Turn off both valves on radiator - Loosen big nuts (the ones that screw to the radiator) and let water drain out - I catch it in a paint-roller tray and use a small jug to tip into a bucket. When drained lift rad off wall. Will drain quicker if open bleed screw on top to let the air in - do this AFTER you have turned off valves - not before.
Expect dirty black water at end of draining process. Put down something to protect floor. Cover inlet and outlet holes with clingfilm to stop black sludge coming out - carry rad upside down if passing over unprotected floors.
Peccavi, October 2008
