The idea of killing off the germs in your home just by shining a light into your air ducts admittedly sounds a little too good to be true, but HVAC UV lights really can improve your home’s air quality. In fact, these lights have been used for decades in hospitals and other facilities where sanitation is critical.
Even so, purifying your home’s air with UV lights isn’t as simple as some manufacturers might make it seem and not every home really needs one of these systems.
How UV Lights Clean the Air
Ultraviolet (UV) lights for HVAC systems are commonly known as ultraviolet germicidal irradiation (UVGI) systems. They target a very specific type of air contaminant, namely microorganisms such as bacteria, viruses, and mold spores. You might be familiar with the way hanging laundry out in the sunshine helps kill any germs or mold clinging to it. UV lights work in essentially the same way.
UVGI systems produce the same kind of ultraviolet light that’s present in sunshine, but at a much higher intensity than found in the sunshine that reaches the earth. This light destroys microorganisms’ nucleic acids, damaging their DNA and either killing them or leaving them unable to reproduce.
The light affects only living microorganisms, meaning these systems can’t control dust, pollen, pet dander or other particles that aren’t alive. Gaseous pollutants, such as cooking fumes and volatile organic compounds (VOCs), aren’t affected, either.
UV light’s ability to kill pathogens in water and air was scientifically proven early in the 20th century. These systems have been used in hospitals as far back as the 1930s to reduce the spread of diseases such as measles and tuberculosis.
They’re now known to be effective against virus types such as rhinoviruses (common cold), influenza viruses (flu), and Severe Acute Respiratory Syndrome (SARS) and against bacteria such as Staphylococcus aureus (Staph infection) and Streptococcus variants.
The benefits are widely accepted and thousands of water treatment plants, hospitals, and food handling facilities across the country use UVGI systems as part of their efforts to minimize contamination.
Not All UVGI Systems Work the Same
All that said, cleaning your home’s air isn’t as simple as sticking any UVGI air purifier you find into your HVAC ducts. To be killed or neutralized, microorganisms must be exposed to the right kind of light for the right amount of time. A UV system’s effectiveness in a given situation depends on several factors, including:
- Lamp wavelength and intensity
- Number of lamps
- Lamp position
- Duct reflectivity
In addition, before you start looking for an HVAC UV light system, you’ll need to choose which of the two types available are right for your needs.
Coil Sterilization – This is the most common type. It’s installed near the air conditioner’s indoor evaporator coil and shines constantly to prevent mold and bacteria from building up on or around the coil. Less mold and microbes on your coil means less in your air.
Air Sterilization – This system is specifically designed to kill microbes in your air. It’s usually installed in the return air duct and turns on only when the heating or cooling system is running. Because it purifies all the air passing through, it also reduces the risk of microbial buildup on your HVAC components, such as your evaporator coil, air ducts, air filter, and drain pan.
When a UV Air Purifier is Worth the Investment
While these systems do provide benefits, they’re not cheap, and they require annual maintenance, which includes replacing the pricey lamps. The lamps lose power over the course of a year or two and eventually become ineffective at killing germs, even though they still produce visible light.
Before you invest in a UVGI system, consider whether or not your household has air quality needs that this air purification method can meet effectively.
If someone in your home is managing a respiratory condition, such as asthma, allergies or chronic obstructive pulmonary disease (COPD) or has a weakened immune system, any additional air purification can pay off. This is especially true of UV air purifiers, which target disease-causing microbes, not just irritants such as dust and pollen.
In a humid climate, your evaporator coil is at a greater-than-average risk of getting wet and developing mold. A UVGI system reduces the amount of active mold spores on the coil and in the air.
UVGI systems tend to provide greater benefits in more crowded conditions. Installing one of these systems might be a good idea if you have a large family in a small house or even if you enjoy filling your home with guests during the autumn and winter holidays, which also happens to be the height of cold and flu season.
Because it controls a limited range of contaminants, a UVGI system alone isn’t enough to keep your home’s air clean. You’ll still need a higher-efficiency air filter to trap the smaller particles of dust, pollen, and other pollutants that can aggravate allergies and asthma.
If you’re considering having an HVAC UV light installed, talk with a heating and cooling technician first. A professional will be able to advise you on which type of system will do the best job of purifying your home’s air.