Fernox 'How to Sheets' are designed to help you use our products to best effect by maintaining the smooth running of your central heating system; saving time and money on maintenance and repair as well as conserving fuel and reducing carbon emissions.

  • How to disinfect a water system

    How to disinfect a water system

    Disinfection is a process which destroys or irreversibly inactivates micro-organisms, reducing their numbers to a safe level.

    Its purpose is to leave a clean water supply. It must be carried out in the following circumstances:

    • During routine annual system maintenance
    • New installations n After major system extensions or alterations
    • After installing underground pipework, except localised repairs which require prior disinfection of components
    • Where it is suspected that contamination may have occurred: i.e. fouling by sewage, or if systems have been inspected or repaired
    • Where a system has not been in regular use nor regularly flushed

    What should be done?
    Fernox offers two options for disinfection: traditional chlorination using Fernox Sterox or a silver catalysed hydrogen peroxide treatment, Fernox LP Sterox.

    Fernox Sterox Kit
    The Fernox Sterox kit contains 15 tablets of sodium dichloroisocyanurate (each containing 12.5 grams of available chlorine), a test kit sufficient to carry out 50 tests and full usage instructions. With one kit, 1675 litres (375 gallons) of water can be disinfected.

    When using Fernox Sterox for chlorination it is important to ensure that all of the chlorinated water is flushed out sufficiently (at least two complete changes or water) following treatment.

    Fernox LP Sterox
    This product treats a wide spectrum of biocidal activity including all water-borne bacteria and viruses. It is particularly valuable in modern water system hygiene management where more conventional treatments such as chlorination are unsuitable. Fernox LP Sterox is supplied in one litre bottles. This will treat 300 litres of system water. After treatment, it is not critical that Fernox LP Sterox is flushed from the water supply as it naturally decomposes to water and oxygen.

    Water should be run from each outlet and tested with a Fernox LP Sterox Test Strip until the concentration in the water is less than 200ppm.

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  • How to estimate the volume of a water system

    How to estimate the volume of a water system

    The following guide to estimating system volumes has been developed, based on field experience. Commercial systems (pressurised):

    Multiply the boiler output rating in kWs by the figure detailed below (for the relevant type of system) to give an estimate of the total system volume. Allow an additional 10% (multiply by 1.1) for open vented systems of all types.

    Useful conversion factors:

    Systems comprising perimeter heating, convectors, etc. 6 litres/kW
    Ventilation systems (air handling units, fan coils, etc.) 8 litres/kW
    Steel panel radiators 11 litres/kW
    Cast iron radiators 14 litres/kW
    ‘Distant’ heating systems in large sprawling buildings 20 litres/kW
    Underfloor heating 23 litres/kW

     

    Domestic systems:

    All small and microbore domestic installations 6 litres/kW n

     

    • The domestic system volume can be estimated by counting the number of single panel radiators in a property and multiplying by 10
    • Remember to count double panel radiators as two single panels
    • It is also important to consider thermal stores, which can add up to 100 litres to system capacity

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  • How to repair system leaks

    How to repair system leaks

    Leaks in water systems can result from external frost damage, dry solder joints, accidental perforation during maintenance or decoration, or internal corrosion.

    Sealing internal leaks (central heating systems only)
    Small leaks, including pressure drops on combination boilers and other sealed systems, can be repaired using Fernox Leak Sealer F4. Each Leak Sealer F4 product treats 100 litres or up to 10 single radiators.

    On an open vented system, pour the Leak Sealer F4 into the tank and simply draw off 5-10 litres of water from the drain cock initially returning this to the header tank to ensure that no treated water is thrown away. Repeat the previous step until all Leak Sealer F4 has been absorbed into the circulating system.

    Switch on the circulating pump and apply at least a small amount of heat to achieve even distribution.

    An alternative solution for dosing is to inject Fernox Leak Sealer F4 Express or Fernox Superconcentrate Leak Sealer F4 directly into the radiator via the bleed valve.

    Repairing external leaks (to all types of water pipes)
    To repair leaking external pipes and fittings, use Fernox LS-X External Leak Sealer with a bandage of PTFE tape or another suitable reinforcement tape.

    After turning off the water and draining down to remove water pressure from the leak, apply Fernox LS-X External Leak Sealer to a dry surface around the area of leakage. Wrap the pipe with a layer of PTFE tape or other reinforcement tape with 50% overlap and extend well beyond the area of the leak.

    Immediately apply repeat coats of Fernox LS-X External Leak Sealer and further layers of bandage to form a repair about 5mm in total thickness before allowing to cure.

