1st Gen Nest thermostat with Vokera Boiler

[Shezy]

Hi All

I need some help with my 1st Gen Nest thermostat installation. I bought it ages ago but wasn't able to install it. Winter is approaching so I think this is the time to go-ahead with the install.

Some info about my setup:

I have a Vokera Unica HE combi boiler. It's manual can be found at following link:

http://cdn0.vokera.co.uk/wp-content/uploads/2009/04/unica-he-installation-and-servicing-manual.pdf

It would have been a simple install if I was to swap an old thermostat but for some strange reason previous owner of our house never attached a thermostat to the boiler. He was turning the heating ON and OFF directly from the boiler. So I'll need to connect the thermostat to the boiler directly using a suitable cable. I'm planning to open the boiler over the weekend to have a look at the wiring options available.

I've chatted with Nest support and they have advised to go for a Pro install which I think is quite expensive.

I've also spoken to Vokera and their support is meant for professional installers and I didn't understand most of instructions they gave me. Their engineer told me that:

There are total four wires: Brown, Blue, Red and Black

If thermostat is volt free connect Red and Black
If it’s single wire connect only Red
There’s a loop above Red and Black which need to be removed.

Keeping above in view, I would appreciate if someone can suggest:

1) What will be the current (in volts) on the live where thermostat is to be connected (point 3 in top row from left to right) on M5. As far as I know 1st Gen Nest can't be connected to 230 V.
2) Is a standard Twin & earth cable would be fine for connecting the thermostat to boiler
3) Where would I connect the Neutral and Earth if above cable is to be used.
4) Would I need to connect Call for Heat as well. If yes, where will it be connected?

I do DIY quite often but have never done this kinda install before so any guidance would be extremely helpful. Would need suggestions on how to connect it and what type of cable to use.

Thanks in advance.

 

[stem]

The Neutral and Live supply to the Heatlink connect to the same terminals as the incoming 230V mains Neutral and Live supply to the boiler.

Remove the link marked 'room thermostat' and connect the two terminals where the link went to terminals to 2 and 3 at the Heatlink, it doesn't matter which way around they go.

A single 4 core + earth (if your version of the Heatlink has an earth connection) heat resistant cable can be used to connect the Heatlink to the boiler. Click here for an example.

You can power the remote Nest thermostat by connecting it to the heatlink terminals T1 & T2, or using a separate plug in power supply.

 

[Shezy]

Hey Stem

Thanks for the prompt suggestion

Unfortunately I have 1st Gen Nest so there's no Heat Link with it. I do have the following Wiring Base:

Would you be kind enough o suggest the connections for this please

Thanks

 

[stem]

Sorry then I can't help, you. I have never seen one like this, only the versions with a Heatlink, and so I don't have a wiring diagram to know what each of the terminals does. I suspect that it may only be suitable for 24v operation and the wires in the diagram for your boiler are 230V so you might not even be able to use it. Hopefully someone who has experience of it will be along shortly to assist.

 

[Shezy]

Thanks Stem.

Appreciate your help

 

[muggles]

Can you repost the picture of your Nest please @Shezy I can't see it

 

[Shezy]

 

[Shezy]

Hi @muggles

Can you the above one

 

[muggles]

Yes I can thanks, and I'm afraid I can confirm stem's suspicions. This is the American version and is not compatible with UK heating systems, you've been sold a dud

 

[Shezy]

Really

That's too bad. I got it from ebay last week. Seller was from UK as it was delivered in couple of days. He didn't mention anything this being Us version and no compatibility with UK systems

 

[Shezy]

I've opened a return request with seller

 

[Shezy]

The Neutral and Live supply to the Heatlink connect to the same terminals as the incoming 230V mains Neutral and Live supply to the boiler.

Remove the link marked 'room thermostat' and connect the two terminals where the link went to terminals to 2 and 3 at the Heatlink, it doesn't matter which way around they go.

A single 4 core + earth (if your version of the Heatlink has an earth connection) heat resistant cable can be used to connect the Heatlink to the boiler. Click here for an example.

You can power the remote Nest thermostat by connecting it to the heatlink terminals T1 & T2, or using a separate plug in power supply.

Hi Stem

Thanks once again for your help.

I got the 2nd Gen UK version and installed it yesterday using your advice.
It's working perfectly fine.

One more small thing.
Can you kindly advise a suitable cable to connect T1-T2 links from Heat Link to Thermostat Base for power.

Much appreciated

 

[stem]

I generally use 0.75mm or 0.5mm 2 Core PVC Flex. But if it is an exposed location such as inside a garage or somewhere else where it needs clipping, then I have used 1mm twin and earth, and cut the earth off.

 

[Shezy]

Thanks mate