JP2008256271A - Forced air supply type combustion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a supply gas amount to a burner 2 from being lowered when a turbo fan is used as a combustion fan 12 and an inner pressure of a combustion casing 1 is raised by closing of an air supply and exhaust passage and gas injection from a gas nozzle 7a is restrained. <P>SOLUTION: In the forced air supply type combustion device, a target rotational frequency of the combustion fan 12 set in accordance with a required combustion amount of the burner 2 is increased and corrected in accordance with increase of a closing degree of the air supply and exhaust passage, and a target current of a gas proportional valve 9 set in accordance with the required combustion amount is increasingly corrected in correspondence with increase of the closing degree. The smaller the target rotational frequency and the target current are, the larger the increase and correction amounts of the target rotational frequency and the target current when the closing degree is increased are. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a forced air supply combustion apparatus including a combustion housing with a built-in burner, a gas proportional valve provided in a gas supply path for the burner, and a combustion fan for supplying combustion air into the combustion housing.

  Conventionally, as this type of combustion apparatus, a fan rotation speed setting means for setting a target rotation speed of a combustion fan according to the required combustion amount of the burner, and a target current for energizing the gas proportional valve according to the required combustion amount of the burner. Proportional valve current setting means for setting, blockage degree detection means for detecting the blockage degree of the supply / exhaust passage to the combustion housing, and a fan for correcting the target rotational speed of the combustion fan according to the blockage degree detected by the blockage degree detection means What is provided with a rotation speed correction | amendment means is known (for example, refer patent document 1).

  If the degree of blockage of the supply / exhaust passage to the combustion housing exceeds a certain level, the amount of air supplied to the combustion housing will remain the required combustion of the burner even if the combustion fan is rotated at the target rotational speed set by the fan rotational speed setting means. The target air quantity corresponding to the quantity is reduced, and combustion failure occurs due to air shortage. According to the above conventional example, the target rotational speed is corrected to increase with the increase in the degree of blockage detected by the blockage degree detection means, so that even if the supply / exhaust passage is blocked, the combustion air of the target air amount burns. Supplying into the housing prevents the occurrence of poor combustion. The energization current to the gas proportional valve is maintained at the target current set by the proportional valve current setting means even if the degree of blockage is increased so that the burner combustion amount is maintained at the required combustion amount.

  By the way, although a combustion fan is generally comprised by a sirocco fan, the forced air supply type combustion apparatus using a turbo fan as a combustion fan is also known conventionally (for example, refer patent document 2). A turbofan has a high static pressure, and has an advantage that a decrease in air volume due to blockage of a supply / exhaust passage is smaller than a sirocco fan.

However, it has been found that the following problems occur when a turbofan is used. In other words, since the turbo fan has a high static pressure, if the target rotation speed is increased and corrected as the degree of blockage of the supply / exhaust passage increases, the internal pressure of the combustion housing becomes considerably high, and the injection of fuel gas from the gas nozzle is suppressed, The amount of gas supplied to the burner decreases. In particular, when the required combustion amount of the burner is small, that is, when the target rotational speed and the target current set by the fan rotational speed setting means and the proportional valve current setting means are small, the flame is too close to the burner due to insufficient gas amount. Becomes red hot and tends to cause heat loss.
Japanese Patent No. 3029547 JP 2003-240229 A

  In view of the above, the present invention uses a turbo fan as a combustion fan so as to suppress a decrease in the air volume due to blockage of the supply / exhaust passage and to prevent a decrease in the amount of gas supplied to the burner. The object is to provide a high-performance forced-air combustion apparatus.

  In order to solve the above-mentioned problems, the present invention provides a combustion housing incorporating a burner, a gas proportional valve provided in a gas supply path for the burner, a combustion fan for supplying combustion air into the combustion housing, Fan rotation speed setting means for setting the target rotation speed of the combustion fan according to the required combustion amount, proportional valve current setting means for setting a target current to be supplied to the gas proportional valve according to the required combustion amount of the burner, A forced air supply system comprising: a blockage degree detection means for detecting the degree of blockage of the supply / exhaust passage with respect to the engine; and a fan rotation speed correction means for correcting the target rotation speed of the combustion fan according to the blockage degree detected by the blockage degree detection means Proportional valve current correction means for correcting the target current of a gas proportional valve to increase with an increase in the degree of obstruction detected by the degree of obstruction detection means in a combustion apparatus comprising a turbo fan as a combustion fan Characterized in that it obtain.

