ITH-20R Review Air Quality Monitor Thermometer & Hygrometer

Review of Thermometer-hygrometer ITH-20R with three external sensors 2022.  In this review I will tell you about an interesting device that will allow simultaneous monitoring of temperature and humidity in different residential (and not so) premises, on the street and in other places. We will talk about the ITH-20R thermometer-hygrometer with three wireless remote sensors and wired sensors.

Buy ITH-20R Air Quality Monitor Thermometer & Hygrometer on Aliexpress

A device with so many sensors and sensors will be useful, for example, in the country, when you need to simultaneously monitor the temperature and humidity in the house, in the basement, in the bathhouse, shed, on the street, etc.

The ITH-20R set with three sensors is supplied in two boxes, one contains the station itself and one sensor, and the second contains the remaining two:

Everything is very neat and well packaged, it’s nice to take it in hand:

The complete set consists of the following elements: the main unit with a display, 3 remote sensors, 3 wired probe probes to the sensors, a pair of small screwdrivers, instructions (in English):


  • Model: ITH-20R
  • Maximum number of connected sensors: 3
  • Method of communication with sensors: radio channel 433 MHz
  • Temperature measurement range for main unit: -20 ° C ~ 60 ° C
  • Humidity measurement range for main unit: 10% ~ 95%
  • Temperature measurement range for external sensor: -40 ° C ~ 70 ° C
  • Humidity measurement range for external sensor 10% ~ 95%
  • Temperature measurement range for wired sensor: -50 ° C ~ 125 ° C
  • Temperature display accuracy: 0.1 ° C
  • Temperature measurement accuracy: ± 1.0 ° C
  • Humidity measurement accuracy: ± 5%
  • Communication distance with external sensors: up to 90m.
  • Power: 2xAAA

The main unit with LCD monitor and sensors are made of very high quality ivory-colored plastic and have the same size and shape:

On the outside of each sensor there is an LED signaling the transfer of measured data, and on the bottom there are openings for air access and a port for connecting an additional wired sensor:

The back of the main unit has a stand, battery access cover and control buttons. On the sensors, the battery compartment cover is fixed with four screws (for this, the complete screwdrivers are needed) and they can be used outdoors under a canopy (without direct rainfall). Both boxes can be hung on the wall, for this there is a special hole on top:

The stand allows you to place the monitor in the following position:

The station has three control buttons: channel selection, switching between C ° and F, displaying MIN and MAX values ​​of the recorded temperature and humidity for all sensors and sensors. Long pressing of the buttons also has the effect: you can reset all communication channels, change the mode of fixing MAX / MIN values:


Weight (without batteries):

Under the covers:

The sensor has an additional TX button, long pressing of which resets the synchronization with the main unit, if, for example, it needs to be connected to another station:

After installing the batteries in the station within 5 seconds. all symbols are displayed (display self-test):

Almost immediately, at the bottom of the display, information is displayed from the internal sensor of the main unit itself. If there are no working external sensors within the available connection distance, dashes are displayed at the top of the screen:

a small comment: in some of the photos below, the unused sectors of the display look quite noticeable, in fact, they are practically invisible to the eye, this is just a feature of the LCD display photos in natural light.

If you insert batteries into an external sensor, then in half a minute information about the temperature and humidity of its sensors starts to be displayed on the monitor display. The connection takes place over a radio channel with a frequency of 433 MHz. A total of three external sensors can be connected at the same time. To save battery and maximally long-term autonomous operation of the sensors and the main unit from batteries, the signal is transmitted from the sensors at intervals of about 40 seconds. When the sensor sends a “chunk” of data, the red LED blinks on it, and when the main unit is receiving, the receive symbol is displayed at the top of the display. On the display you can see the number of the channel to which the sensor is connected from which the data and the charge level of its batteries are displayed:

Having installed the batteries in all three sensors, I put them in a row with the main unit and let them lie down for about 10 minutes to check how much their measurement data will match:

Channel 1:

Channel 2:

Channel 3:

It can be seen that there is some discrepancy on the sensor of the second channel, but it does not exceed half a degree, and the difference in humidity by 5% with the main unit is probably due to the fact that the sensors have a “intake” of air from the bottom, and the main unit from the back housing.

The channels displayed on the display can be changed manually using the CH / R button, but if you select the CH8 channel and do not press the button anymore, the device will start, in automatic mode, sequentially at 5 seconds intervals, to display the temperature and humidity from all connected sensors and sensors. If communication with any sensor is lost (for example, the batteries are dead), then about 10 minutes after that, dashes will be shown on the display of the main unit, when displaying data from the sensor. As for the range, I carried the central unit and the external sensor to a distance of 30 meters, through 4 walls, the reception was sure nothing was lost.

In this mode, periodic packet data transmission, as well as the presence of a low-consumption LCD display, from personal experience, allow such devices to operate from one set of batteries for up to two years.

Comparison with other thermometers-hygrometers:

Note that the numbers on the ITH-20R monitor are large and easy to read. the display is LCD, the viewing angles are quite modest and there is no backlight:

Connecting external wired sensors (which are included in the kit) to the sensors, as much as 2 meters long, significantly increases the number of temperature measurement points (they do not measure humidity):

In addition, it becomes possible to measure temperature in a humid environment or even under water, because the sensors themselves are hermetically sealed:

To check the accuracy, I thrust the external sensor into my armpit and held it for about 5 minutes, the measured temperature of 36.6 ° C and higher did not rise. As you can see in the photo below, when displaying the temperature from a wired sensor connected to the sensor, the inscription “External” is displayed:

Each external sensor with a connected wired sensor transmits to the main unit both the temperature and humidity data measured by its own sensor, and the temperature from the connected wired sensor. In fact, using three sensors with three sensors and the main unit, we get in one set the ability to measure temperature at 7 (!) Points, and humidity at four.

I will add that the external unit records MIN and MAX changed values ​​from each sensor and sensor, you can choose in which mode it will remember this: only for the last 24 hours or for the entire period of “All-Time” operation (from the moment the batteries were installed). Which mode is selected is shown on the display:

The MIN and MAX function is very useful in keeping track of which maximum or minimum temperature has been recorded outside. You can also, for example, check the operation of the refrigerator by placing the sensor in the upper chamber and the sensor in the refrigerator:

Leaving for a while, we will find out how well the refrigerator does its job:

Having disassembled the sensor, you can see that the build quality is very high:

On the main board in the upper left corner there is a radio module with a sufficiently large spiral antenna, which provides a large transmission distance of the measured readings:

The temperature and humidity sensor is located on the back of the board next to the port for connecting an external wired sensor:

In general, I really liked the ITH-20R device with three external sensors and additional sensors, thoughtful and great functionality; high-quality manufacturing; the ability to measure temperature at seven different points, and humidity at four; setting storage MIN / MAX temperature; large measurement range; high transmission range of measured data (unlike similar models with BT modules), good accuracy and long-term autonomy make the device very useful for professional and home use.

Rate article
Add a Review