UV lights in HVAC systems

Sac Arrow

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This ties in to a couple threads I have going on, but the bottom line is I recently had a new HVAC install. Which, I am very happy with except for two things: One is the thermostat, but I think we are over that one plus I can put another one in if I really want. The second is this damned UV light.

No, I doubt Lennox sends condenser units with UV lights mounted in them. It was part of the contractor's "extra special" package. With regards to the equipment specs and their install reputation, and the cost (I picked a good time to do it) I was all about "dude let's do it!"

I didn't really feel like arguing about the UV light. And, by the way, I'm no stranger to UV disinfection systems. We use them in wastewater (and less frequently, in drinking water too.) They are effective, but those systems have to be carefully engineered so that the bulb spacing and the reaction tube or channel is correct so that a uniform UV dose gets delivered to all the water passing by. Otherwise, it is ineffective. Dangling a single UV bulb in a condenser plenum not designed for UV light distribution isn't going to do jack s**t for inactivating anything, at a useful level.

Well anyway I didn't yank the s**t out, I just wired in a switch to turn it off during the winter, when the AC isn't running, and I suspect I will not turn it on again even when I start the AC next spring. But you never know. It's there, and useful, if not used.

Oh, heh. A note on the inspections. S**t is weird on inspections lately. A month after the install, the state inspected the unit. Apparently they actually looked at things and someone was instructed personally on how to set up the thermostat. I was waiting for the county inspection to be over before I actually wired the switch in because I didn't want to f*** up the process. Well, a month later, the county came out. The whole inspection lasted three seconds. They didn't even notice (or care about) the dangling wire disconnected from the transformer feeding the UV light.

What are your thoughts on these UV systems?
 
I also think the uv is not there to provide perfectly clean air. It is probably better suited to keep things from growing inside the unit and cleaner air is good too.
 
I also think the uv is not there to provide perfectly clean air. It is probably better suited to keep things from growing inside the unit and cleaner air is good too.

Well, it might keep things from growing on surfaces directly exposed to a sufficient amount of UV light in order to kill stuff, but that doesn't constitute much of the total evaporator coil assembly.
 
Well, it might keep things from growing on surfaces directly exposed to a sufficient amount of UV light in order to kill stuff, but that doesn't constitute much of the total evaporator coil assembly.

You are probably right, but were it me, if I already paid for it, I'd run it.
 
Based on your knowledge of UV systems....mine probably isn't doing anything. o_O
 
You are probably right, but were it me, if I already paid for it, I'd run it.

It uses enough electricity, and the bulbs are expensive enough, that I really don't want to run it, more than it would be useful.
 
A quick Google gives one article by a competing technology, that says uv isn't safe and is ineffective. So maybe I would disconnect

Yeah I saw the article. I agree with ineffective, but I don't agree with unsafe. It's sealed up in a metal box.
 
They can produce ozone too.

I suppose, but actually the upgrade of the quoted HVAC system had an ozonation system incorporated in it. I suspect the ozone generated by UV would be dissipated pretty quickly before it became a hazard or corrosive to your home interior.
 
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