"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