ferroli tempra 30 strange behaviour

[gandkslater]

replaced venturi but boiler still only firing with case off. replaced fan assembly and all was well - for a day. Then the boiler fires up, runs for 10 mins then goes off but pump does not continue (no pump overrun) and the green demand light is not on - ie it doesn't flash green. After cooling the boiler fires and runs for a couple of minutes before repeating the cycle.
Both thermostats (limit and overheat) are closed when the boiler stops firing, and the thermistor is within range. I have changed the PCB. Just can't understand why the pump doesn't keep running after the boiler shuts down. This is a PCB controlled function surely? Help!

 

[Riley]

Need to take a look at the forum rules buddy. If you are Gas Safe get your posts up to 10 and message a mod. If not what you're doing is illegal and very dangerous