My Thermostat with the W5 error has been replaced last week. I receive a complete new box with Thermostat and Heatsink. so I called the Dutch Google helpdesk because I wasn't sure if I had to replace both. Replacing the heatlink is a lot of more work.
They asked me about the type of error and they told me it was not necessary to replace the heatlink in this case. So I clicked the new thermostat on the socket and my wifi environment was back again. Everything worked except the wireless connection with the (old) heatlink.
I was sure that the right 6 character heatlink code was entered into the thermostat. I didn't get it to work and I decided to replace the heatlink also. After it had been replaced, I entered the code of the new heatlink and after that everthing worked fine.
So my advice is, to replace the whole set!
Don't forget to send back the old stuff according the instructions you will receive from Google.
I am still curious why this wifi part stops working after a few months. Does anyone know?
