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air quality

Air Quality monitors

It is several years already I trying some Air Quality monitors. And I think it is time to post some of the results. So here it is. Overview of some Air Quality monitors tested so far.

For me perfect device is the one:

  1. measure correctly
  2. measure multiple parameters
  3. display information locally
  4. has a battery and can be used as a mobile tool
  5. is an IoT device with Wi-Fi connectivity and mobile app
  6. not cost a fortune
  7. quiet

Some of the requirements are cannot (or at least not easy to) be met simultaneously. A lot of advanced sensors with Wi-Fi connectivity and good mobile application make the device expensive. Battery and battery charging circuits usually affect temperature and relative humidity measurements. Active airflow improves measurement speed and quality but makes devices noisy. So there is no single perfect device yet to cover all Air Quality Monitor use cases. That is why I choose some devices I like more by category.

IoT Air Quality Monitors

Best IoT Air Quality Monitor “award” goes to AWAIR 2

  • ✔️Good design
  • ✔️Local data display
  • ✔️IoT device with a nice mobile application
  • ✔️Good hardware design (airflow, antennas, etc.)
  • ✔️ CO2, PM2.5, VOC, temperature, humidity
  • ❌Not all sensors are perfect
  • ❌No iPad application
  • ❌No battery
  • ❌Noise
  • 170-200$

So as you can see above the device is not perfect. It is noisy, that is how good airflow and better measurement quality and speed achieved. Some Sensors are not the best in class, that is how the price is lower than 200$. For more details see AWAIR 2 Review.

IoT Alternatives

uHoo

✔️ quiet, more parameters (CO, O3, NO2), iPad app
❌ expensive (330$), cheaper sensors, no local display

AirVisual Pro (Node)

✔️ large display, outdoor data for PM2.5, battery, iPad app
❌ more expensive (280$), fewer parameters (no VOC)

Netatmo Smart Home Weather Station (Urban Weather)

✔️ quiet, weather station (external t/RH module), iPad app, 180$
❌ fewer parameters (no PM2.5, no VOC), poor CO2 sensor

Air Mentor 2s

✔️ quiet, more parameters (HCHO), iPad app
❌ Bluetooth or additional hub, single color status LED, 330$

Airthings Wave Plus

✔️ quiet, Radon sensor, work from 2xAA, iPad app, 200-270$
❌ fewer parameters (no PM2.5)

Portable Monitors

Best Portable Air Quality Monitor “award” goes to K6-D

  • ✔️Several hours of battery life
  • ✔️Good Sensors
  • ✔️ CO2, PM2.5, VOC, temperature, humidity
  • ✔️ Low price ~100$
  • ❌Humidity measurements not perfect
  • ❌No connectivity
  • ❌Noise

Again, as it was with the best IoT device, this one is not perfect. It is noisy, it has no Wi-Fi/Bluetooth/etc, humidity measurements may show -10% RH on high humidity tests, but still, it is better than some others and good for the price.

Portable Alternatives

D9-H

✔️ additional HCHO Sensor
❌ less temperature/humidity accuracy, 110$

AirVisual Pro (Node)

✔️ less noisy, large display, outdoor data for PM2.5, battery, IoT
❌ more expensive (280$), fewer parameters (no VOC)

DM601A

✔️ large display
❌ wrong temperature and humidity, cheaper sensors, ~110$

HT-401

✔️ small
❌ CO2 only, ~124$ , battery sold separately, auto power-off

HT-501

✔️ PC app for data logging
❌ wrong temperature and humidity, no VOC, no PM2.5 ~80$

Airthings wave plus

✔️ quiet, Radon sensor, months of work from 2xAA
❌ fewer parameters (no PM2.5), 200-270$, single LED local status display.

Other Air Quality Monitors

Best in Most Trusted device category is Green Day AZ7788

  • ✔️Correct measurements
  • ✔️Old, but a good type of sensors
  • ✔️ Relay output
  • ❌Only C02
  • ❌No connectivity
  • ❌No battery
  • ~110$

Old school device with separate analog temperature and humidity sensors, Old model of CO2 sensor. No other air quality sensors present. Need to be always plugged. But still one of the best in measurement quality.

Categories
air quality

DM601

Dienmern DM601 is a portable air quality monitor with two options available DM601A and DM601B. The difference is in additional HCHO sensors. Model DM601A has no HCHO sensor onboard.

The device has SHT30 temperature and humidity sensor but measures temperature wrongly due to device self-heating and poor thermal design (see thermal photos of DM601A). The battery is 3000 mAh that gives about 5 hours of both charging time and battery life (see details).

Most of the sensors inside DM601 are unbranded. No Wireless connectivity. Usability is average. Measurements (except temperature) are more or less ok.

Aliexpress price: 70$-100$

Categories
air quality

Air Mentor 2s

Multi-sensor (CO2, PM2.5, TVOC, HCHO) air quality monitor with Bluetooth and Wi-Fi.

Applications are available for iPhone, iPad, Android phones.

Air Mentor 2 iPad application

By its design Air Mentor is not a portable IoT device. It has no battery. It has no display. So it is an alternative to uHoo (and to some extent to Netatmo). If compare Air Mentor 2s to uHoo: Air Mentor 2s have HCHO sensor. But uHoo measures CO, O3, NO2, pressure instead. Netatmo is actually a weather station with an external t/RH sensor, that also measures air quality by CO2 parameter only. Air Mentor 2s got a more expensive CO2 and t/RH sensors than both Netatmo and uHoo.

Temperature and Humidity sensor (SHT30) is both good itself and placed correctly on the bottom of the device with some gap from the mainboard. More or less as it is recommended by the Sensirion guide.

