such as a gas log, you will want to keep the doors completely open as well. it is very important to remember that the mesh screen should remain closed at all times in the burning process. if the fireplace is see-through, the doors should mirror each other, if one door is closed then the other door should be closed as well.
if i do not want all the air going up the chimney, can i close my damper part way on my wood burning fireplace?
do not partly close the damper. this apparatus should always be completely open when the wood burning fireplace is in use. if you are using gas logs, 