HVAC UV Lights for AC Systems–Do They Work?

In 1903, Niels Finsen won the Nobel Prize in Medicine for his use of ultraviolet light in the treatment of tuberculosis. Since then, ultraviolet lights have been widely adapted for all kinds of uses: sterilizing hospitals, sterilizing water, germicidal lamps in food establishments, and even curing nail polish faster. If UV light is so effective, how can it be applied to improving indoor air quality for residential HVAC systems? Will it kill mold and bacteria in HVAC systems? Yes, but you need to understand the priorities of indoor air quality and the types of UV lights available for residential HVAC systems.

Mold-Carrier-Air-Handler-800x531.jpg
Yuck! Mold and gunk build-up over 10 years in old air handler insulation and coil. The insulation was saturated with water. This can’t be healthy!

About 2 years ago, we installed a 19 SEER Lennox XC 21 air conditioner. During our most recent AC service, the technician also installed a TopTech HVAC UV light inside the air handler, which remains turned on 24/7. According to the technician from Engineered Air, HVAC UV lights are very effective at controlling mold inside the air handler. All mold in line-of-sight of the UV bulb will be killed, keeping the coil mold-free. He also mentioned that several clients with respiratory problems are even able to tell if the UV bulb has burned-out due to reduced air quality. I’ll let you know if I am able to tell.

HVAC-UV-Light-Installed-Lennox-800x600.jpg
TopTech UV light installed. Installation couldn’t be simpler. A strong magnet attaches the UV light mount to the inside of the air handler and the 24v ballast is wired directly into the air handler

Types of HVAC UV Lights

There are two types of UV lights for HAVC systems.

  • Coil Sterilization – A “stick type” light installed inside the return air duct near that sterilizes the air handler coil. A coil sterilization UV light runs 24/7 and is the most common type of HVAC UV light. It is also most reasonably priced. Amazon lists the TopTech 14″ UV light for $129.59
  • Air Sterilization – A complete UV light unit that sterilizes moving air. The UV light unit is installed in the return air duct and cycles on with the air handler blower. Sanuvox is a top-rated manufacturer of air sterilization systems.

Studies Prove Effectiveness

Two studies point to the effectiveness of UV light in killing mold and bacteria, one in hospitals and the other in a commercial HVAC system.

Maintenance

The TopTech UV stick light bulb is estimated to last 9000 hours, just over 1 year. Replacement bulbs cost about $70. Replace the bulb during each annual HVAC service and maintenance is nearly effortless.

Energy Cost

The TopTech UV light we installed is rated at 1.1 amps. To calculate annual energy costs, I used these handy calculators

For just under $100 per year ($24 electricity + $70 replacement bulb), my family has peace-of-mind knowing that we are breathing the highest-quality indoor air. It seems like a small price to pay. But it doesn’t make sense to install an HVAC UV light unless you’ve followed the indoor air quality priorities.

Indoor Air Quality Priorities

While HVAC UV lights are effective for killing mold, bacteria, germs and odors, make sure you have completed the indoor air quality basics:

  • Seal air ducts during renovation or construction
  • Install ducts in conditioned space
  • Ensure air-tight ducts, sealing all joints with mastic. See this Duct Sealing Guide from Building Science Corporation.
  • Install high-MERV filters, but be sure your HVAC system is designed for the higher static pressure of better filtration
  • Install UV light in HVAC system
  • Conduct regular maintenance, changing filters monthly and cleaning the coil annually

Benefits

HVAC UV lights:

  • Control mold and bacteria
  • Reduce colds and flus – germs are not re-circulated by HVAC system
  • Reduce smells / odors
  • Remove VOCs
  • Are more effective in humid climates than dry climates
  • Reduces clogging in condensate drain lines by preventing algae growth.
  • Maintain a cleaner coil, improving cooling efficiency and reducing electricity costs.

Disadvantages

HVAC UV Lights:

Manufacturers

Bottom Line

HVAC UV lights are an effective means for improving indoor air quality, but only after following the indoor air quality priorities. Install an HVAC UV light and experience healthier indoor air quality.

116 Responses to “HVAC UV Lights for AC Systems–Do They Work?”

  1. Garnet M Sleighter

    Where on the heat pump exchange is the best place to install the ultra light system, where it will be the most effective?
    Will it work if it is installed at the air intake?

    Reply
    • Brian Waterman

      I want information on getting a UV light system installed

      Reply
      • Bryon Thomas

        I suggest contacting a local HVAC contractor. If you need recommendations in your area, I suggest consulting Angie’s List (http://www.angieslist.com/) to find a top-rated contractor. Last I checked, it was $10 per month. Even if you subscribe only 1 month, it is well worth the cost to get a shortlist of contractors. Healthy breathing with your new HVAC UV light.

