Nest Gen 3 Installation with Baxi Combi MaxFlow WM Boiler

[Martin Cobb]

I was hoping to install the Nest Gen 3 on my Baxi Combi MaxFlow WM Bolier.

So far I have found the following guide on this forum for a similar boiler (i.e. it has the same wiring requirements from what I can tell) https://www.diynot.com/diy/threads/nest-thermostat-and-baxi-combi-105e.416527/ . The only reason I have raised a new query is that this related to a Gen 2 Nest, and the installation booklet seems to give different wiring diagrams to what is now included in the Gen 3.

I have mocked up the wiring diagram using the previous forum thread as below (I understand I may even be better wiring the N and L to the supply side, so before the 2a fuse?)

The Nest Gen 3 installation doesn't show this configuration

Would I go with the low voltage option per the Gen 3 instructions, or would something similar to what I have mocked up work better?

I have included a link to the installation manual of the boiler below, in case that is of assistance.
http://interpart.partsarena.eu/System/DATA/Dx/DS1/installation/S074/I51-S074/I51-S074.htm

Thank you for taking the time to read my query!

 

[cross thread]

all the baxi combi boilers i have wired are 240v switching ,but never wired your model

 

[cross thread]

section 8.7 240v switching

 

[Martin Cobb]

section 8.7 240v switching

Would how I plan to wire it cover 230v switching? The manual shows an identical terminal block to that of the Baxi Combi 105e, with a Live, Neutral, Earth, "1" and "2". The "1" and "2" wires being for a thermostat, hence why I believe they should go to the heat link, and then the heatlink would also need power, hence the L and N wires.

 

[stem]

There are several ways to connect it. The connections shown in the diagram you posted is just fine. The N & L would be better on the incoming supply side and don't forget the earth connection.

 

[Dave Wilson]

I have just purchased the nest gen 3 I am happy that 1 and 2 on the baxi 105e boiler connect to 2 and 3 on the heat link.

However the neutral and live are confusing me, do they connect from the rh side of the terminal block , brown and blue wires? If so do the brown and blue wires stay in the terminal as well and the L and N for the heat link? Or do they need to be removed?

 

[stem]

Generally it's better to connect the wires to the incoming side of the terminals ie those labelled 'Live (brown)' and 'Neutral (blue)' shown on the left. All of the existing wires in these terminals need to be left in place.

 

[Dave Wilson]

Thanks, so the existing wires coming into the terminal (3 amp supply) and the L and N for the nest will both be in the same corrosponding holes? As in live and neutral coming in from the 3 amp supply and going out to the nest live and Neutral in the same side and same holes?

 

[stem]

Yep

 

[Dave Wilson]

Finally is 2 core flex fine for both connections to L and N and 1 and 2?

 

[stem]

Yes, although personally I find it easier to wire the Nest Heatlink in solid core. The terminals are quite small and close together so if you do use flex, watch out for any stray whiskers poking out that might cause a short circuit.

There is an earth connection on the Heatlink, but according to the instructions its only required if you are using T1 & T2 to power the thermostat, instead of using a separate power supply.