Header overflow - should be so simple.

[Ric2013]

That wasn't how I meant you to feel, so apologies if that's how I've come across.
All I meant was that that I thought your comment suggested that you'd only just seen the bit about the one-way valves not being one way and the isolator not isolating and hence the thread was becoming 'stranger and stranger' and I wondered if you'd read the thread in its entirity.

 

[rpm]

I've followed it from the start, perhaps not fully understanding it all but none the less puzzled considering all the valves in place and their functions. Well aware of strong and weak non return valves I might add.