Nest Thermostat Overreading

[MJN]

I've got a Nest 3rd Gen thermostat and have found it to be overreading by ~2C. Whilst I don't have any calibrated thermometers to check against I do have a variety (I didn't realise before now that I must have an unhealthy obsession with them!) which all agree to within 0.5C of each other so it really is suggesting the Nest is the odd one out. All measurements taken on a table top with no nearby heat/cool sources, being held in the hands etc.

Interestingly, restarting the Nest (by pressing-and-holding the screen for 10s) does appear to return the current temperature back to accurate but within a minute it has risen back to a ~2C overread. I thought it might be an internal heating issue (I tried disabling wifi to no avail as I know the Nest isn't compatible with all routers) but then it seems to drop the 2C on reset rather more quickly than I'd expect if that is the case.

Has anyone else witnessed similar and, even better, have any idea how it might be resolved?

 

[MJN]

To follow up on this post; I got in touch with Nest support and we spent a fair amount time going through diagnostics such as checking there aren't nearby heat sources or being in direct sunlight, questioning the accuracy of my thermometers etc - all what you'd expect and all fair enough. Their conclusion was that a difference of 2C is not necessarily unexpected as 'all thermostats calculate the temperature differently'. I wasn't quite sure what was meant by that, I think maybe the wording had been dumbed down for me but lost something in the process. I questioned this and after them going away to discuss it with someone else they came back and offered to replace the thermostat (and base) which I thought was generous, not least given it was outside the warranty period.

Since first posting I have discovered it is seemingly quite common but unfortunately with no obvious/common fix. Some have suggested it possibly being a software issue as they think they only started seeing the problem after the last update in early 2020. Finger's crossed the new unit won't have the same issue.

 

[ianmcd]

I wish you were closer , I would love you as a customer