Help!? Replacing Old Sunvic stat w Nest Learning Thermostat 3rd Gen - Heat only system

Krissyboy87 · Dec 2, 2020

Evening all,

Apologies if this has been covered in another thread - I've never called upon a forum before! 😬

We're in the process of upgrading our old heat only boiler with a new Ideal Logic heat only boiler.

So, feels like an opportune time to upgrade our ancient (albeit reliable) Sunvic thermostat with an up to date smart thermostat - the Nest Learning 3rd Gen..

I've checked online for compatibility and it's not all that conclusive 🤷‍♂️ We've got solid core copper cables feeding the old stat, so that appears to be a tick, but I just want confidence that it will work with my system - words of confidence (or not) would be greatly appreciated!

I attach pics of our existing system and stat, and cables feeding it 👍

Aquarius · Dec 3, 2020

Good morning Krissyboy,

I don’t see a reason why it wouldn’t work. You have a y-plan system, the thermostat would need the 2 wires joining to the nest thermostat or disconnecting in the wiring center if you intend to use a usb lead for the nest thermostat? the heatlink would go where that black programmer is situated in the cylinder cupboard and wiring appears accessible. Should be straightforward enough.

Krissyboy87 · Dec 3, 2020

Aquarius said:
Good morning Krissyboy,

I don’t see a reason why it wouldn’t work. You have a y-plan system, the thermostat would need the 2 wires joining to the nest thermostat or disconnecting in the wiring center if you intend to use a usb lead for the nest thermostat? the heatlink would go where that black programmer is situated in the cylinder cupboard and wiring appears accessible. Should be straightforward enough.

Aquarius - season's greetings and thank you, that is really helpful!

I have just watched a video on wiring up the Nest to a "y-plan" system and now makes complete sense, lots of familiar parts etc! I am now satisfied that I can proceed to order the device.

Wishing you and yours a great Christmas!

Kris