Thank you for the link, I am having problems at the moment with my central heating, it may well be due to interference from power line technology, where the problem lies is some one like me complains then Ofcom arrives, and some poor unsuspecting neighbour is told don't use those any more, we are taking them for safe disposal, and then all sorts of things fail due to no internet connection. Which could very well be their central heating.
I know my son put a LAN socket at every radiator ready to fit eTRV's at latter date, but then found you simply can't buy hard wired eTRV's it's wireless or nothing. It seems mine use the 70 cm band, which is shared so some one can be transmitting at 25W which will likely knock out the milliwatt used by eTRV's.
As to why they are not simple WiFi and need a hub to connect to, and don't connect direct to router I don't know. The problem is what is sent is secret, clearly the hub programmes the eTRV but how much is sent day to day and how much is stored in the eTRV I don't know. Cheap ones store it all local you don't have any coms, you set it on the valve head it's self.
There is a odd situation in the UK, I can sell radio equipment to anyone, so can any shop, unlike a gun where the buyer has to have a licence to buy, anyone can buy radio equipment, in Hong Kong before the take over I had to show my radio licence to buy a radio, but not in the UK, it is the person using it who is committing an offence not the person supplying it. CB was a real problem, shops could sell items which they knew the buyer could not legally use.
If I could work with all wired internet I would, however to day we don't have the option, I can't if I want to connect my mobile phone to the internet without WiFi, it has no LAN port. So we all have to think twice about any wireless device, if I buy some bluetooth head phones at £5 and then they get banned I am not that worried, if however I have spent £300 plus on central heating controls I am worried if they don't work or are banned.