Page 29
990-WNWD-I03-020317
Evaporation
When you light the cooker a lot of energy will be needed at first to
boil away any moisture, which is left in the wood. Using energy to
drive off excess water in firewood robs the cooker of energy
needed for an efficient and clean burn. Also, much of the energy
wasted in evaporating water is energy that could have heated the
hot-plate and ovens. This is a waste of wood, money and effort. The
presence of all that moisture tends to keep "putting out" the fire,
and therefore making it burn very poorly, which tends to produce a
lot of creosote and pollution.
Emissions
As the heat of the fire intensifies, waste-gases (smoke) are released
from the wood.
Unburned smoke is emitted into the air either as pollution, or
condensed in the chimney causing creosote build-up. It takes time
for the air in your chimney to heat up. When it is still cold you get
an effect similar to the condensation of hot breath on a cold
window or mirror. So when the by-products of combustion (smoke
in the form of gases) exit the cooker, and flow up into the
relatively cooler chimney, condensation occurs.
The resulting residue that sticks to the inner walls of the chimney is
called creosote. Creosote is formed by unburned, flammable
particulates present in the smoke. It is black or brown in
appearance. It can be crusty and flaky, tar-like, drippy and sticky or
shiny and hardened. Quite often, all forms will occur in one
chimney system.
If the wood you are using is water logged, or green, the fire will
tend to smoulder and not warm the chimney sufficiently. Wet
wood causes the whole system to be cool, and inefficient. In
contrast: dry wood means a hot fire, which results in a hot flue. A
hot flue means much less creosote clogging up your chimney.
The cooker’s firebox is designed to operate at very high
temperatures to burn the gases and particles released from the
wood, which means less air-pollution.