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Section 5 – Various types of fuel
5.3 Machine / industrial chips
Machine chips are made from waste wood from furniture production or the like. The
size of such chips vary from 2 – 3 cm up to 8 – 10 cm, and the thickness round 2- 10
mm. Only very seldom would you see bark in this kind of chips. The water content will
be round 10 % and they have a high heating value.
Machine chips have a tendency to create bridges in the fuel store, hence it is often an
advantage to connect the stirrer.
5.4 Grains
If you are heating by burning grains (e.g. rye, wheat or barley), the water content of the
fuel should always be under 15-16%.
One cannot for sure say, that one sort of grains is better than another, as the heating
value depends on the year the grain was grown ( much rain / little rain and more) and
of the type of soil, on which it was grown.
Further you should anticipate, that grains has a tendency to create slag in the burner
tube, e.g. the ashes gets so hot, that they create slag in the lower part of the burner
tube.
This can be remedied by adding 1 – 2 kg of feed chalk (calcium carbonate) on top of
the grains in a filled fuel store. The grains and the chalk will by it self be mixed. Further
the risk of slag can be reduced by mixing 33 % wood pellets into the grains
Should there be a layer of slag in the burner tube it must manually be removed by
using a fire hook.
PLEASE NOTE:
Requirements when heating with grains: High flue gas temperature min. 180°C
High boiler output min. 50%
High boiler temperature min. 80°C
