How do the heat link and the thermostat talk to each other?

[CathLopez]

Is it directly without using the home Wi-Fi or do they talk to each other through the home Wi-Fi?

thank you in advance. 

[MickinMerton]

My understanding is that they communicate via radio signals but they are independent of WiFi, if your WiFi goes down the thermostat should carry on.

[markuk]

Two options: a wired connection, where you are replacing an existing wired thermostat. Or wireless option, where you are replacing an existing wireless thermostat - in this scenario you need the Nest stand to power the thermostat.