Steril-Aire UVC Emitters Steril-Aire UVC lights are designed to mount in the HVAC system supply duct, usually right at the cooling coil. Why? To kill the mold and mildew that grows on the coil and in the drainpan, increasing the efficiency of the HVAC unit through better heat exchange and reduced pressure drop, and to clean the air as it passes by, eliminating odors and killing bacteria and viruses as they pass by.