Thanks for that posting, i didn't look for a search i must admit.
I have found the problem, i put the pump in the wrong way up.. how stupid do i feel now?
Thanks for all your help guys
Rob
I wonder if you can help me, i have just fitted a new pump due to the old one being noisy. Since i have done this there is no heat upstairs, i have checked that i have opened all the valves. I have also checked that the header tank is full and the new pump is working. All seems to be ok so far...