A rich burner shows low O2, rising CO, a lazy yellow flame and eventually soot. Causes include high gas pressure, a slipped linkage, a dirty fan wheel, a blocked air intake or a hot-day drop in air density. The opposite, running lean, wastes heat with excess air and can make flames lift off the burner. Rich is the more dangerous side, because CO builds quickly.
It's running rich at low fire, 0.8 O2 and the CO's climbing, open up the air on the first cam screw.
Also heard as
- rich
- fuel rich
Related terms
Excess air
Combustion air supplied beyond the exact amount needed to burn all the fuel, expressed as a percentage.
Air-free CO
Carbon monoxide in flue gas corrected to zero excess oxygen, so dilution with air cannot hide a CO problem.
Lazy flame
A long, soft, yellowish flame that drifts and licks the furnace walls instead of burning crisp and compact.
Sooted up
Coated with soot on the fire side, from rich or poor combustion, so heat transfer and draft suffer.