Are you sure you have a CO2 monitor and not an eCO2 monitor?
A lot of cheaper CO2 sensors really detect VOCs and try to estimate CO2 from that.
A lot of cheaper CO2 sensors really detect VOCs and try to estimate CO2 from that.
It ain't cheap.
NDIR Sensor (Non-Dispersive Infra-Red): Measurement range 400–5000 ppm Optimum Accuracy ±50ppm ±3% within 10 – 35°C / 50 - 95°F and 0 – 80%RH after initial calibration time
Can you tell from that description whether it's a true CO2 sensor?
I am less surprised than other people that making an open fire indoors increases CO2 levels. Where do the combustion byproducts go if not into the air.