  According to the present invention, the target speed of the gas proportional valve is increased even if the internal pressure in the combustion housing is increased by correcting the target rotational speed of the combustion fan composed of a turbofan to increase as the degree of blockage of the supply / exhaust passage increases. Since the current is corrected to increase, a decrease in the amount of gas supplied to the burner can be suppressed.

  Here, when the required combustion amount of the burner is large and the target rotational speed set in the fan rotational speed setting is large, in order to obtain the target air amount corresponding to the required combustion amount with the degree of blockage of the supply / exhaust passage increased. Therefore, it is necessary to greatly increase the rotational speed of the combustion fan from the target rotational speed, which increases noise and adversely affects the durability of the combustion fan. In this case, even if the rotation speed of the combustion fan is not increased from the target rotation speed, the internal pressure of the combustion housing becomes considerably high as the degree of blockage of the supply / exhaust passage increases. Therefore, in order to supply the burner with an amount of fuel gas corresponding to the required combustion amount, the current of the gas proportional valve needs to be significantly increased from the target current. However, when the required combustion amount of the burner is large, the target current set by the proportional valve current setting means becomes a current value that opens the gas proportional valve close to the maximum opening, so the gas proportional valve corresponds to the required combustion amount. The amount of fuel gas cannot be opened to such an extent that it can be supplied to the burner.

  On the other hand, when the required combustion amount of the burner is small and the target rotational speed set by the fan rotational speed setting means is small, the target air amount corresponding to the required combustion amount is obtained with the degree of blockage of the supply / exhaust passage increased. Thus, even if the target rotational speed is increased and corrected at a required ratio, the rotational speed of the combustion fan does not become so high, and problems such as noise and deterioration of the durability of the combustion fan do not occur. Further, in this case, since the target current set by the proportional valve current setting means is small, the gas proportional valve can be opened up to an opening at which the fuel gas corresponding to the required combustion amount can be supplied to the burner.

  Considering the above, in the present invention, the fan rotation speed correction means and the proportional valve current correction means are the blockage degree detection means as the target rotation speed and the target current set by the fan rotation speed setting and the proportional valve current setting means become smaller. It is desirable that the target rotational speed and the target current increase correction value when the detected degree of blockage increases be increased. According to this, when the target rotational speed and the target current set by the fan rotational speed setting means and the proportional valve current setting means are large, the target rotational speed and the target current increase so much even if the blockage degree increases. Since it is not corrected, noise can be reduced and deterioration of the durability of the combustion fan can be prevented. Further, when the target rotational speed and the target current set by the fan rotational speed setting and the proportional valve current setting means are small, the target rotational speed and the target current are corrected to be relatively large when the blocking degree increases. Thus, air and fuel gas corresponding to the required combustion amount can be supplied to the combustion housing and the burner, respectively. Therefore, it is possible to prevent the flame from being too close to the burner due to the shortage of gas and causing heat loss of the burner.

  Hereinafter, an embodiment in which the present invention is applied to a water heater that is a forced-air combustion apparatus will be described. This water heater is provided with a combustion housing 1. A burner 2 including a plurality of unit burners 2 a is disposed in the combustion housing 1, and a heat exchanger 3 for hot water supply is disposed above the burner 2. The heat exchanger 3 has a large number of endothermic fins 3a and endothermic tubes 3b that penetrate these endothermic fins 3a. An upstream water supply passage 4 and a downstream hot water discharge passage 5 are connected to the heat absorption pipe 3b. Then, water supplied from the water supply path 4 to the heat exchanger 3 is heated by heat exchange with the combustion exhaust of the burner 2 in the heat exchanger 3, and the heated hot water is sent to the hot water discharge path 5, and the hot water supply path 5. The hot water is discharged from a hot water tap (not shown) at the downstream end.

The plurality of unit burners 2a constituting the burner 2 are grouped into _first and second sets of burner groups 2 ₁ and 2 ₂ . The first and second gas manifolds 7 ₁ and 7 ₂ corresponding to the two burner groups 2 ₁ and 2 ₂ are provided at the downstream end of the gas supply path 6 with respect to the burner 2, and each gas manifold is provided. Fuel gas is supplied from the plurality of gas nozzles 7a provided at 7 ₁ and 7 ₂ to the corresponding unit burners 2a of the respective burner groups 2 ₁ and 2 ₂ . The gas supply path 6 is provided with a main valve 8 and a gas proportional valve 9 on the downstream side thereof. The gas supply path 6 is branched into a pair of branch paths corresponding to the first and second gas manifolders 7 ₁ and 7 ₂ on the downstream side of the gas proportional valve 9, and the first gas manifold 7 to the branch passage for the ₁ first capacity switching valve 10 ₁ is interposed, the second capacity switching valve 10 ₂ is interposed in the branch passage of the second gas manifold 7 for _2.

