Fernox Cleaner F3 265ml is a universal, fast acting and effective pH neutral cleaner for central heating systems. It is designed to remove debris, sludge and scale from existing systems. It restores heating efficiency and eliminates boiler noise. Designed for pre-commission cleaning of new installations in accordance with BS 7593:2019, by removing flux residues and other debris to help extend the life of a system.
Part of the tried and tested Fernox Cleaner range, this 265ml product offers reduced packaging and waste without compromising on high performance, quality and ease of use. This conveniently size bottle can treat an average 100 litre system or 12 radiators and maybe dosed via a TF1 Filter.
Cleaner F3 can be used for all types of cleaning methods; manual or magnetic flushes and for heavily sludged systems, Cleaner F3 can be used in conjunction with a powerflushing unit.
Cleaning a central heating system using Fernox Cleaner F3 and protect with Fernox Protector F1 can restore and maintain system efficiency resulting in a gas saving of up to 15% every time you heat your room.
A single dose of Fernox Cleaner F3 265ml is sufficient to clean an average domestic heating system of 100 litres, up to 12 radiators, or 190 sqm of underfloor heating. Additional / repeat applications of Cleaner F3 may be necessary for larger systems, or if systems are heavily sludged. Alternatively, Power Cleaner F8 may be used for heavily sludged systems.
First drain and refill the entire system with plain water. For optimum results the entire system, including drop feed radiators where fitted, should be completely drainable. Preferably, full bore gate valves with hose connectors should be provided temporarily for this purpose. Motorised and thermostatically controlled valves must be set so that no part of the system is closed off during cleansing, or rinsing. Discharges must be made to the foul drain and not the surface water drain. For open vented systems add Cleaner F3 via the header tank. For sealed systems add via a suitable dosing point, or use Fernox Cleaner F3 Express 400ml.
Fernox Cleaner F3 can also be used in conjunction with a powerflushing unit. In this case, please refer to the unit manufacturer’s instructions. When pre-commission cleansing new systems, Fernox Cleaner F3 should be circulated for a minimum of one hour at normal operating temperature. For cleaning existing systems, sludge and debris should be dispersed also within one hour at normal operating temperatures. However, to remove hardened iron oxides and limescale, the cleaning time can be extended to up to one week under the normal heating cycle. If a radiator still has a cold spot after one hour, increase the flow through the radiator by closing the valves on the other radiators.
An additional or repeat dose of Cleaner F3 may be necessary in some cases. Drain and flush thoroughly, at least twice, until the water runs clear. When using Cleaner F3 with a powerflushing machine, cleaning should be completed within an hour. Use dynamic flushing with plain water until the water is clear. Refill the system adding Fernox Protector F1 for long term protection against corrosion and limescale. In single feed indirect cylinders, e.g. “Primatic” or similar, potable water chemicals must be used.
“Cleaning a central heating system using Fernox F3 Cleaner and protecting with Fernox F1 Protector can restore and maintain system efficiency, resulting in a gas saving of up to 15% every time you heat your room. This saving is equivalent to 110 Kg CO2e per typical home per year.”*
Fernox Cleaner F3 is supplied in 265ml bottles.
Fernox Cleaner F3 is classified as non-hazardous for human health, but as with all chemicals, keep out of reach of children. In case of contact with eyes or skin, rinse immediately with plenty of water.
Odour: Faintly aromatic
pH (conc): 6.7
pH (in-use) 6.5 – 7.7
SG: 1.195 @ 20°C
Single Unit Dimensions(Height x Width x Depth)
Single Unit Barcode
Outer Carton Dimensions(Height x Width x Depth)
Outer Carton Barcode (ITF)
148 × 60 × 47 mm
241 x 178 x 127 mm
Fernox Cleaner F3 should ideally circulate around the system for at least one hour, or up to a week, after which it should be drained out and the system flushed/ cleaned before adding Fernox Protector F1 or Protector + Filter Fluid together with a Fernox TF1 Filter to protect the system from further corrosion and scale formation.