I was using an MHZ-19B to measure indoor CO2 for two years or something. As I needed a second sensor I planed to get a new one. After hearing that the Senseair S8 should perform better and less fakes one around I got one of those and to compare it a new MHZ-19(C).
Yesterday I build a simple ESP32 based test project with all three sensors connected at the same time.
This is the result:
That doesn’t make sense. Those spikes for the S8 and the little ones for the new MHZ-19 doesn’t make sense at all. I was just sleeping in the same room and the spike at 19:00, no one was at home at all.
The S8 and the new MHZ-19 always spike at the same time but the S8 much more and the MHZ-19 peaks at the end of the spike of the S8. While the old MHZ-19 has a smooth incline as expected.
What is going one? Two broken sensors but somehow synchronized? Something in the real world triggering this? There is nothing: No fan, no light. Maybe temperature, but this is floor heating it should be quite stable.
Some issue in the ESP32 with the UART communication or some issue in the sensor code of ESPHome? Why would that only effect two of the sensors?
I am at loss? Has anybody experienced something similar or any other idea?
(I am also not happy about how noisy the S8 is in general (you can see it between the spikes). That is even with a median filter with a window size of 7. Is that normal for an S8?)