I just troubleshooted a bit more and found that the balance valve was sticky. Turned right, and left few times and the humming noise seemed to be cured. The picture is attached.
I wanted to reach out regarding a peculiar issue I've been experiencing with my heating system, and I'm seeking your expertise for guidance.
I have a combi-boiler located downstairs, with the tank and motorized valves situated upstairs, specifically two zones and hot wanter. Recently, I've...