Abstract: A control unit includes a scale detection unit for detecting, while the a burner provides combustion, occurrence of clogging with scale in a tube of a heat exchanger, and an output unit for outputting a result of a detection by the scale detection unit, a storage stores information including a numerical value representing how many times a surface temperature of the heat exchanger measured by a temperature measuring unit exceeds at least one of a plurality of threshold values. While the burner provides combustion when the surface temperature measured by the temperature measuring unit exceeds at least one of the plurality of threshold values the scale detection unit adds a predetermined value to the numerical value in the storage and when the numerical value attains a defined value or more the scale detection unit detects occurrence of clogging with scale.

Abstract: A control unit includes a scale detection unit for detecting, while the a burner provides combustion, occurrence of clogging with scale in a tube of a heat exchanger, and an output unit for outputting a result of a detection by the scale detection unit, a storage stores information including a numerical value representing how many times a surface temperature of the heat exchanger measured by a temperature measuring unit exceeds at least one of a plurality of threshold values. While the burner provides combustion when the surface temperature measured by the temperature measuring unit exceeds at least one of the plurality of threshold values the scale detection unit adds a predetermined value to the numerical value in the storage and when the numerical value attains a defined value or more the scale detection unit detects occurrence of clogging with scale.

Abstract: By a feedback arithmetic operation based on a temperature deviation, an input number is set which corresponds to a requested heat quantity generation, which is a controlled object, to a hot water supply apparatus. The temperature deviation is calculated by correcting a deviation of a tapping temperature with respect to a set hot water temperature with use of a Smith compensation temperature calculated by a Smith compensator for predicting a variation in a tapping temperature prior to an elapse of a dead time corresponding to a detection lag of the tapping temperature. The Smith compensator calculates a Smith compensation temperature to be used in the next control cycle based on the input scale number, the present Smith compensation temperature, and a time constant set in accordance with a flow rate of the hot water supply apparatus.

Abstract: A conversion factor learning unit successively updates a temperature conversion factor by learning a performance ratio of an output heat quantity with respect to an input scale number corresponding to a requested heat quantity generation to a hot water supply apparatus. The temperature conversion factor learned by the conversion factor learning unit is reflected in arithmetic operation of an FF scale number by a feedforward control unit and arithmetic operation of the FB scale number by the feedback control unit. An integral control in the feedback control unit is preferably turned off.

Abstract: A conversion factor learning unit successively updates a temperature conversion factor by learning a performance ratio of an output heat quantity with respect to an input scale number corresponding to a requested heat quantity generation to a hot water supply apparatus. The temperature conversion factor learned by the conversion factor learning unit is reflected in arithmetic operation of an FF scale number by a feedforward control unit and arithmetic operation of the FB scale number by the feedback control unit. An integral control in the feedback control unit is preferably turned off.

Abstract: By a feedback arithmetic operation based on a temperature deviation, an input number is set which corresponds to a requested heat quantity generation, which is a controlled object, to a hot water supply apparatus. The temperature deviation is calculated by correcting a deviation of a tapping temperature with respect to a set hot water temperature with use of a Smith compensation temperature calculated by a Smith compensator for predicting a variation in a tapping temperature prior to an elapse of a dead time corresponding to a detection lag of the tapping temperature. The Smith compensator calculates a Smith compensation temperature to be used in the next control cycle based on the input scale number, the present Smith compensation temperature, and a time constant set in accordance with a flow rate of the hot water supply apparatus.

Abstract: An exhaust channel of a combustion apparatus is defined by an upper sloping plate and a lower sloping plate. The lower sloping plate contains a rising part and a lower sloping wall. A water droplet baffle plate is positioned across an interspace from the rising part. The interspace is brought into fluid communication with the exhaust channel through an upper surface opening while being brought into fluid communication with a bottom of a heat exchange chamber through a communication opening. A collision wall part of the water droplet baffle plate is disposed in close proximity to a lowest fine tube so as to oppose against a combustion exhaust flow. Water droplets adhere onto the collision wall part. Water droplets failing to adhere to the collision wall part fall through the upper surface opening positioned over an upper end of the collision wall part.