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Chillers & Closed Loop Systems

Chemical Water Treatment for Chillers & Closed Loop Systems

This post will review the basics of chemical water treatment for chillers and closed loop applications. It will also consider how to increase efficiency in chillers by using chemical water treatment. For more information on chemical water treatment in other types of equipment, revisit our Education Center.

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An industrial chiller is used as an HVAC component to cool a building or, in industrial applications, to cool equipment. In these processes, water is maintained at specific temperatures for chiller efficiency, and is treated to maintain specific levels of purity, oxygen, PH, and other factors. Because water has naturally occurring impurities, treatment for corrosive components is critical for use in any cooling application. The reason water is treated for corrosion is to utilize all of the beneficial characteristics of water, while counterbalancing the negative effects of the impurities in the water. Corrosion-causing impurities can lead to early failures of capital equipment and piping, loss of cooling efficiency and negative impacts to asset production.

Chillers may operate as closed loop systems. Closed loop systems transfer heat through circulating water for cooling, heating and various industry processes. Other chillers may operate as feed-water systems, though these require a constant water source, making them less appropriate for use in drier climates. A closed loop system operates more conservatively, as well as minimizing the risk of environmental contamination. Manufacturers, hospitals, and industrial facilities typically rely upon closed loop systems. 

Impacts of Scale Forming Deposits & Bacteria Growth

Regardless of the chiller system type, in the interest of water conservation, it is paramount that water is treated chemically so the chiller can operate in the most efficient manner possible. Via either vapor-compression or absorption, heat is removed from the liquid flowing through the industrial chiller. In order for this process to remain efficient, the heat-transfer surfaces of the chiller must remain free of damaging impurities. Corrosion, mineral scale, and bacteria are the greatest threats to the system. Treatment of the water with corrosion inhibitors, chemicals that resist scale formation, and non-oxidizing biocides is required.

Naturally occurring impurities in water may lead to scale or sludge deposits where water circulates. As impurities become more concentrated, there is a growing increase for the potential of corrosive accumulation. This begins to obstruct heat transfer which leads to higher energy costs, which can lead to loss of equipment efficiency and early failure. Treating the water helps to control the negative effects it can have on the chiller.

Importance of Preventing Legionella

Recirculating water is an excellent environment for biological growth such as algae, bacteria, slime, and water-borne pathogens such as Legionella. These are micro-organisms in the cooling system. These bacteria usually form a biofilm on the surfaces that have contact with the circulating water. The biofilm can act as a thermos insulator which can also decrease heat transfer efficiencies.


If water-borne pathogens are present in the water, such as Legionella, this can cause serious health and safety problems for operators. Legionella can travel in droplets during normal use of HVAC system components. When caught into an airstream or circulated into a building, these droplets can become a source of severely infectious disease. Use of a chemical water treatment plan that considers biocides helps to prevent growth of water-borne pathogens such as Legionella.

Chemical Water Treatment Plan Optimization

Typically, when a chemical water treatment plan is newly optimized, operators will see efficiency improvements quickly. An optimized chemical water treatment plan clears existing buildup, prevents bacteria and water-borne pathogen growth, and allows for optimal unit operation. These benefits will save energy expenses and improve asset performance.


Conversely, if left untreated or under-treated, continual build-up and bacteria growth will result in equipment failure or possible spread of illness. This will not only be costly, but also poses a direct safety hazard to the public. Bacteria, algae, mold, and fungi can contaminate chillers and closed-loop water supplies, and require the use of chemical water treatment to mitigate and prevent accumulation and growth.

There are multiple ways to apply chemical to a cooling application. Historically, chemical was often delivered to a treatment room pre-mixed in large 55 gallon drums. However, this created great risk of chemical exposure to technicians, high logistics costs in transporting full drums, required excessive floor space for storage, and necessitates drum cleaning and careful removal when chemicals need restocking.


Today, water treatment is now more safe and efficient thanks to ultra concentrated liquid chemical water treatment options. Similarly to the revolution that the laundry detergent industry faced, ultra concentrated water treatment options allow for smaller containers, less water wasted in pre-mixing, and more efficient use of chemical.

To learn more about LiquiLogic ultra concentrated liquid chemical water treatment products for chiller and closed loop applications, visit the Products page.



#watertreatment #legionella #biofouling #chillers #customsolutions


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