Replace Horstmann Centaurstat 7 Controller with new SMART option

[Mushy1]

I want to upgrade my current Horstmann Centaurstat 7 heating controller with a new smart option. I have looked at several such as the Nest, Hive, Honeywell, Tado, and Netatmo but not sure which one is best and how they can be connected. I'm currently leaning towards the Nest but the wiring diagrams are not compatible with my current setup so any help on this would be very much appreciated. I have created an image of my wiring configuration in hope it helps with my question. Thank you

 

[CBW]

Ok, not the best wiring diagram. Where is the Horstmann located?

Looks like you have a y-plan, so yes it’s compatible with your setup.​

 

[Mushy1]

Thanks for your response and apologies for my attempt at a wiring diagram. The Horstmann is located in the hallway. How would I wire the existing wires to the nest?

 

[CBW]

It looks like your centaurstat doesn’t have a LNE, so the Nest, or whatever you’re using would be best placed near the wiring center. You could use the room thermostat Live and switched for T1 and T2.

 

[ianmcd]

You could use the room thermostat Live and switched for T1 and T2.

If you are going to do that you will also require and earth at the heat-link