Fernox F4 Express Leak Sealer F4 is used throughout domestic heating systems for sealing small inaccessible leaks. Quick and convenient solution which works in just 30 seconds - simple to use without any mess. Protects against corrosion and limescale, and can protects up to 10 radiators. Maintains system efficiency and extends boiler life.
Quick and convenient – doses in 30 seconds
Simple to use with no mess
Added via a radiator adapter or filling loop supplied
Saves time and money on draining down and repairing