FireBird Bio-Tec Manual page 6

How does wood burn ?
There are essentially 3 stages involved in burning wood...
I. When the wood is first heated most of the energy is used to
remove the moisture from it
II. As the wood heats up (100ºC to 300ºC) it starts to smoke.
Smoke is a cloud of combustible gases (CO2, CO, H, CxHy,
etc.) and tar droplets
– Smoke will burn if the temperature is high enough and enough
combustion air is supplied.
– If the smoke does not burn it will flow into the chimney where it will
either condense as creosote or go outside as air pollution (waste)
III. As the fire progresses and most of the gases and tars have
vaporized out of the wood and charcoal remains. Charcoal is
almost 100% carbon and burns with a red glow and very little
flame or smoke