The short answer: about 2 to 4 hours per system
A thorough air duct cleaning on a single HVAC system usually runs two to four hours from setup to verification. Smaller condos and one-system homes land near the low end; larger Tampa homes with long duct runs and many registers take longer. A second system roughly doubles the time, which is why Tampa Duct Cleaners prices each system separately at a flat $624 (two systems $1,248).
That window covers more than just running a vacuum. It includes inspecting the system, sealing registers, attaching truck-mounted negative-pressure equipment, working source removal through every supply and return branch, cleaning the blower and evaporator coil area, and documenting the result. Done at NADCA standards, it simply cannot be rushed into a few minutes.
What makes one job take longer than another
Four things drive the range. System size and the number of registers: a 4-ton system feeding a dozen rooms has far more linear footage of duct than a small two-bedroom. Number of systems: each separate air handler is its own full cleaning. Level of contamination: heavy dust, biological growth, or post-renovation drywall debris all take more agitation and more passes. And access: a clean, reachable air handler in a garage goes faster than one buried in a tight attic in Florida summer heat.
Because of these variables, an honest contractor inspects first and gives you a realistic time window rather than a one-size-fits-all promise. The flat per-system pricing means the quote does not change if your ducts turn out dirtier than expected — only the time on site does.
Why 15 minutes is a red flag
The classic "$49 whole-house special" is built around speed, not cleaning. A crew that finishes in 15 to 20 minutes is typically running a shop vac over a few visible registers without continuous negative pressure or rotary source removal. Agitating ducts without proper containment can relocate dust from inside the system into your living space — leaving the air worse, not better.
Real source removal means physically dislodging debris from the duct walls while a HEPA-filtered, truck-mounted vacuum holds the entire system under negative pressure so nothing escapes into the home. That process takes time across every branch of the system. If a price or a timeline sounds too good to be true, it is.
What actually happens during those hours
A proper visit follows a clear sequence. First, a technician inspects the ductwork and air handler so you know what you are paying for. Registers and grilles are removed and the system is sealed, then connected to truck-mounted negative-pressure HEPA equipment. Using a Rotobrush rotary-brush tool, the technician works each supply and return run, mechanically breaking debris loose so the vacuum can capture it.
The blower compartment and the area around the evaporator coil get attention too, since that is where airflow and moisture concentrate biological growth in humid Florida air. Finally, the system is reassembled and you are shown before-and-after photos from inside the ducts as verification. If sanitizing or a Pure Breathe indoor-air-quality upgrade makes sense, that is quoted free in-home rather than upsold on the spot — and Hales Comfort Club members save 20% on the work.