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Nest 3rd Gen to replace Drayton LP241 , With no junction box

Discussion in 'Plumbing and Central Heating' started by jackalg1, 29 Dec 2018.

  1. jackalg1

    jackalg1

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    Hello

    I want to replace a Drayton LP241 programmer with a Nest 3rd Gen , but ive noticed everything in wired directly into the LP241 ? . The Zone valve, Grunfoss Heating pump, and the Hot water tank cylinder stat ,roomstat etc . Im pretty confused as in my last house i only had half a dozen wires coming straight from a junction box etc, so it was pretty easy to install

    many thanks
     

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  2. ianmcd

    ianmcd

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    What a blooody mess, get someone in to fit a wiring centre and tidy that disgrace up, you will not cram all those wires into a nest receiver
     
  3. Dan Robinson

    Dan Robinson

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    A leaking mess too by the look of things.
     
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  4. ianmcd

    ianmcd

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    But its only 240v wiring for the cyl stat that is laying in the leaking water so does that really count ? it is wiring for a water tank is it not :LOL::LOL::LOL:
     
  5. jackalg1

    jackalg1

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    Nothing is leaking now the 3 pos valve was replaced before I moved in
     
  6. ianmcd

    ianmcd

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    Looks like the gate valve (Red handled valve in your pic) is leaking
     
  7. stem

    stem

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    You may find that buried in the wall behind the Drayton is a back box that has been used as a junction box.

    The Heat link replaces the Danfoss so they can be exchanged quite easily. The only problem you may encounter is if there are a lot of wires in the Drayton and not enough room to terminate them all in the Heat link. I which case you may find it easier to replace the Drayton with a junction box and then just wire single conductors from that to the Heat link terminals.

    The Drayton wiring terminals have the following functions:

    LP241.JPG

    The existing wires are transferred from the terminals of the Drayton, to the Nest Heat link terminals that have exactly the same function.

    Nest.JPG

    Neutral, Live & Earth are straightforward
    Drayton (1) Hot Water off = Heat link (4) Hot Water Satisfied
    Drayton (3) Hot Water on = Heat link (6) Hot water Call for Heat
    Drayton (4) Central Heating on = Heat link (3) Heating Call for Heat
    Then terminals (L) (2) & (5) need to be electrically connected together

    Don't worry if there aren't wires in every terminal, you will only need to use the wires that are present now.

    The Nest Thermostat needs a 12v supply and can be powered either by using a separate plug in power supply, or by connecting terminals T1 & T2 of the Thermostat to the corresponding terminals at the Heat link.

    Finally any existing room thermostat needs to be decommissioned, it can't just be disconnected otherwise the heating wiring would be permanently 'open circuit' and the heating would not operate. This is done by finding the origin of the thermostat cable, disconnecting it completely and then inserting a link between the terminals where the two thermostat live switching wires have just been removed from, so that they are electrically connected to complete the circuit. Alternatively as a temporary measure setting the existing room thermostat to maximum / permanently on, will prevent it interfering with the operation of the Nest
     
  8. DIYnot Local

    DIYnot Local

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