I had an install of the 3rd gen Nest last week, happy with it so far and the installer dude was a pleasure to deal with.
However one point I'm not clear on - installer indicated that although my boiler has separate zones for Hot Water and Radiator control, he was unable to wire the Nest to control the HW zone because that would require a Registered Gas Installer to open the boiler.
Can you confirm if this is the case - i.e. are Electric Ireland requiring customers to hire a separate RGI to complete the Nest install, at customer's own expense, despite the fact that both my electicity and gas are supplied by EI? Somewhat surprising, since I would assume that EI employs many RGIs?