Viessmann VITOLIGNO 250-S Operating Instructions Manual page 48

Ordering fuel
Wood fuel ingredients
When procuring wood for combustion in a
Vitoligno 250-S, avoid wood containing foreign objects
(e.g. stones, metal parts, pieces of brick, plastics etc.).
These change the composition of the fuel and there-
fore the critical parameters of the combustion process.
Chlorine Cl
Sulphur S
Total Cl, S
Ash content total
Alkali oxides in the ash (K
SB (start of sintering) of ash
Exceeding the above limits will shorten the service life
of the combustion chamber and the solid fuel boiler.
This also means that the amount of maintenance work
increases and service intervals become shorter.
Influence of the moisture content
The rated boiler heating output is only achieved with
dry wood with maximum 20 % water content (air-dried
wood). Wood of poorer quality and higher moisture
content also reduces the rated heating output and the
length of combustion.
Storage and drying of wood
Wood requires 1 to 2.5 years to dry naturally and
reach a moisture content of 20 - 25 %.
Standard values for storage:
Storage period
Over a summer
Over several years
Information on storing firewood
Split all round logs from a diameter of 10 cm
■
upwards. Enlarging the surface area enables the
wood gases to escape more easily and quickly. This
also accelerates the drying process during storage.
■ Stack the split logs in a ventilated and preferably
sunny spot underneath a rain canopy.
Stack the split logs with generous gaps in-between.
■
This allows moisture to be dissipated by the air flow.
Approved logs
For combustion in the Vitoligno 250-S, the following
requirements apply for logs such as split or round logs:
48
mg/kg
mg/kg
mg/kg
g/kg
O and Na O) g/kg
2 2
°C
Moisture content of fuel
Approx. 30 % moisture content
Approx. 15 % moisture content
The values must not exceed or fall below the following
limits (per kg of dry fuel) for the non-combustible con-
tent (ash at an analysis temperature of 815 °C):
Limit
max. 300
max. 1000
max. 1000
max. 15.0
max. 1.0
min. 1000
The proportion of dust-like and fine-grained materials
should also be minimised (in accordance with
EN ISO 17225-4).
When using softwood (e.g. spruce), note that the
energy per volume unit is lower than with hardwood
(e.g. beech). Softwood is therefore well suited for initial
heat-up – however, the intervals between recharging
are considerably shorter and the volume required is
greater (up to 44 %).
Hardwood: 2 to 2.5 years
■
■ Softwood: 1 to 1.5 years
Provide a gap underneath the wood pile (e.g. by
■
using support timbers) to allow the moist air to
escape.
■ Never store freshly cut wood in a cellar, as air and
sunshine are required for drying. Once dried, the
wood can however be stored in a well ventilated cel-
lar.
Comparison with natural
wood from forests
120
130
0.35
approx. 1200
10
5.0