Hi i have a ferroli optimax 31c , hot water works but my heating dont ,it comes on the the heat temp raises to its highiest then cuts of saying A3 AND D2 can you help please

Try bleeding the air out of the rads then represure system

Is there an error code? If not the flow sensor for the hot water could be faulty. Also if you've had a power cut depending which model of Optimax HE you have, you sometimes have to tell the boiler it's a Combi, as they have a generic Pcb fitted which is also used on the system only boilers.

Heat exchanger blocked or pump failed, the boiler is overheating internally.

Did you ever find out what this was as I have the same problem??

There is a parameter on the pcb to change would take 30seconds to do. Never replace ur pcb for these faults. Hold down reset untill u see t5 press reset 1 more time it will then say p01 press the heating temp button until u see p02 press the hot water temp button until it changes to numberv2 and that will fix ur problem

it is either your pump is not running or blocked [ debris from installation ect ] or your diverter valve is stuck partially open allowing a little water to pass into the heating system [ usually first rads on system ] it runs for a short while and cuts out because your overheat stat is kicking in because of poor circulation [ it is only running around the primarys in the boiler where it quickly reaches the over heat limit ] temp tends to rise approx 1 deg per second a clear indication of circulation problems.
solution GET RID OF THE FERROLI

Here you go, page 30, sounds like it's overheating, possibly a problem with the boiler stat or lack of circulation in the system. http://www.ferroli.co.uk/Product_Documentation/Domestic/Optimax_HE_31_C_Manual.pdf

D2 is not a fault what that means is delay and 2 refers to CH which means the boiler has gone into standby mode. you need to check that your CH circut is open, there is a filter on the return valve into boiler make sure this is not blocked. If this is blocked the water is just going though the boiler by-pass so then the boiler thinks its up to temp. hope this helps

d2 is the code symbol for delay after central heating. and is not a fault code.. however if this is coming on then stopping the operation of the boiler then it usually points to a sticking diverter valve.

Here is a link to the manual.It shows fault codes.
http://www.ferroli.co.uk/Product_Documentation/Domestic/Optimax_HE_31_C_Manual.pdf

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