HVAC Coil Corrosion: Should You Be Concerned?

Coil Cleaning

Approximately 40% of industrial equipment failures are caused by corrosion, according to CED Engineering. Corrosion of HVAC coils can be a costly problem, resulting in replacing the coils or entire systems.

Coil corrosion is prevalent in facilities situated in more corrosive environments such as near salt water or industrial sites. A higher amount of corrosion can also be found in areas surrounding pools, laundries, water treatment plants, sewers, and areas with high traffic.


Generally, corrosion manifests itself either as pitting or formicary deterioration. After an installation, corrosion could develop as soon as a few weeks or it could take up to four years.  


Pitting corrosion is most often caused by exposure to fluoride or chloride. 


Municipal water supplies contain fluoride, while chloride is found in various products, including snowmelt, detergents, cleaners, carpeting, and fabrics. Pitting occurs when chloride or fluoride ions reach a metal via a condensate. As the ions attack the metal, pinholes form, causing the coils to leak refrigerant.

Formicary Corrosion

Formicary corrosion is typically caused by exposure to acetic or formic acids. 


Acids are found in many household products, such as cleaning solvents, insulation, adhesives, paints, plywood, and many others. As a result of formicary corrosion, pinholes tend to form in the coils, leading to refrigerant leaks. The first sign of this corrosion may not be immediately apparent, and in some cases, deposits are black or blue-gray in color.

coil cleaning


Close suggestions
Search Suggestions
Recommended products
Suggested terms