Is Duct Cleaning Worth It? Usually Not. Here Is When It Is.

We get asked about duct cleaning a lot, usually after a flyer or a phone call offering the whole house for a suspiciously low price. Our honest answer is that in most homes it is money spent on the wrong thing. That is not because ducts are clean; it is because the dust in your house did not come from the ducts, and cleaning them does not change where it is coming from.

Where the dust actually comes from

Dust that settles on furniture is mostly generated inside the living space: skin, fabric fibres, pet dander, and whatever comes in on shoes and through open doors. The air handler pulls that air through the filter, and what the filter does not catch goes through the ducts and back into the rooms. A duct that has been carrying air for twenty years has a light coating of dust on its walls, and that coating is largely stable; air moving past it does not lift much back off.

The far bigger contributor in North Texas homes is the attic. Ducts here run through a hot, dusty attic, and a leaky return duct or a poorly sealed air handler pulls attic air, with its insulation fibres and fine dust, straight into the system. That is where a persistent dust problem usually starts, and cleaning the inside of the ducts leaves the leak that caused it exactly as it was.

When duct cleaning genuinely makes sense

• After construction or a major renovation, when drywall dust and sawdust have been pulled into the system in quantity.
• When a camera or a look inside a duct shows visible mold growth, particularly on internally lined ducts, and the moisture source has been fixed.
• When rodents or insects have been in the ducts. This calls for cleaning and, usually, sealing the openings they used.
• When a previous owner smoked heavily or kept many animals, and the smell persists after the house has been cleaned.
• When ducts are visibly clogged with debris, which almost always means they were never sealed properly and attic material has been falling in.

In each of these cases the cleaning is a response to a specific event, and it should be paired with fixing the cause.

What fixes dusty, musty air more reliably

1. Seal the return side. A return plenum or return duct leaking in the attic is the single most common source of dust and attic smell in the homes we service. Sealing it also lowers bills.
2. Upgrade the filter, within reason. A pleated filter of moderate rating catches far more than a fibreglass one. Too high a rating restricts airflow; the right answer is a larger filter area, such as a media cabinet, not a denser one-inch filter.
3. Fix the condensate drain and the coil. A musty smell when the AC runs is usually a dirty, damp evaporator coil or a slow drain pan, not the ducts.
4. Replace crushed, kinked or disconnected flex duct. A duct lying in insulation with a hole in it is both an air leak and a dust intake.
5. Address humidity. Mold in ducts needs moisture. If the house runs humid, the system may be oversized or short cycling, and that is worth diagnosing.

If you do have it done

Ask for a description of the method. Ask whether the air handler, coil and blower are included, because they hold more of the material than the ducts do. Ask whether the ducts will be sealed afterwards. And be sceptical of any finding of mold that comes without a sample or a photo of something you can see yourself. A camera inspection of the ducts before any cleaning is a reasonable request; we do it as part of a duct evaluation.

Family-owned in Rockwall, licensed and insured. TX HVAC License TACLB2360E. (469) 338-5533.