Ok, got this working......
You need one of these:
https://www.amazon.co.uk/Technologies-RC840T-240-Switching-Electric-Transformer/dp/B0037MXM1C?th=1
Wired like this:
R, W & C to the EcoBee are fairly self explanantory (Ignore the PEK wire, not required):
On the boiler side, in my case a...
I know this is an old post, but I'm trying to do exactly the same thing, and my electrician has given up trying to get this arrangement to work, so looking for some help. I ended up buying an Aube Technologies RC840T to facilitate this, but reading wcavanagh's comment suggests it should be...