Cleaner F3 is an effective, universal pH neutral, non-foaming liquid cleaner, which removes sludge, scale and debris from existing central heating systems to restore heating efficiency and eliminate boiler noise. When commissioning new systems in accordance with BS 7593:2019 regulations and best practice, Cleaner F3 is ideal to remove flux residues and other installation debris to help extend the life of the boiler and the efficiency of the system. It is suitable for use when powerflushing to accelerate the cleaning process in existing and contaminated systems. Cleaner F3 is a non-hazardous product which is compatible with all metals commonly used in heating systems, including aluminium.
A single dose of Cleaner F3 treats a larger sized property with a heating system of 130 litres, up to 16 radiators, or 250 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 500 ml 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): 6.4
pH (in-use) 6.5 – 7.7
SG: 1.145 @ 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)
182 × 88 × 52 mm
195 x 268 x 182 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.