1. White continuous: Start-up after the Boiler interface is energized. (from start up to 5 seconds). If after step 1 the LED goes out and remains off, the thermostat is not connected or defective.
2. Red flashing: Firmware is corrupt and is reloading.
3. White flashing: Firmware (for the boiler interface) update is in progress.
There are also colors that the application uses:
4. Green continuous: OT works well (data goes to and from the boiler.
5. Green flashing: No OpenTherm message from the boiler. Check the connections (also in the boiler) and the cable.
6. Yellow continuous: On / off boiler relay active, the boiler should burn.
7. Blue continuous: DHW (DHW) relay active, the tap water should be kept at temperature.
8. Blue / Yellow flashing: Both relays (boiler on / off and DHW) are active