Notes for how to install a Nest thermostat kit in to a Vaillant TurboMax boiler

Discussion in 'Electricians' Talk' started by PaulTomps, Sep 30, 2020.

  1. PaulTomps

    PaulTomps New Member

    Hope I'm not breaking any forum rules posting notes, rather than a question, but I wanted to share this basic info in case it's useful to any one else doing the same thing:)

    How I wired my Nest thermostat kit in to a Vaillant TurboMax boiler (UK)​

    NOTE: if you're not very technical, or are unsure then get an expert installer to do this for you. These notes are only for reference, and not professional advice.

    First buy the Nest thermostat kit, and some cable to connect it to the boiler with. Best to get the 5m option in case you more length for the Nest transmitter/receiver box.

    Wire up the Nest transmitter/receiver box before you open the boiler up (image below), using the new cable you brought. Note to remove the bottom bit of plastic tab (under the cable), so the lid can close later.

    Now you can turn off boiler using it's front switch, at the wall power plug, and also remove the power plug from the wall. This is important as it'll be linked to the same power supply, and it should not be live while you're working on it!
    This my model of Vaillant TurboMax boiler I installed it in.

    Open the boiler, then remove the circuit access panel.

    In the boiler note that the power cable is threaded through a secure hole. Loosen it with a screwdriver, so it can be pulled through to work on...
    20200929_123229 (1).jpg
    Now loosen all 3 of the cables that come from the power cable in to the circuit board, and also remove the red 'looped' cable in 3 and 4 holes.

    Now thread the new/additional hive cable up through the bottom of the boiler, following the power cable route, and install 2 cables per hole where needed (2 live, 2 neutral, 2 earth) from the original power cable+the new one, then the black and grey cables from the new cable, as per the image.

    Once you're happy its all secure, tighten up the plastic screws that hold the power/hive main cables in place, pop the plastic access panel back on, then close back up the boiler cover.
    Now wall mount/pop the front cover on to the Nest transmitter/receiver box.

    You should now be ready to turn the boiler to the middle 'manual/always on' option, then put the power cable back in, and turn the boiler on.

    After this you're ready to do any required next steps on the Hive setup phone app etc.!

    NOTE: if you're not very technical, or are unsure then get an expert installer to do this for you. These notes are only for reference, and not professional advice.

    Attached Files:

  2. MGW

    MGW Screwfix Select

    Nest heat link looks like this upper_wiring_centre_plus_heatlink.jpg are you sure your instructions are not for Hive?
  3. PaulTomps

    PaulTomps New Member

    Doh, you're correct I've used the wrong brand name! I'll contact mods to see if I can edit the post. Thanks :)
  4. Tuxmark2

    Tuxmark2 Active Member

    The picture explains why its called a nest :D
    MGW likes this.
  5. Tuxmark2

    Tuxmark2 Active Member

    Top job for getting those images and putting a guide together, I had the exact same boiler until a few weeks ago, not the easiest board to get at and take pictures of the pcb, its a pity the forum doesnt offer to stick posts like this so its easy to find.
  6. MGW

    MGW Screwfix Select

    Yes there is one boiler and two heat areas flat and house with there own pump and motorised valves, on a C Plan of all things so it did get a bit complex picture was before finished, in fact still not finished I need another relay fitting but Flat not used so no hurry. Main reason for Nest is only two wires between main house and Flat and Nest takes power and data on two wires so I can control DHW and CH from house to flat with just two wires, it was not fitted for geofencing or internet control however now fitted it is used. So some thing like this C_Plan_My_House-DHW.jpg Which if you study you may find the error, as said needs second relay. The other thing was ability to control C Plan where there is no tank thermostat or motorised valve, advised it was not good the run the boiler I have when it can't cool by heating DHW when turned off. When I bought the house last year, to turn on house central heating you turned on a time switch in main house, went outside and down some steps into the flat under the house, and manually plugged in the house pump. No less than three FCU's powering central heating, and no thermostat at all in the house, looked as if there had been, but thermostat receiver but no sender. Where likely thermostat was a cable sticking out of the wall. No motorised valves just two pumps, and if you ran flat central heating pump only, main house radiators heated up but not as hot with water reverse flow, and which house only pump flat still heated up with reverse flow.

    I had expected the plumber to reduce to one pump when fitting the motorised valves, but he didn't he retained the two, which resulted in needing relays, and I had a blond moment and only fitted one. My worry is 69 now how long will I be able to wire things up for? So want to make a good plan so if I can't repair my self, some one else can follow what is installed. Leak in flat roof so no hurry to finish. But some day need to fit second relay.
  7. Tuxmark2

    Tuxmark2 Active Member

    You don't have to worry about wiring things up at 69, I still manage just fine, hands shake a bit and only blew myself up twice this year, dropping a spanner on a leisure battery and lightening striking my garden wheelbarrow, while I was five foot away :-( I wouldn't mind but I was gifted it and fitted a new wheel and now its got a hole in the hopper.

    Those heating wiring centrers always end up rammed full of wiring, they need to make a larger version with two rows of terminals.
  8. Davidjkelly

    Davidjkelly New Member

    Brilliant thank you been looking all day for a simple “idiots” guide.
    That’s Saturday job then
    PaulTomps likes this.
  9. PaulTomps

    PaulTomps New Member

    Note that I messed up and called it a 'Nest' guide, when it's actually for Hive! Unfortunately I was researching both around the time of purchase and mixed the names up.
    I did reach out to mods to change it, but no joy.
  10. Davidjkelly

    Davidjkelly New Member

    Yeah noticed that. found a bit online about the Nest wiring but I've decided to go with the Hive mainly due to it not needing plugged in.
    How are you finding it
  11. PaulTomps

    PaulTomps New Member

    I'm really liking it so far. Its usability isn't perfect, and the software could be improved, but I think it's still a great product.

    I'm still getting used to the system, and tweaking it, but having the option of pressing a button in the app to control it is awesome.
    I've also got the 'Hive smart TRV' valves on all the radiators too.
  12. Arthur Dent

    Arthur Dent Member

    How are you getting on with the Hive TRV's I keep looking at replacing our current ones with those, though I do baulk at the price, we will have 7 or 8 to replace.
  13. PaulTomps

    PaulTomps New Member

    They work really well, but I'm still figuring out what temperatures work best in each room, so I'm fiddling with them/the app a bit too much at the moment.
    I will say that their setup process is a bit flakey, but not too painful. I'm definitely happy I got them, and the main benefit is the luxury of controlling/boosting the temperature of each room via my phone whenever I choose.

    I can recommend them, despite them being a bit pricey.

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