A neighbor of mine went away for a couple days and I agreed to build fires in his small house for him so stuff wouldn't freeze. He's got a small stove that works well, but no damper on the pipe. I gave him a ride to town the other day and mentioned the lack of damper. He said the stove manufacturer said no damper was needed. I suggested a lot of heat was passing up the pipe, and he was burning a lot more wood than if he put on a damper. He didn't seem impressed at my reasoning, preferring to rely on the manufacturers suggesstion. Great neighbor, really friendly guy, but got this idea in his head. I suppose the polite, most neighborly thing to do is not bring it up again.