Fernox F4 Express Leak Sealer 265ml

• Seals small leaks fast: Designed to seal minor leaks and weeps in radiators, pipework, joints and inaccessible micro-leaks without draining the system.
• For most heating system types: Suitable for sealed and open-vented central heating systems; compatible with typical system metals and plastics.
• Non-blocking formulation: Formulated to minimise risk of blockages and maintain circulation when used as directed (does not replace mechanical repair for major leaks).
• Simple dosing and application: Add via radiator, dosing point, filling loop, or other suitable access point; ideal for emergency call-outs and ongoing weep issues.
• Professional maintenance support: Helps reduce pressure loss and repeated top-ups; can be used as part of a broader system treatment plan (e.g., cleaner/inhibitor regimen).

Fernox F4 Leak Sealer (500ml) is an internal central heating leak sealant formulated to help seal small leaks and weeps in radiators, pipework and joints, including hard-to-reach micro-leaks where a mechanical repair is not immediately practical. Suitable for sealed and open-vented systems, Fernox F4 is designed to work while the system is circulating, helping to reduce ongoing pressure loss and repeated top-ups. It is a practical option for both trade engineers and DIY homeowners dealing with minor leak issues. Key Benefits: Helps seal small internal leaks and weeps For radiators, pipework, joints and inaccessible micro-leaks Suitable for sealed and open-vented central heating systems Designed to minimise the risk of blockages when used correctly Can be added via a suitable access point (radiator/dosing point/filling loop) Important: Fernox F4 is intended for minor leaks and weeps. It is not a substitute for repairing significant leaks or failed components. Always follow the manufacturer’s instructions regarding dosage, circulation time, and system conditions.