Ravelli Sara Owners And Installation Manual - 3. What Are Wood Pellets?
4
Page 2
3. What are Wood Pellets?
Wood pellets are made from sawdust and wood shavings.
The material used cannot contain any foreign substance
such as glue, varnish or synthetic substances. Subjecting
it to high pressure, the wood is pressed through a plate
with holes and due to the high pressure the sawdust is
heated activating the natural binders of the wood. Thus,
the pellets keep their shape even without the addition of
bonding substances.
The density of the wood pellet varies according to the type
of wood and can be 1.5 – twice greater than that of natural
wood. The diameter of the cylindrical rods is 6-10 mm and
their length can vary between 10 and 50 mm. Their weight
is equal to about 650 kg/m.
Due to the low content of water (approx 8%) they have a
high energy content. The standards AS/NZS 4014.6 defi ne
the quality of the pellets.
Do not put the bag of pellets on any part of the fi re during
the loading operations - hot surfaces can melt pellet
packaging.
The pellets must be transported and stored in a dry
place. They swell on contact with damp, and cannot
be used, They must always be protected from the
damp both during transport and in storage.
Ravelli
recommends using a pellet with a diameter of 6 mm for
the stove.
4. Maintenance and Cleaning
4.1
Components of the Fire
This drawing shows the internal parts of a wood pellet fi re.
By fi lling the tank (7), the pellets are loaded into the fi re pot
(3) through the loading screw (1). Ignition is by means of
the resistance (2), which overheats the air from the special
intake (5) which on contact with the pellets will allow the
development of the fl ame. At this point the exhaust smoke
is deviated towards the stainless steel exchanger (6) and
through the smoke extraction tube (4) it is released into
the fl ue, through the connection with the smoke exhaust
pipe (9).
2
3
6
8
5
4
9
1
7
10
1. pellet feeding auger
2. igniter
3. burn pot
4. exhaust duct
5. combustion air inlet
6. heat exchanger (AIR
& BOX Models)
7. pellet hopper
8. fl ame trap
9. exhaust/fl ue outlet
10. exhaust fan
a low ash fuel may allow for longer intervals between
cleaning.
2.4 Clinkering
Clinkers are silica (sand) or other impurities in the fuel
that will form a hard mass during the burning process.
This hard mass will block the air fl ow through the Burn
Pot Liner and affect the performance of the stove.
Any fuel, even approved types, may clinker. Check
the Burn Pot Liner daily to ensure that the holes are
not blocked with clinkers (see above). If they become
blocked, remove the liner (when the unit is cold) and
clean/scrape clinkers out. Clean the holes with a small
pointed object if required. Refer to the section Routine
Cleaning and Maintenance.
Correct daily cleaning will allow the wood pellet fi re to
burn properly with high performance, avoiding problems
in the long-term which could require the intervention of a
technician to repair the wood pellet fi re.
Important: Even with a new batch of pellets,
although using the same brand, there may
be variations in the combustion process, and
therefore they may burn either more or less
cleanly.