Some companies will tell you that ducts need cleaning every year. For the average Delaware home, that is more often than necessary. Our honest recommendation, the same one we give our neighbors, is every 2 to 3 years.
Why not more often? Because a properly cleaned system stays clean for a while. When the whole system is cleaned under negative air, the supply runs, returns, registers and blower, there is no reservoir of dust left behind to blow back into the rooms. It takes time for normal household dust, dander and pollen to build back up to the point where it affects your air.
Why not less often? Because after about three years, most homes have accumulated enough buildup that the system starts recirculating it. Dust reappears faster after cleaning, musty notes show up when the blower starts, and filters clog more quickly. Those are the signs the cycle has run its course.
There are exceptions that move the schedule up. Clean sooner if you just moved in, especially into new construction. Clean sooner after any renovation, because drywall and sanding dust goes straight into the system. And clean sooner if someone in the home has asthma, bad allergies, or a compromised immune system, since the marginal dust load matters much more to them.
Pets matter too. A dog or two that shed heavily can justify moving the schedule up, since dander and hair collect in the returns. The same goes for smokers in the home, or a house that sits near a busy road or farmland where more dust and pollen comes in through normal ventilation.
Water events deserve their own mention. If you have had a flood, a roof leak, or a basement moisture problem, have the ducts inspected even if you had them cleaned recently. Moisture inside duct work can support mold growth, and no cleaning schedule applies once water is involved.
Between cleanings, the best things you can do are free: change your HVAC filter on schedule, keep supply registers vacuumed, and pay attention to musty smells or dust that returns unusually fast. Those are the signs that it is time to call. And if you are ever unsure, we will give you a straight answer about whether your home actually needs it.