Carbon dioxide (CO2) detectors
April 25, 2022 1:36 PM Subscribe
Are expensive CO2 detectors really that much better for casual home users than the cheap "effective CO2" detectors?
The "good" CO2 monitors use NDIR sensors, and cost a lot (like the Aranet4). Cheap units track "effective CO2" levels by using inexpensive sensors that measure VOCs -- and are regarded as less reliable, because of the assumptions underlying the math they perform on those measurements.
I believe that I only need a sensor capable of measuring up to 10,000 parts per million for home air.
Is an eCO2 monitor good enough for keeping an eye on the air in my home office? Or should I save up for a good one? Or make one out of a Raspberry Pi and a bare sensor?
The "good" CO2 monitors use NDIR sensors, and cost a lot (like the Aranet4). Cheap units track "effective CO2" levels by using inexpensive sensors that measure VOCs -- and are regarded as less reliable, because of the assumptions underlying the math they perform on those measurements.
I believe that I only need a sensor capable of measuring up to 10,000 parts per million for home air.
Is an eCO2 monitor good enough for keeping an eye on the air in my home office? Or should I save up for a good one? Or make one out of a Raspberry Pi and a bare sensor?
If you have air purifiers with carbon filters that are designed to remove VOCs, I'm guessing that will absolutely ruin the "effective CO2" measurements.
posted by meowzilla at 2:51 PM on April 25, 2022 [1 favorite]
posted by meowzilla at 2:51 PM on April 25, 2022 [1 favorite]
The cheapest NDIR CO₂ monitor I can see on Amazon UK at the moment is £18.99, and that's probably not brilliantly calibrated, but it's also not going to be anything like as affected by VOCs and particulates as the pre-2020 consumer “CO₂” meters were*. So in my opinion, there's no value at all to using one of the sensors that uses thermal mass as a proxy, or however they work.
*disclaimer: I'm bitter because in January 2020 I needed to show a flue was venting into my house (using an outside air source, so no carbon monoxide risk), and there was nothing affordable to prove this point.
posted by ambrosen at 3:13 PM on April 25, 2022 [1 favorite]
*disclaimer: I'm bitter because in January 2020 I needed to show a flue was venting into my house (using an outside air source, so no carbon monoxide risk), and there was nothing affordable to prove this point.
posted by ambrosen at 3:13 PM on April 25, 2022 [1 favorite]
Why do you want to measure CO2?
My understanding is that it is not really possible to know that you're getting a accurate CO2 reading for significantly than ~$100 USD (you may happen to get a sensor that is correctly calibrated, but if you do, it'll be luck, not something you can count on without verifying it against a more expensive meter anyways).
If you do want to go the bare sensor route, I've heard the SCD30 recommended, which runs around $60 for a single sensor right now. So, you might save a bit of money, but if you have the experience to set it up, it might be hard to justify the time and effort as something other than just having fun — I don't think it'd save you too much money over buying a premade device that uses that sensor, all said and done.
posted by wesleyac at 9:59 PM on April 25, 2022 [2 favorites]
My understanding is that it is not really possible to know that you're getting a accurate CO2 reading for significantly than ~$100 USD (you may happen to get a sensor that is correctly calibrated, but if you do, it'll be luck, not something you can count on without verifying it against a more expensive meter anyways).
If you do want to go the bare sensor route, I've heard the SCD30 recommended, which runs around $60 for a single sensor right now. So, you might save a bit of money, but if you have the experience to set it up, it might be hard to justify the time and effort as something other than just having fun — I don't think it'd save you too much money over buying a premade device that uses that sensor, all said and done.
posted by wesleyac at 9:59 PM on April 25, 2022 [2 favorites]
On a whim I bought the CO2Meter RAD-0301 monitor a few years ago... in my memory it was $25 so I assumed it was of the cheap variety you mentioned, but looking again now it appears I paid $75.. and according to the description, it is using NDIR sensors?
It's actually been pretty useful... living in a small NYC apartment, I've definitely had it start beeping a warning when I've had 4 or more people in the apartment for a while, or even when using the oven/cooking a bunch. A good reminder to open a window!
posted by Grither at 4:42 AM on April 26, 2022 [1 favorite]
It's actually been pretty useful... living in a small NYC apartment, I've definitely had it start beeping a warning when I've had 4 or more people in the apartment for a while, or even when using the oven/cooking a bunch. A good reminder to open a window!
posted by Grither at 4:42 AM on April 26, 2022 [1 favorite]
We use a Nest Protect and like it. Especially the nightlight feature when we get up to pee in the middle of the night.
posted by Hey, Zeus! at 9:46 AM on April 26, 2022
posted by Hey, Zeus! at 9:46 AM on April 26, 2022
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If you only “want” to monitor CO2 then a cheap unit will likely suffice for tracking day-to-day levels without absolute accuracy.
Reasoning: I faced a similar question when seeking to monitor aldehydes, and decided that in that case I ought to step up to a high grade unit or else use a cheaper monitor in conjunction with a specialist filter mask, because aldehydes often end up being a “need to monitor” rather than a “want to monitor”.
Full disclosure, I ended up with quality monitor AND a filter mask, so my decision-making could be suspect.
YMMV, but want-vs-need was my metric.
posted by aramaic at 1:55 PM on April 25, 2022 [1 favorite]