Leak Sealer F4 is a internal leak sealer developed for use throughout a central heating system to seal small, inaccessible leaks and weeps which may cause pressure loss and boiler breakdown. Once dispersed within the system, the product finds the area of oxygen ingress and forms a polymer to seal the pinhole. Effective within 1-24 hours after application, the unique sealing efficiency of this market-leading water treatment chemical has been proven to prevent blockages or restrictions within the boiler or vulnerable system components such as pumps and safety devices. A leak can be quickly and efficiently sealed, without the need for a complete system drain down.

Ideal for reducing pressure loss from sealed systems

Seeks out and seals inaccessible, internal microscopic leaks fast

Saves time and money on draining down and repairing

Safe to use – does not cause blockages in pipework or vulnerable boiler components such as pumps, air vents and heat exchangers

Left permanently in the system – compatible with all metals and materials, including aluminium

One 1 pint recyclable bottle treats up to 34 gallons of system water (16 radiators)