replace thermostatic mixer shower valve (mains pressure unvented system boiler system)

[Topslice]

With a thermostatic mixer showers, can you replace
the unit, in a mains pressure unvented system boiler
configuration, by just turning the cold mains off
at the stopcock when the water supply enters the
property? Will the hot and cold water stop flowing
if you turn the mains water off?

 

[SimonG]

Yes.

Careful you dont create a vacuum on the hot water though and implode the cylinder. Very unlikely but can happen.

 

[Topslice]

Yes.

Careful you dont create a vacuum on the hot water though and implode the cylinder. Very unlikely but can happen.

Thanks - what do I need to do or not do so as not to create a vacuum in the cylinder?