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I recently visited a national trade show for HVACR folks and found this company: https://www.amazon.com/Blue-Tube-UV-Light/dp/B00D48XDO0/ https://www.amazon.co

I recently visited a national trade show for HVACR folks and found this company: https://www.amazon.com/Blue-Tube-UV-Light/dp/B00D48XDO0/ https://www.amazon.com/Blue-Tube-UV-Light/dp/B00D48XDO0/ Thought it might be applicable to computers, but realized that UV breaks-down PLASTICS as well, which is why you mostly find in ducting. Very cool stuff if you're into clean/sterile living. Note: Most of the dust in your home is comprised of human skin. Unless you've had an industrial vacuuming, other people's skin is moving around your house or gumming up the walls of your ducts. UV lights (and chemicals) are the only way to break that shit down.

wnevets 4y ago
Wouldn't UV-light in ducting generate ozone? Even relatively small amounts of ozone can be harmful. > When inhaled, ozone can damage the lungs. Relatively low amounts can cause chest pain, coughing, shortness of breath and throat irritation. [0] [0] https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-are-sold-air-cleaners#harmful-ozone https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-...
- RetpolineDrama 4y ago
  Carrier at least claims their UV upgrade does not produce ozone. Not sure how accurate that is though.
- Eisenstein 4y ago
  Ozone is produced at 185nm. Standard germicidal UV-C lights are ~250nm. The issue is that some germicidal bulbs do not filter out the lower wavelengths and thus produce ozone (sometimes on purpose since ozone is also germicidal). See [0]. [0] https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradiation#Lamps https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradia...
  - wnevets 4y ago
    >Ozone is produced at 185nm Where did you find that 185nm number? Everything I see on google says ~250nm, not to mention the original post is about 222nm UV.
    - lazide 4y ago
      ~ 250nm actually destroys ozone. Smaller than 240nm creates it, to various degrees, with the ideal frequency being 160nm. 185nm is 'produces a noticeable amount'. [https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391 https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391]
      - wnevets 4y ago
        So the 254nm referenced by the linked product could actually reduce the amount ozone in the air? Assuming of course it wasn't also emitting lower frequencies.
        lazide 4y ago
        Yes, but.... if you look at the paper, most of these lamps have some degree of lower wavelength light production. Some of them mitigate it through the glass they use, some of them make it worse. There is no good or easy way to tell. :(
        jefftk 4y ago
        The linked product peaks at 222nm and is filtered to exclude longer wavelengths. It's being compared to Mercury vapor lamps that peak at 254nm.
        wnevets 4y ago
        The blue tube product linked in the original comment I replied to says 254nm. https://www.amazon.com/Blue-Tube-UV-Light/dp/B00D48XDO0/ https://www.amazon.com/Blue-Tube-UV-Light/dp/B00D48XDO0/
        4y ago
  - jefftk 4y ago
    > Standard germicidal UV-C lights are ~250nm. The article is about KrCl 222-nm lights, which people want because they're safe [1] to shine on people, unlike Hg 254-nm lights. [1] Probably -- I'd like to seem some specific additional experiments before widespread deployment.
    - lazide 4y ago
      222nm is not safe to shine on anyone! It will definitely cause skin cancer. 254nm is also not safe. 254nm destroys ozone, interestingly. 240nm and smaller (160nm being the highest producing freq.) produce ozone. [https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391 https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391]
      - jefftk 4y ago
        I don't see anything in your link about 222nm causing skin cancer? It's short enough that it shouldn't be getting through the outermost layer of skin, which is dead.
        lazide 4y ago
        Welders have plenty of experience to contradict it. UV-C is usually blocked by the atmosphere, and most people don't get exposed to it directly - so it rarely comes up. But if you're sitting next to a UV-C generator, don't. It cleaves DNA the same as UV-B, and there is no reason to think it isn't cancer causing. There are a number of areas that can get exposed that have very thin epidermis, or none at all (eyes), though eyes would get retinal keratosis not cancer. That said, hopefully no one is spending enough time close to a high enough power UV-C source for this to REALLY be a problem. Welding Cite - [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5640727/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5640727/] Notably, while having a higher skin cancer risk despite being inside a lot (shop welders, not shipyard welders), the vast majority of welders in that sampled population will have been wearing heavy protective clothing continuously. There was a noticeable increase in risk of skin cancer on the neck, which is one of the few areas that is not always adequately covered. Anecdotally, I knew folks who didn't wear