Nest 3the generation

[Piet Knevels]

Hi,

I have bought a Nest 3the generation and i'm struggeling to connect it to the Vaillant 286. The Vaillant is new so no old thermostat needs to be replaced. I have opened the Vaillant and to my surprise there were much more connection possibilities then expected. To which should i connect the heatlink? And to be sure in which of the heatlink possibilities should i connect the Vaillant?

I thought to connect the Vaillant: BUS - and + to the OpenTherm on the Vaillant?

The Heatlink does not need to receive power from the Vaillant, as this will be directly connected to the electricity.

 

[stem]

I don't have experience with using OpenTherm (I believe that there maybe some issues with it in the UK. However, I see that you are in Belgium, so maybe someone else will be able to advise) but you can connect the Heatlink to the Vaillant by removing the red link between the boiler terminals RT and 24V which are provided for a remote thermostat (RT) and connecting them to terminals 2 and 3 at the Heatlink. It doesn't matter which way around they go.

The Nest thermostat can be powered by connecting it to the Heatlink T1 and T2 terminals, or by using a separate plug in power supply.

Then you just need 230V to power the Heatlink, which should be provided via the same 'fused connection unit' supplying the boiler. You can pick it up from the FCU, or the boiler permanent L & N terminals. Here in the UK, the Heatlink should not have a separate supply to the boiler, so that anyone working on the system and thinks that he has turned it off doesn't get an electric shock. Maybe this is different in Belgium.

 

[Dan Robinson]

You'll need the vr33 to make the OpenTherm work on the bus terminals.

 

[Piet Knevels]

Thanks!! I will try it tomorrow and let you know if it works!