Fernox - Leak Sealer F4 is suitable to seal small leaks and weeps which may cause pressure loss and boiler breakdown.
 
Once dispersed within the system it will be effective 1-24 hours after application. The unique sealing efficiency of this proven product has been specifically developed to prevent blockages or restrictions within the boiler or vulnerable system components such as pumps and safety devices.
 
 Ideal for reducing pressure loss from sealed systems
Seals most weeps and small inaccessible leaks
Saves time and money on draining down and repairing
Does not cause blockages of pump, air vents etc
Compatible with all metals and materials commonly used in central heating systems