The Dual Roles of In-Duct UV Lamps
Ultraviolet germicidal irradiation (UV-C) at 254 nanometers disrupts microbial DNA, preventing bacteria and mold from reproducing. However, marketing claims promising that a single UV bulb in your ductwork will 'sterilize all incoming airborne viruses' defy basic radiation physics.
The Residence Time Problem
To kill airborne pathogens traveling through an HVAC duct at 400 to 500 feet per minute, an organism passes the UV bulb in less than 0.2 seconds. Achieving lethal germicidal dosage in a fraction of a second requires massive commercial UV arrays, not a 15-watt residential lamp.
Where UV-C Truly Excels: Surface Coil Decontamination
While fly-by airborne disinfection is modest, UV-C lamps installed directly over the wet air conditioning evaporator coil and drain pan are extraordinarily effective. Because the coil surface remains stationary under continuous UV illumination 24 hours a day, the light completely eradicates mold, fungal colonies, and bio-slime from aluminum fins, preserving heat transfer efficiency and eliminating 'dirty sock syndrome' odors.