1. As HE says use the decorators cap which should have been supplied with the TRV. Just remove the thermostatic head and screw the cap onto the valve so that the "pin" of the valve is held shut mechanically. You can then drain the rad and remove.
2. Crack the large nuts which connect the valves to the rad tails. Lift the rad off the brackets and rotate downwards so that the top rests on the floor and the bottom remains connected to the pipework. Place some support under th bottom to avoid stressing the pipes and connections. Re-tighten the large nuts to prevent water escaping. Decorate and reverse process. This one only works where there is sufficient play in the pipework run beneath a wooden floor to allow you to lift the rad off the brackets. This one works well with open vented systems. With pressurised systems you must take the pressure off the system first. Otherwise it pours out of the connections when you crack the nuts.
Edited to correct spelling.
Last edited by rosebery on Wed Mar 11, 2009 6:53 am, edited 2 times in total.