WARM AIR HEATER

PROBLEM TO BE SOLVED: To set a target rotating speed of a combustion fan to achieve a proper combustion air supply amount to a combustion chamber in a warm air heater provided with the combustion fan in an exhaust path.SOLUTION: A heat exchange section 3a is disposed in the exhaust path 40 communicated with an exhaust port of the combustion chamber 3, and a combustion exhaust gas from the exhaust port is introduced thereto. The combustion fan 33 is disposed at a downstream side with respect to the heat exchange section 3a in the exhaust path 40, sucks the combustion exhaust gas of a burner 2 to the exhaust path 40, and sucks the combustion air of the burner 2 from an air supply port of the combustion chamber 3. A convection fan 4 sucks the indoor air and returns the same indoors after heat exchange processing in the heat exchange section 3a. An exhaust temperature sensor 32 detects an exhaust temperature in the exhaust path 40. A controller 25 adjusts an opening of a gas proportional valve 17 in response to a target combustion amount of the burner 2, and rotates the combustion fan 33 while setting the target rotating speed of the combustion fan 33 on the basis of the target combustion amount and the detection temperature of the exhaust temperature sensor 32.