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TR2 thermostat wires - which is the neutral?

Discussion in 'Plumbing and Central Heating' started by Sparkeee, 10 Oct 2021.

  1. Sparkeee

    Sparkeee

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    I am just looking for some simple information which I can't find online anywhere. I have an old RD532i boiler and TR2 thermostat. The wires between them are labelled F, 3 and 4. Can anyone tell me which of those three wires are the neutral, the live and the switched live? (I think that's what they actually are)
     
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  3. CBW

    CBW

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    You might not actually have a neutral, it could be low voltage. A photo may be useful.
     
  4. RandomGrinch

    RandomGrinch

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    Hi,
    Are you trying to find out what the existing connections are between the two, or are you trying to connect them together?
    If they are already connected (and if this is your model!), The wiring connections are listed on p.8 and p.22

    Edit:
    TR2's are low voltage only and should never be connected to the mains, hence the F, 3 and 4 labels
     

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    Last edited: 10 Oct 2021
  5. Sparkeee

    Sparkeee

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    Thanks for your replies. I am not connecting them together. I just need to identify which wire is which. I know the TR2 is a low voltage device. Here is a photo of the connections to the boiler.
     

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  6. RandomGrinch

    RandomGrinch

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    I may be mistaken, but it sounds as if you are expecting the TR2 to behave as a simple thermostat, i.e. have a live, neutral and switched live (albeit having a low voltage equivalent).

    Because the TR2 is fully integrated into the boiler, the wiring may (although I am unsure) be 0V, +V and Data.

    It does not behave in the same way as a simple thermostat.

    There is some further info here:
    https://www.homeownershub.com/uk-diy/worcester-bosch-tr2-room-stat-reverse-engineered-428844-.htm

    Why do you want to know what the wires do?
     
  7. Sparkeee

    Sparkeee

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    It's to remove the TR2. And a pair of the wires need to be bridged. Believe me I have read all the articles and that one about the reverse engineering isn't clear. It talks about finding the resistance between two pairs of the 3 wires but without making it clear which is which.
     
  8. RandomGrinch

    RandomGrinch

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    I'm sorry, I uploaded the wrong manual for the boiler model you have.
    Having read that, may I suggest you do the same?
    All the information you need is there.

    The article I linked to, did state which connections should be made to where.
    However, this article is only relevant where the boiler has no means of external control and you wish to bypass the TR2.
     
    Last edited: 11 Oct 2021
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