The Chemistry Of Wood; Contribution To Environmental Protection; Evaluating The Combustion Quality; Wood Moisture Content And Calorific Value - HASE Lisboa Mode D'emploi

or gels is not permitted.
Combustion of the materials listed above not only gives off unpleasant odours, but also
generates emissions that damage the environment and are harmful to health.
16. The Chemistry of Wood
Wood predominantly consists of the elements carbon, hydrogen and oxygen. It contains
virtually no environmentally hazardous substances such as sulphur, chloride and heavy
metals. As a result, complete wood combustion produces mainly carbon dioxide and water
vapour as the primary gaseous products as well as a small quantity of wood ash as the solid
combustion residue. On the other hand, incomplete combustion can generate a number
of pollutant substances, such as carbon monoxide (toxic), acetic acid, phenols, methanol
(toxic), formaldehyde, soot and tar.
17. Contribution to Environmental Protection
Whether your Lisboa burns in an environmentally-friendly or environmentally hazardous
manner depends to a large extent on how you operate it and the type of fuel you use (see
„The Right Fuel").
Use only dry wood; hardwoods such as birch and beech are most suitable
Only use small pieces of wood to light the fire. They burn faster than large logs
and thus the temperature required for complete combustion is reached more
quickly.
For continual heating, adding smaller quantities of wood more frequently is more
efficient and more ecological.
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18. Evaluating the Combustion Quality
The following characteristics can facilitate easy evaluation of the combustion quality:
- Colour and composition of the ash
If the combustion process is efficient, the result is a fine white ash. Dark colouration
indicates that the ash contains charcoal residue; in this case, the burn-off phase was
incomplete.
- The colour of the flue gases emitted at the chimney pot
In this respect, the following applies: the more invisible the flue gases exiting the chim-
ney, the better the combustion quality.
During the transitional seasons (spring/autumn), outdoor temperatures above
16°C can impair the chimney draught. If a draught cannot be created at these
temperatures by rapidly burning paper or thin wood shavings (quick fire), you
should refrain from lighting the stove.
19. Wood Moisture Content and Calorific Value
Rule of thumb: the more damp the wood, the lower the calorific value
The calorific value of the wood depends largely on the wood moisture content. The more
moisture the wood contains, the more energy expended to evaporate it during the combu-
stion phase; this energy is then lost. Thus, the more damp the wood, the lower its calorific
value. An example: freshly cut wood has a moisture content of approx. 50% and a calorific
value of around 2.3 kWh/kg; in contrast, wood which has been efficiently air-dried has a
moisture content of approx. 15% and a calorific value of around 4.3 kWh/kg.
Accordingly, if you burn very moist wood, you will have about half the thermal output with
the same quantity of wood. Furthermore, burning moist wood results in substantial soot
build-up on the fire box window. Moreover, when moist wood is burned, the resulting water