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Replacing Horstmann Channel XL thermostat with Nest

Discussion in 'Plumbing and Central Heating' started by Joey-D, 29 Jan 2021.

  1. Joey-D

    Joey-D

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    Hi

    I am attempting to replace a Horstmann Channel XL plus with a Nest thermostat.
    I have not been able to find a wiring diagram for this particular Horstmann model. I can find the diagram for the series 2 but that appears to be different.
    I was expecting to see a wires as below:
    Earth (empty)
    Neutral
    Live
    1 - heating on signal
    2 - live
    3 - heating off signal
    4 - hot water on
    5 - live
    6 - hot water off (this position is empty)

    There is a remote thermostat controller wired in as well but I was ignoring this and planning on just removing it.

    Can I assume that as position 6 is empty my system doesn’t need a hot water off signal?

    I have attached a photo of the current set up.


    http://horstmann.securemeters.com/files/2514/6916/4123/installer_guide_H37XL-ISeries21.pdf
     

    Attached Files:

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  3. MJN

    MJN

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    Are you sure the CH and HW aren't the wrong way round there? This manual for the Series 2 suggests it is, and that 123 are for HW and 456 for CH.

    Not if the diagram I've linked to matches your setup.

    Always a worry to see the CPC used as a switched live, but at least they marked it (not that that makes it acceptable, but it could be worse!). ;)
     
    Last edited: 29 Jan 2021
  4. Joey-D

    Joey-D

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    Thanks. That makes more sense now.
    So the way I see it the yellow and wire joined in the terminal block (to a black wire) should go to position 6 but is taken off to a feed from the remote thermostat.
     
  5. ianmcd

    ianmcd

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    your origional set up is not wired correctly , there should be a link between L&2&5 you have a link between L&2 but a different wire in 5 that is wrong
     
  6. Joey-D

    Joey-D

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    The wire into 5 comes via the remote thermostat. Not how I would have wired it but it works.
     
  7. ianmcd

    ianmcd

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    Position 6 is CH off, you dont need a wire in there, you do need a wire in HW off existing terminal 1, you have a Y plan system, plenty of wiring diagrams online
     
  8. MJN

    MJN

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    Yes, it would indeed work - the electrons don't really care whether the timer or thermostat comes first in a series circuit! :)
     
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