Wood Heaters, page-139

Flue fires aren't particularly dramatic from what I've seen. I recall my grandfather's flue catching fire when I was a teenager and other than some sparks flying out the top of the chimney you wouldn't have known it was alight. We also caught our flueless chimney(old brick chimney in an old farmhouse) numerous times and we'd just shut the air intake to the firebox and wait till it went out .. again the only clue was sparks flying out the top - we actually got a call one night from a neighbour up the road to tell us the chimney was on fire