There are some issues with the current versions of mobile applications. For example, you cannot connect the device to Wi-Fi access points using iOS devices (it works using the Android version). Russian localization is not complete. Trend data from cloud not always loading (for both iOS and Android).

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air quality

Hti HT-401 CO2 Meter

Hti HT-401 is the most portable CO2 meter I have. It is small and simple. It is only 75 mm in diameter and 25 mm in depth. Weight is 62 g. That is including 14250 (1/2AA) 300 mAh battery. Its only button is power. It count 30 seconds before actually show the CO2 level. And it automatically power off after 30 minutes.

HT-401 CO2 Meter

Four-digits LED display only shows CO2 level and 3 emoticons 🙂<600ppm 😐600-1200ppm 🙁>1200. That is it. No settings for emoticons limits. No setting for the power-off timer. Not display temperature and humidity, nor time and date. Just one sensor inside and that is well known SenseAir S8 LP. That provides correct readings. Changing the environments not impact accuracy. The device is relatively cheap (I bought it for about 75$ without battery on Aliexpress)

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air quality

D9 Air Quality Detector

This time OCRKJ D9-H. Which also can be found in some shops as unbranded LCD Digital Air Quality Monitor (AKA monllac, AgoHike, Robincure). Similar to OCRKJ K6-D from the previous review. It was bought for about 100$. Yet another portable device with 10 hours battery life and correct CO2 measurements.

D9 Air Quality detector

Pros

  • 3000 mAh battery ( 10 hours of battery life)
  • additional sensors (HCHO, VOC and PM2.5)
  • 16 different screens including trends
  • Active airflow with the relatively quiet fan
  • quality design and schematic inside (no glues, connectors, replaceable sensors)
  • good CO2 sensor inside – SenseAir S8 LP

Cons

  • slow charging – 8 hours (in operation mode)
  • no connectivity (Bluetooth, wi-fi, USB mass storage)
  • no ambient light sensor
  • unconfigurable high CO2 limits (GOOD is up to 1000 ppm)
  • wrong temperature and RH measurements (+3C, -10%RH)

It looks like relatively cheap SHT20 temperature and humidity sensor inside make it sort of a lottery if you will get correct measurements or not.

See device insides: https://wiki.liutyi.info/display/CO2/D9+Inside

SALE Price was: 102$

Categories
air quality

K6 Air Quality Detector

I was not expecting much ordering KKMOON K6 (and receiving actually OCRKJ K6). Which also known as CAFU K6. Because most of the portable air quality monitors I got before have at least one major issue with measurements (AiRead M3 – all measurements wrong, HT-501 – wrong temperature, AirRadio A6 – issues with CO2 measurement after outdoor use and wrong humidity measurements). AirVisual Node was the only exception that both portable and show correct numbers. But it just too big to put it in your pocket. So there was a long history of portable CO2 monitors with issues. And it was kind of a surprise that the device I bought for 83$ is both portable and displays more or less correct numbers.

OCRKJ K6 Air Quality Detector

Pros

  • 3000 mAh battery ( 10 hours of battery life)
  • additional sensors (VOC, PM2.5)
  • correct t, RH and CO2 measurements (not sure about other)
  • 16 different screens including trends
  • Active airflow with the relatively quiet fan
  • quality design and schematic inside (no glues, connectors, replaceable sensors)
  • good CO2 sensor inside – SenseAir S8 LP

Cons

  • slow charging – 8 hours (in operation mode)
  • no connectivity (Bluetooth, wi-fi, USB mass storage) – nothing
  • no ambient light sensor
  • unconfigurable high CO2 limits (GOOD is up to 1000 ppm)

See device insides: https://wiki.liutyi.info/display/CO2/K6+Inside

Price: ~100$ (sale price was 83$)

Categories
air quality

Awair 2

Awair 2-nd edition is a better version of Awair, that fix some known issues of first edition

Awair 2
Awair 2-nd edition

What was fixed and added

  • 24h time format
  • USB Type-C standard 5v power connector
  • USB 5v 2A standard power supply
  • Better display (resolution, no backlight)
  • Ambient light sensor (display auto brightness)
  • Microphone (not sure if it is good to have it on IoT device)
  • Better PM2.5 sensor
  • New buttons to switch the display mode
  • Better wireless connectivity (new antennas)
  • Better (active) airflow
Categories
air quality

XINTEST HT-501 CO2 Meter

Portable CO2 meter and data logger with battery and good CO2 sensor inside.

Xintest HT-501

The only really wrong thing about this device is it always show temperature higher than it is for about 2°C (for example 28.0°C instead of 26.0°C) and it is not something related to wrong sensor placement.

Pros

  • Portable
  • 20h work from a battery
  • LCD Color zoning
  • Datalogger
  • Setup time and alarms from PC
  • Sensair S8 CO2 sensor

Cons

  • Incorrect temperature measurements
  • No time and date on the screen
  • 30 sec warmup time
Categories
air quality

uHoo

uHoo – most advanced air quality monitor, at least if consider a number of sensors. Including advanced sensor like CO, CO2, PM2.5, VOC, O3, NO2. And also traditional like temperature, humidity, and air pressure.  Measurements look accurate enough.

uHoo and iPhone

The device does not have any local indicators. Not a single color LED to show air quality status. The only way it communicates with the world is Wi-Fi and mobile application. The application (v 3.8) or backend infrastructure that makes it work is unfortunately unstable. Also, an interface is poorly adapted to iPhone X.

uHoo is not portable due to many reasons like no local indication, no battery, need Wi-Fi (and new connection setup will take time).

Categories
air quality

Green Day CO2 Monitor

One of the oldest devices I got for CO2 monitoring is AZ-7788 GreenDay. It is 4 years old now. The device is still good and accurate.

Green Day

Used as portable mostly because it has an LCD and not require setup.