Hot water from vent: Why?

Good evening!

Today I wanted to replace a kitchen faucet, but I was unsuccessful. Since the local angle valves are no longer functional, I turned off the main valve. To prevent too much water from flowing into the kitchen, I opened the lowest valves, that is at the sink in the basement, to drain the system. Since I was unable to get the locking ring of the faucet over the four supply and drain hoses, I reassembled everything and turned the water back on.

Since then, hot water flows permanently from the vent at the highest point of the system, and from there into the funnel. So nothing goes wrong, but I wonder why water is flowing all the time. This never happened before. Does anyone have an idea? I can't reach my plumber...

Matthias

There is dirt in the [entlüfter] or the float is sticking. It could also be lime scale. Try tapping on it. In the worst case, it must be replaced or disconnected. Nowadays, people don’t do that anymore anyway.

Knocking doesn't help. I am still waiting for my installer’s feedback. I don’t even know why it’s there in the first place. And why don’t people do that anymore nowadays? Replacing will definitely mean chipping off tiles...

Matthias

Knocking is pointless. I am still waiting for feedback from my installer.

Well, with that one I wouldn’t knock, but ring or call.

I did knock on the air vent, and I called the installer...

Then show a picture. Usually, you can unscrew them. These things were used on old fittings that did not have built-in backflow preventers so that in case of a leak, no dirty water flows back into the pipe.