Netatmo thermostat to Potterton boiler

[Luke watson]

Hi, I am hoping to replace an old thermostat with a Netatmo one, by attaching the four wires from the Netatmo into the Potterton boiler Terminal Block following the Netatmo guide (also here:

). The boiler is a Potterton Promax Combi HE Plus.

It looks pretty straightforward except that the existing wiring that I will be replacing includes an earth wire, where the Netatmo doesn't (only black/grey control wires and brown/blue live and neutral wires).



Do I need to connect an earth wire somehow or is the boiler already earthed before reaching the terminal block?

Many thanks.

 

[cross thread]

The boiler must have a earth, netatmo won’t

 

[Stuckinarut]

The Netatmo is likely double insulated, so the earth (circuit protective conductor) isn’t really required, but the earth is required from the fused connection unit to the boiler. What is the existing thermostat? It seems like it’s 2 or 3 wire, if yes, the Netatmo will require piggybacking anyway.

 

[RandomGrinch]

It looks pretty straightforward except that the existing wiring that I will be replacing includes an earth wire, where the Netatmo doesn't (only black/grey control wires and brown/blue live and neutral wires).

I may be wrong, but it sounds as if you are a little confused with the purpose of the existing cable.
The existing cable is a 5 core flex, this not only has a connection to the existing thermostat, but provides the power to the boiler.
Your Netatmo relay wiring loom would piggy back the existing blue and brown wires in the L and N terminals of your boiler.
The grey and black wires would go into terminals 1 and 2.
The grey and yellow wires currently in terminals 1 and 2, would be removed and safely isolated in a separate terminal block.
It may be possible to remove the wiring to the old stat, but we'd need some more info first.

 

[Luke watson]

Thank you, you're absolutely right - I hadn't realised the power came through that wiring too. I can easily add the Netatmo wires into the block, and presumably I then need to remove the old stat or disable it.

Here are a couple of photos, one showing the power and the stat, the second showing some earthing wiring.

 

[RandomGrinch]

and presumably I then need to remove the old stat or disable it.

You could do, but as it is only a receiver, and it's out of the way, there's no real need to do much about it, as long as you take...

The grey and yellow wires currently in terminals 1 and 2, would be removed and safely isolated in a separate terminal block.

If you want to explore further, it appears that the flex is daisy chained from the FCU and through the BG receiver; having a look at the wiring behind there (with power safely isolated) may show us what's going on.

 

[Luke watson]

Thank you so much. I have wired up as you said (see below) and it all seems to be working. Can you confirm this is what you meant about isolating in a separate terminal block, and would you consider this safely done? They wouldn't fit in the area labelled terminal block, so the two wires are sticking out of there as you can see in the last photo.

Big thanks.

 

[RandomGrinch]

Thank you so much. I have wired up as you said (see below) and it all seems to be working

Well done, that's a good job

Can you confirm this is what you meant about isolating in a separate terminal block, and would you consider this safely done?

Yes, that's perfect.
These wires shouldn't be carrying any voltage; we just want to ensure they are left in a way that it's improbable for them to touch any other wires, or components.

 

[Luke watson]

Amazing, thank you so much for all your help (and others) - hugely appreciated.