Get off to the right start with water treatment
Published: 02 March, 2017
With over half of the UK’s mains water supply classed as hard, effective treatment plays an important role in the maintenance regime of any water heating system. Chris Meir of Andrews Water Heaters, explains why investing in water treatment from installation makes financial sense in the long run, and discusses the solutions available.
In most commercial buildings, a consistent hot-water supply is a business-critical service. But with approximately 60% of the UK’s water supply graded as ‘hard water’* limescale can hamper the performance of water-heating equipment and put the hot-water supply at risk.
Limescale is caused by naturally occurring high levels of calcium and magnesium minerals in the water supply. It builds up more rapidly in hot water. When this happens, hot-water cylinders, water heaters and calorifiers are particularly at risk of impaired operation. In fact, deposits can begin forming as soon as a water heater is first installed.
When a water heater is supplied by hard water, limescale is deposited on the heat-exchanger surface, the internal surfaces of pipework and other system components, causing blockages, noise and potential equipment failure. At the same time, its accumulation on heat exchanger surfaces effectively insulates them, impairing the efficiency of the heater. According to British Standards (BS) 8558, tests have shown that limescale can reduce a heater’s efficiency by up to 30%.
For a commercial building manager or owner, limescale can lead to a number of problems, such as system downtime due to breakdown and unplanned repairs, additional expenditure for the replacement of components, and the associated costs of cleaning the water heater. If hard water is left untreated, it can cause harmful scale formation in as little as three weeks.
Although the quality of mains water supply is out of a building owner’s control, the occurrence of limescale in a hot-water system can be minimised by including an effective and regular water-treatment programme as part of any maintenance schedule right from the start.
Limescale is much more difficult and costly to eliminate from water heaters once it has physically formed, as the deposits need to be removed manually or by using a chemical descaler. Therefore, the first line of defence against limescale is to prevent its build-up in the first place. This can be achieved by installing a suitable Water Regulations Advisory Scheme (WRAS) approved water-treatment device that is connected at the point of supply.
One recommendation is to fit an electrolytic scale inhibitor, which will ensure an instant and constant solution for water treatment. Attached at the point of supply to the water heater, this device typically utilises the ion exchange process where the high levels of calcium and magnesium salts in the water are replaced with sodium salts, thereby softening the water. If this device is chosen for commercial buildings, a dedicated drinking water supply must be fed to the premises separately.
Another option is to fit a physical water conditioner, which uses a magnetic field to alter the physical characteristics of the minerals in the feed water supply. This particular method has proven to be effective in preventing limescale build-up in both storage and low-water-content heaters.
Unlike an electrolytic scale inhibiter, the feed water is not softened by this treatment, as the calcium and magnesium salts are not removed, nor is there any change to the chemical composition of the water itself. The benefits of using a magnetic device is a chemical-free, low running cost, permanent solution to reduce hard scale accumulation in the water system.
Upon commissioning, discuss your options with the installer, as using the wrong type of water treatment can cause equipment failure within a relatively short timescale. It is also crucial to consider maintenance access, the longevity of the treatment and the impact turbulent water flow may have on the performance of the device.
In addition to limescale, silt and sludge can also collect inside a water storage tank, impairing system performance and increasing maintenance costs. The sludge can be easily removed from the hot-water tank through periodic flushing of the system as part of a regular maintenance schedule. But to avoid its occurrence in the first place, it would be beneficial to fit a sediment filter at the point of entry for the incoming water supply.
We also suggest that the water quality is routinely checked (simple testing kits are available from companies such as Sentinel Commercial), as part of the maintenance programme. Regular testing can highlight any issues early on, and will indicate if treatment has stopped working, helping to save money in the long run. This approach is suggested by BSRIA, ICOM and leading commercial water-heating manufacturers.
Incorporating effective treatment into the installation of a water heater is essential. Combined with regular monitoring of water quality, building operators can maximise the performance and lifespan of a hot-water system. In turn, this will help reduce the cost of repairs for the owners, and minimise the impact of downtime on occupants and end users.
Chris Meir is sales director at Andrews Water Heaters.
* www.cambridge-water.co.uk/customers/water- hardness