UV lights for air conditioners and furnaces are one of the most under-utilized additions to HVAC systems. Most of us are primarily looking for the best HVAC UV lights for air conditioners to prevent mold infection (black mold is especially problematic), bacteria spreading, and so on. In actuality, that’s only a secondary advantage of UV lights for HVAC.
What is the main reason to install UV lights inside our air conditioners and furnaces?
9 out of 10 HVAC UV lights are installed to maintain the coil’s heat-exchange capabilities. According to Air Conditioning, Heating, And Refrigeration News, the primary reason to use lights in HVAC systems is the “ability of ultraviolet light to slash 10 to 35% of HVAC energy”.
In short, to keep air conditioners energy-efficient. A 16 SEER unit can, after 5-10 years, turn into a 13 SEER unit. You can read more about SEER rating savings here.
- Your AC energy efficiency today: 16 SEER.
- Your AC energy efficiency in 10 years: 13 SEER? This would be a 19% lower efficiency. If your monthly electrical bill is $100, it can be $119 due to lower cooling coil performance.
This is because air conditioners are a perfect breeding ground for mold and bacteria, which in turn create an organic material that accumulates on our air handler’s coil. Obviously, that air handler will also blow residual mold and bacteria throughout our house.
To prevent the loss of energy efficiency and the inconvenient spread of mold, we in HVAC use UV lights. Ultraviolet light (UV-C, to be specific, with 254-nanometer wavelength) the most effective way to prevent mold and bacteria buildup on:
- Cooling coils.
- Duct surfaces.
- Air filters.
- Drain pans.
Essentially, this 254 nm UV-C light destroys mold and prevents the negative consequences of mold growth including mold spreading, “dirty coils”, loss of energy efficiency, and so on.
Before we check which particular UV lights currently on the market are the best for HVAC (air conditioners, furnaces, etc.), let’s educate ourselves a bit about UV lights. If, however, you’re in a hurry, just can jump to the comparison of the best UV lights for HVAC by clicking here:
Here are the basics that we’ll cover:
- What are the benefits of installing UV lights in your HVAC system? We’ll also explain the “dirty coils problem” using a simple ASHRAE equation for AC capacity (Capacity = CFM * 4.5 * (h1 – h2)).
- How UV-C light is used to eliminate mold and bacteria buildup in HVAC ducts and AC and furnace filters.
- What to look for in HVAC UV lights? We’ll see how you can pick the best UV lights for air conditioners and furnaces by checking the total input wattage, bulb length, and ease of installation.
In the 2nd part, we rounded up the most popular and best UV lights for HVAC, compared them, and reviewed them. There is quite a lot of differences between the best UV lights for AC units and furnaces and the ‘not so good ones’ with below 15 input watts and below 6-inch bulbs.
Let’s start with pointing clear advantages of using UV lights in your HVAC system bring:
Key Benefits Of Using UV Lights In HVAC (Direct And Indirect)
This is the direct consequence. Nobody really likes mold spores blowing all across their house every time you turn on your air conditioner. In fact, if you check the filters, you might even see the black mold forming on them, and sometimes we can also notice mold forming on the cooling coils themselves.
ASHRAE explains the benefits of using UV lights to prevent mold buildup in some detail. In their 2011 Handbook, the ASHRAE’s assembled committee has summarized the full advantages of using UV-C lights in this way (Chapter 60.8):
- UV lights “eliminate mold and bacteria”. Mold can cause pricy-to-get-rid-off mold infestation (you can read our article about how to check if you already have mold infestation here). Bacteria can cause all kinds of allergic reactions, and can even be considered a pathogen.
- UV lights “reduce and/or eliminate coil cleaning”. The main reason why we clean coils are due to the accumulation of organic matter. With UV lights, there is no mold or bacteria, hence there is no organic matter, and you can save yourself the job of cleaning the cooling coils in indoor units.
- UV lights help to “sustain coil performance”. This is the key advantage; the energy efficiency of every air conditioner depends on how well the cooling coil performs. If the biofilm from mold and bacteria accumulates on the coil, the coil performance is decreased, and other parts of AC will be under bigger-than-standard stress. This can lead to higher electricity bills and AC failures.
The 4th benefit of using UV lights in an HVAC system that ASHRAE points out is the consequence of the first 3 benefits, and it states:
“Use of UV-C can increase airflow and heat transfer coefficient and reduce both fan and refrigeration system energy use.” (ASHRAE 2011 Handbook, Chapter 60.8)
Cleaning the coils and installing UV lights can even bring back the original energy efficiency of air conditioners (that means the AC can be 10-35% more energy efficient).
