Thanks for the response.
I do have a registered gas installer looking at the system. However as it is an intermitten fault - and we can find no trace of the F4 fault in the manuals - he has asked me to look on the forum to see if anyone else has come across this problem.
I have the above-mentioned boiler which keeps cutting out and flashing the F1 and F4 faults. I have topped up the pressure. This is an intermittent fault - can anyone help?
