Search in site


Are all Fernox Protectors suitable for use with Aluminum?

Yes, all Fernox Protectors ( ‘F’range and MB-1) are formulated for use with all metals Including Aluminum, stainless steel, cast iron and materials commonly used in central heating systems such as plastic pipe work . Simply treat as instructed.

Back to top

How much Fernox do I need?

One bottle, Superconcentrate cartridge, or aerosol is designed to treat a 100 liter system (up to 10 single radiators). The rule of thumb is to use the entire product to dose correctly. There is no detrimental affect from overdosing the system but under dosing can result in reduced protection.

Back to top

Where can I get Fernox products from?

Fernox is readily available form all good plumbers merchants, DIY stores and Building suppliers.

Back to top

Can you supply direct?

Fernox is a manufacturer of water treatment products which uses the merchant chain to supply and distribute its full range of products.

Back to top

What is the difference between Fernox F1 and MB-1?

Both of these products are inhibitors which protect the central heating system from the damaging effects of corrosion and lime scale. It is personal choice as to which product is suitable for the installer to use.

Back to top

How do I work out the system volume of my system?

Averagely, Fernox recommends its water treatment products are dosed one part to 100 liters of system water, which equates to 10 single radiators. Calculate the number of radiators and dose using the appropriate number of products i.e. 20 single radiators requires two bottles of 500ml product; two canisters of Superconcentrate ; two Express aerosols or two 4 liter bottles of MB-1.

Please refer to the instructions on the individual products. In the case of any uncertainty, please call our technical help line +44 (0) 870 8700362.

Back to top

Your number is on my boiler, can you fix it?

Fernox is a manufacturer of water treatment products only. Any problems with your boiler should be immediately referred to the boiler manufacturer or your maintenance service provider.

Back to top

Is Fernox Leak Sealer F4 compatible with Fernox Protector F1?

All Fernox products are formulated to be compatible for use in combination with each other. As with all chemicals, care should be taken if using in conjunction with another preparation/ chemical.

Back to top

Can Fernox Leak Sealer F4 work with plastic pipes?

Yes, Fernox Leak Sealer F4 is effective with metal and plastic pipe work.

Back to top

Can Fernox Leak Sealer F4 be used with Condensing boilers?

Yes, Fernox Leak Sealer F4 is safe and effective to use with all makes of Condensing boilers. The product is a proven and safe way to seal small leaks and weeps from a central heating system.

Back to top

Why do I need a powerflush?

Powerflushing is the fast and efficient way to remove sludge and debris from new and existing systems in order to restore or maintain the energy efficiency of your central heating system. The procedure/ time taken to powerflush varies depending on the size and condition of the system. It is recommended to powerflush before installing a new boiler to protect and extend the system’s life and maintain the boiler’s Sedbuk energy efficiency rating.

Back to top

Can I use a Fernox Boiler Buddy or Fernox Total Filter TF1 on 28mm pipe?

Both of these Filters provide additional protection to the system. The Boiler Buddy is an inline magnetic filter which offers a ‘window into the system’ for householders to check the water quality easily between annual servicing. It is designed for 22mm pipe work.

The Fernox Total Filter TF1 is an opaque, unique dual action hydrocyclonic and magnetic filter which is available to fit 22 mm and 28 mm pipe work.

Back to top

Does the Fernox Boiler Buddy and Fernox Total Filter TF1 need to be installed vertically or horizontally?

Both Fernox filters are capable of being fitted either vertically or horizontally and all fittings for either configuration are supplied with the products.

Back to top

Does the Fernox Quantomat need to be installed vertically or horizontally?

The Fernox Quantomat can be installed either way: vertically or horizontally.

Back to top

Can LS-X be used on plastic pipe?

Fernox LS-X is a proven external leak sealer and jointing compound that works quickly and effectively on all metal and plastic pipe work.

Back to top

Can I use LSX for sealing sink wastes?

Yes, Fernox LS-X is ideal for this application.

Back to top

Can I use LS-X around shower trays?

Yes, LS-X is ideal for this application.

Back to top

Is 99c Lead free solder suitable for use on solar heating systems?

Yes, but only where max temp will not exceed 227 deg C.

Back to top

Can I use Powerflow flux with leaded solder?

Yes, there are no compatibility problems with using these Fernox products in combination.

Back to top

What is the difference between Cleaner F3 and Powerflushing Cleaner F5? (formerly named Heavy Duty Restorer)?

