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18.6 Backfire.
If you have been very unlucky and
the thermal valve has been triggered, it is necessary to clear out the
screw for moist pellets before re-starting the plant.
The easiest way is to dismount the 4 bolts holding the gear motor, and then twist it loose. Ask an assistant
to press the Start button while you hold on to the motor, and the motor will then quietly unscrew from the
screw tube, it may now be cleaned and finally gear-motor and screw can be re-mounted.
By repeated backfires, the pause times should be adjusted, see section 6.4.
Also check if a draught stabilizer has in fact been mounted in the chimney, this is very important with a
view to avoiding a backfire..
18.7 Clinker.
Clinker may build up in the area where the screw tube enters into the burner head, this may contribute to
the problems with the screw getting stuck. The fuel heaps up and is squeezed together so hard that the
screw cannot push it out.
In that case, clean the screw tube in all corners to get rid of any caked clinker in order to make the screw
run freely again.
A too ample formation of clinker by grain combustion may be reduced by adding about 1-2 % of calcium,
as mentioned earlier.
18.8 Bothering smoke.
In case of bothering smoke in the tank, or if smoke comes from the inspection door when opened, this
means that the boiler or the smoke fan needs cleaning.
18.9 Condensed water in flue gas outlet.
If condensed water occurs from the flue gas ducts, these should be insulated as this will otherwise lead to
corrosion and reduce the life of both boiler and flue gas ducts.
Moreover, it is recommended to raise the set temperature as this contributes to avoid the condensing.
The above-mentioned draught stabiliser also adds to ensure a healthy chimney seeing that fresh air will
constantly be drawn through the chimney, helping to keep it dry.
Also, heating with firewood will easily result in condense water if the heat consumption is very limited
indeed.
A very poor combustion can also produce a lot of condense.