I also have Nest Gen 3, it was claimed that Mihome Enegenie TRV heads should have worked with Nest, and the heads did pair with Nest, and using the MiHome app to alter Nest temperature and the TRV followed the change, however turning the dial on Nest or scheduled changes did not cause the MiHome head to follow, so had to remove the pairing and simply use the same schedule for both Nest and MiHome.
It really was wrong way around, want the TRV to tell Nest not the other way around. MiHome Energenie does use IFTTT so one can use geofencing with them, and maybe you could link to Nest using IFTTT I have not tried. However when using the Energenie heads in last house which was still on/off control with the thermostat but a modulating boiler, (this house is oil so not modulating,) I found the anti hysteresis software was OTT, Drayton Wiser claims to have smart TRV heads that like Nest predict what will be required, however the Energenie heads set 16°C overnight although never got that low, and at 7 am to 20°C it was nearly 11 am before actually showing 20°C current temperature, so I cheated, and set to 22°C at 7 am and 20°C at 8 am and then it was at 20°C by 8 am most mornings.
The OTT anti hysteresis means not much good for geofencing, but does not seem to be a problem, the Nest geofencing works well, and clearly the home can not heat up if boiler not running, so when I moved here I got an extra 5 programmable TRV heads, this time eQ-3 bluetooth version at £15 each from the internet, and if anything they seem to work better than the Energenie type. So I will try listing good and bad points.
- eQ-3 can be manually set, not need for an app. But will only work bluetooth with one phone.
- eQ-3 has open window function so turns off kitchen heating when unloading car.
- eQ-3 allows one to set your own eco and comfort temperatures, so one button flicks between them.
- eQ-3 has local display of target temperature.
- eQ-3 has over and under movement fault codes.
- Energenie also show current temperature.
- Energenie can be controlled by many devices, PC, tablet, and phones.
- Energenie is wifi enabled and can use IFTTT weather production and geofencing etc.
- Energenie has two sensors and compensates for radiator water temperature.
In all I would actually say eQ-3 are better, I have actually stopped the temperature drop over night on the TRV head, this seems to work better as wide open when Nest starts the boiler, but will admit the display of both current and target temperatures with the Energenie did make setting up easier.
If current over target close lock shield a tad, and if current under target open a tad, once set it was spot on with modulating boiler, not quite as good with mark/space boiler control. I set lock shield using energenie then swapped for eQ-3.
If I was starting over I would not go for Nest with non modulating boiler, and I would use all eQ-3 thermostats. I find walking into a room and pressing eco/comfort button far better than having to get mobile phone to change temperature, energenie does have comfort/eco setting but the temperature is fixed, not user defined like eQ-3.
So from the research I have done, Drayton Wiser electronic TRV heads seem the best, however I have found having a head which shows °C rather than silly *123456 is the big thing, it would be nice to see the controls each app offers
shown is Energenie, which I would not recommend, the eQ-3 app is multi pages, example here
it is easier to set up using app than manual, and with bluetooth where two radiators are in same room they can be linked, but once initial set up done hardly use bluetooth, I tend not to walk around house with phone glued to ear.
