Dryer Vent and Air Duct Cleaning for Washington Homes, Ducted or Not

West of the Cascades, east of the Cascades

Washington's climate splits along the mountains. NOAA's state climate summary notes that Pacific moisture brings frequent precipitation west of the Cascades, while temperatures in the central and eastern parts of the state are less moderated by the ocean and swing more widely through the year. Most of the state's precipitation falls in winter.

The federal county climate map reflects that split: King, Pierce, Snohomish, and Clark counties are in a marine zone (IECC 4C), Spokane County is in a cold zone (5B), and a few northeastern counties are colder still (6B).

In broad terms, that means milder winters and cooler summers on the west side, and bigger seasonal swings on the east side. How much a system runs affects how quickly its filter loads up — one more reason EPA recommends cleaning ducts only as needed rather than on a fixed schedule.

Sources: NOAA State Climate Summaries 2022 — Washington; PNNL for U.S. DOE Building America — Guide to Determining Climate Zones by County (IECC 2021 updates); U.S. EPA — Should You Have the Air Ducts in Your Home Cleaned?

Summer wildfire smoke

NOAA's climate summary describes wildfires during the drier summer months as a particular concern for Washington; in 2015, more than 1 million acres burned — more than six times the average.

For homes with central heating and cooling, the Washington State Department of Health recommends a MERV 13 filter or the highest-rated filter your system can handle, choosing the deepest pleat your system can accommodate to avoid straining it. DOH also advises setting the fan to recirculate and to run continuously ("on," not "auto"), making sure the filter fits tightly, and replacing it when dirty. If you're unsure what your system can handle, DOH suggests checking the HVAC manual or asking an HVAC professional.

Sources: NOAA State Climate Summaries 2022 — Washington; Washington State Department of Health — Protect Yourself and Others: Smoke From Fires

Not every Washington home has ducts

Washington homes are heated in many different ways. Some use a furnace or heat pump that moves air through supply and return ducts; others use systems with no ductwork at all, such as electric baseboard or wall heaters and ductless heat pumps. A Building America study by the Washington State University Energy Program, for example, looked at new homes in Tacoma heated entirely with ductless heat pumps, electric baseboard heaters, and fan-assisted wall heaters.

Zonal heating is not rare, either: the same 2016 study reports that Tacoma Public Utilities counted approximately 22,000 zone-heated homes in its service territory. If your home has no ducts, there's nothing to duct-clean — but if you have a clothes dryer, you still have a dryer vent that needs regular attention.

Source: WSU Energy Program for U.S. DOE Building America — Performance and Costs of Ductless Heat Pumps in Marine-Climate High-Performance Homes (2016)