Wood stove dampers have been around since the first wood stove was placed indoors. The purpose of this cast iron metal disc is to retain heat that may escape up the flue or chimney. The metal disc fits inside the stovepipe that exits from the wood stove. Most dampers are placed closely to the wood stove, generally in the first 12 to 18 inches from the stove and before the pipe exits into the masonry chimney. This allows the heat to be retained and dissipate in the area the wood stove is heating. By following a basic set of rules, you can operate the damper efficiently and safely.
Identify the position of the damper by the orientation of the metal handle that rests outside the flue pipe. The metal handle and the damper disc are in line with each other. This means that if the metal handle is in a horizontal position, the damper is flat and fully open.
Close the damper by placing the handle in a vertical position. This gives the most restriction to the fire boxe's draw of air, and the release of heat and exhaust smoke.
Open the damper fully whenever you add wood to the stove or start a fire. This will allow the greatest draw on the firebox, thus eliminating any smoke escaping the stove and entering the room.
Set the damper at two-thirds closed for when the fire is beginning to catch well and some red coals have formed under the fire. This means that the chimney is warming up and the draw is increasing. The hotter the chimney, the better the airflow, or draw, through the vertically enclosed pipe.
Close the damper fully when the wood stove has a deep set of red-orange to blue-coloured coals under the fire. This indicates the chimney is at operation temperature and the flue is drawing all the air and smoke it can handle. At this point, the wood stove is putting forth all the heat it can release, and you will want to direct that heat back into the room.
Follow all manufacturer's instructions when installing a damper. Not all wood stoves were made for such devices, though some stoves cannot operate properly without one.