26 Nov 2017
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United Kingdom

I'm looking for some advice on a new Nest V3 Installation for hot water and heating control.

I currently have a Y plan system with the following components:

- Boiler - Ideal Classic FF350 in the utility room.
- Programmer - Danfoss FP715 (below the boiler).
- Danfoss - thermostat in the corridor.
- Hot water tank upstairs airing cupboard with Grundfos Pump UPS2 15-50/60 and single Drayton Mid Position Actuator and Danfoss WB12 wiring centre / junction box.

I'm planning on plugging in the Nest V3 on a stand so don't require physical installation of that part. I just need to wire up the heatlink itself for hot water and heating control. I would like to wire this to the Danfoss wiring centre.

I've included some images of the instructions etc. Any assistance would be appreciated.

Is the Danfoss WB12 wiring centre a standard wiring configuration? Is anyone able to advise on connecting the Nest Heat link?




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The Danfoss FP715 programmer is wired as below:


From this you can identify what the wires do, and find the corresponding terminals at the Heatlink that have the same function.

For example 'DHW On' (terminal 3) at the FP715 = 'Hot water call for heat' (terminal 6) at the Heatlink, and 'HTG On' (terminal 4) at the FP715 = 'Heating call for heat' (terminal 3) at the Heatlink.

Terminal 2 at the FP715 won't have a wire connected, so don't worry about this. This wiring that is presently at the FP715, needs to be redirected to the Nest Heatlink function for function.

After you have identified the wires, mark them carefully, and move them from the FP715 to the terminals at the Heatlink that have the same function.

If there is more than one wire in some of the terminals, they will need to be moved together.

Once all of the wires are moved across, insert wires to link together the Heatlink terminals Live (L) and the two Commons (2) and (5)

You don't mention any existing room thermostat. If there is one, it will need to be decommissioned to prevent it will overriding the Nest, and it can't just be disconnected, otherwise the heating wiring will be 'open circuit' and not operate. This can be done by tracing the wires back from the thermostat and finding where they originate from. Then disconnect them at their origin, and the two terminals where the switching wires came from should be joined together. Post back with details of the thermostat if you need anymore help.

It's much more difficult to wire it into the wiring centre. Almost every installation is different depending on the personal choices of the original installer, the layout of your house etc., If you want to trace each of the wires from the existing programmer back to the wiring centre, mark each one up and the run new wires to the Nest you can. But I wouldn't recommend it unless you are extremely competent with wiring and have a full understanding of what each wire in your wiring centre actually does.
Last edited:

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