the embodiments and modified examples described above, and can be implemented in various forms without departing from the spirit of the invention.

[0076] For example, in the embodiment described above, an example was explained in which the ambient temperature alone was used as the relevant temperature that affects the internal temperature of the housing 2. However, instead of the ambient temperature, a combination of supply temperature and return temperature may be used as the relevant temperature, or the supply air temperature may be used alone.

[0077] Furthermore, in the third modified example mentioned above, the upper limit of the fan current value can be switched between three levels, and as the ambient temperature rises, the upper limit is gradually reduced by switching between high, medium, and low. However, the switching of the upper limit is not limited to three levels; multiple levels are acceptable. In addition, the switching of the upper limit is not limited to a stepwise manner; the upper limit may be continuously reduced as the ambient temperature rises.

[0078] Furthermore, in the third modified example described above, the ambient temperature was used as the relevant temperature that affects the internal temperature of the housing 2. However, the relevant temperature is not limited to the ambient temperature; the upper limit of the fan current value may be reduced as the supply and return temperatures increase. Alternatively, the upper limit of the fan current value may be reduced as the supply air temperature increases.

[0079] Furthermore, in the embodiments and modifications described above, the ambient temperature, supply and return temperatures, and intake air temperature were explained as examples of relevant temperatures that affect the internal temperature of the housing 2. However, the relevant temperatures are not limited to these, and may also be, for example, the exhaust temperature detected by the exhaust temperature sensor 17a. During combustion in the burner 3, the exhaust temperature is basically high, and the internal temperature of the housing 2 tends to be high as well. Conversely, if the exhaust temperature is low, it can be assumed that the internal temperature of the housing 2 is low.

[0080] Furthermore, in the embodiments described above, a heating and hot water supply system 1 equipped with an external circulation circuit for heating operation and an internal circulation circuit for hot water supply operation was described as an example of the application of the combustion device. However, the application of the combustion device is not limited to the heating and hot water supply system 1, and may also be a heater or water heater equipped with either an external circulation circuit or an internal circulation circuit.

[0081] Furthermore, in the embodiment described above, the combustion fan 5 was rotated to supply a mixture of fuel gas and combustion air as a combustion gas to the burner 3 of the combustion unit 4. However, the combustion fan 5 may be driven to supply only combustion air as a combustion gas to the burner 3, while the fuel gas is supplied directly to the burner 3 through the gas supply passage 8.

[0082] Furthermore, in the embodiments described above, a panel radiator 20 was used as an example of a heating terminal. However, the heating terminal is not limited to a panel radiator 20, as long as it releases heat from the heat transfer medium, it may also be a bathroom heater / dryer, a fan convector, or underfloor heating.

[0083] Furthermore, in the embodiment described above, the water supply passage 30 and the hot water outlet passage 31 are connected by a bypass passage 36, and the mixing ratio of the hot water heated by the hot water heat exchanger 28 and the tap water that passes through the bypass passage 36 can be changed by a bypass servo 37. However, the embodiment is not limited to this, and the bypass passage 36 and the bypass servo 37 may be omitted. In this case, it is not necessary to provide the heat exchanger outlet hot water temperature sensor 35 and the outlet hot water temperature sensor 38 separately, and they may be combined into a single temperature sensor.

[0084] Furthermore, in the embodiment described above, a first heat exchanger 15 and a second heat exchanger 16 are provided, and the circulating heat medium is preheated in the second heat exchanger 16 before being heated in the first heat exchanger 15. However, the embodiment is not limited to this, and the second heat exchanger 16 may be omitted, and the heat medium may be heated by the first heat exchanger 15 alone. [Explanation of Symbols]

[0085] 1...Heating and hot water supply system, 2...Housing, 2a...Intake air temperature sensor, 2b...Outside temperature sensor, 3...Burner, 4...Combustion unit, 5... Combustion fan, 5a... Motor, 6... Junction, 7...Air supply passage, 8...Gas supply passage, 9...On / off valve, 10... Zero governor, 11... Spark plug, 12... Flame rod 13... Check valve, 15... First heat exchanger, 16... Second heat exchanger, 17... Exhaust duct, 17a... Exhaust temperature sensor, 18... Exhaust port, 19...Air intake, 19a...Air intake passage, 20...Panel radiator 20a...pipe, 20b...on-off valve, 21...supply passage, 22...Return passage, 23...Circulation pump, 24...Return temperature sensor, 25... Supply temperature sensor, 27... Branching passage, 28... Hot water heat exchanger, 29... Three-way valve, 30... Water supply passage, 31... Hot water outlet passage, 32...Water volume sensor, 33...Water volume servo, 34...Water supply temperature sensor, 35...Heat exchange hot water temperature sensor, 36...Bypass passage, 37...Bypass servo, 38...Hot water temperature sensor, 40...Controller, 41...Hot water remote control, 42... Remote control for heating.

Claims

1. In a combustion device that supplies combustion gas to a burner by driving a combustion fan located inside the enclosure, and heats a flowing liquid by combustion in the burner, When a limiting condition based on the current flowing through the motor of the combustion fan is met, a capacity limiting means is provided to perform a capacity limiting process to limit the capacity of the combustion fan. A temperature sensor that detects relevant temperatures that affect the internal temperature of the housing, An adjustment means that reduces the difficulty of satisfying the limiting condition as the relevant temperature detected by the temperature sensor increases, A combustion device characterized by being equipped with the following features.

2. In the combustion apparatus according to claim 1, The temperature sensor is an ambient temperature sensor that detects the ambient temperature of the environment in which the housing is installed, as the related temperature. A combustion device characterized by the following features.

3. In the combustion apparatus according to claim 1 or claim 2, A circulation circuit through which the aforementioned liquid circulates, A circulation pump that sends the liquid in the circulation circuit in a predetermined direction, A heat exchanger is provided in the circulation circuit and heats the liquid by heat exchange with the combustion exhaust generated by combustion in the burner. Equipped with, The temperature sensors include a supply temperature sensor that detects the temperature of the liquid flowing out of the heat exchanger as the associated temperature, and a return temperature sensor that detects the temperature of the liquid flowing into the heat exchanger as the associated temperature. A combustion device characterized by the following features.

4. In the combustion apparatus according to claim 1 or claim 2, The temperature sensor is an air supply temperature sensor that detects the temperature of the air that has flowed into the housing from the outside as the associated temperature. A combustion device characterized by the following features.

5. In the combustion apparatus according to claim 1 or claim 2, The capacity limiting means executes the capacity limiting process when the value of the current flowing to the motor of the combustion fan reaches an upper limit, with the limiting condition being: The aforementioned adjusting means is If the relevant temperature is below a predetermined threshold temperature, the value of the current flowing to the motor of the combustion fan is invalidated when it reaches the upper limit, When the relevant temperature is equal to or greater than the threshold temperature, it is considered that the value of the current flowing to the motor of the combustion fan has reached the upper limit. A combustion device characterized by the following features.

6. In the combustion apparatus according to claim 1 or claim 2, The capacity limiting means executes the capacity limiting process when the value of the current flowing to the motor of the combustion fan reaches an upper limit, with the limiting condition being: The adjusting means reduces the upper limit as the relevant temperature increases. A combustion device characterized by the following features.

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