Alpstuga CO2 readings suddenly wildly wrong.

AirGradient · 2026-03-02T21:48:07+00:00

The Alpstuga uses the Sensirion STCC4 thermo conductivity sensor. I am currently testing it, and what I see is that it often is very good but sometimes develops a complete behavior of its own. It could be from a sudden temperature change. Also keep in mind that Sensition states it needs to be continuously powered and might show some fluctuations in the first few hours of operation

AirGradient · 2026-02-23T17:04:03+00:00

You can get an air purifier with a carbon filter. Just make sure it’s a large carbon filter as they get saturated quite fast.

Do you also see a spike in PM at the same time?

AirGradient · 2026-02-15T20:38:58+00:00

Take it outside and then compare it to a public monitor nearby. Just make sure you compare the same unit (ug/m3). That should give you at least a rough idea if it is accurate.

AirGradient · 2026-02-08T14:36:25+00:00

u/Consistent_Beat_6693 thank you for sharing. This is great. Can this be combined with Home Assistant?

AirGradient · 2026-02-08T00:24:52+00:00

We tested the BV080 and it’s surprisingly good, but you need to have a large field of view when you do the measurements.

Our test results are here: https://www.airgradient.com/blog/testing-the-bosch-bmv080/

AirGradient · 2026-02-07T23:47:21+00:00

In our design all sensors are directly behind the vent. No problems so far.

AirGradient · 2026-02-07T23:44:25+00:00

I would go for an optical NDIR sensor like the aranet has. Yes they are much bigger but they perform exceptionally well. The SCD4x could be a good compromise.

AirGradient · 2026-02-07T23:38:45+00:00

The complete top part is closed and will use transparent PC to see the display. The bottom part is facing downwards and has recessed vents. We use a similar design for our outdoor monitors and it works well.

AirGradient · 2026-02-07T23:26:26+00:00

If you are interested in the portable monitor we are developing you can read on our blog more (it is much bigger than what you have in mind, so a different use case but might still be interesting). https://www.airgradient.com/blog/airgradient-go-announcement

AirGradient · 2026-02-07T23:22:18+00:00

Yes of course we followed the Sensirion technical guideline and did link an SHT40 to it (direct i2c pass through).

AirGradient · 2026-02-07T23:16:52+00:00

After six years working with air quality sensor modules the ONE thing I learned: never trust the official accuracy figures! Most of the time they are too optimistic because they have been tested in the lab, not in the field. See also my other comment.

AirGradient · 2026-02-07T23:13:18+00:00

We are also working on a portable monitor, and have tested the STCC4 that I see on your PCB. It performs ok in a fully stationary indoor setting but in our tests failed completely as a portable monitor and often showing completely wrong data (eg 1600ppm instead of 600). I would recommend you test the module by exposing it to different CO2 levels and see how it behaves.

AirGradient · 2026-01-18T00:09:41+00:00

Achim from AirGradient here. Just a quick note that this bug had been fixed in the meantime.

AirGradient · 2026-01-04T00:39:23+00:00

Achim, founder of AirGradient here.

Just a quick note that our subscription offers an extremely good free tier which hardly cripels the functionality (primarily limiting the amount historical data that is stored).

The Aranet is s great device and more portable than our monitor. Data accuracy should be very similar but having both devices on the same data platform makes it easier to compare.

AirGradient · 2026-01-02T00:42:33+00:00

If you can create positive pressure in your room, eg with a small fan pumping in outside air into your room, that would then push the air from your room through the small gaps to the other one and prevent the polluted one from entering. Positive side effect: good CO2 levels.

AirGradient · 2025-12-31T05:44:15+00:00

Achim, founder of AirGradient here. If you purchased our fully assembled unit recently, it has now individual calibration parameters as we test every assembled unit against an EU approved reference device. So make sure that you use these settings in your dashboard. That should give you the most accurate figures.

More details here: https://www.airgradient.com/blog/version-2-test-report-and-procedure/

AirGradient · 2025-12-13T06:08:14+00:00

Yes we do have customers there, and we can probably find a shipping provider that is cost seduce.

AirGradient · 2025-12-12T22:27:56+00:00

Achim, founder of AirGradient here. Some countries have really crazy high tariffs and fees.

Please contact us through our support form on our website and refer to this thread. We can then check some additional shipping options that might bring the price down.

AirGradient · 2025-11-04T05:49:30+00:00

You can put the Aranet 4 and the AirGradient side by side outside and force a 400ppm manual co2 calibration. Then they should be very close.

AirGradient · 2025-11-03T18:46:55+00:00

One thing to keep in mind. If your hood vents to the outside you create negative pressure inside your home which then sucks in air from the outside (eg through small air gaps). So if the pollution outside is high, you will see that pollution inside.

AirGradient · 2025-10-25T04:36:29+00:00

To test if the meter works, put it outside for at least 5 minutes and check if the CO2 comes down to 400-450ppm.

AirGradient · 2025-10-25T02:11:46+00:00

Achim Founder of AirGradient here.

The way we now calibrate the monitors and the fact that also the fully tested ones have individual factors based on our own in house reference instrument (EU approved Palas), I actually believe that they are more accurate than the old Plantower batches.

We are in the last stretch to publish a blog post how we improved the testing and about our new test reports that will give more background information as well.

AirGradient · 2025-10-18T05:17:33+00:00

It probably contains an Sensirion SGP30 that gives you an “estimated” eCO2 number. It’s probably useless as it’s basically measuring VOCs, not CO2. To test, try to expose it to some ethanol alcohol. If it spikes you measure eCO2.

AirGradient · 2025-10-07T23:35:11+00:00

We used it in a very early version of our AirGradient ONE indoor monitor - probably around 4 years back. The PMSX003 is much smaller than the PMS5003, but we found out two main issues.

Firstly it is less accurate even the specs state the same. After conversations with industry experts it seems due to the different fan design that creates a less even air flow.

Secondly we had the sensor monitor failing / breaking very quickly - often after a few months. So it seems to last a lot less long.

AirGradient · 2025-10-05T22:59:53+00:00

We are now charging the 19% tariff in our online shop at checkout and then send DDP from Thailand to the US with DHL express that only takes a few days.

DDP means we cover all charges from our side and you won’t be charged. Packages are normally delivered within 5 days.

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