UV Light Recommendations

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  #1  
Old 10-02-08, 01:36 PM
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UV Light Recommendations

Howdy.

I have a Split A/C 5-Ton system and I started looking at the UV Lights available and there are so many to pick from that it makes my head spin.

What is the best one available in terms of bang for the buck? I am considering getting an air handler with a variable speed blower and running the blower 24/7 at slow speed, so the light will be on most/all the time.

Also, where is the best placement of the UV light(s) in your opinion?

Thanks in advance.
 
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Old 10-02-08, 03:00 PM
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More than one problem, more than one solution

First you need to identify what you are trying to accomplish.
Do you have family members who are sensitive to particulates (dust, pet dander) these require only better filtration and properly installed and sealed ductwork. If the problem is airborne pathogens then you would want to install irradiation but they are definitely not all the same and you need to be aware that if the application is not right you could end up creating more problems than you solve. Here is the link that Sharper Image does not want you to see http://www.consumerreports.org/cro/a...-sub/index.htm this will provide with enough unbiased information to keep you busy for awhile and good luck.
 
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Old 10-02-08, 05:11 PM
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I would not recommend a UV light. A service contract would be a better investment of your money. 1st the bulbs will have to be replaced every year or so $50 to over $100. 2nd If you have them shining on the coil you will need two one for each side to prevent mold. More cost in bulbs. You will still have to clean the coil which they will do on the service contract. 3rd If you are installing this in the duct to kill mold you will have been sold a bill of goods. The FPM feet per minute is to grate so there is not enough contact time to kill the mold as it passes by. Solution for this is to add more lights so mold is in the light longer. Most residential systems if the duct work is sized correctly will need 3 plus lights to get the contact time. I have dozens of photos from hospitals that have banks and banks of UV lights, guess what, they still have mold! Like I have stated above, a service contact will save you money and keep everything clean and if you do get a mold issue they will be looking in the unit twice a year and can bring this to your attention. Best thing for IAQ is filtration, 60 cfm of outside air when home is occupied and dehumidification. Oh by the way I am going to one of those hospitials on Friday to do air testing.
 
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Old 10-02-08, 06:55 PM
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Thank you both. This is a great subject and very healthy discussion

I have always used AprilAire filters on my system from new. Right under the furnace so that anything from the furnace up gets filtered.

I have the AprilAire 2400 and it is great! The times my A-coil has been opened for inspection, it has been super clean, except for the pan where the moister settles. I change my filter on a regular basis and overall, not much dust is in our duct system.

My wife is sensitive to molds and thus why I am looking at the UV lights.

One of the critical points of UV lights to kill bacteria, etc, is the time the organism is in direct contact with the light (as has been pointed out). Air moving at full speed gives the organism little to no time for good light absorption, thus poor performance. So here is what I found out so far and please let me know what you guys think.

With a variable speed motor, running it 24/7 at low speed will move the air much slower and thus exposing the organisms to longer UV light exposure. Second important thing is to place 2 UV lights about 18-20 inch apart along the lenght of the duct system so that the organism will have longer exposure to the light. The organisms go through the first UV light and then the 2nd UV light as they travel through the tunnel. Also important is to have a UV light that creates no ozone.

What say you?
 
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Old 10-03-08, 08:35 PM
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Joe that does not sound bad! But I still think a service contract will be money better spent! Id look at putting the home in a positive pressure to help keep everything outside than spend the money in UV lights.
 
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Old 10-06-08, 12:00 AM
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Originally Posted by airman.1994 View Post
Joe that does not sound bad! But I still think a service contract will be money better spent! Id look at putting the home in a positive pressure to help keep everything outside than spend the money in UV lights.
It almost sounds like you are saying that UV lights are of no value at all in an HVAC system?

Since I am redoing our duct work and installing a variable blower motor, I like to install UV lights unless of course they are of no use or of very minimal effect.

Anyone else has any first-hand experience if they felt or got any benefit from UV lights in their HVAC system?
 
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Old 10-06-08, 05:47 AM
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Yes!! The effects will be very minimal at killing air borne mold. Money better spent on a service contract. Id make sure you have a good media filter, dehumidification, and 40-60 cfm of outside air when home is occupied. This will be the best way to improve indoor air.
 
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Old 10-06-08, 09:40 AM
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Originally Posted by airman.1994 View Post
Yes!! The effects will be very minimal at killing air borne mold. Money better spent on a service contract. Id make sure you have a good media filter, dehumidification, and 40-60 cfm of outside air when home is occupied. This will be the best way to improve indoor air.
Absolutely - filtration is key. As I mentioned before, I have AprilAire 2400 and will be installing two of them in my new system. Every time the a-coil has been openned, it is amazinly clean and so is the duct work in general.

