The Fernox Leak Sealer F4 - 500ml is used throughout domestic heating systems for sealing small, internal, inaccessible leaks. This sealer reduces the pressure loss from sealed systems and works best in warm/hot circulating water and once evenly dispersed will usually be effective within 1 - 24 hours. The sealing efficiency of Leak Sealer F4 has been intentionally limited to prevent blockage of safety devices, pumps, etc. This product is compatible with all metals and materials commonly used in central heating systems.
Reduces pressure loss from sealed systems
Seals most small inaccessible leaks
No need to drain & repair
No blockage of pumps or vents