>> In contrast, a plain old filter is likely to be extremely effective. A HEPA filter will catch almost all particles big enough to contain a virus, and a MERV 13+ or better filter is quite good. All you need is a filter with enough surface area that a good filter has low pressure drip.
The problem with installing a MERV 13 filter in a normal HVAC system is that the pressure (usually) isn't rated for it and can cause serious damage to the motor(s) as you noted, which is more common than people think (definitely the case in my home system).
UV-C installation is fairly simple; though I agree they are power hungry and you need to keep them on most of the time with maximum one power cycle per 24 hour period. They're cheap upfront and do work on normal coronaviruses, though.
Still the real problem is very little state-funded research on the topic, or development of some mitigation techniques for businesses that must run indoors. It's once again fairly useless bureaucracy.
Are they cheap upfront? I would imagine that just sticking a UV lamp in your furnace manifold by poking a hole in the side risks rapid UV damage to your furnace. And, if you’re going to slice up the manifold to make it appropriate for UV, you might as well put in a proper filter box instead. A decent MERV 13 or 15 filter from Aprilaire or another major vendor is not very expensive.
Yeah not too bad - a few hundred for reputable ones. Need to keep it far enough away from the filter, obviously, or risk damage over time (or just change out the filter more frequently).
I liken using UV-C (potentially) and a good filter as a defense-in-depth technique, just like masks, social distancing, sanitizer, temp checks (all which do very little on their own, but in the aggregate help).
UVC lamps are relatively inexpensive to install. Usually they're put before and/or after the cooling coil where, if you have a clean coil, the light will bounce through the fins and increase the path length of exposure. If it's not clean, the UVC helps to break down anything organic over time and cleans them up.
With a few exceptions of more complex units all of the recirculated air spends time passing through the coil.
UVC doesn't damage metal parts, but does effect some materials that would be common in residential installations
The problem with installing a MERV 13 filter in a normal HVAC system is that the pressure (usually) isn't rated for it and can cause serious damage to the motor(s) as you noted, which is more common than people think (definitely the case in my home system).
UV-C installation is fairly simple; though I agree they are power hungry and you need to keep them on most of the time with maximum one power cycle per 24 hour period. They're cheap upfront and do work on normal coronaviruses, though.
Still the real problem is very little state-funded research on the topic, or development of some mitigation techniques for businesses that must run indoors. It's once again fairly useless bureaucracy.
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