Where should I place the Aranet4 device in the room?

Aranet4 sensor can be used to measure air quality in places such as your bedroom or living room, kid’s room, workspace, classroom, conference room, café, concert hall, museum or any other indoor area which you would like to know the air quality of.


Aranet4 can be placed anywhere in the room where you tend to spend a lot of time in – on a surface, or mounted on the wall where it can be comfortably seen. Since people and animals exhale CO2 the readings can be momentarily higher if you breathe directly on the sensor so holding the sensor in your hand can sometimes give a higher measurement. However placing the sensor near a window or entrance door might give a slightly lower reading because of the airflow in these areas.


Aranet4 should not be placed in direct sunlight or in areas with a risk of splashing the sensor with different liquids, or high-humidity environments (higher than 85%) such as your bathroom. Place the sensor in a safe place where it cannot accidentally be dropped because it isn’t drop-proof.

The device shows that CO2 level in the room is unhealthy. What should I do in order to improve the airflow?

Aranet4 sensor warns when the CO2 level in the room isn’t optimal for your health and you should take care of the airflow in the room. You can immediately improve the CO2 level in the space you are in by taking the following steps:


• Open a window allowing fresh air to flow into the room. For the best airflow it is recommended to open windows on two different sides of the room.


• Remove any obstructions in front of the windows such as heavy curtains, blinds or furniture that can stop the airflow.


• Open the entrance door and/or door to the connecting rooms.


• Open the window or windows in connecting rooms and leave the door open for at least 10 minutes or until the CO2 level returns to an optimal level (below 1000ppm).


• Turn on the ventilation. Check that the vents are open and there are no blockages in the ducts. Schedule maintenance if there are any issues.


• If you are using air filters, make sure that they are changed according to recommendations.


• Make sure that the HVAC system is working properly; schedule maintenance if there are any issues. Air conditioners and heaters can also improve the airflow in the house, however these options may require greater energy consumption.


• Turn on the ceiling fan to increase air circulation. You can also place a portable fan in front of an open window to help the fresh air flow in better in the room. If there is no possibility of doing any of the aforementioned steps, make sure not to spend prolonged time in the area – take breaks and go out in fresh air whenever you can.

Are Aranet4 default settings available anywhere?

Aranet4 is calibrated in factory and it works instantly when it you take it out of box and insert the batteries – no additional setup is needed. These are the default settings of the Aranet4 device:


1) default measurement interval is set to 5 minutes;
2) CO2 sensor automatic calibration is disabled;
3) default temperature measurement units are set to Celsius;
4) Bluetooth connection is enabled;
5) Bluetooth connection transmission range is set to normal;
6) Buzzer for audio sound alarm notifications is disabled;
7) CO2 indication is set to human mode;
8) Access to Homey Smart Home assistant is enabled.


The 2nd, 3rd and 4th setting can be changed with the switches in the battery compartment on the back of the device, but the remaining five settings can only be changed via the Aranet4 phone application.

Can I use Aranet4 to measure the air quality outdoors?

Aranet4 is an indoor air quality sensor and therefore it’s designed to function the best when it’s inside.


If you happen to take your Aranet4 outside to measure the air quality or do a calibration of the sensor, please note that the device is neither waterproof, nor it should be placed in direct sunlight. The operating temperature of the sensor is 0°C to 50°C (32°F to 122°F) so it is not recommended to take Aranet4 outside in the wintertime when it’s freezing because it can permanently damage the sensor.

What measurements are available on Aranet4? Where can I see the atmospheric pressure reading?

Aranet4 measures four environmental parameters of air: CO2 (carbon dioxide) level, temperature, relative humidity and atmospheric pressure.


First three of the measurements are displayed on the screen of the device, and you can find the atmospheric pressure reading in the Aranet4 app.

What is the measurement unit of CO2 parameter? What is the meaning of the color indicator below CO2 level on the screen?

The three color dots indicate CO2 level in the air. The CO2 level is measured in parts per million (ppm) letting you know when you should increase the airflow of fresh air in the room.


Green – good (below 1000 ppm). Optimal indoor air quality


Yellow – average (1000 ppm). Brain cognitive function lowers by 15%.


Red – unhealthy (1400 ppm). Brain cognitive function drops by 50%

What is the NDIR sensor and why is it preferred over other types of sensors?

Aranet4 uses non-dispersive infrared (NDIR) sensor for measuring the CO2 level. The device has a small gas chamber with infrared light source in which CO2 absorbs the light. An optical filter in front of a detector then filters all of the light except the wavelength that the CO2 molecules can absorb so a precise measurement of the CO2 level can be made.



This type of CO2 reading provides a higher precision than regular electrochemical sensors because carbon dioxide is uniquely detectable with no interference from other gasses. Besides that the lifespan of the NDIR sensor is much longer because there is no deterioration or “burnout” of the sensor itself, and less recalibration is needed.

How long is the warranty period of the Aranet4 device?

The warranty period of Aranet4 is 2 years.

Can Aranet4 device be damaged if I put the batteries in the wrong way (opposite polarization) in the battery compartment?

