The dust goes into the machine
Safe duct cleaning starts with suction, not a brush in a vent. Dust sitting in a supply is stuck until something knocks it loose. The second a brush or air whip hits that surface, the particles are airborne inside the duct. If registers are uncovered and nothing is pulling, that cloud takes the easiest path out — usually the nearest grille.
Before anyone agitates, the crew connects a HEPA-filtered negative-air machine and seals the other openings so air can only move toward that machine. NADCA calls this source removal: knock the debris loose and extract it at the same time. Truck-mounted units and high-capacity portables both work when they are sized to hold suction through your runs. The test is whether negative pressure holds while the brushes work.
A typical HEPA filter is specified to capture 99.97% of particles at 0.3 microns, which is why the machine can move a lot of air without dumping the dirt back into the rooms. If the vacuum isn't holding, agitation is just relocation.
Registers that aren't being worked get covered. The old filter comes out. Then the collection hose goes on. In a CBS two-story toward Lake Nona the handler is often on a tight attic platform — summer attics here commonly hit 130–150°F — and the hose run is longer.
Agitation starts at the farthest supply and return and works back toward the machine. Leave a caked blower upstream and the trunks reload the next time the fan runs. Every opening cut for access gets closed with mastic, foil tape, or a real access panel. A rectangle of cloth duct tape on the plenum is the leftover you can check with a flashlight.
The tool has to match the duct
Rigid metal can take a firmer rotary brush. Flex — the insulated tube in most Orlando attics — needs a softer nylon head or a pneumatic whip. A stiff spinning brush will tear the inner liner or knock the spiral wire out of shape. Ductboard collapses if you lean on it. Heat-aged flex on 1990s–early-2000s systems is more brittle after years in that attic.
When you should skip the job
Change the filter yourself if that is the only dirt you can find. Wipe the register covers. Bringing a crew over for that doesn't make sense unless you want a free inspection of everything else.
If the smell is a musty puff for half a minute when the AC first kicks on, then fades, look at the indoor coil and drain pan.
If the ducts were done a couple of years ago and the vents look fine, wait. EPA guidance is that benefits are situational — visible debris, renovation dust, a real reason.
Do not DIY the trunks with a shop-vac or a leaf blower. You can wipe grilles. Full trunks need a collection machine that holds the system under suction. If water has been in the ducts, leave the system off and call us to get it assessed.
Frequently Asked Questions
Do I need to leave during the cleaning?
Usually no. Keep kids and pets out of the work area around the air handler, and stay off the attic platform. If you are highly dust-sensitive, spending the agitation pass in another part of the house is a comfort call, but not a requirement.
Do they spray chemicals in the ducts?
The cleaning is done by mechanical extraction — brushes and a high-power vacuum. An EPA-registered product on non-porous surfaces is optional after the dirt is out, and only when there is a confirmed reason.
Setup, not spray
Safe duct cleaning is a setup problem. Get the vacuum on, match the tool to the air duct, close every opening you can. If that is the job you want, start at air duct cleaning. Top 1 Air Duct Cleaning does that work across Orange County on a normal schedule. Book a slot that fits.