Solution to an easy Away mode using an existing Nest
I currently use a Nest on our combi boiler and it works just great but have started to use Tado Smart TRVs to control the temp in each room/zone. Obviously at the moment there is no call for heat by individual TRVs as I don't have a Tado Smart Thermostat installed yet. Having read thru numerous threads it appears that changing to an Away mode with Tado (and I don't want to use Geofencing BTW) is very difficult and not at all flexible, so I have come up with a work around that I think will work and will also save me throwing my Nest away when I install the Tado Smart Thermostat.
What I plan to do it put the Tado Smart thermostat on the Nest's call for heat return to the boiler (see red dot on image). I would then leave the Nest on an unreasonably high temperature permanently, which should then mean the Tado can control the call for heat if required.
When I'm away I can simply turn down the Nest to our usual Away temperature which effectively isolates any instruction by the TRVs as the Tado would not be able to send a call for heat to the boiler because terminal 3 would be left open.
Anyone see any holes in this ?