Nest thermostat install help. Underfloor heating

Discussion in 'Plumbing and Central Heating' started by Braddels, 12 Feb 2020.

  1. Braddels

    Braddels

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    Hi everyone.

    first, let me say I have no idea about central heating so bear with my ignorance and potentially stupid questions.

    I currently have 4 heating zones. 1 controls upstairs radiators and then 3 control the downstairs ufh. I wanted to swap my existing thermostats for the ufh to nest so they were more user friendly. I had a few people come round last year who looked at the system and said it could be done but at the time I wasn’t ready to go ahead with it. I finally booked someone in to come round today to install it and after about 40 minutes he said he doesn’t think it can be done. He said because my current thermostats were wireless he can’t figure out how to wire up the heatlink to make it work.

    I spoke to Nest technical support and explained about my system and they confirmed it would work fine and I did see another post from last year on here that sounded similar to my setup and they got it working fine.

    Attached are some pictures of the ufh manifold and John guest wiring centre. Can anyone confirm that this should be ok? I’m hoping it’s just installer inexperience rather than an incompatible system.

    If you need more information on anything let me know

    thanks
    Brad
     

    Attached Files:

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  3. stem

    stem

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    Unfortunately I've never seen a JG control centre used with wireless thermostats. However, if the wireless thermostats have receivers which are connected to the same terminals as a wired thermostat would be, as below...

    zones.JPG

    ...then a Nest Heat link can be connected to each zone in their place.

    SL = Nest (3) Heating call for heat
    N = Nest (N)
    L = Nest (L)

    A link would be also required between Nest (L) and (2) Heating Common

    On the other hand, if the wireless receivers are an integral part of the control centre and not connected to these terminals I have no idea. Sorry.

    Some JG thermostats also have optional communication for 'thermostat grouping' and remote sensors. Nest doesn't support these.
     
  4. muggles

    muggles

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    It should be possible, but if your existing thermostats are wireless, have you thought about how you're going to power the Nests? They need a permanent power supply, they don't run off batteries
     
  5. Braddels

    Braddels

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    the current thermostats are wireless but are hardwired for power so the best would just take it’s place and draw power from the live wire
     
  6. stem

    stem

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    Nest has two parts. The Heat link which requires 230V power. (This is the bit responsible for the electrical switching) and the remote wireless thermostat which requires 12v to power it. This can be obtained by wiring the thermostat back to the 12v terminals T1 & T2 at the Heat link, or by using a separate plug in power supply for each thermostat. The thermostats themselves cannot be connected directly to the mains supply.
     
  7. ericmark

    ericmark

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    Nest Gen 3 as @stem says, Nest e is battery operated, both the heat link and thermostat.
     
  8. ianmcd

    ianmcd

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    Not so, the Nest E heat link is battery powered, the Nest E thermostat has a USB cable and is plugged into the 230v supply using a transformer plug, there are no batteries in the Thermostat
     
  9. ericmark

    ericmark

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    Sorry it seems the battery in the thermostat will only last around 2 hours, so it needs a USB power supply, which of course could be a battery.
     
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  11. Braddels

    Braddels

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    So it turns out my system isn’t compatible with Nests. how big of a job would it be to replace the control centre with something new? I already have a number of Nest products in the house so would be convenient to find a solution that would allow me to keep everything Nest
     
  12. muggles

    muggles

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    In what way is it not compatible? I can't see any issue from your photos and description
     
  13. Braddels

    Braddels

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    I spoke to John Guest and they said it’s not compatible. The Nest Pro installer who came to do it couldn’t figure out how you would get the nests to take over controlling the heating
     
  14. ianmcd

    ianmcd

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    John Guest are wrong, it can be done, definately not straight forward but definately can be done, I know you want to stick with nest, but if it was me I would use Hive single channel units for each zone , just because the Hive thermostats are battery powered so no power supplies to worry about, however if you are happy to use the nest thermostats on a stand then you can position the stats next to a power supply and use the USB cable,if your existing thermostats are mains powered then the L&N could be utilized to power the nest thermostats by connecting the other end of the cable to the 12v supply in the nest Hub, as said it is possible, it will be expensive, and you need someone who knows what they are doing, definitely not a DIY job.

    https://www.johnguest.com/speedfit/...iagram-Wireless-500x353-Z2105-413-0120_v2.pdf
     
  15. Braddels

    Braddels

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    I've had 2 people come round to install them and neither could do it. I already have the thermostats I need so the cheapest option now is to stick with Nest. The current thermostat are mains powered.
    Maybe I just need to get another person round to look at it again
     
  16. ianmcd

    ianmcd

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    That is good news for you as the existing mains cable can be utilised to power the nest Thermostats via the 12v output in the nest hubs, as long as the JG UFH actuators are 240v then of course it can be done, the nest is simply a switch, an intelligent one yes, but simply that a switch, post where you are and someone might be able to recommend someone that covers your area who is competent enough to do it for you
     
  17. Braddels

    Braddels

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    I'm in Nantwich, Cheshire. If anyone can recommend someone that would be great.

    I hope it can be done because the current thermostats aren’t user friendly and have been driving me mad for 3 years
     
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