Hi, I've just watched a video online on how to add inhibitor to central heating. I know I've got to turn off both valves at bottom of towel rail first. I did the left hand one easily, but I'm struggling with the right hand one. The one on the left had a cap which came off easily and I then turned off the valve which was underneath. The left hand one is very different though. It's much longer and just turns round and round when you try to remove the cap, so I can't access the valve. Does anyone know how I can access the right hand valve? Thanks.