Best value sensors for Carbon Monoxide and Smoke

[micah]

I've read most of the fabulous and long thread on Air Quality Sensor here in the forum.

I had a question, and I didn't post it in that thread because I didn't want to de-rail the flow, which seemed to focus a lot on calibration, examples and fabulous technical detail.

Use Case
I'm planning on making a combination device that sits on the nightstand and performs all the following:

• Alarm clock (with remote access, personalized wake-up midi songs, manual and auto snooze i.e.: if you don't get out of bed it rings again)
• Wake-up light
• Bed Occupancy Monitor (I'm going to gladly and shamelessly copy petewill's great example
• Switch/button that will turn on the room light

Since I'll have wall power for this device I figured it would be really smart to add a Carbon Monoxide and Smoke sensor capabilities, since I'm planning on making one for each of my kids two bedrooms.

So I've got a simple question, which sensor should I buy?

I'd like something relatively economical, so not this SainSmart MH-Z14 Infrared Carbon Dioxide Sensor For Arduino... lol

So should I be looking at a MQ-2, MQ-3, MQ-4, MQ-5, MQ-6, MQ-7, MQ-8, MQ-9, MQ-131, MQ-135, MQ-136, MQ-137, MQ-138, MQ-214, MQ-216, MQ-303a, MQ-306a, MQ-307a, MQ-309a, MG811, AQ-104, AQ-2, AQ-3, AQ-7.... as you can see there are lots of choices.

I think I know the right answer already, but I'd love to hear the wisdom of the much more advanced crowd here at MySensors

3... 2... 1... go!

[korttoma]

You can find the MH-Z14 for 30$ on aliexpress...

http://www.aliexpress.com/item/100-NEW-Cost-effective-infrared-carbon-dioxide-sensor-module-promotional-MH-Z14-infrared-co2-sensor-for/32363341506.html

[micah]

@korttoma thanks, but ouch, $37 CAD seems expensive, since I already have real smoke detectors in the house, and since I'm planning 3 of these devices that would be over $110

I was really hoping the answer would have been something like this MQ-9 :worried:

[alexsh1]

@micah

There is no right or wrong answer to your question. The problem is that if you go for a cheap MQ* sensor, you will have to dive into calibration etc. I have MQ-135 and I am still struggling to calibrate it properly. With MH-Z14 it is much easier, but yeah you pay the price. Ultimately, this is up to you to decide.

At this price level ($110) you can probably buy 2-3 z-wave smoke detectors and automate it with Vera or Domoticz.

[korttoma]

I agree with @alexsh1 here. I have placed a MQ-2 in the ventilation pipe to detect smoke for incoming fresh air because sometimes smoke comes in from outside through ventilation and then I want to turn of the ventilation. I have not had any luck with this because the value I receive from the MQ-2 is not reliable and it seems to depend on temperature and humidity also.

I have plans to replace it with an MH-Z14 but I have not done this yet. I don't know if this will solve my problem but I am hoping that it is a "You get what you pay for" kind of situation.

[Samuel235]

Good morning guys, I'm currently designing my full room module, I too have had to spend many hours sifting through the various sensors, below I have included my choices. I chose to go down the two sensors for smoke route, one for fast burning fires and the other for the low flame smoldering type such as furniture fires. I don't think i will be using both in each module but the footprints will be on board and that way i can have different configurations on my modules depending on which room they will be located in throughout the house to stop false alarms being created due to incorrect sensor usage.

Carbon Monoxide: ME2-CO @ $14.64 each

Photoelectric (optical) Smoke Sensor: Custom made Infrared Emitter and Receiver setup using 1 IR LED 940nm pulsing at 38Mhz with 555 timer and a IR receiver

Ionisation Smoke Sensor: MQ-2 @ £0.99 each. I will be removing them from the PCB they come on and locating them on my module board itself.

