So I promised a while back that I would post pics of my Kuuma VF 100 clean out in another thread. I cleaned it 3-4 weeks back and have been busy so never got around to posting them up. Got a chance today now. As you can see from the pics inside the heat exchanger there is only white-grey powdery ashes. I took a vacuum and cleaned them up. Then proceeded to the back of the furnace and cleaned that area out. I checked the chimney and it's clean as a whistle. I'm not even going to run a brush down it. Last yr I burned 2 yr seasoned honey locust and white oak. My stove pipe temps were around 230-250F 16" from the furnace. I'm extremely pleased with this furnace and recommend it to anyone who wants a good clean burning unit. Darryl and Garret Lamppa do a wonderful job answering questions on the phone and here. Awesome service!!!!