Home / Services / Flex duct: clean or replace
About one McKinney house in five was built from 1980 to 1999. Where the ductwork in those houses is original, it has been in an attic for twenty-five years or more, and cleaning it is not always money well spent.
Flexible duct is a wire coil wrapped in a thin plastic liner, a layer of insulation and an outer jacket. It is light and quick to install, which is why so much of it was used. It is also less durable than sheet metal.
An unconditioned attic is hard on it. Allison Bailes of Energy Vanguard writes that on a sunny summer day the air in one "can get up to 120° F or even a bit higher." Decades of that, plus anyone who has crawled past to store boxes or run a cable, leave marks that are easy to see once you know where to look.
| What you see | What it means | Clean? |
|---|---|---|
| Jacket intact, runs pulled fairly straight | The duct is sound | Yes, if there is a reason to |
| Outer jacket torn, insulation showing | The wrap has failed in that spot and the liner is exposed | Repair or replace that run first |
| A run sagging deeply or bent sharply | Air is being choked at the bend | Re-hang or replace; cleaning will not fix airflow |
| A duct pulled off its collar | That room is being fed attic air, and dust with it | Reconnect before anything else |
| Insulation wet, stained or moldy | Water has been in or on the duct | No. Replace |
You can do this from the attic hatch with a flashlight. Do not walk on the joists to get closer; a photograph from the hatch is enough for a contractor to work from.
If the ducts pass, they are cleaned like any others, with soft tools. If some runs fail, the sensible order is to have those replaced by a licensed air conditioning contractor and then decide whether what is left needs cleaning. New runs do not.
When most of the system fails, a cleaning is the wrong purchase. Put the money toward new ductwork, which is often done along with an equipment change. The page on cleaning before an HVAC replacement covers that timing.
Sound flex duct can be cleaned with gentle tools. Duct that is torn, crushed or brittle is likely to be damaged further by cleaning, which is why it is inspected first.
Installing or replacing ducts is air conditioning contracting, so it is done by a contractor licensed by the Texas Department of Licensing and Regulation. A duct cleaning company can tell you what it found; it cannot do the replacement unless it holds that license.
Usually not. The EPA says insulated ducts whose insulation gets wet or moldy cannot be effectively cleaned and should be removed and replaced.
Take two photographs from the attic hatch and describe them on the phone or in the form.
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