How Effective Are UV Lights in HVAC Systems? UV (ultraviolet) lights are often added to HVAC systems to help improve indoor air quality. They don’t replace filters or clean all the air in your home, but they can be very helpful when used the right way. What Do UV Lights Do? HVAC UV lights use UV-C light , which can kill or deactivate mold, bacteria, and some viruses. They are usually installed inside the HVAC system, not in living spaces. Where UV Lights Work Best 1. On the Evaporator Coil (Most Effective) Prevents mold and bacteria from growing Reduces musty odors Keeps the system cleaner and more efficient This is where UV lights are most effective , often reducing microbial growth by up to 99% on surfaces. 2. Inside Ductwork Helps reduce germs in the air Air moves quickly, so exposure time is short Because of this, in-duct UV lights provide moderate air cleaning and work best when combined with good filters. What UV Lights Can and Can’t Do They CAN: Reduce mold and bacteria inside the HVAC system Improve system cleanliness Help with odors and allergy triggers They CANNOT: Remove dust or pet hair Replace air filters Completely disinfect all indoor air Maintenance & Safety UV lights must be installed safely inside the system Bulbs need replacement every 9–12 months Proper sizing and placement matter Bottom Line UV lights are most effective for preventing mold inside HVAC systems , especially on coils. They work best as part of a complete indoor air quality setup that includes good filters and regular maintenance. They’re a helpful upgrade—but not a cure-all.
