Maybe the pressure valve is faulty - but I'm not sure that would explain the lack of water emerging from anywhere, pump running.  It must either go over the side (valve open) or through the membranes and into the tank (valve closed), mustn't it? It certainly was not leaking out anywhere else (which I presume would be quite dramatic to witness, at high pressure...). 

Bill, I should have discussed this with you in Malta - I could have seen your whizzy automatic flushing system too. 

Elsewhere in the forum I have seen angry comments about the 'quality' light (which is far from having relevance to me, sadly) - and on reviewing the Desallator manual I see that 'the biggest enemy of the membranes is fresh water' whilst in the Amel owners' manual we are instructed to flush with fresh water after use, and your system seems to be doing that.  Does the carbon filter remove chlorine, which I read is also an enemy of the membranes (which seem to have few friends)?

PS - my system is the 60l/hr one - no low-pressure pump, 'detuned' CAT pump. 

Keith

GUMA (SM 261)