Nest thermostat.

[davygravy]

Hi, been given a nest 3rd generation thermostat, can anyone give some advice on wiring the link up, this will replace a Honeywell relay, the nest will be connected wirelessly, I have 2 wires coming out of the relay as pictured, where do they go in the new nest link, regards

 

[Dan Robinson]

Have you tried looking at the wiring diagrams?

These threads are getting ridiculous.

 

[Dan Robinson]

Or even using the forum search function?

 

[jackthom]

I agree Dan but nevertheless here goes again..

The leads now in A & B in the Honeywell go into 2 & 3 in the Heatlink.
Of course the Live and Neutral are also required to power the Heatlink.

 

[Chrise88]

Just to add to this. I have this set up at home. Would you still need to link L to 2 or just A and B to 2 and 3. Thanks in advance.

 

[flameport]

Would you still need to link L to 2

Some systems may require that. Others do not.
If it's required and not done, it won't work.
If it's done when not required, it may destroy the boiler PCB, which will cost £100s to replace.

The solution with any of these devices is to read the boiler instructions and confirm where wires are connected to determine what is required.

 

[Chrise88]

Some systems may require that. Others do not.
If it's required and not done, it won't work.
If it's done when not required, it may destroy the boiler PCB, which will cost £100s to replace.

The solution with any of these devices is to read the boiler instructions and confirm where wires are connected to determine what is required.

Thank you I will dig out my boiler manual and have a look.

 

[jackthom]

Your BDR91 in the picture is set up without a Live link so the Heatlink should be wired the same way.

Adding a wire from Live to terminal 2 is unnecessary and could even cause serious damage to the boiler.