        Reply
        • Carl Hjort

          Do not use a AC contractor, the charge as much as $1500 for a top of the line system that only costs $400

          Reply
          • Brian Haanen

            We just had our uv light installed by an HVAC contrator for about $450

          • Leos Service Corp

            Not all HVAC companies rip you off We charge 150.00 for a uv light installed and we provide it free when we install a new unit

          • Mike

            Looking to put one in

          • Sarah Gilbert

            Morgan Air was going to charge me $1600 for a below system UV light where I would not have to replace the air filter, they said they would change it annually. I was charge $202 to replace the single bulb in the top of the handler.

          • Bryon Thomas

            Please share the HVAC UV light manufacturer and model number. How much is labor? The overall system cost strikes me as high, but you may have a complex install. Did the bulb replacement cost include parts and labor, including any trip charges?

        • Brad Phillips

          Byron- does the brand of UV light system make a difference- i.e.- is one any better than another as long as the UVC wavelength is in the 254 range?
          For SW Florida, does it make more sense to have a dual bulb system in the air handler (which is in the garage)- given that the return plenum leading to the unit is a fiber board that was kerf cut and adapted vs. an all metal?
          Thanks for any advice you can offer!

          Reply
          • Bryon Thomas

            I can’t really say if one brand is better than another without detailed testing. My HVAC UV light has worked well for my home: good bulb life (~24 months), low energy consumption, and easy to maintain. The Sanuvox UV lights do look interesting. Intuitively, I’m not sure “two bulbs are better than one.” This would be a good question for the manufacturer. As an additional note, the Indoor airPLUS standard from the US EPA prohibits installation of air handling equipment or ductwork in the garage (section 4.3). Here is their Indoor airPLUS Verification Checklist. The rationale is that the air handler will suck fumes from auto exhaust, paint, pesticides, etc. and distribute them throughout the house.

      • tom cribari

        does it matter if bulb is installed in the evaporator compartment the A=coil? I also had a gps installed is that a good thing?

        Reply
        • Bryon Thomas

          The UV light is usually installed on the supply side (where the air exits the blower). A second UV light can be installed between the “A coil” and “B coil.” See these Gemaire UV Light installation instructions for more detail.

          Reply
        • amy

          i believe the gps is a plasma unit. i’ve heard good things from pet owners about it reducing the pet smell.

          Reply
      • Carlos Alba

        I have a heatpump unit servicing approx 1620 Sq ft of living area.

        Reply
    • Dennis Roland

      Do the lights help with dust

      Reply
      • Bryon Thomas

        The HVAC UV lights do not help with dust. To reduce dust problems, I suggest air sealing ducts per this Duct Sealing Guide from Building Science Corp / Building America. You may also consider Aeroseal which seals the ducts from the inside, but that is not as optimal as properly installed ductwork. With properly sealed ducts and and HVAC UV Light, you will have a healthier indoor environment. Ideally, you would air seal the whole house, working with a RESNET or BPI professional.

        Reply
        • Ja morrell

          My ducts go up THRU the walls. No way to expose them. Can Aeroseal be sprayed in duct work? DUCTS been here since HOUSE was built in 1937. DUSTY NOW AND MUSKY. WANT TO INSTALL UV LIGHT TO HELP AS MUCH AS POSSIBLE. FROM READING, IT APPEARS I MIGHT NEED A LIGHT WITH DUAL ACTIONS. CAN YOU GUIDE ME? Sincerely, hipjaven@gmail.com

          Reply
          • Bryon Thomas

            Be sure to use an approved Aeroseal dealer who will measure the leakiness of your ducts before and after installation of Aeroseal. But first, conduct a visual inspection on as much of the duct work as is accessible to make sure there are no “duct disasters.” The AC coil also should be cleaned. After these things are done, you may consider installing a UV light. I installed a UV light on one side of the coil and have been happy with the performance for the past several years.

      • Kevin

        Dust no. DUST MITES YES!
        If you are allergic to dust Mites this will kill them. Although Dust mites are more likely on your pillow case , furniture , and Carpet. Not as likely in your air/airducts.

        Reply
        • Bryon Thomas

          Thanks for the clarification and good to know that HVAC UV Lights kill dust mites. Yes!

          Reply
    • Eric

      Best place to install a UV light on a Heat pump is upwind or before the Evaporator coil.

      Heat pumps don’t create enough heat to kill the mold and mildew on the evaporation coil when it goes into heat. The UV treatment on the Evaporator col will help eliminate these biohazards and keep your home clean.

      Reply
    • Bill

      I had a uv light installed by the same co that installed my hvac unit.it made the air on startup of my unit smell terrible for about 1/3 mins.

      Reply
      • Bryon Thomas

        The smell is likely due to the volume of stale air in the ducts being expelled. Mold, dirt, or dust inside the ductwork may cause the odor. Leaky ducts in the attic can also worsen odor since the leaks pull in attic air. After the ductwork air is cycled, the smell goes away.

        Reply
    • Patty Salmon

      I was quoted nearly $2000.00 for installation of a HVAC UV light. This seems quite high. Please advise.

