Discovering that your HVAC system has developed coil corrosion will probably come as a surprise, and not a pleasant one. Corrosion in an HVAC system’s evaporator coil signals either a major repair or a system replacement. Heat pumps and air conditioners use an indoor evaporator coil and an outdoor condensing coil.
Causes of Corrosion
In recent years, HVAC professionals have found corroded coils in homes primarily in the south where builders unknowingly turned to drywall imported from China. The tainted drywall emitted sulfurous gases that reacted with the copper in evaporator coils and home wiring. The evaporator coils developed pits and subsequent corrosion.
Copper corrosion also occurs when it’s exposed to acetic or formic acids found in household products like adhesives, cleaning solvents, paint and plywood. It shows up as blue or black deposits on the coils. Another common source is new carpeting, fabrics, or detergents. Regardless of cause, pinhole leaks form and eventually pressurized refrigerant leaks out, making the system inoperable.
Prevention
Avoiding the products that cause coil corrosion not only protects your evaporator coil, it also reduces risks to your own health. Try as much as possible to use only building and remodeling materials that are low in volatile organic compounds (VOCs).
Annual cleaning also prevents coil damage. Use a pH balanced cleaner and a soft cloth. If you notice any damage, contact your HVAC technician immediately. The outdoor condenser coil may also corrode if too much dust builds on it over time. Hose it off gently a few times during the cooling season.
Repair or Replace
Once corrosion has created holes, it’s almost impossible to repair them. The evaporator coil will have to be replaced. The replacement coil must match the outdoor coil in capacity and refrigerant type. If finding a matching coil is not possible, you’ll have to replace the entire system.
Coil corrosion is a serious threat to HVAC systems and although it’s fairly rare, its consequences are serious. For more information about avoiding it, contact Ace Hardware Home Services, providing trusted HVAC services for Dayton-area homeowners.
Our goal is to help educate our customers in Dayton, Ohio about energy and home comfort issues (specific to HVAC systems).
