Radiator valve replacement and piping alteration

[superspark]

Can someone please advise me on the following problem?
I have a Worcester CD30 SYSTEM boiler which is connected to the plumbing in an S configuration. Heating is pumped and hot water is pumped via 2 diverter valves. There is a radiator in the upstairs en suite which is part of the hot water circuit ie the radiator does not heat when central heating is on but does work when domestic hot water is on.
I have removed this radiator to fix new tiles behind it and to fit a ladder type radiator therefore I need to take off these closed valves and replace them and modify the pipework. Do I need to empty the whole system to do this or can I get away with emptying part of it?
You help would be much appreciated,
Thank you very much...

 

[SimonG]

Depends how skilled you are.

On a system boiler I wouldn't drain down. But you may find it easier to drain down, gives you time if things dont go to plan

 

[king of pipes]

Drain down it's safer all round

 

[superspark]

Thank you very much for your replies.
If I do drain down would it drain down both circiuts and where would the drain point be?
The system has fernox which would obviously have to be replaced if drained down fully so I would prefer not to do so if possible.

Thank you...

 

[king of pipes]

Hmmm it like this bud I wouldn't change me own fuse board why ??? Because I'm not compent and I'd probably do something wrong , it's like this you can change my fuse board because your compent and know what your doing you will struggle with the plumbing if you cant isolate and drain down safely fact ! as for loosing ya fernox it needs draining and replacing every 5 years anyway my advice get a plumber in chill, relax, have a beer take the dog for a walk be done in a few hours . Kop