Because it is where growth starts. The evaporator coil produces condensate continuously while cooling — that is how your system removes humidity — so in a Florida cooling season it stays wet for months. Dark, damp, and dusted with organic material is precisely what mould and biofilm need. Treating circulating air without addressing the coil leaves the source running.

Both, and the performance side is often overlooked. Biofilm on the coil restricts airflow across it and insulates the surface, reducing heat transfer — the same effect dirty coils have. So the system runs longer for the same result. That makes coil purification an efficiency measure as well as an air quality one.

Positioned to illuminate the coil surface directly, because UV-C only treats what it reaches. A lamp mounted where it does not actually shine on the coil is close to useless, and this is the most common installation failure with UV systems. Ask any contractor where the lamp will sit and why — a good answer describes the coil, not the cabinet.

Not quickly, and this is worth being clear about. UV-C is preventative — it controls growth over time rather than removing established buildup. Where contamination is already significant, coil cleaning comes first and purification then keeps it from returning. Installing a lamp onto a heavily fouled coil and expecting it to resolve matters would be disappointing.

Yes. UV-C lamps lose output gradually while still appearing lit, so a lamp that looks fine may have stopped doing much. Replacement intervals vary by system, and we check output and age during maintenance visits rather than leaving you to guess. It is the ongoing cost worth knowing about before you buy.

When installed correctly, yes — the lamp sits enclosed inside the air handler or ductwork, so the light is contained within the equipment and there is no exposure during normal operation. Correct electrical integration and proper enclosure are part of a professional installation, and it is one of several reasons this is not a DIY fitting.