February 28, 2020
HVAC UV Lights – How do they work?
UV AC LIghts

HVAC UV Lights – How do they work?

Let’s be honest, you never think about cleaning your HVAC system. It exists in your home and you know it controls your air. But the air in your home is constantly recirculating through the same duct system. A buildup of microbes in your home is inevitable. Most of us do not even think about the quality of the air in our homes. But more toxins, bacteria, fungi, and mold sneak in from outside than you might think. All these things can compromise the air you’re breathing in your home right now.
It can be tricky finding a way to purify the air in your home. Ultraviolet sterilization is an option to improve the quality of your air.
But how do you know if you need this service? And more importantly, how can you agree to a service if you don’t know what it does? To understand what ultraviolet sterilization is, we need to break it down. Let’s look at it in two pieces. We will define ultraviolet first and sterilization second. Then, we will look at how these two things work together. Finally, we will talk about how McCarthy Air can help you decide if you need this service.

What is “ultraviolet”?

Ultraviolet, or UV, is a type of light ray. You might be familiar with it already thanks to sunscreen. Sunscreen bottles often boast SPF (sun protection factor) scores. These SPF numbers show how much protection from UV(B) rays that sunscreen offers. But what is a UV ray?
First, let’s take a step back. All light exists on a spectrum. It is the electromagnetic spectrum.
Imagine you are holding a bucket with a hole in the bottom. The bucket is hanging by a string and is full of water. Sway the bucket side to side. Now walk fast and then slow. If you look back at the water that fell out of the bucket you will see a wavy line. The first half of the waves should be close together. The second half of the waves should be far apart. This is what the electromagnetic spectrum looks like.

Electromagnetic Spectrum

The left side of the spectrum is for light with short wavelengths. The right side of the spectrum is for light with long wavelengths. A wavelength is the distance between two crests or two troughs. A crest is the top of the wavelength. A trough is the bottom of the wavelength.
The closer the waves are together, the smaller the wavelength. The further apart they are, the longer the wavelength.
The electromagnetic spectrum also deals with the frequency of light. Frequency measures how many wavelengths are happening each second. High frequency rays are on the left side and low frequency rays on the right side. This means light with a long wavelength has a high frequency. Light with a short wavelength has a low frequency.
Most of the light on the spectrum is light we can not see with the naked eye. Gamma rays, x rays, and ultraviolet rays are all high frequency, short wavelength rays. They are on the left side of the spectrum. Infrared, microwaves, and radio waves are all low frequency, long wavelength rays. They are on the right side of the spectrum. We can not see any of these rays without special equipment or lights.
In the middle of the spectrum is a small section of visible light. This section is the one you are most likely to be familiar with. When you think of visible light, think of a rainbow. From left to right, it goes red, orange, yellow, green, blue, purple, violet. Red light travels the slowest and violet light travels the fastest. So ultraviolet light means past violet. UV light exists past violet on the spectrum.

Different types of UV Light

There are three different types of ultraviolet light. The sun emits all three UV rays into the Earth’s atmosphere.
UVA light has the longest wavelength.
UVB light has a shorter wavelength.
UVC light has the shortest wavelength. This is the type of UV light used in UV sterilization. It is the only type of ultraviolet light with a high enough energy to sterilize microbes. UVC rays are also known as germicidal UV. Germicidal means that it can kill bacteria.

What is sterilization?

At some point in your life, you have probably heard this term. Many things need sterilization before or after use.
To sterilize something is to completely remove microbes from something. Microbes can include types of bacteria, viruses, fungi, etc.
There are many types of sterilization. There are physical and chemical ways to sterilize something. Different types of physical sterilization include steam, dry heat, and radiation. Chemical sterilization is when a chemical like formaldehyde kills microbes.
The most accessible form of sterilization is boiling. Water must reach a temperature of at least 212 degrees Fahrenheit. You must boil the water for at least twenty minutes. Laboratories use something like boiling. An autoclave is a device used in labs to sterilize equipment. The autoclave looks like a bucket that opens at the top. Lab instruments go inside the autoclave. It heats water up to create extremely hot steam. That steam then kills any microbes on the instruments.
Both the autoclave method and the boiling method are physical sterilization. Ultraviolet sterilization is a type of radiation sterilization.
Ultraviolet sterilization is also effective in sterilizing water.

How does ultraviolet light sterilize something?

We install several lights in your ducts and around your AC coil. There is also a fan involved in installation. This fan helps to move air past the lights. Moving air allows for the microbes to pass by the lights more often and increases efficacy.
The lights use UVC light to kill any microbes in your AC system. It kills any bacteria, viruses, mold, or fungi that may be present. UVC light has a short wavelength and a high frequency. This means it has a lot of waves that move very fast.
The frequency of the UVC light is higher than the frequency of the microbes. The difference in frequency is what allows UVC light to sterilize. The high frequency vibrates and acts like an earthquake. These vibrations jumble the genetic makeup of the microbes. This process makes it difficult for the microbe to create more of itself. It also breaks down the original microbe. This effectively kills it.

Isn’t this what air purifiers do?

The quick answer to that is no. Air purifiers and UV sterilization are completely different. An air purifier removes toxins and allergens from the air. Those particles and microbes are then trapped in a filter. They may be out of your air, but they aren’t gone. They sit in the filter and in your purifier until you change the filter. You still have the hassle of removing and replacing the filter. That’s an extra cost and an extra maintenance step.
UV sterilization does more than remove microbes from the air and put it somewhere else. It eradicates the existing microbes. Ultraviolet sterilization also prevents them from multiplying.
Air purifiers are also only good for small areas. They are often not made to clean an entire home or business. But UV sterilization can increase the quality of your air in any setting. The UVC lights are only placed in a few select areas and the fan does the rest. Once the air is circulating past the lights consistently, the rest is a breeze.

How long does it take?

How long it takes to sterilize your duct system can vary. It depends on a few deciding factors. If your system is heavily contaminated it will take longer to sterilize. Also, the bigger your system, the longer it will take. Installing lights can be tricky because the UV exposure to the microbes has to be direct. Direct exposure is necessary for UV sterilization to work. This means more ductwork equals more lights and more time.

How do you tell if your HVAC system needs UV sterilization?

Microbes exist in an invisible world. Unless there is a mold or fungus growth, you don’t see microbes. So how do you know if your system needs UV sterilization? The short answer is to call us at McCarthy Air Conditioning. We can come out and do an inspection. After completing the inspection, we can recommend a course of action.
UV sterilization is great for treating existing problems. But it’s best for prevention.
For more information on ultraviolet sterilization, call McCarthy Air Conditioning today. We are available for any questions you may have.
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Published: February 28, 2020
Author: suiteedge
Categories : Air Purification