Nest 3rd gen heat link tripping the electric.

[ricflairandy]

Hi,

My nest 3rd gen is tripping the electric evertime it clicks. Manually or via the thermostat.

It’s been fine for about 7 years but this do happen once a few years ago and an electrician took a look , but it started working and had been fine ever since.

Any ideas? Wiring picture attached, I’m waiting on an electrician at the moment.

 

[CountryFan]

Sounds like an internal component has failed and is allowing 2 of the conductors to touch. Will likely need a new heat link.

 

[RandomGrinch]

My nest 3rd gen is tripping the electric evertime it clicks. Manually or via the thermostat.

What exactly is tripping - is it an RCD, or MCB? Can you show us a picture?

Is this the same Danesmore 20/25 boiler that you had problems with locking out in 2017?

The wiring arrangement looks unusual on the Nest (edit: although I may be missing an extra loop into terminal 2), but if it has been working and it's an RCD that has tripped, I would suspect something water related like a pump, or powered valve as the cause of a trip.

 

[ricflairandy]

What exactly is tripping - is it an RCD, or MCB? Can you show us a picture?

Is this the same Danesmore 20/25 boiler that you had problems with locking out in 2017?

The wiring arrangement looks unusual on the Nest (edit: although I may be missing an extra loop into terminal 2), but if it has been working and it's an RCD that has tripped, I would suspect something water related like a pump, or powered valve as the cause of a trip.

Yeah same boiler. It’s tripping before anything even happens with the boiler, it’s instant when you push the heat link button or the instant (which is a few seconds after using the app) that the thermostat sends the signal.

It basically trips the entire electric in the house and I have to go and flip it back.

 

[RandomGrinch]

. It’s tripping before anything even happens with the boiler, it’s instant when you push the heat link button or the instant (which is a few seconds after using the app) that the thermostat sends the signal.

Yes, that's the RCD that has tripped.
Due to the nature of how the Nest is made, it is extremely unlikely to be the problem.
Your system seemed to be an S-Plan from your last posts?
Again, I suspect a problem further down the line, i.e. a powered valve or the pump - something of mains voltage, with an earth connection, and probably some water leak/corrosion - these factors would allow earth leakage that would trip an RCD.