Yes, all Fernox internal leak sealers, such as Fernox Leak Sealer F4, are safe for use with combination and other low water content boilers.
They will not block valves or vents. Leak Sealer F4 Express is recommended for all pressurised systems as this can be added in 30 seconds via a radiator, filling loop or Fernox TF1 Filter, without the need to drain the system.
Power Cleaner is phosphate, nitrate and nitrate-free and is developed to exceed all regulatory and legislative guidelines in regard to the environment impact of the formulation. It is compatible for use in mixed metal heating systems, including aluminium.
Power Cleaner F8 is a concentrated formulation supplied in 500ml bottles, to reduce packaging waste. Just one bottle treats larger systems of 130 litres, 16 radiators or 250 sqm of underfloor systems and one dose is sufficient for cleaning the central heating systems of up to 97% of all UK homes (or larger heating systems).
Soft and hard limescale on radiator walls can drastically reduce their ability to heat rooms efficiently. The problem often revolves around the boiler heat exchanger where the temperature is hottest, but deposits in radiators and pipework also lessen the effectiveness of the whole system. It is therefore important to consider the whole central heating system when checking and establishing why
