Soot is unburned carbon that settles on tubes, flue passages and baffles. It insulates the heat transfer surface, so stack temperature climbs and efficiency drops, and it can plug flue passages until draft fails and the burner spills or rumbles. A sooted-up boiler needs both a cleaning and a fix for the combustion problem that caused it, or it soots again within weeks.
Boiler's completely sooted up, flue passages are half closed, you'll need the vacuum and brushes and then figure out why it was smoking.
Also heard as
- sooted
Related terms
Running rich
Burning with too much fuel for the air available, so combustion is incomplete.
Smoke spot
An oil burner test that pulls flue gas through filter paper and grades the dark spot from 0 to 9.
Punch the tubes
To clean soot from firetube boiler tubes by running a brush on a long rod through each one.
Stack temperature
The temperature of the flue gas as it leaves the boiler, a direct measure of how much heat is going up the chimney.