Unaligned readings of CO2 and humidity from new weather stat

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thorre
Posts: 4
Joined: 27 Jun 2014, 20:35

Unaligned readings of CO2 and humidity from new weather stat

Post by thorre »

I have had my station for a couple of days now and have a serious problem with the indoor sensors. I have two of them, the main station and an additional one that I purchased separately. Both are located on a table right now within a couple of centimeters from each other. They have been placed like this for about 48 hours because I got some strange readings and wanted to verify if they are calibrated in the same way which they are _not_.
I have tried to remove the power source of both the primary and secondary indoor module for approximately 10 minutes and have also initiated a manual calibration.

Symptoms:
Temperature readings are within 0.5 degrees C which is really good.
CO2 differs 324 between the stations (which are only a few centimeters apart from each other). This is really bad since the specs are +- 50 ppm.
Humidity differs 10% between the stations which is bad.
Is there a way to do manual calibration via a cli/api or other procedure?

I am disappointed by the big deviation of the CO2 readings since this was one of the main selling points for me :cry:

I have tried contacting netatmo via their web-form but have not recieved an answer as of now .....

More information can be found here: https://drive.google.com/file/d/0B3muP8 ... sp=sharing

Thanks for your time
/thorsten
scratch1965
Posts: 1
Joined: 29 Jun 2014, 17:14

Re: Unaligned readings of CO2 and humidity from new weather

Post by scratch1965 »

I have more or less the same issues. I have one base module, one outdoor and two indoor modules.
The CO2 readings are all over the place for all modules.
The temp. readings are not as good as yours, but the difference is acceptable, although the Base station is way out, compare to the other three.
Humidity between 3 modules are within 2%, but more than 5% difference compared to the base station. What i also noticed is that the humidity has never been below 55%, even on really hot dry days!
Temp. can be "calibrated" in the settings, but there is nothing you can do for humidity (as far as I know).
daysofwonder
Posts: 2
Joined: 02 Jul 2014, 10:38

Re: Unaligned readings of CO2 and humidity from new weather

Post by daysofwonder »

I bought an additional indoor module this week. Same thing here. As mentioned above, the temperature can be calibrated in the settings section, but I am completely disappointed by the CO2 values! Right now: 366 ppm and 591 ppm. I started the calibration once more this morning, but I am afraid, it will have no effect. So it seems like You cannot trust these measurements. They are more or less estimates. :-(
thorre
Posts: 4
Joined: 27 Jun 2014, 20:35

Re: Unaligned readings of CO2 and humidity from new weather

Post by thorre »

I have now managed to get in contact with a technician at Netatmo via their support form on the homepage.
They have calibrated the humidity and the readings are now within 2% between the stations which is really good.
The CO2 is still off by about 300ppm between the stations but netatmo told me that they would fix that next week.
If they do I will be perfectly happy with their products.

The important thing for me is not to measure the exact presence of co2 humidity or temperature but the important thing is that all stations report the same values (if located at the same location of course) so that the measurements become comparable.
daysofwonder
Posts: 2
Joined: 02 Jul 2014, 10:38

Re: Unaligned readings of CO2 and humidity from new weather

Post by daysofwonder »

Well, I had a reply from the support, too:
"If a huge difference remains at the end of the process, please reply to
this mail and we will force another calibration method, which will last
longer but will be more precise."

But after I started a second calibration process this morning, the values are okay now - or at least nearly equal at both stations (374/394). I can't check, if they are correct.
thorre
Posts: 4
Joined: 27 Jun 2014, 20:35

Re: Unaligned readings of CO2 and humidity from new weather

Post by thorre »

My experience is that around 400 ppm the stations are quite precise when compared to each other but the difference increases in a non-linear or exponential way the higher the ppm count gets.
Duccemicke
Posts: 4
Joined: 09 Oct 2014, 16:13

Re: Unaligned readings of CO2 and humidity from new weather

Post by Duccemicke »

I also bought an additional indoor unit and placed it at the same place as my base unit (5 cm apart) for comparison. Humidity measures approx 10 % different and CO2 measures approx 100 ppm different. My guess is that the original unit (base unit) measures the CO2 correct (base = 400 ppm, additional = 300 ppm = to low) and my additional indoor unit measures the humidity correct (same values as a separate humidity meter from Woods, placed together with both Netatmo units).
Is it possible now to manually change the values on the units, to make them correspond (i e lower base unit 10 % on humidity measure and increase additional unit 100 ppm CO2 measure)?
thorre
Posts: 4
Joined: 27 Jun 2014, 20:35

Re: Unaligned readings of CO2 and humidity from new weather

Post by thorre »

Contact netatmos support. They will calibrate your devices for you.
Duccemicke
Posts: 4
Joined: 09 Oct 2014, 16:13

Re: Unaligned readings of CO2 and humidity from new weather

Post by Duccemicke »

Ok, great!
Thanks!

//Mike
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