DIY Doctor UK DIY Forums

I'm installing a Nest Gen 3 as a room thermostat on a boiler only system (no AC).

I'm not planning to use the Heat Link as our Hot Water only comes on twice a day via the timer by the boiler, and works fine.

So this is controlling only radiators. The old stat (a Floureon HY03) has 4 numbered terminals which doesn't really help me.

We're on the old school wiring colours red, blue, yellow and yellow/green.

Can anyone tell me which connections on the Nest I need for which colour?

Hi Chatman,
On the heat link you will need to put the supply in on the N and L terminals, fit a link across from L to terminal 2,
T1 and T2 go to the display.
The issue will be identifying the existing wiring and whilst there is a convention eg L is red, this is by no means certain. You will have to get someone in who can trace the wires to establish what they do.
Regards S