In an earlier contribution to this discussion,
John wrote:

"wounded horse" wrote in message
...
I have to change a friends kitchen sink and taps which looks
manageable enough but I note that the water/heating is an unvented
cylinder with expansion and pressure safety devices aplenty. I know
the system delivers hot water at cold mains pressure but how do I
shut off the hot supply so I can disconnect the tap(s). Does
turning off the Cold main isolate the hot supply as in combi boiler?

yes but you may find the stored pressure takes some time to run down

And you may have to re-establish the air bubble when you've finished - for
which there should be some instructions on the hot cylinder.

If you're *very* lucky, there may be isolator valves on the pipework under
the sink. If you can turn these off, and just disconnect the pipework on the
tap side of the valves, you won't have to worry about the pressurised
system.
--
Cheers,
Set Square
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