Hello everyone,
We have two heating circuit manifolds in the house, one in the basement and one in the attic. The flow meters in the basement are all clear and easy to read. In the attic, they are completely discolored.
Why is that? Can it be fixed? Does it have negative effects on the heating circuits in the attic?

We have two heating circuit manifolds in the house, one in the basement and one in the attic. The flow meters in the basement are all clear and easy to read. In the attic, they are completely discolored.
Why is that? Can it be fixed? Does it have negative effects on the heating circuits in the attic?