Then, in a relatively small area is required combustion amount of burners 2, which is calculated as described below, by opening _a first capacity switching valve 10, performs a small capacity operation to burn only the first burner group 2 ₁ , when the request combustion rate is larger than the combustion amount obtained in the first burner group 2 ₁ when the maximum opening degree of the gas proportional valve 9, also the second capacity switching valve 10 ₂ is opened, the first And the second both burner groups 2 ₁ , 2 ₂ are burned.

  The combustion exhaust from the burner 2 passes through the heat exchanger 3 and is then discharged from the upper end of the combustion housing 1 through the exhaust cylinder 11. A combustion fan 12 is connected to the bottom surface of the combustion housing 1, and combustion air is supplied into the combustion housing 1 by the operation of the combustion fan 12. Here, the combustion fan 12 is constituted by a turbo fan. The turbofan has a high static pressure, and has an advantage that a reduction in air volume due to blockage of the supply / exhaust passage to the combustion housing 1 is smaller than that of the sirocco fan.

  The water supply path 4 is provided with a water amount sensor 13 and a water amount adjustment valve 14, and further, a water supply temperature sensor 15 for detecting the temperature of the water supplied to the heat exchanger 3 is provided. In addition, a tapping water temperature sensor 16 that detects the temperature of hot water fed from the heat exchanger 3 is provided in the tapping channel 5.

The water heater further includes a controller 17 that controls the main valve 8, the gas proportional valve 9, the capacity switching valves 10 ₁ and 10 ₂ , the combustion fan 12, and the water amount adjustment valve 14. Detection signals from the water amount sensor 13, the feed water temperature sensor 15, and the tapping temperature sensor 16 are input to the controller 17. A remote controller 18 is connected to the controller 17, and a set hot water temperature instruction signal set by the remote controller 18 is input to the controller 17.

As shown in FIG. 2, the controller 17 includes, as functional means, a required combustion amount calculation means 171, a blockage degree detection means 172 that detects the blockage degree of the supply / exhaust passage of the combustion housing 1, and a required combustion amount calculation means 171. Fan rotation speed setting means 173 for setting the target rotation speed of the combustion fan 12 according to the calculated required combustion amount, and fan rotation speed for correcting the target rotation speed according to the blockage degree detected by the blockage degree detection means 172 Detected by the correcting means 174, the proportional valve current setting means 175 for setting the target current to be supplied to the gas proportional valve 9 according to the required combustion amount calculated by the required combustion amount calculating means 171, and the closing degree detecting means 172. Proportional valve current correction means 176 for correcting the target current according to the degree of blockage, fan control means 177 for controlling the combustion fan 12, main valve 8, gas proportional valve 9 and capacity switching valve 0 with _1, and 10 ₂ burner control unit 178 for controlling, and a water quantity control means 179 for controlling the water amount adjustment valve 14.

  The required combustion amount calculation means 171 calculates the required combustion amount from the water amount detected by the water amount sensor 13, the water temperature detected by the feed water temperature sensor 15, and the set hot water temperature set by the remote controller 18. That is, the required combustion amount is calculated as the required combustion amount for heating the water passed through the heat exchanger 3 at the detected water amount and the detected water temperature to the set hot water temperature.

  The blockage degree detection means 172 utilizes the phenomenon that the fan current (current flowing to the fan motor of the combustion fan 12) decreases with an increase in the blockage degree of the supply / exhaust passage when the rotation speed of the combustion fan 12 is constant. Thus, the blockage degree of the supply / exhaust passage is calculated based on the fan rotation speed and the fan current detected by the rotation speed sensor 121 and the current sensor 122 attached to the combustion fan 12.

