On Thu, 1 Nov 2007 12:37:44 -0000 someone who may be "diy-newby"
Provided that the valves at both ends of the removed radiator are
turned off and watertight.
Count the number of turns on the regulating valve, so you can open
it to the same position when you replace the radiator.
If the control valve has a thermostatic head make sure it has a
decorator's cap fitted to ensure it stays shut.
When refilling have bowls and towels ready in case either valve is
not fully shut. Central heating valves do sometimes leak as they are
often operated infrequently.
In an earlier contribution to this discussion,
I would also make sure that the pipes to the disconnected radiator are full
of water, to reduce the risk of airlocks upstream which may affect other
rads. You can do this, once you've filled most of the system, by cracking
each valve open with a bowl under it until water rather than air comes out -
then shutting it again.