I've tried searching this topic and the closest I got was the Tarm leaking smoke. I'm not sure its the same problem or not. When I start my boiler I set up the kindling and stuff and close both doors, turn on the fan, and leave the flue open (usually for about 15-30 minutes to get a bed of coals). About a month ago I noticed that my furnace room had started to fill with smoke when I did this. At first I figured it was the wind, since that happens sometimes on windy days. But then I noticed this was happening on less windy days, and now it happens every time I start the furnace. The smoke seems to be coming out of every seam from the top of and upper sides of the outer covering (the stuff attached to the insulation) It seems to stop when I close the flue, whether its gasifying or not. I have cleaned out the chimney twice and scraped the ash out of the back of the furnace and it still is happening. The lever arm that cleans the heat exchanger tubes works as great as the day I got it. Does anyone know what is going on?