One of the radiators on my combi boiler central heating system is cold at the middle bottom. I have drained it and the water inside was very black. I have put Sentinel X400 in the system and after 2 days it’s still not improved. And still cold in the same place.
What other option can I try? I can not afford a power flush at the moment. Any suggestion would be much appreciated.
What other option can I try? I can not afford a power flush at the moment. Any suggestion would be much appreciated.