ATLANTA — Mold growth in HVAC systems can distribute spores throughout an entire building via the air distribution system, making HVAC mold one of the most serious and costly forms of indoor mold contamination — and one that requires specialized expertise to address properly.
HVAC systems are vulnerable to mold growth when moisture accumulates in the air handler, ductwork, or drain pans. Common causes include oversized cooling systems that cool the air too quickly without adequately dehumidifying it, clogged condensate drain lines, and duct leaks that allow humid air to enter the system.
Detection of HVAC mold typically involves visual inspection of accessible components, air sampling from supply registers to detect elevated spore counts in the distributed air, and swab sampling of suspected mold growth on HVAC surfaces. Borescope cameras are used to inspect ductwork that is not visually accessible.
Remediation of HVAC mold requires cleaning or replacing contaminated components, addressing the underlying moisture source, and verifying that the remediation has been effective through post-remediation testing. The National Air Duct Cleaners Association (NADCA) has developed standards for HVAC system cleaning that complement the IICRC S520 mold remediation standard.
Prevention of HVAC mold involves regular maintenance including filter replacement, condensate drain line cleaning, and periodic inspection of the air handler and accessible ductwork. Building owners should also ensure that their HVAC system is properly sized for the space it serves — an oversized system is more likely to create moisture problems than a properly sized one.
