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Install of nest 3rd gen.

Discussion in 'Plumbing and Central Heating' started by peterm_sc, 30 Dec 2018.

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  1. peterm_sc

    peterm_sc

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    this is what we have at the moment.

    in the utility room we have
    • a ferrolli boiler
    • a siemens rwb27 controller

    up stairs
    • there is a seperate on off switch for an immersion which provides hot water only


    but when the siemens is switched on, it heats the house and also heats the water
    the switch upstairs is for water only

    we do not appear to have a thermostat, our heating is manual, and turned on/off by us or by a timer system.

    i have attempted to install the nest, i have made the error of thinking it would be simpler than it is..

    https://imgur.com/a/ljaaKsI
    https://imgur.com/a/xTlzyPA
    https://imgur.com/a/JGaO07W

    As you can see, there is a L & N
    the L is looped through to 2, to enable 240v system
    there is a second wire connected to the 2 ( aside from the loop from L )
    there are 2 wires in the 4 position, one is brown and one is black

    my understanding is that the 2 position is call for heat off
    and the 4 is call for heat on .

    but.
    if you look at the nest diagrams, they use different terms

    https://imgur.com/a/0zkWfng

    so
    can someone help me with the following.

    the wiring for the nest
    can someone explain the ch off ch on thing.
    is call for heat off - an open system ( an open circuit)
    is call for heat on - a closed circuit, thus engaging the boiler

    the two wires in the 4 position, is one of them a controlling wire for the immersion system, would it be possible to wire this into a different position in the nest, so that we could control our hot water from the app
    if so, would it be a case of identifying the cicuit for the boiler i.e ch on ch off , and then the remaining wire must be for the immersion.

    thank you.
     
  2. peterm_sc

    peterm_sc

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    no-one?
     
  3. JohnD

    JohnD

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