As I mentioned in another recent post after two seasons of burning I recently cleaned the flue that's connected to my Oslo. The flue pipe is 6" dia. round, single-wall solid stainless that was wrapped with insulation at installation. It sits inside about 25 ft. of 12" x 12" ceramic liner with block-off plates at top and bottom.
When I pulled the chimney cap I noticed (with some disappointment) a fair amount of creosote within the cap and at the top of the flue pipe. However, on closer inspection of the flue I found that almost all creosote had formed within about 2 ft. from the top of the pipe. The farther down I looked cleaner the flue looked. I can only assume that this occurred because the insulated flue gets hot enough during operation to burn off the creosote that forms during start-ups and cool-downs. Apparently the flue only stays cold enough at the very top allowing some creosote formation.
I'm concerned about both clean operation of our wood stove and prevention of chimney fires. This experience has given me some reassurance on both counts. I thought I'd share in case others have the same concern and are considering whether its worth it to insulate their flue.
When I pulled the chimney cap I noticed (with some disappointment) a fair amount of creosote within the cap and at the top of the flue pipe. However, on closer inspection of the flue I found that almost all creosote had formed within about 2 ft. from the top of the pipe. The farther down I looked cleaner the flue looked. I can only assume that this occurred because the insulated flue gets hot enough during operation to burn off the creosote that forms during start-ups and cool-downs. Apparently the flue only stays cold enough at the very top allowing some creosote formation.
I'm concerned about both clean operation of our wood stove and prevention of chimney fires. This experience has given me some reassurance on both counts. I thought I'd share in case others have the same concern and are considering whether its worth it to insulate their flue.