Controlling Mold: An HVAC Professional's Guide


How to Control Mold in HVAC Systems: An HVAC Professional's Guide

Important tools in industrial mold control. Mold in your HVAC system - it's a common enough problem, and it's enough to keep a facility manager awake at night.

Mold can grow just about anywhere. Give it a chance and it could contaminate your building, making occupants sick before you even see it. In fact, mold may be hidden, but its effects aren't. It can cause odors. It can aggravate asthma and cause headaches, skin irritation, and hay fever-type symptoms. Repeat exposure can increase sensitivity to allergens, or cause that sensitivity in the first place. It's not a matter of winning a battle against mold; it's more about waging an ongoing war.

Mold is always present in your building. There's more of it in warm, humid weather and less of it when it's cold and dry. But it's always there. Though you will never get rid of it completely, you can control it. Mold needs food and water to grow. Since, it can feed on just about anything - it can eat carpet and drywall, for cryin' out loud - you need to control it by reducing moisture and implementing an ongoing mold maintenance program.

One of the fastest ways to spread mold is through a forced-air HVAC system. But HVAC isn't always the bad guy. A well maintained system helps control humidity, which can slow the spread of mold. Remember, moisture is the culprit. Regularly inspect your system, not just for mold, but for moisture. Check drain lines and condensate pans. Are they draining properly? If not, the accumulated moisture can act as a mold factory.

What about coils? Are they clean and properly allowing air movement? Keep HVAC ducts, air handlers, blowers and plenums free of moisture.

Follow these basic steps when you have a mold or moisture problem:

  • Act quickly - mold can begin to grow in less than 48 hours. Turn off your HVAC system until the problem is located. Equip clean-up personnel with appropriate protective gear - an N-95 respirator at minimum.
  • Fix the leak, and take care of condensation or abnormally high humidity. Use wet vacuums to remove standing water.
  • Clean and dry non-porous surfaces to remove mold. Even dead mold spores can make people sick. For proper industrial mold control, use sound cleaning practices and isolate each area as you clean it so you don't spread spores to other parts of the building. Use a HEPA vacuum to keep spores where you want them.
  • Detergent and water effectively cleans mold on hard surfaces. For example, chlorine bleach kills mold, but if not properly used it can cause problems of its own. Also, specialized EPA registered coil cleaners can also help manage the spread of mold.
  • Replace or discard anything that can't be cleaned. Porous materials such as wallboard and carpet may have to go if they can't be properly dried out. Wet filters and insulation should be replaced.

Don't lose any more sleep over mold but do plan accordingly.  For a more thorough discussion visit