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.
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
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.
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.
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
Glass absorbs UV.
*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
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.
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.
replace "roosters" with "cox" to reply.
*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.
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
*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 :-)
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.
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