I already know the answer to this qestion- "As long as it takes!" Question, - If you're closing off your primary air flow, and you have a stove with secondary air, and after the flue temp. drops from 750 to 600, and then you close your damper from full to 1/2 closed, and your temp. increases back up to almost 700 and stays there for awhile, but you're still getting a little white smoke out of the pipe, should you buy a lottery ticket and expect to win, and if not immediatly, how long should you continue buying lottery tickets?