How Corrosion Impacts Commercial HVAC Systems (And How to Prevent It)

Corrosion is one of the most common — and costly — threats to commercial HVAC systems. HVAC coil corrosion often develops silently, reducing efficiency long before a system completely breaks down.

For facilities in humid climates, coastal regions, or industrial environments, corrosion can dramatically shorten the lifespan of evaporator and condenser coils. Left unchecked, a corroded HVAC coil can lead to refrigerant leaks, rising energy costs, and unexpected downtime.

Understanding what causes corrosion — and how to prevent it — can save thousands in repair and replacement costs.

What Is HVAC Coil Corrosion?

HVAC coil corrosion occurs when the metal surfaces of evaporator or condenser coils begin to deteriorate due to chemical reactions with moisture, airborne contaminants, or salt exposure.

Commercial systems commonly use copper tubing and aluminum fins. Both materials are vulnerable:

• Copper coil corrosion often appears as pitting or microscopic pinhole leaks.

• Aluminum coil corrosion typically shows as oxidation and fin degradation.

Over time, corrosion weakens the structural integrity of the coil and reduces heat transfer efficiency — forcing your system to work harder to deliver the same performance.

The Leading Causes of Commercial HVAC Coil Corrosion

Salt Air & Coastal HVAC Corrosion

Facilities near the ocean face accelerated deterioration due to salt-laden air. Coastal HVAC corrosion occurs when salt particles settle on coils and attract moisture, triggering rapid oxidation.

Rooftop units are especially vulnerable. In coastal environments, unprotected coils can experience severe damage in just a few years.

Industrial & Chemical Exposure

Manufacturing plants, processing facilities, and even certain commercial buildings release airborne chemicals that contribute to HVAC coil corrosion. Cleaning agents, combustion byproducts, and industrial pollutants can all attack coil surfaces.

These contaminants are a major cause of copper coil corrosion, particularly formicary corrosion — a type of internal pitting that creates small refrigerant leaks.

High Humidity & Condensation

Moisture is a catalyst for corrosion. In humid climates or buildings with poor drainage, standing water and constant condensation accelerate both copper coil corrosion and aluminum coil corrosion.

Without regular inspection, these issues compound quickly.

How HVAC Coil Corrosion Impacts System Performance

Corrosion doesn’t just damage metal — it impacts performance.

When a coil begins to deteriorate:

• Heat transfer efficiency drops

• Energy consumption increases

• Refrigerant leaks become more likely

• Airflow becomes restricted

• System lifespan shortens

Common signs of a corroded HVAC coil include:

• Visible rust or pitting

• Oily residue (a sign of refrigerant leaks)

• Uneven cooling throughout the building

• Ice buildup on the coil

Ignoring early symptoms of HVAC coil corrosion often leads to complete coil failure.

Copper Coil Corrosion vs. Aluminum Coil Corrosion

Understanding the difference between materials matters when evaluating repair or replacement options.

Copper Coil Corrosion

Copper is durable but highly susceptible to formicary corrosion. This type of copper coil corrosion creates microscopic tunnels in the tubing, leading to hard-to-detect refrigerant leaks.

Once pinhole leaks begin, repair is often temporary.

Aluminum Coil Corrosion

Aluminum coil corrosion typically appears as oxidation on the fin surfaces. Over time, aluminum fins can weaken, reducing structural stability and airflow efficiency.

In harsh environments, both materials require additional protection.

How to Prevent HVAC Coil Corrosion

While corrosion cannot always be eliminated, it can be significantly slowed.

Protective Coil Coatings

Protective coatings are one of the most effective defenses against HVAC coil corrosion, especially in coastal and industrial environments.

Options include:

• Epoxy coatings

• Phenolic coatings

• Electrofin coatings

For facilities exposed to salt air, investing in protective coatings can dramatically reduce the effects of coastal HVAC corrosion.

Routine Inspection & Maintenance

Preventive maintenance is critical. Annual inspections should include:

• Coil cleaning

• Drain pan checks

• Airflow verification

• Corrosion assessment

Early detection of copper coil corrosion or aluminum coil corrosion allows facilities to plan strategically instead of reacting to failure.

When to Repair vs. Replace a Corroded HVAC Coil

Surface-level corrosion may be manageable with cleaning or coating. However, if leaks develop or structural integrity is compromised, replacement becomes the most cost-effective solution.

In many cases, replacing just the coil — rather than the entire unit — restores system performance at a fraction of full equipment replacement costs.

Custom-fabricated coils also allow facilities to upgrade materials or add protective coatings to better resist future HVAC coil corrosion.

Why Custom Replacement Coils Make a Difference

OEM coils may not always be optimized for harsh environments. A custom replacement coil provides:

• Exact dimensional fit

• Material upgrades

• Enhanced protective coatings

• Faster turnaround

For facilities dealing with recurring coastal HVAC corrosion or industrial exposure, upgrading during replacement can extend system lifespan significantly.

Take Action Before Corrosion Leads to Failure

Corrosion is predictable — and preventable with the right strategy.

If your commercial HVAC system is showing signs of HVAC coil corrosion, early evaluation can prevent costly downtime and refrigerant loss.

At Re-Coil Solutions, we specialize in custom replacement coils designed for commercial and industrial environments. Whether you’re dealing with copper coil corrosion, aluminum coil corrosion, or severe coastal HVAC corrosion, our team can measure, fabricate, and replace coils built to withstand your specific conditions.

Don’t wait for failure. Evaluate corrosion early — and protect your system investment.