The surprising thing is that when placed in the same location as the previous one and both operating simultaneously, the CO2 level readings are very different. For CO2 levels close to 490 ppm, the new device measures approximately 90 ppm (+12%) more than the previous one. This difference increases when CO2 levels exceed 1500 ppm, reaching almost 300 ppm more than the previous one.
I’ve conducted various tests, and the differences persist. I even changed the USB power adapter. I also swapped their positions, despite them being very close.
The temperature and humidity readings are also different, but since the accuracy can be adjusted in the settings, it’s not a problem.
In the case of CO2, there’s no calibration adjustment, and I believe that, given the results, this calibration adjustment is absolutely necessary. The test discredits the readings and the system’s operation, and it should be improved.
The sensor in your old device may be dirty. Clean all openings in the device with a vacuum cleaner. After cleaning, the reading should be more similar to that of a new device.
On the other hand, you’ll never get similar results because the device’s accuracy is +/- (50 ppm + 5%). So the difference between one device and another can be as much as 100 ppm. In your photo, the difference is only 62 ppm, so that’s not bad. (551 - 489 = 62)
This is not a 5% value.
The accuracy of this device is +/- (50ppm + 5%). This is a deviation from the reference value.
If you assume the reference value is 510ppm (+/- 50ppm), then each device is within the error tolerance.
In fact, after cleaning all the openings of the old device with a vacuum cleaner, the reading of the old device is now almost identical to the reading of the new device.
The time difference between the two devices is approximately 4 MOTHS. (See screenshot)
