Cooling towers on commercial HVAC systems are designed to use the principle of evaporation to get rid of the heat generated by the compressor as well as to provide cooling of the compressor refrigerant.
Understanding how a cooling tower system operates will provide insight into some of the challenges of cooling tower water treatment basics. These challenges include the increase in the concentration of contaminated water in the system and the resulting problems with ongoing efficiency and effectiveness over time.
Circulation
As part of cooling tower water treatment basics, it is important to realize that the water in the system is continually circulated through the chiller tubes in the HVAC system. The longer the water stays in the system, the higher the levels of both organic and inorganic contaminants in the water.
When the cool, contaminated water comes into contact with the warm to hot heat transfer components, these contaminants form a layer on the surface. They will literally cover the entire surface, building a thicker and thicker while also leading to increased risk of corrosion in the system.
The organic contaminants such as bacteria and biofilm are problematic, but scale and corrosion are the most destructive.
Scale and Corrosion
Anyone who has hard water and has cut into a pipe knows the problem with scale, or the deposits of minerals and inorganic salts on the surfaces exposed to water. The heat transfer areas, as well as tubes themselves, can be coated.
The thicker the coating gets, the less efficient the cooling system will work. This causes a perfect environment for more deposits, less water circulation and a continual cycle of the buildup of scale.
Traditionally acids were used to flush through the system to remove scale. This, in turn, leads to an increased risk of corrosion, which is just as problematic. White rust, another issue that can occur with water softening systems using salt, is a leading cause of concern for corrosion.
Getting rid of the risk of scale and corrosion is one of the most important cooling tower water treatment basics. Systems that use specialized ionizers, often copper and silver combinations can be effective in reducing organic contamination are highly effective. Adding a water treatment system that uses an electronic water descaler and a water descaling system without the use of harsh chemicals is the best possible option in cooling tower maintenance for any HVAC system.