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  • How to combat problem limescale

    How to combat problem limescale

    Minerals in chalk or limestone rock collect as water permeates through the ground and collects in aquifers. These minerals remain within the water and are carried into the domestic water supply.

    What causes limescale deposition?
    They inevitably reach central heating and water systems, where they build-up over time to cause blockages in pipework, efficiency losses and the premature failure of components. These problems can arise in both the primary water system (the central heating system) and secondary (household hot water) system.

    The mineral deposits, collectively known as limescale, consist primarily of calcium and magnesium carbonates which are generally insoluble. Limescale occurs when these deposits are formed as a result of heating water that contains soluble bicarbonate salts (which are thermally unstable and break down to form carbonates).

    There are several factors that contribute to the build-up of limescale, including:

    • High (temporary) hardness
    • Elevated pH (alkalinity) of the water
    • Elevated temperature

    What should be done?
    Prevention is always better than cure. In central heating systems, the addition of any Fernox Protector F1 will prevent deposition of limescale.

    For domestic hot water systems, Fernox offers a range of scale reducers designed to provide either whole house or single appliance protection.

    For whole house protection, the Fernox Electrolytic Scale Reducer should be installed on to the mains water supply to the property. To protect single appliances such as the boiler, the Fernox Magnetic Scale Reducer is ideal.

    If the central heating system is already contaminated with limescale it should be cleaned using an acid-based cleaner such as Fernox DS40 System Cleaner. However, descaling alone will not restore the central heating system to its original condition. After descaling it is imperative to protect the system against further scaling by adding any Fernox Protector F1 or if a system filter is fitted Fernox Filter Fluid+ Protector.

    If limescale formation has occurred within the hot water system, individual appliances such as kettles, showerheads and heat exchangers can be descaled using Fernox DS-3 Limescale Remover. For open vented systems Fernox Superconcentrate Limescale Preventer is an ideal way to keep system water scale-free.

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  • How to reduce fuel wastage in heating systems

    How to reduce fuel wastage in 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 its efficiency has dropped.

    What causes fuel wastage?
    There are two main forms of deposits found in heating systems:

    Part L of the Building Regulations for England and Wales 2006 states that new all wet central heating systems should be pre-commission cleaned and treated with a central heating inhibitor. The correct method for inhibiting a central heating system is explained in a British Standard Code of Practice BS 7593:2006. If the cleanliness of a central heating system is maintained from the start, its life span can be extended as well as design efficiency optimised. However, if the efficiency of an existing system has been reduced due to a lack of cleaning or insufficient inhibition protection, remedial action should be taken. Fernox Cleaner F3 and Fernox Powerflushing Cleaner F5 are both designed to recondition systems and are particularly effective if the system is contaminated with black iron oxide sludge. Fernox DS40 System Cleaner should be used if limescale deposition is evident. However, it is important to note that cleaning or descaling will never fully restore the heating system to its original condition. After cleaning, the system should be protected against further corrosion or scaling by using Fernox Protector F1 or Fernox Protector MB-1, or in systems where a system filter has been installed, Fernox Filter Fluid+ Protector can be used.

    • In hard water areas, limescale forms mainly on the hottest surfaces. Low water content and tubular boilers are particularly prone. High skin temperatures can attract lime even from relatively soft waters, but these are unlikely to cause limescale problems. However, temperature is not the only factor that can promote limescale deposition. The design of components or choice of material and surface finish can all increase or decrease the probability of scaling. As modern condensing boilers have far narrower flow channels in the heat exchanger than older cast iron boilers, less deposition is required to cause noticeably detrimental effects to system performance. Limescale deposition that affects system performance can begin from waters containing as little as 100ppm of hardness.
    • Black iron oxide sludge is produced continuously in all untreated installations, even in the near absence of air or dissolved oxygen, mainly due to electrolytic corrosion. If there are higher levels of dissolved oxygen (perhaps because of an aeration fault) it compounds the problem. Iron oxide is five times heavier than water and settles in areas of reduced flow such as radiators.

    As well as wasting fuel, these deposits cause other problems such as boiler noise and component failure, notably relating to circulator pumps and boiler heat exchangers.

    Part L of the Building Regulations for England and Wales 2006 states that new all wet central heating systems should be pre-commission cleaned and treated with a central heating inhibitor. The correct method for inhibiting a central heating system is explained in a British Standard Code of Practice BS 7593:2006.

    If the cleanliness of a central heating system is maintained from the start, its life span can be extended as well as design efficiency optimised. However, if the efficiency of an existing system has been reduced due to a lack of cleaning or insufficient inhibition protection, remedial action should be taken.

