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13 Posted 6 March 2023
Fernox F4 Express Leak Sealer 400ML - £12.99 + Free click and collect @ Screwfix
About this deal
For use in domestic heating systems for sealing small inaccessible leaks. Quick and convenient, doses in only 30 seconds. Works best in warm / hot circulating water. Once dispersed evenly in the system water it is effective within 1-24 hours. The sealing efficiency has been formulated to prevent blockage of safety devices, pumps, air vents and more. Compatible with all Fernox Protectors.
1 Year Guarantee
Non-Toxic, Environmentally Friendly Formulation
100% Recyclable Can
Compatible with All Fernox Protectors
More details at Screwfix
Community Updates
Edited by a community support team member, 6 March 2023
13 Comments
sorted byTopped up my pressure about 2 weeks ago to 1.2bar and today it's again at 0.9bar
I've checked all my rads on the circuit but cannot pin point the issue
I'm wondering if this could repair it
A lot of my piping is under floors or chased into walls (edited)
Note - if you've been needing to regularly top up your boiler pressure over winter then you will need to make sure you've put some more inhibitor back in as it will have diluted somewhat.