Yes, putting the batteries in the Aranet4 device battery compartment in reverse (opposite + / -polarization) will instantly and permanently damage the device hardware. In order to repair the device, please fill in RMA form. The free two-year warranty doesn`t apply to this kind of damage.

What is the expected lifespan of the Aranet4 device?

Excluding the batteries the NDIR sensor itself can last up to 15 years. The battery life of two AA batteries that the device uses is up to 2 years at 20°C / 68°F. The batteries can last up to 2 years only if Aranet4 is used as a stand-alone device without Bluetooth Low Energy (BLE) connection to phone application and data measurement refresh interval of the device is set to 10 minutes.

In what conditions does the battery life last 2 years?

Batteries can last up to 2 years only if Aranet4 is used as stand-alone device without Bluetooth Low Energy (BLE) connection to phone app and with the device data measurement refresh interval set to 10 minutes.

Measurement interval, minutes Battery lifespan
10 2 years
5 1.5 years
2 7.5 months
1 4 months

Does using the Aranet4 in automatic calibration mode discharge the batteries of the device faster?

No, the expected battery lifespan is the same.

Batteries of device discharge in couple of days. Is it normal?

It isn’t a normal occurrence – the batteries should not discharge in a couple of days. If this happens to your device, try replacing the batteries and if the problem still persists fill the RMA form for the repair return.

Is Aranet drop proof?

Aranet4 is not impact resistant – dropping it on the ground or subjecting it to strong mechanical impact can permanently damage the sensor. The standard Aranet4 warranty doesn’t cover accidental damage such as dropping the device.

Is Aranet4 waterproof? Can I use additional waterproof box with Aranet4?

Aranet4 is not waterproof and should not be used in environments with high humidity (higher than 85%). Using additional waterproof box is also not recommended as it could make measurements delayed and incorrect.

How can I calibrate my Aranet4?

Aranet4 can be calibrated either automatically or manually at home.


In the case of automatic calibration mode, the Aranet4 device needs to be exposed to fresh air at around 420 ppm (for instance, outdoors or in a room with good air exchange) for approximately 8 hours during each 30 day operation period.


When doing a manual calibration the Aranet4 device must be exposed to fresh air (about 420 ppm of CO2) and the environment should be stable (not changing) for 30 minutes while the calibration is done. Maintain a distance of at least 1 meter from the device during the calibration process so the CO2 from your breath wouldn’t impede the calibration. To initiate the manual CO2 calibration change the switch position at the back of the device behind the batteries from MANUAL to AUTO and back to MANUAL (maintain maximum of 1 second between each movement). The calibration progress will be displayed on the screen of the device. In case of a calibration failure message, make sure that the environment requirements are met and repeat the process from the beginning.


Manual calibration can be done using the Aranet4 app as well. You can see the instructions of how to do the manual calibration via the app in the Aranet4 Calibration Tutorial.

My Aranet4 device shows high CO2 values when cooking food indoors near the device. Are the measurements correct? Does the smoke from the cooking contribute to CO2 level?

Aranet4 will show increased CO2 values when food is cooked on gas stove because carbon dioxide forms in the burning process of natural gas.

Which smart devices is the Aranet4 compatible with?

Aranet4 is compatible with most mobile devices.


Your mobile phone must have either Android 6.0 or newer or iOS 11.0 or newer (for iPhone) in order for you to be able to download the app.

Does Aranet4 support IFTTT service?

No, currently Aranet4 does not support IFTTT.

For DIY integrations using Bluetooth Low Energy you can use:

Aranet4 Python client and library

Progressive web app which supports Aranet4 using Web Bluetooth API

In the settings of the Aranet4 app Homey integration option can be enabled. What is Homey?

Homey is a smart home system that allows for integration with the Aranet4 device. You can view data from your Aranet4 devices in the Homey system. Bluetooth connection is used in communication between both devices. Homey system can save up to 10 years of historic measurement data for connected devices including Aranet4.

Where can I download the Aranet4 app?

The Aranet4 app for iPhone is available on the App Store. The Aranet4 app for Android is available on Google Play.

When launching Aranet4 application after installation on Android phones it asks to allow access to device's location. Is it really necessary?

Access to the device’s location information is a general requirement from Android operation system developers for Bluetooth Low Energy applications to work correctly. Read more»

Why does the Aranet4 app ask for permission to access Bluetooth service on the phone?

The Aranet4 app needs this access because measurement data from Aranet4 device is sent to application via Bluetooth connection.


Bluetooth connection is also used:

1) to view and change device settings (measurement interval, buzzer  settings, CO2 indication mode, Bluetooth range, Homey integration);

2) to start CO2 calibration on your Aranet4;

3) to update the device firmware version.

During the installation process the Aranet4 app asks for consent for sending diagnostic data. Which of my data will be sent?

Two types of diagnostic data can be sent:

1) crash reports in case the app has been terminated by phone operating system under some running conditions;

2) usage statistics of the individual pages, sections or screens of the app.

Is it really necessary to update the Aranet4 app to the latest version?

