ᐅ Discoloration of Heating Water (Only the Supply Line)

Hello everyone, I noticed that the supply line on the underfloor heating manifold has developed discoloration.



I’ve read about various causes, from harmless biofilm to rust or sludge buildup.

What seems strange to me is that only the supply line is discolored, while the corresponding return line is not. The heating water should have been mixed during the screed’s heating process, right?

Has anyone experienced this before or knows what it might be?

It looks kind of odd, the Taccos still seem to be clear. Since when has the underfloor heating been running?

There is nothing unusual about it. It was simply built according to the principle: "This is how we always do it."

Let me guess, you have a MAG made of standard steel, and the heating water was either not demineralized at all or only insufficiently. Well, and possibly some other minor details.

But why are the Tacos and the return flow then clear?

Because the water is not yet saturated. After a heating period, everything will turn brown. There is simply not enough dirt in it yet, but due to ongoing chemical processes and heat acting as a catalyst, it will definitely happen. It’s not as if this is something new.

The system has been running since early January.