Air Quality: CO2 Sensor MH-Z14

[epierre]

Hello,

I have started working on the MH-Z14 which is present in the store, that is accurate (uses infrared to mesure particles) and does not evolve in time.

http://mysensors.org/store/#gas

It gives back the concentration based on a pulse modulation (PWM). Here is my first sketch attempt:

https://github.com/empierre/arduino/blob/master/CO2-MH-Z14.ino

Current status: in investigation
Discussion: The script uses the pulseIn function, but it appears that the output value is
very much more the 1004ms cycle advised:

pulseIn: 324657 ms
calculated value: 649310
324305 ms
648606
324136 ms
648268
323617 ms
647230

Anyway when I beathe on the sensor it reacts which is a good news.

I will try to spy it with a DSO to see if there is an issue.

Another way to do it would be through the UART access...

[epierre]

Hello,

I tried to see with the DSO and the pulse was good (1023ms).

Looking back to values and the pulseIn, I found this is nanosecond and not millisecond... my mistake !

So the script is validated !

[daulagari]

Nice, thanks, good to have to monitor in-house CO2 levels and global warming...

Quite an expensive sensor, what are your plans with it?

[epierre]

No special plan, it is still my quest for gas reading, from imprecise and dirt cheap MQ and like to some entry level ones that are way better ...

[BulldogLowell]

@epierre

Thanks for your work on this. I am going to build 2 for my factory in China. I make construction heaters fired by diesel, kerosene, JET-A/B, and #1/#2 heating oil. I am always concerned about the employees exposure to CO buildup, even though we employ a high capacity ventilation system.

I will let you know what the final build looks like, I envision a very high quality (machine-tool quality) build with colour changing indicator and klaxon. Something different for me, I am usually making things for my kids or the house so it has to look 'nice-ish'.

cheers!

[epierre]

@BulldogLowell said:

I am always concerned about the employees exposure to CO buildup, even though we employ a high capacity ventilation system.

I guess you meant CO2 ? I'm happy people find new use to those sketches, that is the magic of this forum ! The more basic bricks we'll have, the more usefull the use of it will be !

You can also check the Particle mesurement in air with the SamYung, I will extend it to PM1 and PM2.5:
http://forum.mysensors.org/topic/291/dust-sensor-1-4/20

[roy]

The sensor price has dropped a lot during the past years , monitor CO2 in house at 0~10000 ppm is becoming popular to remind necessary ventilation .
Using CO2 sensor module for a DIY CO2 monitor is a good choice , of course , this is a OEM products , mostly for using by factory .
See detailed at
http://www.gassensor.com.cn/product_en/typeid/9.html

[epierre]

@roy how can these be purchased ? they don't exist on aliexpress...

[roy]

@epierre I am sales manager of CO2 sensor in this company , We didn't retail CO2 sensor . Because the product is designed to built-in IAQ device , we used to cooperate with factory who need sensor on their device .

This products have MOQ reqirement .You can also send more information about your project to my email ruyi.li@gassensor.com.cn
I will see what support we can provide to you .

[epierre]

Hello,

There are projects and projects... Here I provide code for many already available sensors, and on Particle/Spark.io we are building hardware that would facilitate IAQ devices building, but it is always the end user that has to order the device, which is thus an important point.

The MOQ is thus irrelevant except if people group themselves to reach the minimum order quantity, but before that we need to make some prototypes so the code will be tested and validated for people to use it anywhere.

Tell me if this is possible to get samples in this optic,

Emmanuel

[roy]

Positive answer , we can provide samples . see available types in attachment .Which one do you preferred ?Choose the output interface and I can send communication protocol in advacne .
Just need your information to send products ,your company ,shipping address , contact name , contact phone number .Air Quality Sensor Module Product List (Wuhan Cubic-V2015.1).pdf
Regards
Roy Lee
ruyi.li@gassensor.com.cn

[epierre]

@roy any news ? I've sent you an email but did not get any answer so far...

[roy]

@epierre ，can you please send your email again, it maybe spammed by my server .

[mortommy]

Hi @epierre ,
the CO2 sensor is not available anymore in the store page. On aliexpress there are sensors from 25$ to 80$; did you test the cheapest one? Or in the meantime you have any other suggestion? I'd like to order one and make my CO2 sensor node.
Thank you.
Regards.

[epierre]

@mortommy the €23 is the same I have (I paid $70 at the time...)