proper full coverage PPE when welding and welded a lot (auto body repair in one case, farm equipment repair in another), and both died in their early 40's from multiple malignant melanomas. One of them, it was 10+ all at once, and he died in less than a year. No one was surprised, unfortunately. They were ALWAYS sunburned from it, and they didn't spend a huge amount of time outside otherwise. That is a pretty broad spectrum source though. UV-C As Potentially Mutagenic/Causing Damage not caught by normal replication suppression mechanisms - [https://pubmed.ncbi.nlm.nih.gov/9951833/ https://pubmed.ncbi.nlm.nih.gov/9951833/] UV-C will also have no problem converting all sorts of organic chemicals into interesting, and often more toxic versions (albeit killing any organisms relying on their original structure in the process), same as UV-B or UV-A.
throw0101c 4y ago
> Very cool stuff if you're into clean/sterile living. One concern I've heard about UV (and ionization) stuff is that you're adding 'active chemistry' into your ventilation system, which could possibly cause strange reactions you may not want. Besides 'bugs' and dead skin, there are are VOCs and other chemicals that we use in our homes: how will those reaction? If these units are new and working properly, things may be fine, but how many homeowners will do (or have someone do) regular inspections/maintenance? Having this stuff in non-residential places may be fine because Facilities has a role in keeping HVAC working: regular people don't do that. Having good filters (MERV ≥13) will get rid of most of stuff you don't want in a simpler fashion.
- schiffern 4y ago
  HEPA gets all the hype, but if you can afford to recirculate the air for multiple passes (ie regular filtering, not a surgical theatre) then MERV-13 is the GOAT. It strikes a near perfect balance between particle interception efficiency and airflow volume. Paradoxically, a 'more efficient' filter will generally achieves lower real-world performance (CADR) because the airflow drops so much. The MERV rating are often hidden, instead you may need to look for numbers from a company-specific rating system like 3M's 'MPR 1900' or Home Depot's (yes, really) 'FPR 10.'[0] (I almost don't want to include this last paragraph of info, because by sounding like an ad it will automatically 'taint' everything else, but fuck it....) I find myself generally buying the 3M version (which is ~30% more expensive locally) which I observe has a much higher pleat count. That means more surface area (lifetime) and better pressure drop (airflow). By my math I come out ahead in cost per area of medium, which for me is a better metric than cost per filter. [0] https://airfiltersdelivered.com/blogs/helpful-tips/merv-mpr-fpr-ratings https://airfiltersdelivered.com/blogs/helpful-tips/merv-mpr-...
  - tempestn 4y ago
    Aprilaire 413 are our MERV 13 go-to. One other note not everyone may be aware of: if you have a central blower (aka furnace) that takes a standard 1" filter cartridge, it's usually not too expensive to add in a larger filter housing in the adjacent ducting. You just leave the default slot empty, or if you like, put a low-filtration backup filter in there. (Low filtration so as not to further restrict airflow.) So basically just because your existing unit only takes 1" filters doesn't mean you're stuck with that. Upgrade to 4" and you'll get better filtration and much longer filter lifespan.
thedougd 4y ago
I believe these are for keeping your evaporator coils clean and funk free rather than cleaning your air. The air movies past it much too quickly.
eutectic 4y ago
It's a myth that household dust is mostly skin cells. It only makes up a small percentage.
KennyBlanken 4y ago
You'll note the installation location - in the evaporator unit. It's to reduce mold growth in the evaporator unit, not sterilize air. UV units intended for installation in return or supply ducts are snake oil. A waste of electricity and money (the bulbs have a pretty finite lifespan.) The velocity of air in most ducts is such that anything flying by wouldn't be sterilized, and you can just install a large air filter (like the Aprilair 413 others have mentioned) and it'll bring a lot more benefits to the table, namely much better reduction of dust. The greatest problem with indoor air quality is offgassing of VOCs and other pollutants from construction materials, furniture, electronics, etc. If you want the best indoor air quality: install a large filter like the Aprilair or some equivalent, an air exchange device, and if you have a gas stove/oven, switch that to electric.
- lightedman 4y ago
  "UV units intended for installation in return or supply ducts are snake oil. A waste of electricity and money (the bulbs have a pretty finite lifespan.) The velocity of air in most ducts is such that anything flying by wouldn't be sterilized," If you just do the simple thing and point the lights in a self-facing ring in the duct, no, they will not work. The trick is to beam the light down the incoming pathway to drastically-increase the exposure time. Clean reflective surfaces in the ducting to even out the photon flux density will greatly help with this.

