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24
Chapter 3
DIMENSIONING
PRODUCTION OF HOT WATER AND INTEGRATION TO HEATING
The dimensioning of the solar system combined for the production of domestic hot water and integration
with heating is much more complex with respect to that just for the production of hot water and must
always be supported by a dedicated calculation and simulation program. Large over-dimensioning of the
system must only be carried out when there is large consumption of water in the summer period, the
presence of a swimming pool to heat and the possibility to install the collectors with high inclination. It
can be deduced from the fi gure below that great covering of the heating requirement inevitably leads
to an intake of the solar system in the summer period. It is for this reason that the solar system is usually
dimensioned to cover 30% of the requirement for heating at a maximum.
A general indication can be obtained starting from the consumption of domestic hot water and calculating
the surface of the collectors necessary. This value can be doubled or tripled on the basis of the inclination
with which the collectors are installed. Only in the case of installation with inclination exceeding 70° or
the presence of a swimming pool allows the installation of 1.5 – 3 m
2
of collector every kW required by
the building for heating. The table summarises the indications for the dimensioning of a combi system.
Remember that the fact that the exact calculation of the collector surface necessary must be carried out
by an expert heating technician, supported by a calculation program.
Also in this case the volume of the storage tank necessary is equal to 70 litres every m
2
of collectors
installed.
Useful intake of the
solar system
Requirement for
domestic hot water
Requirement for
heating
kWh/(m
2
M
o
nth)
Inclination of the collector
Reference values for the dimensioning of
the collectors
<40°
Surface just for hot water in m
2
x 2
>40° e <70°
Surface just for hot water in m
2
x 3
>70° and <90° or integration of the swimming pool
1,5 – 3 m
2
/kW
fi gure 3.4