A customer called us recently from inside their indoor greenhouse in Colorado. They had just installed an iSense CO2 controller hooked up to an alarm. Their question was very simple:
"How do I know if the CO2 alarm is working?"
Fortunately, the answer is simple: take a deep breath, hold it for a moment, then blow it directly into the meter's air vents. Repeat this several times.
Exhaled breath is approximately 4% (40,000ppm) carbon dioxide, which is enough to activate any CO2 safety alarm.