HVAC UV Filter system: Fact or Crap?

[Psychstache]

anyone have any insight into whether or not a UV filtration system added to an HVAC actually works as advertised? Will this help improve air quality, or is it flashly marketing crap?

I have tried to google machine and most articles I find seemed to be from biased sources (HVAC companies).

[lthenderson]

I guess it depends on what you mean by "improve air quality".

If you are looking to install one in an environment where there are lots of virus or other pathogenic organisms floating in the air, then I suppose it would be worth it. But in most houses, this is not the case or a big concern anyway and it does nothing to remove anything from the airflow which is what triggers asthma and breathing issues. All it does is render anything living, to dead status and then that dead organism will flow into your house and be breathed into your lungs as normal. In order to remove those, you need to concentrate on a filter.

[Sibley]

Are you a hospital or lab working with pathogens? If so, probably a good idea to have in conjunction with more traditional filters.

If more typical residential or commercial space, good filters changed at appropriate intervals, combined with regular cleaning of the space will be better.

[NaN]

Based off your title, UV "Filter" is a crappy name. It is really UV Sterilization. The UV lights won't filter anything out of the air - they just might kill a little bit that passes by.

UV disinfecting of air is big now because of COVID. There is some positive science behind it because, well, that big bright thing we see in the sky emits a lot of it and does kill stuff that is out in it too long.

But how much will the HVAC UV light kill? I don't know. How would one measure that scientifically for an HVAC system? Short answer, it probably has never been evaluated. So really, it is all a sales pitch to convince it will work. :)

Consider this article from a biotechnologies lab company.  It says:

For sterilizing surgical instruments in a medium UV box, it might take 5-10 min. For sterilizing an 8-foot biosafety cabinet in a lab, a common recommendation is 30 min.

And this is all for stationary equipment while the UV light is hitting surfaces for a long duration. The air in the HVAC is probably near the UV light just for a few seconds each time it passes by. A home might change over its air once every 3 hours, at best. So I doubt the few passes any mold, viruses, and bacteria have in the UV light in the HVAC system are really impacted much at all. I bet the inside walls of the HVAC near the UV light will be very sterile, though, lol. And back to the first point - it doesn't filter anything.

My verdict says its crap!

[BudgetSlasher]

UV is definitely not a filter, it does not remove anything. UV damages DNA (thus killing) things like fungus (mold), virus, and bacteria that are in the air.

If your house is a place with a lot of people coming and going or an immunocompromised person lives there they might be worthwhile. If you are looking to reduce dust, pollen, or other allergens they do nothing.

[BicycleB]

Also, I've heard rumors that they ionize the air, causing faster decay of the seals in the HVAC system. Fwiw.

[GilesMM]

Do you have reason to believe there are microorganisms in your air?  How does your evaporator coil look?

[Daley]

I think it may also be worth categorizing types of UV treatment, too. Everything discussed up to this point has been UVC air treatment for pathogens. UVC is the end of the ultraviolet light spectrum that blinds you, gives you a sunburn, and can kill microbes. Does it help? Yes, kinda. Can it cause accelerated damage to the HVAC system damaging plastic and rubber parts faster if not properly placed? Absolutely. If you're wanting UVC treatment to try and kill off airborne pathogens, you're better off with room-level blowers with a UVC bulb in it.

However, there's another UV light treatment that hasn't been mentioned yet. UVA light (you know, the black lights people used to use in college with neon posters when they got high) coupled with a titanium dioxide nanoparticle covered lattice is used to produce short lived hydroxide ions through photocatalytic oxidation. The devices are better known as hydroxyl generators. This is an air purification scrubber that was researched and pioneered by the University of Wisconsin-Madison and NASA back in the 90's and found to be effective against COVID as well. The UV light doesn't damage components, nor do the hydroxyls damage equipment, apparently, and the resulting short lived hydroxyls will basically work as both a deodorizer and pathogen killer. They're really popular in remediation businesses as stand-alone devices, but HVAC integrated equipment is harder to find.

I've used hydroxyl generators myself under circumstances where an ozone generator was impractical or hazardous to use with remediation. They work, they work well in fact. Kinda makes a room or house smell like the air over a meadow field covered with dew in the morning sunlight. I honestly like them so much I wanted to integrate one into our replaced HVAC system a couple years ago just to have for additional air purification and odor neutralization, but couldn't find any, and didn't feel like trying to build one myself.