Hi, I had or I have, because I don't know if it was solved. We have 30 years ago, a small building, which basically has a 7m high tank, a single 32mm downpipe in threaded PPN and feeds 5 apartments all on the ground floor (I will try to send a scheme) are 5 units, all on the ground floor, forming a strip, with its aisle on one side. The 32mm PPN drop goes through all the apartments above the ceiling and in each one, it has a tee for cold water and another for hot water, that is to the hot water tank, all with their stopcocks, relief valve. So it always worked without problems, beyond thermos changes, etc.- Yesterday several people call me saying that the descent made noise, I went to see and as such towards an incredible patter, like water hammering one after another, close a key step down and stopped. Within an hour or a little more, the thermos of apartment 2 broke the cold water hose and a stream of water and steam began to flow at very high pressure. We close the gas, let it depressurize and leave it to check the control, which seems to not close. three hours later, the neighbor of the 1 called, that his hot water tank loses through the connections and high pressure steam comes out x the faucets. We turn it off and depressurize too. The thing is already very rare. The next day we see that the loss loses by several threads of 30 years, we review both thermoses, we solve losses of descent and thermos connections, we fix flexible broken, we turn both and both turn on and off normally. So I remain. What could happen? evidently it is very strange that they simultaneously fail and do not cut the regulator, to inject steam under pressure in the descent without water (I remember that we close it x the ram) I never saw this, that the water tanks produce those events in a building. What do you think???