Last night the whole family was sitting in the room one of the Oslos is in. The stove was about half way through it's burn cycle. One of my kids opened the door to let the dogs out and about 10 seconds after she closed it there was a small explosion inside the stove, which blew ashes past the front door gasket and onto the ash lip, smoke and ash out the air intake in the back, and smoke out all of the double wall stovepipe joints. I am assuming that for some reason, opening the house door reversed the draft momentarily, and the conditions in the stove were just right to detonate the gasses. No harm seems to have be done, but it sure got everyone's attention.