Heating related electrical RCD trip

[Gforce37]

I recently renovated a property which included a totally new electrical and heating installation. The heating downstairs is a maincor underfloor heating system and upstairs it is a traditional radiator system. The system is pressurised and there is a new grant external boiler.

Since moving in we have been experiencing repeated but random (occuring on average once every 24 hours) trips on the RCD. We have traced this to a heating related problem as we have two switch boxes and whichever box the heating controls are wired too trips. We have checked everything to try to find the earth leakage including testing all of the pumps and the cabling. As most of the trips occur in the early hours (although not exclusively) we suspect the underfloor heating as it is the only heating related system that could come on at this time. We are starting to run out of ideas. Has anyone ever come across this before or could offer any tips please.

 

[Rappid]

Are there any timers connected?
Could be a fault on a thermostat

 

[Knobhead]

Can I ask who “we” are that's running out of ideas.
If this is a new build get the electrical contractor back and “kick ---”. If you’ve installed it yourself and subsequently can’t sort the problem, I wouldn’t deem you as competent.
Sorry but this site is getting choked up with enthusiastic DIY’ers asking for free advise to clear up a mess of their own making.
Sorry if I’m blunt, but it’s a reoccurring theme now a days.

 

[SirKit Breaker]

Are there any double pole switches? It may not be switching both poles at the same time quick enough, and so throwing the RCD coil out of balance.

Cheers............Howard

 

[Deleted member 9648]

These random tripping problems can be a nightmare to trace...I once had a similar scenario caused by occasional breaking down of a capacitor in a boiler PC....took weeks of trial and error to trace.
Could you isolate the separate parts of the heating system over several nights....ie upstairs heating...floor heating...hot water....pumps on but boiler isolated....etc etc? Once the tripping ceases you will have a lead on the problem.
All this assumes proper IR testing of all circuits and ramp tests of RCD's has already been carried out by a competant electrician.