Ultraviolet Air Treatment Systems: Do they work?

[stevealexander]

We live on the Gulf Coast and suffer tremendously from sinus problems. Recently I came upon an irradiation system system that is made by Honeywell. They report that it kills mold spores, bacteria, and viruses in the a/c system to reduce air pollution in the home. The unit goes on the air return side of the furnace and uses ultraviolet lights to clean the air before getting to the coil.

Has anyone had any experiences with these that they can share?

 

[EngineerBSME]

UV Ultraviolet light kills germs. Sunlight will do just as well. Sudden death occurs upon exposure so an extended time of exposure is not necessary. The most cost effective method of eliminating both good and bad bacteria in water and air is exposure to a UV light. UV light bulbs can be purchased at approx $10 each. The frequency of the light is important and must be in the UV range. If extended exposure to direct UV light is anticipated protect the eyes by wearing UV glasses.

There are two problems with UV systems. Make sure the system you select resolves these problems satisfactorily.
1. Bacteria and germs "Hide" behind solids. Solid particles of dust, flyash, airborne solids must be removed prior to the UV light. Since harmful germs are small the mechanical filter prior to the UV light should be at least one half micron with smaller being better. The collection efficiency of the mechanical fileter should be Beta Rated as verification that the filter removes a large percentage of the small solids. The Larger BETA RATING is better and should be like 99.9% Beta rated at 1/3 to 1/2 microns particle size.
2. The UV bulb can be unknowingly extinguished. The system must have a warning light, LED or whatever, to notify the user that the bulb is functional.