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Replacing rf thermostat with nest gen 3 thermostat

Discussion in 'Plumbing and Central Heating' started by CitizenV, 25 Mar 2019.

  1. CitizenV

    CitizenV

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    So I decided to swap my old Salus RT500RF thermostat with a new Nest gen 3 thermostat. I thought it would be case of swapping the boxes over but I’m not sure the wiring is correct or if I’ve got the wiring correct. The boiler it’s connected to is a Vokera by Riello easy heat plus 29 c The old salus box is connected to the CN5 circuit that much I know but I’m having trouble understanding if I’ve got the right wires in the correct ports on the heat link, because the back of the salus box is different to heat link. I’ve included pics of the wiring on the heat link and the wires on CN5 circuit
     

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  2. stem

    stem

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    You don't make mention of any hot water control, so I assume that your Vokera is a combi boiler and so doesn't require connections to the Heatlink hot water control.

    The Salus RT500RF receiver wiring terminals are:

    Salus.JPG

    The existing wires, (including any link between terminals, but only if one is already present) that are presently connected to the Salus receiver are simply rerouted to the Nest Heat link terminals that have the same function:

    Nest.jpeg
    So:

    Salus 1 NO = Nest 3 Heating call for heat
    Salus 2 COM = Nest 2 Heating Common
    Salus 3 L = Nest L
    Salus 4 N = Nest N

    The Nest thermostat needs 12v to operate and it can get this either by connecting its T1 & T2 terminals to T1 & T2 at the Heat link, or by using a separate plug in power supply. If you do use T1 & T2 to power the thermostat, then an earth connection should be made to the Heat link earth terminal.

    If your boiler has any separate time control it should be set to be permanently on 24/7, but this would have been the case with the Salus already anyway.
     
  3. ianmcd

    ianmcd

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    you have wired that wrong in your pic of the nest take the wire out of terminal 1 and put it in 3, you will read posts on here about installing links DO NOT do that with your boiler
     
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