2.4.6 Combination with storage tank
Always observe and abide by regionally binding regulations when using a storage
tank. Certain subsidy guidelines also prescribe compulsory requirements for the instal‐
lation of buffer storage tanks. Up-to-date information relating to specific subsidy guide‐
lines for your region can be found on our website www.froeling.com.
Combining the system with a buffer storage tank offers significant advantages when
using a firewood boiler, such as better utilisation of the fuel, more user-friendly opera‐
tion in terms of reloading intervals (which means the greatest possible independence
from instantaneous heating requirements), and less soiling of the boiler and flue gas
system. In addition to the above, as the manufacturer of the boiler we have to advise
on how the heat generated can be dissipated. This is because compliance with the
emissions limits and minimum levels of efficiency at a minimum heat output of max.
30% of the rated heat output, as specified in Section 4.2.5 of EN 303-5, has not been
demonstrated for all variants of the system.
The recommended storage volume for each boiler is given in the technical specifica‐
tions. The specified value applies under the following conditions: the rated heat output
of the boiler corresponds to the heating requirements of the building and a maximum
of 50% of the rated heat output can be dissipated to the building being heated under
partial load conditions.
Calculating the storage tank volume as per EN 303-5:
VSp
QN
TB
QH
Qmin
Storage tank capacity in [l]
Nominal output of the boiler in [kW]
Combustion period of the boiler in [h]
Heating load of building in [kW]
Minimum output of boiler in [kW] 1)
1.The boiler’s minimum output is the lowest value of the output range in the technical data. If there is no minimum output specified, use the
nominal output (Qmin = QN)
In accordance with the relevant Austrian laws governing energy technology, which are
based on Art. 15a B-VG "Agreement on protective measures for small furnaces" dated
November 1994, no buffer storage tank is required on manually fed biomass boilers
that have been positively tested at both nominal load and partial load (below 50% of
nominal load) to ensure they adhere to the emissions limits specified in that agree‐
ment.
The first BImSchV (Ordinance on small and medium-sized heating plants of 26 Janu‐
ary 2010, BGBl. I P. 38) stipulates a minimum water heat storage tank volume of 55
litres per kilowatt of rated heat output; a water heat storage tank with a volume of 12
litres per litre of fuel loading chamber is recommended.
For the correct dimensions of the storage tank and the line insulation
(e.g. in accordance with ÖNORM M 7510 or guideline UZ37) please consult your installer or
Froling.
General information
Austria
Germany
2Safety
Design Information
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