---Fast-acting formula: The Fernox F3 Cleaner Express 400ml boasts a quick and efficient cleaning formula. It is designed to remove sludge, flux residues, and other debris from heating systems in just one hour. This allows for minimal disruption to the homeowner and quick completion of maintenance tasks. ---Convenient dosage: The product comes in a 400ml canister, which is sufficient to treat an average central heating system of up to 130 liters, 16 radiators, or underfloor systems up to 250m2. This makes it a cost-effective solution for both small and large-scale heating systems. ---Powerful degreasing properties: The F3 Cleaner is renowned for its impressive degreasing ability. It works to remove grease and oil from the system, thus improving its efficiency and lifespan.