    Fernox Cleaner F3 and Fernox Powerflushing Cleaner F5 are both designed to recondition systems and are particularly effective if the system is contaminated with black iron oxide sludge. Fernox DS40 System Cleaner should be used if limescale deposition is evident. However, it is important to note that cleaning or descaling will never fully restore the heating system to its original condition. After cleaning, the system should be protected against further corrosion or scaling by using Fernox Protector F1 or Fernox Protector MB-1, or in systems where a system filter has been installed, Fernox Filter Fluid+ Protector can be used.

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  • How to dose a system with Fernox Express

    How to dose a system with Fernox Express

    Follow these steps to successfully dose your central heating system.

    Make sure the system is turned off and allow radiators to cool down (1). Select a radiator and shut both the wheel-head and lock shield valves (2). If a thermostatic radiator valve (TRV) is fitted, close it by turning it to the minimum setting.

    Having removed the air vent pin using a cloth to absorb any escaping water (3). Screw the Fernox Express injection nozzle into the air vent (after cutting to the right diameter to fit tightly (4)). Fit the tube to the adapter and screw onto the canister. Attach the other end of the tube onto the nozzle in the radiator (5).

    Re-open the wheel-head valve (6) (or TRV) and inject all the content of the Fernox Express by squeezing the trigger for 30 seconds (7). After the product has been dispensed close the wheel-head valve (8) (or TRV), remove the injector nozzle and tighten the air vent pin (9). Open both radiator valves, turn on the central heating system (10) and let it run for 15 minutes to allow the Express to disperse around the system.

    Fernox Express can also be for dosed via the system filling loop using the appropriate special adapter supplied with the Express product as well as via the bleed valve on a fitted Fernox TF1 Filter. The whole process takes less than two minutes.

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  • How to descale a hot water system manually

    How to descale a hot water system manually

    The damaging effects that limescale can have on the lifespan of a boiler and the energy efficiency of a central heating system are significant. Part L of the Building Regulations stipulates that where mains hard water exceeds 200 ppm, feed water to water heaters and the hot water circuit of combination boilers must have a scale reducing device fitted.

    Why is descaling important

    Limescale prevention
    An effective method of treating water to avoid the build-up of limescale is to install an in-line Fernox Scale Reducer. An Electrolytic Scale Reducer will provide whole house protection, while a Magnetic Scale Reducer is suitable for single appliances. Both products can be easily connected directly onto 15 mm or 22mm horizontal or vertical pipe work using compression fittings or 15mm horizontal or vertical pipework using 15mm pushfit fittings.

    Limescale removal
    Where limescale has already formed it can be removed from a hot water system, including the storage cylinder, immersion heater, pipework and taps using Fernox DS-3 Cleaner.

    After turning off the boiler and/or immersion heater, tie-up the ball valve or isolate the mains water supply to the cold water storage tank. Then open all hot water taps before draining the entire system, and close the taps again afterwards.

    Having dissolved the Fernox DS-3 in warm water at the maximum concentration of 1kg per 10 litres of water, introduce the solution into the cold water storage tank either via a funnel connected to rubber or plastic tubing or directly, if the cold water storage tank serves the hot water cylinder only. Refill the system until the water level in the cold water storage tank just covers the cylinder feed connection. After this is done, turn on the boiler and/or immersion heater and heat the acid solution in the hot water cylinder to 50-60°C. Maintain this temperature for at least four hours, opening all hot water taps briefly every 10-15 minutes to allow a half to one pint (284 to 568ml) of acid solution to run into a plastic container. Finally, turn off the boiler and immersion heater, and drain the hot water system completely, bailing out any residual water from the cold water storage tank.

    Release the ball valve of the cold water storage tank and thoroughly rinse the entire hot water supply system, opening all hot water taps. Where applicable the cold water system should also be rinsed, as some acid may have entered via the cold water storage tank. Any waste solutions of DS-3 Cleaner should be neutralised with Fernox System Neutraliser before discharging to the drain.

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  • How to prevent corrosion

    How to prevent corrosion

    Corrosion occurs when a refined metal reverts back to its natural ore state. Corrosion in water systems takes place when two areas of metal with a different electrical charge are in contact or linked via a conductor such as water.

    Corrosion occurs when a refined metal reverts back to its natural ore state. Corrosion in water systems takes place when two areas of metal with a different electrical charge are in contact or linked via a conductor such as water.

    What should be done?
    An inhibitor should be added to system water to reduce the rate at which corrosion takes place. To determine the existing level of protection simply use the Fernox Protector Test Kit to measure the concentration of inhibitor within the system for an instant on-site result.

