An Epidemic Hiding in Plain Sight
Here's something the industry doesn't advertise: evaporator coil failures from corrosion are happening thousands of times per day across North America.
This isn't rare. This isn't unusual. This is an epidemic.
Manufacturers process warranty claims for corroded coils constantly—it's one of their largest cost centers. The engineering reality is simple: modern coil designs create the perfect conditions for electrochemical corrosion, and no amount of quality control can change basic chemistry.
The coils aren't defective. They're doing exactly what physics dictates they'll do when you put dissimilar metals in contact with an electrolyte. They're corroding.
Why Modern Coils Are Vulnerable
Modern evaporator coils are engineering marvels of efficiency. They're also electrochemical time bombs. Here's why:
To maximize heat transfer while minimizing cost, manufacturers build coils from:
- Aluminum tubes (excellent heat transfer, lightweight, inexpensive)
- Aluminum fins (maximize surface area)
- Copper connections (required for refrigerant line brazing)
The problem? When copper and aluminum are in contact in the presence of an electrolyte (like condensate water), they form a galvanic cell—essentially, a battery.
From the Carrier/Bryant CAAMP Installation Manual:
"CAUTION: Take precautions to ensure Aluminum tubes do not come in direct contact or allow for condensate run off with a dissimilar metal. Dissimilar metals can cause galvanic corrosion and possible premature failure."
Current flows. Electrons move. And the aluminum—being more "active" electrochemically—corrodes preferentially to protect the more "noble" copper.
Your coil is literally eating itself at every copper-to-aluminum joint, every hour it operates.
How Thin Is the Line Between Working and Leaking?
The Carrier 37MHRAQ mini-split specification sheet lists the evaporator tube wall thickness: 0.24mm
That's 0.00945 inches. Less than 1/100th of an inch.
That's all that separates your refrigerant from your living room. That's all that stands between "comfortable" and "catastrophic." And galvanic corrosion is working on that barrier every day, every condensation cycle, every summer.
The Chemistry of Cooling
Your evaporator coil works by being cold—cold enough that water vapor in your home's air condenses onto its surface, just like water beading on a cold glass of iced tea. This is how your AC dehumidifies: it literally wrings moisture out of the air.
That condensate water then drains away through the condensate line.
Simple, right?
Here's the problem: that condensate isn't pure distilled water. It contains:
- Dissolved carbon dioxide from the air (making it slightly acidic)
- Dissolved oxygen (enabling oxidation reactions)
- Dust, pollen, and particulates from the air
- Volatile organic compounds from household products
- In some cases, acidic compounds that cause "formicary corrosion"
This condensate coats your coil surfaces constantly during operation. And it doesn't just sit there—it creates an active electrochemical environment.
Multiple Corrosion Threats
Your evaporator coil faces multiple corrosion threats simultaneously:
- Galvanic Corrosion: When copper and aluminum meet in the presence of moisture, an electrochemical reaction rapidly destroys the aluminum.
- Formicary Corrosion: The most insidious type—microscopic tunnels that branch through the metal like ant colonies. Organic acids from VOCs create branching tunnels inside copper tubes.
- Acidic Attack: VOCs from cleaning products and building materials form acids that eat through metal surfaces.
- Environmental Stress: Humidity, temperature cycles, and intermittent wet/dry conditions accelerate all these processes.
The Solution: Proven Protection Technology
CoilShield uses cathodic protection—technology proven in marine and pipeline applications for 200 years—to prevent all forms of coil corrosion.
By making your coil the cathode in an electrochemical cell, corrosion becomes thermodynamically impossible. The reaction simply cannot proceed.
Prevention beats replacement. Every single time.
Don't wait for your coil to fail. Protect it now with CoilShield.
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