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I looked into implementing this once. Some surprising things I learned: 1. You need UV-C (typically 222 nm), not just any old UV bulb off Alibaba/Wish/Amazon.
by schiffern 2y ago
I looked into implementing this once. Some surprising things I learned:
1. You need UV-C (typically 222 nm), not just any old UV bulb off Alibaba/Wish/Amazon.
2. You need an extremely high UV light intensity to kill viruses if the air is just flowing past the bulb (vs shining UV on a coil to prevent bacterial/fungal growth, which is the typical usage), and you need more intensity the faster the air is flowing. Usually this requires multiple bulbs.
3. You need to replace your UV-C bulbs every 1,000 hours or so, because they rapidly lose intensity with operating time.
Just putting a "black light poster" bulb in your ducts won't accomplish anything, other than perhaps giving you a false sense of security.
- bri3d 2y ago> You need to replace your UV-C bulbs every 1,000 hours or so I don't think this should need to be the case. Low pressure mercury arc lamps (253.7nm) last 10,000 hours in water treatment applications - a much more palatable replacement timeline (1 year) vs every few weeks! The short-lifetime bulbs are usually 222nm Far-UVC bulbs, which are safe for human exposure. These shouldn't be necessary to treat air as part of an enclosed HVAC system. I feel that the hype around 222nm / "safe" UVC has done a disservice to just using "dirty" 253nm UVC, which kills everything just as well as long as you keep people from being able to look at it.
- schiffern 2y agoThanks for the correction. It's been a while since I looked into it! Even replacing bulbs every 1 year seems like a lot more than people are bargaining for. Most people seem to expect UV will be a "Set It And Forget It" solution (hence why they prefer it over filters), so they risk neglecting the necessary replacement interval.
- dzhiurgis 2y agoSounds like it needs software subscription added /s IMO people wouldn't mind replacing it if it was easy to access.
- mandmandam 2y ago> You need an extremely high UV light intensity to kill viruses if the air is just flowing past the bulb Could you put a long tube-shaped 222-UV bulb inside a larger tube with a UV-reflective coating inside to enhance the efficiency? ... And, can UV bulbs be mirrored, so they reflect as well?
- mab122 2y agoThis sounds exacly as UV water treatment lamps
- mandmandam 2y agoI don't know if this is a silly question but, if it works for water then why not air? Is it an overheating issue?