I have had an indoor monitor for 6 months now. Yesterday I assembled a second. After setting up the second one, it is showing much double the C02 and TVOC readings and lower PM2.5. It is also showing temperature in F, which I like. Is there an update or calibration I should be doing to one or the other, or something else that might cause this? I am worried that my older monitor is showing low levels, and has been for months.
CO2 could be off due to needing calibration, either the old or the new one.
I would start by setting the new device outside or near an open window for 5 minutes and then request a CO2 calibration from the dashboard. This will reset the current values to 400. Then after another few minutes after you see the number get near 400, move it back to where you existing device is and check after another 5 minutes and see how they compare.
VOC is an index based on how the air quality has changed over the last 24 hours be default, so a device that has recently rebooted will have different values than one that has been online for a longer time.