Everbuild Central Heating P11 System Cleanser Concentrate will remove commissioning and flux residues from new systems and restore circulation to old systems which suffer from sludge. Everbuild P11 System Cleanser should also be used when components are replaced or existing systems are extended. This product is compatible with plastic tanks, micro bore and all metals (including aluminium) used in central heating systems. It is very economical as 1 litre will treat a 100 litre system capacity in new and existing central heating systems or extensions to existing systems. Size 1 litre.