Design Build Doug

UVC for HVAC-Case Study in Local Hospital

Posted on May 7, 2010     Leave a Comment

The pictures above clearly show the effectiveness of using UVC lights to remove bio-organisms from the evaporator coils (..effectively cleaning the coils) of an HVAC system. All of that crud shown in the bottom of the two photos came from the coils, after less than two months of the UVC light install. The crud seems to be dead now, but was previously alive (I presume) and was present and most likely reproducing within the air handler of this HVAC system.

The use of UV lights in water filtration systems is fairly common. The use of these lights in HVAC equipment is not. Why?..I asked myself over a year ago. The answer is: no one wants to get caught with snake oil…and, there are associated filter and non-metal component degradation issues (due to the UV exposure over time)when used in most residential setups. Overall, UV lighting industry lacks government regulation so there have been and currently still are many products on the market that are simply ineffective. Ineffective at what you ask?

These lights (when applied properly) are supposed to kill 99.9% of the bio-organisms (i.e. mold, mildew, viruses, etc.) that grow inside the evaporator coils of your HVAC system. The evaporator coils are part of your “air handler.” Meaning, unless you’ve been using a top of the line filter with rubber gaskets, the likely-hood is good that a good percentage of the conditioned air inside your home or business is passing over these bio-organisms…after getting filtered. This occurs because any particulate that bypasses the filter and sticks to the evaporator coils, though, you can always get your coils completely disconnected, cleaned, and reinstalled.

Why do the bio-organisms form on evaporator coils (probably more than anywhere else in your home or business)? Because there is a food source..particulate(i.e. dust..SOME of which will pass through even the best filter money can buy) , and water (which is created when the semi-warm air from your HVAC return passes over the cool coils..creating condensation).. That said, a superb media filter like the AprilAire that has gaskets will cut down on this occurrence tremendously, and is all I currently depend on in my own home.

So, don’t freak out, these bio-organisms (most of which are naturally occurring outdoors) probably won’t kill you..they haven’t yet right? But, they could be the cause of some discomfort (i.e. allergies).

How do you greatly reduce or eliminate this discomfort? Well, in a commercial setting like this hospital that uses large metal chilling units in which the lights are not in close contact with disposable filters, I say install UVC lighting in your HVAC system, in conjunction with a premium filtration system. But, in a residential situation, where there is one or two smaller units for each house, I’d stay away from the UVC lighting for now. The reason why, is because the UVC lights can eat up your air filter over time and even some components of the air handler.

Let me clarify. In regards to indoor air quality and your HVAC, I feel a good filter is priority number one, and in some larger scale settings that UVC lighting (among other things like duct/attic sealing) is secondary. So if I owned a hospital or stadium..I would definitely spring for both. With an ROI of one year or less on the lights (in a commercial application), which is what these distributors claim..seems like an obvious choice to me, for commercial chiller application.. In smaller more traditional application, the issues relating to filter and component degradation must be addressed prior to install, because filtration is most important! With a revamped system that addresses these issues(like use of metal to protect the filter from the light..), I feel these lights have a good chance of becoming common place in homes.

To summarize, the lights kill harmful bacteria while making Large Commercial Chilling Systems run more efficiently, ultimately saving places like stadiums and hospitals lots of money and providing their attendees health benefits. Retro fitting this system in your home would cost you less than $1000, and the yearly bulb change out, done by a professional, would cost you less than $250, but again..I would hold off on putting it in your house until they get filter degradation worked out.

Do your homework regarding air purification (beware of any purifier that produces OZONE, this particular product does not). Not all UVC lights are equal in performance, a study done by the EPA (of participating UVC light manufacturers) seems to support claims that this light is the strongest and most effective of its kind. Ultimately, the light itself seems to work great, but you’d better make sure its not going to eat your filter..

Check out this cool video to see more. -DC