Herz pelletfire 20/20, Operating Instructions Manual, Page: 7 / 100

Fuels 3
7
3 FUELS
The HERZ pelletfire boiler should be operated
with the fuels and their properties which are
described in this chapter.
3.1 Log wood
The HERZ
– pelletfire is suitable for burning logs
to operate central heating systems for closed hot
water installations. Smaller split logs enable
higher boiler performance than whole ones. We
recommend triangular firewood with side lengths
of 50 cm and edge lengths of 8 cm. Too coarse or
too long firewood may lead to reduced
performance and hollow fire. The heat value of the
wood is primarily dependent on its moisture
content. The heat value decreases with increased
moisture. The combustion of wood with high
moisture content also causes a decrease in the
degree of efficiency of the boiler.
Wood should therefore be stored for at least two
years in a dry, ventilated place. Oak needs to be
stored for about a year longer. Dry bark displays a
heat value similar to wood but there is more likely
to be increased formation of ash.
The burning of unsuitable fuels could lead to
uncontrolled
combustion. The guarantee
becomes invalid! Operational faults and
consequential damage are likely to occur.
Possible consequential damage:
◼
Damage to the thermodynamic combustion
chamber, the lambda probe, the flue gas
probe due to aggressive residues in the
boiler
◼
Sooting or corrosion in the filling area due to
condensation as a result of using fuel that is
too moist.
◼
The escape of flue gas from the airflow
apertures through uncontrolled combustion
(deflagrations).
Combustion time at nominal load:
Combustion time in hours
Type FS 18 FS 20 FS 30 FS 40
Softwood 5 6,5 6 3,5
Hardwood 6 8 7 4,5
Wood
chips
3 4 3,5 2,5
3.2 Wood pellets
Wood pellets for non-industrial use according to
ENplus,
Swisspellet, DINplus resp. pellets
according to EN 17225 with following
specifications:
◼
Property class A1
◼
The maximum permissible fines content in
the fuel storage room must not exceed
8 % of the fuel volume (determined using
a perforated screen with holes 5 mm in
diameter)!
◼
Fines content at loading: < 1.0 m-%
◼
Calorific value at as-delivered condition
> 4,6 kWh/kg
◼
Bulk density (BD) at as-delivered
condition > 600 kg/m³
◼
Mechanical Strength (DU), EN 15210-1 at
as-delivered condition in m-
%: DU 97,5 ≥
97,5
◼
Diameter 6 mm
The nominal power and the emission values can
be guaranteed up to a maximum water content of
25 % and a minimum calorific value of 3,5 kWh/kg
of the permissible fuel.
From a water content of about 25 % and a
calorific value < 3,5 kWh/kg a reduced output is
expected.
Prevent the entering of debris such as stones
or metal particles into the system! Sand and
soil lead to higher level of ash and slagging
precipitation.
There may be a formation of slag according to the
fuel quality, which has to be removed by hand.
In the case of non-compliance, any warranty
or guarantee will be rendered null and void.
The burning of unsuitable fuels could lead to
uncontrolled combustion. Operational faults
and consequential damage are likely to occur.
If a different fuel is named explicitly on the order
respectively the order confirmation, the system
can be operated with the mentioned fuel.
Note: The system is set to the agreed fuel at the
commissioning. This setting (ID-fan speed, fuel,
flow and backflow, cycle times, etc.) should not be
changed when using constant fuel quality.
3.3 Suitable fuels
The firewood must be air dried, that is, dried at
least one year with water content below 20 %
preferable half-meter logs with an average
diameter of 10 cm. If the cleavage planes of the