I installed this valve three years ago on a radiator in the living room, but it never worked until about a week ago.
As you can see in the photos, the nut of the stem broke, and I assume it was due to expansion and contraction because it was never forced, hit, or anything else.
The edge of the nut, as you can see, is very thin, it has no substance.
Fortunately, I noticed that there was a leak and it was running vertically down the pipe, with the water ending up in the hole in the tile.
Luckily, I saw it in time and we didn't have to tear up the floors.
Unacceptable product, and unfortunately, I installed it on the other 9 radiators in the house and they cost quite a bit of money.
It's a shame because it's a Greek company.
