First time ever. Loaded the Tarm, did not latch the firebox door, draft fan "on." Came back an hour later and the shop was pretty full of smoke, firebox door was against the frame but not latched. This could have been a run away fire, but I have a K-type sensor in the flue connected to a temperature controller which shuts off the draft fan when flue temp reaches 450F. That thankfully kept the fire under control, no real damage done, aired out the shop, and all is back to normal. Fail safe controls are good. Whew!