    Over and under-dosing with inhibitors
    Although manufacturers specify a recommended dose rate for their product, it is important to find out how a product performs when over or under-dosed. Anodic passivating products will require a sufficient dose to ‘coat’ the internal surfaces of the system, plus some excess to maintain this film. If the dose is below the level required to achieve sufficient protection, exposed areas of metal will continue to corrode. Over-dosing with anodic inhibitors is unlikely to have any detrimental effect.

    Negative impact of contaminants
    However, corrosion inhibitors will not be fully effective if under-dosed, but will have a partially protective effect. Negative impact of contaminants The presence of contamination by flux residues, existing corrosion sludge, residual cleaning agent, or even washing-up liquid may adversely affect the performance of an inhibitor and lead to corrosion. To make sure an inhibitor performs as effectively as possible, it is advisable to clean the system thoroughly before treating. the Fernox Water Test Kit, the Fernox F3/ F5 Cleaner Test Kit or the Total Dissolved Solids (TDS) Meter can be used to check that a system has been adequately cleaned and flushed before an inhibitor is added.

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  • How to clean a heating system

    How to clean a heating system

    Systems should be cleaned when commissioning a new system or installing a new boiler within an existing system. The purpose of cleaning and flushing is to remove mineral oil, harmful flux residues and installation debris which can cause corrosion.  Cleaning existing systems removes magnetite (black iron oxide), haematite (red iron oxide) and limescale improving the circulation and reducing fuel wastage and boiler noise.

    New systems domestic 
    Fernox Cleaner F3 or Fernox Powerflushing Cleaner F5 should be added before commissioning the system. Simply circulate FernoxCleaner F3 or Fernox Powerflushing Cleaner F5 for at least one hourwhen the boiler is switched on, after which the system should bedrained and thoroughly flushed until the water runs clear.

    Existing systems domestic
    Ideally the system should be powerflushed to remove any existing treatment, sludge and contaminant. Fernox Cleaner F3 or Cleaner F5 should be added to system water and circulated hot for at least one hour after which the system must be drained and flushed until the water runs clear. The cleaning time can be extended to up to one week for systems which suffer from hardened iron oxides and limescale.

    For both new and existing systems, a Fernox TDS Meter should be used to ensure efficient flushing by comparing the readings of the system water and mains water. The system is thoroughly flushed if the readings are within 10% of each other.  Alternatively, the Fernox Cleaner F3/F5 Test Kit can be used to determine the level of cleaner residues remaining in the system.

    Protecting new and existing systems
    In accordance with Part L of the Building Regulations, after cleaning with Fernox Cleaner F3 or Fernox Powerflushing Cleaner F5, add Fernox Protector F1 with the final fill water for long-term protection against corrosion and limescale.

    All Fernox Protector/Inhibitor products are compatible with commonly used metals in central heating systems, including aluminium, and are suitable for use with plastic pipework. For continued protection, check Protector/Inhibitor levels annually using the Fernox Protector Test Kit or the Fernox System Health Check postal service and top up product level as required.

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  • How to reduce boiler noise

    How to reduce boiler noise

    Boiler noise is usually the result of limescale deposition within the heat exchanger of a boiler. This condition is worsened if magnetite is also present in the system, as this combines with the limescale to form a much harder deposit.

    Boiler noise is usually the result of limescale deposition within the heat exchanger of a boiler. This condition is worsened if magnetite is also present in the system, as this combines with the limescale to form a much harder deposit. Other sediment forming debris such as sand and brick dust entering the system during installation can also become part of the hardened deposit. Local water conditions also play an important part, particularly the scale-forming solids dissolved in the supply water.

    Boiler noise is directly related to the rapid condensation or implosion of steam in water. Localised boiling develops on the surface of the deposit, and small steam bubbles are created that make a rattling noise as they leave the surface and travel around the system.

    When installed into existing systems, new boilers can become excessively fouled soon afterwards by oxide sludge present in the system water. Replacing a boiler can disturb soft sludge and loosen sediment in other parts of the system, causing these contaminants to be transported by the system water and re-deposited in the new heat exchanger.

    The same phenomenon can occur as a result of circulator replacement if flow rates change. The risk of sediment and sludge deposition in new boilers can be avoided by cleaning the system as part of the installation process. Guidance on correct cleaning and treatment can be found in BS 7593:2006 Code of Practice for Treatment of Water in Domestic Hot Water Central Heating Systems.

    What should be done?

