As other users have mentioned, it is not a power relay and it should have included a power relay in the package. Mine burned out the first time I turned on the water heater. The 16A model together with a power relay costs about €50. For me, that's a fine price. I wonder why the 20A model exists since it is not a power relay (I had installed this one and it burned out). Easy pairing. Fully customizable. I highly recommend it with a power relay. 3 stars because if you don't know about the power relay, it will just burn out immediately!

Perfect! For the use I wanted, to turn on the water heater outside the house for a specific time or with a schedule, for example at night on low, it works just fine.

Respectable, I installed it to control the water heater.
It is good to have an electrician install it for obvious reasons.

Because I saw it in comments. Keep in mind not to expect, with any such Relay (controller) that is 16A to lift a device like the water heater. It will burn.
You also need a 25A power relay so that the geyer simply gives the command and the power relay "lifts" the load of the water heater!
So an additional cost of ~15€ is calculated.

Now I gave it 4 stars for glitches that the application may have. Generally, I have not faced any issues when the network goes down, etc.!

In my opinion, it is better than making a makeshift solution with an intermediate switch like sonoff, for example, because you have them integrated into your panel.
Now if someone wants something more high-quality, they go for shelly, but with double+ the cost!

I give 2 stars because while my wifi drops due to the repeater issue, when it comes back, it needs to be set up again from the beginning, which makes the product useless. I don't know if others have this problem, but I can't figure it out, and every time I lose internet, I can't understand why it doesn't reconnect. I will change the repeater that causes the problem at the end of the week, and if it works correctly then, I will change my review.

Edit: I changed the repeater, and now it works correctly, so it's not the device that was dropping from the network

Very good!
Also, for scenario issues, there is an option in the "smart" section to create some scenarios, for example, to set it to turn off after a certain period of time on its own.

Good relay that controls the power relay of the water heater at the moment. It requires some attention in connecting its sockets (it has a diagram on the side). It works perfectly with wifi without disconnections. For anyone interested, when it is connected to wifi, the green light is on (it illuminates the space like a night light). I give it 3 stars in the evaluation for the following reason: I wanted it to turn off after 20 minutes when someone presses the button and activates it. While the application supports such a scene, it turns off the control voltage whenever it feels like it (set at 20 minutes, it turned off at 3 minutes once and at 5 minutes another time). At least the countdown works correctly. These were tested with the geyer application, but also with the tuya application.

I bought this specific relay to control the water heater outside the house and through Google Home. I also needed an extra 20A relay to connect it to my own water heater. The installation needs to be done by an electrician.
It connects immediately without any problems. The only issue I had was with the Geyer application, it didn't show me the option to connect it to the Google system.
So, I downloaded the smart life application and it's much better! I connected it with the option to add an intermediate Wi-Fi switch. It has the option to set a timer, meaning it automatically turns off after a certain amount of time when you open it. There is also a button that, when pressed, turns it on and if you have set a timer, it turns off by itself.

I bought two for Mani and Rethymno.
Price and quality are perfect.
The automations you can create cover all needs.
The most important thing is that customer support is always available and incredibly good.

I use the Wifi relay to control the water heater (ON/OFF and based on time), from anywhere I am, as long as I am connected to the Internet. It easily connects to the home's Wifi router, through the user-friendly application. For the proper operation of the water heater, the wiring of an additional compatible relay and an ON/OFF switch is required, in order to ensure the functioning of the water heater in case the router, Internet connection, or Wifi relay fail.

The truth is that I didn't expect it to be so good! It connected to the wifi seamlessly and responded immediately to the functions. The app is also excellent, as it connects to Google Home. Keep in mind that in order to connect it to a water heater, you will need a power relay. I highly recommend it