Thermostatic regulating valves

[Timlouth]

I am changing a radiator.
I know I can isolate both sides with the stop valves to remove it but can I change the discharge valve to a thermostatically controlled one without draining the whole system down.

Many thanks

Tim

 

[Blasphemous]

What type of system do you have? Combi, Open Vented etc?

 

[Timlouth]

Pardon me for being a dumbass but I am not totally sure.
I am an electrician and only moved in to the house two weeks ago. Up to now I have been all electric.
I do know that I don,t have a combi boiler and the system I have got is ten years old and no longer allowed to be istalled as it is not environmentally friendly or economical. I will be getting a new boiler next year.
The central heating pump is fitted in the boiler, which is a Glowworm Hideway.

Cheers

Tim