Stem,
Thank you for you excellent advice! I was confused by the wiring colours. I have now followed your instructions and everything is working superbly. Your help is much appreciated, thanks for taking the time.
I would appreciate it if anyone could help me with this.... currently I have a BDR91 attached to a Vaillant EcoTech Plus, I am trying to replace it with a Tado Extension Kit.
The wiring inside of the BDR91 has live and neutral wires, x2. I have attached the neutral and live wire from the left...