Eventually I realized something was wrong with the water in my apartment.
There was pressure fluctuations, and the boiler was giving almost no hot water.
I contacted repair services, but everyone gave different explanations — old system.
I searched for clear information. That's how I found this website:
https://stroyka2001.kh.ua There they clearly explain causes of low pressure.
After reading a few articles, I understood why previous repairs didn't help.
Now I recommend this website to anyone who wants to figure out water problems.
