@PlumbCbp@vaillantuk Sorry mate just see this. Itโs a small care home on 3 floors, unvented cylinder and system boiler each floor.
Itโs a nightmare because their all still living there.
Donโt get confused: deaerators & AAVs are 2 different things. AAVs canโt remove microbubbles โ the main culprit causing corrosion & sludge!