Issue Replacing Honeywell BDR91 Receiver with Tado Extension Kit

[StanWardle]

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 hand side of the picture to the L & N on the Extension Kit backplate. The other two wires I have connected to 1 and 2 on the backplate. Can anyone advise if this is correct? The extension kit appears to be connected to the thermostat remotely, the app suggests all is working ok. But the boiler does not seem to be coming off and on as per instructions sent.

 

[stem]

The BDR Box is removed and:

The wire in BDR N goes to Tado Extension Box N
The wire in BDR L goes to Tado Extension Box L
The wire in BDR A goes to Tado Extension Box 1 (COM)
The wire in BDR B goes to Tado Extension Box 4 (NO)

IMPORTANT: Make sure that the Tado Extension Box jumper is in Position 1. (Potential Free) Otherwise you may damage your boiler.

If there is some sort of time control for the central heating somewhere else that you haven't mentioned, that should be set to be permanently 'on' 24/7 Otherwise it will interfere with the Tado.

Edit: The wire colours chosen by the installer do not always reflect their true use. In your case, the blue wire in BDR B for example is definitely not being used as a neutral wire.

 

[StanWardle]

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.