CO2 sensor recommendation

These people make CO2 sensors using IR absorption. They are very low power and I believe are priced between the two sources you've found.

(I have an interest in these parts since I do some work for the company who makes them.)

https://www.gassensing.co.uk/

MK

I have used the sensors Michael's referring to in commercial designs. They are very nice to design with and are already calibrated.

Thank you for this tip. I went through their portfolio and seems good.

I also opened a few datasheets and I have to say I haven't seen such short datasheets like they provide Sensors communicate over UART, however, there is no communication scheme mentioned, hmmm...

I will contact them about more details and availability, I haven't found their products in any distributor's portfolio.

AMS has the CCS811, which does CO2 and VCO measurements. Its used on the Thunderboard Sense board, which might also be of interest for your project.

You might check out the Senseair S8.

They are self-calibrating and last about 15 years at a cost of about $50.

http://www.senseair.com/products/oem-modules/senseair-s8/

http://www.co2meters.com/Documentation/Datasheets/DS-S8-3.2.pdf

I think one was used by janisalnis on a project here:

In-the-Air-Challenge: Exploring internally NDIR CO2 monitor

K30 CO2 Sensor is one I have running full time in my room (part of my LivPi). It auto calibrates using an interesting method. Its also not to costly for a full module (depending on your idea of costly I guess). I have tried to compare it to the AMS one and the AMS was reading weird numbers (it is connected to a Silabs board I got). In the end I trust my K30 pretty much all the time and I have seen it deployed in commercial units for building monitoring systems.

Kas

Thank you for all your ideas and for pointing me towards some interesting reading and products. I only need a piece or two for start, so anything between ca. €20-80 is OK for me.

I have already stumbled upon SenseAir sensors, however, they also seem to be unknown to EU/US component distributors. It is apparently easier to get their Sensors reselled through eBay from China/Taiwan, than to find them in a store in EU (When possible, I prefer local producers and stores to overseas ones - that relates to everything I buy, not just electronics.) I will try to contact them via email about the availability and price.

I'm also looking forward to seeing Sensirion's products, they have been teasing for a few months now with CO2 sensor and Multi-pixel gas sensor. I use their SHT31 and SHT21 as home thermometers and humidity sensors and they perform great.

For now, the Thunderboard Sense board seems to be my winner (regarding availability). I will probably order it with Silicon Labs Sensor Puck to try measuring blood oxygen levels.

koudelad

I would be very interested in your results with this board. This is the SiLabs board I was referring to when I mentioned was having odd readings. In all fairness I had other issues with this board. Maybe if I have some time freed up I will try playing with this board again.

Kas

SenseAir is a Swedish company - they have a long list of distributors on their web site..

http://www.senseair.com/contact-support/distributors/

I know dougw , thank you for your time. The trouble is, no distributor is listed for the Czech Republic (or the Slovak Republic, with which we shared a lot in history). I wrote them an email and I will see, whether there is any chance to buy a piece or two directly from them (or at least be directed towards a supplier from Austria / Germany). That is why I said it is easier to buy the Thunderboard, just a matter of a few clicks for me