Thanks to those who posed here (DandM Dame and mas.sheraton) I have managed to get my Nest 3rd Gen working.
My problem:- failure to establish connection between heatlink and thermostat (H72 error). This persisted despite many reboots, units being next to each other etc.
Solution : Use the wired setup, connecting T1 and T2 of heatlink and thermostat) and completed the setup steps without a wireless connection. This allowed access to main menu and the factory reset option. Started working immediately for me after this, would recommend you also do a heatlink reset (hold button for 15 sec) just before factory reset on the thermostat.
Thanks @oldturkey03 great guidance, I've done as you recommended. All the best - Jim.
Jim Craig さんによる
@jimcraiguk Awesome! Great job, thanks.
I was on technical support for half an hour with the Heat link unable to pair with the Thermostat (gen3), went through all the usual hoops, but the only solution was (after upgrading the software with software upgrade function of the thermostat) was a complete reset of both and NOT connecting to the WiFi and NOT setting up the app. Just skip those steps and it'll able to pair with the Heat link. You can connect to the WiFi and app after that.
I had same issue w/ new Nest 3 + Heatlink. Tried everything and all I got was "blue pulse" on heatlink and h71error on thermostat after many minutes trying to connect wirelessly. Finally got with knowledgeable Nest tech. What worked for us was to connect the thermostat with the T1, T2 wires directly to heating unit. This allowed the thermostat to fully "install" w/o wireless connection. Once installed, I selected and performed a factory reset of the thermostat. On the reset reboot, the thermostat connected BOTH with wires and wirelessly! Then just disconnect the T1, T2 wires and all is well for me. Only trying to connect wirelessly prevent the thermostat from fully setting itself up and was not able to select a full factory reset which then resolved my issue. Frustrating? yes, and instructions should suggest to try a wireless connection first if all else fails. (I brought the thermostat close to the heatlink to use about a 3' piece of T1/T2 wire; and micro usb to power the thermostat). Good luck.
DandM Dame さんによる
Had the same problem the only solution is what DandM Dame suggested. Pretty easy. Isoloate the power to the boiler and Heatlink device. Take off cover and connect two cables on T1 and T2 Terminals. Then connect to the nest themostate. Then do a factory reset, I also had to re-enter the pairing code from the Heatlink. Really what a faff.