      Reply
      • Bryon Thomas

        What was the brand and model of UV light? How many labor hours were quoted? Overall, the quote sounds high. Others have commented on costs approximately $500 to $1200 for installation. The Sanuvox UV lights do tend to run higher compared to the stick type UV lights like the TopTech. For a simple stick type UV light installation, I would expect 1-2 hours of labor.

        Reply
  2. Vernon Timm

    if the flex duct is not in direct exposure to the light, will deterioration still be a problem ?or should I just install the lamp in the return air intake where there would be no direct exposure to the lamp ?

    Reply
  3. Larry Schnitt

    I recently had a new 3 ton and a new 5 ton A/C units installed. The UV Bulbs were re-installed in the air handlers. The new Rheem units are working fine and cool our home quicker and more quietly than our old units. The problem that I noticed soon after the installation was a strong odor of Ozone in our bedroom. I did some research on the Internet regarding ozone, and found that the EPA as well as many other sourced are saying that ozone is dangerous to your health. That is can cause lung disease, heart problems and many other allergic problems. After reading your article above this comment form, I am very confused. If the UV Bulbs are very effective in removing mold and mold spores, they why do I have such a strong ozone smell in my bedroom? We had these UV Bulbs in our old units and never had this odor. Does this mean that the UV Bulbs were installed incorrectly, or can there be another problem with our new units? I am very concerned about this as we might be endangering our health. Can you please get back to me ASAP. Thank you.

    Reply
    • Mrs. Bac

      Larry, please let me know if you find out the answer to your ozone question. I am having a hard time getting ahold of anyone that will tell me the NM Wavelength of the bulb. It has to be a certain nm wavelength or it WILL produce ozone!

      Reply
    • Karen Marone

      It should not produce ANY ozone
      While ozone in some air purification applications is not always a bad thing, you do not want ozone-producing UV in your ducts because:

      Ozone from a UV light cannot be adjusted or turned on and off. Once the air pollution and odors are destroyed, you will smell ozone.

      Ozone in the presence of germicidal UV-C rays would corrode your air conditioner’s cooling system, and even separate the aluminum fins from the copper lines in the air conditioner cooling coil.

      Much of the ozone is destroyed by the UV-C rays anyway.

      Besides, you don’t need ozone to purify the air! The combination of UV-C, the purifying hydroxyls and negative ions can do the job.

      I did not write this article above, I got it from the website I added above.

      Reply
    • Bleau Gezter

      Not all UVs are the same, UV-C will not produce ozone.

      Reply
    • Billy bob

      It’s very common when the bulbs are brand new. Some of the uv systems do emit ozone, I make sure that I get bulbs that do not have ozone.

      Reply
    • whizatit

      The smell is probably more predominate due to the fact that you now have more airflow (no restrictions through the evaporator).

      Reply
    • Ray Odgers

      Ozone can be generated by UV lamps depending on the wavelength of the light generated. Ozone is produced at a wavelength of 185 nanometers. To avoid ozone production, use UVC lamps with a wavelength of 254 nanometers.

      Reply
    • John

      Ive just read that some bulbs used in aquariums to clean the water dont have a special coating that inhibits
      ozone production , hvac bulbs normally do have a coating , perhaps yours dont.

      Reply
      • Bryon Thomas

        The TopTech UV light in my system appears not to have a coating, but I can’t say for certain. A call to TopTech support would be required to verify 100%. Thanks for sharing!

        Reply
    • Carmen De Tommaso

      Please I have the same problem I also have problem with sinus and taste in my mouth

      Reply
    • Zenzo

      what could be smelling like ozone could be disintergration of the insulation inside your ac unit or electrical wire insulation in the coil section due to UV reaction. If your coil section has fibre glass insulation material , I suggest you get it ripped off ( fibre glass insulation absorbs moisture and provides great conditions for mold build up ) and install amarflex insulation and paint the new insulation and then use a spiral insulation which is uv resistant to protect the electrical cables insulation. I did this on a customer AC and the issue was resolved. I hope this helps.

      Reply
      • Bryon Thomas

        Great tip, Zenzo! Here’s a link to the Armacell insulation. Select “HVAC” in the left navigation. Looks like the AP Armaflex SA, AP Armaflex FS SA is the product to use (product link). It is self-adhering, so installation should be easy.

        Reply
  4. Zach mitchell

    On point!!

    Reply
  5. Is it Time to Upgrade to UV Lights During AC Repair La Plata

    […] in La Plata Maryland services will be more capable of handling UV-enhanced cooling systems. While UV lighting has been used for years, it wasn’t until recently when it was incorporated into a cooling system. […]

    Reply
  6. Ken

    Why are the questions posted here not answered by Housesogreen? They are questions all of us “not in the field” would like answers to.

