Published in May 2019 the new BS 7593:2019 provides clear guidance on the preparation, commissioning and maintenance of domestic central heating and cooling water systems. Here, Francine Wickham, Global Marketing Director at Fernox takes a look at the revised code of practice and explores the latest product innovations available, to make it easy for installers to comply.

For many years the chemical water treatment industry has been championing life-long protection of central heating systems, to improve energy efficiency, minimise fuel wastage and ensure system longevity – and as a leading member of the BEAMA water treatment committee, Fernox has played an active role in the development of the latest revisions to  BS 7593:2019, which aims to clarify and promote best practice, for the lifetime of the system.  

Fernox supports the new legislation through its Research and Development programme, as the company recognises the crucial role product innovation and application must play in encouraging the wide-spread adoption of new practices and processes – where ease of use and reliable product performance is key. 

The latest code of practice covers five key areas – clean, guard, protect, maintain and test – to not only ensure compliance but to also ensure systems are performing at their optimum level.

  1. Clean

Before an existing central heating system is dosed with chemical water treatment or a filter is installed, it is vital that it is cleaned to remove any existing sludge or debris build-up. For best results, installers should use a recognised cleaning method such as powerflushing, mains pressure or gravity cleaning.

It is also important that systems are cleaned before the boiler is installed or when a new boiler has been isolated from the rest of the system. This will prevent any existing sludge or debris within the system reaching and depositing in the boiler and causing lasting damage.

  • Guard

Once a central heating system is cleaned, it is key to make sure that sludge and debris does not build-up once more. The new BS 7593:2019 code of practice states that, in order to do this, an in-line filter should be permanently installed to provide continued protection and maintain system efficiency.

It is important that the chosen filter can effectively capture and contain both magnetic and non-magnetic debris to keep the system as clean as possible. Filters manufactured by leading water treatment specialists, that utilise a powerful neodymium magnet and other technology such as Hydronic Particle Separation (HPS) are better able to achieve this – and can therefore deliver optimum results.

For ease of install, it is important to consider whether the filter can be installed in a variety of orientations, such as horizontal, vertical, or with the capability of being installed up to 45° orientation in order to fit small confined spaces, such as the Fernox TF1 Filter range.

  • Protect

To protect a central heating system from corrosion, scale, microbial fouling for low temperature heating systems, installers should dose the system with the correct quantity of chemical water treatment products. This should include Protectors to protect against harmful sludge and debris build-up. It is best to choose products from a reputable manufacturer, to guarantee that the chemicals will continue to protect the system effectively.

It is also important that systems are dosed correctly – the Fernox ‘F’ range of chemicals, for example, have recently been re-formulated to include more active ingredients; and can now treat systems up to 130 litres, 16 radiators, or underfloor systems up to 250m2. This will significantly lower the chance of under dosing, to cover 97% of UK homes.

For low temperature or underfloor heating circuits, which are at risk from bacterial contamination and fungus, specialist biocides are available. Fernox Biocide F7, for example, protects against bacterial slimes, algae and biofilms forming, which can cause blockages, inefficiencies and ultimately breakdowns.

In order to meet the requirements of BS 7593:2019, it is vital that installers look to specialist manufacturers who demonstrate an understanding of the on-site challenges, with an extensive product portfolio that offers a solution for every application – and ensures compliance on every project.

To find out more about Fernox’s range of products or to speak to a Fernox representative regarding the new legislation visit