Replace Honeywell BDR91 with 3rd gen Nest heat link

[philahilla]

Hi

We've got an Ideal HE 35 boiler going into a Honeywell BDR91 wireless relay box and looking to swap this out with a new 3rd gen Nest heat link. I've taken the cover off the relay box and can't figure out the wiring and how it would go into the heat link. Was wondering if I could get a bit of guidance?

IMG_1109

• philahilla
• 6 Nov 2016

Power supply to wireless relay box

This is what it looks like at the minute:

IMG_1110

• philahilla
• 6 Nov 2016

Wireless relay box wiring

And I want it to go into this:

IMG_1111

• philahilla
• 6 Nov 2016

Heat link wiring guide

Photos aren't brilliant so this is how it's wired up

Black wire from power supply:

Live wire goes to middle L
Neutral wire goes into choc box one side and into N from other side
Earth goes no where

White wire from boiler:

Black (neutral?) wire goes to A
Grey wire goes to B
Live wire goes to middle L
Blue (neutral?) wire goes into choc box one side and into N other side (as above)
There's a Live wire "loop" going from middle L to right L
Earth goes no where

I don't know why there's both a black and blue wire as I thought they were both neutral?

Any help much appreciated

Many thanks

Phil

 

[Dan Robinson]

Black (neutral?) wire goes to A

I don't know why there's both a black and blue wire as I thought they were both neutral?

Do you think that with this level of electrical knowledge you should be attempting this ?

The wiring diagrams on the bdr and heat link are pretty clear .

 

[Echo the husky]

Who crushed all the wiring in like that? The insulation is damaged and can't be used again in the condition it is in. Also the earths are not connected! There is also a link between the 2 Ls which isn't required as the link is already made internally.

 

[muggles]

There is also a link between the 2 Ls which isn't required as the link is already made internally.

No it isn't

 

[Echo the husky]

It is on all the ones I've ever fitted!

 

[muggles]

Ah, sorry, didn't look at it properly, yes the two L terminals are internally linked, L to A isn't. It's been a long day!

 

[Echo the husky]

I was just about to post a pic of the installation manual showing the internal link! So here it is.

 

[D_Hailsham]

Black wire from power supply:

Live wire goes to middle L : Connect to L
Neutral wire goes into choc box one side and into N from other side: Connect this one to N
Leave both blue neutral wires in other side of terminal block
Earth goes nowhere: connect to earth terminal

White wire from boiler:

Black (neutral?) wire goes to A: This not a neutral - connect to 2
Grey wire goes to B: Connect to 3
Live wire goes to middle L: Connect to L
Blue (neutral?) wire goes into choc box one side and into N other side (as above): See black wire above
There's a Live wire "loop" going from middle L to right L: Ignore it
Earth goes nowhere: Connect to earth

 

[Echo the husky]

I would also want to check that the earth wires at the other ends of the 2 cables are also properly connected.

 

[D_Hailsham]

I would also want to check that the earth wires at the other ends of the 2 cables are also properly connected.

Even if they are, as currently wired the boiler is not properly earthed!