    Reply
  7. Joe Random

    Larry, check to see what kind of UV bulbs were installed. Some UV lamps meant for pool use are specifically designed to release ozone, and yours should NOT be that type, but rather ones designed specifically to minimize ozone production. Of indoor-usage UVC lamps, Wikipedia says “Lamps designed to release UVC and higher frequencies are doped so that any UV light below 254nm wavelengths will not be released, to minimize ozone production. A full-spectrum lamp will release all UV wavelengths, and will produce ozone when UVC hits oxygen (O2) molecules.” You ought to be able to get ahold of a spec sheet like the following: http://www.ushio.com/products/uv/germicidal.php

    Reply
  8. Bonita

    Larry – read Ed McCabe’s Flood your body with oxygen – http://www.amazon.com/Flood-Your-Body-Oxygen-McCabe/dp/0962052728/ref=sr_1_2?ie=UTF8&qid=1442331558&sr=8-2&keywords=mccabe

    In spite of general tone sometimes reminiscent of “as seen on TV” ads, there is quite a bit of verifiable history and chemistry content. It explains the etiology of such physical responses and how to handle. VERY good. IMHO

    Reply
  9. Asbury Lemmon

    I had the Fresh Air model installed into our new home, i did the dual model one over the coil and one below. Had the type of system in our other home, I would will not have a home without UV light in the air handler. We can tell the air is cleaner and the dust bunnies disappear. New home should not have dust bunnies at all. highly recommend putting in UV.

    Reply
  10. John

    The TopTech unit you have is 24v AC. not DC. From the brochure:
    “Power:
    24V,
    50/60Hz.”
    50/60Hz is the frequency of the Alternating Current. 24v AC is the standard for HVAC control devices.

    Reply
    • Bryon Thomas

      Thanks for the correction! I updated the blog post to reflect “24v AC”.

      Reply
  11. Tina

    What would I need to install these as a business in the state of fl? I truly believe in these I have one and my husband is a hvacr tech so we know how to install them but need to know if we need to have a contractor license for.it

    Reply
    • Bryon Thomas

      A licensed HVAC technician in the state of Florida should be able to install HVAC UV lights. Check with the Florida Department of Business & Professional Regulation – http://www.myfloridalicense.com/dbpr/. HVAC manufacturers (e.g., Lennox, Carrier, Trane) may have additional training for the installation of their particular versions of HVAC UV lights. Good luck and healthy breathing!

      Reply
  12. mary harper

    I have a question? Hope you have an answer. I am having a problem with an oder in my home for a long time & have done everything to find where it is coming from. I have been reading about ozone from uv lights Do you think that could be the problem. i am actually getting sick from the smell & need some help going forward. Thanks for listening. Mary
    If you can’t help could you lead me to somewhere that I can get some relief

    Reply
    • Bryon Thomas

      Is the odor coming from your HVAC system? Or is it a musty odor from the house? Are you on a raised foundation (you have a crawlspace below)? The air could be infiltrating from cool dark places into your home. As a first order of attack, I recommend having a building performance contractor visit your home. This is not your typical general contractor! A building performance contractor has a deep understanding of how a house works as a system including air sealing, insulation, mechanical systems, comfort, and health. They will conduct a home audit (energy, comfort, health). They know how to make your home healthy. The two leading organizations in the US are Building Performance Institute and RESNET (Residential Energy Services Network). Search the the RESNET directory to find a professional in your area. This is a specialized field and these experts know how to diagnose and improve the comfort, health, and energy efficiency of your home. Only after you have done all of this would I consider adding an HVAC UV light to your air conditioning system. Good luck!

      Reply
  13. Mary Hegarty

    Hello, My concern is similar to the letter above from another customer named Mary, re: odor from the AC. We had a UV light installed a couple of years ago. The first one had an odor of bleach and we replaced it with one we were told would not give off that odor. The bleach odor was gone, but in its place was a different odor…difficult to describe…but apparent when the AC blower stops blowing. (The air then is cool and pleasant…no odor). The offensive odor is similar to the odor of plants and trees sometimes encountered in the spring here in FL. I thought it might be that coming through the air in AC. Now, we just had a new AC installed. The old one was 12 yrs old and horribly rusted, etc. We also had our ducts throughout the house completely cleaned. I thought that would end that peculiar odor, but it hasn’t. This odor was never present before that light was added. Can you help us resolve this? If it is the light, would it be difficult to remove from our unit? Thank you!

    Reply
    • Bryon Thomas

      It is difficult to diagnose your problem without an on-site inspection by a building science professional. Ironically, I don’t recommend an AC contractor. These building science professionals are highly trained in understanding your home as a system and can diagnose problems like this. Search for a contractor on Building Performance Institute or RESNET for a professional in your area. I also suggest reviewing the articles on the Energy Vanguard site such as How to Install Flex Duct Properly. Good luck!

      Reply
    • ADAM SPEARS

      Do a simple experiment. Cut power to just the UV light & continue to run the rest of your HVAC system, as you normally would for a month.

      Note any changes in air quality during that month.

      Then after a month without using the UV light, re-supply power to the UV light & run the HVAC system for a month, as you normally would.

      Note any changes to the air quality with the UV light on during this month.

