An installation that achieves the most effectiveness takes some planning. The goals and the circumstances surrounding the particular installation site both should be considered. The illustration below shows some options for placement of lamps. If allergy symptom reduction is a goal, particularly mold sensitivity, installation on the cool air supply side of the coil is the probable best choice.

Many installations utilize 2-lamp systems to more completely treat an HVAC system. If the goal is to minimize airborne microbes, optimized airstream treatment may be called for. In this case, placement in the return may be the best approach. We recommend installation by an HVAC professional -- who will be able to best evaluate the system with your goals in mind.