UV light install in Trane air handler

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Aug 18, 2020
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Here I go again on my own….

I’m going to install an Apco-x ultra dual (tuv-apcox-ud) into my Trane air handler given some mold I’m seeing (I’m in NC) due to high humidity. The air handler is a TAM series horizontally mounted. I trusted the company who installed the units and offer what they call “preventative maintenance” every 6 months recommended a UV light and $4k worth of coil cleaning. No thanks. I was less than impressed when I saw all the construction trash surrounding this unit that had to have its coil replaced two years ago. After cleaning the outside and inside of the air handler I am looking for best mounting options of the above UV light. Unfortunately I have duct board plenums both on return and supply side of the air handler and my concern is its long term condition in being exposed to the UVC light. I don’t want my family breathing the fiberglass dust if that stuff breaks down. Additionally, I’m considering where to put the lights so the wiring inside the air handler isn’t destroyed too. Should I just do the best I can with the included metal shielding on the bulbs? Would wrapping the exposed wiring with sacrificial electrical tape be of benefit knowing it’s got a defined lifespan? Is the duct board mounting a non issue? I’ve read to keep the lights above the coil if possible to minimize bulb exposure to water. My “A” coil is horizontal and looks like “<“ when the access door is opened. I will post pics later of the setup if it’s of benefit. Thanks in advance.
 
I agree that a great deal of HVAC companies have careless techs. My belief is that generates repeat business for future service calls…but that's another rant. There are however top shelf HVAC companies. They can be found by doing a lot of homework. Since I’m opinionated, typically Trane dealers-service centers are high quality. At any rate, a really good HVAC tech can install your kit and you will be set.
 
I agree that a great deal of HVAC companies have careless techs. My belief is that generates repeat business for future service calls…but that's another rant. There are however top shelf HVAC companies. They can be found by doing a lot of homework. Since I’m opinionated, typically Trane dealers-service centers are high quality. At any rate, a really good HVAC tech can install your kit and you will be set.
Thanks. I had done a ton of homework in selecting the same people who installed/serviced it and ultimately it depends on whatever tech comes out. I'm close to switching companies due to their current caliber of techs and the issues I mentioned above.

With that said, I am still looking to install this myself given I will know exactly what's been done and doing it the best way possible.
 
Mine was installed from the factory, or at least the installers that replaced my entire unit for me. It is installed right in the middle of the A coil, below the coils. (mine is vertical) This way it also shines down on the air filter, providing some virus/mold/bacteria killing effect to that.
When you open the door (flapper) to the air filter, you can check to see if the lamp is working. I generally replace mine every year with ones I get from Amazon. Much cheaper than calling the installers back out, which they'd love for you to do.
It definitely keeps the mold and stuff down, but not totally eliminated. It also does not harm any wiring in that location, and is easy to replace.
One thing that it WILL damage are 3M air filters! They will disintegrate when exposed to UV light. No other filter brand does this though, so just avoid 3M.
I called them for warranty on that and they told me tough luck dude.
If you'd like a picture, just reply to this post.
 
How does UV light reduce moisture??? Sounds like you need a dehumidifier.
it is meant to reduce mold in my use case. The moisture is going to be there in our current config regardless. Like you have rust cancer on your vehicle chassis, we have ridiculous humidity to contend with. Regional issues I guess.

Mine was installed from the factory, or at least the installers that replaced my entire unit for me. It is installed right in the middle of the A coil, below the coils. (mine is vertical) This way it also shines down on the air filter, providing some virus/mold/bacteria killing effect to that.
When you open the door (flapper) to the air filter, you can check to see if the lamp is working. I generally replace mine every year with ones I get from Amazon. Much cheaper than calling the installers back out, which they'd love for you to do.
It definitely keeps the mold and stuff down, but not totally eliminated. It also does not harm any wiring in that location, and is easy to replace.
One thing that it WILL damage are 3M air filters! They will disintegrate when exposed to UV light. No other filter brand does this though, so just avoid 3M.
I called them for warranty on that and they told me tough luck dude.
If you'd like a picture, just reply to this post.

Thanks for the heads up. I have a ton of 3M filters on scheduled changes. I am hopeful the UV light will be far enough back to not be affected, but I will keep an eye out. Always frustrating when they tell you to pound sand - makes you feel good having already spent the money with that company. I am considering how to punch through the cabinet on the one side to be in the middle of my "<" coil without drilling through some random 22 ga sender wire, etc. It'll be an adventure I guess. It sounds like your installation is the typical one I've seen a lot online, thanks for the offer of the pic but I think I got it.
 
Apco X had metal sheilds that will block UV rays from things they should not come in contact with.

I would focus your efforts on immediately removing the duct board, and get it converted over to real metal and insulate it properly so it does not sweat.

Duct board is not only dangerous, but it is a mold sponge.
 
Apco X had metal sheilds that will block UV rays from things they should not come in contact with.

I would focus your efforts on immediately removing the duct board, and get it converted over to real metal and insulate it properly so it does not sweat.

