dusty evaporator coil

4 Places Mold Is Most Likely to Grow in Your HVAC System

When most people think of mold growth, they tend to associate it with a home’s damp, humid locations, like the bathroom, kitchen, and crawl space. But did you know that under the right conditions, mold can also grow in your heating, cooling, and ventilation (HVAC) system?

Below, we’ll explain more about what mold needs to grow and where mold growth typically occurs in HVAC systems.

What Allows Mold to Grow?

Mold needs four things to grow on a surface: moisture, a food source, oxygen, and a suitable temperature range.

  • Moisture. Molds grow fastest in wet conditions or in a place with muggy air. This is one of the reasons why mold growth is such a concern in homes with excess humidity or water damage.
  • Food source. Mold can digest just about any type of organic matter (matter that contains carbon atoms). Mold can feed on such things as soap residue, the organic matter in dust, or even the oil your skin leaves on a metallic surface.
  • Oxygen. Molds are a type of organism that requires oxygen to survive. That being said, mold growth can occur even when oxygen levels are low.
  • Temperature. Not all types of mold have the same temperature preferences, but most can grow in an environment between 60°F and 90°F.

Mold growth typically occurs inside air conditioners during stretches of warm weather when the AC is not in use. Water droplets collect inside the system, and the surrounding warmth and dust on the HVAC components create an environment where mold can get a foothold.

Where Does Mold Grow in HVAC Systems?

If you smell a musty, dirty sock odor coming from your air ducts, your HVAC system may have mold in one of these components:

  • The drain pan. Air conditioners and high-efficiency furnaces draw moisture from your indoor air. That moisture becomes condensation the collects in a drain pan. A dirty, neglected drain pan combined with all that water can foster mold growth.
  • The condensate drain line. This is a pipe that allows water to exit the drain pan and empty outdoors. If you don’t get your drain line flushed at least once annually, sludge can build up inside of it and contribute to mold growth.
  • The evaporator coil. This part of your indoor air conditioning unit draws out heat and moisture from your indoor air. Without routine maintenance, the coil can become coated in dust. That dust, combined with the condensation the coil collects, can provide mold with the food and moisture it needs to thrive.
  • The air ducts. If your air ducts are old, or if they’ve never been sealed, there’s a good chance that moisture is getting in through gaps. If your air ducts are dirty and contain dormant mold spores, that added humidity inside your ductwork can create a suitable environment for mold to grow.

There are multiple ways to prevent mold growth in your HVAC system. First, use an air filter with a MERV rating of 13 to keep out mold spores. For even more advanced filtration, consider installing an air scrubber that will not only capture contaminants like mold spores but also destroy their DNA and render them unable to spread. Equally important, remember to get your air conditioner maintained once a year so that the indoor and outdoor AC units can be cleaned and the drain line can be flushed.

For top-quality HVAC services and indoor air quality solutions, trust the experts at Monarch Home Services. Contact us online or give us a call at (661) 271-6099 today!

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