[alexsh1]

@mortommy I'd strongly suggest you go for this sensor. It is expensive, but very-very precise and reliable. You can go for MQ-135 - this is what I did at the beginning. It is utterly useless and can probably be used in enclosed premises, but not in normal houses/flats as its reading are just jumping up and down.

You can go for the MH-Z19 sensor - it is not much cheaper than MH-Z14 (or MH-Z14A).

http://www.aliexpress.com/item/FREE-SHIPPING-MH-Z19-CO2-detection-sensor-module/32576013283.html?spm=2114.30010308.3.21.cLSnEB&ws_ab_test=searchweb201556_10,searchweb201602_5_10037_10017_507_10032,searchweb201603_2&btsid=ce733a29-ca27-4f2a-b438-95e3abc647b0

[mortommy]

thank you guys.

[epierre]

@alexsh1 said:

@mortommy I'd strongly suggest you go for this sensor. It is expensive, but very-very precise and reliable. You can go for MQ-135 - this is what I did at the beginning. It is utterly useless and can probably be used in enclosed premises, but not in normal houses/flats as its reading are just jumping up and down.

agreed ! that comes with experience !

You can go for the MH-Z19 sensor - it is not much cheaper than MH-Z14 (or MH-Z14A).

it is now $3 difference

[flopp]

I am playing with a MH-Z19 and found this thread and the link in the first post is not working.

This is the correct link

https://github.com/empierre/arduino/blob/master/AirQuality-CO2-MH-Z14.ino

[alowhum]

Does the MH-Z14 code work for the MH-Z19 as well?

[Daniel Linder]

@alowhum. Yes it does. I've built a combined Co2, humidity and temp sensor using mh-z19 and dht22. it shows current values on an oled and reports back to openhab. will use a number of these for ventilation control.If anyone is interested I'll post the complete build when done (currently waiting for more components from China).

[alowhum]

The downside is that it uses pulse-width modulation to get the data out. This isn't a problem, but it soes mean that you are taking a digital value, turning it into an analog voltage reading that analog voltage with Arduino, and turning it back into a digital value.

I scraped together some code for the MH-Z19 that uses a serial connection to talk to the sensor instead. The sketch can be found here.

I also highly recommend getting the BME280 sensor for your humidity needs. It even gives you barometric data, so you can have your own weather prediction. A sketch that uses that sensor, and that is very easy to combine with the MH-Z19 sketch I just posted to, can be found here.

If you also want to integrate the best-buy dust sensor, have a look at this sketch that already combines the MH-Z19 Co2 sensor and the PMS-7003 air quality (fine dust) sensor.

[Daniel Linder]

HI,
I'll try your serial interface code later.
It seems to be an accurate sensor, however - the values are a bit "bouncy". I'll incorporate a "running average" on the measurements - to calm it down.
I am always tempted to add more sensors to the nodes, but in this case it is not possible.
My casing design would not even allow for one additional resistor...

[sola]

@Daniel-Linder Hi Daniel,

I would be quite interested in your Mh-z19 and DHT22 sensor node, I am building a similar one.

Please post the build if you still have it.

Many thanks.

[reinhold]

FWIW, some weeks ago I ported the MH-Z19 code (the serial interface, by default connected to digital pins 6 and 7) to NodeManager for use in my own little gas detection node (MH-Z19 and four MQ-... sensors). The MH-Z19 code is included in the 1.6 release of NodeManager, so if you are using NodeManager for your nodes, the MH-Z19 sensor should be really easy to set up and use.

[sola]

@reinhold said in Air Quality: CO2 Sensor MH-Z14:

orted the MH-Z19 code (the serial interface, by default connected to digital pins 6 and 7) to NodeManager for use in my own little gas detection node (MH-Z19 and four MQ-... sensors). The MH-Z19 code is included in the 1.6 release of NodeManager, so if you are using NodeManager for your nodes, the MH-Z19 sensor should be really easy t

Many thanks, I will check out NodeManager, looks like some really cool stuff.

[Gelisob]

Hello guys, could somebody clear up, what sensor to prefer. MH-Z14A vs MH-Z19 ?
Their price is very similar and kinda meh in comparison but which should one prefer and when?
I can see Z19 having some response time lower but power consumption higher...
Maybe someone here already made the comparisons and can share that useful information into this thread, so that others would also know what to pick and why?

Thanks

[alowhum]

Go with the Z19. Here's some ready made code:
https://forum.mysensors.org/topic/6528/mh-z19-co2-sensor/5