Hi,
I have a Ferroli Optimax He 31C Combi gas boiler. In the morning it regularly locks out on a F03 code every time I run a bath. I then reset the boiler and it works ok again, until the next time.
No problem in the evenings!
Central heating all ok and no problems. It's only when I use hot water - but not all of the time! Anyone with any experience of this fault with this particular boiler?
Many thanks,
Frustrated,

Paddy M, December 2010

I am having this exact same problem. It is 9 months old too. I am not too impressed and wonder if anyone finally got a resolve and could share it with me please

James, October 2011

Hi, I brought a brand new house with athis type of boiler in it, it is absolutely terrible, it has broken down three times, the engineer is blaming the installers, the installers say they installed it correctly, leaving me with a bill for a new boiler, dont ever buy from Ferrloli

john, February 2011

have the same problem here,apparantly the water gets heated too hot so the boiler trips out to save you getting scolded,why the water temp stat does not prevent this happening god only knows

karl, January 2011

Many thanks Rob.
Really appreciate the time and effort that you have taken to reply.

Paddy, December 2010

Hi Paddy,according to the fault code list the problem could be one of two things,either the flow temperature sensor is faulty or the internal by-pass is at fault,either way you will need a gas safe engineer to take a look.
hope this helps.
Regards,Rob.

R.A.MOORE PLUMBING AND HEATING., December 2010

apologies - I meant Ao3 fault code.

Paddy M, December 2010