3 | Design Information
16
M1820921_en | Installation instructions Dual fuel boiler SP Dual compact
3.8 Storage tank
Observe the regional regulations for using a storage tank!
Certain subsidy guidelines prescribe compulsory requirements for the installation of
storage tanks. Up-to-date information about individual subsidy guidelines can be found at
.
Channelling the heat generated by the Dual fuel boiler to a storage tank can bring major
advantages, such as
▪ better utilisation of fuel
▪ more user-friendly operation in terms of reloading intervals
▪ maximum independence from instantaneous heating requirements
▪ minimal dirt in boiler and flue gas system
As the boiler’s minimum continuous heat output is 30% above the nominal heat output,
we as boiler manufacturer are obliged under EN 303-5:2012, Section 4.4.6 to advise that
the Dual fuel boiler SP Dual compact must always be connected to a storage tank with
adequate storage capacity.
Certain countries have recommended storage capacities; these are listed below. The
specified values apply when the nominal heat output of the boiler corresponds to the
heating requirements of the building and a maximum of 50% of the nominal heat output
can be dissipated to the building being heated under partial load conditions.
The storage tank capacity can be calculated according to EN 303-5:2012 using the
following formula:
V
Sp
= 15T
B
x Q
N
(1 - 0.3 x Q
H
/Q
min
)
V
Sp
Q
N
T
B
Q
H
Q
min
Storage tank capacity in [l]
Nominal heat output of boiler in [kW]
Burn-off period of boiler in [h]
1)
Heating load of building in [kW]
Minimum heat output of boiler in [kW]
2)
1. Sample combustion times for various fuels are provided in the technical data
2. The boiler’s minimum output is the lowest value of the output range in the technical data. If there is no minimum heat output specified, use the
nominal heat output (Q
min
= Q
N
)
For the correct dimensions of the storage tank and the line insulation (for instance to
ÖNORM M 7510 or guideline UZ37) please consult your installer or Fröling.
Recommended storage tank capacity:
Unit
SP Dual compact 15
SP Dual compact 20
Recommended storage tank capacity
1)
[l]
1000
1250
1. Values for calculating the capacity can be found in the technical data or the technical data with partial load inspection (if available)
The exact design of the storage tank capacity is in accordance with the locally applicable
guidelines and regulations:
Austria
According to the relevant Austrian laws governing energy technology, which are based on
Art. 15a B-VG "Agreement on protective measures for small furnaces" (2012):
No 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 agreement.
