Nest Thermostat Set to 16.5c but Heating coming on at 17c/18c?

[uptoyou]

Hi, usually Nest thermostat is set to around 19c, but with gas prices it is currently set to 16.5c
But what I have recent today is that the heating is coming on before it drops to 16.5
Anyone know why this may be happening?

 

[Mister Banks]

Nest has a mind of its own. Presumably Nest is detecting that the room temperature is falling and will soon go below 16.5c so it has started the boiler to prevent that happening.

 

[ianmcd]

As above Nest is a learning thermostat, it anticipates heat gain and loss an an attempt to maintain a constatn room temperature

 

[uptoyou]

Thanks both!