The pressure reads zero and the valve that usually repressurises the system does not work, almost as if it has an airlock. There is no sound of any water movement in the pipes at all.
Any ideas what the problem might be?

Gus MacKinnon, September 2007

Not sure about "the valve that pressurises the system". Do you mean the filling loop? Do you have a filling loop connected to main inlent and feed to system? To check it is working ok disconect the feed to system end and gently turn on the valve.....if water escapes, the loop and valve are ok

Philip Nugent, September 2007

faulty valve on the filling loop.
or another valve further down the pipe

hi-spec plumbing, September 2007