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Tado X BDR91

Joined
14 Sep 2025
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United Kingdom
I'm looking at replacing a Honeywell BDR91 reciever/CM727 thermostat with a Tado X wireless stat. It's on a Vailant Ecofit pure 835 combi boiler.

I did put another post for a Hive, but have gone for Tado as I'm not sure the Hive with the hub, reciever and thermostat will work well in my house with layout, router position etc.

Can I confirm that the wiring is as follows in the BRD91-Tado according to the existing wiring:

N-N
L-L
A-CH Com
B-CH NO

Confirming that the linked wire between the two live terminals can be removed or is this specific to the boiler? Also, no wiring reconfiguration at the boiler is required.

Thanks in advance for any advice.
 

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N-N
L-L
A-CH Com
B-CH NO

Confirming that the linked wire between the two live terminals can be removed or is this specific to the boiler? Also, no wiring reconfiguration at the boiler is required.

Sounds good to me.

I love the way someone has linked the two L terminals together at the BDR91. The two L terminals are already linked internally and the second one is provided for the convenience of the installer for certain installations (yours isn't one of them).......except in this case, it's been an inconvenience to the installer who went to the trouble of adding a completely pointless link.
 
Thank you Stem. I did find it odd as they are effectively the same terminal, but thought it best to check. Thanks for confirming the wiring.
 

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