Nest Thermostat Gen 3 Dual Zone Install

[Deleted member 267285]

A&B is simply a switch mate (battery powered) they go to 2&3 on the heatlink, all the switch part does is send power to the Brown wire on the corrosponding Zone valve, the existing wiring will do the rest, but as said already the Heatlink needs an L&N supply to power it and if the OP wants to use T1 and T2 to power the thermostat , he /she will have to run a cable for that and supply and Earth to the Heat link

Thanks mate, I understand the switch part at a and b, could the existing not be used for T1 and T2 and alter at the wiring center though? Sort of how I thought in post #8?

 

[ianmcd]

Thanks mate, I understand the switch part at a and b, could the existing not be used for T1 and T2 and alter at the wiring center though? Sort of how I thought in post #8?

yes mate the wires in A&B could be used to power the nest thermostat, as long as they were totally disconnected at the wiring centre, and moved to the Heat link, at T1 and T2, and all new wiring will be required between the wiring centre and the heat link, not what the OP asked though, a bit above general DIY competence, if all the OP wants to do is use the existing 2 cores at A&B to power the thermostat then of course he can use that, but the Heat link will have to be wired into the wiring centre with 5 cores between the Wiring centre and the Heat link, as well as the two existing cores to power the thermostat

 

[MatthewM]

I need to do exactly this and I’m not sure how there is a misunderstanding. I included a link to a thread where someone had done this install.

 

[ianmcd]

I need to do exactly this and I’m not sure how there is a misunderstanding.

Because you wrote this

3. The L&N from the stats to be removed from wiring centre and wired to T1&T2 on the HL

Because the two wires in A&B are NOT L&N as you say, they are SWITCHING wires, there is no Neutral

 

[MatthewM]

Got it. That makes sense. It also raises the other point about power to the stat as if they are switching wires only will they power the stat?

 

[Deleted member 267285]

Got it. That makes sense. It also raises the other point about power to the stat as if they are switching wires only will they power the stat?

If they are taken to the heat link yes, otherwise they will be mains switching as Ian has pointed out

 

[MatthewM]

So I suppose the question then is aside from the terminology point Ian has made, was my initial post/plan correct please?