Ferroli compact 30

Hi Guys, I heeded and took your advice regarding calling in a Gas Safe engineer to look at this F5 fault on this Ferroli compact 30 boiler. It was good advice and I thank you for it. As I explained I am an electrical/ electronic engineer. When the gas engineer called he immediately took a look at the fan which was although free was not turning. I was able to assist the gas engineer with my expertise as he confessed that his knowledge of electrics was limited . We had some very strange readings with his meter and both sides of the motor was live with respect to earth . I knew the mains supply was the correct polarity and so suspected we had lost the neutral supply somewhere. After going around in circles for a while I found what the issue was. When they put the cables into the non reversible plug which feeds the pcb they had reversed the wires ie neutral was live and visa versus see picture. So the reason the supply to the fan was live with respect to earth was that the neutral was in fact the live.
We still have a fault where the fan is not working , I have the pcb on the bench right now, the relay that switches the fan on is mechanically and electrically sound but too tired tonight. The gas engineer will return tomorrow and do his checks, I suspect I will have to replace the pcb and get it all checked out. Thanks for advice fellas, anyone familiar with this pan.

Rog

Just an update on my quest to find this F5 fault. My gas engineer removed the fan and it’s tested ok on my bench. I have reversed the neutral and live input to the board and now everthing is making sense when taking voltage measurements, we now have zero voltage on fan where as we had 230 volts before. As the fan is ok, I tested the board on my bench and found that the relay which switches the fan is mechanically and electrically ok. The voltages on the board seem to be it the ball park but that’s about as far as I can go without a circuit. I’ve asked my gas engineer if that there are any sensors that would inhibit the relay being pulled in but he was unsure . I’ve taken a punt and orders a reconditioned board. Had it very cheap and it’s under 12 months warranty. As my fault finding experience tells me, if it doesn’t cure the problem at we have eliminated from mystery .
Thanks for listening
Rog

Update, diagnosis correct, reconditioned board came today , fitted, fired up straight away. Gas engineer checked it all out and reassembled . Thanks for your help and advice.
Rog