Need advice. I’m building a two story house, around 35 feet high. Big chimney goes from the first floor, thru the roof with a cap around 5 feet above the roof. Went to buy a wood burning stove, a salesmen offered a chimney guy to estimate a cost of a chimney flue. The technician looked at chimney and said that since the chimney is so high, all oxygen in chimney will be sucked out with a fire from the stove and the stove will be very inefficient. Was the guy right about it? Is there a way to install a flue for an efficient work?