Cleaner F3 is formulated for use with new and existing systems. Powerflushing Cleaner F5 has been developed for use with heavily sludged or contaminated systems and is ideal for powerflushing.

Back to top

Is Powerflow flux safe for gas pipes?

It is advisable to use either Fernox Flux or Fluxite, which are acid free for gas pipes.

Back to top

Are Fernox Protectors/Cleaners/ Boiler Noise Silencers/Leak Sealers suitable for use on systems with plastic pipe (or Speedfit fittings)?

Yes, all Fernox products have been formulated for use with plastic pipe work and are compatible with Speedfit fittings.

Back to top

Can I add Fernox Boiler Noise Silencer F2 or Fernox Leak Sealer F4 to my system even though it has previously been treated another manufacturer's inhibitor?

Fernox Boiler Noise Silencer F2 has been developed to have no harmful or detrimental effect on a boiler or central heating system. It is proven to reduce the kettling and banging sounds produced by a boiler in systems that have not been correctly treated.

We would advise the system is properly cleaned and treated with Fernox products but in the interim Fernox Boiler Noise Silencer F2 is safe to use to alleviate a noise problem. The same policy applies to using Fernox Leak Sealer F4.

Back to top

My combination boiler keeps loosing pressure, what can I do?

Fernox Leak Sealer F4 is formulated to seal small leaks and weeps in central heating systems which cause system pressure to drop.

Reoccurring problems need expert advice and we would recommend you contact your installer.

Back to top

My boiler is noisy, what should I use to clean it?

If the oldest part of the system (pipes/radiators/boiler) is less than 15 years old, clean the whole system with Fernox DS-40 System Cleaner, which is an acid cleaner. Otherwise, a restricted circuit clean on the boiler/cylinder/ one radiator with Fernox DS-40 System Cleaner followed by a thorough cleaning of the whole system with Fernox Cleaner F3. Finally treat with Protector F1 and Boiler Noise Silencer F2 in combination.

Back to top

Where can I buy 'Fernox crystals'?

Fernox Limescale Preventer is available in crystal form. It is the bag of crystals that hangs in your cold water storage tank to prevent lime scale formation. It is available at all good plumbing merchants and High Street DIY stores.

Back to top

How long does Fernox Limescale Preventer last?

Averagely the product lasts six months depending on water usage and water hardness level.

Back to top

If the crystals have not all dissolved after more than six months, do I still need to change them?

Yes, the active ingredients will have been leeched out after this period so it is necessary to change the bag every six months for full protection.

Back to top

Fernox Limescale Preventer instructions state that the product treats water up to 400ppm hardness but my mains water is only 200ppm hardness, does this mean the product will last longer?

No, irrespective of water hardness levels, the product should be changed every six months as it will be exhausted after this period.

Back to top

Is Fernox Limescale Preventer safe to use to clean mine or my children's teeth?

Yes, it is a food grade material that is approved for potable/drinking water.

Back to top

If I empty my central heating system, can I drain the contents to my septic tank?

Yes, there is no problem.

Back to top

When I empty my central heating system, can I drain the contents over my lawn/garden?

No! Even though Fernox protector products are non hazardous, some products may not have the same status. It is illegal to pour the waste water from a central heating system into ground water as this could contaminate waterways/rivers/streams. It will also very probably scorch your plants. So, you should always drain to foul drains - as per toilet waste.

Back to top

How much Fernox Protector do I need for a system with ten radiators?

One pack of any Fernox Protector will treat a typical 100 liter system with ten single panel radiators. If you have double panel radiators, you should count these as two items when calculating how much inhibitor will be needed. If the calculated dose rate is in between carton sizes, dose to the higher figure.

Back to top

Can I overdose with Protector?

No! Overdosing is not detrimental and it is important to ensure that there is always sufficient treatment present. There is a dip test kit and a postal testing service available to check your Protector concentration. See Protector Test Kit product data sheet.

Back to top

Is it safe to empty my central heating water down the drain?

Yes, in fact you should only drain your central heating system into mains drainage or a septic tank. Never drain your system into rain water gullies, as these go directly into rivers without treatment. Never pour water from a central heating system on the garden or a lawn.

Back to top

Can Fernox Leak Sealers be used in combination boilers?

Yes, all internal Fernox Leak Sealers F4 are safe for use with combination and other low water content boilers. They will not block valves or vents. We recommend Fernox Express or Superconcentrate Leak Sealer F4 products for all pressurized systems as they can be easily added via a radiator in a few minutes, without draining out any water.

Back to top

What causes knocking noises in boilers?

