Action Air Conditioning & Refrigeration · Clearwater, Florida · CAC1818409
Is your ductwork big enough to breathe?
Undersized return ducts are the most common defect we measure in Florida homes.
A restricted return doesn't just move less air — it pulls harder, drawing hot attic air through
every leak in the system. Move the slider to your system size and see what it needs.
22.533.544.55
Which duct are you checking?
Airflow the system is set up for
In a humid climate the lower airflow removes more moisture, because the coil
runs colder. Most Florida systems should sit near 350. If you don't know, leave it there.
Drawn to scale — area is what moves air, not diameter
Required size
16″ round
Pick your installed size above to compare.
Airflow needed
1050
CFM
Required diameter
16″
round, fully extended flex
Air speed
640
feet per minute
Two-return option
2 × 12″
instead of one large duct
Quick reference
Minimum round flexible duct, fully extended, R-8, for a 25-foot run.
Your selection is highlighted.
System
CFM at 350
Return at 350
CFM at 400
Return at 400
Two returns at 400
Supply trunk at 400
Numbers close, or not close at all? Either way the only way to know what your
system is actually doing is to measure it — static pressure, delivered airflow, and moisture
removal. That's what we do on every visit.