When I received my Atmotube Pro 2, the CO2 readings were in the “Good” range (400-800ppm) for a number of weeks. During this time it had always been in the house. Then in mid-December I took it for the first time on a 1 hr walk outside. Here in Minnesota, the temperature was in the low teens (Fahrenheit). During the walk, all the readings were as expected, with the CO2 readings like the ones in the house. When I got back from the walk, I did some reading, etc at a desk near our air humidifier. Within a few minutes, the CO2 readings had gone up to over 1400 ppm. I connected this spike to the humidifier (maybe I shouldn’t have). That day I moved the Atmotube back into my bedroom where it had been, and my inside the house CO2 readings remained in the 1000-2000 ppm. For one day I left the Pro 2 outside (I was a little reluctant to do this because of the cold) and the CO2 readings were back in the 400-500 ppm range. The hope was that during the day outside it would recalibrate. When I brought it back in, nothing changed; the CO2 reading went back to 1000-2000 ppm. These in the house readings made little sense. So I ordered a second CO2 sensor - SwitchBot Meter Pro CO2 monitor (I got this because of the excellent reviews and they claimed their NDIR sensor was excellent). The SwitchBot and the Atmotube have been next to each other for the last day, currently the Atmotube is reading 1622 ppm and the SwitchBot is reading 828 ppm. My feel that my assumption is true in that the Atmotube CO2 sensor is not working correctly. What is the best way to have the Atmotube calibrate itself?
Hi. Negative temperatures may affect the sensor calibration. The operation sensor range is 50 - 104 °F. The best way is to open the window for 15-20 minutes. This is enough to perform the calibration.
You can find more guidelines here Recommendations for CO2 Sensor Usage in Atmotube PRO 2 | ATMO Support Center
If you trust the reference sensor - you can calibrate the Atmotube sensor by setting the exact ppm value.
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