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Water heating is an essential investment in any residential or commercial asset. However, lime scale buildup can often accumulate within heating equipment and significantly reduce boiler effectiveness, impede the quality of heat transfer and increase energy consumption, ultimately leading to equipment failure.

What causes lime buildup?

Water naturally contains dissolved minerals such as calcium bicarbonate, silica, iron and phosphate, to name a few. These trace elements are essential to human health, but harmful to the equipment producing hot water. Under the effect of heat, minerals tend to rush to the walls and form an insulating wall on the surfaces and electrical elements.

While new water heating equipment offers maximum efficiency, its value reduces considerably as soon as the lime scale and other particles fuse and cook under the heat to produce a hard crust. Glued to the walls, buildup will increasingly block the transfer of heat. Meanwhile, the extra heat that is stored and not transferred into water weakens the resistance of steel, copper and other materials.

Scale buildup in a heat exchanger is a serious matter because lime will reduce the rate of heat transfer. At The Master Group, we noticed that a reduction in efficiency is usually the first consequence. Such scale will greatly reduce the life of the exchanger, while the temperature of the combustion products will dramatically increase.

When installing gas appliances it is very important to anticipate temperature increases in the venting system. The temperature of an exhaust system above an acceptable number could deform the piping, causing damage and injury. Yet, some contractors still prefer offering lower prices and cheaper material in order to remain competitive. The possible consequences of such negligence shouldn’t be underestimated.

Also, take note of the following three elements involved in lime buildup: more than 120 milligrams per litre as CaCO3 or 7 grains, heat and high pH levels. In hard water, it will form twice the scale to 65.5 Celsius (C) than at 54.4 C, and three times at 76.6 C.

Preventing lime scale buildup

For a continuous water heater (tankless water heater), cleaning a heat exchanger after one year of use will ensure an adequate efficiency rate and is essential to determine the sequence of cleaning needs, depending on the degree of water hardness.

Exchangers can be cleaned using slightly warmed vinegar and a pump system specially designed for this purpose—unsusceptible to the vinegar’s acid. At The Master Group, we use the Bucket Descaler as a viable option in this case. 

A water softener can also be installed, as well as an anti-scale control system. Conventional heater tanks should also be emptied on a regular basis. As for boilers with a heat exchanger and a very small amount of water, it is essential to first treat water with a water inhibitor. This treatment slows and/or stops the chemical reaction that causes lime formation.

Connect with Andre Massé, heating products director at The Master Group, for more information on lime scale reduction and prevention. 

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