Have gas boiler manufactured by ferroli . Type optimax 25C.
looking for fault finder list as F03 showing. I need to know what F03 is to order part?

Fiona M Mitchell, October 2006

from the ferroli technical guys................

The usual cause of F3 is a blocked air separator tank which would need an engineer to check.

Gerwyn, January 2008

i have been informed by british gas that a power flush is required to fix this problem. i have a ferroli maxima 35c which is continually breaking down with this same problem. i am starting to think it may be a design problem

kevin toogood, November 2006

I'm also having same trouble with the same boiler.f03.According to the installation manual f03 is when the 100'c safety thermostat trips in.
Possible cause-flow sensor not active or correctly located or no system circulation.

cure-check the correct positioning and operation of the flow sensor.
check the pump.

i suspect the pump has failed,maybe due to being inoperative during summer months.possible seizure.will post again when i find the cause and let you know.ps.is yours making loud banging noises when hot water is demanded and not circulating central heating?

eric walker, October 2006

F3 is operation of the overheat thermostat. Make sure you have no air in the system and that the pump is running when required.

kenneth, October 2006