      If your complaints diminish while the UV light was off; & re-surface while the UV light was on, the the source of your complaint stems from the UV light.

      If no, then the source from your complaints stem from something else in the environment of your home.

      Reply
  14. Walter

    Should the uv light be on 24 hours a day or only when the a/c unit is running

    Reply
    • Bryon Thomas

      Mold grows 24×7, especially in damp air that is not moving. This means mold will grow most quickly when the AC unit is not running. Therefore, the UV light should be on 24×7 for maximum benefit.

      Reply
  15. Walter

    The UV bulb my provider installed costs less than $18.00 on line. But they charged $175. Not acceptable.

    Reply
  16. Caryn

    We have a maintenance agreement with our hvoc company and we had one come yesterday and they said we need a Apco Fresh Air UV System with a quote of $1857! He said on our unit in the attic on the backside there is dirt and corrosion. Anyway, Is this something typical to do? Seems high and the last two maintenances this year have not mentioned. We have a very clean home and no odors. We have also had our air ducts cleaned in the last 18 mos. I just do let know if I am being taken advantage of and have never heard of anything like this. Please Help!

    Reply
    • Bryon Thomas

      Unfortunately, I have not personally used the Apco Fresh Air UV System. In a quick review of their web site, their systems provide “UV-C light and activated carbon”. How much is labor vs. parts in your quote? I suspect most is labor, if an HVAC technician bills out at around $70 per hour labor (Miami, FL market) + trip charge (~ $75). Installation should be a couple hours—if that. I did notice that the Fresh-Aire UV APCO-ER2 is $350-$500 on Amazon.com. Not sure if you are looking at that model.

      In general, I suggest getting a second quote.

      Remember, the coil may still get dirty even with a UV-C light if you do not have a good air filter and well sealed ducts. UV-C lights only kill mold and odors.

      Good luck.

      Reply
  17. Anne

    I am still unsure that I want this ozone emitting light on all the time. IT shines onto the carpet in the hallway connecting all our bedrooms….. and never goes out. Can I just unscrew it sometimes? We don’t seem to getting well from the flu and coughing, sinus infection, earache, etc. A long recovery, and we just do not know.

    Reply
    • Bryon Thomas

      With respect to the HVAC UV-C lights emitting ozone, the US EPA states this: “According to two studies, operating UV lamps installed in HVAC systems to irradiate the surfaces of air-handling units does not result in increased concentrations of ozone” (source). Remember, you should never touch or look directly at the UV light. If you see the light, I recommend installing it in a non-visible location: inside the air handler as that is where the greatest source of potential mold growth exists.

      Reply
  18. Bitsy

    Do UV lights for the AC system go up to 500 dollars to buy??

    Reply
    • Bryon Thomas

      Some AC UV lights can easily exceed $500 just for the parts. For example, I heard of a Sanuvox installation in San Antonio, Texas that cost $1500 for parts plus installation. The homeowner was very happy with air quality after installation.

      Reply
  19. FREDDIE ESCOBEDO

    I’VE HAD AC UV LIGHTS FOR A NUMBER OF YEARS. DO THEY NEED TO BE CHANGED PERIODICALLY, AND IF YES, HOW OFTEN?

    Reply
    • Bryon Thomas

      The short answer is yes. It depends on the life expectancy of each bulb by manufacturer. After 18 months, my UV bulb still worked, but I replaced it anyway. I estimate 18-24 months life expectancy out of an HVAC UV bulb. Contact your manufacturer for bulb life expectancies for your system.

      Reply
  20. Nathan

    As a student learning to be HVAC tech which one is the best so I can offer the best

    Reply
    • Bryon Thomas

      It’s hard to say which one is the best as they all have pros and cons. Why not take a look at Google Adwords Keyword Tool and determine which one has the most searches?

      Reply
      • Bob

        In Illinois, APCO Fresh Air UVC System – installed inside the main duct is around $1050-$1300 by most HVAC specialists. The bulb lasts 2-years but degrades into 3rd year… so replace every 2 years. Cost (2016) is around $90, and about $130 when HVAC technician it during an annual service. But remember, you get 2 years service life form bulb, and the TiO2 infused activated carbon matrix and electrical is lifetime warranty.

        Reply
  21. Anantha

    Do you know anything about Dirty sock syndrome? We installed a 3ton HVAC in 2010. A nasty smell started coming on when the A/C kicked in first time during summer months only not winter as the heater took over. Initial unit cost $5000.00, starting in 2011 this problem persisted and 4 different contractors did
    their own thing,replacing this and that so far amounting to over$4500.00. Now someone raises the above
    diagnosis and now recommending UV light! What can you tell me Bryon? Thanks for any advice.

