Central AC UV filter

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A customer of mine inquired about a UV filter to install in or on a central AC air handler to kill mold growing inside the cabinet and duct. Is anyone familiar with these, that can give me any detail on how and when they are used and work.
tia, Roy
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Customer? What kind of business are you in?
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I have had one for 4 years and it works. It is installed above the coil and it is on all the time. Steve

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What is it's intended function? Is it designed to kill mold, or is it an air purification system? Do you have the name and model of the unit?

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RBM wrote:

It kills stuff. It does not filter out any dust, pollen, dead bacteria carcasses, etc. so is usually used upstream of a filter.
nate
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OK, it kills stuff. In this case it's supposed to kill mold. My assumption is that this was recommended by the AC company to kill the mold in the blower system, and I don't understand how it would kill mold in the duct work that isn't near the UV light. Again, I'm assuming that if there is mold in the air handler cabinet, there would also be mold elsewhere in the duct
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RBM wrote:

Hmmm, Mold causing bacteria is air borne. Actually most germs are.
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Mold is not bacteria. But yes, I think it would be best to have the UV light before the filter, and possibly illuminating the filter to kill things before they go THROUGH the filter. Again, UV is very bad for your eyes. Make sure you have thick glass between your eyes and the light when it is on. Also, the bluish light you can see is not the UV.
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Best regards
Han
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Hmm. Seems to me I'd want it downstream of a filter, to protect the lamp. Dust on the lamp may limit the output and effectiveness. Unless you're going to clean it every month.
Remember, the filter in your system is not to protect YOU from dust, it's to protect your coil so they stay working longer.
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wrote:

    What exactly does it do?
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I think you may want to google for germicidal lamp. A fluorescent-like tube made of quartz glass, which lets UV light through. Handle with care, ie gloves or with clean paper, because fingerprints will damage the tube. Don't look into the light, and don't expose yourself (sunburn and worse). Used in biological safety cabinets (tissue culture hoods) to keep them sterile.
Glass absorbs UV.
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*Roy it sounds as though you want ultraviolet lights for inside the ductwork. I've seen these used in hospitals, but I don't have any details. I have also seen the ones used on water filtration units connected to wells. The idea is that the UV light kills bacteria. Try talking to an HVAC company.
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Thanks John, I don't know who initiated this, possibly the HVAC service company, and the homeowner is trying to get other opinions. From the homeowner description, it's just going to be some type of UV light installed in or on the air handlers. The claim is that there is mold growing inside, and the UV will kill it. I've worked with the ones on spas, and water systems, but I've never seen anything like this. It didn't sound like they were going to be installed throughout the duct, as you describe, which makes sense to me, just something in the blower. He didn't give me a number, but said it was wicked expensive. A Google search didn't turn up anything that was convincing to me. I suppose I should have him get more specifics from the contractor, so I have something more tangible to look into.
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RBM wrote:

I don't think they're *that* expensive... the industrial-sized ones I've seen (hotels etc.) are just fluorescent fixtures with UV tubes that are put into the ductwork just upstream of the filters. If someone wants one, I can't imagine it would cost more than a couple hundred bucks if one installed it oneself.
nate
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It sounds like YOU are the HVAC company, if he's coming to you with this question.
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I'm just involved with lots of trades, so my customers routinely ask me to check on things that don't seem quite right to them... and I did spend last night at a HIE

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*Roy I'm thinking if there is existing mold in the ducts that a remediation company should come in and clean first. The Ultraviolet lights are only placed near the air handler to my knowledge, not throughout the duct work so they would not do much for anything beyond. I would think that the source of the mold should also be addressed rather have something to keep the mold under control. Perhaps moisture is getting into the ducts and condensing or they are up against a moist surface such as a basement wall.
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OK, I get you. I'm not sure there is actually any mold inside the systems. It may be the HVAC company needs work. I think the homeowner is skeptical as well, at least regarding the remediation. This is your garden variety system, one handler in the attic for the second floor, and one in the basement for the first floor. The attic is hot and dry, and the basement is finished and above grade. Both units can't be more than 10 years old, and neither has the slightest bit of rust externally. I definitely need to dig deeper and get more info from the homeowner

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*I understand the position that you are in. My customers trust me so they ask what I think even though I have no knowledge or experience on the subject. What ever the issue is your customer should get several opinions before making any decisions. As you said the HVAC company could be looking for work or they are just incompetent. The only time I have seen an ultraviolet light unit installed on a residential system was on TV. It was an episode of Extreme Makeover Home Edition where one of the children had a condition and it was necessary to have a germ reduced environment.
Now I am going to reserve a room at a Holiday Inn Express :-)
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John Grabowski wrote:

The UV light around the evaporator coil kills the the micro-critters that can grow on the wet coil. That area of any HVAC system is where microbes can grow because that's where a lot of water and debris can collect. Some evaporator coils are coated at the factory with an antimicrobial compound that will help kill off the little beasties. Anything that can kill mold and mildew around the evaporator will also keep the odor level down. I've seen yeast grow in the darn things, some folks like to bake their own bread.
TDD
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