Hi guys, sorry for the late reply, I’ve been travelling for most of September,

Please use only the server values, visible on the dashboard or returned by the server API, as those are further compensated to correct issues related to internal heating that affects temperature and humidity readings.

Although all units are calibrated against a common reference, there is a software interface in place that can be used to do additional adjustments where needed. We can apply this to any discrepancies in the returned parameters when compared to other equipment.

Country for E7 and E2 is set to AU.

For the 820000FA, please do a new test for Temperature and Humidity and let me know if you need any offset to be added. Again, make sure you are using the server returned results, not the local json. From you last post the correction would be T:-3.8 and H:+8.83
The CO2 sensor has an autocalibration algorithm, that triggers every 24h. Most likely the readings will be correct.

The VOC AQI algorithm has the purpose of providing comparable readings between the various MOX sensors used in the A3 units. It is very similar to the one developed by Bosch for their BME680 sensor. It uses the last 24hours of VOC raw readings to establish a minimum and a maximum, and then the readings are computed as a percentage scaled on the 0 to 500 interval. If you saw a big change it was due to a new 24hours interval introducing new min / max values to the calculations.