wnevets 4y ago

Wouldn't UV-light in ducting generate ozone? Even relatively small amounts of ozone can be harmful. > When inhaled, ozone can damage the lungs. Relatively low amounts can cause chest pain, coughing, shortness of breath and throat irritation. [0] [0] https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-are-sold-air-cleaners#harmful-ozone https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-...

RetpolineDrama 4y ago
Carrier at least claims their UV upgrade does not produce ozone. Not sure how accurate that is though.
Eisenstein 4y ago
Ozone is produced at 185nm. Standard germicidal UV-C lights are ~250nm. The issue is that some germicidal bulbs do not filter out the lower wavelengths and thus produce ozone (sometimes on purpose since ozone is also germicidal). See [0]. [0] https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradiation#Lamps https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradia...
- wnevets 4y ago
  >Ozone is produced at 185nm Where did you find that 185nm number? Everything I see on google says ~250nm, not to mention the original post is about 222nm UV.
  - lazide 4y ago
    ~ 250nm actually destroys ozone. Smaller than 240nm creates it, to various degrees, with the ideal frequency being 160nm. 185nm is 'produces a noticeable amount'. [https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391 https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391]
    - wnevets 4y ago
      So the 254nm referenced by the linked product could actually reduce the amount ozone in the air? Assuming of course it wasn't also emitting lower frequencies.
      - lazide 4y ago
        Yes, but.... if you look at the paper, most of these lamps have some degree of lower wavelength light production. Some of them mitigate it through the glass they use, some of them make it worse. There is no good or easy way to tell. :(
      - jefftk 4y ago
        The linked product peaks at 222nm and is filtered to exclude longer wavelengths. It's being compared to Mercury vapor lamps that peak at 254nm.
        wnevets 4y ago
        The blue tube product linked in the original comment I replied to says 254nm. https://www.amazon.com/Blue-Tube-UV-Light/dp/B00D48XDO0/ https://www.amazon.com/Blue-Tube-UV-Light/dp/B00D48XDO0/
        4y ago
- jefftk 4y ago
  > Standard germicidal UV-C lights are ~250nm. The article is about KrCl 222-nm lights, which people want because they're safe [1] to shine on people, unlike Hg 254-nm lights. [1] Probably -- I'd like to seem some specific additional experiments before widespread deployment.
  - lazide 4y ago
    222nm is not safe to shine on anyone! It will definitely cause skin cancer. 254nm is also not safe. 254nm destroys ozone, interestingly. 240nm and smaller (160nm being the highest producing freq.) produce ozone. [https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391 https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391]
    - jefftk 4y ago
      I don't see anything in your link about 222nm causing skin cancer? It's short enough that it shouldn't be getting through the outermost layer of skin, which is dead.
      - lazide 4y ago
        Welders have plenty of experience to contradict it. UV-C is usually blocked by the atmosphere, and most people don't get exposed to it directly - so it rarely comes up. But if you're sitting next to a UV-C generator, don't. It cleaves DNA the same as UV-B, and there is no reason to think it isn't cancer causing. There are a number of areas that can get exposed that have very thin epidermis, or none at all (eyes), though eyes would get retinal keratosis not cancer. That said, hopefully no one is spending enough time close to a high enough power UV-C source for this to REALLY be a problem. Welding Cite - [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5640727/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5640727/] Notably, while having a higher skin cancer risk despite being inside a lot (shop welders, not shipyard welders), the vast majority of welders in that sampled population will have been wearing heavy protective clothing continuously. There was a noticeable increase in risk of skin cancer on the neck, which is one of the few areas that is not always adequately covered. Anecdotally, I knew folks who didn't wear proper full coverage PPE when welding and welded a lot (auto body repair in one case, farm equipment repair in another), and both died in their early 40's from multiple malignant melanomas. One of them, it was 10+ all at once, and he died in less than a year. No one was surprised, unfortunately. They were ALWAYS sunburned from it, and they didn't spend a huge amount of time outside otherwise. That is a pretty broad spectrum source though. UV-C As Potentially Mutagenic/Causing Damage not caught by normal replication suppression mechanisms - [https://pubmed.ncbi.nlm.nih.gov/9951833/ https://pubmed.ncbi.nlm.nih.gov/9951833/] UV-C will also have no problem converting all sorts of organic chemicals into interesting, and often more toxic versions (albeit killing any organisms relying on their original structure in the process), same as UV-B or UV-A.

