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Reducing 230v to 12v for Nest

Discussion in 'Electrics UK' started by Gorners, 22 Dec 2016.

  1. Gorners

    Gorners

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    After installing Hive and finding the thermostat overrun is shocking and doesn't control the temperature properly, I've gone and bought the Nest. What made me choose Hive over Nest originally before was not having to hard wire the thermostat (don't want to plug it in and have wires showing).

    I thought I'd got this sussed using old thermostat wiring from the boiler before the one I have now which used to be in an airing cupboard (it's in the garage now) which is completely unused. Annoying I overlooked the fact that it needs 12v and not 230v. The spur where the thermostat wire runs from is right next to a completely unused fused socket which has its own MCB on the fuse board.

    Can I buy one of these:
    https://www.amazon.co.uk/gp/r.html?...ERPVGIX3UTA0A&ref_=pe_385721_37986871_TE_item

    and convert the fused socket to a normal socket for a plug, then connecting the other end of the transformer to the thermostat wire which then runs downstairs where I'll connect the new Nest?

    Assume this will deliver the required 12v and not fry the stat.
     
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  3. oceansoul

    oceansoul

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    Does the nest heatlink module not have a 12VDC PSU for the thermostat?

    From the nest website [​IMG]
     
  4. ban-all-sheds

    ban-all-sheds

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  5. Gorners

    Gorners

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    It does but I'd have to run a new wire from the garage to the hallway which I don't want to do as it would mean a lot of mess chasing out walls etc.
     
  6. endecotp

    endecotp

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    It will probably work. Does the nest say how much power it needs?
    You might worry a bit about the length of the wires between the power supply and the nest; odd things can happen when they are very long. How many m approximately?
     
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  7. Gorners

    Gorners

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    I reckon about 3m Max.

    Not got the book on me at the moment but I think the plug only supplies 3v so it will work with much less.
     
  8. endecotp

    endecotp

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    Probably OK.

    I hope you mean 3W, or maybe 3A....
     
  9. ban-all-sheds

    ban-all-sheds

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    If you have a power source which you could use for a plug-in 12v supply, why can't you use it for the Nest one?
     
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  11. Echo the husky

    Echo the husky

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    That one you linked to will be fine.
     
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  12. Gorners

    Gorners

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    Apologies, it's 12v from the heat link and 5v from the USB.

    That's for the replies, will report back when I've got this hooked up hopefully tomorrow.
     
  13. muffking

    muffking

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    I don't get why this wouldn't work. If you're considering changing the spur to a socket then the Nest USB power supply would be ideal for the thermostat.
     
  14. Echo the husky

    Echo the husky

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    Yes but then you would have an unsightly usb connector sticking out of the nest, with 12V you can connect it in behind, concealing the wiring.
     
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  15. Gorners

    Gorners

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    Yeah exactly that. If I can reuse the old thermostat wiring then I can position the Nest in the ideal location mounted on the wall. The spur is in an airing cupboard so any modifications in there is also out of sight.
     
    Last edited: 22 Dec 2016
  16. EFLImpudence

    EFLImpudence

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    A battery option would save all this fuss.
     
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  17. Gorners

    Gorners

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    Thanks for all the help guys, wired it all up today and all is working fine.
     
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