Over a period of time the water contained in your heating system will no doubt have lost its Inhibitor and will be generating a build up of sludge and corroding the internal surfaces of radiators and boiler components, This could be due to any number of reasons but usually the system has at some time been drained for a repair or alteration and refilled without the addition of a suitable inhibitor.
This inhibitor is vital to the modern day combi boiler as the internal waterways are so small that any build up of sludge or scale will reduce the efficiency and in severe cases cause the boiler to cut out on hot water demand.
A powerflushing pump forces high velocity water with the addition of a suitable cleanser through the whole of the system, This include every radiator, all of the pipework and all the internal waterways of the boiler. The system is then flushed with clean water and finally a suitable inhibitor is introduced.
In severe cases of a combi boiler cutting out on hot water demand, the internal plate heat exchanger may need removing from the boiler and cleaning and flushing remotely.