There should be nothing that has the ability to restrict or remove the access from the cylinder to the EV or any of the other safety devices on an unvented system. That would include isolation valves.
Exactly!
So any earlier comment to the contrary was incorrect.
And if the PRV has been correctly fitted on the cylinder side of a pressure reducing valve then that would protect the cylinder from over pressure as would the T & P release valve near the top as well.
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