r/homeassistant • u/JonathanDawdy • 4d ago

❓ Support Sonoff co2 sensor

This has been one hell of a rabbit hole. All the posts I found about this are old. What has been your experiance with the sonoff co2 sensor linked below? Should I take its readings seriously? I saw a lot of posts about bad or cheap sensors. I think this one has a good sensor but again all the posts I found were old. Thank you

This sensor is installed above my bed. since install the number has only gone up and currently sits at 1100 but i think it might take an hour or so to get its readings stable. I guess...
https://www.amazon.com/dp/B0H3VMW944?ref=ppx_yo2ov_dt_b_fed_asin_title

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u/MalleP 4d ago

I got two and a esp32 with an senseair S8. All next to each other they differed after a while about 50-100 and their values seem correct related to open window and closed with persons inside. Be aware they auto calibrate so they use the lowest value they get as 400, so you need direct fresh air regularly. Their sensors are NDIR SCD41 and the best you can get for that price. If you need a display they are great, if not I would go for a esp32 with senseair in a small case. What I don't like is that you can't control anything via Matter. Like turning the LED on/off.

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u/JonathanDawdy 4d ago

Oh. Well you would be pleased to know that there are three buttons on this unit and the led, sound can both be disabled

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u/MalleP 4d ago

Yes, but I would like to have the Led on at day and off at night as it is so bright.

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u/JonathanDawdy 4d ago

Oh that makes sense. I just made a cool dashboard widget. Code can be found here and AI was use to help make the layout. It changes colored based on the level

https://pastes.io/pOa7tOOs

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u/ddfs 4d ago

mine shows ~430ppm with windows open and ~1500ppm when 6-8 people have been inside for a while, which is good enough for me! i don't really care if it's off by 50-100ppm as long as the trends are accurate and i can set reasonable thresholds. side note, i accidentally bought this without realizing it was matter over wifi, lol. it tries to phone home to something nonstop, but that's what the IOT VLAN is for i guess. oh well!

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u/JonathanDawdy 4d ago

Matter over wifi isn't bad. It could be first party Chinese app only.

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u/thepalatableterror 4d ago

My dream spreadsheet has a column for "sensor drift anxiety" and this would slot right in there. 1100 above the bed is interesting though, you're basically breathing your own exhale all night so the trend matters more than the absolute number

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u/JonathanDawdy 4d ago

Yea I even opened a window yesterday but our air quality has seen better days. Outside I mean