How to install Nest Thermostat 3rd Generation – UK

How to install the Nest Thermostat 3rd Generation yourself in the UK. A complete step by step DIY guide on how to install the Nest 3rd Generation Learning Thermostat to a Worcester Bosch Greenstar 30si Compact. Including how to fit the Nest to an official Nest stand.

I take you from the beginning, opening the box, going through the contents, installing the wiring to the Heatlink, wiring the Heatlink to the boiler, how to set up the Nest and finally turning on and using the Nest.

Nest Learning Thermostat 3rd Generation:

Nest Stand for 3rd Generation Thermostat:

These links are affiliate links, which means if you click the links and make a purchase, I’ll receive a small commission. This helps to support the channel and allows me to continue making the helpful videos I do.

Please only attempt this if you are competent enough to do so. I have tried to simplify it but you do need a basic understanding of home electrics.

#nest #nestuk #nestthermostat

44 Replies to “How to install Nest Thermostat 3rd Generation – UK”

  1. Mr Bastami

    Hi Mate, awesome how to video, one question from me, when I open existing thermostat (is a Honeywell ) wires look like this picture, 4 cables goes to N and 3 cables goes to L . I wonder how to translate these to nest ? As from what I can tell nest sockets are so tiny and won't accept 4 cables in !!! Any help appreciated.
    Cheers and happy New year 2019 in advance

  2. Charles Biscoe

    Best installation video, but I'm still struggling with mine. I have a Vokera Linea HE which is Open Therm compatible and would like to use that capability. There is an existing wireless Vokera thermostat and receiver but I can't work out the connection from the HeatLink to the boiler. Any suggestions (…/linea-he-combi-boilers-installation.pdf) Thermostat manual (

  3. Lennox M

    My current wireless thermostat receiver only has two cables connected to the boiler: live & neutral. Will the nest thermostat work with only those two cables?

  4. MrCgoodwin

    Hi Charlie just bought a nest,watched your video which was great.I have a thermostat in the living room but will be mounting my nest on the stand.can you tell me what I do with the existing thermostat and wires?do I just remove?Also like you said in a previous post in the Americans videos they only show you replacing the thermostat for the nest and not the heat link.Do you have to have the heat link if you have an existing thermostat?

  5. Robin Davies

    When you are connecting the wires at the heat link end, you don't actually mention into which slot the black (call for heating) wire goes. Could you please clarify? Thank you

  6. Adam Wolley

    Watched this before ordering as I thought £120 for installation seemed a little much, your vid made it super easy and I was done with a working Nest in less than 40 mins. For reference I was fitting to a Worcester Bosch 28CDi and the wiring setup was as shown on your slightly more compact model. As with EJ wheeler below I had to unplug the front panel for a previous wireless thermostat to make it all work. Thanks!

  7. Tony ORourke

    I’ve got an old manual wired thermostat in my lounge. So I take it I don’t need to wire the nest to the boiler. A Worcester condenser boiler. Is it a matter of replacing and wiring the nest on the wall wired into the current thermostat wiring.

  8. Darryl of Sussex

    I have a Bosch control unit which is powered from the boiler via a control cable. It doesn’t require a 240v power adapter or plugging in and does the same job, which is useful, as the nearest power point is on the other side of the room and it can be remotely used via an app.

  9. Sheepish

    Hi Charlie, thanks a lot for this video. It's given me the knowledge to wire in the Heat Link but I wonder if I could trouble you for some advice on replacing my existing thermostat? It's a bit of a puzzle.

    First, the boiler is an Ideal Logic 35 and the thermostat a Honeywell CM707. On the boiler I have T1 (black), T2 (grey), L (brown), N (blue) and Earth (green) all coming in on a 6 core cable (one wire looks like another grey, has been snipped and is not terminated?). I expected to open the battery operated Honeywell and find black and grey that I could reroute from the boiler to the Heatlink T1/T2 which outputs 12V but instead I have A (brown) and B (black) – Live and T1? What's could T2 (grey) be connected to?

    Honeywell manual shows 2 different valid configs :
    1) A to external Live and B to Boiler Live (with Boiler N to an external Neutral) – I'll be honest and say I don't know what this really means
    2) A to T1 and B to T2
    All I can think is that somewhere between the two there is a junction box where colours are being switched? Either Honeywell B (black) is being switched to Boiler L (brown) or Honeywell A (brown) is switching to Boiler T2 (grey)?
    I'm going to get a multimeter tomorrow and test the voltage across A and B on the honeywell. Hopefully this tells me it's not 230V which means it's not connected to Boiler L?
    I could also disconnect the grey to see if it has any effect on the Honeywell firing the boiler?
    Any other suggestions?

    Appreciate your time and I'd be happy to make a donation to you or charity if you can help. Thanks!

  10. david young

    Hi Charlie thinking of buying a nest. At the moment I have a Honeywell wireless programmer and a ideal boiler . So my boiler connection should be ok just replace Honeywell receiver with the Nest receiver, but this is where I hit a little problem on your insulation you fit the neg and put a link from the live and then put your switched live. on my Honeywell I just have the supply from the boiler supply then from the external stat connection in the boiler blue and brown to the other two connection in the Honeywell. Any ideas on which wire to use as the switch wire . Iv just finished the night shift so this might not make sense in the cold light of day

  11. captainchuppachup

    Some YouTube videos just seem to plug the nest directly onto their existing thermostat? They also don't see to have the heat link when they're unboxed. Is the heat link a UK specific thing? Is there a difference between wiring via heat link or directly? So confused 🙈

  12. Robert Green

    Excellent video but at 2:25 you say 'that's how we will be wiring ours in' but you don't. The Nest diagram seems to be turning the boiler on and off via the mains using the Heat Link when calling for heat. Surely that can't be right? I have a Grant Vortex Pro Combi 26e with an external programmer and wall thermostat. The HW is switched via the programmer and the CH is controlled via the thermostat and the programmer. Thanks.

  13. Alpa Chino

    Just remember folks, you have to be, or have the installer be, Gas Safe registered to take the front panel off the boiler. There was no reason to take the front panel off in this instance, but on some boilers, you need to completely remove the front cover to get access to the electrical connections.

  14. Melvin Evans

    Hey mate great video and gives confidence in myself to actually attempt but have only gotten as far as pairing the heatlink with boiler but didn’t want to fire up
    And was hopeful in some input please fella

    Have connected L N to power on boiler and back to heat link L N also connected black cable from 5 core flex to RT on my x1 plug and back into number 3 on heat link but won’t fire up is there something you could suggest all bar asking a technician to arrive I’m gas safe safe but don’t really do electrical works this is for my home boiler any help would really appreciate it
    Vaillant ecotec plus 825 Combi cheers

  15. Alex Masters

    Hi Charlie great video thanks, just had a question about your earth wire. How come you did not wire that into the Earth point in the heat link? Would love to know, cheers!

  16. Suraj Rana

    Great video but bit confused, if I’m not wrong blue to N, brown to L and loop to 2 and last one black to 3 on nest control? Coz your wire connection not very clear.

  17. Frankie F

    Thanks for sharing this, nice and clear. Neat job with the conduit, really like that you don't see the wires going into the heat link. I know the box is plastic but since there is an earth terminal next to the 12v why not connect it?

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