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Google Nest 3rd Gen Learning Heat Link Failed

Community Member

The thermostat is showing a H72 error message. The heat link has lost all power, will not reset or turn on. There is power to the switch as it also powers the boiler, which works fine (manually). The thermostat loses power on its base after a short period charging via a cable. After looking at various threads I believe the heat link has failed and needs to be replaced. My product is 1 1/2 years old.


Community Specialist
Community Specialist

Thanks for reaching out. I'll do my best to get this sorted for you as soon as possible.

Here are some helpful troubleshooting steps:

Press the button on the Heat Link and check if you have any lights on it
Check if the circuit breakers and the switches are set to on
Turn them off and then back on 
Press on the button again and check for LEDs

Could you also help me with some answers to these questions?

How long has your thermostat been installed for?
Did the issue happen during the installation?
Is there any error on the Nest thermostat display?
Have you had any power cuts recently?
Have you had any work done on your electrical or heating systems recently?
If yes, was the power properly restored at the fuse board after work was done?
How many zones ( thermostats ) are present in the setup?


Thank you for your reply.

I have been in contact with Made by Google who will be sending an engineer and replacement unit FOC.

Community Specialist
Community Specialist

That's great. I'm going to lock this thread. Should anything come up, feel free to open a new one.