The fan rotation speed setting means 173 changes the target rotation speed of the combustion fan 12 from the minimum rotation speed to the maximum rotation speed in the normal control range when the required combustion amount changes between the lower limit and the upper limit of the range in which the small capacity operation is performed. When the required combustion amount changes between the lower limit and the upper limit of the range in which the large capacity operation is performed, the target rotational speed of the combustion fan 12 is similarly set within the normal control range. It is variably set according to the required combustion amount between the minimum speed and the maximum speed. In addition, if the opening degree of the gas proportional valve 9 is the same, that is, if the combustion amount of each unit burner 2a is the same, the combustion amount of the entire burner 2 at the time of small capacity operation is 1/2 of that at the time of large capacity operation. but becomes, it will flow to the combustion fan 12 second burner group 2 ₂ half of the air is not burned supplied from during operation small capacity. Therefore, to supply the amount of air corresponding to the combustion quantity to a first respective unit burner 2a of the burner group 2 ₁ during combustion, the normal control range target rotational speed of the combustion fan 12 also during operation small capacity It is necessary to variably set between the minimum rotation speed and the maximum rotation speed according to the required combustion amount.

  The proportional valve current setting means 175 sets the target current of the gas proportional valve 9 between the minimum current and the maximum current in the normal control range when the required combustion amount changes between the lower limit and the upper limit of the range in which the small capacity operation is performed. When the required combustion amount changes between the lower limit and the upper limit of the range in which large capacity operation is performed, the target current of the gas proportional valve 9 is similarly set to the minimum current in the normal control range. Between the maximum current and the maximum current according to the required combustion amount. The target current of the gas proportional valve 9 can be variably set in proportion to the rotational speed of the combustion fan 12. Even in this case, since the rotation speed of the combustion fan 12 changes according to the required combustion amount, the target current of the gas proportional valve 9 is set according to the required combustion amount.

  The fan rotation speed correction means 174 and the proportional valve current correction means 176 correct the target rotation speed and the target current when the blockage degree of the supply / exhaust passage detected by the blockage degree detection means 172 exceeds a predetermined lower limit value. To do. When the degree of blockage exceeds a predetermined upper limit value, combustion is stopped as will be described later.

  Here, when the required combustion amount of the burner 2 is large and the target rotational speed set by the fan rotational speed setting means 173 is large, in order to obtain the target air amount corresponding to the required combustion amount with the degree of blockage increased. Therefore, it is necessary to greatly increase the rotational speed of the combustion fan 12 from the target rotational speed, which increases noise and adversely affects the durability of the combustion fan 12. In this case, even if the rotation speed of the combustion fan 12 is not increased from the target rotation speed, the internal pressure of the combustion housing 1 is supplied and exhausted because the turbofan having a high static pressure is used as the combustion fan 12. Increased by increasing the degree of blockage of the road. Therefore, the gas injection from the gas nozzle 7a is suppressed. Therefore, in order to supply the burner 2 with an amount of fuel gas corresponding to the required combustion amount, it is necessary to significantly increase the current of the gas proportional valve 9 from the target current. However, when the required combustion amount of the burner 2 is large, the target current set by the proportional valve current setting means 175 becomes a current value that opens the gas proportional valve 9 close to the maximum opening. The amount of fuel gas corresponding to the amount cannot be opened to such an extent that it can be supplied to the burner.

  On the other hand, when the required combustion amount of the burner 2 is small and the target rotational speed set by the fan rotational speed setting means 173 is small, the target air amount corresponding to the required combustion amount with the degree of blockage of the supply / exhaust passage increased. Therefore, even if the target rotational speed is increased and corrected at a required ratio, the rotational speed of the combustion fan 12 is not so high, and problems such as noise and deterioration of the durability of the combustion fan 12 do not occur. Further, in this case, since the target current set by the proportional valve current setting means 175 is small, the gas proportional valve 9 can be opened to an opening at which an amount of fuel gas corresponding to the required combustion amount can be supplied to the burner. .

  Therefore, in the present embodiment, the target rotation when the blockage degree detected by the blockage degree detection means 172 increases as the target rotation speed and the target current set by the fan rotation number setting means 173 and the proportional valve current setting means 175 become smaller. The increase correction value of the number and the target current is made larger. This point will be described in detail with reference to FIG.