By the way, years ago I did a lot of reading about HVAC filtration. In a nut shell, electronic filters are not worth it because:

1) They are great at capturing tiny particles by static attraction but they are only effective for the first few days because once the surface area is all consumed, they cannot capture any more. You need to wash the plates every few days for true effiency and nobody cleans their filters that often.

2) Most electronic filters produce ozone which is not good.

Airman, going back to the UV lights, at what air volume movement and at what UV light intensity is needed to have UV lights be productive? Not looking for 100% effectivenes, just enough to be effective like say 50%?
 
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Old 10-06-08, 02:45 PM
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Slower air speed like you said with a VS blower will help. 50% still might be hard to get. You will need like eight feet of light at 300 FPM to get that. Id look at putting the house in a positive pressure to keep the mold out in the first place. Then there will be no need for the UV light.
 
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Old 10-23-08, 10:51 PM
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My research led me to believe that UV lights would not be that effective in my residential situation. This is my opinion based upon the posts and links I read during my search for improved air quality in my home. Isn't there an issue of Ozone creation with UV lights? or is that a different type of lighting technology?
 
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Old 10-24-08, 02:50 AM
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Originally Posted by dgbehrends View Post
My research led me to believe that UV lights would not be that effective in my residential situation. This is my opinion based upon the posts and links I read during my search for improved air quality in my home. Isn't there an issue of Ozone creation with UV lights? or is that a different type of lighting technology?
Most (if not all) of the electronic air cleaners do produce ozone.

As for UV lights, I think, I may be wrong, but I think some do and others do not. The ones that do produce very little however.

I am still not convienced that UV lights do not help. Imagine the stuff that must grow in the A-Coil under dark and moist setup. Even a regular light helps by not having a dark place where moisture exists. So a UV light would be that much more helpful - at a minimum, to keep the dark part out.
 
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Old 10-24-08, 05:39 AM
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All UV lights will produce ozone. Yes a UV light on both sides of the coil will help kill mold. A coil cleaning each year by your service tech will be able to clean the coil and kill any mold at the same time. UV lights can not clean the coil.
 
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Old 10-24-08, 01:39 PM
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Originally Posted by airman.1994 View Post
All UV lights will produce ozone. Yes a UV light on both sides of the coil will help kill mold. A coil cleaning each year by your service tech will be able to clean the coil and kill any mold at the same time. UV lights can not clean the coil.
All? So is this false advertising?

http://www.naturalsolutions1.com/ventductuv1a.htm
 
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Old 10-24-08, 02:02 PM
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Anything that uses electricity will produce ozone. The key is how much and is it an ozone generator.
 
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Old 10-24-08, 08:55 PM
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Originally Posted by airman.1994 View Post
Anything that uses electricity will produce ozone. The key is how much and is it an ozone generator.
Anything, like my electric tooth brush?

Look, most (all) electrical things may produce ozone, but coming down to Earth and being realistic, the question then becomes how much? Electronic air clearners produce Ozone in the ~.010ppm range which is not good for the health.

How much ozone do the UV lights produce that are labeled as non ozone producing?
 
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Old 10-24-08, 09:16 PM
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Every thing will be different! you can bet that they will fall some where between your electric tooth brush and a electronic filter. Let me clear something up. I am not against UV lights. I just fill that a service contract will have better results than UV. A service contract will save you money a UV light will not. UV lights have been poorly marketed over the years and there performance has been to say the least stretched. I have LOTS of pictures of AHU's with banks of UV lights and were the light does not shine there is mold growing. A service company could have seen this and cleaned this up before it spread and got worse.
 
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Old 06-12-09, 10:38 AM
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I know this thread is a little old, but I thought I'd add some more info in case anyone else reads it. My HVAC contractor is installing my ductwork tomorrow morning for a central AC system. I was going to have this installed, in fact he already had it mounted. But then we saw a note on the media air filter saying it should not be exposed to any UV light. The UV light manufacturer also recommended that the UV light not shine on any plastics, as it breaks them down over time. These two issues made for the likelihood of long terms issues. Coupling these new concerns with what I read about the debate around the effectiveness, made me decide to not have it installed. Not to mention the cost of the bulbs every year or two. I wanted good filtration for dust and allergens more than anything, this just seemed like a "nice to have."
 
 

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