Leak Sealer F4 Express 13 fl oz (400ml)

Product Code: 62438

Leak Sealer F4 is a internal leak sealer developed for use throughout a central heating system to seal small, inaccessible leaks and weeps which may cause pressure loss and boiler breakdown. Once dispersed within the system, the product finds the area of oxygen ingress and forms a polymer to seal the pinhole. Effective within 1-24 hours after application, the unique sealing efficiency of this market-leading water treatment chemical has been proven to prevent blockages or restrictions within the boiler or vulnerable system components such as pumps and safety devices. A leak can be quickly and efficiently sealed, without the need for a complete system drain down. The Fernox Express range uses Barrier Pressure Pack technology and compressed air propellent to expel the product so the entire range is non-flammable. The propellent (compressed air) is not mixed with the active product so there is no risk of air ingress into the system which could accelerate future risk of corrosion.

  • Seeks out and seals inaccessible, internal microscopic leaks fast
  • Quick and convenient – doses in 30 seconds – no need to drain down the system
  • Safe to use – does not cause blockages in pipework or vulnerable boiler components such as pumps, air vents and heat exchangers
  • Non-toxic, environmentally friendly formulation, compressed air propellant and 100% recyclable can
  • Saves time and money on draining down and repairing.
  • Add via a radiator, filling loop or TF1 System Filter – all adapters supplied
Application, Fitting & Dosing

A single dose of Leak Sealer F4 Express treats a larger sized property with a heating system of 34 gallons, up to 16 radiators or 250 sqm of underfloor heating and can be dispensed directly into a radiator air vent, system filling loop, or via a TF1 Filter using the appropriate adapter supplied with the product. Fernox Express takes less then 30 seconds to dose the system without the need to drain down the system, saving time on-site. If dosing via a TF1 Filter, the filter should be emptied of any collected contaminants prior to treating with the product. In single feed indirect cylinder, e.g. ‘Primatic’ or similar, potable water chemicals must be used.

Physical Specification / Properties

Colour: White
Form: Viscous liquid
Odour: Faint
pH: 5.0 – 7.0
SG: 1.0 @ 20°C

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