  The target rotational speed set by the fan rotational speed setting means 173 is the maximum rotational speed Nmax (eg, 330 Hz) in the normal control range of the combustion fan 12, and the target current set by the proportional valve current setting means 175 is the gas proportional valve. When the maximum current Imax (for example, 167 mA) is 9 in the normal control range, as shown by the lines AN and AI in FIG. 3, the blockage degree is between 65% as the lower limit value and 85% as the upper limit value. When it is within the range, the target rotational speed and the target current are increased and corrected. The target rotational speed set by the fan rotational speed setting means 173 is the minimum rotational speed Nmin (for example, 155 Hz) in the normal control range of the combustion fan 12, and the target current set by the proportional valve current setting means 175 is gas. In the case of the minimum current Imin (for example, 70 mA) in the normal control range of the proportional valve 9, as shown by the lines BN and BI in FIG. 3, the closing degree is 75% as the lower limit and 90% as the upper limit. When the range is between, the target rotational speed and the target current are increased and corrected.

  The target rotational speed is increased and corrected to a value obtained by multiplying the target rotational speed set by the fan rotational speed setting means 173 by a correction value (correction coefficient) K. Further, the target current is increased and corrected to a value obtained by adding the correction value ΔI to the target current set by the proportional valve current setting means 175. These correction values K and ΔI increase with an increase in the occlusion degree when the occlusion degree is equal to or greater than the lower limit value, and become maximum when the occlusion degree reaches the upper limit value. Here, when the target rotational speed and the target current are the maximum rotational speed Nmax and the maximum current Imax, the maximum values Ka and ΔIa of the correction values K and ΔI are set to be relatively small (for example, Ka = 1.05, ΔIa = 3 mA), correction values K and ΔI maximum values Kb and ΔIb when the target rotational speed and the target current are the minimum rotational speed Nmin and the minimum current Imin, respectively, are set to be relatively large (for example, Kb = 1.3). , ΔIb = 25 mA).

  When the target rotational speed set by the fan rotational speed setting means 173 is in the range between the maximum rotational speed Mmax and the minimum rotational speed Nmin, the target rotational speed is linear between the lines AN and BN in FIG. Increase correction to the interpolated value. Similarly, when the target current set by the proportional valve current setting means 175 is in the range between the maximum current Imax and the minimum current Imin, the target current is linearly interpolated between the lines AI and BI in FIG. Increase the value to the corrected value. Further, when the target rotational speed set by the fan rotational speed setting means 173 is in a range between the maximum rotational speed Mmax and the minimum rotational speed Nmin, the blockage degree for correcting the increase in the target rotational speed and the target current is set. The lower limit value and upper limit value that define the range are also set to values obtained by linear interpolation.

Next, control by the controller 17 at the time of hot water supply will be described. When the hot water tap is opened and water is passed through the heat exchanger 3 and the amount of water detected by the water amount sensor 13 exceeds the minimum operating water amount (for example, 2.7 liters / minute), the fan control means 177 causes the combustion fan 12 to A pre-purge operation is performed by operating for a predetermined time at a predetermined pre-purge speed. Thereafter, the gas proportional valve 9 with the main valve 8 to be first capacity switching valve 10 ₁ transgressions opened by the burner control unit 178 is opened to a predetermined ignition angle, an igniter (not shown in the figure) in this state is actuated The burner 2 is ignited. At this time, the combustion fan 12 is operated at a predetermined ignition speed. After ignition, the combustion control shown in FIG. 4 is executed.

In the combustion control, first, in step S1, the target rotational speed set by the fan control means 177 by the rotational speed setting means 173 for the combustion fan 12 (if corrected by the rotational speed correction means 174, the corrected target is set. When the target current set by the proportional valve current setting means 175 is corrected by the burner control means 178 by the proportional valve current setting means 175, the correction is made. Proportional control to energize the later target current) is performed. In the proportional control, when the first and second capacity switching valves 10 ₁ and 10 ₂ are controlled to open and close in accordance with the required combustion amount, and the detected temperature of the tapping temperature sensor 16 does not reach the set hot water temperature. Performs control to reduce the amount of water until the temperature detected by the tapping temperature sensor 16 rises to the set hot water temperature by the water amount adjusting valve 14.

  Next, in step S2, it is determined whether the blockage degree of the supply / exhaust passage detected by the blockage degree detection means 172 is less than or equal to an upper limit value. Whether or not is equal to or greater than the lower limit is determined. If the blockage degree is equal to or greater than the lower limit value, the correction process is performed in step S4, and then the process proceeds to step S5. If the blockage degree is less than the lower limit value, the process proceeds directly to step S5.

  In the correction process in step S4, the target rotational speed of the combustion fan 12 is corrected by the fan rotational speed correcting means 174 as described above according to the degree of blockage, and the target current of the gas proportional valve 9 is corrected by the proportional valve current correcting means 176. Correction is made as described above according to the degree of occlusion.

