PURPOSE: To enable a bloweralone be operated even at times other than heating operation, without affecting the control of the blower in the heating operation, by providing a heating mode and a blowing mode, and ensuring that the blower is not controlled by operations of a blowing operating means in the heating mode.

CONSTITUTION: A controller 30 comprises a combustion controlling circuit 37 and a fan-controlling circuit 38. A heating mode of operating both the circuit 37 and the circuit 38 and a blowing mode of operating only the circuit 38 are provided. When an operation signal is supplied from a heating switch 31, the circuit 38 selects the heating mode, in which it operates a convection fan 13 on a control signal from the circuit 37. Only when the signal from the switch 31 is absent, the circuit 38 selects the blowing mode, in which it operates the convection fan 13 on a setting signal from an air cleaner-operating part 33. Thus, in the heating mode, the rotational frequency of the fan 13 is not affected by the set condition of the operating part 33, and is controlled to an appropriate rotational frequency according to the combustion output of a burner operated according to the set condition of a room temperature controller 32.