Viewpoint: We need a way to compare system filters

Martyn Bridges

The British Standard 7593 code of practice has made it a requirement for a system filter to be permanently installed into heating systems. Martyn Bridges, director of technical communication and product management at Worcester Bosch, explains why we should consider performance testing of filters as we move forward.

A lot can change in 13 years in the heating industry. The recent publication of the BS 7593, the British Standard code of practice for the preparation, commissioning and maintenance of domestic central heating and cooling water systems, is an update to the 2006 publication and demonstrates just how far we have come both in terms of technology and best practice.

One of the major changes in that time has been the advent of system filters. The most popular are magnetic system filters, which attract most of the iron oxide in the system in order to avoid metallic contamination of the water.

They can then be cleaned and potential contamination removed. System filters have been a relatively new component of a heating system and from virtually no sales 10 years or so ago now account for around 1.1 million sales annually with some manufacturers, including ourselves, extending the warranty of the boiler when a filter is fitted.

Clearly, component parts of the boiler are less likely to break down if there is something to stop contamination flying around the system. In the early days however, there were some instances where it was felt the installation of a filter removed the need for a full flush and cleanse – but this isn’t the case, and often resulted in a system actually worse than a cleansed system.

System filters are now much more commonplace. Of the 1.6 million boilers fitted per year, there are over a million system filters fitted within.

There is a difficulty, however. It’s impossible to gauge the performance of a system filter and therefore compare which is better than the other. There are some recognised brands and market leaders who have a great heritage and history. Despite there being tens of filters available, there is no clear indication of quality and no way to compare besides price or marketing claims. With other products such as boilers, vacuum cleaners and cars you can tell which one is going to perform better and there is a standard which they’re designed to.

With boiler efficiency as an example, different systems are in use: ErP, SEDBUK 2009, and SEDBUK 2005.

They’re all dependent on slightly different calculations and while it’s not ideal to have several rating systems, they’re easy enough to understand. ErP is the simplest, and each new energy using product carries an ErP energy label, which ranks its efficiency from A+++ (the best) to G (the worst).

The water treatment industry might need to consider a similar performance criterion for system filters, which suppliers can all agree on and test their filters to in order to provide individual ratings. This would then allow for the creation of a certain standard which all filters have to adhere to.

Installers would then be able to know the quality of the filters that they are fitting and how they stack up against rival products.