Six. Immediately after cleaning the flue, depending on the method we will clean up, the smoke chamber and smoke shelf in fireplaces and that is a significant issue. We also cleanse the stove pipe and wall thimbles in equipment configurations. That means the rest is build up during the dryer https://www.google.com/maps/d/edit?mid=1Y6FoBp66BALv8qFQFh6QdMpJqLXOkQM&usp=sharing