Thanks SammyInnit - much appreciated - I thought using the plumber who'd fitted it 10 years ago (long before I bought the house) would make it easier to get sorted but I'll try a different guy who've I've used a lot in the past.
thanks again for your help.
Cheers
Ian
Hi SammyInnit - plumber has flushed the system but not power flushed it - afraid I don't know re inhibitor.
I read on a separate post that the pump might need replacing.
It all seems a bit trial and error though.
It will soon be like Trigger's brush - I'm up to £600 a counting and it's not fixed
I moved into a new house last May (2018) our Glowworm Ultracom 30sxi (F9 issue) has become the bane of my life!
Boiler is 10 years old - the plumber (who originally fitted the boiler) has 1/ cleaned pipes (boiler ok for 3 or 4 weeks then starts progressively F9'ing until it'll barely stay on)...