As you can see from the photo[attachment=0]IMG_0197.JPG[/attachment] its leaking from what I believe is called the Gland nut.. The 22mm pipe feeds the hot water tank via loft cold tank so that will have to be drained down then reduce level of water in the hot water tank to take all water out of feed pipe;.
Two thoughts.on self repair if job too small for plumber.
1. Holding the large back nut can I undo the gland nut and repack it?
Or
2. Would it make sense to replace the valve [u]centre[/u] saves removing the body part which would mean top half of the pipe being disconnected from the cold water tank in the loft as there will be no movement in the pipe otherwise.
Have done this on 15mm stopcocks before. Hopefull the Plumbbase has same type and know I will have to buy the whole valve then remove centre.
Pain in the proverbia we were on last legs of holiday and son in law had to change the cold water tank it developed a leak (cira 1978) fortunate daughter discovered it before any damage could be done..
Hopefully this makes sense.
Thanks in anticipation..