Extension kit setting zero target flow temp over eBus

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I have a Vaillant ecoTec Plus 637 boiler controlled over eBus by an Extension kit and a wireless thermostat, along with Tado TRVs.
The system has been working for years. However, this week the heating stopped working. Looking at the boiler diagnostics the target flow temperature was set to zero. Replacing the extension kit with the old Vaillant thermostat restored the correct target flow temp and the boiler worked OK. Put the extension kit back in pace and the problem reappears (so it seems it’s the extension kit at fault). Everything else works OK - the TRVs are controlled correctly etc.

It sounds like a firmware problem to me, but Tado support hasn’t responded to my queries.

Does anyone have any ideas?

Thanks.

Answers

  • johnnyp78
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    Have you downloaded the Tado pro app? If not, see what the flow temp is set to in that.
  • Montage
    Montage ✭✭✭
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    Sounds faulty. I’d probably be buying a replacement.

  • AJEngineer
    edited January 2023
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    The Pro App doesn't seem to give target flow temps for eBus installations – only OpenTherm (unless I'm missing something). The actual "current flow temperature' is read correctly (as is the configuration of the rest of the installation).


    As for the unit being faulty, it sends other eBus commands OK, and communicates with the TRVs, Internet Bridge and so on, hence my comment that it's likely to be a firmware issue.