Replies

1. 
   TLRice | Jul 30, 2002 03:32pm | #1

   UVC's work best when installed such that they can keep the cooling coil clean. You didn't say what type of equipment the have or will have. In a residential style upflow furnace with an A-coil on top, the pair of UV lights would be installed on top of the coil to expose both sides. Upstream of the ccoling coil, if accessible, is prefered, but direct exposure is more important than which side. Upstream is frequently wholly or partially blocked by condensate pans. Check out the article on same in the current issue of Engineered Systems, at esmagazine.com . I don't have manufacturers of the product handy now, but can get back to you on this. Had a vendor of one product in my office a few months ago.

   Regular replacement of the elements is required, once a year, I beleive. Only pitfall I know of, other than cost. They are effective and will noticeably keep the coil and everything else in the system cleaner of mold and dust. Long term, no one knows yet. UV purification of water has been an effective treatment for several decades. I like it. When I upgrade my furnace this fall, I will install one in my house.

1. 
   rjw | Jul 30, 2002 10:56pm | #2

   Tim

   Interesting mag.  One article there said:

   "Though not presently sanctioned by health care construction and design guidelines, the "precursor" CDC infection control guidelines do recognize that "as a supplemental air-cleaning measure, UVGI is effective in reducing the transmission of airborne bacterial and viral infections in hospitals ... but it has only minimal inactivating effect on fungal spores"10 and bacterial spores16 . "

   That wa the article: The Answer is 3 When it comes to engineering solutions for IAQ in health care facilities, the combination of dedicated ventilation, microbial filtration, and ultraviolet germicidal irradiation ...."

   Was that thew one to which you refer?

   Is it true that the type of UV used for this application can be damaginbg to eyes?

1. 
   TLRice | Jul 31, 2002 03:53pm | #3

   Yes, that was the article. It is an interseting publication. I don't know if it is damaging to your eyes, though, I would not recommend looking at the elements for any extended period of time. I would bet that it is damaging. However, it works. I've seen tests in real-life, installed equipment. (The CDC is a semi-polital, governmental agency, that will eventually learn more about this, and most likely endorse UVGI)

   And, as the article pointed out, the answer is 3, of which this is only 1.

1. 
   rjw | Jul 31, 2002 04:56pm | #4

   Tim

   Thanks. 

   FYI, these things were recently discussed on the American Society of Home Inspectors members forum.  Avery knowledgable inspcetor named Jerry Peck posted the following:

   QUOTE

   UV lights are available in UVa, UVb and UVc. UVc is higher energy and is used to kill bacteria (and is considered harmful to people).They use UVc lights to help kill bacteria, mold, etc. in the return air stream and on the evaporator coil. I've been told they work well for those uses. You need to turn the lights off before looking or working in there.However (the big however), the UV destroys the insulation on the conductors (especially UVc), leaving bare wiring hanging anywhere the UVc reaches. The UVc also damages other things not UVc resistant (plastic condensate pans, pvc condensate piping, foam insulation on refrigerant piping, etc.).

   ENDQUOTE