What a Furnace Cleaning Actually Involves

Theisen has had “Furnace Cleaning” in its name for a long time. The company was founded in 1947, and its early trucks were lettered “Theisen, Furnace Cleaning.” The shop still has an old wooden service tag that reads “Cleaned By THEISEN Power Vacuum CLEANER.” Under that headline the tag lists three things: Filters, Smoke Pipe, and a phone number ending in 24787. The tools are newer now. The job is still recognizable.

The short version

A furnace cleaning is a hands-on service visit. A technician opens the furnace, looks it over, cleans the parts that collect dirt, and checks that it still runs the way it should. It is not just a filter swap. It is also not the same thing as duct cleaning, though people mix the two up. Think of it the way the old tag did: filters, smoke pipe, and the working parts in between.

What the technician goes through

Every furnace is a little different, and a good tech adjusts to what he finds. In general, a visit covers these areas.

• The filter. A packed filter is the most common problem and the easiest to fix. It makes the blower work harder and the house heat unevenly.
• The blower compartment. Dust builds up around the blower wheel and motor, and a dirty wheel moves less air than a clean one.
• The burners and ignition. On a gas furnace the tech looks at the burners and the ignition. On an oil furnace he looks at the burner and nozzle. Both need to light cleanly and burn steadily.
• The heat exchanger and flue passages. This is where the flame's heat moves into your house air and where exhaust leaves the furnace. A cracked heat exchanger or a blocked passage is a safety problem, so the tech watches for both.
• The smoke pipe and vent. It is the same smoke pipe named on the old tag. It carries exhaust outside, so it has to be intact, connected, and open.
• The electrical side. Loose connections, worn parts, and thermostat wiring all get a look.

Customers have described the same kind of visit for decades. Carrie G. wrote that the only issue with her furnaces was that the air filters had not been changed recently enough. The techs spotted “the air filter issue in about 30 seconds flat,” she said, then still made sure both furnaces were in good working order and passed along some other maintenance tips. Mary M. wrote that Theisen has kept her furnace in good shape for years and “remember the quirks of my unit.” That memory is part of the value of having the same company come back.

Furnace cleaning versus duct cleaning

Furnace cleaning deals with the equipment. Duct cleaning deals with the passages that carry heated and cooled air through the house. Theisen does both. On its own website, the company says clogged ducts can lead to poor air circulation and pose a fire hazard for a home or business in Yakima, Washington. Dust and debris sitting in the ducts is the thing to worry about, along with whatever else has found its way inside over the years.

A few reviewers described the duct side of the work. Samantha Webster had an old furnace replaced and wrote that the crew “cleaned all of the ductwork and now the fan blows stronger and more evenly throughout the house.” Marichele C. said the crew “cleaned the ducts thoroughly and even cleaned the dirt from the window they put the vacuum through.” Kevin Merrill had his ducts cleaned by a Theisen tech named Zack in 2024 and said, “He didn't rush the job and did a real nice job.”

How often should you do it?

Theisen generally suggests routine service every other year. Some customers like it more often. Dave D. wrote, “I'm sure every other year is adequate, but I like how my furnace operates better after they perform the routine maintenance,” and he has the company out at the start of every winter. Your own schedule depends on the furnace's age, whether you have pets, how dusty the house gets, and how faithfully you change the filter. If you are not sure where you stand, ask when you call.

What you can do between visits

• Check the filter every month during heating season. Replace it when it looks gray and packed.
• Keep the area around the furnace clear. Boxes, paint cans, and laundry baskets do not belong against it.
• Make sure supply vents and return grilles are not blocked by furniture or rugs.
• Notice new sounds and new smells, and tell the tech what changed. Small details save diagnosis time.
• If you ever smell gas, leave the house and call your gas company from outside. Do not wait for a cleaning appointment.

One thing Theisen does not do

Theisen does not normally work on gas fireplaces. If your fireplace needs service, you will want a different company for that, and it is worth asking before you book so nobody wastes a trip. Furnaces, heat pumps, air conditioning, ductless systems, and duct cleaning are the work Theisen does day to day.

Book a cleaning in the Yakima Valley

Theisen serves Yakima, Selah, Moxee, Wapato, Naches, Parker, Ahtanum, and West Valley. The office is open Monday through Friday, 8 to 5. Call (509) 452-4787 and say whether you want furnace cleaning, duct cleaning, or both. It is the same four digits that were on the truck door in the 1950s.