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Nest 3rdGen & Vaillant ecotec exl 385

Discussion in 'Plumbing and Central Heating' started by kzl, 18 Oct 2021.

  1. kzl

    kzl

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    Hi,
    I have just connected Nest Thermostat 3rd Gen to my Vaillant using this diagram:
    Boiler wiring.png

    Am I able to connect Thermostat to the wall wiring by replacing my old thermostat:
    Screenshot 2021-10-18 at 20.08.15.png

    Or does it have to be connected to the usb power?
    TIA
     
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  3. CBW

    CBW

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    If the Vaillant is wireless (looks it to me) then usb, if it’s wired, then you should be able to swap.
     
  4. kzl

    kzl

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    Thank you. Vaillant is wired, at the back of nest says not to connect it to 230V power therefore wasn't sure if I can replace it. Anyway seems it's not responding at all anyway so need to check the wiring again or i'm doing something else wrong
     
  5. ianmcd

    ianmcd

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    show a pic of the facia of the boiler
     
  6. kzl

    kzl

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  7. CBW

    CBW

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    You’ve got the eBus still connected and a 230v room stat connection. So unfortunately you can’t wire it, unless you take a separate wire from heat link to the Nest, so would have to be the usb otherwise.
     
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  8. kzl

    kzl

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    Thank you. So seems like the heating isn’t working. I can hear boiler making clicking noise (starting up) when I turn the heating up with nest or turn it down but radiators aren’t getting hot at all. What could be the reason for that?
     
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  10. CBW

    CBW

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    Have you removed the eBus wiring? (Black and grey on left hand side)
     
  11. kzl

    kzl

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    I have not. I didn’t realise I have to. Only removed the rt. I’ll try tomorrow. Should that fix the problem? Tia
     
  12. CBW

    CBW

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    Yes, otherwise it’s still looking for this.
     
  13. ianmcd

    ianmcd

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    As @CBW says, you will have to disconnect the Ebus or the boiler will constantly look for the old controller
     
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  14. kzl

    kzl

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    Just only managed to fix it today. Done as you guys adviced and it all finally seems to be working. Thank you for your time and help!
     
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  15. ianmcd

    ianmcd

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    A little bit of polite advice , if you need help post pics of what you actually have not a web found pic of someone elses, if you had posted a pic of yours before asked to , it would have been sorted immediately :rolleyes:
     
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