Had HVAC biannual maintenance on Thursday. Technician pointed to stained looking rubber moulding inside blower cabinet. First he asked if I had any bleach to wipe it down. I said no. Then he said I needed to get an anti-microbial UV light system. I asked for and he provided an estimate, $475 plus bulb replacements every two years. It looked rather high until I looked online to see people quoted as much as 4 times more.
There are a large number of companies making lamps specifically for HVAC blower cabinets. There is research published by government authorities on the proven (though limited) efficacy of such systems. There is also word against the use of such systems by the likes of CARB (the California Air Resources Board) as they are said to be ozone generators (and, by a common description, that is how they work). Ozone generators are probably the last thing you want in your hvac system unless there are high levels of biological activity and no other way to stop them. Ozone is very toxic. The common way to stop such things is to reduce humidity, which is said to be high inside blower cabinets.
It turns out that the system I was apparently being quoted for, Fresh-Aire UV AHU, is not an ozone generator because it uses a 254nm light (unless you order the "odor control" option which includes additional 185nm bulb(s). A 254nm light looks like a good idea to me. If you look at the CARB list of suspect UV lamps, you will notice the Fresh-Aire UV model they have listed is different, not this one, and probably an older if not discontinued model. It is apparently possible for UV germicidal lamps not to be ozone generators. It's funny that Fresh-Aire's manufacturer does not tout the non-ozone-generating character of this system, though they decided do make non-ozone-generating aspect a major feature of their more expensive Purity system. Some manufacturers tout the ozone generation as a desirable feature.
Now in winter, an HVAC should not be a locus of high humidity. In fact the typical problem I'm facing is too low humidity, as dry cold winter air is heated inside making it even drier. So I add humidity with a room humidifier located right next to the main HVAC air intake. (Aha, ,this could be the thing causing rubber parts inside to stain.) I use this humidification only when the humidity gets very low, as I've dcciddd to minimize the use of supplemental humidification precisely because of the risk of mold, etc. But because I do sometimes add humidity, I should probably be adding the germicidal light inside.
In summer, it's different, the HVAC system is removing humidity, and when the blower is not running, indeed water evaporation from the coils can very well make the inside of the air handler high humidity.
There are a large number of companies making lamps specifically for HVAC blower cabinets. There is research published by government authorities on the proven (though limited) efficacy of such systems. There is also word against the use of such systems by the likes of CARB (the California Air Resources Board) as they are said to be ozone generators (and, by a common description, that is how they work). Ozone generators are probably the last thing you want in your hvac system unless there are high levels of biological activity and no other way to stop them. Ozone is very toxic. The common way to stop such things is to reduce humidity, which is said to be high inside blower cabinets.
It turns out that the system I was apparently being quoted for, Fresh-Aire UV AHU, is not an ozone generator because it uses a 254nm light (unless you order the "odor control" option which includes additional 185nm bulb(s). A 254nm light looks like a good idea to me. If you look at the CARB list of suspect UV lamps, you will notice the Fresh-Aire UV model they have listed is different, not this one, and probably an older if not discontinued model. It is apparently possible for UV germicidal lamps not to be ozone generators. It's funny that Fresh-Aire's manufacturer does not tout the non-ozone-generating character of this system, though they decided do make non-ozone-generating aspect a major feature of their more expensive Purity system. Some manufacturers tout the ozone generation as a desirable feature.
Now in winter, an HVAC should not be a locus of high humidity. In fact the typical problem I'm facing is too low humidity, as dry cold winter air is heated inside making it even drier. So I add humidity with a room humidifier located right next to the main HVAC air intake. (Aha, ,this could be the thing causing rubber parts inside to stain.) I use this humidification only when the humidity gets very low, as I've dcciddd to minimize the use of supplemental humidification precisely because of the risk of mold, etc. But because I do sometimes add humidity, I should probably be adding the germicidal light inside.
In summer, it's different, the HVAC system is removing humidity, and when the blower is not running, indeed water evaporation from the coils can very well make the inside of the air handler high humidity.
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