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Discussion Starter · #1 ·
HI,
I see a lot of UV offerings, many of which go under an A-Coil... or should I say nested between them.
Only a few seem to think it will destroy the plastic channels or pan for drainage.

Has anyone seen evidence in support or to the contrary?

Is it bad to put UV lights under an A coil in an upwind system?


The goal: to prevent mold from growing on the evaporator coils in the handler... and clean the air.
 

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I myself don't have a lot of experience with these lights. Here's a snippet from ACHR News that supports the possibility of damage.


"UV-C will Impact all Materials in an HVACR System Equally: Myth
There are many different materials found in HVACR systems, from metal to plastic to synthetic media, and all are impacted differently by UV-C. While metal is impervious to UV-C energy, plastic and synthetic media (filters) can be affected. Applying aluminum tape to plastic materials (electrical wires) will protect them from direct exposure. Likewise, UV-C lamps should not be installed in such a way as to expose synthetic filters typically found in residential and commercial HVACR systems to the UV-C energy".
 

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Mold requires an organic food source to grow. It won't naturally grow on a clean metal coil.

Use a good media filter (4"+ thick), merv 11+ at the air handler return - should mostly provent mold growth.
 

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HI,
I see a lot of UV offerings, many of which go under an A-Coil... or should I say nested between them.
Only a few seem to think it will destroy the plastic channels or pan for drainage.

Has anyone seen evidence in support or to the contrary?

Is it bad to put UV lights under an A coil in an upwind system?


The goal: to prevent mold from growing on the evaporator coils in the handler... and clean the air.
1: many drain pans are rated for UV exposure now.
2: UV doesn't "clean" anything. it can sometimes inactivate simple organisms.
3: many home grade UV systems are worthless. not enough power, bulbs lose UV output fast and are not replaced, bulbs burn out and are not replaced, etc.
4: even hospitals now don't do a lot of UV in the air system like they used to, they use multi-stage filtration. office areas will have two stage filtration (cheap merv 8ish before the fan, followed by merv11+ after), and the ICU areas will get additional HEPA filters after the heating/cooling equipment.

hospitals seem to focus more on using UV to blast rooms.
 

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soaker tub and backsplash, kitchen backsplash, Var fixes around the house.
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Discussion Starter · #5 ·
1: many drain pans are rated for UV exposure now.
2: UV doesn't "clean" anything. it can sometimes inactivate simple organisms.
3: many home grade UV systems are worthless. not enough power, bulbs lose UV output fast and are not replaced, bulbs burn out and are not replaced, etc.
4: even hospitals now don't do a lot of UV in the air system like they used to, they use multi-stage filtration. office areas will have two stage filtration (cheap merv 8ish before the fan, followed by merv11+ after), and the ICU areas will get additional HEPA filters after the heating/cooling equipment.

hospitals seem to focus more on using UV to blast rooms.
We had mold actually on our coils and on the blower fan blades and a little on the surface of the handler. We generally use merv11 or 13 filters, but 1" thick. The 4" filters cost 3 times what we pay for our 1" filters through discount places.

so far I have not been able to find one that will seat in a 14x25x1 return register.

I have friends and there whole families that were sick all the time with allergies, they put in a UV light and stopped going to the doctor. I have added an old pic of my coil... and one of my neighbors. they used a see through filter. Which does not contradict what you said.
I am OK with changing bulbs... I just want it as a line of defense and am hoping they will wire it to only come on when the system is running.

Do you know brands that dont lose effectiveness quickly?

Some put the UV in the supply, some under the coil. some in the return (not keen on the latter.)

From what I understand, UV-C band is the one to get.

I have heard that the plasma or ionics are good too. we are unsure about the ozone it may create and potential lung issues. My lungs are not great to begin with... but it is supposed to almost eliminate odors from cooking and such. I really want the air scrubbed as good as possible on a budget. At least until I can get a better job.
Oasis seems to have an interesting one that sticks to the blower fan.

