Cheap temperature and humidity sensors with a screen continue to spawn in my mailbox. I’ve accumulated 9 in total so far, writing individual reviews for each one along the way. When I hit 10, I will publish a summary and comparison article for anyone interested.
In the meantime, you can check out what I’ve tested so far:
- Tuya Climate Sensor and Alarm Clock JM-TRH-ZGB-V1
- Neo Zigbee LCD Climate Sensor NAS-TH02B2
- Zigbee Temperature & Humidity Sensor with a Screen SZ-T04
- Sonoff Temperature and Humidity SNZB-02D Review
- Moes Temperature & Humidity Sensor ZSS-KB-TH
- Tuya Backlit LCD Climate Sensor with Clock ZTH08
- Tuya Blue Climate Sensor and Clock YHZBTHP-1 Review
This time it’s an interesting looking model, white labelled Tuya ZL02-ZX. But “interesting” does not mean the device is worth buying, even if it’s only a few USD. This one cost me <$10 on AliExpress, it’s not available on Amazon.
- Model: LKTM ZL02-ZX
- Zigbee Manufacturer: _TZ3210_ncw88jfq
- Communication Protocol: ZigBee 3.0
- Temperature Range: -10°C~60°C
- Temperature Accuracy: ±0.2°C/±0.4°F
- Humidity Range: 0%—99%RH
- Humidity Accuracy: ±2%RH
- Working Voltage: DC3V
- Battery: 2xAAA
- Dimensions: 51x51x16.5mm
- Reporting Interval: 30min
This device ships in a small tiny box containing nothing but the device and a sticker for mounting. There was no user manual, everything is printed on the back of the box.
The screen seems great, the contents are properly spaced and padded. The viewing angles are also very good, better than most devices I’ve tested so far. Overall, the device feels very compact and gives off a high quality vibe.
The device is powered by 2xAAAs, inserted under the back cap. The button reachable with a hairpin via the small hole is used to put the device in pairing mode or reset it.
Prying open the sensor was very easy, being careful not to damage anything since it’s so small. The main PCB is very neat and tidy, no excess solder or dirt scattered around.
The actual temperature and humidity sensor is model AHT20 [Datasheet] by a company called Aosong Electronic from Guangzhou, China. This sensor is also found in one of my favorite climate sensors with a screen. Adafruit sells a rebrand of this sensor too.
Zigbee communication is handled by a Telink TLSR8258 [Datasheet], which is a BLE + Zigbee IEEE802.15.4 multi-standard wireless SoC. Remains to be seen whether or it communicates well with Z2M/ZHA.
Home Assistant Integration
This Tuya Zigbee Climate Sensor model LKTMZL02-ZX is supported in Zigbee2MQTT and ZHA out of the box, no external converter/quirk is needed. To pair it, you need to use a hairpin and push the button inside until the LED starts blinking red.
Once paired, the device is identified as an EndDevice labelled model TS0201 by Zigbee manufacturer _TZ2310_ncw88jfq. It exposes the following entities in Home Assistant through Zigbee2MQTT:
The calibration menu of Zigbee2MQTT is also functional, you can set the precision of the measurements reported as well as offset the values if they are inaccurate.
This model is also supported in ZHA out of the box, which I might add is rare for these types of devices. It’s also identified correctly as an EndDevice model TS0201 by manufacturer _TZ2310_ncw88jfq.
No additional development or tweaking is needed, the sensor reports it’s measurements perfectly fine out of the box.
Like the other climate sensors I’ve tested, I compare the measurements against a calibrated Xiaomi LYWSD02 BLE temperature and humidity sensor. Data was accumulated over 7 days and graphed with the History Explorer Card in Home Assistant.
The reporting interval coded in this sensor is fairly common in these types of Zigbee devices, to preserve battery and extend it’s life. It operates in the following manner from my tests:
- Report every 30 minutes regardless of state change
- Report immediately when there is a significant temperature change (≥1°C) from it’s last payload
This sensor was very accurate in reporting my living room temperature. Compared to the LYWSD02, it mirrored the graph spanning 2 days with an average offset of 0.5%. Calibration was not needed, although possible through Zigbee2MQTT or a simple template sensor.
The humidity reported was offset by a factor of 10. This means the value reported is 10 times lower than my LYWSD02 sensor. This is a mistake in the external converted used in Zigbee2MQTT, so to get an accurate reading reported in Home Assistant I need to either edit the convertor or calibrate the device.
After calibration, I noticed the actual humidity measurement was reasonably accurate and mirrored the graph of my LYWSD02 sensor with an average offset of 3%. It’s worth noting the values on the actual screen of the device are correct.
Pricing and Availability
You can purchase this device on AliExpress for around $10. On Amazon, only the Wi-Fi version is available, which is compatible with the Tuya Ecosystem and the Smart Life app; the Zigbee version is not listed.
If you get it from one of the links bellow (affiliate), you are directly supporting smarthomescene.com in the form of sales commission, so I can continue to get obscure devices and test them out.
This Tuya Zigbee Climate Sensor model ZL02-ZX is a cheap Zigbee temperature and humidity sensor with a display. It has no extras like clocks or alarms but does it’s primary function perfectly fine.
The LCD screen pleasantly surprised me, it’s quality and viewing angles are great, if not the best of all the sensors with a screen I’ve tested so far. However, it’s worth noting the screen is pretty small, so don’t hope you will actually see the information shown from way across the room.
Build quality is also very good, the sensor feels compact and premium when handled. The 2xAAA batteries are also a point in favor, since they are very common and easily replaceable. Battery life will also be better than most, taking into account the reporting interval and small screen.
Reporting interval is preset to 30 minutes by default, you cannot make the device report faster. However, It will push it’s payload sooner if there is a significant climate change (≥1°C).
All things considered, I can comfortably recommend this model for anyone looking for a small, cute, yet capable temperature and humidity sensor. Before you buy, I would also suggest you read the other reviews as well, especially the SZ-T04 or if you are looking for a larger screen, the JM-TRH-ZGB-V1.