The need for power flushing comes from a build-up of oxide sludge and calcium in the central heating system. Sludge or calcium build up in a heating system means there could be an underlining problem that’s allowing air to get into the central heating system, causing radiators and heat exchangers to corrode. This leaves rust and debris in the bottom of radiators which corrodes down into oxide sludge. This then leads to blocked waterways in radiators, pipe work and heat exchangers.&n...