By Anne Fonda
UV stands for ultraviolet light. UV lights have been used for years to kill bacteria, viruses, and fungi such as mold. UV lights in an HVAC system are an add-on feature to help improve indoor air quality (IAQ) and prevent mold growth on your air conditioner or heat pump system’s evaporator coil.
There are three types of ultraviolet light: UVA, UVB, and UVC. UVA and UVB are the UV rays that can cause skin cancer and sunburn. Short-wave UVC rays can kill microorganisms by penetrating their cellular walls and destroying both nucleic acid and DNA, which effectively deactivates bacteria, viruses, and mold.
UVC rays are also not safe for human exposure. Since HVAC UV lights are UVC lights, technicians must take special precautions to turn off the light before servicing the unit.
There are two main types of UV lights for an HVAC system – coil sanitizing lights and air sanitizing lights.
Your cooling system has an evaporator coil housed at the indoor air handler or furnace. The evaporator coil carries the refrigerant that cools your home. Because this area is cool and moist, it’s a breeding ground for mold and bacteria. Coil sanitizing lights target and kill these microorganisms.
Also known as UVC light for air conditioners, coil sanitizing lights look like long, thin fluorescent bulbs. Your HVAC technician places these ultraviolet lights for AC systems right above or next to the evaporator coil. The lights stay on 24/7. The bulbs will need to be replaced regularly.
Coil sanitizing lights can be especially beneficial if you live in a humid climate and run your AC a lot.
Air sanitizing lights are essentially an in-duct UV air purifier. Operating as a whole-house air purifier with UV light, the ultraviolet light targets and inactivates airborne mold spores, bacteria, and viruses that enter the air ducts through the return air vents.
They function as both a UV light for the furnace and a UV light for the air conditioner. They can be hard-wired so that they turn on and off based on your HVAC system’s operation.
This in-duct UV light air purifier system can help protect against the spread of viruses and bacteria.
HVAC UV lights work best when you have good humidity control. According to the Environmental Protection Agency (EPA), your home’s humidity level should stay between 30-50% for optimal comfort. Humidity levels above 60% provide an environment where mold and dust mites can thrive.
Proper ventilation and high-quality air filters or a whole-house air purification system can help improve your indoor air quality as well – filtering out allergens and contaminants such as pet dander and dust. The UV light in the ductwork can then target any airborne bacteria, viruses, or mold spores. The UV light next to the evaporator coil can prohibit mold growth and keep the coil cleaner longer.
HVAC UV lights are as well-known as an IAQ solution as HVAC air filters or whole-house air cleaners. So, you might have some questions. Here are the most commonly asked questions and the answers.
Yes. Studies have shown that UVGI effectively reduces fungi such as mold in air handling units. In addition, a Duke Medicine study found that UVC light can kill drug-resistant superbugs. The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) has done extensive research and testing as well to confirm the safety and usefulness of the technology.
The bulbs last 1-5 years, depending on the brand and light. Your HVAC professional can help you with a UV light maintenance schedule.
When installed properly by an HVAC professional wearing protective gear, these lights are completely safe for your family and pets. The UV lights target the enclosed evaporator coil and shine in the ductwork. At no time do these lights shine into a room.
HVAC UV lights use minimal additional energy. However, UV lights can increase your system’s efficiency by keeping the evaporator coil and ducts cleaner. A cleaner HVAC system operates more efficiently and can lower your energy bills.
Concerned about your indoor air quality? Trane sells sourced UVC light kits through our Supply business under a variety of brands. Each UVC air purifier, dehumidifier, and whole-house air purification system undergoes third-party testing to ensure the product is effective at improving your home’s indoor air quality and meets or exceeds ASHRAE standards.
Consult with a Trane Comfort Specialist near you for IAQ solutions tailored to your home and your needs.
Anne Fonda, Content Writer
A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.
She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism.
When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.
Expert review by Jennie Bergman, Senior Product Manager, Indoor Air Quality
Learn about indoor air quality – what it is and how to improve it for your family’s health and the health of your HVAC system.
The evaporator coil is the component of your heat pump or air conditioner that absorbs heat and moisture from the air inside your home. It then works with the condenser coil to produce cool air and complete the heat exchange cycle.
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