Nest install

[Jason smith]

Hi everyone hope you are all well im new to the forums and was wondering if any of you kind souls can help with the install of my nest 3rd Gen.

ĺ have a vaillant ecotec 28 combi boiler which already has a danfoss thermostat linked to it. The receiver which is a RX1 is powered by mains and the thermostat is running on batteries.

Iv included pics below and was just wondering if the install was as simple as both sets of L and N on the relevant terminal on the heatlink and the grey and black to terminal 2 and 3?

Any help is greatly appreciated.

 

[F355]

I've got exactly the same boiler and a Nest 3rd Gen so good news is it is possible and pretty easy to install. The biggest thing for me was double and triple checking everything before turning everything on because if you get it wrong you end up with a fried boiler PCB and an expensive plumber call out

On mine boiler I had 3 wires - L, N and 'call for heat' (230v). Because the terminals on the heat link are not big enough to accommodate two wires what I did was joined the L and N from the fused spur to the boiler L and N and tapped off for the Heat link L and N, then connected the 'call for heat' to 3rd terminal on the heat link.

Edit: Forgot I jumpered across from L for common

 

[Jason smith]

I was hoping i could get this done without having to open the boiler as for the earths do i just tape them off??

 

[F355]

You can definitely do it without opening the boiler. I did just to double check wiring but you can tell from the wiring going into your current stat.

Use a screw terminal block to connect your earths together.

 

[Jason smith]

Thanks for your help thats very much appreciated

 

[Adam_151]

It looks like your boiler is expecting a set of volt free contacts to be presented on the black and grey conductors, as oppsed to a switched live, I am not sure why the above poster has to put a link in, but I'd suggest you don't.

On your nest instructions you should have a wiring diagram. L and N are your live and neutral, so brown and blue, on each one you'll have one in the flex from the spur, and another one out to the boiler, now the above poster thinks you might have to do a joint to get them into the small terminals on the heatlink pcb, I can't comment on that, or how much space there will be available to do it. Earths should be connected to each other, so as above, use a single piece of connector block and put them together. Do not just tape them up!. 1= Satsified leave unconnected. 2= Common - Put your black here. 3=call for heat - Put grey here. If you want to be correct you should really put a bit of brown sleeving on the black and grey conductors.

T1 and T2 leave unconnected, unless you are running a cable between the heat link and the nest, as opposed to just plugging the nest in

 

[Jason smith]

Thank you adam for taking the time to reply i will try doing it that way.

 

[al090187]

Any updates on this? Did Adams way work Jason? I have a similar problem with my new nest purchase and a Vaillant boiler.

As yours, my existing Danfoss RX1 has the jumper across from L to Common, surely that means the system is set up already to use the switched live like F355 suggested, not the volt free that Adam is saying?