Corrosion on pipe connections.

[king of pipes]

I would be contacting the manufactures of the solar cylinder for their input is there a sacrificial zinc/Aluminium anode installed ? In the unit ? if this has failed then it could be the cause,?.. kop

 

[Ric2013]

This has already been answered?

Not really. You said they don't tend to use inhibitor so you assumed it's just water. Glycol is a kind of antifreeze that also raises the boiling point so non-use of inhibitor isn't a reason to assume non-use of glycol.