G
Gibberz
Right, open the red valve immediately under it fully until you can hear no more water then release it and let itself snap shut, Open the black valve on the end of the flexi and refill to about 1.0 bar.
I'd say he dumped the water pressure there and you may have a bit of crap on the safety valve seat. you should be able to flush it free.
Many thanks for the reply. When the plumber recharged he filled some air with a foot pedal. Would I not need to do that too? I don't have one so would have to try and get the plumber to come back tomorrow