Abstract: A mechanism for mounting within a firebox of an existing fireplace to control the opening and closing of a pivotally mounted flue damper plate. A vertically extending connecting rod is connected at its upper end to the damper plate. An L-shaped control rod is eccentrically connected to the lower end of the connecting rod adjacent the rear of the firebox for vertically moving the connecting rod upon rotation of the control rod. The control rod is rotatably mounted on and extends beneath a usual fuel holding grate supported on the floor of the firebox. The front end of the control rod extends upwardly in front of and above the grate when the damper is in closed position obstructing placement of fuel on the grate and lighting of a fire therein and providing a visual indication that the damper plate is closed.