How to Prevent HVAC Coil CorrosionYou have coils in two locations in your air conditioner. One set is called the evaporator coils, and they are located in the inside unit of your A/C. The other set is found in the condenser in the outdoor unit. Both sets circulate refrigerant and transfer heat. They are crucial to the cooling process.

Dirty Coils

Coils get dirty over time. They can develop a thin coating of dirt or dust, grease, bacteria, cigarette smoke or corrosion, all of which insulate the coils and prevent them from doing their job. Outdoor coils may be particularly vulnerable, as they are exposed to not just dirt, but grass clippings and even dog urine.

A good cleaning will help prevent problems, but if your coils have corrosion, other factors may be involved. Read on for information on preventing coil corrosion.

What Causes Coil Corrosion?

Corrosion becomes obvious when coils exhibit pitting. There is also another type of corrosion called formicary deterioration, which cannot be seen.

Corrosion is caused by salt-laden air, high relative humidity and airborne molecular contaminants. Fluoride in the water supply may also cause pitting.

Formicary corrosion is caused by acetic or formic acids, which are present in household cleaners, paints, glues, plywood and other things. It may look like a dark bluish gray or black deposit, but it might also not be seen. The corrosion creates tunnels in tubing, which creates pinholes in the coils and can lead to a refrigerant leak. Refrigerant leaks diminish the system’s capacity to cool.

Preventing Coil Corrosion

To prevent coil corrosion, manufacturers have begun to coat metals prior to production. Several types of aftermarket coatings are also available, which your HVAC tech can apply to your coils after cleaning. The various types of coatings all have advantages and disadvantages, so it’s best to rely on the advice of your HVAC expert rather than trying to coat your coils yourself.

One of the best preventatives is just to schedule coil cleaning twice a year.

To learn more about preventing coil corrosion, contact Detmer and Sons. We have served Dayton since 1978.

Our goal is to help educate our customers in Dayton, Ohio about energy and home comfort issues (specific to HVAC systems). 

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