Worcester Greenstar System Filter is designed to stop dirt and debris in the water from reaching the boiler. It protects the entire central heating system from rust and solder fragments and reduces build up of black sludge within radiators and central heating systems. It has red and green indicator lights to show when it’s in operation with the isolation valves being activated using a single 90deg turn. The filter is engineered to allow for bi-directional flow and improves efficiency levels.