Air Quality Monitor/Sensor

[MortarThePoint]

I am interested in getting an air quality monitor, to include a CO2 meter. Can anyone recommend one? It would be good if it could measure:

• CO2
• Particulates (e.g. PM2.5)
• Temperature
• Humidity

Even better if it could log these, failing that Max/Min would be good as well.

 

I have found various on Amazon, but they aren't particularly popular. This one was so cheap I have bought it to take a look, but am very dubious given the low cost:

https://www.amazon.co.uk/dp/B085DJQRY1/

I'd be keen to get one I would trust a bit more though.

 

 

[Cpd]

This has been talked about before and without making something bespoke there seems to be little available on the market that represents quality / accuracy at an affordable price. 

[MortarThePoint]

13 minutes ago, Cpd said:

This has been talked about before and without making something bespoke there seems to be little available on the market that represents quality / accuracy at an affordable price. 

 

Thanks, I've started looking at various sensor modules so may end up with a bespoke system

[PeterW]

What is your budget ..? For something that does that kit you’re probably £4-600 off the shelf. 

[MortarThePoint]

Just now, PeterW said:

What is your budget ..? For something that does that kit you’re probably £4-600 off the shelf. 

 

My budget is probably up to around £175. I don't need professional grade calibrated stuff, but I don't want junk (despite having just bought a £17 one ? )

 

Looks like I may have to make my own system which is a time sink but interesting. I'd buy something now rather than waiting to make something in a couple of years time.

[Conor]

Just an FYI, any air quality sensors I've worked (esp oxygen and organics) with in the past have been unreliable and require recalibrating or replacement annually.

[PeterW]

Is there a purpose to what you want to do with it ..? Internal or external AQ..? 
 

You’re not having MVHR are you ..?

[MortarThePoint]

9 minutes ago, Conor said:

Just an FYI, any air quality sensors I've worked (esp oxygen and organics) with in the past have been unreliable and require recalibrating or replacement annually.

Yes, that is a concern. I know there has been a lot of progress in gas sensors over the past 20 years and hoped that some would have filtered down to consumer grade products. I do see some interesting IR based CO2 sensor modules for around £20 and PM2.5 ones for around £30. That's probably what I would incorporate into a homebrew one.

 

5 minutes ago, PeterW said:

Is there a purpose to what you want to do with it ..? Internal or external AQ..? 
 

You’re not having MVHR are you ..?

Yes internal AQ. We're not having MVHR but I am looking at PIV and/or dMEV and so there is scope to close the loop on air quality which MVHR would also allow. MVHR is obviously a more energy efficient approach, but we're exploring all of that on another thread.

[PeterW]

So you will need trickle vents then - AQ is uncontrollable at that point. 

[Adrian Walker]

I'm building a true CO2 meter based on the Sensirion SCD41 sensor with a Raspberry Pi.  It might also include the SGP40 VOC sensor.

Edited May 29, 2021 by Adrian Walker
Multiple entry

[MortarThePoint]

5 minutes ago, Adrian Walker said:

 

I'm building a true CO2 meter based on the Sensirion SCD41 sensor with a Raspberry Pi.  It might also include the SGP40 VOC sensor.  

 

 

 

 

 

Nice. I've used their flow sensors before and know the company to be reputable which is important

[Adrian Walker]

19 hours ago, MortarThePoint said:

Yes, that is a concern. I know there has been a lot of progress in gas sensors over the past 20 years and hoped that some would have filtered down to consumer grade products. I do see some interesting IR based CO2 sensor modules for around £20 and PM2.5 ones for around £30. That's probably what I would incorporate into a homebrew one.

 

Yes internal AQ. We're not having MVHR but I am looking at PIV and/or dMEV and so there is scope to close the loop on air quality which MVHR would also allow. MVHR is obviously a more energy efficient approach, but we're exploring all of that on another thread.

 

 

Have a look at the Sensirion SCD41 sensor - https://www.sensirion.com/en/environmental-sensors/carbon-dioxide-sensors/carbon-dioxide-sensor-scd4x/

[MortarThePoint]

8 minutes ago, Adrian Walker said:

 

I'm building a true CO2 meter based on the Sensirion SCD41 sensor with a Raspberry Pi.  It might also include the SGP40 VOC sensor.  

 

 

 

 

 

Nice. I've used their flow sensors before and know the company to be reputable which is important

[Adrian Walker]

4 minutes ago, MortarThePoint said:

 

Nice. I've used their flow sensors before and know the company to be reputable which is important

 

It's nice and small and uses photoacoustic sensing principle, that's the development board sitting on my Apple keyboard

Edited May 29, 2021 by Adrian Walker

[Nick Laslett]

I have just had this recommended to me. Just C02, temp and humidity, not particulates. A bit pricey at €169 euros. 
 

https://aranet.com/en/pro/products/aranet4-home

 

I believe it integrates with Home Assistant. They have a separate PM sensor. 
 

I probably don’t need it, I would use it for C02. But do find these kind of measurements interesting.

Edited September 11 by Nick Laslett

[SteamyTea]

1 hour ago, Nick Laslett said:

But do find these kind of measurements interesting

Why not use a home made one.

 

[joe90]

1 minute ago, SteamyTea said:

Why not use a home made one.

 

Not everyone would know how to make one, I always said I thought MVHR should run on a co2 detector but I know it’s related to RH.

[Adrian Walker]

12 hours ago, joe90 said:

Not everyone would know how to make one, I always said I thought MVHR should run on a co2 detector but I know it’s related to RH.

Measuring/monitoring CO2 is the best way to check that your MVHR is running properly.

[SteamyTea]

4 minutes ago, Adrian Walker said:

Measuring/monitoring CO2 is the best way to check that your MVHR is running properly.

I would have thought that checking the room flow rates and keeping the filters clean would be the best way.

[Adrian Walker]

3 minutes ago, SteamyTea said:

I would have thought that checking the room flow rates and keeping the filters clean would be the best way.

That assumes that the flow rates are correct. IMHO most MVHR systems are not commissioned properly.

[SteamyTea]

Say you considered the CO₂ levels too high, apart from increasing that rooms ACH, not much else can be done about it.

[joe90]

53 minutes ago, SteamyTea said:

I would have thought that checking the room flow rates and keeping the filters clean would be the best way.

That wont account for whether there are many or no people in the house, windows/doors open. A bit like central heating being controlled by room stats not flow temp from the boiler only.

Edited September 12 by joe90

[Kelvin]

I fitted Deka CO₂ monitors in each bedroom and the study so four of our rooms are monitored. They record current level, 8 and 24hr average and 24hr peak. 
 

Google says: 

 

I couldn’t sleep last night so used the small guest bedroom. 

 

Guest bed ( 1 occupant small room low ceiling window closed) - 8hr average - 789ppm 24hr peak 906ppm

Master bed (1 occupant large room high ceiling Velux trickle vent open) - 8hr avg - 540ppm 24hr peak 625 ppm 

 

Upstairs sitting room (unoccupied large room high ceiling Velux trickle vent open) - 8hr avg 345ppm 24hr peak 503ppm - monitor is beside a wall mirror that other half uses to get ready for work

 

Study (medium sized room low ceiling variously occupied throughout day window closed) - 8hr avg 402ppm 24hr peak 473ppm

The guest bed has peaked much higher than that when we’ve had two people sleeping in it so I open the window.