wire a nest thermostat up to a Logic+ combi boiler!

Discussion in 'Electricians' Talk' started by Tim Jolley, Jan 11, 2018.

  1. Tim Jolley

    Tim Jolley New Member

    I have wired in the nest and connected up the permanent live and neutral. What I am struggling with is the 'call for heat' wire.

    I am unable to work out where I need to wire it into. I have tried on the feed side where the red wire is looped round (room stat / timer) but it doesn't seem to be working and just stays on.

    Could someone advise me on this please - How do i disconnect the current thermostat and make sure the nest is now controlling the call for heat.

    Many thanks in advance.

    Attached Files:

  2. Bazza

    Bazza Well-Known Member

    You connect up the live and neutral supply to the nest

    Then you remove the red wire loop. Run two wires to the NEST, one goes to common, one goes to call for heat (2&3 on the NEST). That's It.

    As far as I can see your combi doesnt have a current thermostat. Where does this connect? Is that what those Wagos are for?
  3. mike booker

    mike booker New Member

    easier the use the opentherm connections that your boiler supports
  4. Tim Jolley

    Tim Jolley New Member

    The current thermostat connected in the first picture - the wires on the bottom.

    The wagos are what i have added with the three wires from the nest. The neutral goes into the neutral of the nest - the live into the live with a loop into port 2 and then final is into 3 (i presume the call for heat), which i havent wired anywhere yet.

    Are you saying that i need to remove the loop from the live to terminal 2 on the nest and wire that into the red loop on pic 2?

    Thanks very much.
  5. Bazza

    Bazza Well-Known Member

    Sorry, I do not understand. The wires at the bottom are the internal wires that go to the boilers control board. Or am i missing something?

    You need FOUR wires from the boiler to the NEST, plus an earth connection.
    You need to remove the loop. You need to supply two wires from the two terminals to the NEST. The wires go to termianls 2 and 3 on the Nest. DO NOT loop from live to terminal two! Does the instruction manual say to install a link to 230v? The boiler needs to see those two terminals that are marked ROOM STAT opening and closing. It is NOT expecting 230volts coming at it. Some boilers really do not like that. Some boilers use only 24v for that function, Some boilers will fry if you do that.

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