Any tips for fitting valves?
Wrap at least five turns of PTFE tape around the threaded tails of the valves to help seal the joint between the tail and the radiator at the valve connection point. Make sure the PTFE tape is embedded into the thread (to secure it in place) before turning. If it is not secure it could run round and round in which case undo the valve and roughen the thread slightly with a hacksaw blade then re-tape the thread.