Getting physical with hard water

Physical water conditioners can provide an effective way to address hard water issues, but it’s important to have an understanding about how they work and where best to locate them, as Darren Stacey, Head of Sales & Marketing at Lifescience Products, explains.

Darren Stacey, Head of Sales & Marketing at Lifescience

Technological advances in the water treatment industry have led to an increase in alternative technologies being used as replacements for more traditional types of hard water treatments. Physical water conditioners are now widely accepted by many as a low cost, easy to install and, in some cases, maintenance free alternative to chemical softening. But with so many different types of water conditioner available and still no official UK standard by which to judge them, how can plumbers be sure they’re making the right choices?

Cause and effect
Well, let’s start with the science. Hard water contains dissolved calcium minerals which are picked up as rainwater percolates through limestone bedrock. These hardness minerals can be brought back out of solution when the water is heated or subjected to a pressure drop. It’s the build-up of these deposits in the form of encrusted limescale that causes water heaters, valves and appliances to fail, reduces energy efficiency and provides a hiding place for bacteria such as Legionella.

Traditional base exchange softeners deal with this problem by replacing calcium with sodium, preventing the precipitation of limescale. When well maintained and serviced regularly, ‘salt’ softeners can provide an effective solution. However, they can be expensive, require regular dosing with salt and often there is a need to plumb a separate potable water supply to provide safe drinking water.

Physical water conditioners are unlike base exchange softeners in that they don’t need to remove the calcium from hard water to prevent limescale encrustation. They work by encouraging dissolved calcium to precipitate in suspension rather than encrusting surfaces. This means hardness minerals continue to be brought out of solution during a ‘scaling event’ but form onto seeds in the water, thus mitigating their effect on water heaters, valves, appliances and pipes.

Providing protection
Understanding the different mechanisms employed by physical water conditioners to encourage this process is the first step towards getting things right.

Many release zinc to act as the seed on to which limescale can form. The most effective tend to use galvanic corrosion to break down a sacrificial zinc anode over time. They are often the least expensive and easiest to install of the inline water conditioners and can be very effective. However, their lifespan could be limited to just a couple of years due to passivity as a result of scaling or the anode becoming exhausted. In the USA this has been demonstrated by a manufacturer now recommending their units are routinely cleaned with acids to reduce the effects of passivity.

For those looking for longer term protection, particularly those responsible for the ongoing maintenance of domestic water systems, an electronic/electro-magnetic water conditioner may be a more sustainable option.

There are a number of electronic water conditioners commonly available in the UK, with some being considerably more effective and reliable than others. Most are designed to be maintenance free and design life can be in excess of 25 years. A few will even descale existing plumbing installations.

By and large, electronic water conditioners act indirectly to encourage the formation of limescale in suspension.  They do this as part of a two stage process whereby a signal is transmitted into water to create pre-nucleation clusters that then act as seeds on to which scale is forced to precipitate when the water is heated or a pressure drop occurs.

Most types will only treat water locally to where they are installed, relying on a ‘memory’ effect to prevent scale encrustation further downstream. Some can treat static water but the effect is often very short lived so for these devices the closer together the two stages occur, the more effective the treatment is likely to be.

Other electronic water conditioners use radio wave technology to create pre-nucleation clusters. These waves can be continuously transmitted through the water, both upstream and downstream, irrespective of flow. Providing there is continuity of signal they’ll provide constant treatment to all of the water all of the time, without any reliance on the memory effect.

This type of electronic conditioner allows for continuous treatment of sites where long periods of low or intermittent usage are common such as schools, universities and large scale multi-occupancy buildings. But continuous treatment is predicated on these units being correctly installed downstream of pumps and storage tanks, which could cause signal degradation.

For heat exchangers with pumps on the cold water inlet and some modular type water heaters, it’s often more effective to treat the outlet side of the heater, using a back signal to protect the heat exchanger whilst also continuously treating the stored hot water in a buffer vessel.

Hot water secondary returns should be treated by locating a supplementary unit downstream of the return pump to ensure continuous treatment of the returning hot water as it re-enters the water heater. Similarly, for irrigation systems and re-circulating systems like swimming pools, locating a unit after the pump as close to the ‘scaling event’ as possible will provide continuous protection.

Better understanding
So, while it’s true to say that some electronic water conditioners can provide greater flexibility through continuous treatment, understanding where best to locate them is still crucial. Such understanding can only really be derived from those manufacturers who provide training opportunities for installers and specifiers.

Traditionally, access to training has been limited to a handful of seminars offered to mechanical and public health engineers. The best of these have formal accreditations from recognized industry bodies including CIBSE and CIPHE. They can provide an invaluable insight for those with the time to attend but often fail to reach smaller contractors and individual installers who cannot afford time away from site.

For those who only have a few minutes on site or in between call outs, access to online content is crucial. But whilst there’s no shortage of material online, cutting through to find reliable information isn’t always easy.

Our solution has been to launch the free-to-access Lifescience Academy – home to a new e-learning module, literature, technical information and installation guides.  The resources can be accessed whenever they’re needed and provide all of the information a plumber needs to install with confidence. To find out more about our e-learning module and our range of electronic water conditioners, please visit the website below.

www.lifescienceacademy.co.uk

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