Boiler not firing – Error symbols on Thermostat – Worcester Greenstar 28CDI Compact

I've installed my Extension Kit and Smart Thermostat following the installation instructions from Tado (it was fairly simple, two wires to the boiler from the extension kit).

All appears to be set up correctly, but the boiler does not turn on when I set the desired temperature higher than the current room temperature. Additionally, the following symbols are shown on the Smart Thermostat.

Any ideas what's wrong?


  • Assuming picture one is a world, and picture two signal strength, it may mean tado isn't getting connected to your Wifi or it is connected to the Wifi, but you don't have internet connectivity. Those symbols don't appear in the manuals I've seen, so I'm wondering whether your device has been in the box a while and needs an upgrade. In the absence of tado specific advice I'd be tempted to reset the bridge, extension and thermostat in the hope they pick up any updates they haven't yet completed.

    I imagine you'll get a better answer from tado when working hours resume.

  • Hi, Thank you for your response Ditsy!

    Yes, the firmware versions of my extension kit and thermostat are very old, but I haven't been able to get them to upgrade yet. I was reaching the same conclusion as I am unable to find the symbols anywhere else.

  • The second picture (4 vertical lines and x) indicate that there is no radio link to the bridge.
    Try moving the bridge closer to establish a connection.
    Hope it helps 😊
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