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Comment by accrual

3 days ago

I'ver heard the Aranet4 is quite good for this but haven't yet been able to justify buying one. I do try to open windows frequently, though.

I don't get why they're so expensive. You can buy the ndir co2 sensor on AliExpress for around $10. And yet they want $180 for that thing. And measuring humidity and barometric pressure is a component that costs $4 or $5 for you or I to buy.

  • They’re not using a $10 sensor. They’re being very careful which $40 sensor they use. And they’re calibrating the rest of the device to produce an accurate reading across its range.

  • Quality CO₂ sensors are pricey. I previously had two from AliExpress, but both were unreliable and eventually broke. I finally got an Aranet4, and it’s been flawless for over a year so far.