Honeywell R6660D to Nest 3rd gen

[soopercerial]

Hi, I want to upgrade my Honeywell R6660D to a Nest 3rd gen.

I have looked over the forum, but my thermostat seems to have more wires than in the other pictures.

Could someone please tell me which ports the wires should go from my current thermostat to the Nest Heat Link?

Thank you very much.

 

[RandomGrinch]

Your R6660D has cables daisy chained in and out - these connections will have to be replicated on the Heatlink.
This can be tricky as the Heatlink terminals are quite small.

The two browns in the L terminals on the R6660 go into the L on the Heatlink.
The grey and black with blue sleeve in N, go to N on the Heatlink.
The two Green/Yellow wires in the earth terminal must remain connected together and can go to the earth terminal on the Heatlink.

That leaves the wires in terminals A and B, these connect to terminals 2 and 3 on the Heatlink.

 

[soopercerial]

Thank you very much.

I am used to wiring plug sockets but this was a bit above me haha.

I appreciate your reply

 

[Michael603]

Hi, I have a similar query regarding the same istallation although I seem to have less cables to contend with.

From the attached photo, I have one 4-core cable entering the R6660D from a fused (3 amp) switch.
These lead into terminals N + L and also terminal B with a red "loop" joining terminals L (second one) and A.

Are these wires easily transferable into the Nest 3rd Gen heatlink or am just looking to make it harder than it should be?

Any help would be appreciated.

 

[RandomGrinch]

Are these wires easily transferable into the Nest 3rd Gen heatlink or am just looking to make it harder than it should be?

It should be straightforward.
With the power safely isolated...

The Blue wire in N of the R6660D, would go to N, on the Nest Heatlink.
Brown wire in L, to L
Black wire in B, to terminal 3 on the Heatlink (call-for-heat)
Use the Red link wire to connect L to terminal 2 (Common) on the Heatlink.

If you intend to use terminals T1 and T2 to power the Nest thermostat, the flex will need to be stripped back, to allow the green/yellow wire to be connected into the earth terminal on the Heatlink.

 

[Michael603]

Thanks for your quick reply. My Nest thermostat will be powered by its own power cable that I bought separately.

Once again, thank you for your input.