Why Should Cooling Coils Be Replaced?

Why Should Cooling Coils Be Replaced?

In an ideal world, most cooling coils should last for at least twenty years. Lack of proper maintenance, inappropriate applications, corrosion, and subpar modern-day construction all reduce cooling coil life expectancy. The following are the three most common reasons for premature cooling coil replacement:

1. Increased air resistance due to coil surface plugging.

What is the source of this plugging?

There is an increase in dirt and airborne material lodged deep within the coil core that cannot be removed using a standard air side cleaning process. This situation is caused by improper filter replacement and a lack of annual coil cleaning. Because of the insulating effect of the material inside the coil core and the resulting reduced air flow, a plugged coil reduces overall heat transfer.

2. Significant damage from a freeze event.

Why is there freeze damage when the majority of cooling coils are inactive during the winter heating season? Many coil manufacturers have included circuitry in their coil designs that prevents full drainage. Drain locations are frequently located above some of the tubes and circuits required to fully drain the coil. If a coil has extensive freeze damage, it is nearly impossible to find all of the leaks. Even if the initial leaks are found, the tubes have been compromised and may fail again in the future. This is due to the wall thinning caused by the increased pressure caused by the freeze event.

3. Corrosion

External corrosion can occur where the tubes and fins meet in a salty environment. This will appear as a white ring around each tube in the coil. This means that you're losing tube and fin contact, which reduces performance. Furthermore, the white corrosive byproduct will fill the coil's core, drastically reducing air flow.

There are numerous other types of corrosion, both on the air side and in the water/refrigerant side tubes. Raw, untreated water, which contains minerals and byproducts that may corrode copper, is one form of importance on the water side. Hydrogen sulfides produced in sewer treatment plant applications are another source of corrosion on the air side.

It is critical to note that a competent coil specialist should review the issues that resulted in the premature coil replacement and, if possible, redesign a coil to increase longevity. Modifications can also be made to increase capacity, decrease air and fluid pressure drops, and provide a much better coil design.

Cooling coils are constantly replaced, and approximately 95% of them never reach their full life expectancy. It is critical to comprehend why this occurs. It is equally important not to confuse one problem with another.