Fernox F3 Cleaner Liquid 500ml
Fernox F3 Cleaner Liquid 500ml is a professional-grade, pH-neutral system cleaner designed to remove sludge, limescale, flux residues and installation debris from central heating and water underfloor heating systems. Suitable for both new and existing installations, it helps restore circulation, improve heating efficiency and prolong the life of boilers, pumps and system components.
Whether you’re commissioning a brand-new heating system or restoring an older installation affected by magnetite sludge, Fernox F3 provides fast and effective cleaning without damaging system materials. Its non-foaming, non-hazardous formulation is compatible with all common heating metals, including aluminium, making it one of the industry’s most trusted cleaning chemicals.
Why Choose Fernox F3 Cleaner?
A clean heating system works more efficiently, heats faster and places less strain on expensive components such as boilers and circulation pumps.
Removes Sludge and Debris
Effectively disperses magnetite sludge, installation debris and accumulated contaminants that restrict water flow.
Restores Heating Efficiency
Cleaning the system helps radiators and underfloor heating circuits deliver heat more efficiently while improving circulation.
Ideal for New Installations
Removes flux residues and installation debris during commissioning in line with BS 7593:2019 best practice.
Safe for Modern Heating Systems
Compatible with aluminium heat exchangers and all common metals used within central heating and underfloor heating systems.
Professional Installer Favourite
Trusted by heating engineers throughout the UK for routine system cleaning and powerflushing applications.
Key Features
- Genuine Fernox product
- 500ml bottle
- Removes sludge, limescale and debris
- Suitable for new and existing systems
- pH neutral formula
- Non-foaming
- Compatible with aluminium
- Suitable for powerflushing
- Easy to flush from the system
- Suitable for central heating and underfloor heating
Technical Specification
- Brand: Fernox
- Product: F3 Cleaner Liquid
- Size: 500ml
- Product Code: 56600
- Formula: pH Neutral
- Application: Heating system cleaner
- Compatible With: All common heating system metals including aluminium
- Suitable For: Central heating and water underfloor heating
- Treatment Capacity: Up to 130 litres of system water, approximately 16 radiators or 250m² of underfloor heating.
What Does Fernox F3 Cleaner Do?
Over time, heating systems naturally accumulate corrosion products, sludge, flux residues and scale deposits. These contaminants restrict water flow, create cold spots, increase boiler noise and reduce heating efficiency.
Fernox F3 Cleaner works by breaking down and suspending these deposits so they can be flushed safely from the system. Once the cleaning process is complete, the system should be refilled with clean water and protected using Fernox F1 Protector to help prevent future corrosion and scale formation.
Ideal Applications
Fernox F3 Cleaner is suitable for:
- Central heating systems
- Water underfloor heating systems
- New heating installations
- Existing heating systems
- Boiler replacements
- System commissioning
- Powerflushing
- Radiator cleaning
- Heat pump heating circuits
- Commercial heating systems
Benefits of Cleaning Your Heating System
Cleaning your heating system before adding inhibitor helps maximise efficiency and protects expensive heating components.
Benefits include:
- Removes sludge
- Eliminates installation debris
- Restores water circulation
- Improves radiator performance
- Increases underfloor heating efficiency
- Reduces boiler noise
- Helps extend boiler life
- Supports lower energy consumption
Fernox states that cleaning with F3 and then protecting the system with F1 can help maintain heating efficiency, with independently verified testing showing gas savings of up to 15% under suitable conditions.
Complete Your Heating System Protection
For maximum protection, combine Fernox F3 Cleaner with complementary products available from Kudos Trading.
Fernox F1 Protector
Protect your heating system against future corrosion and limescale once cleaning has been completed.
Magnetic System Filters
Capture circulating magnetite sludge before it reaches your boiler and pump.
Central Heating Pumps
Restore efficient circulation with our range of Grundfos, Wilo and Bastion heating pumps.
Underfloor Heating Manifolds
Maintain balanced flow across every heating zone.
Heatmiser Controls
Improve heating efficiency with accurate room-by-room temperature control.
Underfloor Heating Pipe
Complete new heating installations using premium PE-RT and multilayer pipe.
Why Buy Fernox F3 Cleaner from Kudos Trading?
With over 25 years of experience supplying heating professionals, plumbers and homeowners throughout the UK, Kudos Trading stocks genuine Fernox products at competitive prices.
When you buy from Kudos Trading, you’ll benefit from:
- Genuine Fernox chemicals
- Competitive prices
- Fast UK delivery
- Expert technical advice
- Large stock availability
- Friendly customer service
- Trusted heating specialists
Frequently Asked Questions
What is Fernox F3 Cleaner used for?
Fernox F3 Cleaner removes sludge, limescale, flux residues and debris from central heating and underfloor heating systems to improve efficiency and circulation.
Can Fernox F3 be used in underfloor heating systems?
Yes. One 500ml bottle treats systems up to approximately 250m² of water underfloor heating.
How much heating system does one bottle treat?
A single 500ml bottle treats up to 130 litres of system water, approximately 16 radiators or 250m² of underfloor heating.
Is Fernox F3 safe for aluminium boilers?
Yes. It is compatible with aluminium and other common heating system metals.
Can it be used with a powerflushing machine?
Yes. Fernox F3 is suitable for use during powerflushing to accelerate the cleaning process.
Should I add inhibitor afterwards?
Yes. Fernox recommends protecting the cleaned system with Fernox F1 Protector after flushing.
How long should Fernox F3 remain in the system?
For most systems it circulates for around one hour, although heavily contaminated systems may require longer treatment depending on the level of sludge.
Is Fernox F3 non-hazardous?
Yes. It is classified as a non-hazardous, pH-neutral cleaner when used as directed.
Why buy Fernox from Kudos Trading?
We supply genuine Fernox products backed by expert advice, competitive prices and fast nationwide delivery.
Related Products
- Fernox F1 Protector
- Fernox F8 Power Cleaner
- Fernox F7 Biocide
- Fernox DS40 System Cleaner
- Magnetic Boiler Filters
- Central Heating Pumps
- Underfloor Heating Manifolds
- Heatmiser Controls
- Underfloor Heating Pipe
Next Working Day Delivery: Yes, we hold all our products in stock at our 7000 sq ft Nottingham warehouse and at our 3000 sq ft warehouse in Market Harborough and use DPD for a tracked next-day delivery.
Collection Available: You can always collect from our Nottingham location and help yourself to a free tea and coffee.

