What a NADCA-Standard Cleaning Involves

The standard, briefly

The National Air Duct Cleaners Association publishes ACR, the standard for assessing, cleaning and restoring HVAC systems. It is the document the EPA points homeowners toward. Its central idea is source removal: dirt is mechanically dislodged and captured, so the system is actually cleaner afterwards, rather than sprayed, coated or blown into the house.

The steps, in order

Inspection

Before anything is cleaned, the system is looked at: the air handler, a return, several supplies, and the attic runs. This is where a Tampa inspection differs from one in a dry climate, because it should include looking for condensation, wet insulation and a clogged drain line.

Containment and negative pressure

A vacuum collection unit is attached to the trunk and run so the whole system is under suction. Registers are sealed as work moves through the house. Air leaving the collector goes outside, or through a HEPA filter if the unit is inside.

Agitation of every run

Every supply and every return is worked with tools suited to the duct: brushes for metal, air whips and soft brushes for flex and duct board. The tool goes all the way to the trunk.

The air handler

The blower assembly, cabinet, drain pan and, where the company is licensed for it, the coil. Florida law treats duct cleaning that requires partial disassembly of the system as work for a licensed air-conditioning, mechanical or sheet metal contractor.

Verification

Visual inspection afterwards, ideally with photos or video from inside the ducts that you can compare with the ones taken at the start.

What the standard does not require

Chemicals. Sanitizers and coatings are optional add-ons for specific reasons, applied after cleaning, with a product registered for the surface. The EPA notes that nothing is registered for use on fiberglass duct board or lined duct. If a company leads with fogging, it is leading with the least important part.

How to use this when hiring

Ask the company whether it follows ACR, and then ask what that means on the day. Listen for negative pressure, every run, the air handler, and photos. NADCA also certifies individual technicians as Air Systems Cleaning Specialists (ASCS); asking whether one will be on your job is reasonable.