4 ms·

I've had a few CO2 meters, and learned not to trust any <$100 as they don't really work. I look for meters that use non-dispersive infrared diffusion sensors (N

I've had a few CO2 meters, and learned not to trust any <$100 as they don't really work. I look for meters that use non-dispersive infrared diffusion sensors (NDIRs), like the Aranet4. I've found the TIM10 desktop model from co2meter.com to be accurate (AFAICT), uses NDIRs, and only US$139. I also have other air quality meters. (I collect measuring devices.) I wish there was a do-it-all air meter.

johntash 4y ago
Do you know if the Aranet4 can be used over bluetooth/wifi without internet access? I've been looking at a bunch of devices and haven't seen aranet yet. Also, have you ever put all of your devices near each other to compare the variance between them all?
- bradknowles 4y ago
  AraNet4 does Bluetooth, yes. Mine is doing that right now. You can get wifi bridges as well, see https://devel.aranet.com/products/ https://devel.aranet.com/products/
  - secabeen 4y ago
    ESPHome on a ESP32 makes a nice Bluetooth2Ethernet Bridge. I've seen Aranet4's on eBay for under $150 pretty regularly, so I'd look there.
- ellisv 4y ago
  Yes the base model not supports Bluetooth
- xolox 4y ago
  I got my Aranet4 because it had very good reviews and allowed local read out of sensor data without any "cloud" involvement. I've been very happy with it, the readings are integrated into my Home Assistant setup so automations can respond to high CO2 (e.g. turn on a fan directed at a window, when temperatures are high enough to have a window open).
  - ryansouza 4y ago
    I wrote a bridge to get readings in to Homekit and prometheus as well. Useful to track multiple sensors and process historic data easier than the app https://github.com/ryansouza/aranet4-exporter-go https://github.com/ryansouza/aranet4-exporter-go
Buttons840 4y ago
I have a TIM10 that was once reporting negative CO2 levels one spring with the windows open. I'm not sure what I think about it. It's not a scam product by any means, it can definitely tell when someone is in the room or a window is opened or closed. I needed the space and unplugged it awhile ago and just don't worry about CO2 levels currently.
- unlikelymordant 4y ago
  My understanding is that some co2 sensors assume the minimum value seen over the last 30 days is 400ppm as a calibration. This could possibly explain a negative value if the sensor has been in higher co2 environment for some time, and is suddenly exposed to the outside.
  - Buttons840 4y ago
    You're right. The instructions say to place the sensor outside for a time to calibrate it, which I never did.
- lovemenot 4y ago
  Does it require callibration?
  - schmichael 4y ago
    Yes. All consumer CO2 detectors I’m aware of take periodic calibration.
    - bookofjoe 4y ago
      Not Aranet4
      - schmichael 4y ago
        Yes you do. Once a year: https://aranet.com/faq/ https://aranet.com/faq/ Their data sheet also advises calibration if used at “high elevation.”
hrez 4y ago
Sensirion SCD4x CO2 Gadget is $60

johntash 4y ago

Do you know if the Aranet4 can be used over bluetooth/wifi without internet access? I've been looking at a bunch of devices and haven't seen aranet yet. Also, have you ever put all of your devices near each other to compare the variance between them all?

bradknowles 4y ago
AraNet4 does Bluetooth, yes. Mine is doing that right now. You can get wifi bridges as well, see https://devel.aranet.com/products/ https://devel.aranet.com/products/
- secabeen 4y ago
  ESPHome on a ESP32 makes a nice Bluetooth2Ethernet Bridge. I've seen Aranet4's on eBay for under $150 pretty regularly, so I'd look there.
ellisv 4y ago
Yes the base model not supports Bluetooth
xolox 4y ago
I got my Aranet4 because it had very good reviews and allowed local read out of sensor data without any "cloud" involvement. I've been very happy with it, the readings are integrated into my Home Assistant setup so automations can respond to high CO2 (e.g. turn on a fan directed at a window, when temperatures are high enough to have a window open).
- ryansouza 4y ago
  I wrote a bridge to get readings in to Homekit and prometheus as well. Useful to track multiple sensors and process historic data easier than the app https://github.com/ryansouza/aranet4-exporter-go https://github.com/ryansouza/aranet4-exporter-go

Buttons840 4y ago

I have a TIM10 that was once reporting negative CO2 levels one spring with the windows open. I'm not sure what I think about it. It's not a scam product by any means, it can definitely tell when someone is in the room or a window is opened or closed. I needed the space and unplugged it awhile ago and just don't worry about CO2 levels currently.

unlikelymordant 4y ago
My understanding is that some co2 sensors assume the minimum value seen over the last 30 days is 400ppm as a calibration. This could possibly explain a negative value if the sensor has been in higher co2 environment for some time, and is suddenly exposed to the outside.
- Buttons840 4y ago
  You're right. The instructions say to place the sensor outside for a time to calibrate it, which I never did.
lovemenot 4y ago
Does it require callibration?
- schmichael 4y ago
  Yes. All consumer CO2 detectors I’m aware of take periodic calibration.
  - bookofjoe 4y ago
    Not Aranet4
    - schmichael 4y ago
      Yes you do. Once a year: https://aranet.com/faq/ https://aranet.com/faq/ Their data sheet also advises calibration if used at “high elevation.”

hrez 4y ago

Sensirion SCD4x CO2 Gadget is $60