Updating the app is highly recommended.  The operation and functionality of Aranet4 is constantly being improved and these upgrades are implemented in the latest versions of the app. App updates also contain Aranet4 device firmware updates which should also be updated to the latest version.

How can I update Aranet4 device firmware?

  1. Open the Aranet4 app;
  2. Click on the Aranet4 device that you would like to update;
  3. Click on settings “wheel” icon on the record of the device;
  4. Open the firmware tab;
  5. The app will prompt you to start an update when a newer version of firmware is available;
  6. Confirm the update by clicking update button on the pop-up window;
  7. Wait until the update process has finished;
  8. Confirm the finished update by clicking OK on the pop-up window;
  9. The result of the update can be checked on the same firmware tab of device settings.

Where is the measurement data of Aranet4 stored - on the device or on Aranet4 app?

Aranet4 measurement data is stored on the Aranet4 device.

How long does the Aranet4 device store historic data?

The amount of the stored historic measurement data depends on the measurement interval of the device:

Measurement interval, minutes Historic data availability, days
2, 5, 10 7
1 3.5

Can I pair my smart phone with more than one Aranet4? What is the limit of Aranet4 devices that can be paired to a single phone?

Yes, you can pair multiple Aranet4 devices to your phone / Aranet4 app. Unlimited number of Aranet4 devices can be paired to a single smart device – for example if you want to have an Aranet4 air quality sensor in multiple rooms of your house.

Can Aranet4 be accessed remotely from Internet?

Unfortunately this function is not currently available for Aranet4 HOME. You can pair Aranet4 PRO with Aranet PRO base station and then see Aranet4 measurements remotely on Aranet PRO base station. Read more»

Can I manually refresh Aranet4 measurement data from the application?

Manual refreshing of the measurement data isn’t possible on the current version of the app. However our team is working on creating this function in the future versions of the app. To get an immediate update of the data you can restart the app or your phone.

A brand new out of the box Aranet4 shows below 400 ppm. Is that correct? What can I do?

The Aranet4 device is calibrated at the factory, however you can perform CO2 calibration manually if you feel that the reading of the sensor might not show an accurate number. See the previous answer to How can I calibrate my Aranet4?

What to do when Aranet4 app on Apple iOS devices shows that Bluetooth seems to be disabled and it is not possible to pair a new Aranet4 device with the app?

  1. Check whether Bluetooth is enabled on the Bluetooth settings of the iOS device;
  2. Check whether new Bluetooth connections are allowed in iOS device Bluetooth settings (Bluetooth icon in iOS Control Center menu should be colored blue);
  3. Check whether Aranet4 app allows access to Bluetooth connection.

Why is Bluetooth pairing taking so long? Why didn’t I get a PIN request on my phone?

Bluetooth pairing usually takes about 10 to 15 seconds. If it takes more than 60 seconds or an error message appears on the screen of the device the pairing process likely has crashed.


Try to restart your phone, re-open the app and repeat the pairing process. See the video How to Pair Aranet4 with a Smartphone App.

Aranet4 application measurement data does not update on Apple iOS devices, also the historic measurement data are not loading, settings cannot be changed and device calibration can not be started. What can I do?

The problem with Aranet4 app and iOS devices occurs when the connection between Aranet4 application and Aranet4 device crashes.

To solve the problem restart the app. Watch a video on How to Restart an App.

After daylight saving time change historic data in Aranet4 application has incorrect time indication. What can be done?

The problem is due to a software bug in Aranet4 application, but it is fixed in app version 1.18 and Aranet4 device firmware version 0.3.6 included in it.

To fix the problem:

  1. update Aranet4 application on Your device;
  2. update Aranet4 device firmware as described in previous answer to How can I update Aranet4 device firmware?

On Samsung Galaxy S8 phones historic measurement data in Aranet4 application does not fully load in graphs section and data sharing function does not work. What can I do?

Problem occurs when phone Bluetooth cache data gets corrupted. To fix the problem clear Bluetooth cache on the phone according to Samsung recommendations.

There is an error message on the Aranet4 screen. What does it mean?

There are following error messages that can appear on the screen of the device:


Error Code Solution
0x8001 – 0x8005

0x800E – 0xFFFE

Fill the RMA form
0x8106 or

0ppm or 9999ppm

  1. Manually re-calibrate the CO2 sensor
  2. If the problem persists, fill the RMA form
Magnetic Latvia Export and innovation award 2019 – innovative product
© 2019, SAF Tehnika AS, All Rights Reserved.
Manufactured in the EU.
Aranet offers industrial IoT environmental monitoring solutions for a diverse range of businesses, making it easy to collect and analyze real time data. Aranet is designed and manufactured by SAF Tehnika.
Magnetic Latvia Export and innovation award 2019 – innovative product
Magnetic Latvia Export and innovation award 2019 – innovative product
Aranet4 HOME is also avalaible on
Aranet offers industrial IoT environmental monitoring solutions for a diverse range of businesses, making it easy to collect and analyze real time data.
Aranet is designed and manufactured by SAF Tehnika.
© 2019, SAF Tehnika AS, All Rights Reserved. Manufactured in the EU.