I was looking into the EQ3 max stuff as well. This looks like what you need.
https://www.box.co.uk/EQ-3-Max!-Boil...html#DetailTop
It seems to be missing on a lot of other sites selling the TRVs, gateways, etc though which seems strange and if you search the box website for EQ-3, it doesn't appear! Would be good to know if this works. I don't see why not though. Hopefully save you swapping everything out as I like the look of the system.
My friend has the Honeywell EVO stuff fitted and it's very good although I find the valve heads a bit bulky (but then again, it's next to an ugly radiator so.....)