Woodstove problem, Vermont Castings Defiant

You can shut the stove pipe damper completely closed and an air tight stove shouldn't smoke. But, after awhile the door gasket flattens down and lets a little air in, making the fire a tiny bit less controllable. But, smoke can seep out if the stove pipe damper is closed too much. The same applies if the stove has a damper built in . The gaskets are replaceable.

The VC Defiant doesn't have a damper (unless you installed one in your pipe). You control it with a fresh air intake lever. I have mine setup so that it draws fresh air from outside the house. Safer.