I changed two last year after 1 split and one looked as if it was about to. It depends if youhave a header tank or a pressurised system. Luckily I have a header tank.
Its quite easy, but a bit slow.
First find the bottom drainage point and place a large bowl underneath it. Switch off the mains (so the header tank doesn't keep filling up) then slacken off the bleed screw. Keep going until no more water comes out - it will be black and horrible if its an old system)
When you have drained it, you can slacken off both valves from the rad and then remove completely. I would suggest puttin gold towls underneath to catch the drips.
Once the valves are off, you can then lift and take the rad off the mounting brackets. Have a bowl nearby to pour the remaining water out the rad into before you carry it out.
Refit is simply mount it in the bracket, do the valves back up with some PTFE tape then turn the bleed screw back closed. You can turn on your mains and the header tank will refill. Slowly allow the system to fill, using the top bleed screws on the rads to bleed the air and fill the rads. Its easier to have the system "on" and the pump going when your refill the system.
I hope that was of some help
alfa"DIY"nige
Yes I am bored
