Nest Thermostat and Baxi Combi 105E

[JORDAN CLARKE]

Hi i have wired the boiler to the nest as described. It was working fine however it is no longer controlling the heating the central heating is now no longer coming on. The hot water is. Do I have to link 1 and 2 on the boiler still?

 

[Dan Robinson]

Not working fine then is it?

 

[Christopher Tagg]

Did you get the central heating working? I’m going to try and install mine tomorrow on a baxi, what terminals did you use
Kind regards

 

[Grant Fraser]

Did you manage to get this working?

I've just followed the thread for my installation. The heatlink is up and running and the nest thermostat can communicate with the heatlink.

It doesn't control the heating at all though.

I have a Potterton boiler, but the wiring diagram is as per the original post.

I wired it exactly as per the low voltage diagram:
1 and 2 on Terminal to 2 and 3 on Heat Link
Live and Neutral from fused side of Terminal to Live and Neutral of of Heat link.

I also left the bridge from 1 and 2 on the terminal block in place.

I can here a switch clicking on and off when I change the temp of the nest, so I know it is communicating somewhat, but it must be missing a vital connection?


My boiler has a Mechanical Time Clock, which I currently use to control the heating with no thermostat.

Can I leave this in place and permanently on, as the Nest should control it?

At a bit of a loss...

 

[Johnmdc]

Remove the bridge between 1 and 2 and leave the clock on constant. The nest should now control your heating.

 

[Grant Fraser]

Remove the bridge between 1 and 2 and leave the clock on constant. The nest should now control your heating.

So I removed the bridge and the nest is now wired in 1&2 as the switch for the CH. Turning the thermostat up and down I can hear the nest clicking on and off, but it has no control over the CH being on or off.

The clock still ha still control of my CH and the nest a fancy temperature gauge

I've checked all the connections are good.

Not sure what else it could be

 

[Grant Fraser]

Further to my last post, I checked all the wiring again and all seems as it should.

So I got out the tester to make sure there was continuity within the wires, as I can hear the switch but that signal is clearly not getting to the boiler.

Wires are fine.

However, when off power 2 & 3 on the nest are connected.
And on power, regardless of the nest heatlink being on or off (manual mode) 2 & 3 are always connected.
From my understanding, when off, 1 & 2 should be connected (breaking the link for continious CH), and when on 2 & 3 connected, turning the CH on.

I tested that against the HW switch of 5 & 6, and that will control my CH on manual mode, obviosuly not on the auto mode with the nest thermostat.

So...

Do i have a faulty heat link?

If so, will they accept a warranty return, as I've done a manual installation?

 

[Johnmdc]

IT does sound as if the heat link is faulty.
You haven't linked L to 2 have you? If you have then remove the link.
If it is faulty then they should replace it regardless of who fitted it.

 

[Grant Fraser]

I did link L to 2 initially, then realised my mistake after finding this forum.

I'm 99% sure my wiring was correct, especially after confirming the switch on the HW side works.

I've removed and boxed it all back up and will email the company I purchased it from.

Thanks for all the help!