Technical Corner: Corrosion of HVAC Units

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Corrosion is arguably one of the major reasons for expensive HVAC replacement. It affects all HVAC systems regardless of geographical location, but tends to be even more of a factor for HVAC units located along the seacoast.

Corrosion takes place often unnoticed by the user until it is too late. Examples are many. Outside coils or condenser coils exposed to morning salt fog on coastlines often turn whitish. Over time, sometimes in as little as 18 months, these coils are corroded so severely that the coil fins literally fall off the internal copper tubing. This essentially makes the unit useless.

HVAC units around industrial type cities where sulfur oxides or nitrous oxides are more abundant also corrode from exposure to this type of atmosphere.

In seeking to retard the corrosion of outside condenser coils, many users elect to coat the coil fins, a normally very expensive procedure. Coating condenser fins in the past required the coil assembly to be freighted out to a vendor who specialized in applying an epoxy-based coating on the coils. After that, the coil was shipped back and had to be reinstalled. The initial cost of coating could run from several hundred to several thousands of dollars depending upon coil size. Coatings were often greater than 1 mil or 2 in thickness that increased operating costs of the unit due to the insulating effect of the coil coating.

Fortunately, there are more economic and easier ways to protect coils from corrosion. Weatherproof Coil Shield is a unique product developed by us and tested in an accelerated weathering chamber for 4,000 hours. In chambers such as this, the coil is subjected to 24 hours per day of alternating exposure to salt fog, industrial atmosphere such as NOx and Sox, and infrared light. Accelerated weathering chambers are used to determine the effects of long-term exposure to known corrosive factors in a short term.

Since Weatherproof Coil Shield can be applied by any maintenance person in ten to fifteen minutes, its use makes it ideal for corrosion proofing in-place any outside coil. The coil should be washed first to remove any dirt and residual corrosion, and then our product is sprayed onto the coil. Re-spraying is recommended to be done yearly.

Even interior cooling coils develop corrosion. For the most part, this is caused by aggressive coil cleaners which attack system metals. Condensate can also cause corrosion, as well as microbial buildup (fungus and bacteria) on the coil surfaces.

Besides plain corrosion, buildup of bacteria and fungi insulate the cooling or evaporator coil, making it less efficient.

Here, the solution is patented First Strike Micro Coat. As with Weatherproof Coil Shield, this product is easy to use, and lasts for a year or more.

First Strike not only handles corrosion, but help maintain efficiency, lowering monthly operating costs.

Here, the solution is patented First Strike Micro Coat. As with Weatherproof Coil Shield, this product is easy to use, and lasts for a year or more.

First Strike not only handles corrosion, but help maintain efficiency, lowering monthly operating costs.

Adding First Strike Microcoat to your preventive maintenance program is a wise decision, lowering monthly energy bill while helping to assist indoor air quality.

Please feel free to comment or share your experiences with us.

Lynn Burkhart is the founder and president of Controlled Release Technologies, Inc. located in Shelby, North Carolina. More information about the company, and its products, can be found at http://www.cleanac.com and by calling (800) 766-9057.

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