Buddy of mine waited all summer and fall for some fancy soapstone stove coming from Finland but it never showed up. Winter set in and he needed heat so he purchased what he could get which was a F2500m. He had the same installer put in the chimney that did my recent BK install so it's all good and professional. I believe the chimney ended up at 18' with his ceiling height and attic. Problem is he can only get 6-7hrs on a full load with it turned all the way down and it's pouring out the heat to the point that he doesn't do full loads anymore because the house gets too hot. My advice to him was the dollar bill test but he tried it this evening after it cooled down and said the door is tight all the way around. Too much draft with 18' chimney? Any other ideas?