[werk_ag]

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Thanks for your detailed reply and in advance for your work on the code to solve the issue.

Zak, it isn't an issue on the code, as it is working for a large number of users, including me The issue (which isn't also an issue) is with the Thingspeak servers, which due to load, in some countries they can't answer as fast as before. One of the suggestions of the guys from Thingspeak team is just add a delay to wait for server response. As said, instead of adding delay, I preferred to modify WeatherDuino code to use their own lib.

Regarding the CO2 sensor, when doing a zero point calibration manually (your model doesn't allow doing it remotely), be sure that the sensor is at fresh air for at least 20 minutes, and when putting HD pin to GND for 10 seconds, make sure your breath doesn't reach the sensor, this is very important.

Also check if your MHZ-19 is model A or model B. B is newer and best.