I have seen numerous posts about the exact same issue stretching back for several years, but unfortunately each thread seems to die a death either because of a lack of replies/considered replies or I am guessing the user found the solution themselves and didn't post an update.
Today I made the mistake of contacting Google support via live chat, and after what seems a lifetime of apologies about how it is so cold where I am and how sorry the agent is and "let's work through this together", after restarting the Nest their best solution was "Let's give it 24 hours now to see what happens". Despite knowing already that it's way past 24 hours since the first restart and reset etc.
Anyway, onto the problem:
Nest v3 on a gas system boiler controlling central heating and water heating. All has worked fine, however it's been apparent for a few weeks that water wasn't heating to schedule on random occasions and when I looked into it, the app was showing water heating was ON, and I could hear the valve opening etc. but the boiler wasn't firing.
I tried some troubleshooting from Google (reset the schedule, only program it from the controller and not the app etc. to no avail).
As of a couple of days ago there is not heating of the hot water at all. The app shows it is ON according to the schedule and the valve activates, but the boiler isn't triggered. First thought was tank thermostat although I believe if that we faulty then the valve wouldn't open.
Manually activating heating at the Nest box sets the water heating and central heating into life, the thermostat will happily cut the water heating off etc. so appears to be fine.
So it doesn't appear to be the boiler, doesn't appear to be the thermostat so I think it is either a software glitch (no updates available) or a hardware glitch in the Nest box.
However, when I turn the heating on or off via the app or controller I still get a click in the box as if it works to that point.
So, does anyone know is the boiler fires from a different connection/pin from the Nest box on manual override to when it is fired on a schedule/boost, as if it is that would probably be the best place for me to look next to see what is being output Volts/Amps through that pin?
Thank you
