Installation of Nest 3rd Generation (Vaillant ecoTec Pro 28)

[derekocon]

I've got a Next 3rd generation and would like some guidance on the wiring for the Heat Link as I'm struggling to follow the wiring diagram in the manual.

Existing thermostat is Drayton Digistat SCR - wiring is shown in the attached picture.

Can someone tell me what wires goes where? Does the common from the SCR go to the common on the Heat Link? Do I need to join the L and N wires for the Heat Link in the same way as the SCR?

Also, the wiring diagram shows a link wire between Live and T2 on the Heat Link so I'm confused! Thanks.

 

[Echo the husky]

You're looking at the wrong diagram, if you connect it as per that diagram you will destroy your boiler pcb. Follow the Dry Contact diagram with black and grey in 2 and 3 on the nest. Ensure the earth wires are still connected together.

 

[derekocon]

Thanks so much for the guidance.

So just to confirm - I'll just connect the two Lives and two Neutrals together and run them into their respective terminals on the heat link, black wire to T2 and grey to T3. There's no earth terminal in the Heat Link so should I just join the two Earths and wrap some insulation tape around the join?

Thanks again.

 

[Echo the husky]

Yes. Join the earth wires in a connector block, there will be enough space for it under the cover. Don't cover it with tape as it will turn into a sticky mess.

 

[derekocon]

Got the thermostat fitted and working last night. Thanks again for your help.

 

[Guestiee]

Hi wondered if I could get some advise please. I have a vaillant eco tec pro 28 too. The connection from the boiler to the current thermostat heat link equivalent looks like the photo below. I only have 4 wires heading off to the boiler and it seems 3 of them are live neutral and earth, so I guess going to the mains connectors on the boiler. I am confused of how to connect the heat link to the current wiring as there is only one wire left based on my assumptions!

Any help would be great. Thanks.

20170908_222729

• Guestiee
• 9 Sep 2017

 

[Echo the husky]

The one wire left is the switched live to fire the boiler. The nest wiring is basically identical to what is currently connected to that salus receiver.

 

[Guestiee]

Lovely. So I just connect that to 3 on the nest? And loop the live into 2?

Thanks for your help

 

[Echo the husky]

Yes.

 

[Cunninghamster]

I've just registered to say thank you! This was exactly what I needed to install my Nest! Works like a dream!

 

[Diamond g]

Hi, would really appreciate any help on the install of the nest generation 3 to Vaillant EcoTEC pro 28. I understand that mains 230v is to be supplied to the neutral/live connections from the boiler to the nest. But where does the connections for 1/2/3 on nest get installed?

 

[Cheeros2465]

Hi, would really appreciate any help on the install of the nest generation 3 to Vaillant EcoTEC pro 28. I understand that mains 230v is to be supplied to the neutral/live connections from the boiler to the nest. But where does the connections for 1/2/3 on nest get installed?

I have the exact same question.
Please could someone help

Thank you

 

[Diamond g]

Figured it out. You need 3 wires from boiler. Live and neutral(from nest heat) get connected onto the live neutral on the boiler then the connector block next to the live neutral marked rt connect that onto terminal 3 on nest.
Then take a link of wire from the live terminal on the nest to terminal 2 on nest. (Must take off link at rt/24v terminal on boiler!!!!!!!!). Hope this helps. Works 100%

 

[claphamchris]

Figured it out. You need 3 wires from boiler. Live and neutral(from nest heat) get connected onto the live neutral on the boiler then the connector block next to the live neutral marked rt connect that onto terminal 3 on nest.
Then take a link of wire from the live terminal on the nest to terminal 2 on nest. (Must take off link at rt/24v terminal on boiler!!!!!!!!). Hope this helps. Works 100%

Do you have any pictures of how you’ve wired this up?

 

[Diamond g]

I will once I’m home you will need four core flex