The thought of mold and bacteria multiplying in the HVAC system and being circulated through ductwork is troubling to anyone who wants a sanitary home. It can be a serious threat to those with breathing issues such as asthma and C.O.P.D.
You’ve heard that ultraviolet lights effectively sanitize air and equipment. Is this true? How much do they cost? Are they worth it?
These are the questions answered in this guide to UV light cost and effectiveness.
Do UV Lights Kill Mold, Bacteria and Viruses?
Ultraviolet lights were shown to kill mold, viruses and bacteria more than 100 years ago. In fact, in 1903, Niels Finsen was given the Noble Prize in Medicine for using UV to effectively treat patients with skin infections.
Today, UV lights are used for germicidal use in hospitals, restaurants and grocery stores. And they have been shown effective in killing sterilizing an HVAC system. Here are two examples:
1). In 2012, a study at Duke University Medical Center showed that UV lights killed 97% of bacteria that were resistant to antibiotics, the so-called superbug bacteria that are the toughest to kill.
2). The Journal of Applied and Environmental Biology reported in 2001 that germicidal UV radiation significantly reduces airborne fungi in air handling units.
This is a question we’re hearing often, and there might be good new! UV germicidal lights are known to kill viruses of many kinds.
Can UV Light Kill COVID-19?
UV light might kill coronavirus! According to the US Centers for Disease Control and Prevention, “Vaporous hydrogen peroxide, ultraviolet germicidal irradiation, and moist heat are the most promising decontamination methods” for COVID-19 commonly called coronavirus.
More on UV Light from the CDC
Testing is still in the early stages, but promising results are expected. In discussing disposable masks, technically called filtering facepiece respirators, or FFRs, the CDC discusses decontaminating them and advises that “Because ultraviolet germicidal irradiation (UVGI) vaporous hydrogen peroxide (VHP), and moist heat showed the most promise as potential methods to decontaminate FFRs, researchers, decontamination companies, healthcare systems, or individual hospitals should focus current efforts on these technologies.”
This video shows an interview with the CEO of Xenex, a manufacturer of UVGI lights. It discusses how it is being used in hospitals for sanitizing and disinfecting purposes.
What Kind of UV Light is Used in HVAC Systems?
The UV lights installed in HVAC systems are Ultraviolet germicidal irradiation lights, the kind being used to kill COVID-19 in tests being conducted.
The CDC warns that lights are more or less effective based on their UV intensity and the amount of time the contaminated surface is exposed to the light.
Since HVAC UV germicidal irradiation lights are on full-time in most cases, the dose is considered quite high.
Promising but not Proven
Tests are ongoing. While it appears that UV lights kill coronavirus, remember that intensity and dose are different for each light.
We recommend that you don’t take your health safety for granted. If you are concerned about potential contamination in your home, clean affected surfaces thoroughly. You might also want to open windows for fresh air unless you believe there is a threat immediately outside your window, which would be rare.
And consider having a UV germicidal light added to your system. If you already have one, make sure the bulb is working.
Fresh-Aire is a leading manufacturer of whole-house UV germicidal lights and other technologies. It claims that, “Fresh-Aire UV systems are tested and validated against bacteria, viruses, mold & fungus…and achieve up to a 99.999% reduction on microorganisms.”
Here is the latest update from Fresh-Aire.
Bookmark this PickHVAC page because we will continue to update this section as relevant testing data becomes available.
UV Light Options for your HVAC System
Two types of UV lights are made for sanitizing your heating and air conditioning system. They have various names including purifying lights, germicidal lights, sanitizing lights and sterilization lights.
Coil Sanitizing Lights:
If you have central air conditioning, then you have an indoor coil. It is a prime location for the development of mold and bacteria. Why?
Because the coil is used to condense moisture from the air to dehumidify your home during AC cycles. As air passes over the coil, dirt, pet dander and other debris stick to its wet surface. The combination creates an ideal setting for the growth of mold and bacteria that can be spread through your home in the passing air.
Coil UV lights are the most common HVAC sterilizing lights. Single-lamp and dual-lamp models are produced. Coil sterilization lights are installed where they can shine directly onto the surface of the coil, and they are left on continuously.
Air Sanitizing Lights:
This type of HVAC germicidal lights are installed in the ductwork bringing return air to the system. Their purpose is to kill airborne germs and mold. Stick and U-shaped lamps are used by various manufacturers.
Some air germicidal HVAC lights are coordinated with the blower motor to turn on and off as it does. These must be hardwired with the system, so installation cost is on the high end of the spectrum.