When the problem didn’t go away I realized something was wrong with the water in my apartment.
There was low pressure, and the boiler was giving almost no hot water.
I contacted plumbers, but everyone gave different explanations — filters.
I began reading technical materials. 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.
It’s a useful site for home issues to anyone who wants to avoid unnecessary repairs.