I've got a 1976 Comforter from the stove works in Lochmere, NH. In the past I was always able to regulate a steady burn with 7 inch smoke pipe going into a fireplace smoke chamber to a 12 inch x 12 inch clay flue. Now I've got a 6 inch insulated, stainless steel flue liner inside my 12 x 12 clay flue. I installed it after learning that it would be much safer and after having to put up with too much liquid creosote dripping down the walls of the fireplace. This setup has caused my seasoned hardwood fire to "runaway" several times since the beginning of the 09 heating season. Three sticks of smoldering wood sometimes begin to burn violently and when my wife and I panic and shut the air feed all the way down the fire begins to gulp air down the chimney and the resulting mini-explosions actually lift the kettle lid and a nasty flame blows out! I have talked to several people in the business about this, because I am very concerned. One fellow says that a barometric damper will not fix the problem. He says what I need is an electric "paddle wheel" called a draft inducer. Another guy at the stove shop says that my Comforter stove is probably no longer air tight; says all the seams need to be re-sealed (although it looks pretty air tight to me). He says that I should install a 6 inch cast iron damper inside my exit pipe to regulate my chiminey draft. Can somebody with real experience advise me about this awful problem?