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?

This is best left to a registered gas installer, as those faults are concurrent with ignition faults.

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.

f4 is flame goes out whilst lit during a demand.

several possible causes for this.

if your guy cant read the manual then he isnt up to the job.
is he reading the user instructions?