Various error messages can appear on the ThermoSmart display:

  • OT communication error: this message appears if the OpenTherm communication is working but no data has been received from the boiler for 1 minute.

    : this is a self-repairing error. When this message appears it is advisable to check the wiring between the ThermoSmart and the central heating boiler. The wiring must be properly connected and must not exceed a total length of 50 metres and the resistance must not exceed 5 ohms per conductor.

    If after checking the wiring the OT error is still displayed, try turning the boiler on and off. If on/off appears to work, the boiler interface may be broken. Create a support ticket and report the steps you have already taken. We can send you a replacement boiler interface as required.

  • Boiler^ followed by a number: this is a message from the central heating boiler that something is wrong.

    : consult the instructions of the central heating boiler to see what the number means. If required, ask an installation engineer for help.