UV-C (ultraviolet C-band, 254 nanometer wavelength) is a germicidal radiation that damages the DNA of bacteria, mold spores, and viruses, preventing them from reproducing. UV-C lamps installed near the evaporator coil sterilize the coil surface and drain pan, where biological growth tends to form in humid HVAC systems.
UV-C lamps in HVAC are not air purifiers in the traditional sense — they don't filter particles. They prevent biological growth on wet metal surfaces. Charleston's humidity makes this particularly relevant: every cooling coil in our climate is wet for 7+ months a year.
Two installation types: coil sterilization lamps point directly at the evaporator coil; in-duct air sterilization lamps shine into the airflow itself. Coil sterilization is the more common and more effective use.
UV-C bulbs lose effectiveness as they age and should be replaced per manufacturer schedule, typically annually.
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