HVAC UV lights seem to be getting more popular. When inspecting an air handler they are often found especially in newer systems. But do these lights actually work as intended or are they just a waste of money? Lets find out.
What are the claimed benefits?
Manufacturers of hvac uv lights and installers claim that these keep the air handler clean & kill mold/bacteria in the air as it passes. Unfortunately all of these claims are not true. The lights are good at keeping surfaces of the air handler clean from microbial growth but they do not kill airborne mold/bacteria.
Why don’t they kill airborne mold?
Unfortunately the claim that they kill mold in the air isn’t true. An average size air handler (3 ton) will move around 1200 cubic feet of air per minute at a rate of around 10ft per second. At this rate there simply isn’t enough time the mold spores are exposed to the UV light to kill them.
How can HVAC UV Lights be beneficial?
These lights do have a useful application at keeping microbial growth from growing on surfaces but proper placement is key. The majority of dust buildup is going to be on the intake side of the evaporator coils. The second will be on the blower wheel. Unfortunately most installers will not place them in either location from my experience. Placing a light right in the middle of the A-coil is the best location as this is a great place for microbial growth to form since there’s a mix of dust and moisture. The picture below shows the ideal placement inside the cabinet.
Are all UV lights the same?
When choosing a light you will want to make sure that you get one that says “UV-C” as these have a shorter wavelength that kills mold. There are also more expensive systems that emit Ozone which you want to stay away from in a residential setting. High levels of Ozone can be harmful to people, pets & certain materials inside a house. Its best to just avoid this type of sanitization system completely.
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