Boiler noises result from localized boiling of the water. This happens when the inside surface of the boiler becomes too hot due to scale or baked on sludge deposits. All systems over five years can suffer noise and new boilers in old systems are especially vulnerable. We recommend you clean the boiler and system with one from the range of Fernox Cleaners, or add a Fernox Express or Superconcentrate Boiler Noise Silencer F2 product to the system as an interim measure.

Back to top

Do you make anything to get rid of air?

Air collecting in radiators can be formed either by a system fault that causes air to be sucked into the system, or by corrosion that generates not air, but hydrogen gas. Suction air is a design fault that must be remedied by improving the system layout and cannot be resolved by treatment. Hydrogen gas problems can be easily corrected by cleaning with Fernox Express or Superconcentrate Cleaners F3 or F5 and by adding an Express or Superconcentrate Protector F1 product.

Back to top

Are Fernox formulation compatible with plastic pipe and push-fit fittings?

Yes, all Fernox products are safe to use with plastic pipe and push-fit fittings from the leading suppliers.

Back to top

Does Fernox contain mineral oil?

Fernox Protectors and cleaning agents do not contain mineral oil.

Back to top

What is a Primatic system?

This is a name given to what is properly termed a single feed cylinder, which is an arrangement whereby the central heating expansion is taken up by an air bubble within the cylinder.

To identify a Primatic cylinder use the following check list:

Hot water cylinder fitted (airing cupboard) – YES

Cylinder is labeled Primatic / Single feed cylinder – YES

Cold water tank in loft – YES

Second small open tank (F&E) fitted in loft/airing cupboard – NO

Combination boiler – NO

Solid fuel stove/boiler – NO

Filling loop, valve and pressure gauge to fill radiator system – NO

If you get an alternative answer to any ONE of the above questions to that stated, then you are likely to have a Primatic cylinder and you must NOT use any Fernox product.

Back to top

Do Fernox Cleaners need to be flushed out of the system?

Cleaners should be allowed to circulate around the system for at least 1 hour for new systems, or up to a week for existing systems, then drained out and the system flushed thoroughly before adding Fernox Protector F1.

Back to top

Is the Fernox Flux self-cleaning?

Yes. Fernox Flux is self-cleaning, but it is non-acidic.

Back to top

How do I get a copy of an MSDS file/sheet?

All Safety data sheets for each Fernox product are downloadable from the Fernox website. The information is available in over 30 languages. If there are additional requirements please email

Back to top

Why are filters of any kind required when a proper cleanse and inhibitor job has been completed on a system? Is it simply to act as an indicator of a failed job?

The older the system, the more sludge that is likely to be present to remove during cleaning, but the paradox is that on the older systems you also have to clean more gently due to risk of leaks. This means that less aggressive cleaners have to be used, and even with Powerflushing perhaps only 80% of the debris is removed. You could remove 100% of the debris by acid cleaning, but with risk of leaks and consequent damage to the property, plus cost of replacement leaking radiators perhaps. The amount of acid (say Fernox DS-40) is also directly related to the amount of sludge. It might take 5 packs or more of DS-40 to 100% clean an old system at a considerable cost in chemicals and extra labor = five flushes. So, there is also a consideration of cost-effectiveness here. Powerflushing is a labor intensive process as we know. Therefore, the up-shot is that you have to look upon cleaning and Powerflushing as a risk management process not a means of returning the system to totally pristine condition. The more debris that you take out, the more efficient will be the system (a 15% gain in efficiency from experimental evidence) and the less the risk of breakdown. One reasonable clean plus a filter is more cost effective than many cleans to achieve 100% sludge removal.

The purpose of the filter is therefore to give additional protection to the system, especially to the boiler, pump and motorized valves, from any remaining debris that is loose and mobile in the system. Design changes to the system at the time of cleaning such as installation of a new boiler or pump, TRVs etc., may have changed flow patterns within the circuit and this can lead to re-distribution of remaining debris.

Also, it is found that there is a tendency for suspended debris to be present in the water in the immediate period after cleaning and this too will be captured by the filter. Thin films of adherent debris may break off plastic pipes after cleaning – so called ‘tea leaves’ - and cause blockages.

To assess if the cleaning job has been done well, check the filter periodically. In the first month there will be the most deposits but this should reduce significantly by month 3. If a high level of deposit continues to be removed by the filter even say 6-12 months on from the clean then this is obviously not satisfactory and would indicate that further cleaning would be desirable.

Back to top

Submit a question