In general, there are two types of central AC UV light systems: coil sterilization and air sterilization. Although both work in similar ways, these two systems have different purposes.
Ultraviolet germicidal irradiation (UVGI) is proven effective to inactivate many kinds of pathogens by penetrating their cells and destroying the DNA. This technology is commonly applied in sterilization lamps or planted in air purifiers. You can also have the system installed in your central HVAC system.
Besides removing the excess heat, your air conditioning system also strips the excess moisture from your indoor air. The water droplets stay on the coil and make the surface wet. As the air passes through, some airborne germs will stick to the wet coil and stay there.
A humid coil is a perfect place for mold to grow, which can leak and even destroy your ductwork and other parts of the system. Other germs may also grow and accumulate. As the air continues to pass through, some germs might get carried along and enter your room.
The coil-treatment UV light will focus on the coil to kill the germs on the surface. Because the targets are not moving, the radiation will have unlimited exposure time to finish its job. Moreover, the UVGI lamp can turn on continuously even if the HVAC is off.
An air-treatment UV light system usually sits near the return duct. This radiation lamp will shine on the ductwork and kill the germs carried along by the flowing air that is about to enter your room. As a result, your indoor air will contain significantly fewer germs and cause fewer health problems for your family.
This type of UVGI lamp has a remarkably short time to sterilize all the germs because the air is on the move during the process. Meanwhile, exposure duration is essential to disinfect the germs effectively. Hence, this purifying system should have high-intensity UV radiation. Sizing can be crucial when you decide to install this system in your house.
Which Type is Best?
The best type for your house depends on your purpose for the radiation lamp. If you expect significantly better IAQ (indoor air quality), a coil purification system may be disappointing for you. On the contrary, if you hope to lower the risk of HVAC damage, an air purification system will not be effective.
A coil sterilization system will also contribute to better IAQ. But this is limited to only eliminating the pollutants on the coil. On the other hand, air sterilization UVGI can also maintain your HVAC performance because there will be fewer particles blocking the system. However, the effect will not be significant.
Both AC UV light systems can be beneficial or practical, depending on your situation and needs. You just need to choose the most suitable one for your house. Besides that, you also need to make sure that the unit you buy has the right level of intensity for the size of your room.