PURPOSE: To imporve the workability in assembly process and simplify the maintenance and checking by a method wherein the installing position of a wick for a wick supporting metal member is made adjustable.

CONSTITUTION: When a wick vertical moving shaft 33 is rotated about 60° in counterclockwise direction with an operating lever, an arm plate 36 is also rotated in counterclockwise direction on the axis of the wick vertical moving shaft 33. At this time, an engaging protrusion 37 of the arm plate 36 is engaged with a engaging hole 24 of a forward raising adjustable plate 23, accordingly, a rotating movement arm receiving plate 18 of the arm plate 36 is moved upward, consequently, a wick body 14 is also moved upward. At the burning position of the wick body 14 after upward movement thereof, when the burning changes to the unstable condition due to the inadequate position of tha wick body 14, a seal member 29 of an operation circular hole openly provided on the horizontal surface 13a of a wick guide outer cylinder 13 is removed, then a screw driver is inserted, an adjusting screw 27 is turned, then the adjusting plate 23 is moved vertically for the arm receiving plate 18 fixed to the wick supporting metal member 17, thus, the height of the wick is adjusted by optimizing the position of the engaging hole 24.