UV lights for HVAC systems are designed to use a particular wavelength of light — 254 nanometers — that is absorbed by the DNA of microorganisms. After exposure to the UV light, the organisms are unable to produce the proteins they need to survive. Although the UV light does not kill the germs immediately, it nullifies their ability to cause harm and shortens their life span considerably.

The volume of air inside your home is immense. Treating it effectively as a whole is nearly impossible because UV lights can also be harmful to humans. Inside your air handler, however, is a different story. Your HVAC system draws the air into its evaporator unit and forces it out through air registers — the vents — placed around your home. Installing the UV light inside your evaporator unit makes perfect sense, as the air must pass over the UV light as it is circulated.

UV lights for your HVAC will not alleviate your symptoms caused by allergens, since dust, as well as dead fungi, will still be present. Also, if your HVAC system has damaged or leaky ducts, the vacuum created in the ducts could draw in new contaminates from attics and crawl spaces, limiting the UV light effectiveness. UV light is only effective when microorganisms contact its light spectrum. Any of the aforementioned contaminates shielded from its light spectrum will survive.

UV lights are installed right above the coil, so UV lights shine on it continuously to prevent the growth of mold. Ductwork UV Lights or Air Germicidal HVAC lights are meant to kill airborne allergens and pollutants making their way through your return vents.