How Often Should You Clean Air Ducts in the Pacific Northwest?

In Renton and around Puget Sound, the long gray season brings months of rain, mild temperatures and damp air. Furnaces and heat pumps run for much of the year, and late summer can bring wildfire smoke. All of that affects what builds up inside your ductwork. So how often should the ducts be cleaned?

The short answer: every 3 to 5 years, adjusted for your home

The National Air Duct Cleaners Association (NADCA) generally suggests having residential duct systems inspected and cleaned every three to five years. The U.S. Environmental Protection Agency takes a more case-by-case view: clean ducts when there's a clear reason, such as visible mold, a pest problem, or enough dust and debris that particles blow out of the supply registers.

Use three to five years as a baseline, then move it sooner if your home has risk factors. In the Pacific Northwest, damp weather is a big one.

Why Northwest homes often need it sooner

Damp air and mold risk

From October through spring, outdoor humidity stays high and homes are closed up. Moisture from cooking, showers and drying laundry has fewer places to go. When damp air meets dusty ductwork, especially ducts running through crawl spaces, it can lead to musty odors and, in the worst cases, mold growth. The EPA recommends keeping indoor humidity below 60%.

Crawl spaces and older ducts

Many homes in the region, including older houses in Tukwila and SeaTac, have ducts running through crawl spaces or unconditioned spaces. Gaps in those ducts can pull in damp, dusty air and even insulation fibers.

Wildfire smoke

Smoke from fires in the Cascades, Oregon and British Columbia has become a regular late-summer event. Fine smoke particles get inside even with windows closed and can settle in the duct system. After a heavy smoke event, change the filter and consider an inspection.

Trees, pollen and moss

Evergreen and alder pollen peak in late winter and spring, and grass pollen follows in early summer. Heavy tree cover also means more organic debris around the home.

Signs it's time to clean your ducts

• A musty or damp smell when the heat comes on
• Dust puffs out of the vents when the system starts
• Furniture gets dusty again soon after cleaning
• Allergy or asthma symptoms that are worse indoors
• Some rooms get weak airflow
• Visible debris, growth or pest droppings at the registers

What you can do between cleanings

• Change the filter every 1 to 3 months, and right after a smoke event.
• Run bathroom and kitchen fans to move moisture out of the house.
• Make sure the dryer vents outdoors and isn't clogged, since a blocked vent pushes moisture into the home.
• Keep the crawl space dry and check that its vapor barrier is in place.

Book a cleaning

Moment Air Duct Cleaning Renton offers air duct cleaning for $199 per HVAC unit with unlimited vents, dryer vent cleaning for $99, and deep duct cleaning for $59 per vent. We serve Renton and communities within about 50 miles. Call (206) 895-6644 or request a free estimate.