The wiring diagram shown on case does not seem to match the thermostat, so I would actually test thermostat to see what it does, but the other problem is the programmer only shows one wire in L (Line) the two relays are volt free, Hive is not volt free when using the CH and DHW version, so it may not be suitable?
In the main boilers have three methods of controlling them.
1) 230 VAC i.e. mains voltage.
2) 24 volt may be either AC or DC.
3) Variable voltage the boiler does not switch off/on but up down.
Clearly your not using third option, even if the boiler can use it, and Hive can't use the third option either, so if you want Hive even if the boiler allows control with the ebus, you can't use it. With a single channel Hive it does have volt free contacts, but when it controls domestic hot water as well it does not, you must check on boiler spec.
There are loads of wall thermostats/hubs which like Hive connect to internet and like Hive link to the TRV heads. Some like Hive you can add TRV heads latter, some use the head to control the boiler, also some have other controls my son tells me Nest can link to the smoke alarm and detect people at home and turn up heating when people are at home, I have Nest but not found that function, many functions are IFTTT and I have not worked it all out.
So it may be your using Hive to match up with stuff you already have? I decided to fit Hive as I liked the way the TRV heads worked, but found I needed volt free so fitted Nest instead. Hind sight, and hind sight is easy, should have fitted EvoHome, but Nest does work well.
So what is your reason for fitting Hive, maybe there is a better option for you?
