What to know
What is demonstrable
- Accumulation narrows the effective size of a run, and a narrower run moves less air.
- The return side collects fastest, and it is the half the whole system depends on.
- Debris that is actually released into rooms from the registers is a real and visible problem.
- Vermin in ductwork is a specific finding with obvious consequences.
- Where surfaces have been damp, mould growth can occur, and the EPA lists substantial visible growth as a reason to consider cleaning.
What is claimed but not established
That dirty ducts make people ill, that cleaning them relieves symptoms, or that particle levels in a home rise because of them. The EPA's guidance says duct cleaning has never been shown to prevent health problems, and that studies do not conclusively show household particle levels increase because of dirty ducts.
It also points out that much of the material in ductwork adheres to the duct surfaces rather than entering the living space, which is the detail most advertising leaves out.
Why we tell you the unhelpful version
Because the mechanical case is strong enough on its own, and because a company that overstates the health case is a company you cannot trust on anything else it tells you about your house.
If somebody has told you your ducts are making your family ill, ask them how they know. The answer is worth hearing.
What is genuinely worth acting on
- Visible debris arriving from the registers.
- Airflow that has dropped and stayed down after a filter change.
- Construction or remodelling work in the house.
- Substantial visible growth on hard duct surfaces.
- Evidence of vermin.
Where to start
What is in your system, and whether anything needs doing about it, is a question about your house rather than about houses in general.
Our inspection is free. We will show you what we find, and if the answer is that nothing needs doing yet, that is what you will hear.