If you are interested in anything else then please don't hesitate to question me. If the question is specific for my module then drop the comment onto that topic rather than clogging this topic up ;)

Good luck and have fun sensing that dirty smoke!

[alexsh1]

@Samuel235 Very interesting. Did you consider these sensors:

(very tiny and low voltage)
http://www.figarosensor.com/feature/tgs8100.html

or

http://www.figarosensor.com/feature/tgs5042_tgs5342.html

[Samuel235]

@alexsh1, as my very in depth updates on my module topic speaks about, i did indeed. And i absolutely loved them. But i just couldn't 'easily' get a hold of them in the UK.

[alexsh1]

@Samuel235 I am based in the UK too and I found this -> http://www.soselectronic.com/?str=371&artnum=170939&name=figaro-tgs8100

[Samuel235]

And on that note, i have found the Carbon Monoxide Figaro Sensor for $22 so $8 more than the ME2-CO that i've ordered.

Then you have just found the one that i've always struggled to get my hands on, the air quality sensor. Now i'm very tempted to order one of each to trial o.O These were my intended sensors to go for but because of the fact i couldn't get my hands on them and the price of the air quality one compared to that of MQ2 is high along with the price difference on the CO sensor too.

To go with these two over the two i have on order it would cost around £16.40 more.

MQ2 & ME2-CO: £11.50
Figaro Sensors: £27.90

Time to reconsider!

[Samuel235]

I have just ordered one of each of these sensors. I will report on my module topic with the experience when they arrive.

[alexsh1]

@Samuel235 said:

I have just ordered one of each of these sensors. I will report on my module topic with the experience when they arrive.

Yeah, I see you place the order :)

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09 Apr 2016 00:07

Have you looked at the software side? Which library to use with Figaro?
I have itchy hands to get one ordered as my experience with MQ* sensors was not positive.

[Samuel235]

@alexsh1 Well, i ordered the one off of Aliexpress, but i can't get the air quality sensor that you linked. There is a 50EU spending minimum and a 8eu postage charge too. I'm not spending 50EU just for that one sensor >.<

I had a brief look at the software side before when i was contemplating purchasing these at the start of my designing. I can't remember much of it though.

[Samuel235]

@alexsh1 - I have just dropped Figaro an email direct. So lets hope we get some leads to a company/source over here. I will keep you posted if i hear anything in return :)

[alexsh1]

@Samuel235 Good lad! I was gonna drop them a note, but you were quicker than me

[Samuel235]

@alexsh1, to be honest, it might be worth you contacting them as well. I have dropped a little bit of information regarding us building modules as a community under the name of MySensors.org (I hope @hek doesn't mind), therefor by you contacting them and mentioning MySensors.org too it might show that they have some interest (which i have said to them) but the more interest that is shown, the more likely they will supply us ;)

[alexsh1]

@Samuel235 Fair enough - I'll drop them a quick line.
BTW Have you considered MH-Z14?

[Samuel235]

@alexsh1 said:

@Samuel235 Fair enough - I'll drop them a quick line.
BTW Have you considered MH-Z14?

Correct me if i'm wrong here but this is for Carbon Dioxide, right? Are you thinking this for the smoke sensor/air quality sensor?

[alexsh1]

@Samuel235 said:

@alexsh1 said:

@Samuel235 Fair enough - I'll drop them a quick line.
BTW Have you considered MH-Z14?

Correct me if i'm wrong here but this is for Carbon Dioxide, right? Are you thinking this for the smoke sensor/air quality sensor?

That's right. CO2 and temperature are the air quality parameters. This is how most companies (Withings for example) measure air quality. Obviously, it is more complicated if you want to get precise as air quality is affected by other gases, volatile organic compounds, particulates etc.

[Samuel235]

@alexsh1, If i'm honest I'm only interested in knowing if there is smoke present in the air so this might work. However, they seem to come pre-mounted to a board and they are no cheaper than anything else i have been looking at. Still seems hard to get a hold of too.