Last week I fixed a radiator that wasn't getting hot. Problem was a 2m microbore tube packed full of silt. After fixing I also fitted a Fernox Omega TF1, and cleaner solution for one week. I flushed it out today and there wasn't much sludge, it was pretty clean. Now I'm trying to make all three of the ground floor radiators get hot along the bottom edge. The combi is on the 1st floor. The radiators on the 1st and 2nd floor seem to get equally hot on the top edge as they do on the bottom edge. On the ground floor the radiators are bigger, and I can't get them as hot along the bottom edge. The two that I can lift myself (1000mm x 600mm) I've had outside today, with a hose blasting water through and hitting them with a rubber mallet. There was a little bit of sludge but not much. The water seemed to be coming through strong. It's more noticeable on the 2000mm x 600mm but the middle lower part only gets warm, whereas the top edge gets piping hot. Am I expecting too much, or may I have incredibly persistent sludge? ...side question; a 2000mm x 300mm rad is £95. The x 600mm version is £440. Why is it such a hike up?