Main Combi 30 HE tripping the fuse board

[Kewat66]

Hi All,
i am looking at a Main 30 HE combi that is struggling to get going. It does after a few attempts fire up but as soon as it gets going and lights the burner the main rcd on the consumer unit trips. I am looking at changing the board. Has anyone had anything like this before and if so what was the solution?
Thanks
kewat66

 

[buckley plumb]

Check boiler for earth faults. Live to earth.

 

[Billy Bob Bob]

check pump and gas valve lead first,pcb not common for doing this on this boiler,also check flow switch bushes not leaking

 

[stevetheplumber]

fact that its strugling to start i would be looking at the fan or pump first

 

[Chris F]

My moms was doing this,the Fan was mullered.

 

[bewsh]

My mates was doing this, it was the gas valve lead.
Unplug it and see if it trips