Depending on the model you choose, your UV bulb may work constantly or only when the air conditioner is in operation. For example, the UV lights installed on the air controller will be on all the time, while those placed inside the ducts should only be turned on when the air conditioner is in use. Most manufacturers recommend replacing the UV lamp every 9000 hours or approximately every 12 months. An annual replacement program is also recommended for those with allergies and other respiratory conditions.
Residential systems tend to be smaller and the entire volume of air takes longer to circulate through them. These systems clean the air slowly but continuously, reducing viral and bacterial loads in indoor air over time. According to the EPA, passing all air through ultraviolet light removes approximately 99.9% of contaminants. We recommend replacing all UV bulbs every three years, no matter how often they are used.
UV HVAC lights are an effective means of improving indoor air quality, but only after following indoor air quality priorities. By preventing mold and bacteria from accumulating on wet HVAC components, UV lights can also prevent airborne biological contaminants from circulating in the indoor air of your home. When an ultraviolet light is configured to illuminate the condenser coil and drain pan, it can be quite effective in preventing mold and bacteria from flooding these parts of the system. You can add super powerful UV light to your air conditioning system, but it's probably too much and will cost you thousands and thousands of dollars.
The answer to this question depends on the type of UV light system and the volume of air that passes through it. Researchers know that the virus travels in water particles suspended in the air, so only UV lights installed in the ducts that treat the air flowing through them could be useful. This is why UV lights in your HVAC system will most likely not help prevent the spread of COVID-19. UVC air purifiers have UV lights inside their HVAC system, where light rays don't fall directly on you. And, to be fair, mold spores and bacteria from the condenser coil could reach the air supply, so these UV lights offer a very small advantage.
Finally, some HVAC technicians who work in sales rely on UV light treatment in their system because it can kill bacteria. However, it doesn't make sense to install a UV HVAC lamp unless you've followed the quality priorities of the indoor air. The coil area tends to have a lot of condensation and moisture buildup, so an ultraviolet light will prevent any mold growth in this area. But what happens after installing the UV light? How often should you change your UV bulbs? Should you wait until they burn? We recommend replacing all UV bulbs every three years, no matter how often they are used.
