Are you considering having a UV light installed to improve your indoor air quality or prevent biological growth (including mold) in your HVAC system? Read more to find out the truth about UV air purification and what you need to know before you spend your hard-earned money.
UV purification is widely misunderstood, and we hear of this misconception on a regular basis. Contractors and technicians assume that a UV light located in the air stream or near the evaporator coil will purify the air, but this is simply not true. UV light will only disinfect the surfaces where the light shines and putting one in your system can actually damage your equipment. Let’s look at both of these important factors.
- UV light degrades plastics through Photodegradation and the photostabilization of polymers.(1)
Very few indoor units are designed to withstand exposure to UV, and only recently have more manufacturers started to address this issue. The reason this is a problem is the drain pan (the thing that collects water from your evaporator coil) is almost always going to be made of plastic which can crack if exposed to UV. If a crack develops in the pan your home and equipment can be damaged. Granted, it will take 3 to 5 years of exposure before the cracks develop and by then, who is going to think that it was the light installed years ago that caused the problem. So, you end up replacing your drain pan, probably a new UV light since they last about a year, and rinse and repeat. Talk about a stable source of income! Man, I love this trade! I’m kidding, we won’t install this type of UV light.
- The further away the light is from the coil, the less effective it will be.
Since UV lights are only effective on the surfaces where the light shines, in order for it to reduce biological growth on your coil it will need to be installed as close as possible to the coil. The only way to prevent damage to the drain pan and other susceptible components is to install a shield around or over them, which is not going to be easily accomplished, if possible at all.
This brings us to the second factor to consider. Since UV light is only effective on the surface areas where it strikes, you will likely need to have one installed on both sides of your evaporator coil to prevent biological growth. Even still, some coils have more than just 2 sides, shaped like the letter N or W and could require more than 2 lights to reach every part of the coil.
So what’s the answer? There’s 2. First let’s consider what’s really going on. Why do you want a UV light? Is it biological growth on your coil, or to disinfect the air? If the purpose is to prevent biological growth, then you are barking up the wrong tree. In order to thrive, biological growths need moisture and the evaporator coil is the perfect place for it, if it isn’t working properly. You see, the coil should not be holding water, it should be removing water through the drain. If the moisture levels are high enough to encourage biological growth, then something else isn’t right. It could be the system is too large for the home or building, the filters are not being changed often enough, the static pressure of the air is too high, the drain line is clogged or there is outdoor air making its way into your duct system. Most often it is a combination of several factors.
To summarize, reduce the moisture content in the air by having a properly sized and sealed system, perform thorough and regular maintenance and make sure the drain line stays clear.
- If your desired purpose for the UV light is to disinfect the air, then you need to look for a system capable of producing an oxidizing plasma also called photo-hydro-ionization.
Photo-hydro-ionization is a process first used commercially by the RFG environmental group. https://www.rgf.com. When the HVAC system is in operation, the unit creates an advanced oxidation plasma (AOP) that is distributed through the duct system into the conditioning living space, all the way back to the evaporator coil. Unlike passive air technologies, such as an electrostatic filters, which need pollutants to pass through the unit for purification or filtration, the AOP sweeps through the home or building actively purifying pollutants at the source. The AOP consists of hydro-peroxides, oxide ions and hydroxide ions which are all friendly oxidizers that are found in nature’s process of cleaning the outdoor air and are safe for humans and animals alike.
RGF’s systems produce this oxidizing plasma as a small UV light shines on a metal that acts as a catalyst. The plasma that is created travels throughout the entire envelope of the home or building and effectively disinfects the air as well as surfaces. These units are much more expensive than a conventional UV bulb, but they are truly superior and in a league of their own.
The Guardian Air QR+ utilizes RGF’s patented PHI-Cell® technology and is easily mounted into an existing air conditioning and heating system’s air ducts.
These units are air purifiers and not filters. It does not reduce particulate matter like dust. For an air purifier with added particulate reduction that is even more effective at removing allergens, you’ll want to have a look at the REME HALO®.
Again, you must consider why you want this unit and if it is truly worth the cost to you. If you are suffering from health issues that you suspect are related to your indoor air I will recommend the same thing I always recommend to our customers. Talk to a practitioner about exercise, eating habits, gut flora, lifestyle changes, getting more fresh air and having some tests done to see what you are possibly reacting to. Hopes deferred make the heart sick and I don’t ever want to tell our customers that we have the answer when we truly don’t know what the real problems are. I work on HVAC equipment, not people.