UV lights are effective, but they work in a specific range. They’ll kill organic growths, such as mold or bacteria, but they have no effect on dust, pet dander or other allergens. In most residential cases, we will install the UV light near the coils to prevent mold or bacteria growth as air passes through. Since all of the air passes through the coils, this also kills growths in the air.
A UV light is just one element of an effective HVAC maintenance plan. You still need to use a high quality air filters, check it regularly and change filters as needed.
Ultraviolet lights require routine maintenance, including regular cleaning, and the bulbs generally should be replaced every year, at a cost of about $100. It’s very effective, but it’s not cheap.