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 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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