Power flushing is a technique used to clear out sludge from central heating system pipes, radiators, coils and heat exchangers. These are areas where scale and corrosion can collect; the symptoms are usually: Cold spots on radiators, even after bleeding.
Dirty black or brown water present when bleeding radiators confirms system corrosion.
Radiators cold at bottom due to black sludge.
Radiators cold all over due to blocked valves and pipes.
Irritating boiler noise from sludge or lime scale build up, a warning sign of imminent costly problems.
Little or no hot water due to blocked pipes and heat exchangers.
Boiler cutting out and no circulation due to blocked pump.
Radiators cold at top and need bleeding due to gases, a by product of rusting.