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