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Signal between Nest & boiler not working

Community Member

Hi-- I am having an issue with my Nest connecting to my boiler. I have checked my boiler by turning on the emergency heat so know it works. My Nest was running this morning, but then stopped. The Nest faceplate reads  "Heating..." so it clearly is calling for heat, but the boiler doesn't turn on. Something seems to be interrupting the signal from the Nest to the boiler because the boiler can operate, and the Nest recognizes the need for heat.

I would be grateful for any ideas on what the issue might be. 

Thank you!


Silver Product Expert
Silver Product Expert

Is this a hot water heating system with baseboard heat or radiators?

Just checking because you said emergency heat but most boilers do not have emergency heat.

Or do yo have a heat pump A/C system and also a boiler for back up heat?

Do you have a picture of the original thermostat wiring before the Nest was installed?

If yes upload it.

And take a picture of the Nest wiring now and upload that also.

Houptee -- NJ Master HVAC Licensed Contractor

Community Specialist
Community Specialist

Hi folks,


I'm just dropping by and see how I could help.


Thanks for your assistance, @Houptee.


@leilam, I wanted to check if you have seen the response posted above for the additional details. This is to check and see why it's not activating your heat.


Additional questions: Did heating ever work with the Nest thermostat? Also, is the Nest thermostat newly installed?


Looking forward for your response.


Best regards,


Hi leilam,


I Just wanted to see if you still needed help. Please let us know if you have any other questions or concerns.


Best regards,


Hi leilam


Chiming in to check if you have additional questions or concerns as we will be locking this thread in 24 hours.