    Reply
    • Bryon Thomas

      I recommend contracting a RESNET or BPI building specialist in your area to diagnose your problem. They are building science specialists, understand your “home as a system,” and have deep knowledge in diagnosing problems like indoor air quality. I know you have already spent a significant amount of money, but it is time to bring in the experts. I would expect an on-site diagnosis to cost a few hundred dollars, with additional repair costs, but you will most likely get to the bottom of your problem once and for all. Good luck!
      RESNET Contractors – http://www.resnet.us/directory/search
      BPI Contractors – http://www.bpihomeowner.org/find-a-contractor

      Reply
  22. Laurie Bonilla

    How much should I expect to pay to have a UV light installed bu my HVAC contractor? I was quoted $600! I thought this was quite high. Plus they didn’t mention the wear and tare on parts that may result from use.

    Reply
    • Bryon Thomas

      In your quote, what was the breakdown between parts and labor? The TopTech HVAC UV light goes for about $135 today on Amazon.com. The Sanuvox UV lights can easily cost $500-$1000 or more. The TopTech HVAC UV light is installed by placing the magnetic base inside the air handler and then connecting the 24v power wire inside the air handler. Labor for AC technicians varies by market. It’s about $75-$80 per hour in the Miami, FL market with a $75 trip charge. I would estimate 1-2 hours to install. Depending on the UV light specified, $600 may not be unreasonable.

      Reply
  23. Jim lumbard

    I wanted a 6 month pm on my ac units (3). After the tech looked at the first one he said I would need a uv bulb replacement. I told him I didn’t want it in the first place and did not want to replace it now. We have done pm with this company for 13 years. He refused to service the units unless I replaced the bulb. Is this a scam/good business?…

    Reply
    • Bryon Thomas

      I’m unclear what “pm” means but believe it may be related to a type of maintenance. Servicing your ac units contingent upon replacement of the UV lamps does not seem appropriate. Sure the UV lights will reduce mold and keep your AC system cleaner but millions of homes do not have AC UV lights and are regularly serviced. I suggest contacting a second HVAC company. Try Angie’s List for a reputable dealer/service company in your area.

      Reply
  24. Ron Saunders

    Love your Q&A. Lots of great stuff. Write anytime for technical information. I can provide an unbiased opinion and focus only on the technology.

    Reply
  25. Melissa Rivera

    We had to units installed about 8 yrs ago and upstairs unit runs out of freon every spring. We bought 10 year warranty by the way. Air conditioner co. Used a dye pack to find leakage. They put freon in about month ago and it totally leaked out again upstairs is hot. We called a new air conditioner co. With them we get free parts but we pay labor. They had a machine that picked up freon leak. Said it leaked in coils and one other place. Maybe this will finally end. Ok heres my problem. Upstairs has been hot and muggy and downstairs smells like mold and mildew when air is on. Smell blowing from vents. New company wants to put on uv lights on coils. Company cleaned both units but I still smell mold downstairs. Could it be mold in vents??? Air conditioner guys said no. This smell goes away in winter when heat is on. Moldy smell goes away. Please help??

    Reply
    • Bryon Thomas

      Since the AC service company cleaned the coils and you still smell dampness/mold, I’d almost be certain that installing UV lights on the coils will not help. The mold problem is almost certainly coming from the ducts. It could be leaks in the duct work, disconnected ducts, sagging ducts where water is collecting, or countless other possibilities. I recommend having a building performance contractor visit your home. This is not your typical general contractor or AC technician! A building performance contractor has a deep understanding of how a house works as a system including air sealing, insulation, mechanical systems, comfort, and health—and eliminate that moldy duct smell.. They will conduct a home audit (energy, comfort, health). They know how to make your home healthy. The two leading organizations in the US are Building Performance Institute and RESNET (Residential Energy Services Network). Search the the RESNET directory to find a professional in your area. This is a specialized field and these experts know how to diagnose and improve the comfort, health, and energy efficiency of your home. Only after you have done all of this would I consider adding an HVAC UV light to your air conditioning system. Good luck!

      Reply
  26. mike

    Have a house with a musty smell. I determined it was the flex tubes causing condensation. All the old insulation was removed and the flex duck are now properly strapped and replaced. But the musty smell still is in the house. I think it UV light would eliminate that musty mildewy smell in the house. The question is do I stick with coil UV light or a air purification UV light? Finally will there be damage to the flex or to the plastic drain pan using these UV lights? Is there anything I can do to minimize any damage or special installation instructions to eliminate any damage to begin with?

    Reply
    • Bryon Thomas

      Is the insulation inside the air handler dry? That could be a cause of the musty smell. I removed my old air handler and the foil-faced fiberglass insulation was soaked and smelled musty because it could never dry out. I cannot tell from your comment, but did you replace the flex duct as insulation is integrated into the flex duct? Did you clean the AC coil? New flex duct and dry insulation inside the air handler will help reduce the musty smell. If all of that is in working order, then you may consider installing an coil UV light. Only the parts directly exposed to the UV light have the potential for degradation. I have been running a UV light for the coil 24×7 inside my air handler for about 3 years with metal and plastic parts exposed. So far, so good, but your mileage may vary.

