Looking at the
instructions is seems the boiler has it's own anti hysteresis software which is matched to the thermostat, so you will need to read carefully to see if Hive is going to work, it does seem it uses extra low voltage control so duel channel Hive will not work.
The whole idea of the modern "Smart" thermostat is to work out at what point to turn down (ebus type) or switch off (on/off type like Hive) to allow for the heat retained in the radiators so it does not over shoot and cause a hysteresis curve where the temperature is in a sine wave as it over and under shoots the selected temperature.
The modern gas boiler is designed to modulate, that is turn down to output, rather than simply switch off/on, and is designed to work with thermostatic radiator valves (TRV) so either the return water temperature or connection to ebus matches boiler output to demand, this will reduce the hysteresis to a very low valve. However there is a problem using water temperature in that unless boiler is running it can't sense if required, so without some thing extra it will cycle all summer, so we want some thing to turn it off when weather is good.
So the wall thermostat is used to switch off boiler in warm weather, but if set to turn off boiler in cool or cold weather it can upset the boilers own control using return water, so boiler does not modulate as it should and so uses more fuel than it should.
Hive have a system not seen used with any other wall thermostat, it uses "heat on demand" so the temperature set on the wall thermostat does not really matter as long as lower than temperature required, as the Hive TRV heads tell the wall thermostat to switch on boiler if not satisfied, so the Hive TRV heads keep the boiler fired up when required.
However this clearly only works if you have replaced as least some TRV heads with the Hive programmable ones.
As with every system it sounds great, but not a clue if Hive actually works, I have Nest, not quite the same system, well the reverse the Nest wall thermostat should tell the TRV what setting to use with a follow command, which I found does not work, I have to set the TRV manually at the same schedule as wall thermostat, however not seen anyone else complaining, so either I am unlucky, or others are not using Energenie TRV heads with Nest but hope it will work without, and since Nest will connect to boiler ebus with gas boilers likely it does, but I am using oil so boiler does not modulate.
If some one asked me to fit a modern control I would go for EvoHome as it's been out a long time and it is known to work, Tado may work, but they will not release info, Hive may work but the TRV head was only added in 2019 to make the system comply with new rules, and Nest may bring out their own TRV heads soon rather than use Energenie, but I can't be sure the others work, but EvoHome has been out for a long time, OK if using OpenTherm it needs an add on module when built into Nest.
I would love to see some one report on fitting Hive TRV heads as to if they actually do what it says on the packet, seen report of problems getting them to pair with the wall thermostat, but this could be that wall thermostat was too old to work with the new TRV heads. If you do fit it, please tell us all how it goes.
My Nest system (on oil boiler not modulating) does work well, however I have wasted money on the Energenie TRV heads, the much cheaper eQ-3 bluetooth programmable heads work just as well and much cheaper at £15 each rather than £45 each, and that's the rub, do you use cheap programmable heads or expensive ones the latter which ties you to one make of wall thermostat? I have 4 Energenie and 5 eQ-3 and to be frank the eQ-3 work better for me, pressing one button to swap eco to comfort works well for me, I don't need the geofencing which the Energenie does have.