WET News

18 WET NEWS JUNE 2014 Water industry contractors are often called upon to provide effective and reliable lime- scale prevention systems. However, sourcing solutions that meet today's high environ- mental and economic demands can be difficult. Sentinel's Ian Barnes reports. The challenge: Treating lime- scale effectively and efficiently INSIGHT WATER TREATMENT MAIN:Scale building up on a heat exchanger. Just 1.6mm of limescale build-up can increase a heating system's fuel requirements INSET: Water hardness is mainly concentrated in the south and east of England T here is not a water indus- try contractor in the country who is not aware of limescale – a by-product of heating hard water – and at least some of its associated problems. Indeed, about 65% of the population in England is pro- vided with hard municipal water (defined as water of more than 200ppm Total Hardness – mostly soluble calcium bicar- bonate), and as many hard water areas overlap with regions where industry and commerce is concentrated, limescale affects more than two-thirds of commercial and industrial operations in main- land England. As anyone who has boiled a kettle or taken a shower in a hard water area will know, limescale accrues quickly on appliances and sanitary ware. For domestic dwellings, this may be considered a bit of a nuisance, however for large commercial premises (which o…en have hundreds or thou- sands of appliances), it can be a very costly problem in terms of cleaning, downtime and asset replacement. However, far more sinister – and potentially costly – are the 'unseen' effects of lime- scale on untreated heating sys- tems. Insoluble calcium car- bonate begins to precipitate at around 35-40oC and exhibits inverse solubility as tempera- tures rise. Consequently, limescale deposits accumulate quickly in untreated heating systems, particularly on heat transfer surfaces such as heat exchang- ers and pipes. Hot water systems, also known as 'once through' water heaters, heat large amounts of fresh water, so are especially susceptible to limescale accumulation. British Water states that just 1.6mm of limescale build-up can increase a heating system's fuel requirement by as much as 12%. Limescale acts as insula- tion, reducing the efficiency of heat transfer surfaces. The result is that boilers run hotter, for longer, consuming more energy. In pipework, limescale deposits reduce bore size and impair water flow, increasing pressure on pumps. As a consequence, energy consumption, system noise, and stress on pipework increase. Furthermore, lime- scale will accumulate readily in calorifiers, inhibiting operation. Softeners Conversely, effective water treatment will help equipment operate efficiently for longer, keeping energy, maintenance and repair bills (not to mention THE CONCEPT • Uses UK Building Regulations Compliance Guide recommended electrolytic technology • Conditions water by delivering a very low level of stable zinc into system water • Zinc anode changes deposit-forming Calcite into non-deposit forming Aragonite • Practically eliminates limescale formation in hot water systems THE VERDICT "We have been highly delighted with this scale prevention product. Since installation three years ago, the KalGuard has performed very well and is virtually maintenance free." Mark Howard, British Gas Business "We have been very pleased with KalGuard technology and its ability to keep our water heater system operating efficiently. York water is known to be very hard and limescale prevention is a challenge which KalGuard has helped the school overcome." • carbon emissions) as low as possible. But which technologies are proven to be effective? Chemi- cal inhibitors, polyphosphates, electrolytic devices, and water so…eners are recommended by the Compliance Guide to Part L UK Building Regulations as suitable provisions for reduc- ing the rate of limescale accumulation. Of these solutions, chemical inhibitors and polyphosphates are not widely used, as the for- mer are generally unsuitable for addition to potable water, while maintaining an effective concentration of the latter proves very difficult in com- mercial systems. Both methods also entail the usual problems associated with chemical stocking, stor- age and handling. Salt-based, ion exchange water so…eners have been a popular choice for decades. However, such systems add high levels of sodium to the water, waste valuable water for regeneration, and require rou- tine maintenance and regular salt-top ups. n NEED TO KNOW • Maintains energy efficiency by reducing limescale accumulation • Improves water flow by keeping pipes clear of scale • Does not waste water and requires no salt, unlike salt-based water softeners • Requires minimal maintenance • One device can treat a whole system "However, far more sinister – and potentially costly – are the 'unseen' effects of limescale on untreated heating systems. Insolu- ble calcium car- bonate begins to precipitate at around 35-40oC and exhibits inverse solubility as temperatures rise." Ian Barnes SHARE YOUR OPINION... yoursaywn@fav-house.com JUNE 2014 WET NEWS 19 An alternative approach to enhancing capacity and ensuring compliance during treatment plant upgrades. A solution: Time to think zinc A n effective solution that of- fers better economical and environmental credentials is KalGuard, which conditions water by delivering a very low level of stable zinc into it, via an electrolytic process that uses a zinc anode and a copper cathode. The zinc holds much of the naturally occurring calcium car- bonate in solution, minimising the formation of crystals, and forces any naturally occurring calcium carbonate crystals that do precipitate to form as so• non-deposit-forming Aragonite rather than into hard, deposit- forming Calcite, helping pipe- work stay limescale free. Independent tests carried out at Cranfield University have proven the product's ability to drastically reduce limescale. Furthermore, it is successfully deployed in thousands of com- mercial operations throughout the country, including many major hotel and restaurant chains. A significant cost benefit of KalGuard is that it can be installed on a rising main before the water storage tanks and booster sets (since the treatment does not decay on standing or agitation), so limescale control can be provided wherever the water is delivered, and both hot and cold flows can be treated by a single unit. Also, it is WRAS- approved, and no separate drinking water supply is required. Expenditure This ability to be installed on the incoming riser additionally enables capital expenditure reduction when compared to installing the technology on a larger distribution pipe – a not insignificant cost saving. For example, if a location has a 108mm distribution pipe size and a 54mm rising main appli- cation feeding a water tank, these savings will be around 65% compared to a standard installation. The ROI for the product is typically less than 12 months. A salt-based regenerating water so•ener requires regular expenditure on salt and the water used in regeneration, which on a 42mm water system could represent a cost of more than £4,200 per year. Neither salt nor water are required with KalGuard. Environ- mental concerns are eased too, since water is no longer wasted, and the carbon footprint of salt can be as large as one tonne of carbon dioxide for every four tonnes of salt used. Notable features that make for an easy and fast installation process – it can be installed in one day – include an intuitive user interface, organic LED dis- play, a dedicated terminal access bay, convenient wall fixing points, a wall mounting template and tamper proof screws. Day-to-day maintenance requirements are also signifi- cantly lower than for salt-based water so•eners, indeed they are negligible, since there is no need for regular water testing, moving bags of salt (which may also be a Health & Safety issue), or resin replacement. In contrast, KalGuard's filter simply needs to be flushed twice a year, while the zinc anode has a lifespan of around eight to ten years, a•er which time the usea- ble zinc may be depleted, and the anode may need to be replaced to continue optimum functionality. n Ian Barnes is head of Sentinel Commercial. www.sentinelprotects.com Zinc anode based driven electrolytic technology changes deposit-forming calcite into non deposit- forming aragonite

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