    Fernox Boiler Noise Silencer F2 is specifically formulated to significantly reduce boiler noise by reducing the surface tension of the system water. The reduced surface tension prevents large bubbles from being able to form and so the associated noise is greatly lessened.  Fernox Boiler Noise Silencer F2 efficiently treats the effects of a noisy boiler until the causes can be treated with a full clean of the system.

    Fernox DS40 System Cleaner selectively dissolves scale deposits without attacking the metals commonly found in central heating systems. However this acid-based cleaner should only be used in new installations or in systems less than 10 years old.

    Older systems that have been untreated for periods of time may have existing leaks that are temporarily plugged with corrosion debris. Installations with a history of radiator corrosion failures should not be acid cleansed, as other radiators are likely to have deep corrosion pits or complete perforations.

    Older installations can be substantially improved, however, by dispersing the sludge with Fernox Cleaner F3 or Fernox Fernox Powerflushing Cleaner F5, followed by powerflushing with plain water.

    After removing all soft sludge from older installations, separate boiler de-scaling may be helpful to resolve the problem. In order to do this, all the radiators should be isolated after which the system can be descaled with Fernox DS40 System Cleaner over a period of time – up to 24 hours.  This process should be followed by neutralisation with Fernox System Neutraliser before powerflushing with plain water.

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  • How to avoid bacterial contamination

    How to avoid bacterial contamination

    Algae in feed and expansion cisterns Leathery skins or films of algae on the surface of expansion cisterns in open vented systems are caused by fungal mould growths. It occurs when the expansion cistern is not properly covered causing dust, insects and spores to be able to enter the water.

    Algae in feed and expansion cisterns
    Underfloor heating systems are also susceptible to microbial growth due to the lower temperatures at which these systems operate.

    Gas in the system
    Microbiological fermentation in a system could result in flammable gas. Methane gas, which burns with a blue flame, is most often found.Hydrogen sulphide (emitting a ‘bad egg’ smell) may also occur, and is associated with the presence of corrosive sulphate-reducing bacteria.

    Bacterial or yeast infestations caused by organisms entering the system from the supply water; debris in new systems or through air contact in open expansion cisterns can also occur.

    What should be done?

    To combat algae in open vented systems, empty the cistern and disinfect with Fernox AF-10Biocide or Fernox LP Sterox. Refill the tank, adding the correct dose of AF-10 Biocide (refer to the instructions on the container)and top up the concentration levels of Protector F1. Ensure the tank is fitted with a purpose-made lid to prevent future contamination of the tank.

    When there is gas in a system,use Fernox AF-10 Biocide to control microbiological growths and prevent gas build-up. Where contamination is significant,several repeat doses of biocide may be required: in such situations, it may be appropriate to drain and retreat the entire system.

    Bacterial contamination in air and ground source heat pumps
    When there is bacterial contamination in air and ground source heat pumps, Fernox HPCleaner can be used.

    Before use, it should be diluted using no more than 600 litres ofmains water per one litre of HPCleaner (equivalent to 600 metres of 40mm pipework). The ground collector must be flushed out with fresh mains water before being filled with the diluted product.Having circulated the HP Cleaner for at least one hour, after whichit should be flushed out until thewater runs clear. Fill the ground collector with Fernox HP-5 /HP-5c or HP-15 / HP-15c depending on the level of frost protection required.

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  • How to dose using Superconcentrate Cartridge 29oml

    How to dose using Superconcentrate Cartridge 29oml

    The Fernox Superconcentrate range uses a patented injection system to add treatment gels directly into a system via radiator vents. This process removes the need to drain down systems, saving both time and money.

    The Fernox Superconcentrate range uses a patented injection system to add treatment gels directly into a system via radiator vents. This process removes the need to drain down systems, saving both time and money.

    Make sure the system is switched off and allow radiators to cool down. Select a radiator and shut both the wheel-head and lock shield valves. If a thermostatic radiator valve (TRV) is fitted, close it by turning it to the minimum setting.

    Having removed the air vent pin using a cloth to absorb any escaping water, screw the Fernox Superconcentrate injection nozzle into the air vent (after cutting to the right diameter to fit tightly). Remove the foil from the base of the cartridge and cut off the seal above the thread at the top using a sharp knife. Fit the tube to the adapter and screw onto the cartridge, placing the cartridge into a mastic gun. Attach the other end of the tube onto the nozzle in the radiator.

    Re-open the wheel-head valve (or TRV) and inject all the Fernox Superconcentrate into the radiator with the cartridge gun. Afterwards, close the wheel-head valve (or TRV), remove the injector nozzle and tighten the air vent pin. Open both radiator valves, turn on the central heating system and let it run for 15 minutes to allow the Superconcentrate to disperse around the system. 

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