I'm currently in an HVAC course. We just completed a section on indoor air quality. We covered UV lights installed in the duct work. We were told that if a person installed a UV light with a pleated filter the air quality in the home would improve greatly. I guess my question is how good are these UV lights? Also, as far as installation, should they be installed in the supply side or the return? Thanks
UV will not work if installed in return or supply two much CFM! only good for direct contact! Best place for UV is at the coil! But to do the job correctly you will need one on both sides of the coil, and with some A coils you will need 3! I tell people to not waste their money! Better investment to buy a service contract!!
Drk are you telling me that there is less CFM at the A coil than the supply or return?? I don't know where you get your information but its completely backwards. Alot of bulbs won't even work properly in the A coils or supplies because the optimum temps for there maximium efficiencies are near 80 degrees. And the ones that will work in 55 degrees or less put off some small levels of ozone. A UVGI bulb isn't a cure all for any situation but its a good start.
UVGI is a proven disinfection technology, it can be used in HVAC air stream to help minimize the spread of infections due to air born pathogens. A UV system can reverse the HVACs system unintended roll as a distributor of pathogenic microorganisms if properly used.
The key to using any uv technology is the resonence time across the bulbs or PCO (Photo Catalytic Oxidation).
This might mean that just using bulbs it might take several in a series to meet the proper exposure times for the specific mold or pathogen. Penn State has a great web site on this subject and is the leading university on studies of UVGI usages.
We don't just use UVGI light on our systems because they don't remove VOCs. This requires an added technology known as photocatalysis.
There is no ultimate cure all for indoor air quality. But if you attack it in several processes your results will be much more to your liking.
1 Better filtration Merv rated filters say from merv 8 to merv 12 to get the particle count below 2.5 microns
2 UV light to render pathogens inactive.
3 PCO to break down the organic compounds in the air and remove them from the system.
Emmjam if you need some actual testing results from a system to help you render your own opinion e-mail me and let me know. Research this subject on the internet and you will come to a quick understanding of how effective UVGI lighting is.
HVAC contactors in general have a hard time understanding the benefits of indoor air quality. But everyone better get educated because the government will be shoving it down our throats before you know it with all the legislations that are currently being introduced.
Genesis Air Inc
Guess you did not read this line! Only good for direct contact! I have never seen a return (much) in 80's! So guess you are saying you will never have a bulb in the proper temp! IN THE RETURN, UNDER THE COIL ( UP FLOW ) SAME TEMP!!!!
Odd, you take a HVAC "course", and then get many opinions here that UV really doesn't do much. I think drk is on the right track, if you expose each surface of the coil to it, it should help a lot, the coil is where most of the crud grows.
I have a Carrier EZ-Flex 20x25 Merv-10 filter, which I am going to upgrade to the new Honeywell Merv-13 filter. I am going to install a Second Wind UV lamp (#2018) on one side of my flat coil, but I may buy one for each side. My AC is a 2 speed and runs in low 95% of the time at about 500 FPM, so the PD across the filter is very low.
Sometimes I wonder if it wouldn't be better installing a Merv-6 "pre-coil", and a Merv-10 or so "post-coil". I think most of the stuff you want to filter, starts at the coil. And where does all this dead stuff go that UV kills on the coil? If I install a UV lamp will my house get covered with twice as much dust?
You should try the April Aire EAC model 5000. Very little cleaning with kick ass results. All my hypochondriac customers love them. Media filter replacements required twice annually.
"Pigs get fat, Hogs get slaughtered"
I check this website every month or so during lunch and never take time to reply, but everytime there is a question regarding UV application drk immediately responds with an ill-informed answer.
genesis' reply is accurate with the exception of lamps able to operate properly at 55 degrees F. Philips has produced wind-chill corrected lamps for 5 years or more that are designed for operation at 55 degrees F. with air speed at 400fpm with no ozone production.
A properly applied UV system is capable of disinfecting viral and bacterial contaminate in as little as .25 seconds. Only 24" length required in direction of airflow at air speed of 500fpm.
Surface disinfection is readily accomplished with extremely low dose UV as a fixed surface allows 24-7 exposure. The technology is all about time and intensity, thus much time and low intensity accomplishes the goal of surface disinfection.
ASHRAE TG2.UVAS Ultraviolet Air and Surface Treatment
Chuck You are very wright UV can kill in the duct! But it has do be designed for each system, velocity and duct size! All of these off the shell UV lights are not going to do it unless you put three maybe four in line so you have the exposer time! This can be very cost prohibitive! The government has spend millions on UV for their post offices to kill anthrax which unlike most molds is very easy to kill with UV. They still don't have it down pat! The problem is the exposer time! When all is said and done the money it will cost to do it the wright way will be better spend on filtration and a service contract!
Things are changing and if you take a look around you will find you can offer your customers effective systems at affordable prices.
Buyer beware, certianly there are some making claims they can't substantiate.
Regarding Anthrax, Spores (including mold) are most resistant to UV and are large enough to be captured with filtration. UV can be applied to filters to disinfect Spores collected on a filter. The presently ultimate combination is Filtration/UV/PCO.
Hello chuck nice to get some help on this subject. I am aware of the phillips HOK series bulbs. But most of the supply houses exculding Carrier supply houses have equipment with the TUV364P bulbs. We installed a PCO system a couple of weeks ago that took 16 of the 5 foot HOK bulbs in a Homeland Security Training vacility for bio protection and odor control.And have some simular systems on Military Base's.
Drk I see your holding back I thought you were just being negative on UV systems. You have been doing some research. What I see in the field the supply houses are gung hoo about selling everyone UV lights but are not suppling the proper training on install practices and reccomended safety procedures with direct site of the bulbs or the pan damage that can occur.
PS Nice web site you have Chuck. I think I went by your booth at AHR in Orlando last year, wasn't at Chicago this year.
Genesis Air Inc
[Edited by genesis on 02-04-2006 at 01:20 AM]
another problem seldom mentioned with UV is that the killing is done right at the light, whether the fluid is air or water -- so the bacteria continues to grow downstream --
this was discussed in BuildingDesign & Construction Engineering relative to Legioneer's disease --
it also seems to me that the UV needs to be "tuned" for the particular bacteria present in a building -- maybe at CDC.gov --
harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!
Genesis Am I holding back MAYBE! I just don't like to see people getting ripped off! Their is not a lot of info out their for consumers and contractors and you know that their are a lot of company's that just go down to their supply house and pick one up install it, charge big money and the customer thinks they are fine! If the consumer can get more informed about them, I could push them! Until that time I guess You and Chuck will think I,m an #$@^ #@^! GOOD LUCK