Installation instructions
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6.2 - FIREWOOD
Wood is formed mainly by cellulose and lignite.
It also contains other substances, such as resin
(fir - pine), tannin (oak - chestnut) and, obviously, a
large quantity of water.
Good quality woods are oak, ash, beech, maple
and fruit trees, except cherry; medium quality wood
is: chestnut and birch; sufficient quality wood: lime
tree, poplar and willow.
Resinous trees are, normally, second-rate quality fuels.
Wood is therefore an extremely heterogeneous fuel, due to
different essences (beech, oak, fruit, resinous), different moisture
content, and due to different shapes and dimensions.
Boiler operation will inevitably be effected by all these factors.
Especially by the log dimensions, the moisture content and the
way wood is loaded in the boiler.
6.3 - WOOD MOISTURE
The calorific value of the different types of wood
depends on their moisture content.
Boiler output and autonomy will diminish as the
moisture increases.
The heat output of the AIREX boiler is calculated
for wood with a 15% moisture content.
6.4 - FIREWOOD DIMENSIONS
The dimensions, together with the moisture content,
contribute to determine the boiler’s output. Small
pieces (with a length, however, conforming to
indications indicated hereby) are more easily
flammable and therefore have the tendency to
increase the boiler’s output and therefore to reduce
its autonomy. Moreover, they fall with greater facility,
in the lower chamber, reducing the risk of the
formation of “bridges”. The so-called “bridge” is an
empty space in the firewood storage compartment, where
unburnt wood logs remain. In this case the bed of embers is not
fed with continuity and the refractory burner’s slot is
uncovered. In these conditions, preferential air passages are
created with a very small flame due to an excess of air.
The AIREX boiler must be fed with natural wood logs at the
length indicated in paragraph 6.6.
The logs must normally be round (Ø approximately 10 cm).
6.5 - INITIAL LIGHTING
CHECKS
GENERAL CONTROLS
At the first ignition: check that the C.H. system has
been properly filled and properly purged, that the
safety heat exchanger is connected to the water
mains via the thermal safety discharge (fig. 10,
page 15 and fig. 18 page 20), that the chimney has
a sufficient draught, that the electrical
connections have been made correctly (chap. 4)
and that the recirculation and boiler pumps are not
blocked.
Furthermore check that the stainless steel grates
and the fire bar are positioned properly.
THE BYPASS
The bypass is a direct passage between the firewood storage
and the chimney. It is normally closed by a mobile shutter.
The bypass is automatically opened or closed via a pushing rod
when the loading door is opened.
In this way the smoke accumulated in the wood storage is
suctioned and sent to the chimney directly.
The bypass, in conclusion, allows the smoke to be discharged
to the chimney without escaping from the loading door when
loading the wood or during lighting.
Anyway, it is essential to open the loading door slowly and, as
well, to rotate the antismoke flap (pos. 3, fig. 2) gradually so that
the smoke is effectively suctioned.
BYPASS CONTROL
During the installation stage and, in any case, before starting
to use the boiler, check the tightness and then the operation of
the bypass.
Make sure the bypass rod works and that the microswitch is
positioned correctly. Check that the fan starts up as soon as the
door opens. If needed, adjust the control plate of the
microswitch.
As an example, wood which has been dried for 2 years in a
sheltered area has a 25% moisture
content.
Use only wood with a moisture content between 13 and 20%.