Duct board is not only dangerous, but it is a mold sponge.
Does the secondary bulb also come with the shield? That’d be great if so.

Good idea about removal/replacement. I’d rather spend the money here vs the “$4000 cleaning.” Any idea what’d this run on average?
 
RH above 50% will grow mold. Measure the temperature difference across the furnace/ air handler and evaperator coil 18" away from coil. 18° to 24° is design. 24° is max drop above coil could freeze up. 24° will pull out max RH. Use a probe style thermometer. RH is like heat flows high to low. Doors and or windows leak flows into the house from outside. Some electric companies offer a energy audit that includes a blower door test. That test tell how tight the house is.You tube has videos on it. Adding dehumidifier will do two things lower the RH and make the house more comfortable and might be able to raise the set point 1° to 3°.
 
Here is what the EPA has to say about home HVAC UV solutions. So while in a properly designed systems, UV can be very effective, that usually is not the case with home HVAC systems. If the HVAC "pros" can't design proper duct work, properly set up multi-speed air handlers, etc, I highly doubt any sort of UV solution will be effective. The exposure time is simply too short.

Screenshot 2026-02-23 134600.webp
 
Here is what the EPA has to say about home HVAC UV solutions. So while in a properly designed systems, UV can be very effective, that usually is not the case with home HVAC systems. If the HVAC "pros" can't design proper duct work, properly set up multi-speed air handlers, etc, I highly doubt any sort of UV solution will be effective. The exposure time is simply too short.

View attachment 325684
As you mentioned “May not be effective” isn’t necessarily the same as not effective, hence why I want to diy vs hire some guy who’s going to try and slap it together as quick as he can, leave a mess, and bill me an obscene amount. I bought high end equipment for sure so I’m trying to make my chance of success as optimal as possible.

To your point, iirc there’s studies out there indicating you don’t even need to run the system continuously to be of benefit for mold spore reduction, improved air quality, etc.

RH above 50% will grow mold. Measure the temperature difference across the furnace/ air handler and evaperator coil 18" away from coil. 18° to 24° is design. 24° is max drop above coil could freeze up. 24° will pull out max RH. Use a probe style thermometer. RH is like heat flows high to low. Doors and or windows leak flows into the house from outside. Some electric companies offer an energy audit that includes a blower door test. That test tell how tight the house is.You tube has videos on it. Adding dehumidifier will do two things lower the RH and make the house more comfortable and might be able to raise the set point 1° to 3°.
Thanks for this. I’m not planning on adding a dehumidifier for my unsealed crawlspace. Where would you recommend putting the lights?

Thanks for the tangential insight, gents but I’m really just seeking info on where to put the light.
 
As you mentioned “May not be effective” isn’t necessarily the same as not effective, hence why I want to diy vs hire some guy who’s going to try and slap it together as quick as he can, leave a mess, and bill me an obscene amount. I bought high end equipment for sure so I’m trying to make my chance of success as optimal as possible.

To your point, iirc there’s studies out there indicating you don’t even need to run the system continuously to be of benefit for mold spore reduction, improved air quality, etc.


Thanks for this. I’m not planning on adding a dehumidifier for my unsealed crawlspace. Where would you recommend putting the lights?

Thanks for the tangential insight, gents but I’m really just seeking info on where to put the light.
Some are made to fit above the drain pan under the evap coil. Others in the return air. Evaporator coils when the ac is running the condensate that the coilis pullout of the air is at 100% RH. As the air temp rises from 45° to room temp RH drops 35-40%.
 
I have read the UV lights they get installed in home HVAC do next to nothing. The HVAC companies seem to push air cleaners or UV lights.

I am told the only UV lights that do any good are expensive ones in hospital operating rooms.
 
I'm no HVAC pro but I did have my AC guy suggest a UV light install and a contract for return service, it was not $4k was total under $400 including the light but he ghosted me and never returned after I payed him and he installed the lamp.

I honestly have no idea but I think I would not mount UV that anything except the coils would get the light. If the box has mold but my thinking is the coils and pan is what stays wet? However all I know the UV could damage the metal coils? I have no idea?

I suggest call a few HVAC companies and pick them for info...
I would try and keep the light away from wiring or electronics. My guy wired my light to come on when the AC came on, that was my idea to make the lamp last longer as he wired it at first to stay on 24/7, I know the UV stops working after a time and requires replacement but who knows if it ever worked as I'm not going back under my house to look as its a mess!

UV lights must be BIG money makers as some of those Pyramid Network Marketing companies sold these UV lights you install yourself in the HVAC unit.

I live in Carolina too and have had lots of issues with mold. IF you could find a proper PRO Company that would always be around and can offer a proper designed UV light system ( not just a light screwed in the side ) with a service contract it may actually be a good investment as how can one put a price on moldy to then clean air?

Don't do what I did and use "JOE" The fly by night AC guy to install a light as he had no clue and was "poof" Gone!
 
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