HVAC, Building Performance: Preventing Coil Corrosion

Hurricane conditions may cause more corrosive damage to HVAC systems than other factors that typically cause corrosion. The problem is that corrosion problems may not be apparent immediately, according to an article in ACHRNEWS.

However, as we gear up for the cooling season, these problems may become more evident to people living in areas impacted by the previous season’s hurricanes like Hurricane Sandy. Sandy impacted the east coast as it became the most destructive tropical storm of the Atlantic hurricane season.

While the salt air/water of heavy coastal rains can impact corrosion, so can other conditions including environmental pollution from household cleaning products and pesticides, and poor water quality.

Coil corrosion will either present itself in the form of pitting or formicary deterioration, according to Reliable Plant.

Pitting is often caused by exposure to fluoride, found in most water supplies, or by exposure to chloride, found in snow melt, detergents and other products. Chloride or fluoride ions transfer to the coils via condensate. The ions attack the metal, form pits that become pinholes, and cause the coils to leak refrigerant.

Corrosion through formicary occurs because of exposure to acetic or formic acids. Both types of acids are found in household cleaning products and other common household solutions. Most often formicary corrosion causes tunnels to form within the tubing. Those tunnels also turn into pinholes, and, again, the end result is a refrigerant leak.

The best way for a building owner to prevent coil corrosion is to apply a protective coating to the coil.

Coating types include polyurethanes, epoxies, fluoropolymers and silanes. Each coating type has its own distinct advantages and disadvantages. Read more about the pros and cons of each coating type in “HVAC Coil Corrosion: Should You Be Concerned?“.

Whether you apply coatings or not, another good way to fight coil corrosion is with regular cleaning, at least twice each year. A thorough cleaning removes deposits to prevent corrosion, and it also improves the system’s efficiency. Water is sometimes all you need to clean the coils, but coil cleaning solutions will remove any build-up more effectively.

Goodway’s CoilShine is a non-acidic detergent formulated to clean dirty evaporator and condensor coils. It’s nontoxic and has a mild, pleasant odor. The cleaner also features an expanding and self-advancing foam formula that penetrates the coils and removes build-up. It’s also biodegradable so it can be safely flushed down drains.

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