If you provide power to the boiler interface, the status LED will light up. The color and any blinking patterns are an indication of how it works. The LED should light up immediately when you plug the adapter into the wall socket.

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