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Nest Thermostat E Installation issue

Discussion in 'Plumbing and Central Heating' started by Soong, 24 Mar 2021.

  1. Soong

    Soong

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    I thought this would be super simple as the E is battery powered so just isolate power and connect the two wires.

    No instructions I can find have mentioned anything about switches but my existing thermostat has TWO and the Nest install guide can't cope with two.

    Here is what I see:

    PXL_20210324_183419068.jpg

    Could someone please explain what I need to terminate and why it's such a mess in there?!
     
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  3. Soong

    Soong

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    Oh hang on I think I misunderstood the instructions.

    So now I think terminate everything in earth/l/n and the black wire in B is NO and the grey wire is COM?

    And I'm done?! Easy!
     
  4. CBW

    CBW

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    Decommission the live, neutral and earth, put wires a and b into switching (common and n/o usually).
     
  5. ianmcd

    ianmcd

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    A&B go to NestE NO&COM everything else needs to be safely isolated or totally disconnected, they are the 240v supply to your existing stat and as you say the nest E is battery powered
     
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  6. CBW

    CBW

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    Yep, grey com and black no.
     
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  7. Soong

    Soong

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    Cheers guys.
     
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  8. Soong

    Soong

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    Right, I thought I did it all properly and the Nest E is connected to the Heat Link fine but nothing will turn the boiler no - Changing the temp doesn't and putting the hot water on doesn't. The boiler has no power at all.

    I terminated all L/N/E wires but I assume that's what's caused it? Do I need to put each L/N/E in it's own block to create the power circuit for the boiler?
     
  9. DP

    DP

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    I thought you were suitably advised on your previous post on this setup:whistle::whistle::whistle::whistle:
     
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  11. Soong

    Soong

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    Ha, so did I. I did what I thought I was told and I then thought it worked as the heat link and therm both linked and said it was working.

    It was only when my wife tried to shower this morning did I realise how much trouble I was in!

    What I posted just above sorted it - All done now! Heat and water both working. I had just assumed it was working yesterday as the therm was saying it was heating and even giving a time until it hit heat. I was too tight to actually leave the heating on to find out.
     
  12. DP

    DP

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    Clearly you had a Ferrari with high performance engine and you have stuck a Lada engine in it without first studying the workshop manual :whistle::whistle::whistle:
     
  13. ianmcd

    ianmcd

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    what difference would putting them in terminal block make ?
     
  14. CBW

    CBW

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    I’m guessing the boiler l-n-e was fed via the existing thermostat?
     
  15. ianmcd

    ianmcd

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    but only single wires into each terminal, if that was the case it would need two wires in each terminal, as there are two earth wires the L&N may well have been joined somewhere else in which case isolating the single L&N in the thermostat wouldnt make any difference
     
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  16. CBW

    CBW

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    Looks like there’s a red wire and blue wire, so must not be connected? I see the brown and Black are connected.
     
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