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Your HVAC Evaporator Coil Could Use Some TLC This Spring

When it comes to taking care of your HVAC system, chances are you already have the basics down pat. You know you should change your air filter every month and keep the vents free of dust and debris. But being a good steward to your HVAC system involves more than just taking care of the stuff you see.

There's a lot about your HVAC system that you normally don't see in action. The evaporator coil, located within the indoor cabinet of your central HVAC system, is a hidden component with a huge role to play in keeping your system efficient and cost effective.

The Evaporator Coil, in a Nutshell

The evaporator coil is a principal tool in the air conditioning process, as it helps facilitate the removal of heat from the indoor spaces within your home and expel it outdoors. Air flows in between the fins of the evaporator coil, allowing the refrigerant inside of the coil to gather the latent heat and transfer it elsewhere.

In a central HVAC system, the evaporator coil sits on top of the air handler. Once the sheet metal plenum surrounding it is opened, you'll notice that the environment it lives in is a dark and constantly damp one. It just so happens that mold and mildew thrive in dark, damp areas, especially places that are completely closed off to sunlight and kept with high levels of moisture.

When the plenum and evaporator coil become covered in mold, it reduces the unit's cooling effectiveness by a significant degree and causes it to waste more energy. The end result is further unnecessary wear and tear on other system components, an expensive energy bill due and a system that could potentially leave you sweltering when you least expect it. A clogged coil can even lead to severe frost on the coils themselves.

Cleaning the Coil

The first order of business involves cleaning the coil itself. Although there are several ways to do it, the simplest and least damaging involves the use of a no-rinse foaming cleaner. All you'll have to do is spray the foam onto the coil and possibly other areas affected by the mold. The cleaner will break down the mold and drain away on its own.

If you don't have mold but do have dust accumulating on the coils, you can use a shop vacuum with a soft brush attachment to gently vacuum the fins. Keep in mind that some HVAC systems make the cleaning process much simpler by allowing the coil to slide out of its housing.

What about the drain pan?

It's not just the evaporator coil that's in need of a good cleaning. The condensate pan and drain below it also need regular cleaning. Mold and mildew growth can easily block the drain from removing excess condensation from the pan, causing its contents to overflow and leak all over and around the HVAC unit.

Use the same shop vacuum, minus attachment, to empty the pan of any standing water. Once the water's dealt with, thoroughly clean the pan and drain of its mold and mildew growth. If the drain has a significant blockage, you can break it up using a small plumber's snake.

Once the clog is broken up and vacuumed out, you should pour a half-cup of bleach down the drain to prevent any future mold or mildew growth.

UV Lamps as a Preventative Measure

Once you're done cleaning your HVAC system's evaporator coil, it's time to look at ways you can prevent your hard work from being undone by future mold growth:

The best way of doing just that is by installing an ultraviolet (UV) lamp within the confines of the plenum. These lamps are designed to produce the UV-C waves commonly found in sunlight, making it the next best disinfectant. When these waves hit mold, they restructure the mold on a molecular model, preventing the mold from reproducing.

You may need two or more UV lamps to gain adequate coverage across the entire evaporator coil. The number of lamps you'll need will also determine the amount of energy you'll need to run your UV light setup. Go to this website for more information.