Add Sensor for Thermostat Temperature Measurement

[ttravisswan]

Description

Would it be possible to add a sensor to report the temperature at the thermostat itself? At present, the default Nest integration's temperature sensor uses the active temperature sensor as the reported temperature value, which makes historical temperature charts look wonky when the reference sensor changes.

Device (optional)

Nest Learning Thermostat

Additional information

No response

[iMicknl]

Not sure, and I don't own a Nest Thermostat, so hard to test... Would need the contribution from someone with this device (and development knowledge0.

[MaJonker]

But is there really a temperature-sensor present in the current version? I can't seem to find it...

[ttravisswan]

I have a Starling Home Hub to integrate Nest devices with HomeKit using the Nest API, and it exposes a field on the Thermostat object called backplateTemperature, which is the temperature at the thermostat itself. API documentation is here: https://sidewinder.starlinghome.io/sdc/#thermostat

The Google Nest integration in HomeKit uses the currentTemperature field as the temperature value for the thermostat, which means if you have a temperature sensor active as the "reference" temperature for heating or cooling, the temperature value for the thermostat in Home Assistant will show the temperature of the sensor rather than the temperature at the thermostat itself.

I guess what I'm asking is if this integration can be updated to create additional temperature sensor objects or entities that show the "backplateTemperature" value of all thermostats in the home, which would allow the temperature at the thermostat's location to be tracked over time in Home Assistant. Right now, if you change the referenced temperature sensor, the temperature of the thermostat abruptly changes (see example below - temperature jumps from about 70.5 degrees F to 72.5 degrees F after changing temperature sensors in the Nest app):