Installing bdr91 Instead of standard stat

[Hawken82]

Hi all thank you for your help in advance.

When I got a new boiler installed they put the stat next to the boiler as in images above, this happened due to the fact that they couldn't find the wiring to the stat in my lounge and I said I'd like a wireless stat like nest in the future so they put the stat there. I bought honey well wireless stat cheap the relay is in a photo above the combo boiler is a back eco.
They have the wires going from the maiins switch to the boiler back to the stat.

How do I wire in the bdr91?




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[stem]

Hello Hawken82 and welcome to the forum.

Remove the existing shabby thermostat wiring. (What's with so much tape?)

Then:

Connect the boiler '230v Line Out' (2) terminal, to 'A' on the BDR91
Connect the boiler 'Switched Live In' (1) terminal, to 'B' on the BDR91

You also need a mains supply to power the BDR91, so:

Connect the BDR91 'L' (it doesn't matter which 'L' terminal you use) to the 'L' at the boiler along with the existing wire already there
Connect the BDR91 'N' to the 'N' at the boiler along with the existing wire already there

 

[Hawken82]

Well I guess the tape is there so they new which one went to live and neutral.

 

[stem]

You are absolutely right of course. My comment was not relating to why it was there, but rather why there was 'so much' of it. It should really have Brown and Blue sleeving, not Red and Black tape. But this is what often happens when the guy who fits the boiler does the wiring, instead of getting an electrician in to do it properly.

 

[Hawken82]

So there's no earth on the bdr91. Can I use the earth wire that is currently going to the earth in the stat for the live to live and mark it up for future reference

 

[Hawken82]

That sounds like a dumb question now I've asked it but just so I'm sure.

 

[Hawken82]

Ye it was the boiler guys that fitted it.

 

[stem]

So there's no earth on the bdr91. Can I use the earth wire that is currently going to the earth in the stat for the live to live and mark it up for future reference

It's not good practice to do so. I wouldn't, and so I'm not going to say you should use it. But it is done frequently.

There is an alternative way to wire it using one less wire. Instead of running a separate wire from the boiler '230v Line Out' to to 'A' on the BDR91, you could simply link the spare 'L' terminal on the BDR91 to 'A' instead

 

[Hawken82]

Ok so put connect a wire from the live on the boiler to L on the bdr91 then bridge wire to A, and not worry about the 230v line out.

 

[stem]

That sounds about right. Here's a sketch

 

[stem]

Or this way, which you wouldn't need to get two live wires in the same boiler terminal.

 

[Hawken82]

That sounds about right. Here's a sketch

View attachment 112134

Thank you so much all done and sorted now. I had an electrician that came and gave me a quote of £80. he didn't turn up to do it and never even called or text to say sorry.

You have really helped me out. If you lived where I am if get you a drink in. People on forums like this are a massive help.
Thanks again

 

[stem]

You are welcome. Glad to be able to help, and thanks for the feedback, it helps any others that may come across this thread looking for help with a similar project.