Potterton netaheat 60e earth fault

[JonSG]

Hi

I have been called out to a potterton netaheat 60e that is causing the main RCD to trip when the heating is called for. On my first visit I checked the obvious faults such as pump and gas valve and found no earth faults. I have since replaced the pcb which did not fix the fault. The symptoms are:
when hot water is switched to on the fan starts but there is no pilot light so the gas valve doesn't release. As soon as it calls for central heating it immediately trips the rcd. Further checks shows that the hot water stat casing becomes live on the NC pin once a voltage is applied to the C pin, however there is no resistance between the two when there is no voltage applied. I have stripped the stat down and can't see how the casing could actually become live..

Does anyone have any suggestions.

Thanks

Jon

 

[Agile]

You seem to be describing a boiler fault as well as an electrical fault on the cyl stat.

The boiler fault needs you to register for the CC part of the site where we can answer those questions.

Without seeing the cyl stat no one can tell you. Maybe posting a photo might help at least we could see which one it is.

You seem to have uploaded some pictures but then blocked anyone from viewing them!

But it does not follow that the case can become live when you say there is no continuity!

Tony

 

[geoff@cetltd]

what are you measuring with respect to, neutral or the case?

 

[Agile]

Hi Geoff!

Jon seems to have disappeared!