7
2008-03
Vedolux 37
Checks
After installation, check with the installer that the system is in perfect
condition.
Ask the installer to demonstrate the settings and functions so you know
how to operate and care for the system.
Checks
Before putting the system into operation, check that:
•
the system is filled with water
•
all connections are watertight
•
flue gas connections to the boiler and to the chimney are tight
•
the filling/drain valve has been closed properly.
•
the safety valves are working correctly
•
the necessary valves are open
•
the circulation pump is working and the direction of flow is cor-
rect
•
the correct temperature has been set on the charge thermostat
Firewood as a fuel
Vedolux 37 has a ceramic grate and an afterburning chamber
made of high-temperature resistant stainless steel. The boiler
works on the principle of reverse combustion. If the boiler is
correctly operated, it burns firewood and gases very effectively,
with high efficiency and low environmental impact.
Using firewood as a fuel is not simply about burning the wood –
the techniques used have a decisive effect on the result.
Firewood
Hardwoods generally have a higher energy content than coni-
fers. However, the most important thing is that the wood must
be dry – moisture content 12-30 %.
If the wood is damp, much of the energy is wasted on drying it
out, combustion is impaired and the risk of tarring increases.
Because of the high acidity of oak wood, it should not be used
as a fuel for extended periods. Oak should be seasoned for
more than three years before it is burned.
The blocks of wood must be the correct size for the combustion
chamber, around 50 cm long and around 15 cm wide, allowing
three blocks to fit the width of the grate.
To allow the wood to dry out, the tree should be felled at least
one season in advance. An alternative method is to fell the tree
in spring just after the leaves have come out, then wait a few
weeks before trimming and splitting the wood. During these
weeks, the leaves wilt and draw out the moisture. After another
few weeks of drying, the wood has 25-30 % moisture content.
After cutting, the wood must be split. The more it is split, the
faster and easier it will dry. If logs are difficult to split, the bark
can be stripped to speed up drying. Fresh wood is easiest to
split.
The wood should not be in direct contact with the ground, as
this causes the wood to take on moisture instead of drying out.
Ideally the wood should be kept under a roof but in a place
where the sun and wind can help dry it. The best place for fi
-
nal drying is the boiler room, for 2-3 weeks before the wood is
used. The moisture content after drying is around 20 %.
Firewood
Heat content
The heat content is the amount of heat that can be extracted
by the boiler and transferred to the boiler water. Heat content
should not be confused with energy content, which increases
with the size of the block of wood. The heat content increases
with the dryness of the block of wood, because less heat is
wasted on drying the wood.
Newly cut wood has a moisture content of around 55 %. Fire-
wood that has been dried out following our instructions has
around 20 % moisture.
The chart illustrates how the heat content changes.
If a building uses 25 m
3
of newly cut firewood (55 % moisture),
around 14 m
3
of water needs to be dried through the chimney.
In other words, the energy needed to vaporise 14 m
3
is wasted.
Other problems using damp wood include poor combustion
and dirty emissions, which in turn impair efficiency.
First burning cycle
In the first burning cycle, or if the boiler has not been used for a
while, it is important to just light a small fire. The ceramic parts
of the boiler may contain moisture, which must be vaporised
slowly so as not to crack the ceramic. Once the ceramic parts
are dry, you can light a full-size fire. The ceramic does not take
on moisture when the boiler is being used. See also the section
on “Operation and care”.
Moisture
content
