Tuya TRV (thermo radiator valve). Device breakdown.

Igor Mullin
3 min readOct 20, 2021

I’m not lucky with Tuya TRV (thermo radiator valve), the product was expected to be good, but in fact it brings only frustration so far. With the beginning of the heating season, I activated the thermal heads and only 3 out of 4 started.

This is a translation of my article in Zen. Also, do not forget to read us in other services: Instagram, telegram (RU, EN, DE). Medium, LiveJournal, YouTube(old channel), YouTube (new channel).

Let me remind you that of the 4 devices purchased, only 3 were working. One of them had to be returned immediately, but for some reason I contacted the support service and only lost time. The latest article dedicated to this regulator is here (RU).

In the summer, I put one device in a box, I don’t remember why, I probably wanted to solder it to external power and output the temperature sensor. Let me remind you that if the temperature sensor is left in the case, then the PID controller goes crazy and constantly regulates something, but even more — it gets on your nerves with noise in the night, discharging the batteries.

Taking the valve out of the drawer, I saw that the case had burst and the valve could no longer work on batteries. I made the modification described here and installed the valve in place. But it didn’t work anymore. Maybe I damaged it during soldering, maybe because of the DC-DC converter, or maybe something third. Obviously, the valve will now go for modification, which I will write about later. But here’s what’s interesting, leaving the valve on — I saw that sometimes it turns on and works. I tried to figure out the addiction, but without success. Leaving the valve on, I saw that it was working, but 100 times slower than usual. I made a video that is divided into 2 parts of 8 minutes each. at 4.37, the inscription U1 appears. In normal mode, this is 3 seconds.

But in 8 minutes the inscription U1 did not go out. But as soon as I pressed the record of the second piece, the “house” lighted up. Until 1.55, the house is lit brightly and the date and time setting symbols are lit. By the way, you can pay attention that the LEDs are updated at a visible rate. It feels like the controller has switched to work at a reduced speed, and we see every operation.

At 1.54, I press the house key and enter the time setting menu and that’s what’s strange, there are no brakes in this menu and the time setting passes quickly, as if there were no problems before. Naturally, calibration will not work, because the motor is not connected to the board.

I connect the motor and as you can see, the restart goes a little faster, but not so much to be happy about it. Having started the calibration with the motor, we are surprised that it works.

But it’s too early to celebrate. The motor made one forward and one backward movement. Then the cycle should repeat, but error e1 appears. Apparently, the part responsible for the motor is also damaged in the firmware. I conducted the experiment again, but it did not give me any results. Video below.

In our next articles, we will disassemble the thermostat and analyze its circuitry, see what can be done.

And that’s it, we comment, subscribe, like, repost … this will help articles to come out more often.



Igor Mullin

I´m a Hardware and Software Engineer and a PhD. In my professional activity I focus on such things like smart home systems and electric development.