Nest 3rd gen wiring issue

5 Dec 2019
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United Kingdom
So I’ve bought a nest 3rd gen to add to my old valiant boiler.My brother is quite handy with electrical stuff and such so I asked his advice for wiring. He said this .

From what I can tell the Nest Heat Link (controller) has identical wiring, so you’d just need to replicate the wiring that you currently have for the Drayton controller, i.e. Blue to N, Brown to L, then a loop between L and 1, 2 is not used, the wire with sleeve to 3, and then Green/Yellow to the Earthing point.

I’ve wired it up fixed in place and done the app connection but it’s not calling for heat and won’t start the boiler have we got the wiring wrong ? Any advice please I have included a picture of the old Drayton wiring configuration.


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Looks like you have the loop from the live to the 1 terminal. It should go to the 2. post a pic of your Nest wiring. Can’t see exactly what you’ve done.

but your brother’s advice is wrong -
live should go to the common (2) terminal.

perhaps he isn’t as handy with electrical stuff as he makes out!
Thanks ! I told him ! He said move it to 2 after I sent a diagram and it wasn’t working ... but he was hard to get hold of . About to give it a go but sounds like it should work ... thanks a lot !

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