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Pressure test
Venting the system
3062165_201508
Pressure testing / Venting the system
Once the entire solar circuit including the collectors is filled with heat transfer
medium, the system must be thoroughly flushed (flow velocity > 0.4 m/s) to
ensure that all foreign bodies (scale, swarf, etc.) and air pockets are removed.
Experience suggests that the flushing should be maintained for at least
20 minutes in order to flush out all foreign bodies and air pockets.
The following procedure has proven reliable for the pressure test:
-
Fill the solar circuit (incl. collectors) with ANRO until the pressure reaches
90 % of the maximum system operating pressure (response pressure of
the safety valve minus 10 %).
-
Maintain this pressure for at least 30 minutes. (Note: Glycol mixtures respond
significantly slower to leaks than water.)
- Now conduct the leak check for all screwed fittings and soldered or
compression joints.
-
DEV and safety valve remain integrated during the pressure test.
If the pressure test is successful, first bleed the system and then discharge
ANRO until the pressure is reduced to the charge pressure of the system.
If the test shows leaks, drain the ANRO to a level at which the remedial work
can be carried out. Following this, repeat the pressure test.
During commissioning, ensure that the system is carefully vented. The ANRO
previously filled into the system usually still contains micro bubbles that may
collect at various points and form small air bubbles, for example in the pump,
in the heat exchanger or upstream of the gravity brake. Care must be taken to
remove these air bubbles.
Signs of adequate ventilation of the system are a steady indication of the
required flow rate and a steady pressure during pump operation, i.e. neither
the flow meter nor the pressure gauge show fluctuations.
After the first few weeks of operation, we recommend venting the system
again at all venting points to release any air that may have collected.
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