I'm having problems with some of my radiators.
Some of them get red hot, but others get barely lukewarm. They're warmer at the top than the bottom so I drained it down and put some sentinel x800 in it thinking it was probably sludge.
One of the radiators that wasn't working started to get hotter but the other it wasn't making much difference for so I left it in, it's now been in a week and a half but the radiator that was starting to get hot is now not heating up again.
What could it be?
Should I give up and drain it out or leave it in longer?
