Fernox F4 Express Central Heating Leak Sealer at Heating Spares is part of the Fernox central heating water treatment range from Fernox. The Fernox Leak Sealer F4 Express is used in domestic heating systems for sealing small inaccessible leaks.
The Fernox Leak Sealer F4 Express works best in warm/hot circulating water. Once dispersed evenly in the system water it is effective within 1 - 24 hours. The sealing efficiency of Fernox Leak Sealer F4 Express has been formulated to prevent blockage of safety devices, pumps, etc.
For long term protection against corrosion and limescale we recommend systems are cleaned using Fernox Cleaner F5 Express and inhibited with Fernox Protector F1 Express.