If you need to replace your physical Sensi with another of the same device, you will need to reconnect the Wi-Fi connection once replaced.

When it arrives, you should be able to take the new Sensi and plug it into the existing base plate on the wall (assuming that the issue you were having was not related to the wiring and operation of the HVAC).

To connect this device to your Ecovent system, simply go to the "System Settings" found in the main menu of the Ecovent app, scroll to the bottom of the screen and select "Replace Thermostat" and follow the instructions for connecting an installed Sensi to Wi-Fi.