The UV levels to achieve these benefits are quite small. These advantages can be achieved by striking the surface of coils by as little as 50-100 µW/cm2.
That means that a 1 W HVAC UV light bulb has the capability (in theory) to destroy germs in 10,000-20,000 cm2. That’s about 1,550 square inches of surface area.
The best UV lights for HVAC have 15+ W of power. The single best unit you can see in the table below – the #1 OdorStop OS144PRO – can generate as much as 36 W of power.
All that power goes into creating ultraviolet light which, in turn, eliminates mold. Let’s look at how UV light can eliminate germs like mold and bacteria:
How Do UV Lights In HVAC Work To Eliminate Germs?
UV-C light is widely known to be ‘germicidal‘. That means that it either kills or inactivated microorganisms. Ultraviolet has been used in medical sanitation and sterile work facilities for about 100 years now (UVGI disinfection).
This 254-nanometer short-wavelength interacts with nucleic acids in the DNA of bacteria, mold, and other microorganisms. This disruption is so severe that the bacteria cannot perform their vital cellular actions, and which leads to germ death.
In HVAC, we usually install UV lights:
- On the indoor cooling coil (UV light for air handler). These are considered mini-split UV lights.
- In the ductwork. These are considered central air UV lights.
Before introducing UV lights, this was a perfect environment for mold and bacteria growth. Under the influence of UV lights in HVAC, these microorganisms cannot grow and their organic remains cannot mess up with our air conditioners and furnaces.
Example Of “Dirty Coils” Problem
If the mold and bacteria are allowed to grow, the organic material they create will accumulate on the cooling coils and form a harmful biofilm.
The capacity of air conditioner, for example, is thereby reduced. This is illustrated by the following equation:
Capacity = CFM * 4.5 * (h1 – h2)
Due to a biofilm-forming on the coils, the h1 – h2 difference will be smaller due to less efficient energy exchange. That means that, for the same air conditioner or furnace capacity, the airflow (CFM) will have to compensate for the reduction in heat exchange. This can lead to overuse of fan, other coils, compressors, and so on; eventually, something will break down.
How To Choose The Best HVAC Lights For Air Conditioners And Furnaces
Not all UV lights for HVAC are as well-balanced as OdorStop ones. The market of UV lights is somewhat saturated with low-quality producers that offer UV light bulbs of questionable specifications, safety measures, and lower lifespans in general.
To filter out all the ‘bad’ HVAC lights for air conditioners and furnaces, we have summarized a list of the best UV lights you can currently get for your HVAC system.
Specification-wise, there are 3 key specs to check out before you buy any UV light for HVAC. These include:
- UV light input power. The higher the wattage, the better the UV light bulb. Light bulbs with below 15 W input power are considered to be less effective than 15+ W bulbs. When picking the best UV light for your specific HVAC system, make sure that it has adequately high wattage.
- UV light bulb length. The effectiveness of UV lights depends on the total surface area of the bulb. In practice, the longer the bulb, the better. Below 8-inch bulbs are considered less than perfect; in many cases, you will find UV lights with several 8-inch bulbs in order to boost bulb surface area. However, the best bulbs are the ones with 12+ inch length. Those can be single bulbs or double bulbs; the whole point is that they have an adequately high surface area to radiate UV light on every part of the coil.
- How easy it is to install UV light bulbs near the indoor air handler’s coil or in the ductwork. On average, UV bulbs are not the easiest AC or furnace accessory to install. The better ones have an easy installation process; if you’re a DIY enthusiast, you can even manage the UV light install yourself. In practice, it’s easier to install UV lights in the ductworks than near the indoor cooling coil.
Here is an example of how UV light installation into ductwork goes:
Best UV Lights For HVAC In 2023
1. Best And Most Powerful UV Light For HVAC: OdorStop OS144PRO
|16″ (12″ also available)
|254 nanometers (UV-C)
|Ease Of Installation:
OdorStop makes the best UV lights for mini-split ACs, central air units, and furnaces. All of their lights have 12+ inch light bulbs and the highest input wattage. Overall the best OdorStop UV light is the OdorStop OS144PRO; which also makes it the best HVAC UV light currently on the market.
OdorStop OS144PRO features 4 16-inch bulbs. Each of them is has a rated input power of 36 W. Combined, they have a 144 W total wattage. That is far beyond what any other UV lights are capable of achieving.
