What options for CO2 sensor?

Hardware
30

Any scd30 should work if you wire it correctly.
Just get an esphome mcu, like nodemcu, and wire it.
Then do software setup for esphome

31

many thanks for your hint, very much appreciated. I ordered nodemcu and scd30 on aliexpress, should get them in mid Nov.

Since all of HA, EPShome and nodemcu is new for me, it will certainly take me more than 15mins :slight_smile: If you happen to have a link to a guide, it would be great.

32

This is the guide I followed:

Copy-paste template for the scd30:

33

thank you, much appreciated.

34

What about this one? “Carbon Dioxide CO2 Detector Air Quality Tester Formaldehyde Detector”

35

hell no, that does not actually detect carbon dioxide it detects VOC and fakes a CO2 level

a functional CO2 sensor, literally just the sensor component, costs at least $20 usd, and those are the cheap chinese ones. The SCD30 is the really the best price you can get for an accurate sensor with auto calibration and temp/humidity compensation. Other quality sensors are $100 to $120 (I have checked them all)

For reasons to get the SCD30 over the cheap chinese ones, see this post:

1 Like
36

I found this awesome tutorial…

sensor all the things!

https://tinkerman.cat/post/sonoff-th10-th16-sensors-displays-actuators

37

This one Tuya compliant:
CHF 51.54 49%OFF | Tuya WIFI CO2 Meter CO2 Detector PM2.5 Temperature Humidity Sensor Multifunctional Air Quality Monitor Carbon Dioxide Detector


Someone tried?
38

The listed range of detection, combined with the price range, implies an MH-Z sensor for CO2

39

There is now a Zigbee 3.0 Co2 sensor.
I haven’t yet got it to work with Home Assistant.
It shows Temp and Humidity, but not CO2, I’m guessing it needs a quirks file creating.
(ZHA Handler for Zigpy)

I’ve requested it:

1 Like
40

quite expensive at £139 !

41

Agreed, it’s a bit steep.
Naively I thought as it was zigbee 3.0 that it would just work with Home Assistant and it would be a quick easy way of monitoring.

Sadly, I’m having to learn about Quirks, but it looks hopeful that I should have it up and running very soon.
Just need to find a bit of time to install and test the Quirk that I’ve been helped to create.

42

With a lot of help. Got this added. Should be in the next home assistant release.

2 Likes
43

I am new to HASS.io (literally installed it today) and now I want to add a CO2 sensor.

I read this thread, and it helped me already. Thanks for that!

But I have still some questions left before I commit and order the parts:

  1. All MH-Z19 Sensor I can find have the MH-Z19B variant. Can anyone confirm it works now with ESPHome? @FredTheFrog seems to made it work but from the code it was not entirely clear if it was the B-Variant or not.

  2. The installation workflow (connect ESP to HASS.io computer, load code, clip on wires to connect to sensor; no soldering required as long as I order the sensor with the pre-soldered parts for clipon-wires) seems clear, but I can’t find any tutorial describing which pins exactly need to be connected to where on either the sensor or the ESP. I have no experience in this area. Maybe someone can point me into the direction of a tutorial that does cover it?

44

First, here is my working code/yaml:

esphome:
  name: co2sensor
  platform: ESP8266
  board: d1_mini_pro

wifi:
  fast_connect: true
  domain: .local
  power_save_mode: NONE
  reboot_timeout: 5min
  ssid: "mywifi"
  password: "mypassword"
  use_address: co2sensor.local

# Enable logging
logger:
  level: debug

# Connection to MHZ19
uart:
  rx_pin: D3
  tx_pin: D2
  baud_rate: 9600

sensor:
  - platform: mhz19
    co2:
      name: "MH-Z19 CO2 Value"
    update_interval: 30s
    
# Enable Home Assistant API
api:
  password: "password"

ota:
  password: "password"

Four connections/wires are required, GND/GROUND, 5VDC/POWER, plus those two UART pins, D2 and D3.
5VDC/POWER from ESP8266 connects to VCC/POWER on MHZ19.
GND/GROUND from ESP8266 connects to GND/GROUND on MHZ19.
D2 TX/TRANSMIT DATA from the ESP8266 connects to RX/RXD/RECEIVE DATA on the MHZ19.
D3 RX/RECEIVE DATA from the ESP8266 connects to TX/TXD/TRANSMIT DATA on the MHZ19.

Hope this helps!

3 Likes
45

Thanks a lot! This helps!

46

Bey the newer model MH-Z19C of the sensair S8.

47

Got it working! Thanks for your help @FredTheFrog and @TheMysteryCleanShot 2021-03-31 at 17.45.25

Went with the MH-Z19C, because I found one presoldered for cheap on eBay.

Now I just need to solder the pin headers permanently on the ESP (I hope I don’t short it in the process :grimacing:)

48

Any of you guys familiar with these multisensors?

There are several stores on Ali that sell these but it’s not really clear whether it would work with ZHA.
They are ZB 3.0 so I suppose it should work?

49

I have not worked with the devices you point out. However, from what I have read, the lower cost < USD50 CO2 devices use a CO2 estimating sensor that ‘experts’ say is less accurate. I am far from an expert, but I wanted to get a good feel for air exchange in these covid times. So I girded my credit card and got the Aranet4 device based on the reviews. It is Bluetooth not zigbee. I kind of like that fact that I can take it out of the house and see CO2 levels at other places. If you are interested in the ‘state’ accurate CO2 level monitoring and want to waste several hours, google ‘CO2 monitor COVID’ :wink: . After I purchased the Aranet4 unit, I ran across this other device that in addition to CO2 and the standard other sensors monitor Radion as well, if that is an interest. I am happy with the Aranet4 device after using for about 2 month, I have used a Eve Room for about 5 years, prior to adding the Aranet4, it only does particulates. But like Aranet, they seem to have done there homework. Links to both devices below. Good hunting, hope you find something of use :

co2
co21630×1906 149 KB

I’m not quite clear on which Airthings device to buy to get ‘all’ the reading, a bit confusing.

1 Like