84 www.eta.co.at
Judging the quality Information on fuel
Judging quality when buying by the kilogram
Criterion Comments
Effect on energy content
per kilogram
Water content The lower the water content, the higher the heating value. The
water content is given as a percentage of the total weight.
20%
30%
35%
40%
+12%
0%
-12%
-20%
Chip size The chip size has no effect on the heating value per kilogram
Kind of wood Heavy hardwood, when dried, has about 5%
less heating value than softwood, and about 6%
less when moist.
Light hardwood, when dried, has 6%
less heating value than softwood and 7% less when moist.
Softwood
Hardwood
0%
-5%
to
-7%
Bark content The bark content has little influence on the heating value per ki
logram, but a high bark content means a higher ash content an
d more time spent on cleaning.
Small branches Wood chips from small branches usually have a high degree of
decay.
Small branches -25%