Filtering for protection

Ian Roberts considers how magnetic filtration can help provide long-term protection for commercial plant rooms as the ErP Directive drives change.

With the objective of improving energy efficiency, the ErP Directive has supported the introduction of more modern boilers. Although welcomed by the industry, the development has highlighted the problem and threat posed by corrosion to commercial heating systems.

This is an issue not to be underestimated. Ensuring steps are taken to mitigate damage will help to maximise value in commercial plant rooms. It is also important we consider risk versus performance. When these are equally balanced, we are at compliance. However, tipping this scale to lower risk and raising performance is what you should be aiming to do. To achieve this, a best practice approach is most effective, and this will include the adoption of magnetic filtration as part of a complete water treatment programme.

The problem is caused by magnetite which makes up around 98 per cent of system debris and is a direct result of corrosion that occurs when water circulates through boilers and pipework. However, magnetite particles are very small, measuring just eight microns (0.088mm) in diameter, which makes capturing them difficult. It also means they can travel easily around a heating system, deposit in low flow areas such as heat exchangers, base boards and radiators, cause erosion in turbulent areas, and clog up pumps.

As part of the adoption of ErP, older, more tolerant but less efficient cast iron boilers have been replaced with more efficient stainless steel and aluminium models. These newer generation boilers cannot match the durability of cast iron units unless the proper protection is in place. They are smaller which means their heat cells are more prone to magnetite blockages while the small waterways, reduced from 50-60mm to as small as 8mm in some cases, are also susceptible to becoming blocked. While the industry has been quick to respond to these legislative changes, in the most part it has failed to react to the implications these advances in technology have on long-term system performance. This is leaving a large proportion of heating systems vulnerable to breakdown. There is now widespread adoption of magnetic filtration in the domestic sector, with installers very much in tune with the benefits it can bring. Replacing a boiler in the home is an expensive exercise but when you consider this in a commercial context, the associated costs will be multiplied many times. Based on our experience, we estimate that to protect a domestic boiler an investment of around 15 per cent of the capital cost is usually made but in a commercial context it's more likely to be around 1 per cent.

Historically, dirt and air separators have provided much of the protection for commercial systems. However, the mesh used to capture the magnetite particles is not small enough, leaving sludge to circulate round the system. Technology has now moved on and been replaced with a far more effective way of protecting expensive plant rooms. As the name would suggest, magnetic filtration has magnets as its core. These are usually powerful neodymium magnets which are tolerant to high temperatures and available in different sizes depending on the size of the system.The filter can easily be fitted to the pipe work and this can be done on a brand-new heating system or retrofitted. The filter will also need to be monitored, emptied and serviced as the sludge collects around the magnets. Some filters also offer greater flexibility, with both side stream and in-line installation being possible.

Specifying magnetic filtration from the start will ensure investment in large and expensive systems is properly protected. There is a real need for more widespread adoption of the technology but for this to happen, greater awareness and education about its benefits must be understood and spread throughout the industry. Specifiers and facilities managers can tallc to their contractors or maintenance teams to ensure the message is getting through. Perhaps the biggest problem is that many are still relying on older technology without realising that it is an ineffective way to capture magnetite.

Embracing technology

One example of how magnetic filtration has made a real difference is at University College London. The university comprises 422 buildings, including academic sites, research laboratories, student accommodation and energy centres. In London alone, this translates to 320 boilers which started undergoing a substantial and complex replacement programme last year. Protecting these boilers is a significant and ongoing priority for the facilities team, and given what they serve, maintaining good performance is paramount, so UCL turned to magnetic filtration to help protect its investment. Currently more than 60 commercial filters have been installed ranging in size from 2" to 6". This is part of a planned maintenance programme being rolled out over at least the next five years with the most affected systems being prioritised and treated first. Eventually all UCL systems will be protected by magnetic filtration.

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