Install Instructions

6
4 Commissioning
4.1 Flushing and filling the solar thermal system
Observe the following safety instructions for commissioning the solar thermal system:
Attention: Risk of scalding
To prevent the solar fluid boiling in the collectors, the system should not
be flushed or filled during periods of strong sunshine.
Attention: Risk of freezing
Solar thermal systems cannot be completely emptied after flushing. There
is a danger of freeze damage if water is used for flushing. Only use solar
fluid to flush and fill the solar thermal system.
Use a water-propylene glycol mixture as a solar fluid (maximum 50%
propylene glycol).
The solar thermal system is flushed, filled and emptied via a flushing and filling unit.
Instructions for initial commissioning
If the flushing and filling unit is integrated in the solar station (see fig. 1) and if you are
commissioning the storage tank for the first time, we recommend an additional fill and drain ball
valve in the return at the lowest point of the solar thermal system, to flush possible scale out of
the storage tank. The flushing and filling station must have a filter that prevents the flushed-out
scale from re-entering the solar circuit. This flushing process is described in “5.2 Flushing the
storage tank for initial commissioning”. Then continue as described in “5.3 Flushing and filling
the solar thermal system”.
If the flushing and filling unit is not integrated in the solar station, and external flushing and filling
unit is required, see fig. 2.