PURPOSE: To facilitate removal of an adherend in a flue pipe by exposing an actuator connected with a scrubbing tool accomodated in an accomodation part biased from a min flow part of burned gas and provided at an end of the flue pipe from the end of the flue pipe end, and reciprocating the actuator toward the interior of the flue pipe.

CONSTITUTION: A lower end of a smoke exhaust pipe 30 is protruded slightly downwardly from a transverse pipe 31, and an accomodation part 33 of a predetermined volume is formed at the protrusion part in which accomodation part a wire brush 42 (scrubbing) is accomodated. A movable actuator 46 composed of a piano wire is coupled with a lower part of a core material of the wire brush 42. The actuator 46 is exposed from the lower end of the smoke exhaust pipe 30 to the outside, and is vertically moved toward the interior of the smoke exhaust pipe 30 with a driver 50. More specifically, the actuator 46 is held between a driving roller 53 mounted facing a bracket 51 hung on and fixed to the lower end of the smoke exhaust pipe 30 and a press roller 54, and a motor is forwardly and reversely rotated to vertically move the actuator 46 toward the interior of the smoke exhaust pipe 30.