GaryFerg wrote:The damper really stays open all the time in other words full dampening.
If the damper is wide open all the time, you need more damper! I have that problem. On windy days I open my clean out door to bring the draft within specs. I don't recommend doing that. I happen to be able to do it safely. I've been temped to add another damper and might for next yr. Also, I've seen people use an 8" damper on a 6" pipe. Maybe I'll do that.