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Are you sure? I have a MH-Z19 and it drifted by more than 50% (baseline went to about 180-200 ppm) after a month or two without calibration. It is from a reliab
by alwayslikethis 4y ago
Are you sure? I have a MH-Z19 and it drifted by more than 50% (baseline went to about 180-200 ppm) after a month or two without calibration. It is from a reliable vendor and the readings are quite stable, so it's unlikely to be a fake sensor.
- wkat4242 4y agoWell I heard this from someone using Sensirion SCD30/31s in implementations for industrial purposes. In my own application I use them at home only and I often have a chance to air them. What you need to do though is specifically turn off the auto calibration. Because if you don't, it will view any near-400 readings as '400' (e.g. thinking it's outside air) and the calibration is dragging itself off over time. The MH-Z19 is a bit cheaper and I don't really have direct experience with them, though I do have one in my Awair Lite.
- ysleepy 4y agoI have a MH-Z19C and have been running it with auto-calibration disabled for over a year and it didn't drift much. Is is possible that you have auto-cal on and the sensor is never exposed to true outside air? It uses some sort of minimum tracking to calibrate the ~400ppm point. This is anecdata though.
- wkat4242 4y agoExactly I'm pretty sure this is what it is. It won't drift much but you do have to turn the auto calibration off, otherwise it will grab any low CO2 moment and try to calibrate to it, drifting further off track with every calibration.