Here are two benchmark specification that makes OdorStop OS144PRO is the best overall choice for UV lights for any kind of HVAC unit (central air, mini-split, furnaces):
- Each UV light bulb is extremely powerful (36 W) and has a way above average bulb length (16″).
- There are 4 of them.
On top of that, you get all the advantages OdorStop UV lights have. This includes the energy-saving airflow sensor that turns the UV light on only when the HVAC system is actually running. Another nice thing is a LED indicator that tells you if everything is OK with the bulbs (green light).
The only back draw of all OdorStop is a higher price. This is the best brand of UV lights, and the price is quite justified, considering the input wattage and bulb length. Keep the energy efficiency (SEER rating, HSPF rating) of air conditioners, heat pumps, and furnaces will reduce the expected electricity costs and the OdorStop pay for themselves in HVAC energy savings.
All in all, OdorStop is the best and most well-known brand in UV HVAC lights. Their OdorStop OS144PRO UV lights can eliminate mold even in the biggest 5-ton, or 60,000 BTU unit:
2. Most Popular Choice For UV Light For Air Conditioners: REKO Lighting R2000
|254 nanometers (UV-C)
|Ease Of Installation:
REKO Lightning R2000 is one of the most popular UV lights on the HVAC market. This is a universal UV light for ductwork; you can protect the effectiveness of your air conditioner as well as furnaces in the simplest possible way. With a price tag of below $100, REKO Lightning R2000 is one of the cheapest UV lights for HVAC on the market (among the good ones).
R2000 is a double bulb system with 8″ bulbs that radiate 254 nanometer UV-C light. Combined, they have a net input wattage of 18 W.
Two bulbs are used to maximize the surface area of the bulbs, and therefore maximize the radiation surface. In simplified terms, the two 8″ bulbs have equal UV-C radiation as one 16″ bulb (with 18 W power).
Having 8″ bulbs has its advantages, especially as far as installation is concerned. It’s easier to install shorter bulbs into existing ductwork. If you have big ducks, you won’t have problems installing 16″ UV light bulbs. Most households with 2-5 ton units or 30,000-90,000 BTU furnaces will much more easily fit two 8″ bulbs into the ductwork; that’s why REKO Lightning R2000 is so widely used and popular.
These are UV lights for less than $100 which makes them the most affordable choice. It’s practically impossible to find the cheapest UV lights for HVAC with the same specification and reliability.
All in all, REKO Lightning R2000 UV lights for air conditioners and furnaces are one of the most popular UV lights on the market. They are easy to install, have great wattage/bulb surface area specs, and are available for less than $100:
3. Top-Rated Ultraviolet Light For AC Units: D200 UV Lights
|254 nanometers (UV-C)
|Ease Of Installation:
D200 UV is another popular top-rated UV light for HVAC. They have pretty much the same specifications as REKO Lightning R2000 UV lights and are available at a similar around $100 price point.
The dual-bulb system is well-optimized for energy savings as well as maximum radiation coverage. Two 8″ bulbs radiate UV-C light (wavelength of 254 nm) both up and down the ductwork. Because they are standard-length (8″), the D200 UV lights are also easy to install in the standard ductwork.
Available at about $100, D200 UV is quite a similar choice as REKO Lightning R2000. Honestly, there is minimal difference between the two UV lights specs-wise, with REKO being the first ones on the market and D200 UV lights trying to catch up:
4. UV Light For HVAC With The Longest Bulb (17″): Bio Shield 50-BUVAS-E UV-C
|254 nanometers (UV-C)
|Ease Of Installation:
The surface area available for UV-C radiation is essential for good HVAC UV lights. Most UV light producers use more than 1 shorter bulb to get that surface area. Bio Shield 50-BUVAS-E UV-C lights are designed completely in reverse: they include a single 17″ light bulb.
17″ UV light bulb is the single longest bulb to be installed into HVAC ductwork. Using that, the Bio Shield 50-BUVAS-E UV-C bulb has the biggest surface area available for UV radiation.
That’s why it’s highly effective directly against mold and bacteria growth, and, as a consequence, prevents organic biofilm to start accumulating on the cooling coils (which would lead to a reduction in heat-exchange efficiency, and higher electricity bills).
Because it’s longer, the Bio Shield 50-BUVAS-E UV-C isn’t as easy to install. You have to place it carefully into the ductwork.
All in all, the Bio Shield 50-BUVAS-E UV-C has the longest light bulb that can produce above-average 25 W of power:
This is about it on UV-C lights for HVAC. Essentially, they are one of the most underutilized HVAC accessories. We are all concerned about mold and keeping energy efficiency; HVAC lights can help us with both of these issues.