Nest E Thermostat to replace ATAG One Controller

[markfrommanchester]

Hello

I wondered if anyone could advise me which cables go where, on the Heat Link for the Nest E Thermostat I have purchased.

The two cables shown are from behind the ATAG One Controller.

Thanks in advance

 

[Deleted member 120897]

Just C and No if it’s an on/off thermostat, usually doesn’t matter which way around as it’s a switch.

 

[markfrommanchester]

Just C and No if it’s an on/off thermostat, usually doesn’t matter which way around as it’s a switch.

So the Nest is just an off Thermostat? Sorry - if I'm being thick but I thought it was a bit smarter than that - but I suppose that's the software and it just controls when the heating is activated and to what temperature.

 

[markfrommanchester]

What I'm confused about is that the ATAG is Opentherm compatible.

Does that mean I need to somehow connect some other wires to the Heat Link?

 

[Deleted member 120897]

What I'm confused about is that the ATAG is Opentherm compatible.

Does that mean I need to somehow connect some other wires to the Heat Link?

I think the “smart” part refers to it learns certain aspects of your heating. If it’s opentherm compatible then you can wire both wires to OT1 and OT2, but if existing isn’t the same then they’ll need to be swapped at boiler end, bearing in mind, removing certain boiler covers that form part of the combustion circuit needs a competent person who is able to check for safety afterwards.

 

[markfrommanchester]

I think the “smart” part refers to it learns certain aspects of your heating. If it’s opentherm compatible then you can wire both wires to OT1 and OT2, but if existing isn’t the same then they’ll need to be swapped at boiler end, bearing in mind, removing certain boiler covers that form part of the combustion circuit needs a competent person who is able to check for safety afterwards.

Thanks - that got it working perfectly!

That was much easier than I anticipated except for the massive hole behind the old Thermostat and no spare wire to pull - which meant I ended up using 3M Velcro to stick the Heat Link in place as any holes I tried to drill shattered the exisiting plaster.

Anyway it works perfectly and controls my ATAG ic27 well.

Saved me £80 from a Nest Pro as I was confused initally when nothing worked with the original connections going to C and No.

Cheers

 

[Deleted member 120897]

If you want the Nest to be fitted more securely, you could carefully expose more wire further up the wall, secure to wall and trim the wires.