Just got finished cleaning the chimmney and pipe after 1st year burning the summit Classic, the chimmney just had a very light black powdery residue and the stainless chimmney cap just had a little soot but no creosote on it, the pipe just above the stove had an 1/8 inch buildup of the same fine powdery residue as the chimmney, I think this is pretty clean for a non cat stove.