      Reply
  27. George

    Can you use the UV light with mini split AC units?

    Reply
    • Bryon Thomas

      Good question. Yes, they can be installed but they are a smaller version of the light shown in my article above. FreshAire UV and Ultravation are a couple vendors that sell UV lights for mini split ACs.

      Reply
  28. Sally law

    Have a UV for are pool and will consider it for air ??? What about water does it take floride out of city water????????

    Reply
    • Bryon Thomas

      I’m unfamiliar with the impact of UV light on water, but I have observed it as a common water purification technique, especially in commercial and hotel installations.

      Reply
  29. doug

    I had UV lights installed into two separate Mitsubishi Mini Split units.
    Both units — (with one in particular) are no longer blowing cold air compared to the level of air output and temperature output experienced prior to UV install. Past temperatures would follow in line with remote control temperature selected – ie. 65 degrees if wanted. Now after the install both units will not drop below 77 and don’t appear to be removing humidity or blowing as hard??
    Have you had experiences like this?

    Reply
    • Bryon Thomas

      Great question for the House So Green community. Anyone have a similar experience to Doug with mini splits and UV lights?

      Reply
  30. Camila

    Yup. Go look on amazon, there are so many energy efficient products on amazon.

    Reply
  31. Baja Pete

    The aforementioned UV lights appear to have 2 yr or less life span. Are there longer lasting LED UV lights for HVAC?

    Reply
    • Bryon Thomas

      Good question. I’ve not seen any HVAC LED UV lights. The expected life extension from an LED bulb would be convenient and energy-saving. Does anyone in the House So Green community know?

      Reply
  32. Tim Wallace

    We had these installed several years back after noticing mold on our bedroom ceiling vents. The UV lights were effective and air quality was improved. However, after the initial bulbs were replaced, we found at the next service that our filter (20x25x4) was destroyed – apparently by the UV light. Not sure if the new lights were stronger or the filter material changed. Our HVAC contractor thought we had a “rodent problem”, but a quick internet search pointed to the UV system. In our case, the filters are in line-of-sight, so I would recommend this be considered during installation. We have not found a good solution other than using our original 1-inch filters at the old return, or turning off the lights.

    Reply
    • Bryon Thomas

      Thanks for sharing your experience. UV light does deteriorate certain materials. With the increasing focus on “healthy homes” and HVAC UV lights being one part of a comprehensive strategy, it would be helpful for furnace filter manufacturers to indicate UV light compatibility.

      Reply
  33. Derrick

    Last week, AC contractor came to do 6 month service call, and said my Rheem AC UV Lights were not working and needed replacing. He scheduled another service visit for later to replace the bulbs. When the next repair person came to replace the bulbs, that repair person told me the ballast needed replacing, it was not working. The ballast had a lifetime guarantee and did not cost any to replace. However, I had already bought replacement UV bulbs at 380.00. My question, is this. If the first tech had done some more troubleshooting, and found the ballast not working, could the ballast being replaced solve the issue and I would not have had to replace bulbs (if they were still in good condition).

    Reply
    • Bryon Thomas

      It’s definitely possible that replacing the ballast during the first service call would have resolved your issue. It’s equally likely that the ballast went bad after the first service call. Do you still have the old bulbs? You may be able to get a bit more life out of them if the ballast was indeed bad during the first service call. I am surprised that the UV bulbs are so expensive at $380. Sure it’s aftermarket, but my TopTech UV bulb system (bulb + ballast + mount) cost about $135 and each bulb lasts 24 months plus.

      Reply
  34. Don

    Can you turn off the UV light in the summer when you don’t use the water and water filter to raise the humidity? If so this should extend the bulb life and cost less in energy. Thanks.

    Reply
    • Bryon Thomas

      You must live in a dry climate. Turning off the UV light is certainly a strategy for the reasons you mention. But I would be curious to know if you saw any mold growing once you turn on the light again.

      Reply
  35. Paul Roberts

    Interesting blog and thread. Spot on with the info you are giving out Bryon.

    Reply
  36. Kevin

    My Trane AC and Heat unit has a return air intake plenum near the floor. Can I place a uv unit within the plenum rather than within the air handler? Air handler directly abuts plenum. Same air runss through both. Would simplify installation greatly. 1250 sq ft condo. Longest duct run is 8 feet. Thank You.

    Reply
    • Bryon Thomas

      Installing the UV light near the coil is more effective. Most moisture is near the coil and therefore that is where the mold grows. You may receive nominal benefit by installing the light in the plenum, but the additional effort of installing the UV light near the coil will be more effective.

      Reply
  37. Steve

    Is there a danger of installing a UV light (Honeywell) in an insulated (or lined) metal duct? I have seen that it is not recommended, but there is no other option in my application, so I didn’t know if there was a danger or just less effective?

