Nest 3rd Gen Theromostat Issues

[James Wheeler]

Hi all, I am new to the forum and have been searching for advice on wiring the Nest to a Vaillent TurboMax. I originally installed, myself, a wireless thermostat a few years back the Honeywell CM700. This has worked perfectly but now technology is evolving I am looking to swap it out for the Nest.

I have found the below advice which I have followed and am not able to see the boiler heat up.

https://www.diynot.com/diy/threads/installing-a-nest-to-a-vaillant-turbomax.425632/

I hear the switch going on and off in the Heat Link but the boiler doesn't do anything so I am guessing some wiring is incorrect.

I have wired using the same wires I had for the Honeywell:

boiler 3 to Heatlink L and created a loop to 2.
boiler 4 to Heatlink 3.
boiler 5 to Heatlink N.

Now previously L and N where wired to the Honeywell L and N so I have removed this and reused it for the 5 to N.

Does anyone see anything wrong with what I have done?

 

[stem]

That sounds right.

Boiler 3 = Live to Heatlink
Boiler 5 = Neutral to Heatlink
Boiler 4 = Switched live from Heatlink terminal 3

Link Heatlink terminals L and 2

So other things to consider.

1.Check the Heatlink wiring terminals carefully. They are a bit fiddly and it can be easy to clamp the insulation and not the conductor. If the Heatlink is clicking then the L & N would appear OK, so check the switched live.

2. If the boiler has an inbuilt timer, then that would need to be set to be permanently 'on' 24/7.

 

[James Wheeler]

Thanks I shouldn’t have gave up so easily.. the nest is now working perfectly must have been a wire not fully making contact

 

[stem]

That's usually the case. It happens quite a bit. They aren't the easiest things to wire up. Glad it's working and thanks for the update it might help others that find this thread and have the same problem.