Hi all, Finally got a Saturday to work on the boiler and see if I could improve a few things. I started with the install of a Tjernlund AD-1 fan to evacuate the smoke at reloading. I just have it set to turn on manually but will install a micro switch on the bypass next week so it turns on when the bypass gets opened. The result is no more smoke in the boiler shed . The temps on the unit stay well within range. The second thing I did was lining the firebox with 1.25 " firebrick. My thoughts were that the wood was cooling of or not getting to the right temps for a good constant gasification. No I have no hard data, just observation and "gut feel" on this one. ( farmers science in other words ) I just installed 4 bricks on end on both sides and two on side on top of those. I skipped doing the back and front for time saving as I would have to cut bricks to fit. The tar in the steel has kept them in place for me for now. Observation so far: It took a bit longer to get the unit to temp, but it was very cold after being down for the day. Once the boiler got to temp the flame went really blue and stayed that way. When the wood bridged a bit, but kept the flame blue and going, a bit smaller than normal but it still made heat and no smoke or smell. Then 10 to 15 min later the bridge collapsed and the boiler was running full again and didn't bridge again. I have also found much less ashes and embers (or unburned coales) in the secondary chamber. This looks to me like a win,win situation and I added an other row of brick on top as the first bridge was hanging on the brick edge. Henk.