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9. Sensor Calibration
CO2:There is an easy way to find the CO2 sensor is
drifted or not: put the sensor in outdoor open air locations,
away from any combustion exhausts, wait for 30 minutes,
you should see the CO2 reading is /-10. If it is
far from this reading, you can wait for some more time,
and test it during night to confirm. Once it is confirmed,
you can open the back housing, and use a clipper pin to
press the Calibrate button as below figure shows, leave it
for 30s, and the reading will be shifted back to 420ppm.
Figure 3
