I have a baxi solo 3 50 which seems to not want to stay on! The rads just get warm and the HW is only luke warm. I have noticed that the pump also runs 24/7. The boiler fires up initially then goes off, the fan keeps running and you can see it keep sparking through the little window. After a while the boiler ignites again, this cycle happens continously. Is it most likely pcb problem or gas valve related (or something else??) Any thoughts gratefully received.