If sludge is allowed to build up, it can result in blocked pipes, inefficient radiators and damaged parts in the boiler. The heat exchanger in a boiler consists of many narrow pipes which the water passes through to heat up. If the narrow pipes become restricted or blocked, the boiler will shut down to prevent it from overheating and getting even more damaged. If the boiler breaks down because of sludge in the system, the repair work is not covered by the boiler warranty and could lead to expensive repair bills.
Sludge can cause: