shower valve swap

[lockwise123]

hi
many years ago i put in a mira 88 exposed valve (used in conjunction with my old back boiler setup) - recently i had a combi boiler installed and the mira 88 is not great but it seems mira 415 is best suited to a combi boiler setup.

anyway, thats neither here nor there. In order to remove old 88 unit i of course have to switch off water to it. Alas although the cold feed to the mira has it's own stop valve, the hot pipe to it doesnt.

So is it ok to turn off the cold water at the mains then drain shower until water flow stops? But more importantly, when i turn on the mains supply again do I need to do anything to the boiler or will the water find it's own way thru it etc?
thanks

 

[lockwise123]

not a single plumber knows?

please

 

[havasu]

Just guessing here, but because you are in the UK, and most of the plumbers are from the United States, the plumbers are not trained for the systems in other parts of the world. Stay tuned, as I am sure someone will help you.

 

[frodo]

as you can see, the potable cold water has a valve before the water heater, turn it off and it will turn off the water on the potable hot system as well.

I am not familiar with your terminology i hope this attempt at a drawing helps make it clear