Nest heatlink wiring

1 Feb 2017
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Hopefully someone can help me out to make sure I'm using the correct wiring diagram for the 3rd generation nest.

Current setup - just a boiler, no thermostat.
One zone - Boiler heats rads and water all in one.

I have a condensing boiler with a live (black wire), a 2nd live (brown wire), a neutral (blue) and an earth. There is the 220 volt mains input brown, blue and earth.
This is currently connected to an apt clock timer
- 2 boiler live wires connected to live out on apt timer
- main live connected to live in on apt timer
- boiler and mains neutral wires connected to neutral on apt timer

I am connecting the nest up to just be able to switch on the heat remotely. Nothing else.

Based on the electrical diagram (combi boiler diagram attached)
Is it correct to connect

Mains live -> heatlink L
Mains neutral -> heatlink N

Boiler N -> heatlink N
Boiler L -> heatlink 3

Bridge a wire from heatlink L to heatlink 2

Would really appreciate if someone could confirm if this is this correct.


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Boilers come with many ways to be controlled, without information on the boiler and how it is wired at the moment it would be all too easy to give wrong information.

Has the boiler already got a thermostat or time clock, and what make and model is the boiler, given that you may get an answer.
The boiler is a gloworm flexicom 24hx condensing boiler. There is an apt clock timer on it. 3 ports on apt timer
Live in
Live out

Boiler live wires x 2 (brown and black) connected to Live out on apt timer
Mains live connected to live in on apt timer
Boiler neutral and mains neutral wire connected to apt neutral port of timer

No thermostat existing at the moment
Last edited:
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If the APT is a separate item from the boiler, this will need removing as the Nest will control both time and temperature functions.

You will then need to take the permanent live supply to the boilers N & L terminals respectively. This should also go to the N & L at the Nest Heatlink

Heatlink terminal 3 goes to the boiler terminal R (Switched Live 230 Vac)

Link the Heatlink terminals L and 2 together.

If you want to power the Nest Thermostat from the Heatlink connect the T1 and T2 terminals on the Heatlink to the corresponding terminals at the Thermostat, otherwise you can power the Thermostat from a separate plug in power supply.

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