My end goal is a system that pulls the humidity out of the air really well, and scrubs the air well, and eliminates potential spores or bio particles. The air here is not great. But hope to make it as good as possible in my condo.
 

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1" thick near-HEPA filters are a joke. I think your money would be better spent on having an HVAC tech re-do your return ductwork and make room for a 6" thick media filter.

your coil won't get moldy if it's clean.

FYI these are "equivalent" (they're not, but they're sold that way)
 

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I have no answers on this, only questions. I am 99.7 percent sure the blower wheels in my Daikins are porous and allow mold to grow. There is no other explanation as far as I am concerned.





I have a request in to Daikin to find out what type of plastic is used in the blowers so I can see if UV will affect it.



Most of what I read on the net about UV lights is unsubstantiated hype.
 

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Discussion Starter · #9 ·
I have no answers on this, only questions. I am 99.7 percent sure the blower wheels in my Daikins are porous and allow mold to grow. There is no other explanation as far as I am concerned.
This was my blower wheel at one point. Before I cleaned it. We have always used a high merv air filter.


I have a request in to Daikin to find out what type of plastic is used in the blowers so I can see if UV will affect it.
Would like to hear what they have to say.

Most of what I read on the net about UV lights is unsubstantiated hype.
What did you read? That it does not do much? That it will hurt the Handler? That it does wonders? I am not sure which hype you are talking about.

Included a pic of what my coil looked like before cleaned and when I inspected the return, the wall that the intake grate was on was not finished. I am not sure if that was mold or just dust, but I think it was mold.
 

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This was my blower wheel at one point. Before I cleaned it. We have always used a high merv air filter.




Would like to hear what they have to say.



What did you read? That it does not do much? That it will hurt the Handler? That it does wonders? I am not sure which hype you are talking about.

Included a pic of what my coil looked like before cleaned and when I inspected the return, the wall that the intake grate was on was not finished. I am not sure if that was mold or just dust, but I think it was mold.

Mostly advertisement type from comapanys with names like Bio Shield Teck. Then articles about UV lengths and what they kill, damages some plastic etc. Been trying to read up on LED UV. Now that you mention it have not seen much on AC damage. Destroy non-UV stabilized plastics in the air handler. Only items in the line of sight are affected such as drain pans. But no mention if it destroys all drain pans or only certain ones.


If someone wanted to the drain pan could be covered in aluminum foil or something similar or even possibly painted. In the mini everything in sight is plastic.



Living in Florida I see some plastic destroyed in short order, Like the cheap vent covers on my RV! Must assume it is UV doing it?
 

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soaker tub and backsplash, kitchen backsplash, Var fixes around the house.
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Discussion Starter · #12 ·
For a filter to be effective, there can't be leakage around it or downstream.

With merv 8 filter the blower wheel and coil should never need to be cleaned.
You have a point there I had not considered. If the resistance from the filter was high, it could have been somehow sucking air from the walls surrounding it. Maybe I should check them.
 

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Discussion Starter · #14 ·
where's your filter located? at the air handler inlet or return grill?

do you have a proper filter holder are a slot cut into the duct?
14x25x1 Inlet return grill.
 

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Probably have some return leakage then.

What size a/c? 14x25x1 pleated - better not be more than 2 tons.

You can likely have a media filter cabinet installed at the air handler inlet - that style filter only needs to be changed once a year and does a good job without restricting airflow.

You can put el-cheapo fiberglass in the return grill as a pre-filter.
 

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You have a point there I had not considered. If the resistance from the filter was high, it could have been somehow sucking air from the walls surrounding it. Maybe I should check them.
the more "effective" your grill filters are, the higher the leakage you'll have downstream from them, probably making the issue worse. I would suggest at a minimum making them merv 8.
 

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Discussion Starter · #17 ·
Probably have some return leakage then.

What size a/c? 14x25x1 pleated - better not be more than 2 tons.

You can put el-cheapo fiberglass in the return grill as a pre-filter.
1.5 ton condenser 2 ton handler.
 

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Discussion Starter · #19 ·

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