  In step S5, it is determined whether or not the amount of water detected by the water amount sensor 13 is greater than or equal to the minimum operating flow rate. When the amount of water is equal to or greater than the minimum operating flow rate, the process returns to step S1 and the above process is repeated. When the amount of water becomes less than the minimum operating flow rate, the process proceeds to step S7. Further, when it is determined in step S2 that the blockage degree exceeds the upper limit value, in step S6, a process for displaying that an excessive blockage has occurred on the display unit of the remote controller 18 is performed. Proceed to step. In step S7, the main valve 8 is closed to stop the combustion and stop processing to stop the combustion fan 12 is executed.

  Here, when the target rotational speed and the target current set by the fan rotational speed setting means 173 and the proportional valve current setting means 175 are large, the target rotational speed and the target current increase correction value K when the blocking degree increases. , ΔI becomes relatively small. Therefore, noise can be reduced and deterioration of the durability of the combustion fan can be prevented. In this case, fuel gas in an amount corresponding to the required combustion amount cannot be supplied to the burner 2, but hot water at the set hot water temperature is discharged by reducing the amount of water by controlling the water amount control valve 14 by the water amount control means 179. Can do.

  Further, when the target rotational speed and the target current set by the fan rotational speed setting means 173 and the proportional valve current setting means 175 are small, the target rotational speed and the target current increase correction value K, when the blocking degree increases, ΔI becomes relatively large. Therefore, air and fuel gas in amounts corresponding to the required combustion amount can be supplied to the combustion housing 1 and the burner 2, respectively. Therefore, it is possible to prevent the flame from becoming too close to the burner 2 due to a shortage of gas and causing heat loss of the burner 2.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to this. For example, in the above embodiment, the blockage degree detection means 172 is configured to detect the blockage degree of the supply / exhaust passage based on the relationship of the fan current to the rotation speed of the combustion fan 12. It is also possible to provide an air volume sensor for detecting the degree of blockage and detect the degree of blockage from the relationship of the air flow rate with respect to the fan rotation speed.

  Further, the target rotational speed set by the fan rotational speed setting means 173 is the maximum rotational speed Nmax of the normal control range of the combustion fan 12, and the target current set by the proportional valve current setting means 175 is the normal speed of the gas proportional valve 9. In the case of the maximum current Imax in the control range, the target rotation speed and the target current may not be corrected for increase even if the blockage degree increases. Moreover, although the said embodiment applies this invention to a water heater, this invention is applicable similarly to the forced air supply combustion apparatus other than a water heater.

Explanatory drawing which shows the combustion apparatus of embodiment of this invention. The block diagram of the controller of the combustion apparatus of FIG. The graph which shows how to correct | amend a fan rotation speed and a proportional valve current. The flowchart which shows the content of the combustion control by a controller.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Combustion housing, 2 ... Burner, 6 ... Gas supply path, 9 ... Gas proportional valve, 12 ... Combustion fan, 17 ... Controller, 172 ... Blockage degree detection means, 173 ... Fan rotation speed setting means, 174 ... Fan rotation speed Correction means, 175 ... proportional valve current setting means, 176 ... proportional valve current correction means.

Claims (2)

Combustion housing with built-in burner, gas proportional valve provided in the gas supply path to the burner, combustion fan for supplying combustion air into the combustion housing, and target rotation speed of the combustion fan according to the required combustion amount of the burner Fan rotation speed setting means for setting the pressure, proportional valve current setting means for setting a target current to be supplied to the gas proportional valve according to the required combustion amount of the burner, and blockage for detecting the degree of blockage of the supply / exhaust passage to the combustion housing A forced air supply type combustion apparatus comprising: a degree detection means; and a fan rotation speed correction means for correcting a target rotation speed of the combustion fan according to the degree of blockage detected by the blockage degree detection means, wherein the combustion fan is a turbo fan In the composition,
A forced supply combustion apparatus, comprising: proportional valve current correcting means for increasing and correcting a target current energized to the gas proportional valve in accordance with an increase in the closed degree detected by the closed degree detecting means.   The fan rotation speed correction means and the proportional valve current correction means are configured to detect the blockage detected by the blockage degree detection means as the target rotation speed and the target current set by the fan rotation speed setting means and the proportional valve current setting means become smaller. The forced air supply combustion apparatus according to claim 1, wherein the target rotation speed and the target current increase correction value when the degree increases are configured to be larger.

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