UV Lights in HVAC: Do They Actually Work?

UV lights in HVAC systems are marketed heavily. Here's what the science actually says.

Ultraviolet (UV) lights for HVAC systems have become popular. Understanding their actual capabilities helps you decide if they're worth the investment.

Types of HVAC UV Systems

Coil Sterilization Mounted to shine on the evaporator coil, running continuously.

**Purpose:** Prevent mold and biofilm growth on the coil

Air Sterilization Mounted in the return air duct, designed to treat air passing through.

**Purpose:** Kill airborne pathogens

What They Actually Do

Coil Sterilization (Effective) UV lights are effective at preventing biological growth on coils: - Keeps coil cleaner - Maintains efficiency - Reduces musty smells - Proven technology

Air Sterilization (Limited) Killing airborne pathogens is more challenging: - Air moves quickly through the system - Limited exposure time - May not achieve sufficient UV dose - Mixed research results

What They Don't Do

Replace Filtration UV lights don't capture particles—they potentially kill some organisms but particles remain airborne.

Eliminate All Germs Contact time and intensity matter. Fast-moving air may not get adequate exposure.

Clean Existing Contamination UV prevents growth but doesn't clean existing mold or dirt.

Realistic Expectations

Best Use Case Coil-mounted UV for preventing biological growth on evaporator coils. This works well and provides real benefits.

Questionable Use Case In-duct air sterilization with claims of eliminating airborne pathogens. Results are inconsistent.

Cost vs. Benefit

Initial Cost $300-800 installed for basic systems

Operating Cost Bulb replacement every 1-2 years: $50-100

Benefits - Cleaner coil (definite) - Better air (maybe) - Reduced odors (likely)

Our Recommendation

Consider UV For - Musty smell problems - Coil that gets dirty quickly - High humidity environments - Compromised immune systems (as part of larger strategy)

Skip UV If - Your primary concern is particles (get better filters) - You're expecting dramatic air quality improvement - Budget is tight (better filtration costs less)

UV lights are one tool among many. They work best for coil maintenance, less so for air sterilization.