Formerly LEAKEX by Purimachos EVERBUILD P13 LEAK SEALER is an internal leak sealer which when applied to a system can help to avoid costly repairs. P13 LEAK SEALER can be used for small leaks & weeping joints in most central heating systems. * Will not block pumps or air vents. * Compatible with all EVERBUILD central heating products. * Forms a soft seal within 24 hours of entering the primary circuit. * New & existing central heating systems. * Extensions to existing systems.