I was getting a fire going today and i lost track of time while i was doing something upstairs and had the air all the way open. I come downstairs to that smell when you first break in the stove. Stove tops at 500 but the double wall pipe was at 500 too. Normally when im burning with a 500 stovetop that pipe is at like 175 outside temp. Heard some crackling in the stove pipe right above the stove and im pretty certain it was creosote burning. Didnt really sound like the metal expanding and contracting