Showing results for 
Search instead for 
Did you mean: 

Nest learning thermostat stopped turning the boiler on

Community Member


I have a nest learning thermostat which has been working ok* for a year and a half, and suddenly stopped turning the boiler on. The boiler is fine, I tried alternative wirings. Nothing works. The nest "looks" fine: turns orange when setting the temperature higher than the current temp etc.

Any ideas? I'm pretty sure it's an issue with the Nest itself.

(*) Temperature control was fine, WiFi connected according to the nest, but "offline" from the app most of the time.

More details:

  • Boiler-only system
  • 2 wires R and W coming from the boiler (connected to Rh and W)
  • External 24V transformer connected to C and Rc
  • The boiler is works fine: twisting the R and W together turns it on fine
  • Tried switching R with W and the two wires from the external transformer
  • The transformer on the boiler and the external transformer are out of phase (but nothing I can do about it)
  • Thought about trying the Nest Power Connector, but my setup worked before, so I don't see why I would need it now.

Community Specialist
Community Specialist

Hi gregleleu,

Thanks for reaching out and sorry for the delay. I'd love to know more about this. Could you share a photo of your current thermostat's wiring? 


Hey gregleleu,

Checking back in should you still have some questions here. Let us know by replying to this thread. 


Community Specialist
Community Specialist

Hey there,


We haven't heard from you in a while so we'll be locking this thread if there is no update within 24 hours. If you need assistance or want to discuss topics, feel free to start a new thread.