Airflow verification is the step that turns cleaning from an activity into a result. Without it, a vendor leaves a property having cleaned some ducts, some of the way, and nobody — including the vendor — knows which.
What Is Being Measured
Air velocity or volume at the exterior termination with the dryer running on a heat cycle. The measurement establishes that exhaust air is actually leaving the building at a rate consistent with an unrestricted system.
Why It Matters More Than It Sounds
Consider two units on the same property, both cleaned on the same day. Unit A now exhausts freely. Unit B still shows restriction. Without airflow verification, both are marked complete and invoiced identically. With it, Unit B is immediately identified as having a physical duct problem: a crushed section, a disconnected run, a collapsed elbow, a nest further inside than the brush reached, or a duct so long it cannot move air regardless of cleanliness.
Unit B is the unit that catches fire. The cleaning did not fail — the duct is broken. Verification is how you find out.
What Restricted Airflow After Cleaning Tells You
- Crushed or kinked duct — often behind or beneath the appliance, or where a duct passes through framing
- Disconnected run — the duct terminates in a wall cavity or ceiling space and the exhaust is not leaving the building at all
- Excessive developed length — the run is longer than the code permits and simply cannot move sufficient air
- Failed damper — the flap is not opening
- Obstruction beyond brush reach — nesting or debris deeper than the cleaning reached
Each of these is a deficiency-report item with a specific remedy. None of them is fixed by cleaning again.
The Disconnected Duct Problem
This deserves separate mention. A duct that has come apart inside a wall or ceiling vents hot, moist, lint-laden air directly into the building structure. It builds moisture in insulation, deposits lint in the cavity, and — if it happens above a ceiling — accumulates fuel in exactly the space fire spreads through. Residents often report no problem at all, because their dryer works fine. Only airflow measurement at the termination reveals that nothing is coming out.
What to Ask Your Vendor
“Do you verify airflow at every unit after cleaning, and does the report show it?” A vendor who verifies by exception — only where the technician suspects a problem — is relying on suspicion where a measurement was available.
What We Do
Airflow is verified at every unit. Restricted units after cleaning are photographed, logged, and cross-referenced to the deficiency report with a specific probable cause and recommended remedy. Your maintenance team receives a punch list, not a mystery.