throw0101c 4y ago

> Very cool stuff if you're into clean/sterile living. One concern I've heard about UV (and ionization) stuff is that you're adding 'active chemistry' into your ventilation system, which could possibly cause strange reactions you may not want. Besides 'bugs' and dead skin, there are are VOCs and other chemicals that we use in our homes: how will those reaction? If these units are new and working properly, things may be fine, but how many homeowners will do (or have someone do) regular inspections/maintenance? Having this stuff in non-residential places may be fine because Facilities has a role in keeping HVAC working: regular people don't do that. Having good filters (MERV ≥13) will get rid of most of stuff you don't want in a simpler fashion.

schiffern 4y ago
HEPA gets all the hype, but if you can afford to recirculate the air for multiple passes (ie regular filtering, not a surgical theatre) then MERV-13 is the GOAT. It strikes a near perfect balance between particle interception efficiency and airflow volume. Paradoxically, a 'more efficient' filter will generally achieves lower real-world performance (CADR) because the airflow drops so much. The MERV rating are often hidden, instead you may need to look for numbers from a company-specific rating system like 3M's 'MPR 1900' or Home Depot's (yes, really) 'FPR 10.'[0] (I almost don't want to include this last paragraph of info, because by sounding like an ad it will automatically 'taint' everything else, but fuck it....) I find myself generally buying the 3M version (which is ~30% more expensive locally) which I observe has a much higher pleat count. That means more surface area (lifetime) and better pressure drop (airflow). By my math I come out ahead in cost per area of medium, which for me is a better metric than cost per filter. [0] https://airfiltersdelivered.com/blogs/helpful-tips/merv-mpr-fpr-ratings https://airfiltersdelivered.com/blogs/helpful-tips/merv-mpr-...
- tempestn 4y ago
  Aprilaire 413 are our MERV 13 go-to. One other note not everyone may be aware of: if you have a central blower (aka furnace) that takes a standard 1" filter cartridge, it's usually not too expensive to add in a larger filter housing in the adjacent ducting. You just leave the default slot empty, or if you like, put a low-filtration backup filter in there. (Low filtration so as not to further restrict airflow.) So basically just because your existing unit only takes 1" filters doesn't mean you're stuck with that. Upgrade to 4" and you'll get better filtration and much longer filter lifespan.

thedougd 4y ago

I believe these are for keeping your evaporator coils clean and funk free rather than cleaning your air. The air movies past it much too quickly.

eutectic 4y ago

It's a myth that household dust is mostly skin cells. It only makes up a small percentage.

KennyBlanken 4y ago

You'll note the installation location - in the evaporator unit. It's to reduce mold growth in the evaporator unit, not sterilize air. UV units intended for installation in return or supply ducts are snake oil. A waste of electricity and money (the bulbs have a pretty finite lifespan.) The velocity of air in most ducts is such that anything flying by wouldn't be sterilized, and you can just install a large air filter (like the Aprilair 413 others have mentioned) and it'll bring a lot more benefits to the table, namely much better reduction of dust. The greatest problem with indoor air quality is offgassing of VOCs and other pollutants from construction materials, furniture, electronics, etc. If you want the best indoor air quality: install a large filter like the Aprilair or some equivalent, an air exchange device, and if you have a gas stove/oven, switch that to electric.

lightedman 4y ago
"UV units intended for installation in return or supply ducts are snake oil. A waste of electricity and money (the bulbs have a pretty finite lifespan.) The velocity of air in most ducts is such that anything flying by wouldn't be sterilized," If you just do the simple thing and point the lights in a self-facing ring in the duct, no, they will not work. The trick is to beam the light down the incoming pathway to drastically-increase the exposure time. Clean reflective surfaces in the ducting to even out the photon flux density will greatly help with this.