    Reply
    • Bryon Thomas

      The duct liner you have in the metal ducts likely has a foil face. Flex ducts typically have a plastic inner sleeve with an outer foil sleeve. The UV light deteriorates the inner plastic sleeve. Therefore, the insulated metal duct should be more resilient to deterioration. In the foil insulation inside my air handler exposed to UV light, I have not noticed any deterioration of the foil facing over the past 3.5 years. But your materials may vary. Be sure you are installing the light near the coil as that is where the mold grows.

      Reply
      • Steve

        Thank you! I believe the liner in my duct is fiberglass? It’s only a year old & has a fiber characteristic. The location is under the coils, due to the fact the the rest of the connected ducts are the plenum ducts which I don’t think will support the UV unit.

        Reply
  38. Nicole

    Hi, is there a way to install one of these lights without drilling a hole in to the duct work. We are in a rental and our neighbor is smoking like crazy. I noticed in one of your pictures it said that they used a strong magnet for one of the lights…

    Reply
    • Bryon Thomas

      For the light that I show, there is no need to drill a hole in the air handler. Simply open the air handler cover and affix the light’s magnetic base atop the insulation. Note, you will need to hardwire the light into the air handler, so this may require a service call from an HVAC contractor.

      Reply
  39. John

    We just installed UV lamps in our air handler units (2). One (downstairs unit) shines directly on the ceiling filter over where we sit watching TV and reading. I question whether direct exposure to the light can cause sunburn, or worse, skin cancer over time, like a tanning bed. The ceilings are eight foot and the UV ballast is maybe five above that. So maybe 10 – 12 feet away with filter in between. We take care to not look up into the duct, and turn the unit off when we replace the filter or have company. Thank you for your insight.

    Reply
    • Bryon Thomas

      Your precautions are smart. By example, it is common to see wall-mounted UV lights in restaurants or delis. Consider the deli at your local supermarket and you will likely see a wall mounted UV light glowing purple. Local building and health department laws have deemed them safe even though you can see the glowing light.

      Reply
  40. John

    So exposure over time is not an issue? Just don’t want to find out about the hazards ten, twenty years down the road…

    Reply
  41. Scott Wright

    Very informative. I could not have said it better myself. The only thing I may add or emphasize is that a maintenance agreement is critical to check and replace that bulb once a year. Unless the homeowner is capable and willing to do it themselves. I have heard from several homeowners with allergies and other respiratory problems that the UV lights improve the air quality and make the home more comfortable. The UV can make a considerable difference. Good article.

    Reply
  42. Ed Barr

    I have just installed a UV light in my ac intake duct. Due to the configuration the only place I could place the light was in the plenum chamber just above the ceiling intake vent. My concern is that now the intake is glowing blue-purple. There is a 3M Filtrete filter just inside the vent between the intake and the lamp. Is the filter enough to keep us from being harmed? The ceiling is 9 ft. and the vent is louvered. Thanks.

    Reply
    • Bryon Thomas

      It is not uncommon to see the purple glow of wall-mounted UV lights in food delis such as at your local supermarket. Employees are exposed to the UV light during their shifts (~ 8 hours) as well as shoppers. Ultimately, I recommend confirming safety with the manufacturer of your HVAC UV light.

      Reply
      • Troy

        In concerns to the uv light. If i,m reading this correctly, it sounds like your light is right above the filter but below the coil? Correct?? and your ceilings are 9’… regardless the location in this matter ” Do Not Ever Look at that Light”…. I will burn your eyes due to the UV-C. If you have to can out filters and the light is visible. Please wear polarized glass (Sun Glasses).

        Troy, Ret. Navy Seabee

        Reply
        • Ed Barr

          Yes. The light is above the filter and before the coil. I have a protected switch on the light to shut it off when I change the filter so no one ever sees the actual light. I am just wondering about seeing the blue glow through the vent/filter. Is that harmful?

          Reply
  43. Julia Hilliard

    Hi, would you recommend Stanley Steemer’s RejUVenate UV coil device? I am wanting to install one if this is a wise purchase for a household with a handful of cats and 3 dogs? The house is about 2000 sq feet, one large Carrier HVAC system about 8 years old.

    Reply
    • Bryon Thomas

      HVAC UV lights across brands are similar in technology. I don’t have personal experience with Stanley Steemer’s RejUVenate UV coil device. It looks to be a standard “stick type” UV light, likely a re-labeled product from another manufacturer. It should work well. With so many pets, you definitely want a good HVAC air filter to reduce pet dander. A good HVAC filter and UV light should improve your air quality, but there are still other unknown variables that could have an even greater impact such as leaky or poorly installed ductwork.

      Reply
  44. MaryAnn Clay

    Is there any way of determining whether our UV light is still effective. The purple glow seems to be the same intensity. or do we just go ahead & have it replaced after the estimated 2 year life span?

    Reply
    • Bryon Thomas

      To my knowledge, the intensity may decrease only slightly (perhaps less than 5-10%) with age and not enough to reduce effectiveness. I welcome any HVAC UV bulb manufacturers to comment with any testing that they have done. Personally, I replace the bulb once burned out.

      Reply

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