First time ordering from an online store, I had some doubts if everything would go well…

Everything perfect!!

The Hager ESC225 is a "put it in the panel and forget it exists" level of reliability. Sturdy 25A rail relay/contact, 2NO, with 230V coil, in 1 module, ideal for automation, water heaters, lighting, loads, etc. The build quality is evident, it snaps nicely onto the rail and easily accepts cables (up to 10mm² rigid / 6mm² flexible), so installation is hassle-free.
For anyone who wants a serious component in the electrical panel instead of "whatever", it is a flawless choice.

It does make a magnetic noise but you have to put your ear right up to hear it. When you close the panel door, it is impossible to hear it. I had also tried the ESC240S which is completely silent, but it broke after 2 years. I believe this one will last more hours of operation. I've already had it for 1 year without problems. I will update when it breaks.

Connected to a WiFi sonoff switch to activate the water heater via WiFi. Very good quality.

I used it together with Shelly em to control the water heater from my mobile.

It makes incredible noise... Like having a DEI transformer inside the house... If you want it for home use, better get the ESC240S model, which is the silent model (currently it costs 2€ more but you can't hear it at all!).

Very good power relay, it does what you buy it for. Its downside is that there is no electrical operation indicator. There is a visual indicator but it is not an LED, so it is not distinguishable in a dark environment.